Preliminary experiments using a range of bulking agents, moisture contents, nutrients, cosubstrates and inocula were undertaken to determine suitable ingredients for the successful composting of a heavy oil refiner sludge. The best ingredients were then chosen for a detailed study of the CO2 evolution rate and Total Petroleum Hydrocarbon (TPH) reduction versus time during the composting process. The initial TPH content of the refinery sludge was found to be 30% (mainly C-15-C-30), two thirds of which were saturates and aromatics that were thought to be biodegradable. The results show a significantly higher TPH reduction using Solv-II (55% reduction) as a bulking agent/nutrient source compared to heat-treated peat moss and barley straw (both at 30% reduction). The CO2 evolution was high with Solv-II and barley straw indicating the presence of high microbial activities in those composters. [References: 19]
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