Effects of Al3+ on pollutant removal and extracellular polymeric substances (EPS) under anaerobic, anoxic and oxic conditions
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Aluminum ions produced by aluminum mining, electrolytic industry and aluminum-based coagulants can enter wastewater treatment plants and interact with activated sludge. They can subsequently contribute to the removal of suspended solids and affect activated sludge flocculation, as well as nitrogen and phosphorus removal. In this study, the effects of Al3+ on pollutant removal, sludge flocculation and the composition and structure of extracellular polymeric substances (EPS) were investigated under anaerobic, anoxic and oxic conditions. Results demonstrated that the highest chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies were detected for an Al3+ concentration of 10 mg/L. In addition, the maximal dehydrogenase activity and sludge flocculation were also observed at this level of Al3+. The highest removal efficiency of total phosphorus (TP) was achieved at an Al3+ concentration of 30 mg/L. The flocculability of sludge in the anoxic zone was consistently higher than that in the anaerobic and oxic zones. The addition of Al3+ promoted the secretion of EPS. Tryptophan-like fluorescence peaks were detected in each EPS layer in the absence of Al3+. At the Al3+ concentration of 10 mg/L, fulvic acid and tryptophan fluorescence peaks began to appear, while the majority of protein species and the highest microbial activity were also detected. Low Al3+ concentrations (< 10 mg/L) could promote the removal efficiencies of COD and TN, yet excessive Al3+ levels (>10 mg/L) weakened microbial activity. Higher Al3+ concentrations (>30 mg/L) also inhibited the release of phosphorus in the anaerobic zone by reacting with PO43−.
KeywordsExtracellular polymeric substances Activated sludge Aluminum ion A2O Wastewater
This research was financially supported by the National Natural Science Foundation of China (Grant Nos. 51678119 and 51808254), the Science and Technology Development Program of Jilin Province (Nos. 20180201016SF and 20180101079JC) and the Scientific Research Foundation from Education Department of Jilin Province (Nos. JJKH20180453KJ and JJKH20180454KJ).
- Hudson N, Baker A, Ward D, Reynolds D M, Brunsdon C, Carliell-Marquet C, Browning S (2008). Can fluorescence spectrometry be used as a surrogate for the Biochemical Oxygen Demand (BOD) test in water quality assessment? An example from South West England. Science of the Total Environment, 391(1): 149–158CrossRefGoogle Scholar
- Lin J X, Jiang X, Cao J S, Fang F, Feng Q (2018). Influences of phosphorous removal chemicals on EBPR system in wastewater treatment. Water Purification Technology, 37(12): 84–90 (in Chinese)Google Scholar
- Nie Y L, Tian X K, Zhou Z X, Li Y Y (2017). Impact of food to microorganism ratio and alcohol ethoxylate dosage on methane production in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor. Frontiers of Environmental Science and Engineering, 11(6): 6CrossRefGoogle Scholar
- Salama Y, Chennaoui M, Sylla A, Mountadar M, Rihani M, Assobhei O (2016). Characterization, structure, and function of extracellular polymeric substances (EPS) of microbial biofilm in biological wastewater treatment systems: A review. Desalination and Water Treatment, 57(35): 16220–16237CrossRefGoogle Scholar
- Wang S Y, He Y L, Li X Y, Jia F X, Guo S Y (2016). Optimization of extracellular polymeric substance extraction method of different sludge. Journal of Beijing University of Technology, 42(4): 569–576 (in Chinese)Google Scholar
- Yang T, Hao X K, Chen B Y, Chen Y X, Zhang Y, Yang K (2018). Effects of Al3+ on dehydrogenase activity (DHA) and extracellular polymeric substances (EPS) of activated sludge in a sequencing batch biofilm reactor (SBBR). Acta Scientiae Circumstantiae, 38(4): 1453–1459 (in Chinese)Google Scholar