NEWTON SEA: Valorisation of agricultural wastes in the Thai rural economy for bioenergy production nutrient recycling and water pollution control

This project will build innovation capacity for the valorisation of agricultural waste materials in renewable energy production, wastewater treatment, nutrient recovery, and chemical pollution risk reduction, using aquacultures in Thailand as case study. It will protect the environment and public health by reducing open burning of biomass wastes such as rice straw, corn cobs or coconut shells and husks. These biomass waste materials will instead become feedstock for renewable energy production in biogasification plants. The main project focus is on testing the suitability of biochar, the solid residue of the biogasification process, for environmental pollution control and nutrient recovery, thus realizing multiple benefits at the intersection of the food, energy, water and environment sectors. The UK-Thai research collaboration will test the suitability of biochars produced from different agricultural waste materials under different pyrolysis conditions as sorbent material to prevent entry of toxic chemicals such as heavy metals or pesticides or petroleum hydrocarbons from polluted canal water into the food-chain of aquaculture ponds, where they could bioaccumulate and ultimately affect the consumers of shrimp, fish and other aquaculture products. Our project will test the hypothesis that biochars can be used in water biofiltration designs to enhance retention of toxic chemicals and facilitate the break-down of biodegradable pollutants such as pesticides or petroleum hydrocarbons present in canal water which feeds ponds. We will also test the hypothesis that biochars can be directly applied to aquaculture pond sediments to bind up sediment pollutants and prevent their uptake into the aquaculture food-chain. After harvest, the aquaculture ponds themselves can become the source of nutrient rich wastewaters which, if discharged into canals without treatment, will cause eutrophication of canal water and damage ecosystems. Instead of discharging nutrients into sensitiveecosystems, it would be better to recover them for use in agriculture, replacing inorganic fertilizers. The project will therefore also test the hypothesis that biochars can bind and recover nutrients from aquaculture wastewater. Contrary to more traditional wastewater treatment options based on the nitrification-denitrification process, the new process will not release precious nutrients as molecular nitrogen into the atmosphere, from where nitrogen has to be fixed again with the energy-intensive Haber-Bosch process for use in agriculture. Instead, the nutrients will be sorbed onto biochars which can then be applied to fields as slow-release fertilizer or used as nutrient source in hydroponic systems. The project will experimentally investigate the feasibility of these innovative concepts using real Thai agricultural waste materials for the production of biochar, and real canal and aquaculture pond waters and sediments for evaluating the proposed treatment methods. Water and sediment treatment design models will be calibrated and verified with the measured experimental data and utilized to optimize the proposed designs. Researchers from King Mongkut's University of Technology Thonburi (KMUTT) in Bangkok and Newcastle University in the UK will share responsibility for the delivery of this project, and will exchange biochar production & characterisation, chemical analysis, water treatment design and field work expertise. Stakeholders from Kasetsart University, the Water Quality Management Office, and Thai farmers will be engaged in two public workshops, and through the field work at an aquaculture farm. This project seeks to invert the current problematic inter-dependencies in the Food-Energy-Water-Environment Nexus into future mutually beneficial inter-linkages which will make the rural economy more sustainable. The project will create new economic opportunities, and contribute to innovation in an area of global significance.