Optimization of nutrients requirements for bioremediation of spent-engine oil contaminated soils

Abstract

This paper presents a preliminary investigation of the optimum nutrients combination required for bioremediation of spent-engine oil contaminated soil using Box-Behnken-Design. Three levels of cow-manure, poultry-manure and inorganic nitrogen-phosphorus-potassium (NPK) fertilizer were used as independent biostimulants variables; while reduction in total petroleum hydrocarbon (TPH) and total soil porosity (TSP) response as dependent variables were monitored under 6-week incubation. Ex-situ data generated in assessing the degree of biodegradation in the soil were used to develop second-order quadratic regression models for both TPH and TSP. The two models were found to be highly significant and good predictors of the response fate of TPH-removal and TSP-improvement, as indicated by their coefficients of determination: R 2 = 0.9982 and R 2 = 1.000 at p ≤ 0.05, respectively. Validation of the models showed that there was no significant difference between the predicted and observed values of TPH-removal and TSP-improvement. Using numerical technique, the optimum values of the biostimulants required to achieve a predicted maximum TPH-removal and TSP-improvement of 67.20 and 53.42%-dry-weight per kg of the contaminated soil were as follows: cow-manure -125.0 g, poultry-manure -100.0 g and NPK-fertilizer -10.5 g. The observed values at this optimum point were 66.92 and 52.65%-dry-weight as TPH-removal and TSP-improvement, respectively.

Effect of spent engine oil contamination on the soil properties in selected automobile mechanic villages in Enugu, Enugu State, Nigeria

“…Point 2 was a green uncontaminated agricultural land about 500 m away from the reference point, and this served as the control. Composite samples were collected at each sampling point at the depths of 0–30 cm (topsoil) and 30–60 cm (subsoil), respectively, using soil auger (Iren & Ediene, 2017; Johnbosco et al., 2020; Ogbeh et al., 2019; Nwinyi & Olawore, 2017; Okonokhua et al., 2007; Okoro et al., 2013; Ramadass et al., 2015; Udochukwuka & Agwu, 2014;). Sixteen (16) composite samples were collected in all, four (4) per location (automobile mechanic village).…”

“…The total organic carbon (TOC) was determined according to the Walkley and Black (1934) method using acidified dichromate, while total organic matter (TOM) was calculated by multiplying the value of determined TOC by 1.729; total nitrogen (TN) was determined using the Macro‐Kjeldahl method (Bremmer & Mulvaney, 1982); available phosphorus was by Bray and Kurtz (1945) I method; total sulfur was determined by a colorimetric methylene blue method after dry ashing oxidation of total sulfur to sulfate and reduction of sulfate to sulfide (Johnson & U1rich., 1959); soil bulk density (BD) was determined using the core method of Grossman and Reinsch (2002); soil particle density (PD) was measured according to the method of pycnometric with density bottle (volume 50 mL). The total soil porosity (TSP) was measured by finding the ratio of pore spaces to the total soil volume (Ogbeh et al., 2019). Heavy metals were determined by AAS using the LAAS‐210 model after digestion of soil samples with perchloric and nitric acid (Iren & Ediene, 2017; Johnbosco et al., 2020; Okonokhua et al., 2007; Okoro et al., 2013; Udochukwuka & Ifeanyi, 2014).…”

“…The concentration of automobile workshops in mechanic villages is very likely to increase these effects. Several researchers have studied the effect of SEO discharge on properties of soil in automobile mechanic workshops or clusters of automobile workshops generally referred to as mechanic village across Nigeria (Iren & Ediene, 2017; Johnbosco et al., 2020; Ogbeh et al., 2019; Okonokhua et al., 2007; Okoro et al., 2013; Udochukwuka & Agwu, 2014; Zitte et al., 2016). The effects of SEO contamination on soil properties according to these studies were (1) decrease in soil quality; (2) increased pH values, organic carbon, total nitrogen, and available phosphorus at the point of discharge of the SEO; (3) impaired soil geotechnical properties; (4) adverse effect on plant height, root number, and root length of maize plants grown in the contaminated soils; (5) a higher concentration of heavy metals at the topsoil which exceeded the established intervention, target, and allowable limits set for soils in Nigeria and some other countries.…”

Identifying New ‘Hotspot’ Heavy Metal Contamination in Industrial Zone Soil

“…Concentrations of PCB and heavy metals are greater than measured values during other surveys [14][15][16][17][18][19].…”

“…The degree of soil load is calculated according to the Rulebook [18] (Table 5). Average values degree of soil load show that V class is a land of very high load, with degree of soil more than 200%.…”