Novel Anaerobic Biofilm Filter Reactor For Low-strength Wastewater Treatment At Low Temperature

The novel anaerobic biofilm filter reactor combines the advantages of dynamic membrane bioreactor?DMBR?and biofilm reactor.Similar to the structure of DMBR,the separation of liquid and solid is carried by the dynamic membrane which is adhere to the membrane module.Differ from DMBR,the pollutants in the novel reactor are removed by the dynamic membrane not the suspended activated sludge,because the dynamic membrane is not only a filter but also a biofilm rich in microbial.When wastewater in the novel reactor is through the dynamic membrane,pollutants degradation process and solid-liquid separation process are happened at the same time.The driving force of the effluent is hydraulic pressure,so the mass transfer efficiency is much higher than the tradition biofilm reactor,and the pollutants removal of the reactor has been improved.Moreover,result from that there is no suspended sludge in the reactor,the membrane fouling of the novel reactor has been greatly mitigated,and the reactor's operational stability has been further improved.The membrane module is made of nonwovens which is a kind of low-cost material.The pore size of nonwovens is much larger than the UF/MF,so it is unnecessary to use a pump for effluent.In addition,it is also unnecessary to provide disturbance to the reactor.So the energy consumption of the novel reactor has been greatly reduced.Only few of energy can be recovered when using anaerobic process for low-strength wastewater treatment,so the mesophilic anaerobic process can cause enormous loss of energy.In our study,we decided to operate the novel reactor at low temperature environment?18??.And that compered to suspended-grown biomass,the attached-grown biomass's adaptive capacity to environment is better,so it can adapt to the low temperature environment faster.At low temperature environment,the novel anaerobic biofilm filter reactor has operated continuously for 122 days.The HRT is 12 h and the effluent flux is 3.2 LMH.After the biomass adapted to the low-temperature environment,the COD removal of the novel reactor is stable over 80%.The filtration performance of the novel reactor has also been studied.The TMP of the novel reactor is increased rapidly for the first few days,and then become slower gradually.After the 122 days' operation,the TMP of the reactor is about 8 cm·H₂O.The reactor's operational stability is quite good.Additional,the turbidity of the effluent is below 1.5 NTU and the average VFA concentration in the effluent is 26.6 mg/L.The experimental data of the effect of HRT on the novel reactor indicate that there is no obviously effect on turbidity of the effluent,effluent turbidity of the both reactor?HRT:7.5 h,12 h?are below 1.8 NTU.Its effect on COD removal become obviously when the microorganism has adapted to the low temperature environment,the COD removal at this stages of the two reactors?HRT:7.5 h,12 h?is 72.8%and 77.4%,respectively.Additional,shorter HRT and larger flux lead to higher mass-transfer efficiency when wastewater through the biofilm.HRT have a great influence on filtration performance of the novel reactor,TMP of the two reactors?HRT:7.5 h,12 h?at day 100 is 9.9 and 16.6 cm·H₂O.Overall,the novel anaerobic biofilm filter reactor can basically be operated stability and efficient at low cost and low energy consumption,so it is a promising process for wastewater treatment.