无泡充氧膜生物反应器对生活污水处理效果的研究

Effect of Non-bubble Aerated Membrane Bioreactor on Domestic Wastewater Treatment

针对低碳氮比的实际生活污水,设计了一种以疏水性微孔膜作为无泡充氧和生物膜载体的膜生物反应器,研究了水力停留时间(HRT)、充氧方式、水温对反应器处理效果的影响,并探究碳、氮元素的转化途径。结果表明,在HRT为24 h、水流速度为0.068 m/s、水温为28~36℃、DO为(1.6±0.2)mg/L、充氧强度为0.035 MPa条件下,系统对COD、NH4^+-N和总氮的平均去除率可分别达到85.43%、72.22%、57.95%。在碳、氮元素的转化途径上,污水在通过由无泡充氧形成的生物膜的不同氧浓度梯度分层结构后,可进行同步硝化反硝化,对氨氮的去除主要依靠硝化菌完成,去除率为72.18%,对TN的去除率约为56%,而在反硝化过程中COD主要作为碳源被大量消耗,平均去除率达到85%以上。反应器主要耗能为空压机、循环泵和进水隔膜泵的电耗,无泡充氧的氧体积传质系数约为传统鼓泡式充氧的8.7倍,节约充氧电耗的潜能可达88.5%。

A membrane bioreactor with hydrophobic microporous membrane as the carrier of nonbubble aeration and biofilm was designed and developed,and it was applied to treat the actual domestic wastewater with low carbon and nitrogen ratio.The influence of hydraulic residence time(HRT),aeration mode and water temperature on the treatment efficiency of the reactor was studied,and the transformation pathways of carbon and nitrogen elements were explored.The average removal efficiencies of COD,NH4^+-N and total nitrogen reached 85.43%,72.22%and 57.95%when HRT was 24 h,flow velocity was 0.068 m/s,water temperature was 28-36℃,DO was(1.6±0.2)mg/L and aeration intensity was 0.035 MPa.During the transformation of carbon and nitrogen,simultaneous nitrification and denitrification took place when sewage passed through biofilm with different oxygen concentration gradients formed by non-bubble aeration.The removal of NH4^+-N was mainly completed by nitrifying bacteria,and the removal rate was 72.18%.Meanwhile,the removal efficiency of TN was approximately56%.During the denitrification process,COD was mainly consumed as a carbon source and its removal efficiency was more than 85%.The main energy consumption of the reactor was air compressor power consumption,circulating pump power consumption and intake diaphragm pump power consumption.The oxygen mass transfer coefficient of non-bubble aeration was 8.7 times of that of traditional bubble aeration,and the potential energy consumption of non-bubble aeration could be saved up to 88.5%.