Parameters optimization of treating oily soil by windrow composting

To study the factors that can result in effective degradation of oil-contaminated soil by windrow composting, we performed single-factor experiments to research the ranges of oil concentration, temperature, soil moisture content, organic matter content, soil C/N, and microbial inoculum concentration. Considering the degradation rate of petroleum hydrocarbon as the evaluation index, the optimum engineering parameters were determined by performing orthogonal experiments. An orthogonal design of about L₉(3⁴) by using an oil concentration of 2%, temperature of 35℃, and soil C/N as 10:1 as control variables and considering the microbial inoculum concentration (X), organic matter content (Y), and soil moisture content (Z) as the variable factors, the best combination for effective degradation of oil-contaminated soil would be X₂Y₂Z₃ on the condition that microbial inoculum concentration is 5×10⁹ cfu·kg^-1, organic matter content is 5%, and the soil moisture content is 60%.