厌氧膜生物反应器处理市政污水的产甲烷性能及微生物代谢特征

Study on Process Characteristics and Microorganism of Anaerobic Membrane Bioreactor for Municipal Wastewater Treatment

厌氧膜生物反应器(anaerobic membrane bioreactor,AnMBR)作为一种新型厌氧处理技术,可高效去除污水中的有机物并以CH4的形式回收再利用,降低污水处理能耗与碳排量,助力实现“双碳”目标.为评估AnMBR处理市政污水时的能源回收潜力,进一步揭示处理系统工艺特性,考察了不同水力停留时间(hydraulic retention time,HRT)下AnMBR处理市政污水的污染物去除及产甲烷性能、微生物代谢产物及微生物群落组成特征.结果表明:(1)在室温条件下,HRT从24 h缩短至3.2 h过程中反应器均可实现高效的化学需氧量(chemical oxygen demand,COD)去除与产甲烷性能,COD去除效率稳定在95%以上,进水77%以上的COD转化为CH_(4),出水COD浓度低至(21.2±7.8)mg/L.(2)反应器中溶解性微生物代谢产物(soluble microbial products,SMP)浓度为70~200 mg/L(以COD计),蛋白质/多糖(含量比,下同)为4.3~5.5,远高于胞外聚合物中的蛋白质/多糖(2.0~4.0),膜污染潜力高.(3)微生物群落分析发现,产甲烷古菌与细菌的丰度比与固体停留时间(solid retention time,SRT)呈显著负相关(P<0.05),且不同粒径颗粒中微生物群落组成差异显著,产甲烷古菌在粒径≥10μm的颗粒中丰度较高,维持混合液挥发性悬浮固体浓度(MLVSS)在8.0~11.5 g/L之间、SRT在60~80 d之间可避免功能菌群失衡.研究显示,AnMBR处理市政污水可实现良好的污染物去除效果与产甲烷性能,但过长的SRT会导致污泥浓度过高、SMP浓度增大以及产甲烷古菌丰度降低,影响反应器高效稳定运行.

Anaerobic membrane bioreactor(AnMBR),as a novel anaerobic treatment technology,can efficiently remove organics and recover CH4 in sewage treatment,reduce energy consumption and carbon emission,and help achieve‘carbon peak and neutrality’.To evaluate the energy recovery potential and reveal the process characteristics of AnMBR in the treatment of sewage,the organics removal efficiency,methane production efficiency,microbial metabolites,and characteristics of microbial community of AnMBR treated sewage were investigated under different hydraulic retention times(HRT).The results are as follows:(1)When the HRT was shortened from 24 h to 3.2 h,the reactor achieved high-efficiency chemical oxygen demand(COD)removal and methane production performance at room temperature.The COD removal efficiency was over 95%,and more than 77% of the influent COD was converted into CH_(4),resulting an low effluent COD concentration of(21.2±7.8)mg/L.(2)The concentration of soluble microbial products(SMP)in the reactor was 70-200 mg/L(calculated by COD);the protein/polysaccharide(content ratio)of soluble microbial products was 4.3-5.5,which was much higher than that of extracellular polymeric substances(2.0-4.0),indicating that the soluble microbial products had a high membrane fouling potential.(3)Microbial community analysis showed that the abundance ratio of methane producing archaea to bacteria was significantly negatively correlated with solids residence time(P<0.05),and microbial community with different particle sizes showed large difference,and methane producing archaea reached higher abundance in particle size≥10μm.Maintaining an appropriate volatile suspended solids concentration of 8.0-11.5 g/L and SRT of 60-80 days was beneficial to avoid the imbalance between bacteria and methane producing archaea.The results show the AnMBR can achieve excellent pollutants removal efficiency and methane producing performance in sewage treatment,while overlong SRT may result in high sludge concentration,increase of soluble microbial products concentration and decrease of methane producing archaea abundance,affecting the efficiency and stability of the reactor.