Experimental Study On Purification Of Pathogenic Microorganisms In Landscape Water By Immobilized Bdellovibrio

In the process of developing Sponge City by collecting rainwater and reclaimed water,the pathogenic microorganisms in rainwater and reclaimed water will threaten urban landscaping water environment.Immobilized Bdellovibrio by ceramization of sludge particles to purify pathogenic microorganisms in urban landscaping water can avoid detrimental impact on aquatic ecosystems due to physical and chemical treatment approaches.The study and its findings are described below.(1)Field investigations are conducted on the growth and decay of pathogenic microorganisms in the Yanling Wetland in Dongguan which is supplemented by rainwater and urban reclaimed water.The results show that the amount of pathogenic microorganisms represented by the index pathogenic microorganisms in the water body increases gradually from upstream to downstream.The rate of proliferation is related to water quality while the sedimentation is affected by the velocity of water flow.(2)A double-deck agar plate culture method is used to isolate Bdellovibrio that could lyse the pathogenic microorganisms such as total coliforms and fecal coliforms from water in Yanling Wetland in Dongguan.(3)Collection of sludge samples from Yanling Wetland to prepare ceramization of sludge particles for immobilizing Bdellovibrio.The results show that the best fixing condition of Bdellovibrio is to set the ceramization temperature at 800 °C,adsorption time at 6h,the culture temperature at 30 °C,the shaker speed at 140 r/min.Under this condition,the removal rate of E.coli reaches 97.4%,which is far more than that of the control group during the 72 h test period.(4)By using sulfuric acid modified carrier,the effects of sulfuric acid concentration,modification time,modification temperature and other factors on the immobilization of Bdellovibrio by ceramization of sludge particles were investigated.The results of modification show that the optimum conditions for the modification of ceramization of sludge particles is sulfuric acid of 4 mol/L,modification time of 4 h and modification temperature of 60 °C.After modification,the specific surface area of the ceramic slurry increases by 11% and the surface hydroxyl functional groups increase as well.The results of comparative studies show that the modified ceramization sludge particles fix the total coliform and fecal coliform of the Yanling Wetland in Dongguan with the removal rates of 97.5% and 78%,respectively.The removal effect is far better than the control group.Based on the results of the study,the following conclusions can be reached.The method of immobilizing Bdellovibrio with ceramization sludge particles and biological purification of pathogenic microorganisms according to local conditions are capable to treat water based on features of specific landscaping water environment.It can provide new guidance to improve urban landscaping water environment.