Managing physicochemical parameters in compost systems to enhance degradation of petroleum wastes from a sludge dam

3on wooden pallets overlaid with nylon fibre sheets. Temperature, moisture, electrical conductivity (EC), pH, total carbon, total N, heterotrophs and respiration of compost microorganisms were monitored in each pile. Moisture was maintained at between 60 and 70% field capacity. Temperatures reached a mean of 63°C in the compost containing manure and sawdust. The C:N ratio of composts changed significantly during the composting process, reaching 100:41 (sawdust+manure) 100:39 (hay+manure) and 100:31 (woodchips+manure). Respiration of compost organisms rose from 1490 to 3850 CO2 (µg)/dwt/day in the sawdust+manure compost. Total petroleum hydrocarbons (TPH) decreased by between 52 and 66% in the composts and concentrations of selected polycyclic aromatic hydrocarbons (PAH) by between 78 and 100%. The Bacillus, Pseudomonas, Arthrobacter and Staphylococcus species were predominant in all the experiments and all temperature regimes.