| Polychlorinated biphenyls (PCBs) are one kind of important organic-chlorinated pollutants in the environments due to their physical and chemical stability and recalcitrant degradation. In this paper, Enterbacter sp.LY402, which has been proved to be effective in the aqueous growing-cell system, was researched to biodegrade PCBs in PCBs contaminated soil under the condition of surfactant-sucrose ester.The experimental results were as follows.(1)The methods to deal with soil sample and calculate the residual concentration and of PCBs were established. Hexachlorobenzene was introduced as internal standard of recovery.(2)In the aqueous system, the LY402 showed the similar ability to degrade low-chlorinated PCBs congeners when the absorbance of the cell of LY402 was 0.2, 0.5, 1.0 or 2.0 at 600 nm, respectively. However, the highest ability to transform high-chlorinated PCBs congeners (the NO. of chlorine≥6) appeared at OD6002.0.(3)LY402 could coexist with the indigenous bacteria and degrade low- and high-chlorinated PCBs congeners in the condition of 10%, 50%or 100% soil humidity. Highest ability of degradation was occurred when the soil humidity was 100%. The degradation rates were 54.76% and 52.87% after 10 and 20 days of incubation, respectively.(4)In the condition of 30% soil humidity, PCBs were degraded by 23.14% and 46.60% in serile soil and 46.60% in non sterile soil after 20 days of incubation.(5)In the practical soil contaminated by transformer oil, degradation rate was 19% after 20 days of incubation,which was lower than that of Aroclor standard samples. We postulated that PCBs were encircled by other types of hydrocarbon of transformer oil which counteracted the contact with LY402. That decreased the ability of LY402 to degrade PCBs.This paper presented that Enterbacter sp.LY402 was able to not only coexist with indigenous bacterium but also bio-remediate both low- and high-chlorinated PCBs. This is an advantage in PCBs-contaminated soil amendment in the present research.
|
PDF Full Text Request