Bioremediation of pentachlorophenol-contaminated soil by bioaugmentation using activated soil

Area of Science:

• Environmental Microbiology
• Bioremediation
• Soil Science

Background:

• Pentachlorophenol (PCP) is a persistent organic pollutant found in contaminated soils.
• Effective bioremediation strategies are needed to address PCP pollution.
• Bioaugmentation using microbial consortia shows promise for pollutant degradation.

Purpose of the Study:

• To evaluate activated soil as a bioaugmentation method for aerobic biodegradation of pentachlorophenol (PCP) in contaminated soil.
• To assess the production and efficacy of a PCP-acclimated microbial biomass.
• To determine the long-term stability and activity of the bioaugmentation agent.

Main Methods:

• A soil slurry bioreactor was used to cultivate a PCP-acclimated microbial consortium attached to soil particles (activated soil).
• The bioreactor's effectiveness in producing PCP-degrading bacteria was monitored.
• Activated soil biomass was used to bioaugment a PCP-contaminated sandy soil lacking indigenous degrading microorganisms.

Main Results:

• The bioreactor successfully produced a PCP-acclimated biomass, increasing PCP-degrading bacteria from 10(5) to 10(8) cfu/g within 30 days.
• Mineralization of PCP was confirmed by chloride accumulation.
• The activated soil consortium tolerated high PCP concentrations (up to 250 mg/l) and remained active for weeks to months at different temperatures.
• Bioaugmentation achieved a 99% reduction in PCP concentration (from 400 mg/kg to 5 mg/kg) in 130 days.

Conclusions:

• Activated soil is an effective bioaugmentation agent for the aerobic biodegradation of PCP in contaminated soils.
• The soil-attached microbial consortium demonstrates high PCP tolerance and stability.
• Bioaugmentation with activated soil significantly reduces PCP levels in previously non-degrading soils.