Water energy food nexus model: an integrated aqua-agriculture system to produce tilapia and sweet basil using desalinated water

Abstract

Abstract   Under the framework of Water-Energy-Food Nexus, this study investigates the integration of solar-powered desalination with aquaculture and agriculture production systems to grow crops. Brackish water desalination is performed using reverse osmosis (RO), the permeate is directed to an aquaculture unit, and the fish effluent is used as irrigation water for crops. The experiment followed a split-plot design with three main variants: a full irrigation schedule for the basil plants with fish effluents as fertilizers, irrigation as fertigation with chemical fertilizers, and a mixed treatment of effluents and chemical fertilizers at 50% application each. Each treatment was further sprayed with or without foliar nutrient application. RO results gave a permeate recovery of 22%, and a salt rejection of 98.7%. In the aquaculture unit, tilapia harvest weight was 0.458 kg with a survival rate of 97.7% and harvest yield of 25 kg/ m3 of water. Effluent treatment exhibited the highest branching and plant height irrespective of the cut number, reaching 17.7 branches and 62-cm height. The effluent treatment under foliar application recorded the highest fresh and dry weights of basil with 14.7 ton/ha and 4.7 ton/ha, respectively. Effluent irrigation plus foliar application recorded basil yield of 5 kg/m3 effluent water. The dominant essential oil elements were linalool (55.5–61.6%), tau.-cadinol (5.3–8.3%), eucalyptol (5.4–7.7%), eugenol (2–6.8%), and (Z,E)-.alpha.-farnesene (3–5.2%). The study is among the very few integrated systems and, in particular, the current study is the first-time investigation of an integrated desalination, aquaculture, and agriculture production using renewable energy. Therefore, results suggest that integrating desalination, aquaculture, and agriculture could be a potential solution for the global water, energy, and food challenges.