An Experimental Research On Treatment Of Domestic Wastewater By Anaerobic Membrane Bioreactor With Constructed Wetland

The indiscriminate discharge of the rural decentralized domestic wastewater in our country has begun to destroy the ecological environmental in rural areas.The cost of the existing technologies for treating and disposing decentralized domestic wastewater is beyond the economic capacity of vast rural areas.This study is based on the treatment of decentralized domestic wastewater.To build a laboratory scale anaerobic membrane bioreactor?AnMBR?and treat the actual campus domestic sewage as the experimental object.We can play low-load,low-cost,long-term effective operation advantages.With the constructed wetland technology as a follow-up treatment process,we will achieve the local treatment and reuse of the decentralized domestic wastewater and provide the referenced thought and supportive technology for the domestic wastewater treatment of vast rural areas in our country.The Lab-scale external immersed AnMBR with the total effective volume of 9.5 L treated the campus domestic sewage continuously-running has achieved the optimal HRT of 12 hours with the Flux of 3.6 L/?m2·h?under ambient temperature?18³7??.The removal rate of TCOD was 90.6±2.4%and the TCOD value of the effluent was stable below 50 mg/L for up to 117 days.The NH₃-N could hardly be removed under anaerobic conditions,but the TN concentration value in effluent was 5 mg/L lower than that of the influent.45 days since AnMBR stared running the effluent TP concentration was significantly lower than that of the influent and the reactor maintained a certain removal rate.The MLSS and MLVSS value were respectively 8.7 and 5.8 g/L during the stable operation period,then the concentration of both varied respectively between 5.0⁷.5 and3.6⁵.5 g/L during adaptive adjustment period.MLVSS/MLSS value increased from 0.67to 0.73 which meant the microbial activity of the anaerobic microorganisms in AnMBR has always been high.Upward vertical flow constructed wetland with 72 L effective volume was used to remove the nitrogen and phosphorus pollutants in the AnMBR effluent.The optimal HRT was 10 days with the zeolite and shale granules as the substrate materials under ambient temperature?13¹6??.The average removal rate of COD,NH₃-N,TN,TP were respectively 77.6%,37.7%,36.8%,7.1%during optimized operation period.However the adsorption capacity of the substrate materials was close to saturation after 90 days since treating AnMBR effluent.There was no significant change in COD Removal after covering soil layer,but the removal rate of NH₃-N and TN was 49.6%and 34.4%.The removal effect of TP was the best and the TP concentration of constructed wetland effluent was below detectable limit among 70 days,the removal rate of TP was once achieved 100%and reduced to 69.2%in the later period.It got a better effect of soil purification and the hygrophyte Iris pseudacorus L grew well which made the plant have landscape value.Membrane fouling was comprehensively affected by the influent water Quality,HRT,VLR and temperature.When extended AnMBR HRT to 24 hours and kept it in the way of intermittent operation which peristaltic pump ran 8 minutes stopped 2 minutes,the TMP value increased from 0.3 kpa to 19.6 kpa in 108 days which meant that the membrane in the AnMBR achieved the goal of long-term effective operation.According to the results of this study and relevant design criterion,it was to take 100 t/d of treatment scale as an example to develop a set of product and process.The analytic results showed that it could cut down 14.6 t COD while provide 12.2 t nitrogen fertilizer and 1.2 t phosphorus fertilizer when treated rural domestic wastewater which could create significant economic benefits.