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Compost bioremediation of
hydrocarbon-contaminated soil inoculated with organic manure
Harrison Ifeanyichukwu Atagana
Institute for Science and Technology Education, University
of South Africa,
Pretoria, South Africa.
E-mail:
atagahi@unisa.ac.za.
Accepted 10 April, 2008 |
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Contaminated soil (FAO: Lithosol) containing >380 000 mg kg-1
total petroleum hydrocarbons (TPH) was bioremediated by
composting. The soil was inoculated with sewage sludge and
incubated for 19 months. The soil was mixed in a ratio of
1:1 (v/v) with wood chips. The soil-wood chips mixture was
then mixed in a ratio of 4:1 with sewage sludge. Compost
heaps were set up in triplicates on wood pallets covered
with double layers of nylon straw sheets. Control
experiments which contained the contaminated soil and wood
chips but without sewage sludge were set up in triplicate.
Moisture, temperature, pH, ash content, C:N ratio of the
compost mixture and TPH of the soil was monitored monthly.
The concentrations of selected hydrocarbons in the
contaminated soil were measured monthly during the
incubation period. Temperature rose to about 58°C in the
sewage sludge compost within two months of incubation, while
temperature in the control fluctuated between 15 and 35°C
throughout the incubation period. Total petroleum
hydrocarbons (TPH) was reduced by 17% in the control
experiments and 99% in the sewage sludge compost at the end
of the incubation period. The concentrations of most of the
selected hydrocarbon components were reduced by up to 100%
within the same period. Microbial activities were shown to
correlate with the reduction in hydrocarbon contents of the
soil.
Key words:
Bioremediation, composting, PAHs, sewage sludge, soil. |
