Wastewater Treatment: Biological

abstract Rapid urbanization and indiscriminate use of natural resources have placed the environment under increas-ing stress, and different measures are being implemented to prevent further deterioration. For example, treat-ment of our wastes and efficient reuse of our resources are prerequisites to further sustainable existence. As such, various waste treatment technologies have developed with the goal of minimizing negative impacts of wastes on the environment while also potentially recovering value from the wastes. Although many tech-nologies exist, biological processes compare very favorably with non-biological processes because of their sustainability potential, including energy production and resource recovery. Further, carbon, nitrogen, and phosphorus are the main constituents of most wastes, and removal of such elements from waste effluents can reduce environmental stress and minimize ecosystem deterioration. This summary describes typical aerobic and anaerobic biological treatment methods, including activated sludge processes, upflow anaero-bic sludge blanket reactors and other anaerobic systems, and biological nitrogen and phosphorus removal systems, which can be used to treat different types of wastes. An emphasis is placed on methods that also have the capacity to generate potential energy as combustible biogas or nutrients from wastes.