Implementation of a Pilot Scale Anaerobic Digester System for Swine Finishing Barn

Abstract

Abstract. A pilot-scale, mesophilic anaerobic digester (AD) system is installed at the new swine research facility at University of Missouri. The swine finishing barn has four rooms, each with individual deep-pit and ventilation system. A pull-plug system can drain the manure to a nearby lagoon or a manhole to be pumped to the AD. The AD system has three insulated, reinforced fiber-glass tanks with an individual capacity of 2800-gallons. One tank is designed for feedstock storage and mixing, and the other two tanks are for digestion research either in series (dual stage) or parallel (single stage). The design employs small biogas (generated by the AD) boiler for heating the digester tanks and system building, while excess biogas will be dissipated by a flare system. This AD does not have an engine-generator, but utilizes a feedstock-digestate heat-exchanger for heat reclamation to reduce net energy input (no waste-heat from engines). The system also includes another heat exchanger for biogas cooling to remove condensate in the biogas, along with a small iron sponge to reduce H2S concentrations to improve biogas quality. Manure scrapers were added to the manure management system to collect the manure from the deep-pit rooms frequently. Manure flows through a manhole and pumped to the storage/mixing tank by using a shredder pump. The objectives are to demonstrate AD systems for small and mid-size swine productions, quantify and characterize manure nutrient changes due to AD and storage, and develop baseline emission factors for raw and digested manure. This paper reports the design details and construction of the AD system.