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  Current Issue
 
2024 Vol.44 Issue.10,Published 2024-10-20
Air Pollution Control
Water Pollution Control
Solid Waste
Soil Pollution Control
Environmental Ecology
Carbon Emission Control
Emerging Contaminants and Environmental Toxicology
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2024 Vol. 44 (10): 0-0 [Abstract] ( 82 ) [HTML 1KB] [ PDF 264KB] ( 583 )
Air Pollution Control
5329 Ionic characteristics and sources of atmospheric precipitation and its impacts on environment at typical cities in China
XIAO Qian, HAN Li-hui, QI Chao-nan, TIAN Jian, LAN Tong, WANG Hai-yan, ZHENG Ai-hua, GUO Jing-hua
Based on the observation data from sampling and the data from the Acid Deposition Monitoring Network in East Asia, the chemical composition, acidity and its causes, wet deposition fluxes, and pollution sources of atmospheric precipitation at typical cities in North, Northwest, Southwest, South and East China in 2019 were studied, and the ecological effects of the precipitation on the environment were evaluated. The results showed that the total ion concentrations in the precipitations showed an obvious seasonal variation with the order of dry season > rainy season, and also presented a significant spatial distribution with the order of Beijing (706.87μeq/L) > Xi'an (369.26μeq/L) > Chongqing (265.17μeq/L) > Xiamen (244.54μeq/L) > Zhuhai (134.31μeq/L) > Wuzhishan (81.88μeq/L). NH4+, Ca2+, SO42- and NO3- were the main ions of precipitation in the inland cities, while Cl- and Na+ had a higher fraction in the coastal cities. The precipitation at the city in North China was mainly neutral, with acid rain events only accounting for 2.3% of the annual precipitation. The precipitation at the city in Northwest China was weakly alkaline, without any acid rain events occurring. The acid rain problem at the city in Southwestern China was severe, with acid rain frequencies reaching 30.3% and 80.3% at the urban and suburban stations, respectively, and presenting significant seasonal changes. The precipitation at the urban station in the city of East China was mainly neutral, however the acid rain problem at the station in remote area was extremely severe, with an annual acid rain rate of 99%. The summer precipitation at the city in Southern China was mainly neutral, while the other seasons were all acidic, and acid rain events accounted for 62.2% of the total precipitation events throughout the entire year. The neutralization capacity indicated that the areas with severe acid rain problems were mainly due to insufficient alkaline components in precipitation. Influenced by precipitation, the wet deposition fluxes of nitrogen and sulfur in each city were larger in the rainy season than those in the dry season, and played an important role in promoting the ecological environment in the rainy season. The wet deposition fluxes of nitrogen and sulfur in China showed a spatial distribution pattern decreasing from the east to the west and from the coastal areas to the inland areas. There were significant differences in the sources and contributions of precipitation ions in different cities, especially in cities with severe acid rain problems. The contribution of dust sources mainly composed of Ca2+ and Mg2+ to precipitation was smaller than that of secondary sources mainly composed of SO42- and NO3-.
2024 Vol. 44 (10): 5329-5343 [Abstract] ( 188 ) [HTML 1KB] [ PDF 3073KB] ( 820 )
5344 Chemical composition and sources of fine particles in Beijing around the Winter Olympics
HUANG Zi-ye, HU Wei, JIN Rui, HOU Sheng-jie, LI Ping, BI Kai, HE Chang-hua, WANG Ya-jie, DUAN Pei-min, LIU Di, WU Li-bin, DENG Jun-jun, SUN Ye-le, FU Ping-qing
To quantify the impact of air quality control measures on the chemical composition of PM2.5 in Beijing, simultaneous observations were carried out at an urban site and a montane background site located northwest of the city around the 2022 Winter Olympics. PM2.5 samples were analyzed for water-soluble inorganic ions and carbonaceous components. Results demonstrated a significant difference in carbonaceous contents between the urban and montane sites. At the montane site, the mean mass ratio of organic carbon (OC) to elemental carbon (EC) was 28.99, and the mean proportion of water-soluble OC (WSOC) in OC was 77%, both of which were significantly higher than at the urban site (12.93 and 48%, respectively). During the observation period, the Beijing-Tianjin-Hebei region and the Liaodong Peninsula were the dominant potential source regions of all the chemical components at the urban site, except for Ca2+. Apart from emissions from the Beijing-Tianjin-Hebei region, particles transported from the Hetao Plain also affected the montane site. The proportion of organic matter (OM) in PM2.5 increased from 22.7% to 31.7% at the urban site, and from 27.7% to 34.9% at the montane site, which might indicate that elevated temperatures and solar radiation favored secondary organic aerosol formation, or that emission sources changed during the latter part of the observation period. During the Winter Olympics, the mass concentration and proportion of nitrates in PM2.5 declined, while the proportion of sulfates increased at the urban site, highlighting the effect of traffic control. The equivalence ratio of anions to cations in PM2.5 at the urban site gradually rose from 0.96 to 1.20, exhibiting elevated acidity. This result may be closely linked to the formation of nitric acid, suggesting a fast rebound in NOx emissions after partial lifting of control measures. Throughout the observation period, the contribution of combustion and secondary sources to PM2.5 exceeded 70% at both sites, reflecting the dominant contribution of anthropogenic particles to PM2.5 in Beijing. However, their contribution dropped by 8.7% during the Winter Olympics at the urban site, indicating that the control of anthropogenic emissions was effective. All the major components in urban PM2.5 declined significantly during the Winter Olympics compared to similar periods in past years. The control measures led to the best air quality during the Winter Olympics compared to similar periods in recent years, despite unfavorable meteorological conditions for pollutant dispersion.
2024 Vol. 44 (10): 5344-5356 [Abstract] ( 148 ) [HTML 1KB] [ PDF 2912KB] ( 722 )
5357 Air quality data restoration based on graph regularization multi-view functional matrix completion
GAO Hai-yan, MA Wen-juan
Due to issues such as sensor malfunctions and data transmission, the collected air quality data often encounter challenges of sparsity and incompleteness. In order to effectively repair and reconstruct the missing parts of air quality data, a Graph Regularized Multi-view Functional Matrix Completion method (GRMFMC) is proposed. Firstly, this innovative method introduces a graph regularization approach that thoroughly takes into account the high-order neighborhood relationship within each pollutant’s sample set, reducing information loss. Secondly, it utilizes the Hilbert-Schmidt Independence Criterion (HSIC) to discern complementary information among various pollutants, thereby improving imputation accuracy. Additionally, by integrating the principles of functional data analysis, the GRMFMC technique treats temporal air quality data as continuous functions, capitalizing on their inherent smoothness and correlation for high-precision data interpolation. Simulation imputations and empirical applications on real air quality datasets both demonstrate that the GRMFMC exhibits superior interpolation performance. In simulation imputations, the GRMFMC method reduces the imputation error by 56%~99% in RMSE and 46%~98% in NRMSE; in empirical applications, it reduces the error by 51%~99% in RMSE and 40%~98% in NRMSE. Furthermore, the GRMFMC method shows consistent robustness across different missing rate and pollutant categories, confirming its potential for generalization capability and practical value in professional settings.
2024 Vol. 44 (10): 5357-5370 [Abstract] ( 107 ) [HTML 1KB] [ PDF 4826KB] ( 653 )
5371 Photochemical oxidation of polycyclic aromatic hydrocarbons in PM2.5 emitted from residential combustion sources
ZHANG Bin, LI Dan, SHEN Zhen-xing, XU Hong-mei, HE Kun, SUN Jian
The emissions of fresh and aged parent polycyclic aromatic hydrocarbons (pPAHs) and oxygenated polycyclic aromatic hydrocarbons (oPAHs) from different residential combustion sources were determined using a potential aerosol mass oxidation flow reactor (PAM-OFR). The results showed that the emission factors of pPAHs decreased by 29.5%~82.9% after atmospheric photochemical oxidation, while oPAHs had an increasing trend. The results demonstrated that pPAHs were emitted directly into the atmosphere through residential combustion sources and were regarded as primary organic aerosol (POA), while oPAHs were generated by photochemical oxidation of organic matter in the atmosphere and were regarded as secondary organic aerosol (SOA). During stimulated photochemical aging, the average decrease of emission factor for pPAHs in biomass burning (73.2%) was significantly higher than that from coal combustion (56.2%), representing that pPAHs emitted from biomass burning have a higher photochemical reaction potential to produce more oxidized substances compared to coal. The present study also showed that the stimulated atmospheric photochemical oxidation process led to a significant increase in the oPAHs/pPAHs ratio and demonstrated a secondary reaction mechanism of pPAHs reacting with hydroxyl radical (·OH) to produce oPAHs.
2024 Vol. 44 (10): 5371-5377 [Abstract] ( 130 ) [HTML 1KB] [ PDF 558KB] ( 755 )
5378 Experiment and process simulation for the removal of low concentration vinyl chloride by ionic liquids
XIAN Jing, WANG Shu-ying, MU Ming-li, DAI Cheng-na
The feasibility of deep vinyl chloride removal from tail gas was investigated by proposing the efficient absorption of vinyl chloride using ionic liquids (ILs). The saturation absorption of three types of ILs (i.e., [BMPYR][Tf2N], [BMIM][Tf2N] and [EMIM][Tf2N]) on simulated vinyl chloride gas with a low concentration (5%) was measured using the equal volume saturation method, followed by an absorption experiment in a packed tower with simulated vinyl chloride gas at an extremely low concentration (0.01%). Subsequently, the concept design and process optimization of vinyl chloride absorption by ILs was performed using Aspen Plus process simulation software. The results indicate that the Henry constant of vinyl chloride is significantly lower than that of nitrogen, and the influence of temperature was relatively small. The experimental results of the absorption tower demonstrate that all the three ILs exhibited excellent removal performance (absorption ratio >94%) of vinyl chloride simulation gas with extremely low concentration (0.01%) under conditions of 25℃, atmospheric pressure, and inlet flow rate of 100mL/min. Among them, [BMPYR][Tf2N] exhibited the highest absorption ratio at 97%. Process optimization results for [BMPYR][Tf2N] absorbing vinyl chloride tail gas (1%, inlet flow rate of 100kg/h) reveal that under optimal operating conditions: number of theoretical plates for absorption tower of 6, a relative operating pressure of 0.25MPa, an IL absorption mass flow rate of 2600kg/h, as well as a temperature of 160℃ and a pressure of 0.001bar for the secondary flash tank, the emitted concentration of vinyl chloride can meet the specified standard (0.0015%). The findings demonstrate that the utilization of ILs for efficient removal of vinyl chloride from exhaust gas and their extensive application can significantly contribute to mitigating the pollution caused by toxic and hazardous substances.
2024 Vol. 44 (10): 5378-5387 [Abstract] ( 106 ) [HTML 1KB] [ PDF 1133KB] ( 850 )
5388 Carbon layer modification on the surface of ordered mesoporous silica-based materials and its VOCs adsorption
KE Quan-li, XIONG Ye-dong, LU Mei, WU Tian-hao, HUANG Kang-kang, MIN Jiong, JIN Chuan-min, CUI Guo-kai, ZHAO Bo, LU Han-feng
Carbon-mesoporous molecular sieve composite materials were synthesized by introducing sucrose into the channels of mesoporous molecular sieves (SBA-15 and MCM-41) followed by chemical etching at high temperatures. By optimizing the sucrose concentration, a balance between surface area, carbon content, and toluene adsorption capacity was achieved. TEM-EDS characterization confirmed that the carbon generated through chemical activation was uniformly distributed within the channels of the mesoporous molecular sieves. Additionally, pore size distribution analysis revealed a significant increase in micropore fractions in both mesoporous materials after functionalization, leading to enhanced toluene adsorption capacity. Notably, compared to C@MCM, C@SBA maintained relatively higher toluene adsorption capacity even after five adsorption-desorption cycles, which translates to a better regenerability. Alongside their excellent adsorption performance, the carbon-mesoporous molecular sieve composites also exhibited remarkable moisture resistance, with no significant decrease in performance under increased humidity. Lastly, both composite materials demonstrated good adsorption performance for other oxygen-containing VOC species, although adsorption was more favorable for nonpolar adsorbates, such as toluene.
