Removal Of AVS Pollution From River Sediments By Immobilized Sulfur Oxidizing Bacteria In Water Purification Sludge

At this stage,the small and medium-sized rivers in many cities and towns in China have appeared the phenomenon of black and smelly water in varying degrees,which not only led to the destruction of the ecological environment along the river,but also directly affected the quality of life of the surrounding residents.In the natural water environment,H₂S in the sediment is released into the interstitial water in the bottom mud and the overlying water body,which will combine with ions such as iron and manganese to blacken the water body.The release of H₂S from rivers and lakes to the air will also make the water body stink.Therefore,the removal of acid volatile sulfide（AVS）pollution in the river is very important for the treatment of black and smelly water body.In this thesis,the immobilized microbial technology is used to remove the AVS pollution in the river.Using the purified water sludge,the waste product of the waterworks,the immobilized carrier is prepared by burning at high temperature,which can achieve a good effect of"treating pollution with waste".Then the commercially available sulfur oxidizing bacteria were immobilized,and the remediation effect of immobilized sulfur oxidizing bacteria on black and smelly water was verified through a series of comparative tests,response analysis,high-throughput sequencing and field tests,it provides a new solution for the treatment of black and smelly water in the future.The main achievements of this thesis are as follows:The immobilized carrier of water purification sludge was prepared by high-temperature burning.It was concluded that the optimal temperature of the carrier under the calcination time of 2H was 600℃.Generally,the adsorption effect of small particle size on sulfide is good,but the dosage should not be too large.At the same concentration,the adsorption capacity of sulfide by water purification sludge is significantly better than that of green zeolite and activated carbon.The adsorption process of sulfide by water purification sludge carrier is physicochemical adsorption,this fits better with the quasi second-order kinetic model.The sludge column test under laboratory conditions found that the removal rate of water purification sludge carrier calcined at high temperature reached 15%,which was significantly better than that of green zeolite and activated carbon.Compared with the direct addition of bacterial agent,no matter what carrier is used,the AVS removal rate of immobilized sulfur oxidizing bacteria is better,and the AVS removal rate of water purification sludge group is the best,reaching 86%.The immobilization conditions were optimized by single factor test.When the temperature was 30℃,p H=6 and the immobilization time was 24h,the biomass of sulfur oxidizing bacteria was the largest and the removal rate of AVS was better.After optimization by response surface method,the optimum conditions were obtained:temperature 30.36℃,p H5.71 and immobilization time 25.76h.The order of influence on the immobilization effect is temperature<p H<immobilization time.In the outdoor test of dawula Village section of Xihe River,AVS in the sediment has been well removed,but the removal effect is not as good as that in the laboratory because the natural water conditions are more complex than that in the laboratory.After 56 days of repair,AVS decreased from 226mg/kg at the beginning of the test to 34.4mg/kg,and the removal rate reached 84.9%.Within 42d,the g value changes from 0.51×10-3kg/（kg·h）increased to 1.56×10-3kg/（kg·h）,with the highest growth rate of 205%,which indicates that the addition of immobilized sulfur oxidizing bacteria optimizes the biodegradability of sediment.The differences of microbial community structure in The microbial population of sediment before and after the addition of immobilized microorganisms was characterized by high-throughput sequencing technology.The results showed that the richness and diversity of bacterial community would be higher after the addition of immobilized sulfur oxidizing bacteria,and some specific strains could be clustered.It can be seen from the research at the phylum level that the addition of immobilized microorganisms improves the average abundance of Proteus,and the maximum abundance can reach 51.28%,and effectively inhibits the growth and reproduction of desulfurization bacteria.The genus level study found that the relative abundance of Thiobacillus was the highest after adding water purification sludge immobilized Thiobacillus,reaching 12.09%,and the addition of immobilized microorganisms had a certain effect on inhibiting the growth and reproduction of sulfate reducing bacteria such as Vibrio thermodesulfuricus,and played a certain role in improving the black and odor environment in the sediment.The research shows that the effect of water purification sludge immobilized sulfur oxidizing bacteria in removing AVS pollution in black and smelly river is very significant.Using water purification sludge as raw material to prepare microbial immobilized carrier has certain innovation and feasibility,and has certain economic benefits and broad development prospects in the in-situ repair and treatment project of black and smelly river.