Membrane Treatment of Secondary Effluents for Subsequent Use

There is considerable interest worldwide in water reuse to conserve freshwater resources. Reclaimed wastewater can be used for a variety of purposes in agriculture, industry, municipal systems, and recreation. Each application requires a minimum quality of water, which in the U.S. can vary from conventional secondary effluent without further treatment to water that approaches the highest purity achievable. Membrane processes can be specified to remove virtually the entire range of contaminants found in wastewater, so that they can be selected to achieve the water-quality requirements of almost any reuse application. Economics will determine, however, when membrane treatment is feasible. The first phase of this project involved documenting the state of knowledge and experience in membrane applications in wastewater treatment and, more specifically, in water reuse. Such experience is far more limited than experience with membrane applications in drinking water treatment. After providing an overview of water reuse and membrane processes, this report covers state regulations and guidelines on water reuse; membrane fouling; methods of testing membranes at bench- and pilot-scales; removal of microbial contaminants; and management of concentrates. Detailed findings from a literature review and a survey of full-scale facilities employing membrane processes for wastewater treatment are provided. The report concludes with an evaluation of the potential role of membrane treatment for each of the major categories of water reuse.