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Examination of Environmental Factors Affecting the Degradation of Pentachlorophenol Within a Soil Biopile

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  037043,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14178) @2003
Authors:   Michelle Miller, Glenn Stratton, Gordon Murray, Rob Gordon, Ali Madani
Keywords:   pentachlorophenol, biodegradation, soil, nutrient, amendment, temperature, moisture, aeration, biopile

Pentachlorophenol (PCP) is a toxic compound commonly found as a soil contaminant at wood preservation facilities. Laboratory studies were conducted to determine the effects of environmental parameters on the degradation of PCP by indigenous soil microorganisms. The objective of the first experiment was to determine the effect of selected nutrient amendments and incubation temperatures on the biodegradation of PCP in contaminated soil. This was accomplished by monitoring microbial populations, the concentration of PCP and the release of inorganic Cl- ions. The temperature factor consisted of three levels, 10, 15 and 20C. The three nutrient amendments chosen were an ammonium nitrate fertilizer, Municipal Solid Waste (MSW) compost and an aged dairy manure, along with a control (no nutrient additions). It was found that the temperature levels used had no significant effect on the microbial populations and the % PCP remaining in the soil. However, the nutrient factor levels did have a significant effect on the parameters measured. The dairy manure, ammonium nitrate fertilizer and the control experienced fluctuations in % PCP remaining in the soil and may have been due to the release of initially unextractable bound residues. It was found that the treatments that received the MSW compost amendment were significantly higher in bacterial and fungal populations. The% PCP remaining in the MSW amended soil decreased by 76%, while the concentration of inorganic Cl- ions increased in the soil. The objective of the second experiment was to determine the effects of supplemental aeration and moisture. The three moisture levels chosen were 40, 60 and 80% of the soils field capacity (FC). The three aeration levels used were: no supplemental aeration (control), 150 cm3 min-1 of supplemental aeration pumped through for 1 h d-1, and 150 cm3 min-1 of supplemental aeration pumped through for 2 h d-1. The moisture levels used were found to have no significant effect on the parameters measured with the exception of a significant increase in bacterial populations in treatments remaining at a 60% FC. In terms of the supplemental aeration factor it was found that in order to get a statistically significant decrease of PCP, a minimum of 150 cm3 min-1 of supplemental aeration for 2 h d-1 would be required. The results of this study were implemented into the construction of a soil biopile at a wood preservation facility.

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