Inorganic nitrogen control in a novel zero-water exchanged aquaculture system integrated with airlift-submerged fibrous nitrifying biofilters

This work examined the feasibility of applying shrimp diets to establish nitrification on submerged fibrous biofilters. It also investigated the performance of a proposed zero-water exchanged aquaculture system, which integrated growing of aquatic stocks and operation of acclimated biofilters in the same environment. Addition of shrimp diets fully established nitrification within 3 weeks as indicated by continuous increase of nitrate and trivial levels of ammonium and nitrite. A series of batch experiment revealed an average ammonium degradation rate of 24.1 mg N m−2 day−1. Zero-water discharged tilapia cultivation could be carried out in the proposed aquaculture system for at least 44 days when daily inorganic loadings increased from 1.24 to 10.78 mg N l−1 day−1. The corresponding daily growth rates of tilapia from the proposed aquaculture systems integrated with acclimated biofilters varied from 3.01 to 3.35 g day−1, which was approximately 7–16% better than numbers from the systems using non-acclimated biofilters.