1 Integrated management of wastewater and domestic organic waste in small communities E. Katsou 1 , S. Malamis 2 , L. Lijó 3 , S. González-García 3 , M.T. Moreira 3 , F. Fatone 4 1 Department of Mechanical, Aerospace and Civil Engineering, Brunel University, Kingston Lane, Uxbridge Middlesex UB8 3PH, United Kingdom. 2 Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Greece; 3 Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela. 15782- Santiago de Compostela, Spain. 4 Department of Biotechnology, University of Verona, Strada Le Grazie 15, I-37134 Verona, Italy. *Corresponding author: Tel.: +30 2107723108; e-mail address: malamis.simos@gmail.com Abstract The feasibility of the combined treatment of domestic wastewater and domestic organic waste (DOW) generated in a small community (2,000 population equivalent) was evaluated. Different schemes were investigated for the co-treatment of domestic wastewater and DOW by considering the use of food waste disposers at different integration levels (100% and 50%) as well as the source collection and treatment of DOW. The examined technologies were the upflow anaerobic sludge blanket (UASB) for energy recovery coupled to a sequencing batch reactor (SBR) to remove nutrients, the anaerobic membrane bioreactor without any post treatment of the effluent, the fermentation process of DOW to provide a liquid rich in volatile fatty acids which can be used as an external organic carbon source for nutrient removal in the SBR as well as to increase biogas production in the UASB process and the composting unit for the stabilisation of the generated sludge. The applied treatment schemes result in valuable products, such as electricity and heat from the combustion of the biogas and soil conditioner from the sludge treatment. The carbon source provided by the DOW can be used to remove nutrients in the SBR and increase biogas production in the UASB. The application of nitritation/denitritation as opposed to conventional nitrification/denitrification saves significant amount of carbon source that can be applied to the UASB process increasing the energy recovery or can be used to remove phosphorus. When conventional denitrification is applied the carbon source provided from the fermentation liquid of FWDs is enough only to remove nitrogen. Keywords Small and decentralised treatment systems; environmental profile; food waste disposer; nitrogen removal; resource recovery. Introduction In small and decentralized communities the local treatment of domestic wastewater and domestic organic waste (DOW) can be beneficial, decreasing the cost for the development and operation of long sewer networks and pumping stations as well as the transportation of DOW to centralized facilities (Massoud et al., 2009). Furthermore, the potential co-treatment of DOW and domestic wastewater can be a sustainable option leading to energy and materials recovery with significant environmental and economic benefits for the community. In this context, treatment processes that convert waste into resources currently constitute a challenge (Nakakubo et al., 2012). Effective waste and wastewater treatment and resource recovery can be accomplished by applying innovative and conventional anaerobic and aerobic processes, in order to address site specific conditions for wastewater treatment (Katsou et al., 2014). Small and decentralised systems are not only a long-term solution for small communities, but also a reliable and cost effective option (Massoud et al., 2009). Food waste disposers (FWDs) can be applied for the collection of source separated DOW within households (Battistoni et al., 2007). Their use can be an interesting option to integrate the management of domestic wastewater and household organic waste in small and decentralised communities. The application of FWDs decreases the frequency of transportation of DOW and produces less odours compared with the technologies which apply separate collection and transportation of DOW to centralized treatment facilities (Marashlian and El-Fadel, 2005). The alternative to FWD is source separation and collection of DOW which is then sent to a