Abstract

Spent engine oil is a common and toxic environmental contaminant. A preliminary investigation was conducted to determine soil properties (positive control), while spent oil-contaminated soil served as the negative control in a completely randomized experimental design featuring a 2*3*3*5 factorial combination. The analyzed parameters include pH, cation exchange capacity, moisture level, organic matter, organic carbon, particle composition, and soil temperature. Results indicated that soil physicochemical properties were significantly improved by using different animal waste as amendments at varying levels, regardless of time. The highest dose application (10% dung) yielded the best results. Goat dung at 10% (GD10) significantly increased soil pH (6.3), moisture level (17.0%), and clay (18.2%), but reduced soil silt (9.9%) and sand (72%) composition. Pig dung at 10% (PD10) significantly increased soil organic matter (13.48%) and organic carbon value (7.81%). Cow dung at 10% (CD10) significantly increased soil cation exchange capacity (5.09meq/100g) and temperature (31.9 °C), in addition to the organic matter (13.2%). Animal waste amendments had significant effects on soil microorganisms. The highest total viable counts (TVCs, 298.5cfu/mL) and total coliform counts (TCCs, 144.5cfu/mL) were recorded from 10% goat dung, while 5% cow dung produced the highest total fungal counts (TFCs, 122cfu/mL). Shigella spp. were present only in pig dung at 10% and cow dung at 3% and 5% while Escherichia coli, Enterobacter, and Shigella spp. were absent in control soil samples but present in all amended soils at all treatment levels. This cost-effective and simple method of soil remediation from spent engine oil may serve as a form of waste conversion into organic manure needed for plant growth.

Keywords:Spent engine oil; Cow dung; Pig dung; Goat dung; Soil contamination; Soil remediation