Comparison between Conventional Bacterial and Algal-Bacterial Aerobic Granular Sludge Systems in the Treatment of Saline Wastewater

Authors: Philip Semaha, Zhongfang Lei, Ziwen Zhao, Sen Liu, Zhenya Zhang, Kazuya Shimizu

Abstract:

The increasing generation of saline wastewater through various industrial activities is becoming a global concern for activated sludge (AS) based biological treatment which is widely applied in wastewater treatment plants (WWTPs). As for the AS process, an increase in wastewater salinity has negative impact on its overall performance. The advent of conventional aerobic granular sludge (AGS) or bacterial AGS biotechnology has gained much attention because of its superior performance. The development of algal-bacterial AGS could enhance better nutrients removal, potentially reduce aeration cost through symbiotic algae-bacterial activity, and thus, can also reduce overall treatment cost. Nonetheless, the potential of salt stress to decrease biomass growth, microbial activity and nutrient removal exist. Up to the present, little information is available on saline wastewater treatment by algal-bacterial AGS. To the authors’ best knowledge, a comparison of the two AGS systems has not been done to evaluate nutrients removal capacity in the context of salinity increase. This study sought to figure out the impact of salinity on the algal-bacterial AGS system in comparison to bacterial AGS one, contributing to the application of AGS technology in the real world of saline wastewater treatment. In this study, the salt concentrations tested were 0 g/L, 1 g/L, 5 g/L, 10 g/L and 15 g/L of NaCl with 24-hr artificial illuminance of approximately 97.2 µmol m¯²s¯¹, and mature bacterial and algal-bacterial AGS were used for the operation of two identical sequencing batch reactors (SBRs) with a working volume of 0.9 L each, respectively. The results showed that salinity increase caused no apparent change in the color of bacterial AGS; while for algal-bacterial AGS, its color was progressively changed from green to dark green. A consequent increase in granule diameter and fluffiness was observed in the bacterial AGS reactor with the increase of salinity in comparison to a decrease in algal-bacterial AGS diameter. However, nitrite accumulation peaked from 1.0 mg/L and 0.4 mg/L at 1 g/L NaCl in the bacterial and algal-bacterial AGS systems, respectively to 9.8 mg/L in both systems when NaCl concentration varied from 5 g/L to 15 g/L. Almost no ammonia nitrogen was detected in the effluent except at 10 g/L NaCl concentration, where it averaged 4.2 mg/L and 2.4 mg/L, respectively, in the bacterial and algal-bacterial AGS systems. Nutrients removal in the algal-bacterial system was relatively higher than the bacterial AGS in terms of nitrogen and phosphorus removals. Nonetheless, the nutrient removal rate was almost 50% or lower. Results show that algal-bacterial AGS is more adaptable to salinity increase and could be more suitable for saline wastewater treatment. Optimization of operation conditions for algal-bacterial AGS system would be important to ensure its stably high efficiency in practice.

Keywords: Algal-bacterial aerobic granular sludge, bacterial aerobic granular sludge, nutrients removal, saline wastewater, sequencing batch reactor.

References:

