Anaerobic Phased Solids Digester Pilot Demonstration Project

Author : Joshua Lewis Rapport
Publisher :
ISBN 13 : 9781267239457
Total Pages : pages
Book Rating : 4.2/5 (394 download)

DOWNLOAD NOW!

Download or read book Large-scale Anaerobic Digestion of Food Processing Waste and Pretreatment of Agricultural Residue for Enhancement of Biogas Production written by Joshua Lewis Rapport and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Anaerobic digestion is a waste-treatment and renewable-energy technology for wastewater and solid organic waste streams (i.e. food processing, agricultural, and municipal solid waste). This research project was designed to test a large-scale, high-solids, high-temperature, multi-stage anaerobic digester design developed at the University of California at Davis known as the Anaerobic Phased Solids (APS) Digester system. The system was tested over 10 months with 229 t cannery waste, producing 650 m3 biogas per ton of volatile solids loaded (53% methane). In addition to operational testing, heat transfer in the reactors was modeled to improve the energy balance for the system. A steady-state model was used to determine heat transfer coefficients at the insulated wall and uninsulated roof and floor, revealing that the majority of heat loss may have occurred through the floor and roof of the reactor. Wind speed, solar gain, radiative losses and air temperature appreciably influenced heat transfer rate while mixing velocity did not. The transient solution to the model matched reactor temperature over time and total heat demand at the pilot plant. An axisymmetric model was also developed to evaluate spatial temperature distribution in the reactor.In addition to digesting food waste, laboratory experiments were designed to test the anaerobic digestion of sugar beet leaves. Sugar beets are a high-yield feedstock for bioethanol with beneficial agronomic characteristics. The methane potential of sugar beet leaves was determined with and without pretreatments (i.e. sodium hydroxide and water soaking). The pretreatments were found to be moderately beneficial, but digestion without pretreatment consumed 80-85% of the volatile solids with VS-based methane yields of 280 - 320 mL/g. Furthermore, process modeling revealed that a digester co-located with a 38 dam3/y sugar-beet-to-ethanol fermentation facility could convert 726 t/d wet sugar beet leaves to 824 GJ/d as biogas (50% methane) in four 5,374 m3 reactors drawing 540 kW of electrical power, which could be produced from 14% of the biogas. After heating the digester, there would be 545 GJ/d of additional heat which could provide 55% of the energy required for ethanol production. The financial, agronomic, and environmental effects merit further study.