Closing Resource Cycles in Industrial Aquaponics

Industrial aquaponics combines aquaculture, hydroponics, and anaerobic digestion to produce food while minimizing the environmental strains inherent to current linear food production by reducing, recycling, and reusing resources such as nitrogen, phosphorus, and water. This thesis investigates how such systems should be designed, monitored, and controlled, with an emphasis on resource-use efficiency and self-sufficiency, using mathematical modelling and experimental work. Results show that industrial aquaponics in stable climate regions can operate without artificial nitrogen- or phosphorus-based fertilizer. In seasonal climate zones, an external anaerobically digestible waste source (e.g., manure) is required to avoid artificial fertilizer supplementation, and the preferred manure changes with seasonality strength. Moreover, the optimal set of sensors required to measure all nitrogen- and phosphorus-containing states differs between winter and summer. Finally, lettuce was less sensitive to acetate than to isovalerate, two volatile fatty acids from anaerobic digestion. The toxicity levels found during experiments suggest that stable anaerobic digestion does not adversely affect lettuce when integrated into aquaponics. 

The candidate of the PhD defence "Closing Resource Cycles in Industrial Aquaponics".