Abstract
In the published literature, deflocculation of aerobic biological flocs under low dissolved oxygen (DO) () conditions is typically reported as occurring as early as after 1 h of oxygen deficiency. However, results of this study involving aerobic sludge from three different sources repeatedly indicated a lack of deflocculation after 24 h of low DO conditions. This finding has led to the conclusion that low DO might not be a direct cause of deflocculation. In addition to the low DO conditions, the sludge samples were not re-fed throughout the experiment, but deflocculation was still not observed. An analysis of the soluble microbial products (SMP) and loosely and tightly bound extracellular polymeric substances (EPS) was performed to improve understanding of the sludge’s behavior in response to low DO conditions. Results indicated no increase in SMP content or change in the tightly bound EPS content upon extended periods of low DO. It was concluded that high proteins concentration in the bound EPS improved flocs stability, and so contributed to the maintenance of floc integrity during extended periods of low DO conditions.
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Acknowledgments
This project was supported by funding from Grundfos Holdings through project Understanding and Mitigation of Sludge Deflocculation During Nitrogen Removal Process.
References
Bastviken, D., L. Persson, G. Odham, and L. Tranvik. 2004. “Degradation of dissolved organic matter in oxic and anoxic lake water.” Limnol. Oceanogr. 49 (1): 109–116. https://doi.org/10.4319/lo.2004.49.1.0109.
Basuvaraj, M., J. Fein, and S. N. Liss. 2015. “Protein and polysaccharide content of tightly and loosely bound extracellular polymeric substances and the development of a granular activated sludge floc.” Water Res. 82: 104–117. https://doi.org/10.1016/j.watres.2015.05.014.
Chen, J., E. J. LeBoeuf, S. Dai, and B. Gu. 2003. “Fluorescence spectroscopic studies of natural organic matter fractions.” Chemosphere 50 (5): 639–647. https://doi.org/10.1016/S0045-6535(02)00616-1.
DuBois, M., K. A. Gilles, J. K. Hamilton, P. A. Rebers, and F. Smith. 1956. “Colorimetric method for determination of sugars and related substances.” Anal. Chem. 28 (3): 350–356. https://doi.org/10.1021/ac60111a017.
Eaton, A. D., L. S. Clesceri, M. A. H. Franson, A. P. H. Association, A. E. Greenberg, E. W. Rice, A. W. W. Association, and W. E. Federation. 2005. Standard methods for the examination of water & wastewater. Standard Method 2540 B and E. Washington, DC: American Public Health Association.
Faust, L., H. Temmink, A. Zwijnenburg, A. J. Kemperman, and H. H. Rijnaarts. 2014. “Effect of dissolved oxygen concentration on the bioflocculation process in high loaded MBRs.” Water Res. 66: 199–207. https://doi.org/10.1016/j.watres.2014.08.022.
Frolund, B., T. Griebe, and P. H. Nielsen. 1995. “Enzymatic-activity in the activated-sludge floc matrix.” Appl. Microbiol. Biotechnol. 43 (4): 755–761. https://doi.org/10.1007/BF00164784.
Gamar-Nourani, L., K. Blondeau, and J. Simonet. 1998. “Influence of culture conditions on exopolysaccharide production by Lactobacillus rhamnosus strain C83.” J. Appl. Microbiol. 85 (4): 664–672. https://doi.org/10.1111/j.1365-2672.1998.00574.x.
Guo, X., X. Wang, and J. Liu. 2016. “Composition analysis of fractions of extracellular polymeric substances from an activated sludge culture and identification of dominant forces affecting microbial aggregation.” Sci. Rep. 6: 28391. https://doi.org/10.1038/srep28391.
Higgins, M. J., and J. T. Novak. 1997. “The effect of cations on the settling and dewatering of activated sludges: Laboratory results.” Water Environ. Res. 69 (2): 215–224. https://doi.org/10.2175/106143097X125371.
