Nitrogen cycling and resource recovery from aquaculture wastewater treatment systems: a review

The rising aquaculture industry has induced an increase in aquaculture waste, calling for advanced methods to recycle waste in the context of the circular economy. Here, we review methods to treat aquaculture wastewater such as the biofloc technique, aquaponic-aquaculture, rice-fish co-culture, microalgae culture, algal–bacterial culture, membrane and moving bed bioreactors, and electrochemical techniques. We discuss nitrogen cycling, resources recovery, and nitrous oxide emission and mitigations. We observed that aquaculture wastewater irrigation allows for enhanced plant biomass, and biofloc technology improves fish biomass. Nitrogen removal processes, including anammox and partial nitrification, show improved performance. Nitrous oxide emission is mainly dependent on the total ammonia and nitrite concentration.