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Environmental Science and Engineering Program Seminar - Zhongwei Wang

Start Date: September 10, 2017
End Date: September 10, 2017

​​TITLE: Aerobic Granular Sludge: Effect of Salt and Insights into Microbial Ecology
DATE: Sunday, September 10, 2017
TIME: 4:00 - 5:00 p.m.
LOCATION: Auditorium 0215 · between Buildings 4 & 5​​
Aerobic granular sludge (AGS) technology is a next-generation technology for the biological treatment of wastewater. The advantages of AGS in terms of small footprint, low operation and capital cost and high effluent quality makes it a strong candidate for replacing conventional biological wastewater treatment based on activated sludge (CAS) process, and potentially become the standard for biological wastewater treatment in the future. The application of saline water (seawater or brackish) as secondary quality water for non-potable use such as toilet flushing is a promising cost-effective and environmentally friendly alternative to mitigate shortage of fresh water in some coastline cities and inland areas where brackish ground water is available. However, this practice will introduce a significant amount of inorganic salt to biological wastewater treatment plants. Salt is known to inhibit biological wastewater treatment processes in terms of organic and nutrient removal. In the first part of my dissertation, I conducted three lab-scale experiments to 1) evaluate the effect of salt on granulation and nutrient removal in AGS (330 days); 2) develop engineering strategies to mitigate the adverse effect of salt on nutrient removal of AGS (164 days); and 3) compare the effect of salt on the metabolism (stoichiometry and kinetics) of different phosphate accumulating organisms (POA) clades (PAO I and II) and to determine the effect of potassium (K+) and sodium (Na+) ions on the activities of different PAO clades (225 days).
Like other artificial microbial ecosystems (e.g. CAS plant and anaerobic digester), a firm understanding of the microbial ecology of AGS system is essential for process design and optimization. The second part of my dissertation reported the first microbial ecology study of a full-scale AGS plant with the aim of addressing the role of regional (i.e. immigration) versus local factors in shaping the microbial community assembly of different-sized microbial aggregates in AGS. The microbial communities in a full-scale AGS plant in Garmerwolde, The Netherlands, was characterized periodically over 180 days using Illumina sequencing of 16S ribosomal RNA amplicons of the V3-V4 regions. 
Overall, the discovery of this PhD study sheds light on the application of AGS for the treatment of saline wastewater and deepens our understanding on the microbial ecology of AGS systems, which is essential for process design and optimization.

Zhongwei Wang is a Ph.D. candidate at the Water Desalination and Reuse Center. He had his bachelor and master degree in environmental engineering from Beijing University of Technology in China. In 2011, he joined KAUST to pursue his Ph.D. under the supervision of Professor Pascal Saikaly. His research focused on the next-generation biological wastewater treatment technology, the aerobic granular sludge (AGS) process. He conducted three laboratory-scale experiments to evaluate the effect of salt on aerobic granulation, and the first microbial ecology study of a full-scale AGS plant.