Role And Mechanism Study On Microbe In Treatment Of Scenic Water By Biological Grid

As the high-speed development of economy and society, most scenic water isseriously polluted and the capability of self-purification is decreased in recent years.Therefore, it is particularly important to solving the eutrophication and restoring theecological function of landscape water. The ecological restoration technology ofscenic water has become a hot topic at domestic research.In order to study the purification effects, a pilot biological grid device was builtand different plant biological grid system were set to compare the difference ofpurification effects on eutrophic landscape water. In order to study the role andmechanism of microorganism on contaminant removal in biological grid systems,four small pilot devices, which were respectively filling group, Irispseudoacorusfloating-beds, Irispseudoacorus biological grid, Cannaindica biological grid, wereconstructed during the dynamic experiments. The dynamic characteristics of eachsmall pilot’s treatment efficiency on landscape water, the number of bacteria and fungi,and the activity of dehydrogenase were continuously monitored. At the beginning andend stage of the four pilot devices the roots of plant and fibrous fillers were selected.The molecular biological method of PCR-DGGE was applied to analyze the microbialcommunity structure and diversity of those samples and some bands of the dominantspecies were recycled and sequenced. The sequencing results were imported into theBLAST and the phylogenetic tree was constructed.Comparing the purification effects of different plant biological grid system onlandscape water, the results indicate that Cannaindica biological grid has a higherremoval rate. The dynamic operation conditions of the four small pilot devices arethat HRT is4days and influent flow is8.6L/d, which continue more than3months.The results show that the purification effects become better and more stable with theincreasing of running time. The average removal efficiency of CODCr, TN, NH4+-N,TP for the fibre filling small pilot device are respectively23.1%,15.3%,18.1%and19.4%lower than Irispseudoacorus biological grid, the number of which increase by14.2%,12.8%,7.9%and11.9%compared with Irispseudoacorus ecological floatingbed. The average removal rate of Cannaindica biological grid for CODCr, TN,NH4+-N, TP are60.8%,43.8%,49.6%and37.8%respectively. The average effluentconcentrations of CODCr, NH4+-N, TP in Irispseudoacorus and Cannaindicabiological grid small pilot plant attained the Class Ⅳ of water quality standards (GB 3838-2002). Contrasting the change of bacteria and fungi’s number on the plant rootand fibre filling of the four pilot devices, it imply that the bacteria mainly attache onthe fiber filling and the fungi are mostly distributed at the roots of plant. The activityof dehydrogenase could characterize activity of microbial, after comparison the resultsshowe that the activity of fibrous filler gathering most microorganisms is much higherthan that of plant root.The Shannon index of samples selected at the start and ending of the experimentis from0.85to1.05, which demonstrates that the microbial population is veryabundant. The microbial community structures of the filling between the filling groupand biological grid system have a lower similarity. The sequencing results show thatthe fibre filling collecte most non-cultured bacteria species and the majority ofbacteria on the plant roots are β-Proteobacteria and α-Proteobacteria. Theco-dominant species attaching on the filling and plant is Nitrosomonadaceae.