Of all industrial activities, the food sector has one of the highest consumptions of water and is one of the biggest producers of effluents per unit of production; in addition they generate a large volume of sludge in biological treatment [4]. In aerobic systems, the sludge production is about 0.5 kg per kg of removed chemical oxygen demand (COD) and in anaerobic systems about 0.1 kg per kg of removed COD [70]. Due to high pollution load of dairy wastewater, the milk-processing industries discharging untreated/partially treated wastewater cause serious environmental problems [5]. Nutrients present in dairy effluent such as nitrogen and so forth lead to eutrophication of receiving waters [6].