2024 Vol. 44 (10): 5388-5396 [Abstract] ( 120 ) [HTML 1KB] [ PDF 1554KB] ( 584 )
5397 Study on visible light catalytic denitrification performance of Ag2O/TiO2 catalyst
WANG Shu-qin, DONG Jian-xin, LI Jin-meng
Anatase TiO2 was prepared by hydrothermal method and compounded with Ag2O to construct a catalyst. BET, XRD, XPS and other catalysts were used to characterize and analyze the catalysts, and NO was used as the treatment object to explore the influence of reaction conditions on the denitrification efficiency of the catalysts. The results showed that under visible light, when the NO concentration in the reaction system was 23.6mg/m3 and the molar ratio of ammonia to nitrogen was 1:1, the best denitrification efficiency of Ag2O/TiO2 (10%) was 92.00%. Further exploration found that the denitrification efficiency remained basically unchanged by changing the flue gas humidity in the reaction system. And when CO2, SO2, NO and other gases are present at the same time, the denitrification efficiency can be maintained at 71.43%. The characterization results showed that the specific surface area increased, the band gap width decreased, the PL peak intensity decreased, and the photocurrent density increased after recombination with Ag2O. After the reaction, the catalyst has a nitro asymmetric stretching vibration peak, so it is speculated that during the reaction process, ·O2-,·OH,·O radicals act as an oxidant to oxidize NO to NO2 and then further oxidize to NO3- to achieve NOx removal. When NH3 and NO2 exist at the same time, the incomplete reaction of NO is further reduced to N2, which promotes the conversion of pollutant gases and further improves the denitrification efficiency.
2024 Vol. 44 (10): 5397-5405 [Abstract] ( 102 ) [HTML 1KB] [ PDF 2174KB] ( 598 )
5406 Preparation of biochar from walnut shells and iodine capture
LI Xing-fa, PAN Han-feng, AN Xiao-wei, MA Xu-li, LI Yong-guo
Using agricultural waste to prepare biochar for iodine capture possess the ecological function of treating waste with waste. The biochar prepared from waste walnut shell has rich pore structure and good thermal stability in this study, and the pore size distribution was dominated by micropores, supplemented by mesopores and macropores. Static adsorption experiments showed that the amount of gaseous iodine captured by biochar could reached 2027mg/g. In aqueous solution, iodine capture experiments showed that 0.1g/L biochar could remove more than 97% of iodine from 20mg/L and 100mg/L elemental iodine within 90minutes at pH=5. 0.4g/L biochar could remove more than 99% of iodine from 20mg/L in cyclohexane within 90minutes. The above properties were better than those of commercial nuclear grade activated carbon under the same conditions. The mechanism study showed that the iodine capture by walnut shell biochar was physical adsorption, and the adsorbed iodine formed polyiodide ions through charge transfer. Pore structure was proved to be an important factor for the high iodine capture performance of walnut shell biochar. Micropores played a leading role in iodine capture. Hierarchical pores contributed to the migration and transfer of iodine inside and outside the biochar structure. The calculation results of density functional theory supported the experimental conclusion that iodine molecules are more easily adsorbed in the pore size matching their own kinetic size for monolayer adsorption.
2024 Vol. 44 (10): 5406-5414 [Abstract] ( 149 ) [HTML 1KB] [ PDF 1076KB] ( 767 )
5415 Regulating the morphology of Cu/CeO2 catalysts to enhance their water-resistant for low temperature CO oxidation
XUE Jing, LI Qiao-yan, LI Shu-ning, LIANG Mei-sheng
Herein, tube-, rod- and particle-like Cu/CeO2 catalysts were synthesized and their structure-performance relationship for CO oxidation in moist conditions was explored. The results revealed that the tube-like catalysts (CuCe-NT) exhibited excellent low-temperature activity and superior H2O resistance stability. The characterization results indicated that CuCe-NT catalyst had a lower crystallinity, larger surface area and more structural defects in comparation with rod-like (CuCe-NR) and particle-like (CuCe-NP) samples, which greatly strengthened the interactions between CuOx and CeO2, thus boosting the redox of Ce4+/Ce3+ and Cu2+/Cu+, and the surface enrichment of Ce3+ and Cu+, further facilitating the CO adsorption and oxidation. Moreover, the hollow structure of CuCe-NT catalyst with a large pore size effectively inhibited the associatively adsorption of H2O, suppressing the generation of inert OH groups on oxygen vacancies, and thus maintaining its higher oxidization in the presence of water. In situ-DRIFTS showed that compared to CuCe-NP catalyst, the nanotube structure of CuCe-NT catalyst alleviated the competitive adsorption of H2O with CO, and inhibited the formation of bridged carbonates, thus ensuring the CO oxidation under humid atmosphere. This study revealed the effect of catalyst structure on its resistance of H2O in terms of H2O adsorption type and reaction mechanism, thus providing an ingenious strategy for the design of H2O-resistant CO oxidation catalysts.
2024 Vol. 44 (10): 5415-5425 [Abstract] ( 97 ) [HTML 1KB] [ PDF 2064KB] ( 709 )
Water Pollution Control
5426 Enhance nitrogen and phosphorus removal via endogenous denitrification of aerobic granular sludge by directional regulation of electron acceptor
LI Dong, LI Yu-meng, JIANG Peng-fei, WANG Tian-shuo, ZHANG Jie
In order to strengthen endogenous denitrification and enhance the efficient utilization of limited carbon sources, in this study, one anaerobic/aerobic/anoxic (A/O/A) sequencing batch reactor and three groups of anaerobic/two-stage short-time aerobic/anoxic (A/(O/A)2) sequencing batch reactors with different aerobic time allocations were implemented to assess sludge granularity and the enrichment of denitrifying glycogen accumulating organisms (DGAOs) across directional regulation of electron acceptor. The findings indicated that the aerobic granular sludge in the two-stage short-time aerobic/anoxic reactor exhibited a more compact structure, superior sedimentation performance, increased availability of electron acceptors in both anoxic and aerobic phases. Furthermore, the capability of DGAOs to accumulate endogenous carbon sources was enhanced. The competition between denitrifying polyphosphate accumulating organisms (DPAOs) and DGAOs for carbon sources reached an equilibrium state within the system. Consequently, the system demonstrated heightened endogenous denitrification and nitrogen removal rates, thereby achieving profound nitrogen and phosphorus removal. Notably, among these reactors, R2, featuring a two-stage short aerobic time allocation of 60minutes in the initial segment and 30minutes in the subsequent segment, exhibited optimal denitrification and phosphorus removal efficacy. This reactor displayed the highest content of DGAOs and superior particle settling performance. During the stable operational phase, R2achieved removal rates of 90.52%, 85.71%, and 92.73% for COD, TN, and TP, respectively. Additionally, the endogenous denitrification efficiency reached 58.59%, underscoring its commendable pollutant removal capabilities.
2024 Vol. 44 (10): 5426-5434 [Abstract] ( 118 ) [HTML 1KB] [ PDF 2101KB] ( 637 )
5435 Effects of hydraulic shear force and influent ammonia nitrogen loading rate on the recovery of deteriorated nitrifying granules
ZHAO Wei, FENG Yu, XU Hao-Zhe, ZHANG Xing-Yu, ZHOU Han, ZHANG Liang-wei, JIANG Kuan-sheng, LIU Wen-ru
Three reactors inoculated with deteriorated nitrifying granules were employed to characterize the effects of hydraulic shear force and ammonia nitrogen loading rate on granular recovery. The deterioration of the nitrifying granules was further observed in the control reactor R0 with ammonia nitrogen loading rate of 1.6g/(L·d) and hydraulic shear force of 1.31cm/s. Additionally, the nitrifying granules exhibited over-secretion of extracellular polymeric substance (especially proteins), resulting in a significant biomass loss. However, due to the presence of higher residual ammonia concentrations (>25mg/L), the nitrite accumulation efficiency in the R0was consistently above 85% with the NOB abundance lower than 0.66%. In R2 with ammonia loading rate of 1.6g/(L·d) and hydraulic shear force of 2.62cm/s, the settling properties of the nitrifying granules was improved, although the morphology of the granules resembled bars. Furthermore, the accumulation of nitrite was eliminated due to the enrichment of NOB in R2 (the relative abundance of Nitrobacter was 10.47%). The nitrifying granules underwent successful regranulation in R1 with ammonia loading rate of 0.8g/(L·d) and hydraulic shear force of 1.31cm/s. Consequently, the sludge volume index (SVI5) was reduced from 55.6mL/g to 14.6mL/g, while the average granular size was reduced from 579μm to 294μm. The results of in-situ batch tests demonstrated that AOB and NOB in the nitrifying granules were stratified. In addition, high-throughput sequencing results showed that the differences in hydraulic shear force and ammonia loading rate caused the significant variations in the microbial community structure in each reactor. Therefore, it can be concluded that regulating the microbial growth rate by reducing the ammonia loading rate exerts a more pronounced positive impact on the restoration of nitrifying granules than hydraulic shear force.
2024 Vol. 44 (10): 5435-5444 [Abstract] ( 110 ) [HTML 1KB] [ PDF 1883KB] ( 615 )
5445 Effect of C/N on biogas production and organic and nitrogen removal performance in an EGSB system
ZHOU Xin, ZHAO Rui-qiang, HAN Jing
An expanded granular sludge bed (EGSB) was used to treat high-strength organic wastewater containing both ammonia and nitrate. The effects of carbon to nitrogen ratio (COD/TN) on biogas production and nitrogen and carbon removal were mainly investigated. The 136-day operating results showed that C/N had no significant effect on COD removal, while significantly affected methanogenesis and TN removal efficiency. The time-course water quality determination confirmed nitrite accumulation and the coupling of nitrate partial reduction with anaerobic ammonia oxidation (Anammox). When C/N was 5.71, the coupling effect of Anammox with methanogenesis and nitrate partial reduction was optimal. With the rise of C/N, anammox activity decreased, while activities of methanogenesis and nitrate dissimilation reduction (DNRA) increased. C/N could significantly change the composition, content and organic groups of extracellular polymeric substance in sludge, and then affect the stability of sludge structure and microbial metabolic activity. The relative abundances of Candidatus Kuenenia and Candidatus Brocadia of Anammox bacteria were much higher at low C/N than those at high C/N. At high C/N, a large number of methanogens including Methanothrix, Methanolinea and Methanobacterium were detected, meanwhile, denitrifying and DNRA bacteria were co-existed. Microbial functional gene annotation proved that partial denitrification/DNRA promoted nitrite accumulation and thus Anammox occurrence, as well as methane production via acetic acid pathway. Finally, synchronous carbon and nitrogen removal mechanism was proposed at optimal C/N.
2024 Vol. 44 (10): 5445-5452 [Abstract] ( 111 ) [HTML 1KB] [ PDF 844KB] ( 646 )
5453 The effect of ammonia nitrogen stress on anaerobic digestion treatment of high concentration organic nitrogen wastewater
DANG Peng-ze, TAN Xin-wei, LI Xiang, YUAN Yan, HUANG Yong, LI Peng-fei, FENG Zheng
Using actual membrane wastewater as an example, this study explored the dynamic responses of methanogenesis and microbial communities in high-concentration organic nitrogen wastewater under ammonia stress, clarifying the ammonia inhibition threshold, inhibition form, inhibition mechanisms, and response strategies. The results indicate that the primary form of ammonia inhibition in anaerobic digestion (AD) treatment of high-concentration organic nitrogen wastewater is free ammonia (FA), with an inhibition threshold of (145±10) mg/L and a half-maximal inhibitory concentration of (244±10) mg/L. During AD treatment of high-concentration organic nitrogen wastewater, the key methanogenic microorganisms include Methanosaeta (acetotrophic methanogens), Methanomassiliicoccus and Methanomethylovorans (methylotrophic methanogens). The activities of Methanosaeta and Methanomethylovorans decline at ammonia nitrogen levels above 300mg/L and 900mg/L, respectively. Simultaneously, the functional microbes related to hydrogen and carbon dioxide production are inhibited when FA exceeds 140mg/L. This leads to the accumulation of small organic molecules with more than one carbon atom in the system, ultimately resulting in reduced chemical oxygen demand removal efficiency and incomplete release of ammonia nitrogen under high free ammonia (FA) conditions. After severe ammonia inhibition, recovery of the system can be achieved by adjusting the pH, but not through microbial acclimatization.
