| The accumulation quantity of petroleum hydrocarbon contamination in the environment increases day by day and has been a serious potential threat to the human health and ecosystem security. Bioremediation has gradually become an safe and effective remediation technology to hydrocarbon contamination because it is low-cost treatment and has no secondary pollution. The microbe can transform petroleum hydrocarbons into less toxic compounds by its cometabolism, and the microorganism during composting has a high activity, so the compost technology has a great potential development to deal with petroleum pollutant.Composting process of cattle manure spiked with petroleum hydrocarbons were characterized under different temperatures(20℃and 50℃) and pollutant contents(0,1%,5% and 10%). With the method of sampling and measurement in definite times, the degradation effect of total petroleum hydrocarbon (TPH) by microorganisms was found under different temperature during composting, including the content changes of saturated hydrocarbons (SH), aromatics hydrocarbons (AH), polar fraction (PF) and polycyclic aromatic hydrocarbons (PAHs); the variations of colonies number, enzyme activity and microbial diversity was also observed for comparing toxic effect of TPH concentration, to get oil degradation bacterium with good work. The main conclusions are as the followings:(1) The affecting factors for TPH detection were analyzed, the suitable analysis condition of ultrasonic wave-soxhlet extraction-weight method was determined by orthogonal experiment as the following:ultrasonic power is 60 W for 10 min, the dosage of extracting agent is 125 mL for 6 h.(2) The pH decreased but the high oil content after composting. The initial C/N ratios of raw materials were between 25 to 35, then gradually reduced to be below 20 during successful composting.(3) The highest TPH removal rate 42.2% was found at 1% TPH concentration and 50℃after 21 d. The contents of SH declined, AH decreased first and increased at the end of composting, while PF behaved the same as that of AH at 20℃, but decreased in the end at 50℃. The 3 and 5-ring PAHs decreased and 6-ring PAHs increased at 20℃, and 6-ring PAHs increased first and decreased at 50℃.(4) Because the number of microorganisms decreased with the increase of composting temperature, the catalase activity (CA) and polyphenol oxidase activity (POA) were inhibited under higher temperature and pollutant content, while dehydrogenase activity (DA) increased. These enzymes can promote the decomposition of petroleum hydrocarbon.(5) The microbial diversity increased with higher 50℃incubation temperature as shown by denaturing gradient gel electrophoresis (DGGE) analysis. It showed that the composting can help the stability of microbial community. But because of the biological toxicity, the crude oil inhibited microbial diversity.(6) Six different strains were isolated from compost with oil. The experimental results of TPH degradation, (26.33±2.15)%～(64.18±4.88)%, showed that the bacterial strains had marked degradation ability. They were helpful for the restoration of the petroleum contaminated soils.(7) The bioremediation experimental results of Dagang oilfield showed that the six strains of bacterias with certain plants had a good degradation effect with soil contaminated by crude oil. The maximum of removal rate was (75.7±7.55)% after five months. The amount of PAHs also had obviously decreased with the maximum 82.75%.The experimental results showed that, wirh reasonable control factors, composting can achieve the purpose of petroleum degradation by microorganisms cometabolism, and the effect was remarkable.
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