Effect of Saw-dust on soils contaminated with waste lubricating oil

Abstract

Abstract In this study, we evaluated the influence of sawdust as biostimulatory agent on waste-lubricating oil site. To achieve this, two sites were contaminated with waste lubricating oil, with one of the site amended with sawdust and the other left to serve as control. This study was conducted during the dry season. Decreases in pH and percentage moisture content were used to monitor the metabolic activities between the amended and control sites. Both sites (amended and control) showed decrease in the pH values however the control site showed just slight decrease. The mean pH value obtained ranged between 7.68± 0.15-8.08± 0.57 for the amended and control while the mean moisture content (%) 38.3 – 48.6 respectively for the amended and control sites. We screened for fungal species that showed growth on sawdust amended site using waste lubricating oil as source of carbon/energy. This was done through conventional enrichment culture methods. The isolated fungal strains tentatively named as P1, P2, P3, P4 and P5 were identified by visual observation and micro-morphological technique. From the cultural, and morphological characterization and comparison with respect to the standard reference of fungi, the fungal species were identified as members Aspergillus niger, Rhizopus sp., Pénicillium sp., Aspergillus flavus and Mucor sp. Pure cultures of these fungal species were tested for their ability to utilize waste lubricating oil as carbon and energy source. The ability of these fungal species to use the waste lubricating oil was done by monitoring their physiological responses via Optical Density (OD) and pH gradient readings. The mean pH obtained range from 5.90-7.33 and the (OD) 0.715-1.978. The fluctuations in OD readings as well as pH values for the different microfungi may be due to variation in growth patterns of the different fungal species.