Recovery of Anaerobic Digesters upon Hydraulic Shock-Loading through Addition of Compost and Leachate

摘要

The objective of this study was to test if readily available seeds, namely MSW compost and landfill leachate, could improve the recovery of anaerobic digesters after a hydraulic shock. For this purpose, a 14-L digester was fed with food waste at OLR of 2.5gVS/l/d and HRT of 30 days. Upon a hydraulic shock, specific methane generation decreased and VFAs, notably propionate and acetate, spiked, necessitating a reduction in OLR to 2 gVS/l/d. After 2 HRTs, compost and leachate were added to the digester to speed up the recovery process. As a result, specific methane generation increased to ～11% higher than pre-shock rates and soluble COD and total and free ammonia decreased to ～30% lower than initial concentration. Most importantly, VFA concentrations dropped back to initial levels. Similarly, convergence (at the order of magnitude level) of predominant methanogenic orders (Methanobacteriales and Methanosarcinales) was observed. Based on the above, the addition of MSW compost and leachate improved the recovery of anaerobic digesters to hydraulic shock loading.