Grant: Alliance Grants

Food waste generated in the healthcare system such as hospitals has economic and environmental impacts. In this regard, waste-to-energy technologies have been identified as one of the options to be explored in the Sustainability Plan of Providence Health Care (PHC), our partner organization. Anaerobic digestion (AD) is a proven eco-friendly technology to reduce GHG emissions and hence the carbon footprint of waste management operations. Moreover, the use of small-scale digesters can play a valuable role as a decentralized renewable energy generation system. Pressure swing adsorption (PSA) remains an effective technology today for upgrading the biogas generated from AD to renewable natural gas (RNG) among various physical and chemical techniques. The proposed project aims at developing an inexpensive adsorbent material that is alternative to commonly used commercial adsorbents in a PSA system. To begin with, biochar derived from catalytic pyrolysis of the food waste AD residual (digestate) will be activated to enhance the biochar characteristics and eventually the adsorption capacity of CO2 in the biogas. This approach has not been used in studies to-date on biogas upgrading. Experiments using a pilot-scale AD system will then be conducted to assess the effectiveness of the modified biochar as the PSA adsorbent for ex-situ upgrading of biogas to produce RNG. In-situ enhancement of biogas production and its methane content with addition of biochar to the AD reactor will also be evaluated. Investigation is extended to additional recovery of resources in the form of mature compost and reclaimed water from the AD digestate. The finished compost will be utilized as a plant growth medium for growing tomatoes in a community garden at PHC. The project also involves integrated life cycle environmental impact and technoeconomic assessments on the entire waste-to-resource recovery system based on the pilot-scale test results, with an aim to delineate and recommend the best waste management approach to process and utilize food waste that is generated in the PHC health care facilities, which would eventually be applicable to other facilities in British Columbia and Canada.