Anaerobic pretreatment of industrial wastewaters has become increasingly popular in recent years. This is due to the vast amount of development work that has been done to commercialize the concept, to stricter environmental regulations, and to the increasing cost and decreasing availability of energy. Anaerobic pretreatment used either in advance of existing on-site aerobic systems or prior to discharge to a municipal sewer system has been shown to be a cost-effective method for wastewater treatment. It is especially attractive when there are high municipal treatment fees or when a production facility intends to expand.