Experimental Study On Fermentation Of Nutrient Solution To Induce Petroleum Bacteria To Promote Bioremediation Of Petroleum Contaminated Soil

This study changed the experimental conditions by bio-stimulation to explore the essence of the degradation of petroleum pollutants,and the relationship between nutrient and hydrocarbon degraders.The effects of the method of adding nutrient on the bioremediation of petroleum-contaminated soil were studied.The stimulating ability of nutrient to exogenous hydrocarbon degraders and the remediation efficiency of total petroleum hydrocarbons(TPH)were studied by combining bio-enhancement and biostimulation.The effect of small molecule organic carbon source(glucose and acetic acid),a microbial-dependent nutrient source,promoting and stimulating microbial growth by changing the carbon source ratio of glucose and acetic acid was explored.The research results are as follows:(1)Compared with the previous study,under the test conditions of extended reaction time(3m L of nutrient dosage),the TPH degradation efficiency of soil S2 increased by 16.1% while the corresponding efficiency increased by 20.7% under the test conditions of prolonging the reaction time(100 d)and increasing the nutrient amount.It can be seen that increasing the nutrient content and prolonging the reaction time can enhance the bioremediation efficiency of TPH.(2)At 100 d,the CO2 production of soil S1 and S2 systems was up to 1.34 mol/kg and 1.30 mol/kg respectively,indicating that the nutrient provides a large number of microorganisms with highly active for bioremediation compared with chemical conditions.(3)Nutrient can stimulate indigenous hydrocarbon degraders to rapidly propagate.The selection of hydrocarbon degraders to carbon source was divided into two stages.In the first stage,DOC was the dominant carbon source,and the hydrocarbon degraders was in the exponential growth stage.In the second stage,the long-chain alkanes were the dominant carbon source,and the growth of hydrocarbon degraders was slowing down.The change of hydrocarbon degraders selecting carbon source in these two stages is the mechanism of nutrient stimulating the growth of hydrocarbon degraders to degrade longchain alkanes.(4)The selection of microbe to carbon source was changed due to the sufficient external nutrition of intermittent external feeding method.Compared with the singleadding method,the advantage of bioremediation by intermittently adding nutrient was not very significant according to the perspective of microbial activity and TPH remediation efficiency.(5)In the 60-day bioremediation,the amount of exogenous hydrocarbon degraders added and the degradation efficiency of TPH have a linear positive correlation.Under the high exogenous bacterial amount with nutrient added,the degradation efficiency of TPH was 59% and 57% in soil S1 and S3,higher than 12% and 15% of the non-bacterial group respectively.These results indicated that exogenous hydrocarbon degraders can further promote the bioremediation of oil-contaminated soil,and the remediation ability of exogenous bacteria is mainly reflected in the initial stage of bioremediation.(6)The addition of small molecular carbon sources such as glucose and acetic acid can promote the degradation of TPH.Meanwhile,it was found that the higher the proportion of glucose components,the higher the degradation of TPH.The small molecular carbon source plays a certain role in promoting the degradation of long-chain alkanes.The highest degradation efficiency of long-chain alkanes in soil S1 and S3 were 47.7% and 38.3% respectively.