Research Of Biostimulants In Stimulating Microbial Activities Of Constructed Wetland Systems

In order to solve the problem of low microbial activity in the operation process of constructed wetland,biostimulants?BS?was supplied to constructed wetland systems to stimulate its microbial activities to improve the effects of water purification.Vertical flow constructed wetland system was used as the research object in this study.In order to provide a theoretical basis for the practical application of biostimulants,this study discussed the effects of the different supplement of biostimulants on effluent quality and substrate enzymatic activities of constructed wetland systems and got a optimum supplement of biostimulants.On the basis of this,the effects of biostimulants on water purification performance and microbial activities of constructed wetland systems were study.The specific research contents and results are as follows:?1?In this study,the biostimulants were applied to the water purification process of constructed wetlands,0?L/L,1?L/L,5?L/L and 10?L/L biostimulants was supplied to the influent of constructed wetlands.The optimum supplement of biostimulants was obtained by analysising effluent quality and substrate enzymatic activities of constructed wetland systems.The results showed that:?1?The system supplied with 5?L/L biostimulants got the best water purification performance,the removal efficiencies of TN and NH₄⁺-N reached up to 80%and increased by 71.5%and 31.7%compared with the control systems,the removal efficiencies of TP and COD reached36.0%and 91.6%and increased by 9.1%and 5.9%compared with the control systems;?2?The supplement of biostimulants could improve the activities of substrate phosphatase and urease in the constructed wetland systems,there was no significant difference between the different systems for substrate phosphatase activities and the supplement of 5?L/L biostimulants had a significant effect on the substrate urease activities?P<0.05?;?3?There was a significant positive correlation between the average COD removal efficiency and the activities of substrate phosphatase and urease in the constructed wetland systems?P<0.05?.?2?With the optimum supplement of biostimulants,the mechanism of biostimulants stimulating the microbial activities of constructed wetland systems was studied.Effluent quality was determined to analyse the effects of wetland plants and biostimulants on the water purification performance of constructed wetland systems.And mechanism was analyzed by determining the substrate enzymatic activities and the differences of microbial community structures of the different systems.The results showed that:?1?The supplement of biostimulants could significantly improve the removal of NH₄⁺-N and TP?P<0.05?,the removal efficiencies of NH₄⁺-N and TP in the systems supplied with biostimulants reached 44.6%and 53.6%and increased by16.4%and 10.4%compared to the systems without supplying biostimulants;?2?The colonization of wetland plants could significantly improve the removal of TP and COD?P<0.05?,the removal efficiencies of TP and COD in the systems colonized with plants reached 43.2%and 93.0%and increased by 16.5%and 7.3%compared to the systems without plants;?3?The colonization of wetland plants could significantly improve the substrate phosphatase activities?P<0.05?,and the combined interaction of colonization of wetland plants and supplement of biostimulants could significantly improve the substrate urease activities in the systems?P<0.05?;?4?There was a significant positive correlation between the substrate phosphatase activities and average TP removal efficiency?P<0.05?,as well as between the substrate phosphatase activities and average COD removal efficiency?P<0.01?,and between the substrate urease activities and average COD removal efficiency?P<0.01?;?5?Biostimulants could improve relative abundance of common phylum of bacteria,but there was no significant difference betweem the different systems.Biostimulants could significantly improve the relative abundance of genus of bacteria?P<0.05?,such as Thermonomonas and Cloacibacterium.