Research On Geochemistry-biological Remediation Technology For Heavy Metal Polluted Water And Soil

Waste water containing lots of heavy metals discharged by industry and mining enterprises and heavy metals polluted soil are main concerns for water and soil treatment at present.The key point is to develop water and soil remediation technology which is high efficient,cheap,stable,low energy consuming and environment friendly,as well as to promote and apply the technology.A bacteria station in laboratory was set up on basis of geo-chemistry engineering technology and microorganism recovering theory.Sulfate reducting bacteria(SRB)was selected,enriched as target strain by using soil,sediment and water samples collected in Xiawan area,Zhuzhou City.Bio-carrier of bacteria embedding technology was selected and microorganism embedding technology was developed.Remarkable result was got in removing high density Mn,Cd elements in waste industrial water by using SRB and bio-carriers.At the same time,research works on deep treatment of heavy metal Cd with manganese oxidize bacteria was done,mechanism of removing Cd by manganese oxidize bacteria was discussed and remarkable result was got.By taking advantages of geo-chemistry engineering technology and microorganism recovering technology,the thesis carried culture experiments for cultural lands polluted by heavy metals around industry and mining enterprises in Xiawa area,Zhuzhou City of Hunan province.Result of experiments shows that recovering effect can be improved by using SRB bacteria combined with minerals,and SRB can have remarkable effect in soil reparing.Main achievements of the thesis are as follows:1.Removing high density Cd and Mn in waste industrial water very efficiently to reach relevant national discharging standard.Density of Cd in discharged water can be lower than 0.1mg/L by using one level sulfate reduction organism biological filter when density of Cd in incoming water is 5mg/L,and it is in accord with requirement of Cd discharge in national water quality standard of discharging sewage to city sewer.Density of Cd in discharged water can be lower than 0.005mg/L and density of Mn can be lower than 0.lmg/L by using two level sulfate reduction organism biological filter when density of Cd in incoming water is 12mg/L.Density of Cd in discharged water can reach requirement of Cd for class ? and ? water in national"Environmental quality standards for surface water"(GB3838-2002).Density of Mn in discharged water reached limit requirement in standard of supplementary items for surface water resource of drinking water for centralized living.2.Removing Cd and Mn in waste water thoroughly to reach national drinking water standard.Density of Cd in discharged water can be lower than 0.005mg/L by using one level manganese oxidize biological filter when density of Cd in incoming water is 0.5mg/L,and it is in accord with requirement of Cd in Standards for drinking water quality(GB5749-2006).Density of Mn in discharged water can be lower than 0.1mg/L by using one level manganese oxidize biological filter when density of Mn in incoming water is 3mg/L.Density of Mn in discharged water reached requirement in Standards for drinking water quality(GB5749-2006).3.New phenomena was found by using manganese oxidize bacteria to remove Cd in slightly polluted water thoroughly.Removing mechanism was discussed generally to lay theoretical foundation for removing other heavy metal elements thoroughly in slightly polluted water by manganese oxidize bacteria.4.Content of Pb,Hg,As and Cd in Chinese cabbage and fast cabbage was lowered down dramatically.With the geo-chemistry and bacteria remediaton technology,contents(wet-weight)of Pb,Hg and As in fast cabbage were all lowered down to standard of limit of pollutant in food by adding 100gH(fabric)and 100ml microorganism(SRB)in every 2000g soil.Remediable effect is remarkable.It has obviously remediable effect on Cd,and remediable ratio of Cd can reach 38.71%,which will lower effectively the risk of exposure to heavy metal in serious pollution area.5.Costs are low.The remediation technology developed in this thesis lowers down the costs very much.For remediation of serious polluted soil,remediable costs for every 666 square meters(dig surface soil for 0.2m deep,i.e.133.2 cubic meters,and 1.5 tons per cubic meter)is only 15 thousand Yuan,which is much lower than the costs of soil remediation company in the market.The costs of treatment of heavy metals in industrial waste water mainly occur in engineering at beginning and design and setting up of equipment.The cost to set up a device with treatment capacity 40L/H is just 50 thousand Yuan.The costs for microbiological culture,operation and maintenance of water treatment system are pretty low,only for electricity consumption and man power.So the technology is quite worth of promotion from economic point of view.