Effects of persulfate oxidation on dewatering performance and removing heavy metals in municipal sludge
ZHANG Wei-ning1, XIAO Zhi-hua2, Ma Bin1, ZENG Qing-ru1,2
1. College of Resources and Environment, Human Agricultural University, Changsha 410128, China; 2. Rural Ecosystem Health Laboratory of Hunan Dongting Lake Area, Human Agricultural University, Changsha 410128, China
Abstract：The objectives of the study were to investigate the effects of the strong oxidizing agent-potassium persulfate on heavy metal removal, dewatering performance and characteristic of sludge. The results showed that sludge dewatering performance was improved, the moisture content of sludge cake was decreased from 82.6% to 74.8%, specific cake resistance was reduced from 6.70×108S2/g to 5.43×108S2/g under the condition (2for initial pH, 1h for reaction time, 25℃ for temperature, 1.34g/g SS for K2S2O8 dosage). K2S2O8 could effectively promote decomposition of the sludge floc. As a result, COD in the sludge supernatant was increased from 15.2mg/L to 187.0mg/L, TN in the sludge supernatant was increased from 6.03mg/L to 22.7mg/L, TP in the sludge supernatant was increased from 8.15mg/L to 12.7mg/L, and TSS in the sludge supernatant was decreased by 9.4%.The removal rates of tested heavy metals increased with increasing oxidant concentration, when the dosage of K2S2O8 was 2.01g/g SS, the removal rates of Pb, Zn, Cu and Cd in sludge could reach 63.90%, 87.10%, 86.40% and 84.25%, respectively. The removal rates of heavy metals had been basically stable when the dosage was greater than 2.01g/g SS. However, the efficiency of removal could increase with decreasing pH within a certain range. The heavy metals in the sludge were transferred to the supernatant after K2S2O8 oxidation. Then, calcium oxide of 0.075% concentrations was added to the supernatant, the pH value in the supernatant increased, as a result, the contents of heavy metals could be removed by 16.95% for Pb, 54.70% for Zn, 58.90% for Cu, and 21.95% for Cd in supernatant, respectively, the TN and TP in the liquid could be obviously improved.
张维宁, 肖智华, 马彬, 曾清如. 过硫酸盐对城市污泥脱水和重金属去除的影响[J]. 中国环境科学, 2017, 37(12): 4605-4613.
ZHANG Wei-ning, XIAO Zhi-hua, Ma Bin, ZENG Qing-ru. Effects of persulfate oxidation on dewatering performance and removing heavy metals in municipal sludge. CHINA ENVIRONMENTAL SCIENCECE, 2017, 37(12): 4605-4613.
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