Study On The Applied Technology Of Nitrogen Control In Dredged Eutrophic Water By Microbes

Sediment dredging is the most common method of eutrophic lake restoration, but it will cause a series of environmental problems at the same time. In this paper, the method combining sediment dredging with microbial remediation was studied, which could make up for the inadequacy of sediment dredging. The main results were as follows:(1) Screening of denitrifying bacteriaA strain ADH1(Pseudomonas stutzeri) that had best denitrification character in denitrification medium and LB medium containing nitrate was screened. The nitrate and total nitrogen removal efficiency were 100% and 82% respectively.(2) The effects of different nitrogen cycling bacteria in tub modelAmmonifying bacteria could significantly enhance the sediment to release ammonia, and make the ammonia in overlying water increased from 0.244 mg/L to 0.908 mg/L.Nitrifying bacteria could significantly improve the removal efficiency of ammonia in overlying water, low ammonia and high ammonia water model, the removal efficiency of ammonia were 83.9% and 99.5% respectively after supplemented with nitrifying bacteria. Both denitrifying bacteria ADH1 and DNF can improve the removal efficiency of nitrate nitrogen and total nitrogen. The removal efficiency of nitrate nitrogen and total nitrogen of DNF were 99.5% and 89.2%, and the removal efficiency of nitrate nitrogen and total nitrogen of ADH1 were 82.5% and 54.4%(3) The impact on the nutrient release of dredging and microbial remediation indifferent pollution simulation systemDredging could effectively inhibit the release of ammonia in sediment when the sludge layer was thin. Both dredging and microbial remediation could effectively reduce the nutrient concentration in heavily-polluted overlying water, and when the pollutants concentration was low, both dredging and microbial remediation would break the equilibrium in overlying water and sediment, result in ammonia releasing from sediment in the short time; Supplemented with nitrogen cycle related microorganisms could stimulate release of ammonia from sediment, the ammonia concentration of microorganisms supplemented groups were higher as much as 3.02 mg/L than control groups, at the end of the experiment, the total nitrogen in sediment was about 19% lower than control groups. Dredging could affect the denitrification of lake system, lead to nitrification increased and denitrification weakened. Supplemented denitrifying bacteria after sediment dredging could strengthen the denitrification of lake system and accelerate the removal of nitrate and total nitrogen, the concentration of nitrate and total nitrogen in overlying water in microorganisms supplemented groups were higher as much as 3.1 mg/L and 2.3 mg/L than control groups.(4) The impact on the nutrient release of dredging and microbial remediation indifferent pollution simulation system while with external pollutionWhen external pollution was added into the simulation system, a large consumption of dissolved oxygen would inhibit nitrification and block nitrogen cycle then lead to pollutant accumulation; when dissolved oxygen was enough, microorganisms and dredging could both promote nitrification; supplemented with nitrogen cycle related microorganisms could stimulate the release of ammonia, the release quantity increase 0.03 mg/L ~2 mg/L. When there was external pollution,supplemented denitrifying bacteria had no obvious effect on remove of nitrate and total nitrogen. Dredging can promote the sediment adsorption of total nitrogen.