Analysis of biofilm microbial community structure dynamics by ERIC-PCR fingerprinting for eutrophication water purification

The relation between dynamic change in microbial community structure and major pollutant remove effect was analyzed by ERIC-PCR fingerprinting combined with routine technique. A new technique, with medium biofilms and hydrophytes as main components, and microbes, plankton, hydrophytes and aquatic animals as basic ecological elements, was used to deal with an eutrophication river in Shanghai. A pilot-scale test was carried out, combining seven reaction ponds parallel, with continuous influent and effluent. As the device had obvious effect on eutrophication water pollution removal, the removal efficiencies of COD_Cr, TN, NH₄-N and TP were 13.35%-58.6%, 23.6%-65.8%, 15.5%-72.9% and 16.8%-76.9% higher than those of control group. The medium biofilm microbial population diversity indexes increased during the experiments, with the first collected sample ranging from 1.77 to 1.91 and the second from 1.96 to 2.35 in experiment one. The three ponds planted with Eichhornia crassipes had more abundant microbial species than those without hydrophytes, according to the results of ERIC-PCR bands. In experiment two, ponds 3, 5 and 7 with 7.5 h HRT had more abundant ERIC-PCR fingerprinting bands than ponds 2, 4 and 6 ponds with 4 h HRT. The HRT had less influence on root biofilm microbial community structure. In conclusion, as the experiments progressed, the population diversity index increased and the system gradually became stable.