2024 Vol. 44 (10): 5453-5460 [Abstract] ( 113 ) [HTML 1KB] [ PDF 1343KB] ( 756 )
5461 Effects and mechanisms of polypropylene nanoplastics on biological denitrification and functional genes
HUANG Jiang, XU Jun-shuai, ZHANG Hua, LUO Tao, HE Chun-hua, LIU Jun, SHUAI Zi-chen
Polypropylene nanoplastics (PP NPs) were selected to research their effects on biological nitrogen removal. The water quality, nitrogen transformation functional gene, and biological activity were detected. The effects and mechanisms of different concentrations of PP NPs (1~100mg/L) on biological denitrification and functional genes were explored by examining the water quality indexes, the abundance of functional genes for nitrogen transformation, and the metabolism content of substances in the process of denitrification in the sludge system in each reactor, and by employing the methods of Pearson's correlation analysis and linear regression modeling analysis. The results showed that the inhibition effect increased with the increase of PP NPs concentration. The effects of low concentration of PP NPs on the nitrogen removal performance were weak, and the effluent COD, effluent ammonia nitrogen, and nitrate nitrogen removal at the aerobic end were reduced to 85%, 91.4%, and 66%, respectively, under the influence of 100mg/L PP NPs. The qPCR showed that the abundance of nitrogen transformation function genes, except nirK and norB genes, decreased gradually with the increase in the concentration of PP NPs, among which 16S rRNA, amoA, nxrA, narG, napA, nirS, nosZ genes showed the highest decreases of 6.82%, 23.78%, 26.25%, 14.56%, respectively. 24.90%,26.37%,21.04%. With the increase in the concentration of PP NPs, the intracellular ROS and LDH contents increased up to 33.36% and 13.55%, respectively, and the sludge cells were in a state of severe oxidative stress, which led to the damage of the cell membrane structure and the decrease of cellular activity. Pearson's correlation showed that there were strong correlations between physicochemical parameters and some functional genes. The negative correlation between nitrate-nitrogen at the aerobic end and functional genes changed to a positive correlation under the stress of 1mg/L PP NPs. Positive correlations of varying degrees were observed between ammonia-nitrogen of effluent and nxrA, nirK and norB genes under the stress of 1~100mg/L PP NPs. Linear regression modeling indicated that the amoA and nxrA were the key driving factors for ammonia oxidation and nitrification, nirS was the key driving factor for nitrite reduction, and nosZ and narG were the key driving factors for denitrification. In this study, the effects and mechanisms of PP NPs on biological nitrogen removal were revealed from the perspective of molecular biology.
2024 Vol. 44 (10): 5461-5471 [Abstract] ( 108 ) [HTML 1KB] [ PDF 1270KB] ( 765 )
5472 Effects of Fe-C co-substrate environment on iron-based denitrification efficiency and microbial community in wastewater
ZHENG Lei, WU Hao-ming, WANG Xue, CHENG Li-rong, TAN Qiu-yang, XING Yu-zi, TIAN Qi, ZHANG Yao-xin
A co-substrate ferrous denitrification system was constructed and the effects and mechanisms of low-concentration organic carbon (0,3,6,9,12mg/L) on iron-based denitrification under different Fe/N (2, 3, 4) conditions were investigated by gradient experiments, providing theoretical reference for improving the efficiency of iron-based denitrification. The results showed that the optimal concentration of organic carbon source was 9mg/L in this experiment. When Fe/N = 3 and 4, the denitrification efficiency increased by 22.7% and 9.1% respectively compared with that without carbon source, and the promotive effect decreased with the increase of carbon source concentration and Fe/N. The addition of organic carbon had little effect on the diversity and evenness of microbial communities. With the increase of concentration, the total node degree of autotrophic bacteria such as Rhodanobacter and mixotrophic bacteria such as Comamonas and Thauera in the ecological network was always higher than that of heterotrophic denitrifying bacteria. When C/Fe = 0.140and 0.187 (i.e., carbon source concentrations of 6mg/L and 9mg/L), the synergistic and symbiotic relationship in the ecological network exceeded 65%, and the carbon source achieved the highest gain effect per unit concentration and the highest denitrification efficiency, respectively. The autotrophic process contributed 39.2% and 56.5%, respectively, to the system denitrification, both of which were dominant. The increase in the abundance of functional genes that dominate NO3-, NO2-, and NO reduction in the system is also an important reason for improving the NO3--N removal efficiency of the iron-based co-substrate denitrification system.
2024 Vol. 44 (10): 5472-5480 [Abstract] ( 123 ) [HTML 1KB] [ PDF 1738KB] ( 513 )
5481 Effects of eggshell microcarriers on the rapid cultivation of nitrifying granular sludge
JIANG Kuan-sheng, TANG Hao-ting, LONG Jing, LI Ming-jun, ZHANG Liang-wei, ZHOU Han, ZHAO Wei, LIU Wen-ru
The influence of adding eggshell microcarriers on the rapid cultivation of nitrifying granular sludge was investigated in a continuous flow gas-lift internal circulation reactor. The results showed that the reactor (R2) with the addition of 0.5g/L eggshell microcarriers (75μm) achieved sludge granulation within one month, which was 1~2weeks earlier compared to the control (R1). Furthermore, the resulting granular sludge in R2 exhibited higher mixed liquor volatile suspended solids (MLVSS) (R1=1.7g/L, R2=2.2g/L), Tightly Bound-EPS (TB-EPS) content (R1=97.65mg/gVSS, R2=136.29mg/gVSS), TB-PN/PS ratio (R1=2.95, R2=4.73), and better settling performance (with respective SVI3and SVI30 values of 41.67, 37.5mL/g for R1, and 30.36, 28.57mL/g for R2). Compared to R1, the granular sludge in R2had higher activity, with specific oxygen uptake rate (SOUR) and specific ammonia oxidation rate (SAOR) values of 754mgO2/(gVSS·h) and 90.74mg/(gVSS·h), respectively. High-throughput sequencing results indicated that the granular sludge supplemented with eggshell microcarriers had a higher abundance of nitrifying bacteria (Nitrosomonas) and EPS-producing bacteria (such as Comamonadaceae__unclassified).
2024 Vol. 44 (10): 5481-5489 [Abstract] ( 109 ) [HTML 1KB] [ PDF 1987KB] ( 503 )
5490 Numerical simulation and nitrogen removal mechanism of a novel airlift dual transverse internal loop reactor
LIU Ye-xing, YU Li-fang, CHEN Qian-yi, DAI Bu-feng, CAO Wan, PENG Dang-cong
A novel airlift dual transverse internal-loop (ADTL) reactor was set up and operated for the treatment of synthetic municipal wastewater, aiming to eliminate internal circulation energy consumption of conventional biological nitrogen removal process. The key structural parameters, such as the ratio of top clearance height to liquid level height (Htc/Hl), bottom clearance height/liquid level height (Hbc/Hl) and A/O, were optimized by Computational Fluid Dynamics (CFD) simulation. Subsequently, an optimized ADTL reactor was long-term operated to investigate nitrogen removal performance, functional bacterial activity, enzymatic activity, and microbial community structure characteristics. The CFD numerical simulation results revealed that when the Htc/Hl、Hbc/Hl and A/O were 0.08,0.08 and 1:1, respectively, the liquid circulation velocity and liquid flow uniformity of the ADTL reactor were better. The long-term operating performance of the reactor demonstrated that, in comparison with the conventional internal circulation mode, the ADTL mode achieved an 11.96% increase in total nitrogen removal efficiency. In addition, the ratio of specific nitrite utilization rate to specific ammonia utilization rate (SNUR/SAUR) decreased from 1.71 to 1.13, while the ratio of specific nitrite reduction rate to specific nitrate reduction rate (NIRR/NARR) increased from 0.39 to 0.66. Corresponding trends were also observed in the enzymatic activity ratios. Additionally, Illumina MiSeq sequencing analysis revealed significant increases in the abundance of nitrite-reducing bacteria such as Levilinea (21.58%), Melioribacter (4.54%), and Burkholderia (1.71%) during the ATDL stage. Conversely, the abundance of nitrate-reducing bacteria like Azospira (0%), Denitratisoma (1.49%), and Dechloromonas (0.84%) was relatively low. These findings suggested that the ADTL reactor effectively repulses the nitrite loop associated with conventional internal circulation mode, leading to reduced aeration energy consumption during nitrification and decreased carbon source requirements during denitrification. Therefore, these results demonstrated the potential of the ADTL reactor to enhance the quality and efficiency of municipal wastewater treatment plants, providing valuable technical support for improving wastewater treatment.
2024 Vol. 44 (10): 5490-5498 [Abstract] ( 106 ) [HTML 1KB] [ PDF 2602KB] ( 676 )
5499 V(Ⅴ) reduction by iron minerals combined with Shewanella oneidensis MR-1 and its mechanism
ZHOU Ya-qi, CHEN Qian-yan-yü, ZHANG Jie, SI You-bin
Minerals in collaboration with microorganisms can reduce highly toxic V(V) to less toxic and less mobile V(IV), thereby achieving the purpose of vanadium pollution control. Using Shewanella oneidensis MR-1 as the test strain and pyrite, siderite, and mackinawite as the test iron minerals, this research investigated the characteristics of V(V) reduction by iron minerals combined with microorganisms. Meanwhile, the factors affecting V(V) reduction were examined, and the impact of mackinawite combined with S. oneidensis MR-1on the reduction of V(V) regarding intracellular enzyme activity, extracellular polymeric substances (EPS), and electron transfer were determined. The results showed that all three iron minerals promoted the reduction of V(V) by S. oneidensis MR-1, with mackinawite being the most effective, increasing the reduction rate of V(V) from 80.84% in the control group to 95.54%. The reduction rate of V(V) by mackinawite in conjunction with S. oneidensis MR-1 was inversely proportional to the initial V(V) concentration and pH value, and directly proportional to the amount of added mineral and inoculated bacteria. The addition of mackinawite enhanced the contents of intracellular nitrate reductase (NAR), nitrite reductase (NIR), reduced nicotinamide adenine dinucleotide (NADH) and ATP, increased the contents of proteins, polysaccharides and nucleic acids in EPS, and enhanced electron transfer capability, thereby promoting the bioreduction of V(V). Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) showed that mackinawite promoted the reduction of V(V) to insoluble V(IV) by S. oneidensis MR-1, forming precipitates that accumulated around the bacterial cells.
2024 Vol. 44 (10): 5499-5512 [Abstract] ( 101 ) [HTML 1KB] [ PDF 2714KB] ( 748 )
5513 Degradation of levofloxacin by electro-Fenton with CNT supported nano-iron cathode
FENG Fan, GUO Bo, CAO Qun, JIN Shi-yi, WANG Rui-lin, CHEN Cai-yu
Carbon nanotubes (CNT) were modified using concentrated sulfuric acid, and the modified CNTs (MCNT) were employed as the support for iron (MCNT-Fe) to construct a heterogeneous electro-Fenton system with the cathode of MCNT-Fe for the removal of levofloxacin (LFV). Characterization results of the cathode material by SEM, XPS, XRD, and FTIR revealed that the loaded iron existed in the form of nano-Fe2O3 with the majority of particles (>80%) being smaller than 8nm, while various oxygen-containing functional groups were found on the surface of MCNT. Analysis of the cyclic voltammetry curves (CV) and impedance spectra (EIS) of the cathode materials indicated that the MCNT-Fe cathode exhibited greater oxygen reduction activity and stronger electron transfer capability than CNT and MCNT. Consequently, the electro-Fenton with the MCNT-Fe cathode demonstrated higher LFV removal efficiency. Under optimized conditions, the LFV removal efficiency could reach 92.7%~95.7% in range of pH 3~9 after 240min reaction. The Singlet oxygen (1O2) was identified as the primary reactive oxygen species (contributing to 64.6%). Furthermore, the MCNT-Fe cathode exhibited stable performance during multiple cycles with LFV removal rate of 89.3% after six cycles. The expanded pH range, stable cathode performance, and excellent LFV removal performance make the electro-Fenton method with MCNT-Fe cathode highly suitable for practical application. The proposed mechanism for the formation of 1O2 provides theoretical support for its application.
2024 Vol. 44 (10): 5513-5521 [Abstract] ( 116 ) [HTML 1KB] [ PDF 1853KB] ( 854 )
5522 Kinetic and mechanistic effects of NO2- on the degradation of 4-chloro-3,5-dimethylphenol in water by ferrate
LU Ying, YAO Bin-bin, YANG Pei-zeng, JI Yue-fei, CHEN Jing, LU Jun-he
We investigated the impact of NO2- on degradation efficiency, products, and toxicity of 4-chloro-3,5-dimethylphenol (PCMX) during ferrate (Fe(VI)) oxidation. Results demonstrated that Fe(VI) effectively degraded PCMX in water within the pH range of 7~9, achieving a 100% removal in 5minutes with a [Fe(VI)]:[PCMX] ratio of 10:1. The presence of 0.1~10mg/L humic acid (HA) significantly enhanced PCMX degradation. The addition of NO2- inhibited the reaction, and resulted in the formation of various nitrated byproducts. Quenching experiments indicated that high-valent iron species play a key role in this process. Toxicity assessment suggested that these nitrated byproducts and coupling products exhibited prolonged persistence and biotoxicity. For example, OP-6 and OP-7 have half-lives exceeding 180 days, bioaccumulation factors greater than 5000, and chronic toxicity values less than 1mg/L, which may pose certain environmental risks.
