Recent technology on bio-remediation of POPs and persistent pesticides

Abstract

Clean-up technology for contaminated soil and water with persistent organic pollutants (POPs) and other pesticides is required. A new aerobic pentachloronitrobenzene (PCNB)-degrading bacterium, Nocardioides sp. strain PD653, was isolated from an enrichment culture in an original soil-charcoal perfusion system. Strain PD653 also degraded hexachlorobenzene (HCB) with a liberation of chloride ions to CO2 under aerobic conditions. It is the first aerobic bacteria capable of mineralizing HCB. Moreover, an aerobic dieldrin-degrading fungus, Mucor sp. strain DDF, was isolated from soil to which endosulfan had been applied annually for many years. Strain DDF degraded dieldrin to 1.01 μM from 14.3 μM during 10-day incubation at 25°C. On the other hand, the application technology remains inadequate for remediating contaminated sites. Therefore, we developed a method to introduce the degrading-bacterial consortium into contaminated soil using a special charcoal material that enriched the soil with a methylthio-s-triazine degrading bacterium and the chloro-s-triazine degrading bacterial consortium CD7. For in situ bioremediation study, the enriched charcoal with CD7 was used at a contaminated site with simazine. The material was effective for preventing penetration of simazine into subsoils and nearby aquatic environments for approximately two years.