Efficient anaerobic digestion of food waste to methane
Project Funded through the CALS Strategic Plan Advancement 2021 Integrated Internal Competitive Grants Program read the published article here
Overcoming long-chain fatty acid-induced inhibition of syntrophy in anaerobic digestion of food waste - reagents and strategies
External Stakeholder(s) engaged in the project:
- Institute for Advanced Learning and Research, Danville, VA 24540
- L.D. Amory Company, Inc., Hampton, VA 23669
- Western Virginia Water Authority, Roanoke, VA 24011
- Virginia Tech Dining Halls
Anticipated impact of the project to advance agriculture:
According to the USDA, in the US about 30-40% of the food supply ends up being food waste (FW), and a great portion of this material is sent to landfill causing serious negative impact on the environment (1-5). In 2010 this loss was equivalent to 133 billion pounds (218.9 pounds person) or $161 billion worth of food (1, 6). The EPA and USDA have set a domestic goal of 50% reduction in the food loss and waste by 2030 and to provide incentives for generating value added products from the unavoidable waste (1, 7). One of the ways to accomplish the latter would be to foster the development of efficient processes for anaerobic digestion (AD) of FW that will generate (i) methane or natural gas or biogas that could be used as fuel directly or for generating electricity and (ii) reduced volume solid waste for use as soil amendment or fertilizer, bedding for livestock and construction materials. An ideal final outcome would be the anaerobic conversion of FW of any type to methane at the site of generation of the material. This would be equivalent to placing a solar panel on the roof of any building for meeting the energy need at the site and selling the excess to the grid. This obvious approach remains less attractive after a high enthusiasm about 50 years ago. It is because of a foundational barrier, derailment of anaerobic microbial syntrophy, that prevents efficient digestion of food waste. This problem is further exacerbated when fats, oils, and grease (FOG) get mixed with FW. As a result, less efficient practices, such co-digestion of FW with wastewater sludges, animal manure, algal biomass, rice husk, paper mill waste and domestic wastewater are increasingly being implemented or suggested. These operations require the high-volume waste materials with high water content to be collected and taken to a centralized processing site. The addition of metals and metal ions that are toxic and end up in the digester solids and pre-fermentation with ethanol and lactic acids that increases the cost of operation have also been suggested as ways of solving the problem. The innovation of the proposed project comes from the following clear distinctions. It calls for the (i) generation of microbial consortia that will allow the conversion of FW and FOG to methane in a stable manner at the site of generation, (ii) determination of the biochemical basis for such a stability through incisive microbiome analysis using next generation high throughput omics technologies for facilitating knowledge-driven process optimization and development of high-performing designer synthetic communities, and (iii) development of methods for preserving the consortia for repeated use in the initiation and continuation and also for rejuvenating the system following a derailment of microbial syntrophy. The establishment of an infrastructure to provide the technology and continued support to the AD operators and training next generation practitioners of the art is also in the plan. This innovation is inspired by the observation that anaerobic microbial syntrophy operates smoothly in numerous natural ecological sites due to optimal partnering of the methanogenic archaea or methanogens and long chain fatty acid (LCFA) degrading syntrophic bacteria (syntrophs) and the omics technologies make it possible to tease out the biochemical basis for such collaborations.
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- Agency USEP. 2019. https://www.epa.gov/sciencematters/winning-formula-making-connections-turn-food-waste-energy. Accessed
- Agency USEP. https://www.epa.gov/sustainable-management-food/united-states-2030-food-loss-and-waste-reduction-goal. Accessed