In situ microbial bioremediation of obsolete pesticides at their disposal sites

Soil pollution by pesticides is a global problem in many countries, including Kyrgyzstan. Currently, 50 storage facilities for obsolete banned pesticides exist, severely threatening the surrounding populations and environment. In this study, in situ bioremediation technology was used to remove pesticide contamination from soil around the storage facilities. Three conditions were tested: application of fertile soil and bioproduct, application of fertile soil and no bioproduct (Control 1), and application of fertile soil and no bioproduct (Control 2). An aerobic bioremediation approach was used: the treatment was applied directly to the contaminated soil. For the bioaugmentation, three selected active degrading bacterial species were used: Stenotrophomonas sp. (Ps-B strain), L. fusiformis (SA-4 strain) and E. cloacae (SB-2 strain). Regular aeration, loosening and watering were performed during the subsequent months to create the conditions required to activate the local microflora and the degrading activity of the bacterial species in the bioproduct. The bioproduct of three active bacteria species has demonstrated a high pesticide decomposition effect. The pesticides were degraded from 85.6 to 99.0 ± 0.05 within six months of initiating the bioremediation process. The efficiency of the degradation process depended on optimum atmospheric conditions, that is, temperature, pH, and moisture content of the soil. Our study recommends using the agrotechnical and biotechnological approach for moderately pesticide-polluted soils and pesticide storage areas.

Keyword: aerobic active degradative bacteria; agrochemical improvement of polluted soils; bioaugmentation and bioremediation technology in situ; obsolete pesticides