Adsorption of ammonium by aerobic granules under high ammonium levels

High-strength ammonium (NH4+) wastewaters are difficult to be treated biologically. Aerobic granules are regarded as a promising technology for NH4+ removal from wastewaters. Adsorption using aerobic granules in 50-4000 mg NH4+-N/L wastewaters was studied at 30 °C. Adsorption capacity was increased with 50-1000 mg NH4+-N/L and reached plateau of 24.5 mg NH4+-N/g-volatile suspended solids at >2000 mg NH4+-N/L. Ion exchange mechanism controls adsorption at <300 mg NH4+-N/L and physisorption mechanism dominates the process at >1000 mg NH4+-N/L. The biomass of aerobic granules presents a recyclable adsorbent for NH4+ from high-strength wastewaters.