Bioremediation of biodiesel and biohydraulic oils by food waste composting

Bio-based hydraulic oils and biodiesel fuels are increasingly used on farms, in business and industry. While petrochemical spills and disposal of similar fluids create hazardous waste concerns, these bio-based products are generally considered more environmentally friendly. This study investigated the biodegradation of these compounds in composting systems, both directly as a disposal method for used oils or fuels, and blended with contaminated soils to simulate clean-up of leaks and spills. Two studies are reported here. The first, a bench-scale composting trial of compost + 20% soil (wet basis, w.b.), included three fuel contamination treatments, each applied at 30% of the soil fraction: 100% biodiesel (B100), 100% petroleum diesel (D2), or a blend of 20% biodiesel with 80% petroleum diesel (B20), with all three treatments having a final contaminant concentration of 6% in the compost and soil mixture. The second study was a lab-scale composting trial of compost + 10% (w.b.) either new or used bio-based hydraulic fluid vs. mineral hydraulic fluid. Results demonstrated that the bio-based products degraded much more rapidly than conventional petrochemical fluids, with about 86% of the recovered content of bio-based hydraulic fluid degrading within three weeks, versus only 34% of the conventional oil. Similarly, about 90% of B100 degraded after three weeks, while approximately 75% of the B20 blend degraded. Composting appears to have considerable potential for bioremediation and disposal of these bio-based products in agricultural and industrial settings.