Mechanism And Optimization Of Organic Matter Degradation By Humic-reducing Bacteria

River is an indispensable part of the urban ecosystem,and the organic matter has important influence on the environmental behavior of the pollutants.Degradable organic matter has a large number of oxygen consumption in the decomposition process.The nutrient elements such as N,P are released during the mineralization of organic matter,which is the main reason of eutrophication.Humic-reducing bacteria are widely found in sediments,which can use organic matter as electron donor,humus as electron receptor,coupling energy for cell growth.Humic-reducing bacteria can accelerate the mineralization process.Therefore,humic-reducing bacteria were used to degrade the organic matter in this project.First,the anaerobic activated sludge in the secondary sedimentation tank of domestic wastewater treatment plant was domesticated,and the domestication efficiency was measured from the reduction rate of AQDS,the increase of activated sludge concentration and the content of effective bacteria.The results showed that when the concentration of AQDS and carbon source reached 1:4,the domestication result was the best.Then,the feasibility of degradation of organic matter by humic reducing bacteria was studied.The activated sludge and humic-reducing bacteria which was enriched by the former group both shew degradation effect on organic matter.Second,the degradation mechanism of humic-reducing bacteria was discussed from the aspects of the humification coefficient of sediment,Ca?NO₃?₂ and biogenerating agent dosage.The results showed that the amount of organic matter degradation decreased with the increase of humification coefficient,and increased with the improving of Ca?NO₃?₂ and biogenerating agent dosage.The addition of Ca?NO₃?₂ significantly improved the redox state of sediment and introduced NO₃^-as electron acceptor,which promoted degradation of organic matter through aerobic process.When the dosage of Ca?NO₃?₂ reached 0.20 g/kg,the sediment ORP increased by 177 mV.After remediation,the degradation amount of total organic matter,heavy form organic matter and light form organic matter were 2.71,2.06,0.65g/kg.The addition of biogenerating agent can provide anaerobic environment for humic-reducing bacteria and promote degradation of organic matter through anaerobic process.When the dosage of biogenerating agent reached 0.024 g/kg,the sediment ORP decreased by 183 mV in 7 days.After remediation,the degradation amount of total organic matter,heavy form organic matter and light form organic matter were13.21,6.57,6.64 g/kg.Finally,biochemical remediation were used to optimize the degradation conditions of organic matter in sediment.The results showed that the optimum amount of activated sludge was 1 mL/L,the dosage of Ca?NO₃?₂ and biogenerating agent were 0.20 and 0.024 g/kg respectively.After remediation,the degradation amount of total organic matter,heavy form organic matter and light form organic matter were 13.80,6.31,7.49 g/kg.