WASTEWATER
By Rick LallishWhat type of activated sludge treatment process is used when the influent is considered nutrient deficient?A. Kraus processB. Al West methodC. Membrane bioreactorsD. High-purity oxygenAnswer: A. The Kraus process is used when the wastewater is nutrient deficient or has a greater ratio of carbonaceous to nitrogenous materials. This is usually found in dairy or cannery operations. It is a modification of a conventional activated sludge process and uses a portion of the anaerobic digester supernatant to supplement the nutrients needed for the activated sludge process. Other benefits of the Kraus process are increased sludge settleability and a ready supply of organisms. More
