What is a “whole effluent toxicity (WET) test?
” Whole effluent toxicity tests measure the toxicity of the effluent to living organisms. Species known to be sensitive to contaminants are exposed to various concentrations of effluent, and the effects are observed. A 48-hour test measures acute toxicity; a 7-day test measures chronic toxicity. The permit requires that the MWRA conduct toxicity tests each month. What is a “pretreatment program”? A pretreatment program is designed to prevent four major problems, caused by pollutants from industrial facilities: • interference with the treatment facility operations • pass-through of pollutants into the treatment facility’s effluent • contamination of municipal sewage sludge • exposure of the treatment facility to hazardous chemicals. The NPDES permit requires the MWRA to monitor and control the discharge of pollutants into the MWRA sewer system from industrial and commercial sources. The permit also includes extensive pollution prevention requirements for these sources. Does the permit i
