Decontamination of fish aquarium wastewater by ozonation catalyzed by multi-metal loaded activated carbons for sustainable aquaculture

This study aims to promote sustainable aquaculture for fish farming practices for long-term application. The potential of catalytic ozonation was evaluated for the successful purification and recycling of fish aquarium wastewater. Before continuous testing, ozone dosage, catalyst dose, reaction time, and adsorbent dose were optimized to obtain values of 1.8 mg/min, 15 g/L, 45 min, and 150 g, respectively. During this work, two different goldfish aquarium setups were installed at the lab scale to compare the treated aquarium water (tank A) with the untreated water (tank B). Tank A was a kind of continuous tank, where the water in the aquarium was continuously treated by the catalytic ozonation process. For the first time, activated carbon (AC) loaded with iron (Fe) and zinc (Zn) (Fe-Zn-AC) was used as the catalyst for fish water purification. Around 170 L of water was conserved through water purification in comparison with a normal fish aquarium setup (tank B). The results indicated successful decontamination by the decline in parameters such as ammonia, COD, BOD₅, turbidity, and potentially toxic metals as compared to untreated fish aquarium wastewater. Additionally, catalytic ozonation (Fe-Zn-AC/O₃), was more efficient for the removal of nitrogenous compounds. It is concluded that catalytic ozonation provides more efficient removal of contaminants to facilitate the establishment of a sustainably disease-free environment and better growth of fish inside a recirculating setup.