2024 Vol. 44 (10): 5522-5529 [Abstract] ( 147 ) [HTML 1KB] [ PDF 894KB] ( 624 )
5530 Electrochemical advanced oxidative degradation of amino tri (methylene phosphonic acid)
SU Shuang-you, ZHANG Yu-ling, HU Li-li, JIN Wen-zhang, WANG Shu-qin
The degradation efficiency of the electrochemical advanced oxidation process on ATMP was explored using a plate and frame electrochemical advanced oxidation device to investigate the effects of key parameters such as solution flow rate, temperature, pH, current density, and Na2SO4 concentration value; The degradation mechanism of ATMP was explored using electron paramagnetic resonance testing, free radical quenching experiments, and ATMP degradation kinetics. The results showed that when the solution flow rate was 450mL/min, temperature was 30℃, pH was 9, current density was 300A/m2, and concentration of electrolyte Na2SO4 was 0.1mol/L, the degradation rate of ATMP was the highest, reaching 99.7% within 80minutes, the Electrochemical Advanced Oxidation Process (EAOPs) was found to effectively degrade ATMP; In operating conditions, it was observed that changes in current density, solution flow rate, and temperature could affect the ATMP degradation rate, however, a change in temperature required high energy consumption, while the solution flow rate had little impact on the degradation rate, only a change in current density offered the advantage of low energy consumption and a significant impact on the ATMP degradation rate, therefore, this system was deemed suitable for using current density as the core control parameter of the reaction; The •OH (hydroxyl radical) and SO4-• (sulfate radical) generated by the EAOPs system used in this study are both involved in the degradation of ATMP, with reaction rate constants of k•OH,ATMP=(7.50 ±0.05)×108L/(mol·s) and kSO4-•,ATMP=(5.63 ±1.20)×107L/(mol·s), respectively, the •OH (hydroxyl radical) was found to play a major role in the degradation of ATMP.
2024 Vol. 44 (10): 5530-5538 [Abstract] ( 94 ) [HTML 1KB] [ PDF 1077KB] ( 782 )
5539 Role of surface secondary mineral on tylosin degradation mediated by the pyrite oxidation process
SHU Xiao-hua, QIN Zi-qi, NIE Chang-da, ZHOU Jin-wen, ZHANG Teng-fei, ZHANG Qian
This study investigated the photodegradation performance and mechanisms of pyrite, with varying degrees of oxidation, on the macrolide antibiotic tylosin (TYL), which is extensively used in animal husbandry. The results indicated that oxidized pyrite significantly enhanced its photocatalytic degradation efficiency towards TYL. The surface roughness of the oxidized pyrite samples increased, leading to a larger specific surface area and a greater number of active sites for surface reactions, which improved the adsorption capacity for TYL. Moreover, the surface electron transfer process of oxidized pyrite was significantly enhanced, which accelerated the production rate of hydroxyl radicals (·OH) and improved the photodegradation efficiency of TYL. Additionally, the interaction between pyrite (FeS2) and the newly formed Fe2O3 on the surface created a heterojunction that effectively inhibited the recombination of photogenerated electrons and holes within the material, thereby augmenting the photodegradation performance.
2024 Vol. 44 (10): 5539-5546 [Abstract] ( 108 ) [HTML 1KB] [ PDF 1469KB] ( 627 )
5547 Significantly enhanced degradation of organic dyes by Cu(II) activated peracetic acid with hydroxylamine
OU Jie-li, LIU Yi-qing, TANG Yu-qi, FU Yong-sheng
The degradation of methylene blue (MB) was enhanced by using hydroxylamine hydrochloride (HA) to activate peracetic acid (PAA) in the presence of Cu(II). The effects of initial solution pH, reactant dosages, common anions and natural organic matter in the water environment on the MB removal efficiency in the HA/Cu(II)/PAA system were investigated. The activation mechanism of PAA in the HA/Cu(II)/PAA system was explored by identifying the main active species in the system. In the experiments, 400 μmol/L HA was added into 200μmol/L Cu(II) and PAA system under pH 7.0. The results showed that the MB removal rate was increased from 14.7% to 74.1%, and the degradation rate increased from 0.0047 to 0.2271min-1 after 30 minutes of reaction. The introduction of HA promoted the conversion of Cu(II) to Cu(I), which facilitated the catalytic decomposition of PAA, leading to the generation of more reactive species in the system. Based on the results of radical quenching experiments, hydroxyl radicals (HO•) were found to dominate the oxidative degradation of MB. The degradation of MB was significantly affected by the solution pH. The neutral and slightly alkaline conditions were more favorable for the degradation of MB in the HA/Cu(II)/PAA system. The coexistence of Cl- and HCO3- inhibited the degradation of MB, while the natural organic matters had a certain promoting effect on the degradation of MB.
2024 Vol. 44 (10): 5547-5555 [Abstract] ( 109 ) [HTML 1KB] [ PDF 1161KB] ( 682 )
5556 Urea-modified Bi2MoO6 friction-catalyzed oxidative degradation of rhodamine B
XING Yu-lu, XUE Yi-ran, CHEN Ning, SHI Huan-xin, XU Hao, GAO Bo, ZHANG Liu-ke, MA Bing-rui, ZHAO Bao-xiu, LI Jin-cheng
Urea modified Bi2MoO6 (Urea-Bi2MoO6) catalyst was prepared by a hydrothermal method, and its microstructure was characterized by SEM, XRD, XPS, BET, etc. The crystallinity of Bi2MoO6 modified by urea was improved, and it exhibited excellent frictional catalytic performance. Under the conditions of a rotational speed of 700r/min, RhB initial concentration of 5mg/L, catalyst dosage of 1g/L, and 35mm PTFE magnetic particles, the degradation of RhB reached 99.02% after 300min. The friction catalyzed oxidation degradation of RhB by Urea-Bi2MoO6 followed first-order reaction kinetics equation After 5cycles of Urea-Bi2MoO6 friction catalysis, RhB degradation remained above 91.6%. EPR confirmed that h+,•O2-, and • OH radicals were generated during the friction catalytic process of Urea Bi2MoO6. And scavenger test for radicals confirmed that h+ was the main substance causing RhB to be degraded. Urea-Bi2MoO6 is stimulated by friction, producing electron (e-)-hole (h+) pairs. H+reacts with OH-to generate •OH, and e- reacts with O2 in water to generate •O2-, then RhB is degraded by them.
2024 Vol. 44 (10): 5556-5565 [Abstract] ( 108 ) [HTML 1KB] [ PDF 2246KB] ( 677 )
5566 Photocatalytic degradation of imidacloprid in water by Ag/AgCl/ZnO/ATP
WANG Yang-yang, YANG Jia-wei, SUN Lei, WANG Jia-ning, YE Jing-yi, BAO Jia-hua, YANG Liu
Ag/AgCl/ZnO/ATP heterojunction composite photocatalysts were successfully prepared by hydrothermal and precipitation-photoreduction methods. Due to its high efficient photocatalytic activity, the Ag/AgCl/ZnO/ATP was investigated the photodegradation performance and mechanism of imidacloprid (IMI) in water. And it exhibited excellent photocatalytic performance under visible light irradiation, and the removal ability for IMI within 30min. The degradation process conformed to the quasi-primary kinetic model, and its reaction rate constant was 7.2 times higher than that of AgCl. The photodegradation of the IMI well executed within the pH range of 5~11. Both SO42- and NO3- have a certain promotion effect on the degradation of IMI in the water, and the efficient photocatalytic performance and stability can still be maintained after 5 cycles of reuse. Combined with the characterization and experimental validation, it can be seen that the composition of the AgCl/ZnO heterojunction effectively inhibits the complexation of electron-hole pairs. Which allows IMI to undergo nitroxide removal, dechlorination, and ring-opening of pyridine and imidazole under the action of the active substances (h+, ·O2-, and ·OH), and ultimately realizes the efficient degradation of IMI.
2024 Vol. 44 (10): 5566-5575 [Abstract] ( 91 ) [HTML 1KB] [ PDF 1546KB] ( 612 )
5576 Catalytic degradation of perfluorohexanesulfonate by transition-metal coenzymes: Optimization of the biomimetic systems
ZENG Yu-yuan, CHEN Ling-xin, YANG Zhi-min, LIU Shu-po, ZHOU Zhen-ming, ZOU Jing, LI Fei
Biomimetic systems containing transition-metal coenzymes as catalyst have been optimized for simultaneous degradation and defluorination of both linear- (L-PFHxS) and branched-perfluorohexanesulfonate (Br-PFHxS). Vitamin B12 (VB12) catalyzed the reductive degradation and defluorination of both L-PFHxS and Br-PFHxS, whereas hematin did not. For cofactor 430 (F430), biomimetic degradation and defluorination was only found for Br-PFOS but not for L-PFHxS. However, the removal rate and defluorination rate of technical PFHxS catalyzed by VB12 were both much higher than that catalyzed by F430. Biomimetic degradation of technical PFHxS catalyzed by VB12as well as F430 could well be described by a first-order exponential decay model, indicating that the spiked PFHxS could initially distribute between two completely separate pools with independent degradability, i.e. non-degradable and degradable fractions. The axial ligands of VB12 could impact their catalytic defluorination of PFHxS, and the highest defluorination rate was achieved by adenosylcobalamin. Nanoscale zero-valent zinc (nZn0) is the best electron-donor for the biomimetic system under the experimental conditions. At 60℃ and pH = 9.0, the removal rate and defluorination rate of technical PFHxS were as high as 57.1%±2.9% and 8.19%±0.65%, respectively, with cyanocobalamin as biomimetic catalyst and nZn0as electron-donor, and then the degradable fraction accounted for about 54.6% and its depletion rate was 1.01d-1.
2024 Vol. 44 (10): 5576-5583 [Abstract] ( 84 ) [HTML 1KB] [ PDF 734KB] ( 610 )
5584 Mechanism of highly selective adsorption of phosphate in water by biochar/Ca/La-LDH
GAO Jing-yi, CUI Jia-li, YANG Dong
A novel composite adsorbent (CLYK) of coconut shell biochar/Ca/La layered double hydroxide (Ca/La-LDH) was synthesized via a simple co-precipitation method. The materials were characterized by SEM-EDS, BET, XRD, FTIR and XPS, and the effects of metal loading, adsorbent dosage, initial pH value, co-existing ions and organic matter on phosphate adsorption, as well as the characteristics of adsorption kinetics, isotherms, thermodynamics and site energy distribution were investigated. The results showed that CLYK had good adsorption performance for phosphate, with a maximum adsorption capacity of 214.742mg/g at metal loading of 70%, dosage of 1g/L and pH value of 5. Moreover, CLYK displayed a wide range of pH adaptability with significant adsorption capacity observed between pH 3~10. It also demonstrated high selectivity for phosphate in the presence of coexisting ions and organic matter, and the adsorption-desorption cycle test proved that CLYK has a good reusability. The adsorption process of phosphate by CLYK conformed to the Freundlich and quasi-second-order kinetic model, which was multilayer chemisorption, The thermodynamic analysis indicated that the adsorption was a spontaneous endothermic reaction. Chemical precipitation, formation of inner-sphere complexes via ligand exchange, and electrostatic attraction were mechanisms of phosphorus adsorption.
2024 Vol. 44 (10): 5584-5595 [Abstract] ( 111 ) [HTML 1KB] [ PDF 1991KB] ( 921 )
5596 Arsenic adsorption performance and mechanism using the iron-carbon fiber and nano cerium dioxide incorporated composite adsorbent
ZHUANG Yan, HUANG Jiu, ZHU Xiao-fang, LI Peng
Cerium dioxide nanoparticle was incorporated on the surface of the iron-doped carbon fiber surface for the fabrication of the iron-carbon fiber@CeO2 composite adsorbent. The microstructure and phase composition of the as prepared iron-carbon fiber@CeO2 composite were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) which was conducted to evaluate the wastewater rsenic (As) adsorption performance and affinite mechanisms using this adsorbent. The introduction of iron significantly enhanced the mechanical strength of the micro/nano fibers and promoted the uniform dispersion of cerium dioxide on the carbon fiber surface. Notably, the nano-sized CeO2 was effectively anchored onto the surface of the micro-sized iron-carbon fibers, resulting in a highy exposed and continuous nano cerium dioxide interface. The particle sizes of CeO2 was appropriately 6 to 9 nm. Adsorption experiments conducted under various pH conditions (3to 10) revealed the As ions containing wastewater with a intial concentration of 2mg/L was decreased to below 50μg/L within 2-hour adsorption under wide solution pH. The coexistence of phosphate ions would affect the adsorption of As in composite materials. Furthermore, the iron-carbon micro/nano fiber@CeO2 composite dispalyed outstanding selective affinity for arsenic ions. The adsorption kinetics conformed to the pseudo-second-order model, and the adsorption isotherm data well matched with the Langmuir isotherm, indicating the adsorption behivior is primarily governed by monolayer chemical interactions, with a maximum adsorption capacity of 49.02mg/g. Additionally, the desorption experiments showed that when using the 0.1mol/L NaOH as desorption solution, the arsenic removal efficiency remained above 95% after five cycles of adsorption-desorption repetition, which highlighting the remarkable cyclic stability of the iron-carbon fiber@CeO2 composite adsorbent. The mechnisum study indicated that the adsorption pathway involves ligand exchange between hydroxyl groups and arsenate ions.
