| Submerged membrane bioreactor (SMBR) has many advantages than the traditional wastewater treatment technology, but the membrane fouling during filtrating operations prevents its wider application. At the same time, MBR usually use the lager gas-water ratio to relive membrane fouling, which also caused the absence of anaerobic and anoxic area, then leading to a low TN removal. In order to overcome this shortage, and decrease the power consumption of the SMBR, the characteristic and the treatment efficiency of wastewater treatment by the membrane aeration/filtration alternate membrane bioreactor (AMBR) were investigated in this paper. Based on the optimization of operation state, the removal effect of organics and nitrogen and the efficiency of membrane fouling control were also studied.As the current commonly membranes used for membrane aeration were hydrophobic microporous, which have the disadvantages of lower bubble point and limited oxygen supply. Combined with the requirement of membrane during sludge/water separation, the pretreatment method was carried out to improve the selected hydrophobic microporous membrane's oxygen supply efficiency and water filtration performance. The results showed that the adsorption method was effective for enhance the membrane's hydrophilic property when use the ethanol as hydrophilic agent, and the membrane after pretreatment was suitable for aeration and separation. The hydrophilic property of membrane was improved to a relatively higher degree when the pretreatment time reached to 5min, but there was no more obviously effect when the pretreatment time was more than 5min. Membrane aeration in clean water showed that the bubble point pressure increased from 1.5kPa of virgin membrane to 107kPa for membrane after 5min pretreatment, and its oxygenating capacity reached to 16.4g/m2·h, which was 6 times of virgin membrane, and the water filtration performance was also improved after pretreatment. The trans-membrane pressure (TMP) was only 12kPa when the membrane flux was 50L/m2·h, but the virgin membrane was no effluent when the TMP was 78kPa.Based on the selected membrane, the factors influencing the membrane aeration was studied in order to provide the basic parameters for membrane aeration applied to water oxygenation, biological treatment process and AMBR. The results showed that, the intra-membrane pressure, hydraulics and water quality had a significantly effect on the aeration which was merely affected by the membrane module's submerged depth. When the intra-membrane pressure was lower than the bubble point, the oxygen transfer rate and the capacity of oxygenation increased with the raise of intra-membrane pressure. The hydraulic condition also influenced the membrane aeration efficiency, and the capacity of oxygenation increased with the raise of the flow velocity at the surface of the membrane fiber. The deterioration of water quality would lead to the decrease of oxygen transfer rate and saturated the dissolved oxygen. However, when the submerged depth scale of the membrane model is between 10~40cm, the depth of the water had no effect on the membrane aeration.Based on the AMBR, the operating condition was optimized and the operating result affected by the DO of the bulk liquid, the C/N of the influent and alternate cycle of the reactor were all been investigated and the removal loading of the pollutant by the AMBR was also been studied. The results showed that, when the DO of the bulk liquid was 0.5mg/L, the AMBR had a good effect on simultaneous removal of COD, NH3-N and TN, which reached to 94.5%,96% and 78.4%, respectively. When the C/N ratio was between 3~10, the AMBR could remove the COD and NH3-N efficiently. However, the increase of the C/N was beneficial for the removal of the TN. The optimized result of alternate cycle of the membrane module showed that when the alternate cycle was 0.75~3h, AMBR relieve the membrane fouling effectively. The optimal alternate cycle was 3h because the longer alternate cycle was beneficial for reducing the lose rate of the aeration. Under the premise of the intra-membrane pressure being 200kPa, The removal loading of COD, NH3-N and TN by AMBR reached to 84.9, 6.6 and 6.5g/m2·d, respectively.The long-term operation of AMBR results showed that, the process had a stable and good effect on simultaneous removal of organic carbon and nitrogen. During the 120-day continuous operation, the COD, NH3-N, TN and SS removal efficiency by AMBR was more than 97%, 90%, 75%and 99%, respectively. The study in contrasts of AMBR and the traditional SMBR showed that, both MBR had a good performance on the removal of COD and NH3-N. However, the TN removal efficiency by the AMBR was better. The pilot scale study of domestic sewage treatment by the AMBR showed that, under the condition of the lower C/N ration (4) in influent, the TN removal efficiency was limited. However, when the C/N ratio increased to 6 by adding glucose into the influent, and the TN reduced to 15mg/L ,which can reach to met the First A-level requirement of《Pollutant Emission Standards of Municipal Sewage Treatment Plant》(GB18918-2002).The study of membrane fouling control by AMBR showed that, the AMBR had a better effect on membrane fouling control compared with the traditional SMBR. While the lower MLSS concentration, the viscosity of the bulk liquid, the EPS of the sludge and the backwash led the AMBR to be good at membrane fouling control. During the continuous 50-day operation, the TMP was always keeping around the -10~-15kPa; while the TMP in SMBR exceeded -30kPa and needed chemical cleaning after 27th day operation. After the continuous 120-day operation, the TMP of the AMBR membrane model didn't changed sharply. Compared with the new membrane model, the oxygenation and effluent performance also didn't have a marked change by the membrane model after long-term operation. The oxygenation efficiency of the AMBR is higher than 70%, as a case of the simulation of domestic sewage used in this test, the oxygen consumption was 0.285yuan/t.
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