Hou, W., Z. Ma, L. Sun, M. Han, J. Lu, Z. Li, O. A. Mohamad, and G. Wei. 2013. “Extracellular polymeric substances from copper-tolerance Sinorhizobium meliloti immobilize .” J. Hazard. Mater. 261 (Oct): 614–620. https://doi.org/10.1016/j.jhazmat.2013.06.043.
Jorand, F., F. Boue-Bigne, J. C. Block, and V. Urbain. 1998. “Hydrophobic/hydrophilic properties of activated sludge exopolymeric substances.” Water Sci. Technol. 37 (4–5): 307–315. https://doi.org/10.2166/wst.1998.0652.
Jørgensen, N. O. G. 2009. “Organic nitrogen.” In Encyclopedia of inland waters, edited by G. E. Likens, 832–851. Oxford, UK: Academic Press.
Li, H., Y. Wen, A. Cao, J. Huang, and Q. Zhou. 2014. “The influence of multivalent cations on the flocculation of activated sludge with different sludge retention times.” Water Res. 55: 225–232. https://doi.org/10.1016/j.watres.2014.02.014.
Li, H. S., Y. Wen, A. S. Cao, J. S. Huang, Q. Zhou, and P. Somasundaran. 2012. “The influence of additives (, , and ) on the interaction energy and loosely bound extracellular polymeric substances (EPS) of activated sludge and their flocculation mechanisms.” Bioresour. Technol. 114: 188–194. https://doi.org/10.1016/j.biortech.2012.03.043.
Li, X. Y., and S. F. Yang. 2007. “Influence of loosely bound extracellular polymeric substances (EPS) on the flocculation, sedimentation and dewaterability of activated sludge.” Water Res. 41 (5): 1022–1030. https://doi.org/10.1016/j.watres.2006.06.037.
Liu, X.-M., G.-P. Sheng, H.-W. Luo, F. Zhang, S.-J. Yuan, J. Xu, R. J. Zeng, J.-G. Wu, and H.-Q. Yu. 2010. “Contribution of extracellular polymeric substances (EPS) to the sludge aggregation.” Environ. Sci. Technol. 44 (11): 4355–4360. https://doi.org/10.1021/es9016766.
Liu, Y., and H. H. P. Fang. 2003. “Influences of extracellular polymeric substances (EPS) on flocculation, settling, and dewatering of activated sludge.” Crit. Rev. Environ. Sci. Technol. 33 (3): 237–273. https://doi.org/10.1080/10643380390814479.
Lowry, O. H., N. J. Rosebrough, A. L. Farr, and R. J. Randall. 1951. “Protein measurement with the Folin phenol reagent.” J. Biol. Chem. 193 (1): 265–275.
Mei, X. J., Z. W. Wang, X. Zheng, F. Huang, J. X. Ma, J. X. Tang, and Z. C. Wu. 2014. “Soluble microbial products in membrane bioreactors in the presence of ZnO nanoparticles.” J. Membr. Sci. 451: 169–176. https://doi.org/10.1016/j.memsci.2013.10.008.
Morgan-Sagastume, F., and D. G. Allen. 2005. “Activated sludge deflocculation under temperature upshifts from 30 to 45°C.” Water Res. 39 (6): 1061–1074. https://doi.org/10.1016/j.watres.2004.12.027.
Park, C., C. D. Muller, M. M. Abu-Orf, and J. T. Novak. 2006. “The effect of wastewater cations on activated sludge characteristics: Effects of aluminum and iron in floc.” Water Environ. Res. 78 (1): 31–40. https://doi.org/10.2175/106143005X84495.
Philips, S., K. Rabaey, and W. Verstraete. 2003. “Impact of iron salts on activated sludge and interaction with nitrite or nitrate.” Bioresour. Technol. 88 (3): 229–239. https://doi.org/10.1016/S0960-8524(02)00314-0.
Semblante, G. U., F. I. Hai, H. Bustamante, N. Guevara, W. E. Price, and L. D. Nghiem. 2015. “Effects of iron salt addition on biosolids reduction by oxic-settling-anoxic (OSA) process.” Int. Biodeterior. Biodegrad. 104: 391–400. https://doi.org/10.1016/j.ibiod.2015.07.005.
