Remediation Of Diesel Oil Pollution In Water By Immobilized Acinetobacter Venetianus And Heterogeneous Fenton-like Treatment

In this study,diesel oil was selected as a representative of petroleum pollution.The Acinetobacter venetianus shows high performance in degrading diesel oil was isolated from oil refining wastewater plant,in Fujian,China.When the initial concentration of diesel oil is 50.0 mg L-1,the growth curve of Acinetobacter venetianus could be well described by logistic equation(R2=0.92).When the initial concentration of diesel oil is 100 mg L-1,after biological treatment for 96 h,the removal efficiency reached to 80.5%,while the biodegradation process could be well fitted by first-order kinetics when the initial concentration of diesel oil ranged from 50-200 mg L-1.Scanning electron microscopy(SEM)demonstrated that the cells growed healthily in the aqueous contained diesel oil.Fourier transform infrared analysis(FT-IR)and Gas Chromatography Mass Spectrum(GC-MS)showed that the metabolites such as carboxylic acids,ketone,alcohols formed during the biodegradation process.The biodegradation of diesel in wastewater by Acinetobacter venetianus immobilized on bamboo charcoal was also investigated.The results showed that biodegradation efficiency was significantly improved using cells immobilized on bamboo charcoal compared to that of free cells,increasing from 80.50%(free cells)to 86.35%(immobilized cells)in 96 hours.To understand the biodegradation mechanism of diesel by Acinetobacter venetianus immobilized on bamboo charcoal,kinetics studies showed that biodegradation of diesel fitted well to the pseudo-second kinetic model(R2>0.999),indicating the diesel oil was firstly adsorbed onto bamboo charcoal and then degraded by immobilized cells.To further confirm it,SEM showed that Acinetobacter venetianus were immobilized well on modified bamboo charcoal,FTIR demonstrated the new bands were formed at 1497.4cm-1,1448.2cm-1,1381.8cm-1,1297.9cm-1,confirming degraded products such as esters and carboxylic existed.GC-MS analysis indicated that the removal of diesel oil was enhanced by immobilized cells compared to free cells.In summary,modified bamboo charcoal not only served as a carrier for bacterial,but also could be an absorbent for diesel oil,leading to enhance the degradation efficiency,which provides a new insight into the remediation of diesel oil in oil-contaminated site by biomaterials.When the initial concentration of diesel oil is 100 mg L-1,after the biodegradation lasted for 96 h.the removal of total organic carbon(TOC)and chemical oxygen demand(COD)is 57.2%and 62.3%,respectively.Which demonstrated that diesel oil can be the carbon sources for Acinetobacter venetianus,but there still exist lots of metabolites which were produced by the microbe.In order to further mineralized the diesel oil,after 24 h of biological treatment,Fenton-like oxidation technology was introduced.after the process of optimizing factors,it was found that when the addition of nanoscale zero valent iron(nZVI)is 1.5 g L-1,the dosage of H2O2 is 10 mmol L-1,pH=3.0,temperature is 298 k,the removal of TOC and COD in the aqueous could be as high as 86.3%and 89.6%,respectively.