(334a) Life Cycle Assessment of Resource Recovery Technologies on Large-Scale Dairy Farms

Large-scale production of livestock for dairy products has a significant impact on the environment through greenhouse gas emissions, water pollution, and resource consumption. In particular, manure management at large-scale concentrated animal feeding operations (CAFOs) poses risks to air, water, and soil quality.

However, manure is also a rich source of organic matter, nutrients (nitrogen and phosphorus), and water. Resource recovery technologies offer a way to recycle valuable compounds in manure into beneficial products while simultaneously reducing harmful emissions. In this research, a novel Nutrients, Energy, and Water Integrated Recovery (NEWIR) system is compared to a typical California dairy CAFO with life cycle assessment (LCA) methodology. NEWIR consists of three innovative processes for integrated resource recovery from dairy manure: 1) hydrothermal carbonization (HTC) for energy, 2) algal raceway ponds for nutrients, and 3) membrane distillation (MD) for high-quality water. HTC creates a carbon-rich hydrochar and a nutrient-rich aqueous stream. Hydrochar can be burned in conventional coal power plants, replacing a fossil fuel with a renewable form of bio-energy. The aqueous HTC effluent serves as a water and nutrient source for microalgae that are used as a protein-rich cattle feed supplement to offset soybean production. Finally, MD uses waste heat from HTC to recover high-quality water from the algae effluent that is reused on-farm for cleaning and sterilization, replacing conventional reverse osmosis. LCA results are used to evaluate how resource recovery technologies affect relevant environmental impact categories such as carbon footprint, water footprint, and eutrophication. The life cycle inventory is developed from experimental data and modeling for a full-scale NEWIR system and analyzed using the ReCiPe impact assessment method. Results will be presented for a full-scale model of the NEWIR system, including avoided products due to resource recovery. By creating useful products from a biowaste stream, NEWIR paves the way towards sustainable food production on a large scale.