Van Dierdonck, J., R. Van den Broeck, E. Vervoort, P. D’haeninck, D. Springael, J. Van Impe, and I. Smets. 2012. “Does a change in reactor loading rate affect activated sludge bioflocculation?” Process Biochem. 47 (12): 2227–2233. https://doi.org/10.1016/j.procbio.2012.08.017.
Wang, Z.-P., and T. Zhang. 2010. “Characterization of soluble microbial products (SMP) under stressful conditions.” Water Res. 44 (18): 5499–5509. https://doi.org/10.1016/j.watres.2010.06.067.
Wilen, B. M., K. Keiding, and P. H. Nielsen. 2004. “Flocculation of activated sludge flocs by stimulation of the aerobic biological activity.” Water Res. 38 (18): 3909–3919.
Wilén, B.-M., and P. Balmér. 1999. “The effect of dissolved oxygen concentration on the structure, size and size distribution of activated sludge flocs.” Water Res. 33 (2): 391–400. https://doi.org/10.1016/S0043-1354(98)00208-5.
Wilén, B.-M., K. Keiding, and P. H. Nielsen. 2000a. “Anaerobic deflocculation and aerobic reflocculation of activated sludge.” Water Res. 34 (16): 3933–3942. https://doi.org/10.1016/S0043-1354(00)00274-8.
Wilén, B.-M., J. Lund Nielsen, K. Keiding, and P. H. Nielsen. 2000b. “Influence of microbial activity on the stability of activated sludge flocs.” Colloids Surf., B 18 (2): 145–156. https://doi.org/10.1016/S0927-7765(99)00138-1.
Yang, S.-f., and X.-y. Li. 2009. “Influences of extracellular polymeric substances (EPS) on the characteristics of activated sludge under non-steady-state conditions.” Process Biochem. 44 (1): 91–96. https://doi.org/10.1016/j.procbio.2008.09.010.
Zhang, L., Q. Yue, K. Yang, P. Zhao, and B. Gao. 2018. “Analysis of extracellular polymeric substances (EPS) and ciprofloxacin-degrading microbial community in the combined Fe-C micro-electrolysis-UBAF process for the elimination of high-level ciprofloxacin.” Chemosphere 193: 645–654. https://doi.org/10.1016/j.chemosphere.2017.11.056.
Zhang, P., Y. Shen, J. S. Guo, C. Li, H. Wang, Y. P. Chen, P. Yan, J. X. Yang, and F. Fang. 2015a. “Extracellular protein analysis of activated sludge and their functions in wastewater treatment plant by shotgun proteomics.” Sci. Rep. 5: 512041. https://doi.org/10.1038/srep12041.
Zhang, Y., and D. G. Allen. 2008. “The effect of short-term dissolved oxygen transients on activated sludge.” Water Qual. Res. J. Can. 43 (2–3): 201–210. https://doi.org/10.2166/wqrj.2008.023.
Zhang, Z., J. Zhang, J. Zhao, and S. Xia. 2015c. “Effect of short-time aerobic digestion on bioflocculation of extracellular polymeric substances from waste activated sludge.” Environ. Sci. Pollut. Res. 22 (3): 1812–1818. https://doi.org/10.1007/s11356-013-1887-3.
Information & Authors
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Published In
Journal of Environmental Engineering
Volume 145 • Issue 4 • April 2019
Copyright
©2019 American Society of Civil Engineers.
History
Received: Jun 13, 2018
Accepted: Sep 13, 2018
Published online: Jan 28, 2019
Published in print: Apr 1, 2019
Discussion open until: Jun 28, 2019
ASCE Technical Topics:
- Activated sludge
- Bibliographies
- Biological processes
- Design (by type)
- Dissolved oxygen
- Engineering fundamentals
- Engineering materials (by type)
- Environmental engineering
- Information management
- Load and resistance factor design
- Load factors
- Materials engineering
- Pollutants
- Polymer
- Sludge
- Structural design
- Synthetic materials
- Waste management
- Wastes
- Water quality
- Water treatment
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