| Membrane bioreactor(MBR) is an efficient wastewater treatment process. Little activated sludge production ease the pressure of the subsequent treatment. Controlling HRT and SRT can raise sewage disposal efficiency. Simple operating conditions make it convenient for renovation and expansion project of se wage treatment plant. Unfortunately, MBR system has poor efficient in TN and TP removal. Meanwhile membrane fouling restricts the development of MBR. Microalgae which has short life cycle and full photosynthesis has a strong absorption effect on nitrogen, phosphorus, difficult dissolved organic matter and metal elements in the wastewater. But microalgae is easy to drain and difficult to recycle.In this study, microalgae was inoculated into MBR to combine the advantages of microalgae and membrane bioreactor. And concequently high removal effect of nitrogen and phosphorus as well as ecological treatment of sewage was achieved. The operation stability of microalgae- membrane bioreactor(A-MBR) was studied. Compared with traditional sludge MBR(S-MBR), the treatment efficiency of organic pollutants, nitrogen and phosphorus of A-MBR were investigated. The properties of the mixture were analyzed, and the membrane fouling were recorded.It was found that the slud ge concentration was fluctuating in 3000mg/L. By detecting the changes of MLSS, VSS and chlorophyll a in the A-MBR to estimate the growth of microalgae in sludge mixture. The concentration of chlorophyll a was stable at 2.1 g/L which proved the good condition of microalgae. Meanwhile, VSS was increased steadily, which showed that the sludge mixture had good biological activity. To sum up, A-MBR system was running stablly.Utilizing the traditional S-MBR as a control, the effect of A-MBR on the treatment of pollutants in water was studied. And the treatment efficiency was 96.52%. The removal efficiency of N H4+-N was 95.71%, while S-MBR was only 88.10%. The average removal rate of TN was 21.48% in A-MBR system during the 40 days, 11.15% more than S-MBR. And the treatment efficiency of TP was 11.15% higher than that of S-MBR.Under the constant flux of 8 L·m-2·h-1, the membrane fouling characteristics of the two sets of reactor were studied. The membrane fouling cycle of A-MBR was 146% longer than that of traditional S-MBR. And the average growth rate of TMP was decreased by 54%. By analyzing the content of SMP and EPS in two sets of systems, It was observed that EPS in A-MBR system was decreased, and the protein content of TB-EPS was also decreased. It is speculated that the decrease of TB-protein slowed down the membrane fouling. The sludge mixture in A-MBR system had better dewatering property and lower viscosity.Compared with the traditional MBR, microalgae-MBR system has better treatment efficiency for nitro gen and phosphorus. The dewatering and settling property of the sludge mixture were improved, the viscosity of the sludge was decreased, and the membrane fouling was effectively controlled. |