2024 Vol. 44 (10): 5596-5606 [Abstract] ( 105 ) [HTML 1KB] [ PDF 3505KB] ( 717 )
5607 The experimental study of cadmium contaminated groundwater remediation by permeable reactive barrier with bamboo charcoal-zeolite mixture
LI Zi-bang, ZHANG Liang, LIU Hao, GONG Xing
This paper analyzes the adsorption mechanism of the Permeable Reactive Barrier (PRB) with bamboo charcoal-zeolite mixture to cadmium, as well as its timeliness combining physico-mechanical tests, static batch tests, dynamic column experiments, microscopic characterization analysis, and groundwater flowing numerical simulation. When bamboo charcoals (particle size greater than 0.18mm) and zeolites (particle size greater than 0.5mm) were mixed in a mass fraction of 1:10 to 3:10, the bamboo charcoal-zeolite mixtures could not only remove cadmium from groundwater effectively, but also had good permeability and shear strength. The adsorption capacity of the bamboo charcoal-zeolite mixtures for cadmium increased with the growing bamboo charcoal ratio and decreasing particle size. The penetration and depletion time of the PRB column decreased with increasing groundwater flowing rate and column concentration. The removal reactions of cadmium by bamboo charcoal-zeolite mixtures mainly included complexation, chelation, and ion-exchange. At a groundwater cadmium contaminated site with a thicker PRB and slower groundwater flowing rate, the effective operation time of the PRB was longer.
2024 Vol. 44 (10): 5607-5619 [Abstract] ( 102 ) [HTML 1KB] [ PDF 4258KB] ( 650 )
5620 A feasibility study on the remediation of complex contaminated groundwater in landfill sites using advanced oxidation-permeable reactive barrier (PRB) approach
YOU Yu-qing, HAO Na, ZHAN Liang-tong, SONG Xue
The complex contamination of COD, NH4+, and Mn2+ in the groundwater of a landfill site in Hangzhou was investigated in this study. A combination of heterogeneous Fenton oxidation and a permeable reactive barrier (PRB) was applied. Three different catalytic oxidation catalyst combinations—activated carbon (AC), biochar (BC), and BC+Fe3O4—were designed and used as active filling materials in the oxidation layer of the PRB, followed by a downstream zeolite adsorption layer. Results from batch and column tests showed that 47% of COD was directly pre-oxidized by H2O2. COD in the oxidation layer was reduced through the combined effects of catalytic oxidation and adsorption. The transport of Mn2+ was influenced by the ash content released from porous carbon materials, resulting in initial precipitation followed by dissolution and subsequent adsorption. Functional groups on the surfaces of AC and BC, such as -OH and -COOH, were involved in the reaction. In the adsorption layer, NH4+ and Mn2+ were exchanged with zeolite ions, leading to changes in the zeolite framework structure. The functional groups -NH and -OH on the zeolite surface were also involved in thorough adsorption. The series combination of the BC+Fe3O4 oxidation layer and the zeolite adsorption layer, with a length ratio of 1:3, was found to exhibit higher removal rates for all three contaminants, the latest PRB breakthrough time (i.e., when the effluent concentration was reduced to 10% of the influent concentration and exceeded the limit), and the highest utilization efficiency at breakthrough, making it the optimal process.
2024 Vol. 44 (10): 5620-5629 [Abstract] ( 125 ) [HTML 1KB] [ PDF 3047KB] ( 758 )
5630 Effect and mechanism of Fe2+-activated molecular oxygen advanced oxidation of p-nitrophenol enhanced by aminocarboxylic acid chelating agents
XIN Si-yi, ZHANG Cheng-wu, WANG Ying-qi, WANG De-yu, ZHAO Wei, QIN Chuan-yu, REN Li-ming
Three advanced oxidation systems, including Fe2+/O2/disodium ethylenediamine tetraacetate (EDTA), Fe2+/O2/trisodium nitrilotriacetate (NTA) and Fe2+/O2/N, N'-Ethylenediamine disuccinic acid (EDDS) systems, were constructed to investigate the effectiveness of the 3systems focr removing target contaminant p-nitrophenol (PNP). The generation process of reactive free radicals, and their contribution of pollutants degradation as well as the enhancement of aminocarboxylate ligands and its underlying mechanisms were also studied and clarified in the system of Fe2+/O2/EDTA and Fe2+/O2/NTA. The highest PNP degradation efficiency of 50.8% and 81.2% were achieved in the system of Fe2+/O2/EDTA and Fe2+/O2/NTA, respectively, under pH=3 and the molar ratio of Fe2+ to ligand of 1:1. The reactive free radicals generated by Fe2+/O2/EDTA system were HO• and O2•-, with two generation pathway (one-electron transfer mechanism: O2→O2•-→H2O2→HO•; two-electron transfer mechanism: O2→H2O2→HO•). initial PNP was reduced to p-aminophenol by O2•-; PNP and its reduction products were oxidized by HO• to hydroquinone and p-benzoquinone, followed with the ring structure breakage. HO• was the major reactive free radicals generated by Fe2+/O2/NTA system by two-electron transfer mechanism. PNP was directly oxidized by HO• to hydroquinone and p-benzoquinone, followed with the ring structure breakage. The mechanisms of the difference in the activation capacity of the two ligands were studied.
2024 Vol. 44 (10): 5630-5638 [Abstract] ( 95 ) [HTML 1KB] [ PDF 1649KB] ( 643 )
5639 Levels and occurrence of legacy and emerging poly- and perfluoroalkyl substances in ship sewage and ballast water
WANG Yu-meng, CHEN Hong, HONG Wan-ting, XU Xue-mei
In order to study the effects of Per- and polyfluoroalkyl substances (PFASs) and their emerging alternatives in ballast water and domestic wastewater of ships on the pollution of PFASs in the marine environment, systematically collected 56samples of black water, grey water, black and grey mixed water, and ballast water from 46ships in 16 ports and analyzed 17 traditional PFASs and 2 novel alternatives in these samples. The concentration of ΣPFASs in the ballast water of the ships ranged from 45.6~97.4ng/L; the concentration of ΣPFASs in the domestic sewage of ships ranged from 24~14681ng/L, and the highest concentration of ΣPFASs appeared in grey water samples. There was no significant difference in the content and assignment of PFASs between different types of ships. Among the traditional PFASs, perfluorooctanoic acid (PFOA) and perfluorobutane sulfonic acid (PFBS) were the compounds with higher percentages in most of the samples; and among the newer alternatives, the concentration of sodium perfluorononenoyloxy benzene sulfonate (OBS) was relatively high, the frequency of 6:2 chlorinated polyfluorinated ether sulfonate (6:2Cl-PFESA) was less frequently detected. The higher concentration of ΣPFASs in the treated marine sewage than in the untreated was attributed to the conversion of precursors to PFASs in the treatment process of sewage of ships.
2024 Vol. 44 (10): 5639-5648 [Abstract] ( 112 ) [HTML 1KB] [ PDF 2039KB] ( 749 )
5649 Efficiency of sulfide control using synergistic calcium peroxide and ferrous ion in sewer pipelines
ZHANG Zhi-qiang, LIU Yu-xin, SUN Yi-fan, ZHAO Lei, REN Xiao-wei, YANG Jing, SONG Shan-shan, REN Ya-ting, LU Jin-suo
This paper proposes a CaO2/Fe2+ collaborative control method for addressing the corrosion and odor issues in sewer systems. The effect of different dosing methods on the kinetics and mechanism of sulfide oxidation was analyzed, followed by the analysis on the effect of the pH level, temperature, inorganic irons and other factors on the oxidative removal efficiency of sulfide. The results showed that the synergistic oxidation of CaO2/Fe2+ for sulfides removal agrees with the pseudo-first-order reaction kinetics with the main active specie of oxidized sulfides of HO·. A molar ratio of CaO2 and Fe2+ of 4:1 corresponds to the optimal the oxidation rate of sulfides. The oxidation rate of sulfide was negatively correlated with correlated with temperature. No significant effect was found for common anions and ammonium ions on oxidation rate. When the ratio of dosage to sewage (W/V) is 0.30%, the recovery period of 50% sulfide generation rate is 8.34 days, which indicates that the synergistic dosing of CaO2/Fe2+ can effectively control the formation of sulfide.
2024 Vol. 44 (10): 5649-5657 [Abstract] ( 117 ) [HTML 1KB] [ PDF 3050KB] ( 688 )
Solid Waste
5658 The impact of enzyme enhancement on municipal sludge biological drying system
LI Zhi-jian, LI Ning, CHEN Lei, ZHU Bing
The effects of enzyme intensification were explored by adding composite enzymes (protease and amylase) to the municipal sludge bio drying system. The addition of these enzymes was found to increase the content of humus precursors and quinone functional groups, enhance the system's electron transfer ability, and promote the efficient degradation of protein and total sugar in the reactor. The rate of reaching high temperature in the bio drying system was increased by 3.75times, with the maximum temperature rising from 59.2℃ to 72.8℃, and the duration of high temperature (>50℃) increasing by 5.56times. Microbial analysis results indicated that the addition of enzymes led to an increase in the abundance of aerobic thermophilic microorganisms such as Firmicutes (Geobacillus, Ureibacillus, Bacillus), Caldibacillus (Thermobacillus). The addition of complex enzymes also enhanced the abundance of Gram-positive bacteria in the biological drying system at high temperatures, strengthened the ATP-binding cassette transporter pathway, accelerated the membrane transport process of small molecular organic matter (amino acids, peptides, carbohydrates, etc.), and improved the supply of microbial metabolizable substances, thereby providing a more sufficient substrate guarantee for the improvement of microbial efficiency in the municipal sludge biological drying system.
2024 Vol. 44 (10): 5658-5669 [Abstract] ( 104 ) [HTML 1KB] [ PDF 3183KB] ( 722 )
5670 Study on carbon oxidation process of coal gangue driven by heat and soil properties of its products
HU Han, ZHANG Qing, XIE Er-man, ZHANG Xin-guang, SONG Hao-ran, TIAN Sen-lin, HU Xue-wei
This study focused on the carbon-based minerals contained within coal gangue and subjected them to low-temperature thermal oxidation to investigate the effects of temperature and time on the conversion efficiency of these minerals and to understand the process by which the carbon-based components in coal gangue were converted into humus. After undergoing 1-3 hours of oxidation at medium and low temperatures (150~180℃), the dissolved organic carbon content of the coal gangue thermal oxidation products increased by more than 20times, from 8.76mg/L to 176.72mg/L. The proportion of organic carbon also increased fivefold, from 1.2% to over 6%, and the level of organic matter nutrients became comparable to that of grade 1soil as classified in soil survey nutrient categories. The enhancement in organic carbon content was attributed to the thermal oxidation process, which transformed the C-C and C=C bonds of the carbon-based minerals into C=O bonds, resulting in the formation of carboxyl and hydroxyl groups, as well as other functional groups. The carbon-based minerals underwent oxygen hydrolysis, leading to their transformation into humic substances such as fulvic acid. The increase in fulvic acid content was shown to effectively improve the moisture retention and aggregation performance of the coal gangue weathering products, enabling the products' water retention to exceed the standard for sandy soil and significantly boosting the biomass of winter pasture by 70%.
2024 Vol. 44 (10): 5670-5677 [Abstract] ( 109 ) [HTML 1KB] [ PDF 2246KB] ( 595 )
5678 Effect of de-alkalized red mud on the distribution of catalytic pyrolysis products from food waste
LIU Liang, ZENG Hong-liang, QING Meng-xia, HE Zi-hang, WU Jia-jun, KANG Xiang-jing, XIANG Jun, LIU Yi-fan
In this paper, the effects of de-alkalized red mud on the distribution of food waste pyrolysis products at different pyrolysis temperatures were investigated using a fixed bed reactor, Gas Chromatography-Mass Spectrometry (GC-MS), Fluorescence Spectrophotometry (UV-F), and In-Situ Infrared (In-situ DRIFTS). The results showed that under the same pyrolysis temperature, the formation of pyrolysis gas was inhibited and the production of pyrolysis oil was promoted, with the highest yield of 39.46% at 450℃, by de-alkalized red mud. The pyrolysis oil was mainly dominated by fatty acids, N compounds, and esters. Not only was the decomposition of triglycerides promoted to produce long-chain carboxylic acids but also the cleavage of proteins was promoted to produce aromatic proteins by de-alkalized red mud, which led to the increase of acid content and deepening of the degree of aromatization in the pyrolysis oil. Meanwhile, the significant growth of carboxylic acid functional groups and C≡N absorption peaks in pyrolysis coke further confirmed that the de-alkalized red mud could promote the production of acids and N compounds in pyrolysis oil.
