Study On The Technology Of Remedying Marine Oil Pollution By Immobilized Petroleum-degrading Bacteria

In recent years,marine oil pollution is becoming more and more serious,so the highly efficient remediation technology has been a research hotspot.The immobilized bacteria is used to remediate petroleum-polluted seawater in situ,does not produce secondary pollution and get favorable result in protecting marine ecological environment.But so far,it is key how to improve the effect of immobilized bacteria remediating marine petroleum-polluted environment.In this paper,bacteria were immobilized by adsorption method.Diesel was used be the reaction substrate.Firstly,the diesel degradation effects of bacteria immobilized on different carriers were compared.Then,the microbial activity,total nitrogen and total phosphorus in the process of diesel degradation were analysed,and the synergistic degradation mechanism of petroleum-degrading bacteria and carriers were preliminarily studied.Third,the immobilization conditions were optimized.Finally,the community structure changes of the immobilized bacteria with the degradation time were studied.Experiments aimed at exploring the effects of petroleum-degrading bacteria immobilized on different carriers.The results showed that organic material-straw was the best immobilized carrier.The diesel degradation rates were ranked as follows:corn straw>wood chip>corn leave>corn cob>peanut shell.The diesel degradation rate of petroleum-degrading bacteria immobilized on straw was highest 75%in 20 days.The microbial activity of petroleum-degrading bacteria immobilized on wood chips and corn straws were higher than others.In the meantime,the dehydrogenase amount of bacteria immobilized on corn straws was to 4.01 ?g/mL on 5th day,which indicates that the effect of corn straw is the best immobilized carrier.On this basis,corn straw was used as an immobilized carrier,and the single factor experiment was used to optimize the immobilization conditions.Based on the single factor method,response surface methodology was used to analyze the effects of individual factors on the immobilization.With biomass and enzyme activity as the response values,the results showed that the initial dosage of degrading bacteria and the time of immobilization had a greater influence.The optimal immobilization conditions were obtained:pH value of 7.25,immobilization time of 3.5 days,degrading bacteria dosage of 5.35×107cfu/mL,and carrier particle size of 3mm.Then,immersing the corn straw in the water found that the amount of nitrogen released from the carrier increased from 6.95 mg/g to 16.92 mg/g in 4-16 days,and the phosphorus release increased from 0.0708 mg/g to 0.232 mg/g.In addition,the release rate of nitrogen was the largest in 2-4 days,and the largest release rate of phosphorus was 4-7 days.And it was found that the compositions of the microbial community were changed during the process of degrading diesel by immobilized petroleum-degrading bacteria,due to the selectivity of diesel to the dominant bacteria.That is,the amount of Stenotrophomonas sp.and Alcanivorax sp.were increased,and the amount of Achromobacter sp.and Pseudomonas sp.were decreased.The degradation effect of immobilized petroleum-degrading bacteria is obviously better than free bacteria.In this paper,different organic materials as immobilized carrier were compared which provides the basis for the application of immobilized bacteria to petroleum-polluted marine.