Investigation of the Effects of Solpawa SBR-X TM Doses on Total Petroleum Hydrocarbon in Loam Soil at Different Depths

Abstract

Laboratory trials of environmental remediation products bring the hope of inventing such products to reality for many of today’s intractable environmental pollution conditions, paving the way for the field trials and subsequent large-scale field application. This laboratory study was conducted as the first phase of a 2-tiered adaptive trials of Solpawa® Bioremediation System (Solpawa-SBX) funded by the Nigerian Content Development and Monitoring Board (NCDMB). The study investigated the effectiveness of Solpawa-SBX, an indigenously formulated bioremediation agent comprising the liquid Solpawa®soil conditioner (SSC) and granular Solpawa®soil booster (SSB), in the bioremediation of petroleum hydrocarbon-contaminated loam soil. To do this, a total of twelve reactors of 1 m3(1000L) each were used (loam soil type and three Solpawa®addition levels). Each reactor was charged with 1000kg of each of the soil types and a condition of heavy spill was simulated by homogenizing the soil with 0.03132 m3(31.32 L) of crude oil, according to literature. The setup was left quiescent for five (5) days to incubate. The working solutions were prepared by diluting the SSC with water in the ratios of 1:4, 1:6, and 1:8. Each soil type in the reactor was then spiked with each cocktail of the SSC, excluding the soil in the control reactor. This was followed by the addition of 0.004 m
3(4 L) of water after 48 hours and the SSB after another 72 hours. Afterwards, mixing and watering was carried at 2 days interval for a period of 40 days. Selected physiochemical properties of the initial soil conditions and the fertilizer values of the SSC and SSB were determined using standard analytical protocols with regular monitoring and evaluation up until the cessation of treatment. Result showed that the fertilizer values of the SSC and SSB far exceeded the fertilizer value of 3:2.5:0.5 (N:P:K) recommended in the literature for materials with remediation potential. The total petroleum hydrocarbon (TPH) of the contaminated soil dropped from an initial 20,406.9 mg/kg at commencement of treatment to 681.01
mg/kg (representing 96.4% TPH reduction) at the depth of 3 cm after 40 days of treatment with the SSC working solution of 1:4 (i.e., the highest SSC addition level). Overall, TPH reduction across the reactors reduced with increase in depth and decrease in the level of SSC in the working solution. Analysis of variance (ANOVA) results also revealed significance difference in treatment means at 5% significance levels. It is, therefore, suggested that the SolpawaSBX can be used as remediation agent for degrading TPH concentration for petroleum contaminated loam soil.