Hybrid nanobubble-forward osmosis system for aquaculture wastewater treatment and reuse

The discharge of untreated effluent containing excessive pharmaceutical chemicals (PCs) from aquaculture farms has caused several negative effects on the aquatic ecosystems. Herein, we used a hybrid system based on two emerging technologies, namely forward osmosis (FO) and nanobubbles (NBs), as an energy-efficient, sustainable, and effective alternative to conventional processes for the treatment and reuse of aquaculture wastewater. The combination of NB technology with FO served as a single-step treatment process for the removal of aquaculture pharmaceutical contaminants. In the hybrid system, the FO membrane removed organic matter, dissolved solids, and pharmaceutical chemical residues from aquaculture effluents with a high efficiency (∼98%), whereas NBs functioned as a physical membrane-cleaning agent that enhanced the performance and longevity of the FO membrane. Notably, the results revealed minimal contribution of NBs for the direct degradation of the tested PC i.e. oxytetracycline (OTC), where air and ozone NBs could only oxidize nearly 11% and 30% of the OTC in the water respectively. The relatively higher OTC degradation by ozone NBs was attributed to the ozone NBs-induced reactive hydroxyl radicals (HO^•) that react with OTC for its oxidative decomposition. We believe that the tested hybrid system offers a sustainable solution for aquaculture wastewater treatment as well as the recovery of antibiotics from the wastewater and will play a vital role in the sustainable development of the fisheries industry.