Determination of suitable TPH remediation approach via MANOVA and inferential statistics assessment

Soil contamination resulting from petroleum hydrocarbon contaminants poses a fairly substantial hazard to human health and the environment. Phytoremediation, land farming, and chemico–biological stabilization were used to treat total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) at a crude oil polluted soil site in Nigeria. A field pilot study was conducted by preparing nine cells with subcells attached to each serving as a control with an overall area of 1.53 m2. A complete block design method was used for the study. The prepared soil sample cells were divided into three groups with each group having approximately 300 kg of soil and delineated as low, medium, and high test plots. The low samples were spiked with 6.1 kg of crude oil, the medium samples were spiked with 12.2 kg of crudeoil, and the high samples were spiked with 18.3 kg of crude oil. Each row containing three cells with low, medium, and high concentrations were treated separately using the three treatment methods. The ratio of the soil sample to the organic amendment for the treatments was 2:1. The results showed over 90% degradation in the initial concentration of TPH and PAHs across different contaminant levels except in the control subcells where only 30% of degradation was recorded. Multivariate analysis of variance was employed to assess the significant difference in each treatment group while inferential statistics using a mean performance plot was used to ascertain the optimum treatment method. Land farming, chemico–biological stabilization, and phytoremediation ranked 1, 2, and 3, respectively. In conclusion, the three treatment methods employed all degraded the contaminants (TPH and PAHs) with land farming emerging as the best method.