Evaluation of a membrane biological reactor for reclaiming water, alkalinity, salts, phosphorus, and protein contained in a high-strength aquacultural wastewater

The capacity of a membrane biological reactor to provide nitrification, denitrification, and enhanced biological phosphorus removal of a high-strength aquaculture backwash flow (control condition), or the same flow amended with 100 mg/L of NO3–N and 3 mg/L of dissolved P (test condition), was assessed using only endogenous carbon. Permeate TSS and cBOD5 concentrations were <1 mg/L under control and test conditions, achieving 99.97–100% removal efficiencies, respectively. Permeate TN concentrations were 1.8 ± 0.5 mg/L and 2.1 ± 1.4 mg/L, while permeate TP concentrations were 0.05 ± 0.01 mg/L and 0.10 ± 0.03 mg/L, respectively, under control and test conditions. Our findings suggest that permeate flow could be reclaimed to recycle alkalinity, salts, and heat for fish culture and that the waste activated sludge does not produce metals concentrations that would prevent its land application (reclaiming phosphorus) or prevent its use as a protein source in animal feeds.