Slaughterhouses produce highly concentrated wastewater (EC, 2005), which contains high levels of biodegradable organic matter, such as faeces, undigested food, blood, suspended material (Jian and Zhang, 1999). The composition of slaughterhouse wastewater in terms of organic strength, inorganic elements, alkalinity and pH is adequate for biological treatment (Massé and Masse, 2000). Design criteria for slaughterhouse wastewater treatment plants are widely published (Travers & Lovett, 1984; Li et al, 2008). In general, variations in the composition of slaughterhouse wastewater are significant, depending on production procedures, by-product recovery and cleaning procedures (Pozo et al., 2003). The high ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) suggests easily biodegradable wastewater, the relatively low ratio of BOD to total Kjeldhal nitrogen (TKN) suggests the need for nitrification and possibly also removal of nitrogen and finally the relatively high total suspended solids (TSS) ratio characterize slaughterhouse wastewater (Chen and Lo, 2003; Lovett et al., 1984). TKN values ​​are highly dependent on the blood handling process of the slaughterhouse. The concentration of contaminants in slaughterhouse wastewater varies, with concentrations of COD, TKN and TSS ranging from 1,000 to 20,000 mg L-1, 150-10,000 mg L-1 and 250-5,000 mg L-1 respectively (Li et al, 2008). For large-scale slaughterhouses, the European Commission recommends on-site biological treatment to remove organic carbon and nutrients before wastewater is discharged to surface waters or local wastewater treatment plants (EC, 2005). This has forced many industries to treat their wastewater to a level achievable by implementing the best available wastewater technology… half the paper… for biosolids management. Environmental Science and Pollution Research 15, 308–317.31. Wei Y., Van Houten RT, Borger AR, Eikelboom D, H., Fan Y., 2003. Minimization of excess sludge production for biological wastewater treatment. Water Research 37, 4453-44671.32. Yasui H. and Shibata M., 1994. An innovative approach to reduce excess sludge production in the activated sludge process. Water skiing. Technology. 30, 11-20.33. Yang, S.-S., Guo, W.-Q., Zhou, X.-J., Meng, Z.-H., Liu, B., Ren, N.-Q., 2011. Optimizing operation parameters for sludge process reduction under alternating aerobic/oxygen-limited conditions using response surface methodology. Bioresource. Technology. 102, 9843–9851.34. Yamamoto K, Hiasa M, Mahmood T, Matsuo T. Direct solid-liquid separation using a hollow fiber membrane in an activated sludge aeration tank. Water science technology 1989;21:43±54.