Studies On Microbial Remediation Of Polluted Source Water In The Yangtze River Delta

With the rapid economic development, environmental problems of the Yangtze River Delta region have become an intractable problem, especially the pollution of source water bodies. Compared with both physical and chemical technologies, biological processes, especially the microbiological technology in source water treatment have the advantages such as low-cost, sustainability and so on. However, applications of microbial technologies for water treatment are facing lots of bottlenecks because of the region-specific hydrological environment there.The dissertation is aimed to microbial treatment of polluted water from water supply source at lab scale. The results obtained are the followings:(1) Construction of indigenous microbial floraBacterial strains of flora were isolated from different drinking water sources in the Yangtze River Delta. Three strains with high denitrification function in the condition of pH 6.5-7 were isolated and domesticated through the processes including functional domestication, UV mutagenesis and acid-resistant domestication.(2) Design and operation of the reactorsFor application of indigenous microbial flora, a laboratory system was designed and used to treat raw eutrophic source water. The system includes several removable modules and bioaugmentation technology for ensuring the formation and maintenance of the biofilm and enhancing treatment efficiency. During the operation of the system with indigenous microbial flora added, the biofilm was successfully formed, and the average removal rates of chlorophyll a, TN, and TP were 83.85%, 53.44% and 70.78%, respectively.(3) Construction and application of engineered bacteriumThe engineered strain pET-28a-napA-E.coli BL 21 MZQ-MH01 was constructed with napA recombinant plasmids transformed successfully. The embedding beads with engineered strain MZQ-MH01 were used in the system with pre-installed section for source water treatments. Components of the embedding beads were optimized before the operation. With the engineered bacterium, the concentrations of COD_Mn, TN and TP in the final effluent were low enough to be qualified (level III according to GB3838-2002) for use.