(The 2nd IWA Malaysia Young Water Professionals Conference 2015) Aerobic granulation for real domestic sewage treatment at hot and low humidity climate condition M. H. Ab Halim*, A. Nor Anuar**, Z. Ujang** and M. M. Bob*** * Department of Environmental Engineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia (E-mail: hakim_90@rocketmail.com) ** Institute of Environment and Water Resource Management, WATER Research Alliance, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia (E-mail: aznah@utm.my) *** Department of Civil Engineering, College of Engineering, University of Taibah, 30001 Universities Road, Al Madinah Al Monawarah, Kingdom of Saudi Arabia (E-mail: mustafambob@gmail.com) Abstract With inoculum sludge from a conventional activated sludge wastewater treatment plant, a sequencing batch reactor fed with real domestic wastewater was operated at 50 ± 1 °C 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 of 1.2 kg COD m −3 d −1 . Stable, regular, dense and fast settling granule (average diameter, 2.0 mm and sludge volume index, 73.501 mL g −1 ) were developed in a single reactor. In addition, 89 % COD removal efficiency was observed in the system at the maturation stage of the granulation, while its ammonia nitrogen removal efficiencies were up to 99 %. The study demonstrated the capabilities of AGS formation in a single, high and slender column type- bioreactor at high temperature which is suitable to be applied for hot climate and low humidity condition (e.g. Saudi Arabia). Keywords Aerobic granular sludge; sequencing batch reactor; high temperature; hot climate; domestic wastewater; wastewater treatment INTRODUCTION Domestic wastewater treatment in urban areas is one of the crucial elements to be considered in the development of a country in order to sustain individual’s health and welfare. Untreated wastewater can lead to spreading of disease in the form of several types of endemic and epidemic illnesses (Ahmad et al., 2008). There are various kind of wastewater treatment applications nowadays ranging from modest, low priced, and less efficient processes to very advanced, highly efficient and pricey operations. The selection among these processes should acknowledge local area circumstances such as climate and weather, social attributes, economy, availability of enforceable standards, availability of land and power, demanded operation skills and its availability, monitoring actions, effluent discharge options as well as effluent reuse applications and conditions (Ahmad et al., 2008). Currently, several types of the widely-used wastewater treatment technologies include activated sludge process (ASP), sequencing batch reactor (SBR), up-flow anaerobic sludge blanket reactors associated with facultative aerobic lagoon (UASB–FAL) and constructed wetlands (CWs) (Kalbar et al., 2012). Aerobic granular sludge (AGS) has been widely studied in recent years (de Kreuk et al., 2005a). AGS is made up of a dense cluster of symbiotic organisms, with good biological activity performance and excellent mass transfer efficiency. Aerobic granular sludge-based reactors represent an appealing option over conventional activated sludge systems due to their small footprint and low excess sludge production (de Bruin et al., 2004). The sludge developed in such systems acquires high biomass concentration, better settling properties, high chemical oxygen demand (COD) removal efficiency, and good phosphorus removal capacity (de Kreuk et al.,