Aquaponics presents promising green technology for food security and climate change. This study investigated the performance and nutrient dynamics in a novel aquaponics with onsite anaerobic treatment compared with conventional decoupled and coupled aquaponics. All systems demonstrated good performance with fish survival rates of >97 %, feed conversion ratios of 1.3, and high lettuce production of 6.9–11.8 kg/kg-feed. The recovery of N and P (from their concentrations in the feed) was 21 % and 16 % respectively in the decoupled aquaponics, and 24 % and 18 % in the coupled aquaponics. Recovery of N and P in the novel aquaponics was 41 % and 36 %, respectively, which led to enhanced total nutrient utilization efficiency of 76 % N and 80 % P. The latter was due to the high recovery of N and P from the fish sludge. The novel system also demonstrated 1.6× higher plant areal productivity, 2.1× lower water usage, and 16 % less energy consumption per kg of feed relative to the other tested (conventional) systems. It was postulated that coupled aquaponics with anaerobic digestion is a sustainable solution that may promote a circular economy, especially in arid zones with high radiation and temperature.