2024 Vol. 44 (10): 5678-5686 [Abstract] ( 130 ) [HTML 1KB] [ PDF 1435KB] ( 787 )
5687 Solid waste disposal, risk and management —Effect of microplastics on methane production from organic components of municipal solid waste (MSW)
NI Ren-jie, HONG Wen-qing, ZHENG Zi-hao, SUN An-yi, SONG Li-yan
The effects of microplastic exposure levels of different chemical components (polyethylene and polypropylene) and concentrations (20, 40, 80/g polyethylene) on the methane (CH4) production through organic fractions of solid waste decomposition were investigated in batch series of simulated bioreactors. Results show that microplastic exposure significantly (P<0.01) affected the total organic carbon content in the degradation process, which varied from -18.03% to 22.65%; microplastics exposure significantly (P<0.01) promoted the accumulation of acetic acid in the hydrolysis and acidification stage of the degradation process, with an average increase of 19.09%; microplastic exposure significantly (P<0.01) inhibited the production and accumulation of CH4, and the cumulative yield decreased by 21.38% to 46.56%; the exposure of different chemical components of microplastics significantly (P<0.01) affected the CH4 production, and the concentration of polyethylene microplastics had no significant effect on the CH4 production.
2024 Vol. 44 (10): 5687-5695 [Abstract] ( 124 ) [HTML 1KB] [ PDF 845KB] ( 574 )
5696 Impact of manufacture method on the hydraulic performance of polymer-enhanced calcium bentonites
LIU Jun-yi, TONG Shan, LI Yu-chao, LI Jing-jing, DONG Hao-ran
Sodium polyacrylate amended Ca-bentonites (PAAS-CaBs) were prepared by dry mixing, wet mixing, wet kneading and in-situ polymerization. The hydraulic properties of polymer enhanced bentonites under acidic mine drainage solution (AMD) were investigated by swell index and modified fluid loss tests. When tested with AMD, values of swell index, fluid loss and hydraulic conductivity of PAAS-CaBs prepared by dry-mixing, wet-mixing and wet-kneading increased by factors of 1.1~4, 2.7~5.3, and 1.4~2.4, respectively, whereas that of PAAS-CaBs prepared by in-situ polymerization increased by a factor of 4 and decreased by 30% and 97%, comparing to the unamended CaBs. In general, the hydraulic properties of polymer enhanced bentonites under AMD solution deteriorate in the following order: in-situ polymerization > wet-kneading > wet-mixing > dry-mixing. The dry-mixing method is recommended for scenarios with mild contamination and limited budget, whereas the in-situ polymerization method is recommended for scenarios with severe contamination and high-level criteria of pollution control.
2024 Vol. 44 (10): 5696-5704 [Abstract] ( 134 ) [HTML 1KB] [ PDF 912KB] ( 756 )
Soil Pollution Control
5705 Adsorption/desorption and degradation of bisphenol A in soils from the water-level-fluctuation zone
HU Ying, SUN Jiao-xia, QIN Yan
To investigate the environmental behavior of bisphenol A (BPA) in the water-level-fluctuation zone (WLFZ), soil samples were collected at different elevations (SL: 155m, SM: 160m, SH: 165m) from the WLFZ in Qingxi Town, Fulin. Batch adsorption/desorption and simulated degradation experiments were conducted to study the adsorption, desorption, and degradation behaviors of BPA in these soil samples. At temperatures of 15℃, 25℃, and 35℃, the adsorption isotherms of BPA on soils at various elevations conformed to the Freundlich model, exhibiting decreased adsorption capacity with increasing temperature and showing non-linear adsorption characteristics. The adsorption capacity of BPA in soil samples followed a trend consistent with soil organic matter content, increasing as elevation decreased (SL > SM > SH). The values of calculated thermodynamic data ΔG、ΔH and ΔS were all less than zero, indicating that the adsorption of BPA in tested soils was a spontaneous, exothermic process with decreased entropy, dominated by physical adsorption. The desorption hysteresis index HI (0.853-0.981) approached 1, suggesting minimal desorption hysteresis and easy release of BPA from the soils. Under 25℃, the half-life of BPA degradation in soils followed the sequence SL (4.88d) < SM (6.68d) < SH (10.07d), indicating slower degradation rates in soils from long-term exposed areas. At 10℃, the half-life of BPA degradation in soil SH extended to 12.01d, which was 1.19 and 1.20 times longer compared to 25℃ and 35℃, respectively, indicating inhibition of BPA degradation under low-temperature conditions.
2024 Vol. 44 (10): 5705-5713 [Abstract] ( 140 ) [HTML 1KB] [ PDF 773KB] ( 778 )
5714 Investigation on the mechanism of intermittent stirring on the remediation of chromium-containing soil by digestate coupled with ferrous sulfate
XIAN Ying-zhuo, SHA Fu-jian, QIAN Yu-long, LI Xiao-cai, LI Rong-qiang, SUN Ying-jie, ZHANG Da-lei, ZHAO Jian-wei
The effect of intermittent stirring on the remediation of Cr(VI)-containing soil via digestate coupled with ferrous sulfate was investigated. Speciation changes of chromium (Cr),sulfur (S) and iron (Fe), during the process were examined through X-ray Photoelectron Spectroscopy (XPS). Finally, complemented by microbial community analysis, the mechanism was elucidated. The results indicated that intermittent stirring significantly accelerated the reaction compared to static incubation. Non-detectable Cr(VI) in soil with initial Cr(VI) content of 3000mg/kg could be achieved within 2 days. The sulfate reduction was higher under intermittent stirring, accompanied with an increase of S2- content. Microbial community analysis showed that Cr(VI)-tolerant bacteria was activated after intermittent stirring treatment with a higher relative abundance of chromium-reducing and sulfate-reducing bacteria. Overall, intermittent stirring enhances Cr(VI) reduction efficiency, promoted sulfate reduction, and positively impacts microbial community structure, offering a promising approach for the low-carbon and efficient treatment of Cr(VI)-contaminated sites.
2024 Vol. 44 (10): 5714-5722 [Abstract] ( 113 ) [HTML 1KB] [ PDF 1881KB] ( 734 )
5723 Isolation of a high-efficient diesel degrading bacteria and its degradation of alkane components of diesel
CHEN Hong-chu, ZHANG Ting-di, FU Yu-feng, RU Jin-tao, QIN Chuan-yu
A diesel degrading bacterial strain 13-3isolated from oil-contaminated soil in an oilfield mining area in Northeast China was identified as Acinetobacter sp. by morphological observation and 16S rRNA. The strain could degrade 88.50% diesel of 1g/L cultured at 20℃ at 180r/min for 7days, which showed excellent diesel degrading ability compared with other strains, and the degradation rate of diesel fuel could reach 71.7% after being inoculated into 10g/kg diesel contaminated soil and remediation at 20℃ and soil moisture content of 30% for 21days, which indicated it had great potential in practical diesel-contaminated soil remediation applications. According to the analysis of GC-MS spectrum and the degrading experiments of different chain length alkane substrates, strain 13-3had a wide alkane utilization spectrum (C14~C22), and the degradation rate of C17~C20 could reach more than 90%. The results of environmental factors showed that strain 13-3could grow in the range of pH=6~9, temperature 10~30℃, salinity (NaCl) 0.5%~3%, and still had a high concentration of bacterial solution at the initial diesel concentration of 10g/L, which indicated that strain 13-3 had good environmental adaptability and was expected to exert its degradation performance under complex environmental conditions. Through whole-genome sequencing analysis, three key genes (alkB, almA, ladA) were found in the genome of strain 13-3, and the possible degradation pathway of strain 13-3 was speculated to be the terminal oxidation pathway.
2024 Vol. 44 (10): 5723-5732 [Abstract] ( 100 ) [HTML 1KB] [ PDF 1160KB] ( 617 )
5733 Quantifying the uncertainty of farmland soil actual denitrification potential as determined by the acetylene inhibition method
CAO Wen-chao, WANG Ya-jing, LI Yan-qing, PAN Hao-qin, ZHAO Fei, XIAO Wan-Li, WANG Cui-cui, WANG Jing-guo, SONG He
This study employed an anaerobic slurry incubation test to evaluate whether the acetylene inhibition method may have led to an underestimation of the denitrification potential in both greenhouse vegetable and grain field soils, using a robotized sampling and analysing system. Soils from greenhouse vegetable fields and adjacent grain fields in the Shouguang region were sampled. The treatments with and without the addition of 10% acetylene were set up respectively. The results showed that the accumulated N2O concentration in the 10% acetylene treatment was significantly higher than those without acetylene after 3hours of anaerobic slurry incubation, while N2 accumulation showed the opposite trend. Moreover, in the presence of acetylene, 7.92% and 34.2% of N2O were reduced to N2 in greenhouse vegetable and grain field soils, respectively, within 63 hours of anaerobic incubation. The actual denitrification potential significantly increased with the addition of 10% acetylene in the greenhouse vegetable and grain field soils, but the respiration of the soils was not significantly affected. Specifically, the acetylene inhibition method overestimated the actual denitrification potential in greenhouse vegetable soil by 22.0%, and underestimated it in grain field soil by 11.4%, as determined by the bias calculated from the acetylene inhibition method (AIT-bias). Overall, the acetylene inhibition method was found to be insufficient in completely suppressing N2O reduction to N2 in greenhouse vegetable and grain field soils. The uncertainty of acetylene inhibition method on the actual denitrification potential of soil is profoundly influenced by the cropping system, which may be related to variations in soil nutrients, types and other factors. Further research is necessary to assess the reliability of this method across different soil conditions.
2024 Vol. 44 (10): 5733-5742 [Abstract] ( 115 ) [HTML 1KB] [ PDF 874KB] ( 593 )
5743 Adsorption and degradation of chlorinated alkanes in landfill cover soil: insights into soil microecology and metabolic dynamics
XING Zhi-lin, LI Liang-jie, WANG Yong-qiong, CHEN Shang-jie
The vegetation community composition of a landfill in Chongqing was comprehensively investigated for three consecutive years. The results indicated significant differences in the adsorption of chlorinated alkanes by rhizosphere soils from different vegetation. The adsorption amounts of DCM, CF, and CT in the rhizosphere soils were 1.0~5.14mg/gsoil, 0.7~3.1mg/gsoil, and 0.32~3.3mg/gsoil, respectively, with the maximum adsorption being more than three times that of bare soil. Among the vegetation, Rumex and Cynodon dactylon exhibited the highest adsorption of DCM, while Limonium sinuatum and Miscanthus floridulus had the strongest adsorption of CF. The adsorption of chlorinated alkanes by most vegetation rhizosphere soils conformed to the Freundlich model. The results of the biodegradation experiment showed that rhizosphere soils significantly enhanced the biotransformation of CH4, DCE, and CF by soil microorganisms, with enhancement factors reaching up to 20, 6, and 7times compared to bare soil. The oxidation rates of all rhizosphere soils showed significant differences from bare soil, with Rumex, Artemisia, and Amaranthus exhibiting the best degradation enhancement. Diversity analysis revealed that the microbial richness in most rhizosphere soils was significantly higher than that in bare soil, and the microbial community structure in different rhizosphere soils varied significantly. The rhizosphere effect induced a shift in dominant methanotrophs from Methylophilaceae to Methylocicrobium, Methylomonadaceae, Methylobacter, Methylobacillus, Methylocystis, and Methylococcus. Metabolomics analysis identified Neopetasitenine as a potential key player in enhancing microbial activity. Mechanistic analysis revealed that the enhanced biotransformation capacity of chlorinated alkanes remained crucial for their reduction.
