Key Laboratory of Environmental Engineering, Shaanxi Province, Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China
In order to explore the influence of biological sludge return on performance of the mainstream system after chemical phosphate precipitation in the side-stream, phosphorus, nitrogen and organic matter removal, pathway of biological phosphorus removal and sludge sedimentation of the whole system after 85days of side-stream chemical phosphorus recovery with the sludge returned to anoxic tank in the A2/O system were investigated. The results showed that the phosphorus removal of the system could be improved at the beginning of the operation, the concentration of soluble phosphate in effluent was (0.07±0.04) mg/L; After 20 days' operation, the sludge settling performance became worse, and the phosphorus removal performance deteriorated, but the nitrogen and the organic matter removal performance were not significantly affected. The rate of anaerobic phosphorus release and aerobic phosphorus uptake decreased, but the rate of anoxic phosphorus uptake increased. The phosphorus removal ratio of anoxic denitrifying phosphate accumulation to aerobic phosphate accumulation increased from 43.20% to 53.38%, so the denitrifying phosphorus removal was strengthened. The metabolic patterns of PHA and glycogen of microorganism in the sludge were not changed, but the amount of PHA synthesized in anaerobic stage decreased gradually. The maximum recovery amount of phosphorus by side-stream accounted for 24.75% of that in the influent, which achieved considerable phosphorus recovery. When the system collapsed, the side-stream chemical phosphorus recovery was stopped for a short period, the functions of the system were gradually restored, and the continuous operation of the system could be realized in result.
Cordell D, Rosemarin A, Schröder J J, et al. Towards global phosphorus security:a systems framework for phosphorus recovery and reuse options[J]. Chemosphere, 2011,84(6):747-758.
Kerrn-Jespersen J P, Henze M. Biological phosphorus uptake under anoxic and aerobic conditions[J]. Water Research, 1993,27(4):617-624.
[5]
Jetten M S M, Horn S J, Loosdrecht M C M V. Towards a more sustainable municipal wastewater treatment system[J]. Water Science & Technology, 1997,35(9):171-180.
Heinzmann B, Engel G. Phosphorus Recycling in Treatment Plants with Biological Phosphorus Removal[J]. Water Science & Technology A Journal of the International Association on Water Pollution Research, 2004,52(10/11):543-548.
[8]
Loosdrecht M C M V, Brandse F A, Vries A C D. Upgrading of waste water treatment processes for integrated nutrient removal-The BCFS® process[J]. Water Science & Technology, 1998,37(9):209-217.
[9]
Van R P, Musvoto E V, Wentzel M C, et al. Modelling multiple mineral precipitation in anaerobic digester liquor[J]. Water Research, 2003,37(13):3087-3097.
Wang Z, Meng Y, Fan T, et al. Phosphorus removal and N2O production in anaerobic/anoxic denitrifying phosphorus removal process:long-term impact of influent phosphorus concentration[J]. Bioresource Technology, 2015,179:585-594.
[17]
Kuba T, Loosdrecht M C M V, Heijnen J J. Phosphorus and nitrogen removal with minimal COD requirement by integration of denitrifying dephosphatation and nitrification in a two-sludge system[J]. Water Research, 2016,30(7):1702-1710.
Wachtmeister A, Kuba T, Loosdrecht M C M V, et al. A sludge characterization assay for aerobic and denitrifying phosphorus removing sludge[J]. Water Research, 1997,31(3):471-478.
Barat R, Loosdrecht M C M V. Potential phosphorus recovery in a WWTP with the BCFS® process:Interactions with the biological process[J]. Water Research, 2006,40(19):3507-3516.
