As global population and stress on our natural resources increases, we need to rethink how/where we produce food with emphasis on recycling resources such as carbon, water, and nutrients. Controlled environment agriculture (CEA) is gaining increasing attention due to its potential for improving resource use efficiency compared to traditional field-based agriculture. This project investigated a novel approach for treating hydroponics irrigation water and recovering nutrients from vegetable waste for reuse in CEA systems. An integrated anaerobic/aerobic biological treatment process was investigated. Anaerobic digester effluent was nitrified via an aerobic membrane bioreactor process to produce a liquid organic fertilizer supplement (nADE). The nADE was evaluated as a nutrient source for indoor hydroponic and greenhouse soilless drip-irrigation lettuce cultivation. Lettuce yield, tissue nutrient content, water quality, and nutrient uptake efficiency were compared between the nADE treatment and a commercial fertilizer control for each CEA system. The lettuce grown on nADE demonstrated similar or higher yields, more leaves, and elevated tissue nutrient content than the control. The nADE media improved N and P uptake efficiency in the drip-irrigation system but decreased K, Ca, and Mg uptake efficiency, possibly from the over-application of these nutrients. Further research is needed to optimize the integrated treatment system as well as nADE dosing. The study demonstrates a circular bioeconomy approach to decrease dependency on inorganic fertilizers while benefiting crop yield and quality.
