Study On Methane Cycle Anaerobic Membrane Bioreactor For Treating High Salt Wastewater

Nowadays,many production fields produce high salt organic wastewater with the development of industrialization in China.However,it's very difficult to solve the problem about how to treat the high salt organic wastewater.Therefore,domestic and international experts in this field are devoting to explore the biological method which is high salinity tolerated.There are two kind of the most common wastewater of high salt wastewater: the high chlorine salt wastewater and the high sulfate wastewater,which are mainly from seawater desalination,printing and dyeing,paper making,pharmacy,seafood,dairy products processing,chemical,pesticide and so on.In this topic,the Methane Cycle Anaerobic Membrane Bioreactor?MCAnMBR?researched by ourselves is used to do the pilot-scale experiment on these two kinds of wastewater which contain a concentration of Cl-and SO₄^2-as high as 9000mg/L.Before the experiment,we will probe the feasibility of using the MCAnMBR to treat the wastewater,after that,tolerance values and process operation parameters of MCAnMBR will be explored.Meanwhile,the sludge particle size,microbial morphology,particle size of anaerobic gas production and anaerobic gas composition will be measured at the stage of stable operation.We realize the membrane fouling process through record the differential pressure across the membrane during the whole experiment.Using MCAnMBR to treat these two kind of wastewater is viable.There is no obviously inhibitory effect for the reactor,When the temperature between 22.6 ? and26.5 ?,the influent concentration of COD between 24650mg/L and 34720mg/L,the influent concentration of NaCl reaches 16.72g/L,the volume loading from4.9kgCOD/?m³· d?to 6.9kgCOD/?m³·d?,the HRT up to 120 h and the MLSS resches 25g/L.In the meantime,when the influent concentration of COD less than 2000mg/L and the total removal rate of COD between 94.25% and 99.61%,the VFA in the reactor will less than100mg/L.The high chlorine salt influent contains a concentration of NaCl from 19g/L to 20g/L can be treated by the domestic MCAnMBR;The effects of stable operation process of the reactor are: temperature,from 20? to 26?.The influent concentration of COD,between1648.9mg/L and 23764.8mg/L;The influent concentration of NaCl,from 19g/L to 20g/L;The HRT,up to 20h;The organic loading rate?OLR?,reaches 4.5 kgCOD/?m³·d?and the MLSS,resches 27g/L.The removal effects of COD by MCAnMBR is excellent when thereactor in a stable operation environment.In this environment,the total removal rate of COD between 84.58% and 90.44%,the pH of the reactor from 7.61 to 7.85,the alkalinity between 1251mg/L and 1511mg/L,the VFA from 260.68mg/L to 410.57mg/L and MLVSS/MLSS is 0.6572.Using MCAnMBR to treat the high sulfate wastewater is doable.The high Na2SO4 inflow can be treated when it's concentration meet the following criteria: The concentration of COD between 18000mg/L and 21000mg/L;The concentration of SO₄^2-from 9082mg/L and 9600mg/L and the COD/SO₄^2-meet 2.The effects of stable operation process of the reactor are: Temperature,from 23.3? to 25.4?;The HRT,up to 120h;The MLSS,reaches 17.24g/L;The OLR,between 3.68kgCOD/?m³·d?and4.36kgCOD/?m³·d?;The operation result of the reactor is good;The effluent concentration of COD,between 650.83mg/L and 976.56mg/L;The total removal rate of COD meet95.36%⁹7.9%;The reduction percentage of SO₄^2-up to 49.76%;The VFA in the reactor,from 300.181mg/L to 706.63mg/L;The alkalinity,between 2172.17mg/L and3379.21mg/L,The pH from 7.18 to 7.61 and MLVSS/MLSS is 0.6429.In an environment of high chlorine salt,the diameter of the sludge is between 6 and76 microns and in an environment of high sulfate,the diameter of the sludge is between 4and 34 microns.When the high sodium chloride simulated wastewater treated by MCAnMBR,the microbial flocs surrounded by a large number of bacillus and less free micrococcus will be relatively tight.On the contrary,when the high sodium sulfate simulated wastewater treated by MCAnMBR,the microbial flocs mainly surrounded by micrococcus and no bacillus will be relatively loose.In general,the reactor combine methane cycle and water stir together,will has more advantages than other reactors,the sludge in it will be looser and transmit more quickly.The detection of transmembrane pressure?TPM?improves that MCAnMBR can run longer time than other kind AnMBR.The whole membrane fouling process can be divided into three phases.First,the rapid growth of the TPM in the short term.Second,slow and steady growth for the long term.Lastly,rapid growth for the short term.During the whole experiment,the membrane contribution is between 0% and 30%,the average percentage is5.9%,this phenomenon can improve the sewage treatment capacity of MCAnMBR effectively and can improve the stability of the effluent quality.The membrane separation rate is between 0% and 93%,the average percentage is 35.41%.Temperature rise is helpful for membrane separation of pollutants,when the temperature up to 28?,the membrane separation rate will reaches 90%.