Comparative Research For Sterilization Methods To Pathogenic Bacteria From Lakes-desilting Sludge

With the current social and economic development in our country,the problem of environmental pollution has been increasingly serious,and the urban lake’s pollution problem is especially outstanding.Lake dredging is one of the most effective means for lake pollution management.Hubei province is famous as "province of thousands of lakes",each year,great amount of dredging sediment generated,and the comprehensive utilization for dredging sediment has been a big problem.Hubei province,at the same time,is a province which is rich in mineral resources,and the ecological environment was destroyed with the mineral exploration.While the key problem that restricts the reconstruction of local ecological environment is the soil source for reclamation.So if the dredging sediment can be used as the soil source for reclamation,the purpose of promoting the efficiency of comprehensive utilization of dredging sediment and ’turning waste into wealth’ would come true,and the bottle neck problem of soil source for reclamation will be solved at the same time.However,because of the pollution and the abundant bacteria,it needs to be conduct with sterilization process before the utilization.The research object of this paper is lake dredging sediment,of which the sample was sampling from Daye lake.In this paper,we carried on examination for total bacteria,total coliform group and bacteria species,and analyze the necessity for sterilization for lake dredging.Then,we chose H2O2,NaCIO and ultraviolet ray which are three kinds of common sterilization methods,taking coli as experimental subject,to explore its’ efficiency for sterilization and its’ best condition parameters.On this basis,we continue conducting sterilization confirmatory experiment for lake dredging,taking different lakes’ dredging as the experimental subject,to checking the applicability and effectiveness of the above sterilization methods.The main research results are as fallow:From the examination results of the dredging of Daye lake,according to the reuse standard of dredging about value of the coliform group,which is being greater than 0.01,quoted from ’The best feasible technical guidelines of pollution prevention and control for dredging treatment and disposal from urban sewage treatment plant(trial 2010)HJ-BAT-002’,4 of the 8 samples from Daye lake,that are NO.1,4,5,7,do not satisfy the provision,its’amount of total bacteria in 1 gram dredging are 3.8×106,7.0×106,3.2×106,6.9×106,respectively,and its’ amount of total coliform group in 1 gram dredging are 1.2×102,1.9×105,1.1×105,1.7×105,and its’ corresponding value of the coliform group are 0.008,0.009,0.005,0.006.In addition,pathogenic bacteria like helicobacter was found in the results of bacteria species examination.Therefore,before being used as soil matrix for mine reclamation,dredging from Daye lake need sterilization processing.When taking e.coli as the research subject,all of the sterilization methods of H2O2,NaClO and ultraviolet ray have good sterilization efficiency,Of which,program of sterilization by H2O2 with 1%volume fraction can kill all the bacteria in 5 min,program of sterilization by NaClO with mass concentration of 0.8mg/L can reach sterilization efficiency of 100%in 0.5 min,and,at a definite radiate level,ultraviolet ray can kill more than 98%bacteria in 30 seconds.When taking dredging from Longyang lake,Moshui lake,sand lake,east lake and Daye lake as the sterilization subject,taking total number of coli group for the reference standard,in 10 min,sterilization efficiency of the above five lakes by H2O2 with 1%volume fraction are 15.6%、38.5%、59.7%、46.7%and 53.3%,respectly;that for UV exposure for 30 seconds are 12.5%、21.0%、48.1%、40%and 17.8%,in relevant;and that for NaClO with mass concentration of 0.8mg/L are 13.9%、11.5%、20.8%、6.7%and 22.2%.Therefore,sterilization efficiency of H2O2 is the relevantly best in the three kinds of sterilization methods,and has certain practical application value,and the sterilization efficiency of ultraviolet ray and NaClO are not stable,thus declining drastically,which may be concerned with the properties of dredging,and need further study.This research provides technology supports for comprehensive utilization of lake dredging,and has great realistic significance for lake pollution management and ecological construction in mine areas.