ENVS 65 Lecture Notes - Lecture 4: Eutrophication, Secondary Treatment, Activated Sludge
Document Summary
Secondary treatment: secondary treatment uses biological processes found in nature to remove additional organic materials suspended in the water. Microbial biologists have searched rivers and wetlands and identified and isolated certain species of bacteria, protozoa, and other microbes that consume the organic materials found in primary effluent. Primary effluent is first aerated to increase its oxygen content. It then slowly passes through large chambers with ideal habitat conditions for the desired bacteria. The water passes over the bacteria, which may be attached to the roots of growing plants or to filter screens in a form of sludge (called the. These systems are typically called the activated sludge process, trickling filters, or rotating block filters. Sometimes ponds or lagoons are used for this treatment step. Having passed through this step, the water then flows to the second set of clarifiers, called secondary clarifiers. Their purpose is to remove any of the activated sludge that entered the water stream during secondary treatment.
