Evaluation of Treatment Processes for Aesthetic Quality Improvements of Groundwater

摘要

The inferior taste of drinking water in many communities results in substantial portions of customersbuying bottled water or installing point-of-use treatment systems at relatively high expense. Pilotplant testing for improved sulfide, iron and manganese removal in groundwater supplies wasconducted at the Scotts Valley Water District, California, to find water treatment processes thatwould produce the taste and flavor of the public water supply equivalent or better than bottled orpoint-of-use treated water. It was found that a consumer taste and flavor panel provided a muchbetter indication of aesthetic water quality than analytical laboratory threshold odor number (TON),testing. Pilot plant testing of manganese dioxide (pyrolusite) filter media, ozonation, and high sulfideremoval granular activated carbon, (GAC), was conducted at three of the District’s groundwatertreatment plants. In addition, hydrogen sulfide stripping packed tower aeration and alternative sulfideodor scrubbers were also evaluated. Capital and operation costs were then developed, whichindicated that better tasting water could be delivered to the customers at substantially less overallcost than the bottled water and/or point-of-use treatment that were currently being used by mostcustomers. The taste and flavor panel blindly rated on a simplified taste scale of 1 to 5 with 1 being“Awful,” 3 being “Mediocre” and 5 being “Very good.” All tests of waters were chlorinated to about 1mg/L and stored overnight to simulate system operation storage conditions. Fifteen flavors wereused to identify the perceived flavor of the water with sulfurous, chemical, metallic or chlorinousbeing most often listed.