Removal of ammonia in a modified two-phase food waste anaerobic digestion system coupled with an aerated submerged biofilter.

Anaerobic digestion of food waste can reduce its volume, generate fuel biogas containing methane, and produce solid organic residue that can be used as a soil conditioner or fertiliser. Anaerobic digestion is more promising food waste disposal method than incineration and landfilling. The hybrid anaerobic solid-liquid (HASL) system, enhanced with a submerged biofilter for ammonia removal, was proposed for food waste digestion. Application of the submerged biofilter in the HASL system operated in batch mode increased concentrations of dissolved COD and volatile fatty acids in an acidogenic reactor, and total COD removal and methane production in a methanogenic reactor. The gas production in the enhanced HASL system was 86 l while in the conventional HASL system it was 54 l after 14 days of batch process. Methane production in the enhanced HASL system was increased by 26% in comparison with the conventional HASL system.