Nitrogen recovery via aquaponics in Nepal: current status, prospects, and challenges

Aquaponics is a bio-integrated system that couples recirculating aquaculture with hydroponics. Existing aquaculture has been a continuous source of environmental degradation; however, minimal concern has been documented toward its waste management. This paper aims to review the fundamental aspects of aquaponics, its components, types and influencing factors, and also to estimate potential nitrogen recovery from aquaponics. This review also explores the nitrogen transformation pathway and discusses potential challenges for aquaponics in Nepal. The estimated the nitrogen recovery potential of aquaponics in Nepal are 3509 tonnes (t) and 7157t, equivalent to 7628t and 15558t of urea fertilizer for the years 2020 and 2030, respectively. Globally, nitrogen loss from aquaculture was estimated to be 7.52 × 10⁶ t for 2016. Developing countries like India, Bangladesh, Nigeria, etc. are also major source of existing nitrogen loss from aquaculture. For environmental and production sustainability, wastewater utilization via aquaponics is crucial, therefore, needs global attention and policy formulation. Identification of isotopic signature or abundance of stable isotopes in aquaponics helps find the exact pathway of nitrogen transformation in the system.