2024 Vol. 44 (10): 5743-5756 [Abstract] ( 133 ) [HTML 1KB] [ PDF 3078KB] ( 739 )
5757 Effects of nitrogen deposition and precipitation changes on the soil ammonia-oxidizing bacteria community in desert steppe
ZHAO Yu, YE He, WU Zhen-dan, YUE Mei, HUANG Li-dong, TU Na-re, SHANG Xing-ling, LI Shuo, HUANG Kai-chun, HONG Mei
To explore the effects of nitrogen deposition and precipitation changes on the soil ammonia-oxidizing bacteria (AOB) community, we conducted a split-plot experiment in a desert steppe dominated by Stipabreviflora. The main plots include three water regimes: natural rainfall (CK), a 30% increase in rainfall (W), and a 30% decrease in rainfall (R). The subplots were treated with four nitrogen levels: 0 (N0/CK), 30 (N30), 50 (N50), and 100 (N100) kg/(hm2·a). High-throughput sequencing was utilized to assess the diversity and composition of the soil AOB community. Our findings revealed that the dominant AOB in the desert steppe soils are norank_d__Bacteria, unclassified_k__norank_d__Bacteria, and the genus Nitrosospira. Under natural rainfall conditions, the AOB-amoA gene copy number increased with higher nitrogen application. However, in the reduced rainfall treatment, the AOB-amoA gene copy number significantly rose at the N50 level but sharply declined at the N100 level, suggesting that N50 is a threshold for soil AOB abundance in the desert steppe. Furthermore, higher alpha diversity was associated with increased rainfall. Significant differences in soil AOB community structure across the various nitrogen treatments were revealed by principal coordinate analysis. Redundancy analysis identified soil moisture content, nitrate nitrogen, ammonium nitrogen, and total nitrogen as the key environmental factors driving changes of the soil AOB community.
2024 Vol. 44 (10): 5757-5765 [Abstract] ( 104 ) [HTML 1KB] [ PDF 1385KB] ( 696 )
Environmental Ecology
5766 Distribution characteristic and its influencing factors of branched tetraether lipids in water columns of Lake Fuxian
TIAN Xiao-qing, ZHANG Hu-cai, SUN Hui-ling
Here we analyze an annual cycle of brGDGTs distribution and abundances in the water column (0~100m) of Lake Fuxian and its influencing factors, including water temperature (WT), dissolved oxygen (DO) and pH values, based on samples of soils, lacustrine surface sediments and suspended particulate matter (SPM) of water columns from an oligotrophic deep lake-Lake Fuxian in southwestern China. The aim of our research is to explore the response of brGDGTs distribution to the dynamic changes of environmental factors in Lake Fuxian from the perspective of real-time observation, to better discriminate the reliability of brGDGTs-based reconstructed palaeotemperatures. The results show that brGDGTs in water column are mainly in-situ production, while brGDGTs contributions from soil and river are quite weak. There is an obvious thermocline and oxycline at a water depth of 40m in Lake Fuxian.The total concentrations of brGDGTs covary with the phytoplankton biomass seasonally. The concentrations of brGDGTs compounds covary with vertical depth and time as well, especially 6-Methyl brGDGTs reaching its maximum in hypolimnion. There is a strong correlation between brⅢa’, MBT’, MBT’6ME and DO, indicating that DO influences the distribution of brGDGTs by influencing 6-methyl brGDGTs. The dynamic variations of DO in water column play an important role in the distribution of bacterial-derived brGDGTs in Lake Fuxian.
2024 Vol. 44 (10): 5766-5775 [Abstract] ( 128 ) [HTML 1KB] [ PDF 1443KB] ( 533 )
5776 Studies on the migration, transformation and accumulation pattern of nitrogen and phosphorus in the vadose zone of coral islands
LI Li, ZHANG Pan, ZHAO Zhi-wei, ZHANG Sai, GONG Xing, XU Ting-hao
The migration and transformation of nitrogen and phosphorus in the vadose zone of coral islands have a direct impact on the groundwater quality and soil structure of the islands. Through XRD and SEM analyses, the unique CaCO3phase composition and porous morphology of coral sand were elucidated. Static adsorption experiments were conducted to clarify the adsorption mechanism of N and P in coral sand; short-term continuous rainfall simulation column experiments were used to investigate the transport mechanism of N and P in coral sand, while long-term intermittent rainfall simulation column experiments examined the N transformation and P accumulation in different depth profiles. The results showed that the average adsorption amounts of NH4+ and DIP in coral sand were 192mg/kg and 2051.75mg/kg, respectively, with adsorption models conforming to reversible linear adsorption and Freundlich isothermal adsorption models. The transport mechanism of NH4+ was explicable by the linear equilibrium CDE model, while the transport process of low-concentration DIP followed a two-point chemical nonequilibrium model with an attenuation term. The transport of high-concentration DIP could not be modeled, and a dissolution and precipitation equilibrium reaction with CaCO3 was speculated in conjunction with the pH value. Under long-term rainfall conditions, microbial analysis indicated a nitrogen pathway N2→NH4+→NO2-→NO3-→N2/DON in the soil, posing a risk of nitrogen contamination to groundwater. Meanwhile, DIP was fixated in the form of insoluble phosphorus, potentially negatively impacting soil structure through long-term accumulation. In conclusion, the unique characteristics of N and P migration, transformation, and accumulation in the vadose zone of coral islands provide a scientific basis for environmental risk management in island ecological development.
2024 Vol. 44 (10): 5776-5787 [Abstract] ( 110 ) [HTML 1KB] [ PDF 2682KB] ( 778 )
5788 Terpenoid-induced algal inhibition and the co-culture of terpene-enriched plants for algal suppression
JIANG Yu-meng, ZHANG Wen-le, LUO Zhao-hui, LI Hui-xin, CHEN Dan
In order to solve the problem of cyanobacteria bloom in freshwater bodies in summer, Microcystis aeruginosa was taken as the research object, and six terpenoid compounds including menthol, borneol, geraniol, andrographolide, linalool and citral were selected to screen high-efficiency algaecides, and their algaecological effects, mechanisms, application methods and ecological safety were explored. The results showed that geraniol and citral had the best inhibitory effects on Microcystis aeruginosa, and the inhibition rate increased with the increase of concentration. At a concentration of 60mg/L, The maximum inhibition rates of geraniol and citral were 86.9% and 76.0%, respectively. Under the action of geraniol and citral, the chlorophyll a and carotenoid contents of Microcystis aeruginosa decreased, photosynthesis was inhibited; the activity of antioxidant enzymes decreased, and reactive oxygen accumulated in cells; free radicals attacked the cell membrane, and the cell structure was damaged, leading to the death of algal cells. Geraniol and citral did not have the properties of "low promotion and high inhibition". They were less toxic to Chlamydomonas and Brachionus calyciflorus, and had no significant effect on Elodea and Zebrafish, and had a certain ecological safety. Geraniol-rich Melissa officinalis and citral-rich Citronella showed significant algal inhibition in co-culture with Microcystis aeruginosa with algal inhibition rate as high as 95%, which is suitable to be used as floating-bed plants for the prevention and control of cyanobacterial blooms.
2024 Vol. 44 (10): 5788-5800 [Abstract] ( 116 ) [HTML 1KB] [ PDF 1068KB] ( 903 )
5801 Review on the control of algal blooms via artificial mixing: theory, technologies and mechanism
WEN Cheng-cheng, DONG Zhi-long, LI Kai, LI Nan, WANG Bao-shan, WEN Gang, HUANG Ting-lin, XIAO Cai-wei
Artificial mixing influences the algal growth and structure by regulating hydrodynamic conditions, which has been applied to control the algal blooms in the global lakes and reservoirs for many years. The related researches at home and abroad have been widely reported, but the systematic review is rare. Especially, due to the limited understanding of the application precondition, application conditions, and advantages and disadvantages of different technologies, these technologies were misused and did not play its advantages, which resulted in the poor and even ineffective effect on algal control. The main conclusions includes: (1) Artificial mixing controls the change of algal biomass and structure by regulating mixing depth (Zmix), whose application effect is mainly related to the water depth, horizontal distribution of mixing devices, system operation regimes, and mixing efficiency; (2) The algal control period (i.e., the reduction of more than 95% of algal cell density) of Artificial mixing is about 2weeks, and the recommended Zmix threshold for algal control is more than 15m; (3) Artificial mixing is mainly suitable for the deep waters, and the selection of algal control technologies should consider their application conditions, cost effectiveness and so on.
2024 Vol. 44 (10): 5801-5817 [Abstract] ( 104 ) [HTML 1KB] [ PDF 2960KB] ( 995 )
5818 Hydrogeochemical mechanism and irrigation suitability of groundwater in the plain area of Turpan Basin
DING Qi-zhen, ZHOU Yin-zhu, ZHOU Jin-long, SUN Ying, HAN Shuang-bao, JIANG Feng, LIN Jin-wei
In the plain area of Turpan Basin in Xinjiang, 52 groundwater samples and 7surface water samples were collected for qualitative and quantitative analysis of the source of groundwater solute and the influencing factors of hydrochemistry and evaluation of irrigation water quality using the methods of hydrochemistry, hydrogen and oxygen stable isotopes, forward model (FM) and factor analysis. Shallow groundwater in the northern Turpan Basin was neutral to weak alkaline, while shallow groundwater and deep groundwater in the southern Turpan Basin were weak alkaline, and that the dominant anions and cations were SO42- and K++Na+, respectively; atmospheric precipitation was the main source of groundwater recharge in the study area. Compared with the shallow groundwater in the northern Turpan Basin and the deep groundwater in the southern Turpan Basin, part of the shallow groundwater in the southern Turpan Basin was affected by evaporation-concentration to a certain extent; the source of groundwater solute was mainly controlled by rock weathering, mainly evaporite rock. Relative contributions of river input, human activities and rock weathering to shallow groundwater in the northern Turpan Basin, shallow groundwater in the southern Turpan Basin and deep groundwater in the southern Turpan Basin were (10.23%, 1.25%, 88.52%), (10.72%, 0.66%, 88.62%) and (5.30%, 0.44%, 94.26%), respectively; the hydrochemistry of shallow groundwater in the southern and northern Turpan Basin was mainly affected by leaching-evaporation (54.31%) and agricultural activities-organic matter content (35.36%), while leaching (58.96%) and environmental condition (28.97%) were the main controlling factors of deep groundwater hydrochemistry in the southern Turpan Basin; deep groundwater in the southern Turpan Basin was generally suitable for irrigation. However, shallow groundwater in the northern Turpan Basin was affected by high EC and that in the southern Turpan Basin was affected by high EC and % Na, which were not suitable for irrigation in partial areas.
2024 Vol. 44 (10): 5818-5829 [Abstract] ( 125 ) [HTML 1KB] [ PDF 3569KB] ( 713 )
5830 Numerical simulation of the hydrochemistry for surface water injection into deep karst geothermal reservoirs in baiyangdian
LI Sheng-tao, SHI Jin-yu, DING Xin-ming, YUE Dong-dong, LU Ying
Taking the extensively developed deep karst thermal reservoirs in Xiong'an New Area as the research object, this study uses PHREEQC to simulate the changes in hydrochemical components and the amounts of mineral dissolution and precipitation after injecting Baiyangdian surface water into the main exploited thermal reservoir—the Jixian Wumishan Formation karst thermal reservoir. According to the results, it can be seen that during the reinjection period, the chemical types of water from the reinjection well to the interior of the reservoir are sequentially HCO3•Cl-Na•Mg, HCO3•Cl-Na, Cl•HCO3-Na and Cl-Na types, showing a transition from supply water to original reservoir water. This trend is mainly affected by advection and dispersion, but Mg2+, Ca2+, HCO3- are also controlled by factors such as water-rock reactions and pH, resulting in more complex trends. The dissolution and precipitation of minerals after reinjection mainly occur within a radius of 0.5m from the reinjection well, with the most obvious precipitation of calcite and dissolution of dolomite. These mineral reactions lead to a slight decrease in fracture porosity overall, but the change is limited and does not significantly affect rock permeability. Based on the types of changes in the geothermal reservoir caused by reinjection, four impact zones were delineated, namely the chemical impact zone, the seepage impact zone, the temperature impact zone, and the rock permeability impact zone, with the size of each impact zone decreasing in the order listed above.
2024 Vol. 44 (10): 5830-5838 [Abstract] ( 123 ) [HTML 1KB] [ PDF 1478KB] ( 542 )
5839 Predicting dissolved N2O concentrations from drainage ditches in salt-affected farmlands
JI Jing-jing, SHE Dong-li, ALIMU Abulaiti, PAN Yong-chun
This study selected typical saline-alkali agricultural drainage ditches from the Qingtongxia Irrigation District in Ningxia as the subject of research. Based on key water quality parameters of the water body overlying the drainage ditches, including dissolved organic carbon (DOC), water temperature (WT), nitrate nitrogen (NO3--N), and electrical conductivity (EC), a backpropagation (BP) neural network predictive model for the dissolved concentration of Nitrous oxide (N2O) with optimized parameters was constructed. The model was further optimized using Genetic Algorithm (GA) and Ant Colony Optimization (ACO) to enhance the prediction accuracy and stability.The results indicate that an increase in EC significantly promotes the dissolved concentration of N2O in the water body overlying the drainage ditches. There is an extremely significant positive correlation between NO3--N and EC with the dissolved concentration of N2O, while WT and DOC show a significant negative correlation with the dissolved concentration of N2O. The effectiveness and reliability of the constructed model were verified using actual measured data of the dissolved concentration of N2O in the water body overlying the drainage ditches, with the correlation coefficient of the predicted values and actual measured values of the ACO-BP model all exceeding 0.70. Under the best conditions, the coefficient of determination (R2) reached 0.79, and the Mean Relative Error (MRE) was only 7.26%.
