Study On Bio-chemical Remediation Technology For Organic Pollutants In Urban River Contaminated Sediment

Along with external source of pollution in the municipal river treatment,contaminated sediment remediation has recently been paid more attention as theimportant part of water pollution treatment. Organic pollutants, especially therefractory organic pollutants, include TPH and PAHs can be bioaccumulatedthrough the food chain and pose health risks to wildlife and human consumers.In-situ bioremediation and chemical stabilization has been commonly used inorganic polluted sediment remediation. In-situ bioremediation has been greatlyattracted for its lower cost, efficiency, and less interference in ecologicalenvironment, although it can not solve the additional effections, such as blacksmelly sediment. In-situ chemical stabilization has successfully recovered the blacksmelly sediment, but less efficiency in remediate organic pollutants. So acombination of biological and chemical remediation methods may be necessary forthe complicated sediment contamination. Bio-chemical remediation of sedimentcontaminated by organic pollutants has been discussed in this paper, study on boththe removal rate of organic pollutants,and the environmental effects, assessing andseeking a solution.Biostimulation is a co-metabolic process where we add various forms ofnutrients and electron acceptors that stimulate the growth of indigenous microbesthat favour degradation. The species and dosage of the co-substrate is important inthe co-metabolic method of biostimulation technology. The experiments of thebiostimulation indicate that, the addition of sodium acetate, methanol and sodiumacetate+methanol can enhance the removal rate of TPH、PAHs and TOC, the mosteffective co-substrate is sodium acetate dosaged in100mM, which could reach theremoval goals of TPH and PAHs in77days cultivation; however, the anaerobicdegradation may cause environmental contamination issues, such as the black andodorous sediment or overlying water, the worse of the reduction state of sedimentand overlying water, sediment suspension, secondary pollution with overlyingwater.In the bio-chemical remediation of a combination of sodium acetate andcalcium nitrate, calcium nitrate is added to the sediments after the effection of biostimulation worked out. This bio-chemical remediation experiments indicate:the removal rate of the organic pollutants in the method of a combination of sodiumacetate and calcium nitrate is higher than either the individual addition of sodiumacetate and individual addition of calcium nitrate; calcium nitrate can play a role inmany aspects,such as repair the black sediment, improve reduction state ofsediment and overlying water, although it can not overcome the disadvantage in thesulfuretted hydrogen removal.The experiments of the bio-chemical remediation of organic pollutantscontaminated sediment in the method of a combination of sodium acetate、iron andcalcium nitrate indicate: bio-chemical remediation is more efficiency thanbioremediation in the the removal of the organic pollutants, and in the bio-chemicalremediation, sodium acetate biostimulation still play the role of removal therefractory organic pollutants, while iron and calcium nitrate also take part in theremoval, the combination of the reduction of iron and the oxidation of calciumnitrate perform a great job also in remediation the refractory organic contaminatedsediment, but in reduction the air and overlying water’s contamination risk.