Aerobic sludge granulation at high temperature-low humidity for domestic wastewater treatment

Abstract

With inoculum sludge from a conventional activated sludge wastewater treatment plant, a sequencing batch reactor fed with domestic wastewater was operated at 50 ± 1 "C and pH 7 ±, to study the formation of aerobic granular sludge (AGS)for simultaneous organics and nutrients removal with a complete cycle time of 3 h. The AGS were successfully cultivated with excellent settling ability and demonstrated exceptional performance in the organics and nutrients removal with influent loading rate and CO/N ratio of 1.6 kg COD (L..d ):' and 8.3, respectively. Stable, regular, dense and fast settling granule (average diameter, 1.5 mm; settling velocity, 33 m h': and sludge volume index, 22.3 mL g-l) were developed in a single reactor. In addition, 96.5% COD removal efficiency was ob served in the system at the maturation stage of the granulation, while its ammonia and total nitrogen removal efficiencies were up to 94.7% and 89.4%, respectively. The study demonstrated the capabilities of AGS formation in a single, high and slender column type-bioreactor at high temperature which suitable to be applied for hot climate and low humidity countries (e.g. Saudi Arabia).