2024 Vol. 44 (10): 5839-5846 [Abstract] ( 119 ) [HTML 1KB] [ PDF 1840KB] ( 534 )
Emerging Contaminants and Environmental Toxicology
5847 Toxic effects of brominated flame retardants and insecticides on Scenedesmus obliquus
SHEN Hong-yan, LIU Xue-wei, LI Yan, LIU Ai-zhen, BIAN Yong-huan, YANG Jing-po, SUN Hao-yu, YANG Lei
In order to clarify the toxic effects of brominated flame retardants and insecticides on microalgae, the present study investigated the single and combined toxicity of three brominated flame retardants (BFRs), three neonicotinoid insecticides (NNIs), and three organophosphorus insecticides (OIs) to microalgae. The results showed that both single and mixed systems of BFRs, NNIs and QIs induced the hormetic effect in the form of promotion at low concentrations and inhibition at high concentrations in S. obliquus. The hormetic effect was closely related to intracellular reactive oxygen species (ROS) levels. A moderate growth in ROS level promoted the growth of microalgae and might even lead to the generation of bloom, while a significant growth in ROS inhibited the growth of microalgae. Predicting no-effect concentrations (PNECs) for all nine pollutants were within the lagged stimulus interval, suggesting that the PNEC values predicted by the dose-effect curves overestimated the risk of the pollutants to aquatic ecosystems. Based on the independent action model (IA), it was found that the combined toxicity of 18 binary mixing systems on S. obliquus had a concentration-dependent effect.
2024 Vol. 44 (10): 5847-5854 [Abstract] ( 98 ) [HTML 1KB] [ PDF 1279KB] ( 638 )
5855 The combined toxic effects of arsenic and perfluorooctanoic acid on the earthworm Eisenia fetida
NIU Xiao-yu, XUE Wei-na, LI Shuai, YANG Li-li, WANG Zhi-feng
Earthworms (Eisenia fetida) were exposed to sub-lethal doses of arsenate (As(V)), perfluorooctanoic acid (PFOA), and their mixture for 28 days to analyze the bioaccumulation of two toxins and to characterize the response of multiple biomarkers, thereby assessing the combined toxic effects of As(V) and PFOA. The results of bioaccumulation analyses showed that the coexistence of As(V) and PFOA in soil increased arsenic bioaccumulation while decreasing PFOA's bioaccumulation. As exposure levels increased, the majority of the biomarkers demonstrated significant alterations, indicating inhibition of earthworm growth and oxidative damage. The Integrated Biomarker Response Index (IBR) was utilized to summarize multiple biomarker responses, revealing significant dose-effect relationships in both the single and combined contamination groups of As(V) and PFOA. Subsequently, IBR was combined with two mixture toxicity indices, the Effect Addition Index (EAI) and the Concentration Addition Index (CAI), to assess the toxic interaction between As(V) and PFOA. The results indicated that the joint toxicity of As(V) and PFOA was dependent on the concentration of As(V). At higher concentrations of As(V), a synergistic interaction was observed across all effect levels. Conversely, at lower concentrations of As(V), the interaction shifted from antagonism to synergism as the exposure level increased. As(V) emerged as the primary toxicant, significantly impacting earthworm biomarkers and influencing the overall toxicity of the As(V)/PFOA mixture. These findings provide valuable insights for the risk assessment of the combined toxicity of As(V) and PFOA.
2024 Vol. 44 (10): 5855-5865 [Abstract] ( 117 ) [HTML 1KB] [ PDF 1291KB] ( 772 )
5866 Characterization of formation of disinfection by-products during chlor(am) ine disinfection of filamentous fungi
LI Xiang, WU Ge-hui, TIAN Shi-qi, WAN Qi-qi, HUANG Ting-lin, WEN Gang
This study investigated the formation patterns of disinfection by-products (DBPs) during the disinfection process using chlorine and chloramine as disinfectants. We focussed on three common filamentous fungi found in drinking water—Aspergillus niger, Aspergillus flavus, and Penicillium polonicum—along with Escherichia coli. The research revealed differences in DBP formation potential due to variations in cellular composition and reactivity with disinfectants. The order of microbial DBP formation potential was as follows: A. niger > A. flavus > P. polonicum > E. coli. The chlorine disinfection process yielded DBP concentrations of 73.4, 66.3, 47.7, and 27.0 μg/mgC for these microorganisms, while the chloramine process resulted in concentrations of 17.4, 14.5, 10.4, and 7.7μg/mgC, respectively. Notably, DBPs formed by Aspergillus species were primarily derived from cell walls during chlorine process, among the cell wall components of Aspergillus, melanin played a significant role in DBP formation, surpassing chitin and glucan, particularly in the case of haloacetic acids (HAAs). In contrast, DBPs formed by P. polonicum and bacteria predominantly originate from cellular contents, with their relative contributions less influenced by the disinfection method. Additionally, the type and concentration of DBPs formed by Aspergillus were influenced by disinfectant dosage, pH, temperature, and bromide ion concentration.
2024 Vol. 44 (10): 5866-5874 [Abstract] ( 103 ) [HTML 1KB] [ PDF 926KB] ( 797 )
5875 The distribution characteristics of three types of diarrheal pathogens in the lakes of Wuhan city
DENG Min, WANG Yu-ren, LIU Wen-jing, LI Lu, SONG Kang
Field surveys were conducted in Wuhan city and its surrounding areas to assess the water quality of urban and agricultural lakes during winter and summer. Additionally, fluorescence quantitative PCR technology was employed to analyze the distribution patterns of three diarrheal pathogens. The results revealed that the average abundance of Escherichia coli uidA gene [(1.86±1.15)×109 copies/100mL] and the Shigella dysenteriae ipaH gene [(2.20±1.54)×105 copies/100mL] in urban lakes was approximately 2- and 2.7-times higher, respectively, compared to agricultural lakes (P<0.05). However, no significant regional difference was observed in the abundance of Salmonella spp. between urban and agricultural lakes. During the summer, the abundance of the E. coli uidA gene [(3.75±1.48)×109 copies/100mL] in lake water was significantly higher compared to the winter [(1.45±1.07)×109copies/100mL] (P<0.01). Conversely, no significant seasonal difference was observed in the abundance of Salmonella spp. and S. dysenteriae in the lake water. The abundance of E. coli, an indicator of fecal contamination, showed a significant positive correlation with the presence of S. dysenteriae ipaH gene (P<0.0001). However, no significant linear relationship was found between the abundance of the E. coli uidA gene and the presence of the Salmonella spp. dam gene (P>0.05). In the lake water, the abundance of the E. coli uidA gene and the S. dysenteriae ipaH gene showed significant positive correlations with chlorophyll-a, total phosphorus, and ammonium nitrogen. Overall, sewage discharge and surface runoff have led to nutrient enrichment and a significant increase in the abundance of pathogenic microorganisms in urban lakes. In summer, higher levels of suspended particles, predominantly composed of algae, promote the attachment and growth of pathogenic bacteria like E. coli. To accurately reflect pathogenic bacterial contamination in water bodies and control biological risks, it is necessary to increase the variety of pathogenic bacteria monitored in environmental water.
2024 Vol. 44 (10): 5875-5884 [Abstract] ( 120 ) [HTML 1KB] [ PDF 1499KB] ( 447 )
Carbon Emission Control
5885 Spatial and temporal patterns of impact of transportation informatization on transportation carbon emissions in provinces along the Belt and Road in China
SHI Jing-jing, ZHAO Hong-xing, NIE Jiang-long, HE Rui-chun, LIU Ping
The administrative units of 17provinces along the Belt and Road in China were selected as basic spatial units. Firstly, the evaluation index system for transportation informatization along the Belt and Road from 2012 to 2022 was established. Secondly, a bivariate spatial correlation analysis was conducted to explore the relationship between transportation informatization and transportation carbon emissions. Lastly, a geographical detector was employed to investigate the spatial-temporal heterogeneity of the impact of transportation informatization on transportation carbon emissions. The results indicated varying levels of transportation informatization development among provinces along the Belt and Road, with more mature developments observed in external window regions and pioneering open areas, while relatively lagging in the Silk Road core area and strategic fulcrum regions. The bivariate spatial autocorrelation index ranged from 0.1917 to 0.4001, exhibiting an overall downward trend, with significance levels ranging from 0.008 to 0.060. High-high clusters were primarily distributed in pioneering open areas, low-low clusters in the Silk Road core area, and high-low clusters in external window regions and strategic fulcrum regions, with an increasing number of provinces falling into the latter category over time. The application of transportation informatization systems emerged as the dominant driving factor influencing the spatial differentiation pattern of overall transportation carbon emissions along the Belt and Road, with a maximum average determinant power of 0.53. Differences existed in the driving factors influencing spatial differentiation of transportation carbon emissions among different provinces, and there was strong synergy among these factors.
2024 Vol. 44 (10): 5885-5900 [Abstract] ( 103 ) [HTML 1KB] [ PDF 1973KB] ( 661 )
5901 Predicting and decoupling analysis of transportation peak carbon emissions in Guanzhong Plain urban agglomeration based on panel data modeling
TIAN Ze-yuan, DONG Zhi, DONG Zhi-yu, DONG Xiao-lin, ZHANG Jia-qi, TANG Jia-xing, XING Pan
Using data on carbon emissions from the transportation industry (CT) from 2007 to 2021, a random-effects model with Driscoll-Kraay standard errors was employed to fit the extended STIRPAT model and predict CT in the coming years. Then, the decoupling situation of the added value of the transportation industry (TGDP) and CT was analyzed with a decoupling model during 2007 to 2035. The results indicated that transportation energy intensity, TGDP, and private vehicle ownership were the main factors driving CT growth in the Guanzhong Plain urban agglomeration; On the contrary, the proportion of renewable electricity and the intensity of transport fixed assets investment posed negative effects on CT, of which the proportion of renewable electricity was the main inhibitory factor. The CT reached its peak by 2030 based on the low-carbon scenario. The decoupling e value between CT and TGDP fluctuated between -0.62 and 3.01 from 2007 to 2013, then stabilized, primarily indicating weak decoupling. A strong decoupling between CT and TGDP was achieved after 2030. Overall, the study suggests optimizing the energy structure by increasing the proportion of renewable energy and controlling private vehicle ownership to achieve the transportation “emission peak” goal on schedule in the Guanzhong Plain urban agglomeration.
2024 Vol. 44 (10): 5901-5911 [Abstract] ( 93 ) [HTML 1KB] [ PDF 1333KB] ( 833 )
5912 Studies on the potential of inorganic carbon removal and carbon sequestration in seawater through Ca2+ addition
LI Shuo-chen, LI Xue-gang, HE Zhi-peng, SONG Jin-ming, LIU Shan-shan, WANG Zhi-bo
This study explored the potential of introducing Ca2+ into seawater to remove dissolved inorganic carbon and enhance the oceanic carbon sink. Laboratory simulations under various initial conditions were conducted, by altering the initial pH of seawater, Mg/Ca ratio, and introducing seeding nuclei, monitor the changes in seawater pH, DIC, and TA regularly. Results indicated that the introduction of Ca2+ effectively reduced the magnesium-to-calcium ratio(5.2) in natural ocean and increased the oversaturation of calcium carbonate, thereby facilitating the removal of inorganic carbon from the marine system. Furthermore, the efficacy of inorganic carbon removal with calcium-containing compounds was positively correlated with the initial pH of seawater. However, solely elevating seawater pH was insufficient to induce calcium carbonate formation; additional Ca2+ introduction was necessary to enhance calcium carbonate oversaturation for significant inorganic carbon removal. Additionally, the study revealed that inducing non-homogeneous precipitation through the addition of specific nuclei further promotes calcium carbonate generation, thereby improving inorganic carbon removal from seawater.The research findings indicated that under the conditions of adding 45mmol/L of Ca2+ and montmorillonite nuclei, with an initial pH of 8.5, the maximum amount of calcium carbonate generated can reach 959 μmol/L. The removal of inorganic carbon from seawater, leading to the short-term absorption of atmospheric CO2and increased oceanic carbon sink, offers a novel perspective and theoretical foundation for exploring ocean carbon enhancement technologies.
2024 Vol. 44 (10): 5912-5920 [Abstract] ( 120 ) [HTML 1KB] [ PDF 1192KB] ( 669 )
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