Total Hydrocarbon Degradation of Crude Oil Contaminated Soil using Mixture of Poultry Manure and Biochar: Optimization of Amendment Process Variables

Abstract

In this work, farmland soil contaminated with crude oil was remediated with a mixed amendment material
which comprised of poultry manure and biochar (prepared from corn cob). The soil, poultry manure and biochar
were characterized in terms of physico-chemical properties using standard techniques. The amendment experiment
was designed employing the central composite design of response surface methodology for three variables at five
levels. The process variables considered and their range of values are composition of amendment material (10 –
80% poultry manure), level of application of amendment material (2 – 10%) and duration of amendment (2 – 12
weeks). The values of the physico-chemical properties, particularly the organic matter, nitrogen and phosphorous of
the amendment material were markedly higher than in the contaminated soil and suggest their potential to facilitate
contaminant degradation. Analysis of total hydrocarbons degradation of the soil after amendment showed that
composition of amendment and duration of amendment had significant effects on the total hydrocarbon content of
the soil. The optimum total hydrocarbon content degradation of 745.69 mg.kg-1 was obtained with amendment
composition of 65.8% poultry manure (34.2% biochar), level of application of amendment of 8.4% with respect to
the total hydrocarbons content of the contaminated soil and duration of amendment of 10 weeks and corresponded
to about 80% total hydrocarbon degradation. The correlation and high regression coefficients of the experimental
and predicted values of total hydrocarbon content showed that experimental data are in agreement with the
predicted data and suggested that the mixture of poultry manure and biochar have the potential to effectively
degrade hydrocarbons present in contaminated soil.