AWWA WQTC62384

Due to increased concerns regarding the potential for contamination of drinking water supplies,considerable efforts have been devoted towards enhanced monitoring capabilities of priorityinorganic and organic pollutants. Bench-scale experiments were designed and performed at theU.S. Environmental Protection Agency (U.S. EPA) Test & Evaluation (T&E) Facility in Cincinnati,Ohio, on a number of contaminants that are potential threats to the drinking water supply.The experiments were conducted to determine the dose-response (sensitivity) threshold concentrationsfor water-quality sensors when exposed to these contaminants. The types of contaminantsincluded pesticides, herbicides, and lead compounds. The specific contaminants used forthis study were commercial malathion (Real KillT™), neat glyphosate, commercial glyphosate(Roundup™), aldicarb, potassium ferricyanide, nicotine, lead nitrate, dimethylsulfoxide, sucrose,colchicine, dicamba, and anhydrous sodium thiosulfate. The test compounds were selected tosimulate some of the properties of chemical and biological agents. One multi-parameter monitorand one free-chlorine monitor were used to represent typical sensors in use at water distributionsystems. The parameters monitored were chloride, free chlorine, specific conductance, turbidity,ammonia-nitrogen, nitrate-nitrogen, oxidation-reduction potential (ORP), and pH.The bench-scale tests were conducted in a reaction vessel (4-liter beaker) using 3.5 liters ofCincinnati tap water. The tests were designed to evaluate the responses of several water qualitysensors to a number of potential contaminants [added in the increment of 0.2 milligram per liter(mg/L) every minute]. Each test was carried out for 20 minutes.The study provided the minimum detection levels of the contaminants for various water qualityparameters, which were compared to life-threatening toxicity concentrations for drinking water.Of all the parameters, free chlorine was the single most sensitive indicator in the study. Inaddition to free chlorine, specific conductance, ammonium-N, nitrate-N, ORP, chloride, and pHalso showed sensitivity for detection.Based on the study results it can be concluded that commercially available single and multiparametermonitors can trigger (below life-threatening toxicity concentrations) and providewarnings when drinking water is contaminated by toxic contaminants below life-threateninglevels (dose). Of all the parameters, chlorine was the single most important indicator of thestudy. Multiple parameters crossed the threshold limits for several contaminants namely, neatglyphosate, commercial glyphosate (Roundup™), potassium ferricyanide, and anhydrous sodiumthiosulfate Includes 4 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

19

File Size:

1 file , 700 KB