Modelling for the phytoremediation of crude oil polluted soil using Cassava and Yam waste peels

Philip Eruni Uku

Abstract

The objective of this study is to investigate the extent of degradation of soil contaminated with petroleum hydrocarbons by utilizing the remedial potential of cassava peels and yam peels as amendment additives. To achieve this, a baseline study was conducted to assess the physicochemical properties of the contaminated soil, using appropriate analytical methods. For the experimental phase, homogenized soil samples (1000 g each) were amended with 10.53g of cassava peels and 107.48g of yam peels to achieve a concentration of 0.2%. Additionally, to establish a concentration of 0.4% nitrogen, 23.87g of cassava peels and 243.54g of yam peels were added. Different microorganism experiments (labeled A, B, C, and D) were set up, alongside a control group (lacking the aforementioned additives). Throughout a six-week incubation period, the microorganism experiments were aerated three times a week. Samples from each microorganism were collected at two-week intervals for subsequent analysis. The results revealed a rapid decrease in TPH concentration within the first two weeks of incubation, which continued to decrease progressively over subsequent sampling periods. This reduction in TPH concentration corresponded to an increased rate of removal of hydrocarbon compounds. Notably, Sample D exhibited the highest rate of TPH removal, while the control group (Ct1) displayed the lowest. Furthermore, microbes established with a nitrogen concentration of 0.4% demonstrated a greater rate of nitrogen consumption compared to those with a 0.2% nitrogen concentration. The combined approach of bio-stimulation appears to be an effective method for facilitating the removal of TPH components from contaminated soil.