ConclusionTreatment of high-strength wastewater presents a new chal-lenge that researchers are seeking to address. Conventional aerobictreatment systems are not suitable for treatment of high-strengthwastewaters due to the excessive demand on energy for aerationand the generation of huge amounts of sludge that needs to bestabilized and disposed of. High rate anaerobic digesters includ-ing provide attractive cost-effective and efficient technologies fortreating high-strength wastewater. The formation of immobilizedgranular sludge without any media for attachment in UASB is con-sidered a breakthrough eliminating the need for biocarriers, thusovercoming filter clogging as in AF, and providing a compact designand less capital and energy requirement compared to AFBR. How-ever, process instabilities, long time required for treatment, andfailure to comply with stringent environmental effluent standardsremain its major limitations.