| Oily sludge,is the material which has a complex composition,large size,a great harm to the human health and the natural environment,its safe disposal has been attracting a lot of attention.At present,the treatment of oily sludge is mainly including physical and chemistry methods and biological methods: physical and chemistry methods,are including chemical oxidation,incineration,etc,and their disadvantages are that they are expensive and ineffective;biological treatment methods are including plant repair,microbial repair,etc,and their advantages are that they have a relatively low cost and their treatment effect are relatively good,but each kind of biological treatments also has its own shortcoming,such as plant repair has a long cycle,the process is slow,and it can only remove the oil where the root of plant can extend;microbial remediation techniques have the disadvantage of poor adaptability of exogenous bacteria to specific oily sludge.In this study,the oily soil near Shaanxi Yanchang Petroleum?Group?Co.,Ltd.was used as the source of the strain,and petroleum-degrading bacteria were screened.On this basis of that,plant-microbe associated bioremediation was used to treat the oily sludge,and the effect of enhanced bioremediation were comprehensive analysed.The results are as follows:?1?Three petroleum-degrading bacteria were obtained by enrichment and sep aration.They were identified by 16 S rDNA,which were Chryseomicrobium sp.Y L2?Flavobacterium?,Gordonia sp.YL3?Gordonella?,Acinetobacter sp.YL5?Acine tobacter?.?2?Petroleum-degrading bacteria characteristics of the three strains were studied.The results are as follows:For the three petroleum-degrading bacteria,the oil degradation rates were 86%,81% and 97% at the petroleum concentration of 2 g·L-1,respectively.When the oil concentration was 8 g·L-1,the oil degradation rates were 37%,56%,42%.As a result,the degradation rate of petroleum-degrading bacteria decreases with the increasing oil concentration.For the three petroleum-degrading bacteria,the degradation rate of petroleum was 41%,39% and 44% at the initial pH value of 5,respectively.When the pH value was 7,the degradation rates were 69%,74% and 64%.At pH 8.5,the oil degradation rates were 38%,36%,41%,respectively.Therefore,the three oil degrading bacteria at pH is 7,the highest degradation rate,In addition to that,the oil degradation rate has decreased.?3?By means of plant-microbe associated bioremediation of oily sludge,the degradation rate of total petroleum hydrocarbons was 66.10%,30.49% higher than that of natural remedies,and were higher than phytoremediation?54.20%?and microbial remediation?61.65%?,respectively.Plants or microorganisms are selective for the degradation of the total petroleum hydrocarbon component: the plant or the microorganism has a better degradation efficiency for the shorter carbon chain component?C11-C15?,either alone or in combination;but the degradation efficiency of the longer carbon chain?C26-C29?is relatively low,either alone or in combination;for medium-length components?C16-C25?,plant-microbial remediation is superior to plants or micro-organisms alone,indicating that there is a certain interaction between plants and microorganisms to promote the degradation of petroleum hydrocarbons.?4?During the plant-microbe associated bioremediation process,the total number of microorganisms reached 5.82E+7cfu·g-1,which was 2.63 times that of microbial remediation(the total number of microorganisms was 2.21E+7cfu·g-1),which was 2.94 times that of phytoremediation(the total number of microorganisms was 1.98 E +7 cfu·g-1),indicating that plants and microbes have synergistic effects to increase the total number of microbes.?5?During the plant-microbe associated bioremediation process,the dehydrogenase activity reached as high as 198.48 ?g·g-1·h-1),which was 4.24 times that of natural remediation(46.8 ?g·g-1·h-1),which was higher than that of phytoremediation and microbiological repair,indicating that plant-microbial synergistic removal of total petroleum hydrocarbon,with a good repair effect.?6?The oil sludge by means of plant-microbe associated bioremediation,the biological toxicity is 2691 mg·kg-1,which is about one third of the initial value,which is lower than that of phytoremediation and microbial remediation,so plant-microbe associated bioremediation is an effectively treat the oil sludge method and it can be applied to the actual production. |
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