Remediation Of Sediment Contaminated By Polycyclic Aromatic Hydrocarbons (PAHs)

The experiments were performed in reactors according to water seal principleand1.2L jars, to study the biodegradation efficiency of yeasts and denitrification,surfactants TW-80, and the different adding means of electron accetor NO₃^-. In orderto provide theoretical basis and technical support for in suit bioremediation of rivercontaminated sediments. The results are as follows:The indigenous microorganisms in the control sediment could degradate all kindsof PAHs （phenanthrene, anthracene, fluranthene, pyrene）. After360days, thedegradation rate of pyrene reached to68.24%and it was the highest, the degradationrate of anthracene was only55.18%and which was the lowest. The results showedthat different strains had different effects to the same kind of PAHs, and the effects todifferent PAHs were various by the same strain. The degradation efficence of3-ringPAHs were much higher than that of which without the strains adding, especially thedegradation rate of phenanthrene reached to90%. In addition, temperature is one ofthe important effectors for biodegradation activity.In reactors, TW-80could improve the bioavailabilities of PAHs and speeded upthe degradation rate on the beginning of the experiments. But, TW-80at highconcentration can inhibit the activity of microbes. When the congcentration of TW-80was800mg/L, the degradation rate of TPAHs was the highest （76.77%）. Addition ofTW-80inhibited the activity of microbes in all jars.Injection different strains and electron acceptor NO₃^-by different means, haddifferent effects to4kinds of PAHs. Injection of yeast and NO₃^-could speed up thedegradation rate of all PAHs, and the effects of injection of NO₃^-by3batches wasbetter than that by one-time. Injection of denitrifying bacteria and NO₃^-had a littleeffecet on phenanthrene, had big effects on fluoranthene and pyrene. After360days,the degradation of fluoranthene and pyrene was25.14%,24.47%higher than that ofcontrol, respectively. Addtion NO₃^-promoted the degradation of PAHs more thanTW-80, fluoranthene was the most obvious. After360days, the degradation offluoranthene was over82%with NO₃^-, however degradation of fluoranthene withTW-80was less than63.40%.After360days, the concentration of PAHs decreased to0.3μg/L, the degradation rate of TPAHs was over92%, the degradation rate of NO₃^-was over95%, in theoverlying water. And fully proved the significance of sediment remediation to thequality of rivers.