Stability and Maturity of Composted Creosote Treated Wood Waste with an Aerobic Mixed Culture Augmented with the Thermophilic Actinomycete Thermomonospora curvata

Deepika Dave; Bopeng Zhang; Abdel E Ghaly
Creosote has been used as wood preservative and water proofing agent in railway sleepers and utility poles for centuries. However, creosote contains polycyclic aromatic hydrocarbons, phenolic compounds and other heterocyclic organic compounds which can cause potential contamination of soil and water, and threaten the health of human and animals. The bioremediation of phenolic compounds in composting bioreactor with a mixed aerobic culture augmented with the thermophilic actinomycete Thermomonospora curvata was investigated. The temperature profiles showed that the thermpophilic phase (>45˚C) was achieved and successfully maintained in both the control and the inoculated experiments due to the addition of used cooking oil as a bioavailable carbon source and urea as a nitrogen source. The moisture content decreased in both control and inoculated experiments because the water produced by microbial respiration did not compensate for the water lost as vapour with the exhaust gases. The final moisture contents of 42.9% and 39.1% for the control and the inoculated experiments were within the optimum range for composting. An initial increase in the pH was caused by the breakdown of organic nitrogen to ammonium which was then followed by a decrease due to the formation of organic acids from the decomposition of fats and grease and the loss of ammonium with the exhaust gases. The inoculated experiments achieved higher reductions of volatile solids, total carbon and TKN indicating a higher level of activity of microorganisms during the composting process compared with the control. As a result, higher degradation of phenolic compounds, cellulose and lignin were observed in the inoculated experiments. Different degradation rates were observed in the mesophilic and thermophilic stages of composting. The results indicated that the reduced products from both experiments have improved stability and phytotoxicity. The inoculation of cellulolytic-thermophilic actinomycete Thermomonospora curvata accelerated the bioremediation process and as a result higher degradation levels of phenols and lignocellulose were achieved.
Wood Waste; Composting; Bioremediation; Mesophilic; Thermophilic; Phenols; Cellulose; Carbon; Nitrogen; Maturity; Stability
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