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Aquaculture has experienced a burgeoning growth worldwide in the last decade resulting in nearly 50% of seafood originating from aquaculture farms. However, there are less studies on the utilization of the manure produced by aquatic organisms in comparison to warm-blooded livestock. Aquaponics offers more efficient utilization of nutrients and can reduce the operational costs in aquaculture. This paper presents the results of a study to identify the optimal settings to digest fish manure through a microbial-assisted aerobic bioprocess, using endogenous heterotrophic and nitrifying bacteria. The effects of pH (5.5, 6.0 and 6.5), temperature (30, 35 and 40 °C) and duration (1–30 days) on kinetics of nitrogen mineralization were investigated and compared to a control bioreactor (carried out without pH adjustment). The mineralization dynamics for all pH-controlled bioreactors revealed that only ammonification occurred. No nitrification was observed for all three-temperature conditions and throughout the entire bioprocessing period. The mineralization process in the control bioreactor, on the other hand, followed the typical non-inhibited nitrogen mineralization (i.e., release of ammonium followed by oxidation into nitrate). However, nitrate was only observed at temperatures

This study was carried out, at both laboratory- and pilot-scale, to investigate whether the presence of phosphorus affects the nitrification process during aerobic digestion of aquaculture/aquaponic solid waste. Results from the laboratory-scale aerobic digestions indicated that nitrification did not occur throughout the entire bioprocessing period (21 days) in aerobic bioreactors containing phosphorus. The mineralization process in laboratory-scale aerobic bioreactors which did not contain phosphorus, on the other hand, followed the typical non-inhibited nitrogen mineralization (i.e., release of ammonium, NH4+ followed by oxidation into nitrate, NO3−). Results from pilot-scale aerobic digestions confirmed that the presence of phosphorus did impact the nitrification of aquaculture/aquaponic solid waste. However, analytical data and modeled parameters revealed that the presence of phosphorus significantly (P = 0.0406) delayed the onset of nitrification (lag period of 9.2 days for aerobic bioreactors without the presence of phosphorus compared to 29.3 days for aerobic bioreactors containing phosphorus, corresponding to a delay period of 3 weeks) but did not influence (P > 0.05) the nitrification kinetic parameters (i.e., maximum nitrate concentration (99.5–101.1 mg/L) and maximum rate of nitrate production (11.3–19.6 mg/L/day)).