Study On Fast Start-up Of ASP Flooding Wastewater BESI Technique Based On Sulfur Electron Acceptor

The application of ASP flooding technology has produced a large amount of ASP produced water as well as ensuring high and stable production of crude oil in Daqing oilfield.The ASP flooding wastewater is complex and the water quality is special.The traditional methods of oilfield wastewater treatment are difficult to meet the standard and the treatment cost is higher.Previous study found that biological method was good for the treatment of ASP flooding wastewater,but the effect was not stable.Studying the method of strengthening reactor operation and exploring the fast start-up of the reactor are of great significance for the practical application of BESI technique.In this paper,the effects of different sulfur electron acceptors on the treatment of BESI process and the fast start-up of ABR like reactor were studied.In this paper,the effects of SO42-and SO32-used as electron acceptors on the performance of BESI process were studied and the change of community structure of sludge in different reactors was analyzed.The operating conditions were as follows: HRT 48 h,the reflux ratio 1:1,C/S 5:1 and temperature 33?.In the stable operation period,with SO42-as electron acceptor,the average removal rates of COD,suspended solids,oil content,HPAM,viscosity and surfactant were 34.1%,94.6%,98%,10%,34%,25.0% and with SO32-as electron acceptor,the average removal rates were 48.3%,96.1% 99%,14.4%,39.8%,30.5% which was better in BESI process effluent.The effluent can meet the reinjection standard of oilfield containing polymer.Biological community structure of different reactor sludge in BESI process was different and the difference of biological community structure in the same reactor sludge was large when different sulfur electron acceptor was used.The main functional microorganisms belongs to the Halomonas group and their ability to remove pollutants is stronger in BESI process.When SO42-was used as electron acceptor,the species evenness was higher in sludge and the species richness in anaerobic sludge and facultative sludge also was higher.When SO32-was used as electron acceptor,the species richness of aerobic sludge increased and it promoted the growth and reproduction of Halomonas microorganisms,which resulted in lower species evenness and species diversity in BESI process.In the study of the fast start-up of a ABR reactor,fast start-up was achieved with a small amount of activated sludge by means of sulfate intensification and the use of fillers through 46 d.In the stable operation period,the average removal rates of COD,HPAM,viscosity,surface active agent were 29.3%,17.5%,35.6%,21.3% in the effluent.The oil content is less than 5 mg/L in effluent,which can meet the reinjection standard of oilfield containing polymer.But the suspended solids content was more than 22 mg/L in effluent which needs to be filtered before reinjection.By the analysis of microbial community structure in activated sludge collected at the end of start-up and stable operation,there was a big difference between different periods of sludge samples and species richness and species diversity of sludge collected in stable operation was higher.Halomonas was the main functional microorganisms in the ABR like reactor and the reduction of sulfur content in water was the major cause of the decrease in the specific gravity of the sludge.