Enhanced biodegradation of toluene and naphthalene in contaminated soils with the application of biosolids

Biosolid (BS) contains nutrients, organic matters, and microorganisms that are beneficial in facilitating the remediation of soil contaminated by polycyclic aromatic hydrocarbons (PAHs). In this study, BS applied to toluene and naphthalene-contaminated soils to investigate its effect on the enhancement of the biodegradation rate and removal efficiency. Experimental results indicated that the presence of BS enhanced the biodegradation rates of toluene and naphthalene in soils. The removal efficiency of toluene and naphthalene through biodegradation without applying BS was 15.2% and 20.4%, respectively, but increased to 96.0% and 97.9% with the addition of BS. The addition of BS enhanced the biodegradation rates of toluene and naphthalene in the contaminated soils was possibly resulted from the supplement of nutrients, trace elements, and degradable organic carbon. There was a maximum removal when the soil to BS ratio was at 1:0.5 (w/w).