Study On Biological Treatment Efficiency Of ASP Flooding Wastewater By Different Electron Acceptors

ASP flooding produced water usually contains a lot of alkali,surfactant and polymer.Therefore,traditional methods can not satisfiy the higher standards of oilfield reinjection water.In recent years,biological methods have reached better results in dealing with the complicated water.In order to get further effects on ASP flooding produced water by biological methods,we researched on five different electron acceptors: SO42-?SO32-?Fe2+ ?S2O32-?S0.The research based on sulfur cycle and microbiology.The research mainly applied three reactors.One of the reactors is anaerobic baffled reactor,when the electron acceptor is SO42-and SO32-.The hydraulic retention time was set as 72 h,carbon-sulfur ratio is 2:1,reflux ratio is 1:1.In the aerobic section,continuous aeration by aeration pump is adopted,and the air flow is 500 m L/min.The total runtime is 90 days,during which the change of the index of ternary water and the change of microorganism community structure in stable stage should be detected.The running temperature is 33-37? as SO42-as electron acceptor.When the reactor was in steady stage,the average total removal rate of COD,suspension,petroleum,polymer,surfactant and viscosity we got is respectively: 57.9%,64.0%,98.0%,37.5%,44.4%,and 38.9%.The running temperature is 10? as SO32-as electron acceptor.The average total removal rate of COD,suspension,petroleum,polymer,surfactant and viscosity we got is respectively: 68.4%,89.0%,98.8%,62.2%,39.6%,70.3% when the reactor was in steady stage.Another reactors is anaerobic baffled reactor,when the electron acceptor is Fe2+ and S2O32-.The hydraulic retention time was set as 48 h,carbonsulfur ratio is 2:1,reflux ratio is 1:1.In the aerobic section,continuous aeration by aeration pump is adopted,and the air flow is 500 m L/min.The total runtime is 90 days,during which the change of the index of ternary water and the change of microorganism community structure in stable stage should be detected.The running temperature is 33-37? as Fe2+ as electron acceptor.When the reactor was in steady stage,the average total removal rate of COD,suspension,petroleum,polymer,surfactant and viscosity we got is respectively: 41.2%,53.0%,98.6%,16.4%,45.4%,36.1%.The running temperature is 10 ? as SO32-as electron acceptor.The average total removal rate of COD,suspension,petroleum,polymer,surfactant and viscosity we got is respectively: 42.2%,64.0%,97.9%,18.2%,37.0%,24.0% when the reactor was in steady stage.Last reactor is A2/O craft when the electron acceptor is S0.The hydraulic retention time was set as 72 h,carbon-sulfur ratio is 2:1,reflux ratio is 1:1.In the aerobic section,continuous aeration by aeration pump is adopted,and the air flow is 500 m L/min.The total runtime is 90 days,during which the change of the index of ternary water should be detected.The running temperature is 10? as S0 as electron acceptor.When the reactor was in steady stage,the average total removal rate of COD,suspension,petroleum,polymer,surfactant and viscosity we got is respectively: 38.1%,64.0%,95.7%,17.9%,36.0%,40.0%.In conclusion,all the crafts with different electron acceptors can reach the standard of oilfield reinjection water but the effect is better when the electron acceptor is SO32-.When the crafts with different electron acceptors got into stabilization stage,The composition of microbial communities is different,but they have the same dominant bacterial community : the phylum of proteobacteria.When taking SO42-and SO32-as electron receptors,the anaerobic section in the reactor has the highest species richness and evenness.The phylum of proteobacteria is increasing and the removal rate of suspended matter,polymer and viscosity is greatly improved under this condition.Taking Fe2+ and S2O32-as electron receptors can promote the growth and propagation of microorganisms in the proteobacteria phylum of the aerobic section,thus improving the removal rate of pollutants from the aerobic section in water.