Recovery and re-use of energy, water and nutrients from waste in the food chain (Redivivus)

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SummaryThis project will study the ambitious task of redefining the role of a typical food and farm waste AD plant. Instead of just the production of biogas for heat and energy, and digestate for soil remediation, we will consider an AD plant as an energy, nutrient and water recycling facility. An approach to energy conservation will be developed in order to demonstrate a series of integrated technical solutions that have significant short-term economic and longer-term societal and environmental impacts, ultimately contributing to the Government's greenhouse gas emissions reduction targets and obligations under the European Landfill Directive. The UK has a highly successful agricultural industry and the food and drink supply chain is our largest manufacturing sector accounting for 7% of GDP and employing 3.7 million people. At 20% of UK purchase expenditure, food and drink is also our biggest consumer spending category. With imports of around 40% of the total food consumed (and rising) Britain is not self-sufficient in food production. Almost half of the vegetables and a significant proportion of the fruit eaten in the UK come from abroad. When combined together with home grown produce, and considered from a different food chain perspective, the UK wastes substantial quantities of food. Some estimates suggest that somewhere between 30-50% of all food grown and imported to the UK is destined to become food-waste. Food waste in the UK is the subject of environmental, economic and social concerns that has received widespread media coverage and met with a range of significant responses from the Government. Various objectives have been set, including the ambitious target of recycling food waste by increasing anaerobic digestion (AD) plants from 134 plants in 2013 to 1,000 plants by 2020. Simultaneously, it is estimated that primary energy production from biogas (in the EU-27) will increase by 382% between 2010 and 2020. Technologies will be investigated that could enable the following: (a) Separation of CO2 from CH4 in biogas for higher calorific value heat and power, direct gas-to-grid injection and as a liquid gas farm vehicle fuel.(b) Re-use of separated CO2 in CH4 heated greenhouses for enhanced crop growth, providing a cash-crop for AD operators/livestock farmers and (once commonplace for AD plants) reducing food imports.(c) Coagulation and re-use of nutrients (P, N, minerals) in digestate in order to recycle fresh water and provide fertilizer for arable soils and greenhouse grown (hydroponics) crops.(d) Use of crop bio-char as a carrier for recycled nutrients (P, N, minerals), transferring carbon from the atmosphere into useful carbon deposits in arable/horticultural soils, thereby taking it out of the short-term carbon cycle and into longer term non-atmospheric carbon pools. (e) Modelling alternative approaches for the most effective recovery and re-use of energy and resources generated by AD taking into consideration societal, economic, and environmental factors and interactions with the national energy supply system. (f) Understanding the economics and societal impact of the novel strategies advocated by Redivivus for energy and resource recovery.The project therefore represents an opportunity to innovate an expanding AD market within Europe. The research required to support this change in concept needs a broad based, problem solving and multidisciplinary approach that considers societal as well as technological change. By using energy, nutrients and water from food waste to grow crops and reduce food imports at home, this project has added value in that it will contribute to ending the global food crisis that leaves millions worldwide starving and impoverished.