Recovery of anaerobic digesters upon hydraulic shock-loading through addition of compost and leachate

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.

This work was supported by the National Council for Scientific Research, Lebanon and the Masri Institute of Energy and Natural Resources at the American University of Beirut. Special thanks are extended to the United States Agency for International Development for its support in acquiring the equipment used in the experimental program. Also, special thanks are extended to Mr. M. Alarawi and Dr. S. Ali at the Bioscience Core Laboratory at KAUST.

Air and Waste Management

Conference/Event Name
108th Air and Waste Management Association Annual Conference and Exhibition - Connecting the Dots: Environmental Quality to Climate, ACE 2015

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