Sequencing versus continuous granular sludge reactor for the treatment of freshwater aquaculture effluents

Ammonium and nitrite levels in water are crucial for fish health preservation growth maintenance freshwater aquaculture farms, limiting recirculation. The aim of the present work was evaluation comparison two granular sludge reactors which were operated to treat streams at laboratory-scale: an Aerobic Granular Sludge - Sequencing Batch Reactor (AGS-SBR) a Continuous Flow (CFGR). Both units fed with synthetic medium mimicking recycling (1.9–2.9 mg N/L), low carbon content, operational temperature varied between 17 25 °C. AGS-SBR, inoculated mature granules from full-scale wastewater treatment plant, achieved high ammonium removal during 157 days. Even hydraulic retention time (HRT), varying 474 237 min, efficiencies approximately 87–100% observed, rate 14.5 NH4+-N/(L⋅d). Partial biomass washout occurred due extremely nitrogen concentrations feeding, could only support small portion bacteria, but no major changes on reactor performance observed. CFGR activated 98 Biomass granulation 7 days, improving settling properties up-flow velocity 11 m/h applied HRT 5 min. presented after 32 achieving average diameter 1.9 mm day 63. 10–20%, rates 90.0 main biological processes taking place AGS-SBR nitrification heterotrophic growth, while by assimilation, also presenting complete partial denitrification, caused production. Comparing both systems, 6 times higher than being suitable treating flows. On other hand, removed almost 100% content wastewater, discharging better quality effluent, less toxic treated lower