Effect Of Fermentation Carbon Source Prehydrolysis On Characteristics Of Rhamnolipids Produced By Strain Pseudomonas Aeruginosa NY3 And Application Of Rha In Oily Sludge Treatment

As an biosurfactant,Rhamnolipid is widely concerned and studied for its innocuity,high-performance,and non-pollution,it can be widely applied to the treatment of hydrophobic pollutants and other industries.Howerver,due to low output,high production and use cost and unstable technological conditions,the large-scale practical application is limited.At present,the research at home and abroad mainly focuses on improving the yield of Rha by screening fermentation carbon sources and optimizing fermentation conditions.However,little research has been done on the prehydrolysis of fermentation of carbon source to release the precursors for the synthesis of Rha..Based these situations,this paper would conduct a research which is of great significance for improving the yield of Rha,stabling fermentation process of Rha,and making preliminary attempt for its scale production and practical application.In this paper,Pseudomonas aeruginosa NY3,was used as tested strain,discarded animal oil was choosed as carbon source of fermentation,the effects of prehydrolysis of carbon source on the characteristics of Rha produced by Pseudomonas aeruginosa NY3and the optimization of prehydrolysis conditions were studied.The fermentation conditions of Rha produced by Pseudomonas aeruginosa NY3 which used prehydrolysised animal oil as carbon source were optimized.On this basis,Rha was used in the treatment of oily sludge in petrochemical enterprises.Obtain the following results:?1?The optimum conditions of hydrolysis of carbon source were obtained by using the acid value of prehydrolyzed waste animal oil to obtain the optimum conditions for hydrolysis of carbon source:alkaline prehydrolysis conditions were NaOH concentration 0.1 mol/L,hydrolysis for 12 h at 70?;enzymatic prehydrolysis conditions were lipase/PBS concentration 500mg/L,hydrolysis for 6 h at 50?.On this conditions,the largest acid value could respectively reached to 72.04 mg/g and 73.75mg/g,The content of free fatty acids in the hydrolysate is in the order of oleic acid>palmitic acid>stearic acid>linoleic acid>9-hexadecenoic acid>f tetradecoic acid>margaric acid.It was found that the prehydrolysis of carbon source did not affect the main components of Rha produced by NY3.However,afteralkaline prehydrolysis and enzymatic prehydrolysis,the proportion of mono-Rha was relatively high,the highest was 65.67%and 87.32%respectively.?2?When the waste animal oil was alkaline prehydrolysised or enzymatic prehydrolysised,Rha yield produced by NY3 and carbon source conversion rate could be enhanced,and Rha had good emulsifying properties.The optimum condition for NY3 producing Rha with prehydrolyzed carbon source was that the initial pH of the culture medium was 8.3,the nitrogen source was NH₄NO₃ and the total nitrogen was certain,the nitrogen source was added in three times,the yield of Rha could reach 18.75g/L,and the conversion rate of carbon source was 46.88%.When the inoculation,temperature and rocking bed speed were increased to 15.64%,32.93?,and 174.13r/min,the yield of Rha and the conversion rate of carbon source could be further increased to 19.75 g/L and 49.38%respectively.?3?When the above produced Rha was applied to the enlarged scale treatment of oily sludgeproduced by petrochemical enterprise,Rha could obviously improve the removal rate of alkane and aromatic hydrocarbon in the oily sludge.And when the content of di-Rha was high,the promoting effect was more obvious.The highest removal rate of pollutants can be increased by 30.83%.