Gas-enhanced operation and stepwise organic stressing as a new alternative in realising successful sludge granulation in high-rate anaerobic bioreactor for wastewater treatment

To Hung TsuiDepartment of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Hong Kong Branch of Chinese National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of ChinaView further author information

Tianwei HaoDepartment of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Hong Kong Branch of Chinese National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of ChinaCorrespondence[email protected]
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Guang Hao ChenDepartment of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Hong Kong Branch of Chinese National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China;Wastewater Treatment Laboratory, Fok Ying Tung Graduate School, The Hong Kong University of Science and Technology, Nansha, Guangzhou, People's Republic of ChinaView further author information

ABSTRACT

Anaerobic biotechnology is becoming the method of choice for many types of wastewater treatment. Application of granular sludge in the upflow anaerobic sludge bed (UASB) is important in maximising the overall treatment capacity benefiting from its fast settling ability and excellent biological activities. This study explores a new alternative for achieving sludge granulation in a sulfidogenic UASB reactor. Granules were first observed at day 30 and achieved the average diameters of 820 µm at day 162. The scanning electron microscope analysis showed that the granules have a regular spherical-shaped outline boundary, and a rough outer surface layer with a channel-like porous structure. The confocal laser scanning microscopy analysis illustrated that the extracellular polymeric substances (EPS) were more evenly distributed across the granules under a gas-enhanced operation than at the control stage. For the control stage operation without gas-enhanced operation, no granule disintegration was observed and accumulation of two hydrophobic EPS (protein and lipid) on the granule’s outer layer surface was revealed. The pyrosequencing analysis of the 16s rRNA gene found that the microbial community contained more diverse sulfate reducing bacteria genera (15 genera), and the ratio of acidogens to sulfate reducing bacteria was much higher than previous study.

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To Hung Tsui

Mr To Hung Tsui received his BEng degree in Civil and Environmental Engineering from The Hong Kong University of Science and Technology (HKUST) in 2013. He is currently a Ph.D. candidate supervised by Prof Guang Hao Chen at the HKUST. His research interests include developing efficient wastewater treatment methods and ways to recover resources such as heavy metals from waste streams.

Tianwei Hao

Dr Tianwei Hao is currently a postdoctoral research fellow in the HKUST working on design and operation of sulfate reduction, autotrophic denitrification, nitrification integrated (SANI®) process demonstration plant. He obtained his Ph.D. degree in Civil Engineering from the HKUST in 2014. His research interests include biological saline sewage treatment, biological sulfur conversion and granular sludge.

Guang Hao Chen

Prof Guang Hao Chen is a Professor at the HKUST and an Associate Editor of Water Research. He was an elected Fellow of the International Water Association (IWA) in 2011 and a distinguished Fellow of IWA in 2016. He has completed over 40 research projects in the field of wastewater treatment, covering pilot- and full-scale studies. His researches on the triple water supply (TWS) system, the SANI® process, and the seawater-based urine phosphorus recovery (SUPR®) process have won five international awards in 2012, including the International Huber Technology Prize of Germany, the Smart Cities (Project Category) Finalist Award of Barcelona in Spain, the IWA Sustainability Specialist Group Prize, and the East Asia Honour Award and Global Honour Award of the IWA Project Innovation Award in Applied Research.

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