[1] Moussa, M.S., D.U. Sumanasekera, S.H. Ibrahim, H.J. Lubberding, C.M. Hooijmans, H.J. Gijzen, and M.C.M. Van Loosdrecht. "Long term effects of salt on activity, population structure and floc characteristics in enriched bacterial cultures of nitrifiers." Water Research 40, no. 7 (2006), 1377-1388.
[2] Moon, B.-H., G.-T. Seo, T.-S. Lee, S.-S. Kim, and C.-H. Yoon. "Effects of salt concentration on floc characteristics and pollutants removal efficiencies in treatment of seafood wastewater by SBR." Water Science and Technology 47, no. 1 (2003), 65-70.
[3] Lefebvre, Olivier, and René Moletta. "Treatment of organic pollution in industrial saline wastewater: A literature review." Water Research 40, no. 20 (2006), 3671-3682.
[4] Wu, G., Y. Guan, and X. Zhan. "Effect of salinity on the activity, settling and microbial community of activated sludge in sequencing batch reactors treating synthetic saline wastewater." Water Science and Technology 58, no. 2 (2008), 351-358.
[5] Mishima, K., and M. Nakamura. "Self-Immobilization of Aerobic Activated Sludge–A pilot study of the aerobic upflow sludge blanket process in municipal sewage treatment." Water Science and Technology 23, no. 4-6 (1991), 981-990.
[6] Wang, Xingang, Tongyi Yang, Bing Lin, and Yubin Tang. "Effects of salinity on the performance, microbial community, and functional proteins in an aerobic granular sludge system." Chemosphere 184 (2017), 1241-1249.
[7] Adav, Sunil S., and Duu-Jong Lee. "Extraction of extracellular polymeric substances from aerobic granule with compact interior structure." Journal of Hazardous Materials 154, no. 1-3 (2008), 1120-1126.
[8] Adav, Sunil S., Duu-Jong Lee, and Joo-Hwa Tay. "Extracellular polymeric substances and structural stability of aerobic granule." Water Research 42, no. 6-7 (2008), 1644-1650.
[9] De Kreuk, M.K., J.J. Heijnen, and M.C.M. Van Loosdrecht. "Simultaneous COD, nitrogen, and phosphate removal by aerobic granular sludge." Biotechnology and Bioengineering 90, no. 6 (2005), 761-769.
[10] Adav, Sunil S., Duu-Jong Lee, Kuan-Yeow Show, and Joo-Hwa Tay. "Aerobic granular sludge: Recent advances." Biotechnology Advances 26, no. 5 (2008), 411-423.
[11] Corsino, Santo F., Riccardo Campo, Gaetano Di Bella, Michele Torregrossa, and Gaspare Viviani. "Cultivation of granular sludge with hypersaline oily wastewater." International Biodeterioration & Biodegradation 105 (2015), 192-202.
[12] Corsino, Santo F., Marco Capodici, Claudia Morici, Michele Torregrossa, and Gaspare Viviani. "Simultaneous nitritation–denitritation for the treatment of high-strength nitrogen in hypersaline wastewater by aerobic granular sludge." Water Research 88 (2016), 329-336.
[13] Figueroa, M., A. Mosquera-Corral, J. L. Campos, and R. Méndez. "Treatment of saline wastewater in SBR aerobic granular reactors." Water Science and Technology 58, no. 2 (2008), 479-485.
[14] Tchobanoglous, George, Franklin L. Burton, H. D. Stensel, Inc. Metcalf & Eddy, and Franklin Burton. "Chapter 4." In Wastewater Engineering: Treatment and Reuse, 4th ed., 217. London: Palgrave Macmillan, 2003.
[15] Rosso, Diego, Lory E. Larson, and Michael K. Stenstrom. "Aeration of large-scale municipal wastewater treatment plants: state of the art." Water Science and Technology 57, no. 7 (2008), 973-978.
[16] Ahmad, Johan S., Wei Cai, Ziwen Zhao, Zhenya Zhang, Kazuya Shimizu, Zhongfang Lei, and Duu-Jong Lee. "Stability of algal-bacterial granules in continuous-flow reactors to treat varying strength domestic wastewater." Bioresource Technology 244 (2017), 225-233.
[17] Bungay, Mary L., and Henry R. Bungay. "Fundamental Concepts for Environmental Processes." Biological Treatment Processes, 8th ed., Humana P, NJ, 2009.
[18] Muñoz, Raul, and Benoit Guieysse. "Algal–bacterial processes for the treatment of hazardous contaminants: A review." Water Research 40, no. 15 (2006), 2799-2815.
[19] Ji, Xiyan, Mengqi Jiang, Jibiao Zhang, Xuyao Jiang, and Zheng Zheng. "The interactions of algae-bacteria symbiotic system and its effects on nutrients removal from synthetic wastewater." Bioresource Technology 247 (2018), 44-50.
[20] Zhang, Bing, Piet N. Lens, Wenxin Shi, Ruijun Zhang, Zhiqiang Zhang, Yuan Guo, Xian Bao, and Fuyi Cui. "Enhancement of aerobic granulation and nutrient removal by an algal–bacterial consortium in a lab-scale photobioreactor." Chemical Engineering Journal 334 (2018), 2373-2382.
[21] Zhao, Ziwen, Xiaojing Yang, Wei Cai, Zhongfang Lei, Kazuya Shimizu, Zhenya Zhang, Motoo Utsumi, and Duu-Jong Lee. "Response of algal-bacterial granular system to low carbon wastewater: Focus on granular stability, nutrients removal and accumulation." Bioresource Technology 268 (2018), 221-229.
[22] Wang, Zhongwei, Mark C. Van Loosdrecht, and Pascal E. Saikaly. "Gradual adaptation to salt and dissolved oxygen: Strategies to minimize adverse effect of salinity on aerobic granular sludge." Water Research 124 (2017), 702-712.
[23] Campo, Riccardo, Santo F. Corsino, Michele Torregrossa, and Gaetano Di Bella. "The role of extracellular polymeric substances on aerobic granulation with stepwise increase of salinity." Separation and Purification Technology 195 (2018), 12-20.
[24] Huang, Wenli, Bing Li, Chao Zhang, Zhenya Zhang, Zhongfang Lei, Baowang Lu, and Beibei Zhou. "Effect of algae growth on aerobic granulation and nutrients removal from synthetic wastewater by using sequencing batch reactors." Bioresource Technology 179 (2015), 187-192.
[25] American Public Health Association. Standard Methods for the Examination of Water and Wastewater. American Public Health Association, Washington, DC, USA, 2012.
[26] Li, Z. H., and X. C. Wang. "Effects of salinity on the morphological characteristics of aerobic granules." Water Science and Technology 58, no. 12 (2008), 2421-2426.
[27] Li, Xiling, Jinghai Luo, Gang Guo, Hamish R. Mackey, Tianwei Hao, and Guanghao Chen. "Seawater-based wastewater accelerates development of aerobic granular sludge: A laboratory proof-of-concept." Water Research 115 (2017), 210-219.
[28] Lee, Duu-Jong, Yu-You Chen, Kuan-Yeow Show, Chris G. Whiteley, and Joo-Hwa Tay. "Advances in aerobic granule formation and granule stability in the course of storage and reactor operation." Biotechnology Advances 28, no. 6 (2010), 919-934.
[29] Tay, J.-H., Q.-S. Liu, and Y. Liu. "Microscopic observation of aerobic granulation in sequential aerobic sludge blanket reactor." Journal of Applied Microbiology 91, no. 1 (2001), 168-175.
[30] De Sousa Rollemberg, Silvio L., Antônio R. Mendes Barros, Paulo I. Milen Firmino, and André Bezerra dos Santos. "Aerobic granular sludge: Cultivation parameters and removal mechanisms." Bioresource Technology 270 (2018), 678-688.
[31] Cui, You-Wei, Hong-Yu Zhang, Jie-Ran Ding, and Yong-Zhen Peng. "The effects of salinity on nitrification using halophilic nitrifiers in a Sequencing Batch Reactor treating hypersaline wastewater." Scientific Reports 6, no. 1 (2016).
[32] Pronk, M., J. P. Bassin, M. K. De Kreuk, R. Kleerebezem, and M. C. Van Loosdrecht. "Evaluating the main and side effects of high salinity on aerobic granular sludge." Applied Microbiology and Biotechnology 98, no. 3 (2013), 1339-1348.