Iranian Journal of Chemical Engineering (IJChE)

Abstract In recent decades, large amounts of hydrocarbon derivations have contaminated the environment due to industrial developments and neglecting the environmental issues. In this study, the ability of biological removal of hydrocarbon pollution from contaminated soil around Sarkhun gas refinery was investigated. This study was done for seven samples with three different nutrient ratios and by moisture controlling and continuous aeration. During experiments, concentration of Total Petroleum Hydrocarbon (TPH) was measured. Results showed that with a nutrient ratio of 100:5:1 for C:N:P during an 18-day remediation period, the mean contaminant removal was about 50%. By using these results a practical plan was suggested for running in real scale situations. Developing a model was done by considering the Monod model as microbial growth model. Results showed good accordance to empirical data.

Abstract Contamination of soils with nitroaromatic hydrocarbons, due to their toxic effects, is one of the environmental issues. Therefore, the purpose of this study is to examine para-nitrophenol (PNP) biodegradation in a microcosm consisting of kaolan clayey soil by A. faecalis, the superior bacterium among the four examined bacterial species. Preliminary experiments were performed in slurry phase to investigate biodegradation of PNP by A. faecalis in shaking flasks at initial concentrations of 25 and 50mgkg-1  which resulted in 72 and 57% PNP removals after 20 days, respectively. To identify the effective factors on PNP biodegradation, experiments were carried out in shake flasks at various levels of eight factors, i.e. PNP, glucose and yeast concentrations, temperature, soil-water ratio, initial pH, inoculum size as well as PNP concentration in pre-exposure based on Plackett-Burman design method. Results showed 20.9 up to 75.5% PNP removal in soil slurry after 12 days within the design space. Analysis of variance revealed that temperature, inoculum size, yeast extract concentration, pH and soil-water ratio are the most effective factors on PNP biodegradation, respectively.