Organic matter removal and CH4 production performance recoveries and microbial community changes in upflow anaerobic biofilter after long term starvation

The organic matter in municipal wastewater can be recovered by anaerobic biological treatment, making further resource utilization of municipal wastewater, which meets the requirements of sustainable development. An upflow anaerobic biofilter (UAF) treating municipal wastewater was established. The performances of stable operation and recovery operation of UAF after long-term starvation (234 days) and the changes of microbial community structure were researched. By gradually reducing HRT from 10 h to 4 h, the UAF achieved the treatment performance of pre-starvation after only 50 days recovery operation, in which total COD and soluble COD removal efficiencies reached 66 % and 69 %, respectively, and the CH₄ production rate was 0.21 L CH₄/g COD_removal. The recovery performance of UAF after long term starvation showed that the recovery sequence of three main anaerobic processes was hydrolytic acidification, hydrogen-acetate production and methanogenesis. High-throughput sequencing results indicated that dominant bacteria associated with hydrolytic acidification process changed from Moduliflexaceae and Trichococcus in stable operation stage to Trichococcus and Romboutsia in recovery stage. Besides, the dominant archaea changed from Methanosaeta (hydrotrophic methanogens) to Methanobacterium (acetotrophic methanogens), showing Methanobacterium was more resistant to starvation environment. Therefore, by using UAF for biological treatment of organic matter, even after a long period of starvation, the system would not be completely destroyed. Once it resumed operation, the treatment performance could be restored in a short period of time.