| Heavy metal wastewater is a major source of environmental pollution at this stage.Currently,there are a number of methods to treat heavy metals in water,but most of them focus on physical removal and chemical removal.These methods generally have some drawbacks including low efficiency,high treatment cost,complex treatment process and secondary pollution.Sulfate-reducing bacteria?SRB?which is a facultative anaerobes exists widely in nature.It can generate H2S through consuming organic acid metabolism under anaerobic conditions.The researches find that the heavy metal wastewater can be treated using the feature of SRB.The present study isolated three strains of SRB from different sampling locations.Settling efficiency of three strains for 10 mg/L Cu2+and Ni2+reached to 98%and 75%,respectively.The settling efficiencies for Fe2+,Cd2+and Zn2+were particularly high,and they could reached to100%for 15 mg/L Fe2+,and 20mg/L Cd2+and Zn2+.Precipitation of heavy metal obtained by SRB was analyzed by XRD.Result indicated that the main component of the precipitation was metal sulfide.In the study of effects of SRB on plant growth,the shoot length,root length,and entire growth of corn seedling treated with SRB had obvious advantages compared with the control groups.When the corn seedlings were digested,the amount of heavy metal in SRB treated group was less than 50%compared with the untreated group.In addition,both direct and indirect processing models for treatment of Cu,Fe,Ni,Cd,Zn mixed waste were desighed according to the growth characteristics of the SRB.The results showed that when the volume of mixed bacteria and 500 mg/L heavy metal mixed wastewater was 1:5,the treatment effeciency of SRB using directly model was more than 50%.When 500 mg/L heavy metal mixed wastewater was treated with the mixed bacteria by a ventilation 4 h a day,the treatment effeciency of SRB using indirect processing models was more than 50%after 5 days. |
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