Study On The Degradation Characteristics Of Oily Sludge By Surfactant Producing Bacteria

In the process of oil exploitation,transportation and smelting,it is difficult to deal with the"three mud".In order to solve this problem,the mainstream disposal methods include pyrolysis,extraction,solidification and biological methods.Among them,microbial degradation has become a new trend of oily sludge degradation due to its green,pollution-free,low cost and good effect.In this study,the biochemical sludge and scum produced in the process of refining wastewater treatment of Nanjing Jinling Petrochemical Company were used as degradation objects.A surfactant producing oil degrading strain was screened from the scum produced by Nanjing Jinling Petrochemical Company and the oily sludge near an oil factory in Daqing Oilfield,and the molecular identification of the selected strain was carried out.The fermentation products were identified by experiments,and the best fermentation conditions were determined to achieve the highest production of surfactant.Finally,the preparation conditions of immobilized bacteria were optimized to complete the preparation of bacteria.The main results are as follows.(1)Aiming at the problem of scum produced in the process of oil wastewater treatment in refinery,the oil in scum was separated by microwave radiation to realize the purpose of recovery.For scum with water content of 57.14%and oil content of 16.28%,the effects of slurry water ratio,power and time on the efficiency of microwave deoiling were investigated.When the ratio of mud to water is 3:4,the time is 4 minutes and the power is 280 W,the highest recovery rate of crude oil is 8.27%.(2)A strain GJ was isolated from oily sludge of Daqing Oilfield.It can not only secrete surfactant,but also has good removal effect on petroleum hydrocarbon.The external morphology of the strain was observed,the physical and chemical properties of the strain were analyzed,and the 16S rDNA sequence was determined.Finally,the strain GJ was identified as Shewanella The strain GJ was applied to the degradation experiment of scum and biochemical sludge,and the degradation kinetics of scum and biochemical sludge was discussed.The results of extraction and purification,TLC and IR showed that GJ produced glycolipid surfactants.In the experiment of scum and biochemical sludge degradation,the highest degradation rate of petroleum hydrocarbon was 81.11%and83.21%at the 7th day,respectively.Logistic growth model,luedeking piret model and first-order kinetic model can well simulate the growth of GJ,the synthesis of surface active products and the degradation of petroleum hydrocarbons.It is preliminarily inferred that GJ bacteria use petroleum hydrocarbon as carbon source.In the growth process,it secretes surfactant to break the oil-water interface,increase the contact degree between the strain and petroleum hydrocarbon,and promote GJ bacteria to absorb,metabolize and self proliferate petroleum hydrocarbon.(3)A surfactant producing petroleum hydrocarbon degrading bacterium named KMJ-1 was isolated from the biochemical sludge of Sinopec Nanjing Jinling Petrochemical refinery.KMJ-1 was identified as Alcaligenes sp.by morphological observation,physiological and biochemical experiments and 16S rDNA sequence analysis.After the composition of the product was characterized by experiments,the purified product was identified by comparing the results.KMJ-1 was applied to the degradation experiment of scum and biochemical sludge,and the degradation kinetics of KMJ-1 on scum and biochemical sludge was discussed.The degradation rate of petroleum hydrocarbon of strain KMJ-1 was 80.06%on the 7th day,and the degradation rate of petroleum hydrocarbon of strain KMJ-1 was 85.88%on the 7th day.Logistic model,luedeking piret model and first-order reaction model were used to build the cell growth kinetics model,surface active product synthesis kinetics model and petroleum hydrocarbon degradation kinetics model of KMJ-1.The three equations fit well and can well simulate the process of cell growth,product synthesis and petroleum hydrocarbon degradation.(4)In order to improve the biodegradation rate of oil degrading bacteria KMJ-1 and GJ,the culture conditions of the two strains were optimized by response surface methodology.Firstly,Plackett Burman experiment was used to determine the significant influencing factors of KMJ-1 culture process were N source and liquid volume,and the significant influencing factors of GJ culture process were c source and rotating speed.Then,the climbing experiment and CCD experiment were used to approximate the optimal conditions.The optimal culture conditions of KMJ-1 were obtained as follows:C source was 20 g,N source was 4.62g,Mg SO₄·7H₂O was 0.125 g,KH₂PO₄ was 1 g,rotating speed was 160r/min,and temperature was 25?The optimal culture conditions of GJ were as follows:C source was 26.94 g,N source was 10 g,Mg SO₄·7H₂O was 0.125 g,KH₂PO₄ was 1 g,rotation speed was 210.07 r/min,temperature was 25?,liquid loading was 50%,the surface tension was40.70 Mn/m,oil degradation rate was 84.45%,which was 3.34%higher than that before optimization.(5)Ophiopogon japonicus was used as carrier to prepare immobilized bacteria.The biochar made from Ophiopogon japonicus is hollow columnar and has a relatively complete deep pore structure,which is easier to absorb microorganisms and water,and increases the contact with oxygen,providing a good living environment for the strain.The results showed that the structure of Ophiopogon japonicus biochar was stable and the carrier adsorbed the bacteria and filled the space of the carrier.This study realized the recovery of oil from scum by microwave radiation,reduced the oil content of scum,provided an efficient energy-saving and environmental protection method for oily sludge treatment,and provided a theoretical reference for the study of the mechanism and engineering application of alkalobacillus degrading petroleum hydrocarbons.