Biodegradation of petroleum hydrocarbons of bottom sludge from crude oil storage tanks by in-vessel composting

The feasibility of aerated in-vessel composting of sludge waste from crude oil storage tanks for total petroleum hydrocarbons (TPH) removal was investigated. Immature compost as an amendment for supplementing nutrients, organic matter and microbial activity was added to the sludge. The ratios of sludge to compost were 1:0 (as control), 1:2, 1:4, 1:6, and 1:8 (as dry basis) at a C:N:P ratio of 100:5:1 and 55% moisture content for a period of 10 weeks. TPH removal was 67%, 73%, 75%, and 80%, respectively. The results of the control reactors indicated that the main mechanism of TPH removal in the composting reactors was biological. In-vessel composting by addition of immature compost as amendment is a viable choice for sludge remediation.