Abstract
Creosote is used for preservation of railway ties and timbers, electric utility poles, marine and foundation piling, fences and garden furniture. Creosote-treated wood waste may cause potential contamination of soil and water if they are not disposed properly. Creosote contains over 300 organic compounds including polycyclic aromatic hydrocarbons, phenolic compounds and heterocyclic organic compounds, many of which are toxic to human and can cause damage to kidney, liver, eyes and skin. The feasibility of using a composting technique inoculated with the cellulose degrading actinomycetesThermobifidafusca as a mesophilic/thermophilic bioremediation option to degrade phenolic compounds in creosote treated wood waste was evaluated. The temperature profile of bioremediation process clearly identified mesophilic and thermophilic phases in both experiments. Different degradation rates were observed in the mesophilic and thermophilic phases. Fluctuations of pH was observed in both experiment as the result of the breakdown of organic nitrogen to ammonium in the first week and the formation of organic acids and the loss of ammonium with the exhaust gases in the latter stage. The moisture content decreased in both trials because of the net loss of water with the exhaust gas. Both experiments achieved similar reductions in total carbon and TKN, volatile solids and phenolic compounds, cellulose and lignin indicating similar levels of microbial activities during the composting process. The stability and maturity of the final products were also similar. The inoculation of the cellulolytic-thermophilicactinomycetesThermobifidafusca did not manifest observable differences in degrading cellulose, lignin and phenolic compounds compared with the control.
Highlights
Creosote has been the compound of choice for use as a wood preservative and waterproofing agent for railway ties, cross ties, bridge timbers, utility poles, marine and foundation piling and other outdoor agricultural and recreational facilities [1,2,3,4,5]
The main aim of this study was to evaluate the possibility of using a composting process augmented with the actinomycete Thermobifida fusca as a thermophilic bioremediation option for the degradation of cellulose and phenolic compounds in creosote treated wood waste.The focus in this study was on phenolic compounds because extensive studies have been conducted on polycyclic aromatic hydrocarbons (PAHs), but few reports were found in the literature on phenolic compounds
The volatile solids content decreased to 775 ± 12 and 776 ± 14 g/kg material with reductions of 3.7% and 3.6% for the control and the inoculated experiments, respectively
Summary
Creosote has been the compound of choice for use as a wood preservative and waterproofing agent for railway ties, cross ties, bridge timbers, utility poles, marine and foundation piling and other outdoor agricultural and recreational facilities [1,2,3,4,5]. Bestari et al [7] reported that the life expectancy of marine wood pilings was extended from 10 to 40 years and 75% of creosote was still left in the treated wood at the end of this period. The presence of the toxic PAHs and phenolic compounds make creosote treated wood harmful for the environment at the end of its service life and direct or indirect human exposure to creosote treated wood may cause damage to kidney, liver, bladder, eyes and skin carcinogen [3]. Current disposal practices of creosote-treated wood waste such as incineration and landfill are problematic because of the release of components such as PAHs and furans and the possible migration of contaminants can cause soil, groundwater and surface water deterioration [4].
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