推广生活垃圾分类收集与资源化利用有助于促进资源节约型?环境友好型社会建设.本文综述了我国生活垃圾分类发展历程;收集了国家和地方在推广生活垃圾分类过程中所做的工作;提炼出了生活垃圾分类过程中还存在的障碍和瓶颈;并给出了相应的对策.本文分析表明,我国生活垃圾分类经历了开始(20世纪90年代)?试点探索(2000～2015年)和快速发展(2016年至今)3个阶段.目前国家和地方正逐步采用可操作性强的垃圾分类方法?融合互联网+的宣传方式?实用性的法规章程?完善的分类收集-分类运输-分类处理循环链来推进生活垃圾分类,甚至生活垃圾分类工作还逐步向市场化方向发展.我国将走出一条切实可行?可复制?可推广的高效生活垃圾分类模式.后期加强全民参与及大众自觉回收的责任意识?出台更细化具体?操作性强的实施方案?重视学校儿童的垃圾分类教育?充分利用国内拾荒人员,对快速推进我国生活垃圾分类进程具有重要意义.

To explore the relationship between process stability and microbial community in anaerobic digestion, organic loading rate (OLR) disturbances were introduced into an anaerobic digester treating food waste (FW) to induce different process stages. Physico-chemical analysis along with the 454-pyrosequencing microbial technique were performed to monitor the responses of state parameters as well as the dynamics of microbial community. Results showed that balanced community structure ensured the stable operation of the digester. Under steady-state conditions, the methane yield reached (0.50±0.01) LCH4/gVS and volatile solids (VS) removal rate reached (89.58±0.08) %. Under high OLR conditions, the relative abundance of acid-producing bacteria (phyla Tenericutes and Actinobacteria) increased dramatically, which induced the proliferation of syntrophic fatty acid degrading bacteria (class Clostridia), while the abundance and activity of syntrophic hydrogenotrophic methanogens decreased. The imbalance relationship between methanogens and syntrophic fatty acid degrading bacteria caused their inefficient syntrophy, eventually resulting in volatile fatty acid (VFA) accumulation and process deterioration. Moreover, the accumulated VFA and ammonia reduced the specific acetoclastic methanogenic activity (SAMA) and specific methanogenic activity (SMA) by 60.12% and 72.51%, respectively, which further deteriorated the digestion process. Although the digester afterwards recovered to its original operational conditions and process performance, the microbial community profile changed and achieved new steady-state conditions.

BACKGROUND:Anaerobic digesters become unstable when operated at a high organi c loading rate (OLR). Investigating the microbial community response to OLR disturbance is helpful for achieving efficient and stable process operation. However, previous studies have only focused on community succession during different process stages. How does community succession influence process stability? Is this kind of succession resilient? Are any key microbial indicator closely related to process stability? Such relationships between microbial communities and process stability are poorly understood.RESULTS:In this study, a mesophilic anaerobic digester for treating food waste (FW) was operated to study the microbial diversity and dynamicity due to OLR disturbance. Overloading resulted in proliferation of acidogenic bacteria, and the resulting high volatile fatty acid (VFA) yield triggered an abundance of acetogenic bacteria. However, the abundance and metabolic efficiency of hydrogenotrophic methanogens decreased after disturbance, and as a consequence, methanogens and acetogenic bacteria could not efficiently complete the syntrophy. This stress induced the proliferation of homoacetogens as alternative hydrogenotrophs for converting excessive H2 to acetate. However, the susceptible Methanothrix species also failed to degrade the excessive acetate. This metabolic imbalance finally led to process deterioration. After process recovery, the digester gradually returned to its original operational conditions, reached close to its original performance, and the microbial community profile achieved a new steady-state. Interestingly, the abundance of Syntrophomonas and Treponema increased during the deteriorative stage and rebounded after disturbance, suggesting they were resilient groups.CONCLUSIONS:Acidogenic bacteria showed high functional redundancy, rapidly adapted to the increased OLR, and shaped new microbial community profiles. The genera Syntrophomonas and Treponema were resilient groups. This observation provides insight into the key microbial indicator that are closely related to process stability. Moreover, the succession of methanogens during the disturbance phase was unsuitable for the metabolic function needed at high OLR. This contradiction resulted in process deterioration. Thus, methanogenesis is the main step that interferes with the stable operation of digesters at high OLR. Further studies on identifying and breeding high-efficiency methanogens may be helpful for breaking the technical bottleneck of process instability and achieving stable operation under high OLR.

为研究驯化对餐厨垃圾厌氧消化系统微生物群落结构的影响,在单相完全搅拌式(CSTR)反应器内,以农村户用沼气池污泥为接种污泥,进行了餐厨垃圾中温厌氧消化.反应器在3 g·L-1·d-1(以VS计)的负荷下成功启动,并连续45 d维持性能稳定,表明驯化成功.期间采用454焦磷酸测序技术分析了驯化前后系统内的微生物群落结构.结果表明,微生物群落结构与底物密切相关,驯化后细菌及古菌群落都发生明显变化.从细菌群落看,与复杂有机物降解相关的菌类显著下降(如梭菌纲(Clostridia)和(vadinHA17),而易降解碳水化合物发酵菌(如Petrimonas)和脂肪降解菌(如Erysipelotrichia)显著增加.这与餐厨垃圾易降解有机物含量高,且富含淀粉和脂肪相关.丰富的易降解有机物还使得反应器内总挥发性脂肪酸(VFA)浓度((2203±174) mg· L-1)远高于种泥水平((222.0±0.3) mg· L-1),这导致了产甲烷菌由乙酸型的甲烷鬃菌属(Methanosaeta,占85.01％)绝对主导转向氢营养型的甲烷螺菌属(Methanospirillum,占35.35％)、甲烷囊菌属(Methanoculleus,占9.89％)与之(46.97％)共同主导的局面.然而,驯化后Methanosaeta在非最优条件下依然保持主导地位,可见接种污泥的群落组成对厌氧消化系统群落结构的塑造也具有重大影响.