Ammonia Capture With Biogas Purification From Anaerobically Digested Poultry Litter

BACKGROUND Poultry litter (PL) has a high solid and organic nitrogen content that is converted into NH(3)during anaerobic digestion (AD), requiring the dilution of PL influent prior to AD. With nutrients extracted from the AD effluent, the water could be reused for influent dilution or for other purposes, while creating a designer nutrient product from the PL matrix. The study goal was to determine the effectiveness of an ammonia (NH3)-stripping and scrubbing system to remove and capture NH(3)from anaerobically digested PL. After NH(3)stripping, a novel, patent-pending dual-vessel NH3-scrubber system was designed to simultaneously capture the stripped NH(3)while producing higher quality biogas through partial removal of non-combustible carbon dioxide (CO2) and corrosive hydrogen sulfide (H2S). RESULTS The stripping reactor reduced total ammonia nitrogen (TAN) by 84.6-90.4% when loaded with an ammonium chloride solution or screened PL digestate after 4 h, while the scrubber captured 73.3-76.2% of the stripped NH(3)when proxy biogas streams (59-60% CH4, 40% CO2) with two H2S concentrations (0.1 or 1% H2S) were used. The scrubber reduced CO(2)and H2S concentrations in the biogas by 3.9% and 23-29%, respectively. CONCLUSION The study demonstrated a novel NH(3)stripping-and-scrubbing system that successfully reduced TAN in anaerobic digestate, captured the stripped NH3, and reduced CO(2)and H2S concentrations in biogas. The novel design can be used to increase the adoption of AD for PL by providing a useful NH(3)fertilizer, wastewater with less NH3, and a biogas stream with less H2S. (c) 2020 Society of Chemical Industry (SCI)