Back to Bacteria: A More Natural Filtration

by Bruce E. Rittmann, (M.ASCE), Professor and Area Coordinator of Environmental Health Engineering; Northwestern University, Evanston, IL,

Serial Information: Civil Engineering—ASCE, 1996, Vol. 66, Issue 7, Pg. 50-52

Document Type: Feature article

Abstract: Drinking-water treatment used to be simple: use the best source available, filter if turbidity is present and add plenty of chlorine. Typically, these are the barriers that guard against distributing pathogenic microorganisms, which is the main objective of drinking-water treatment. Although chlorine is an effective disinfectant against many pathogenic microorganisms, its use creates other problems. When chlorine doses are highest, particularly in the summer, the water has a characteristic chlorinous or swimming pool taste and odor that generate customer complaints. Regulations are forcing reduction in chlorine doses to minimize the formation of disinfection by-products (DBPs) having known or suspected health impacts on humans. While chlorine is an effective disinfectant in some cases, it is not a universal fix for all pathogenic microorganisms that can contaminate water. With limits on chlorine coming down the pike, water utilities must turn to other technologies to ensure that the water is safe and tasty at the consumer's tap. To ensure the microbiological safety of water, utilities are using alternate disinfectants and emphasizing filtration. Filtration is the most important barrier against all types of pathogens because all microorganisms are particles that can be physically removed in a properly designed and operated filter. The biofilm system--a modified filtration process--offers a reliable, economic alternative to large doses of chlorine for drinking-water utilities.

Subject Headings: Biofilm | Chlorine | Drinking water | Filtration | Pollution | Water treatment |

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