Bioconversion of Crude Oil Production Sludge into Soil Conditioner Using Sawdust as Organic Amendment

Abstract

Nigeria is a major oil producer in Africa and the World, with significant oil exploration and production activities. These vast oil activities pose a challenge in disposal of oily sludge. The objective of this study was to adopt the principles of biotechnological wastes - to - wealth conversion for the utilization of abundant oily sludge waste. Various sawdust/oily sludge (SD/OS) ratios were used for composting for 21 weeks with sawdust (SD), oily sludge (OS) and untreated soil used as controls. Total heterotrophic bacterial count for SD/OS ratios used ranged between 7.4 and 17.4 x 106 cfu/g and between 6.2 and 18.4 x 106 cfu/g for controls. Hydrocarbon utilizing bacterial counts ranged between 5.9 and 9.0 x 106 cfu/g for SD/OS ratios and between 5.4 and 5.8 x 106cfu/g for controls while total fungal counts for SD/OS ratios used ranged between 4.5 and 5.0 x 107cfu/g and between 3.25 and 5.50 x 107 cfu/g for controls. Hydrocarbon utilizing fungal counts ranged between 3.50 and 4.25 x 107 cfu/g for SD/OS ratios and between 3.00 and 5.25 x 102cfu/g for controls. Predominant bacterial genera isolated were Micrococcus, Flavobacterium, Pseudomonas,Acinetobacter and Staphylococcus while fungal genera were Aspergillus, Penicillium, Saccharomyces and Candida. Nutrient levels for nitrogen, potassium, phosphorus, magnesium, iron and zinc reduced between weeks 0 – 21. Microbial counts increased between weeks 0 and 7 and decreased between weeks 14 and 21 of composting for SD/OS ratios, SD and OS. SD/OS ratios 1:1, 4:1, 8:1, 16:1 caused the most positive significant effects on plant growth. This research shows that oily sludge from oil activities can be converted to soil conditioner to enhance agricultural productivity and thus ensure food security.