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The primary objectives of this study were to optimize granular activated carbon (GAC) treatment to meet more stringent trihalomethane (THM) standards, to estimate the costs of optimized GAC treatment, to identify by‐products of the final disinfection of GAC‐treated water, and to assess the ability of the rapid small‐scale column test (RSSCT) to simulate total organic carbon (TOC) breakthrough from pilot‐scale carbon contactors. The lowest THM concentration achievable by means of GAC treatment was found to be 10 μg/L. It was concluded that this type of treatment is expensive for the control of THMs, the predominant by‐products of postdisinfection of GAC effluents with chlorine or chloramines. The RSSCT was shown to be an economical means of estimating pilot‐scale TOC breakthrough, which can be used in making preliminary estimates of carbon utilization rates and cost estimates.

Surface‐water treatment plants are required by the Surface Water Treatment Rule to remove viruses and Giardia lamblia cysts or to inactivate them to specific levels. Particle removal data can be used to demonstrate the level of Giardia removal provided by the treatment system. This article presents the results of particle removal by two clarification‐filtration treatment trains and investigates the effect of preoxidation on process performance. The enhanced removal of particles during filtration, when ozone was used as the preoxidant, was a significant advantage of ozone over chlorine, chlorine dioxide, and potassium permanganate.

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ROM FERTILIZERS TO FRAGRANCES and food additives to flame retardants, chemicals fuel modern society. With innovations in science and technology, synthetic organic chemicals (SOCs) are constantly synthesized, reformulated, and applied in new ways. With trace levels found in utility source waters, much uncertainty remains about the significance and potential health effects of SOCs. The unknown effects of exposure to unregulated trace organics can influence public perception about drinking water safety and drive treatment decisions. Some common groups of organics found at trace levels are ■ pharmaceuticals and personal care products (PPCPs), ■ endocrine disrupting compounds (EDCs),■ contaminants of emerging concern (CECs), and ■ pesticides. These chemicals are pervasive, because most people use them in the form of prescription and over-the-counter pharmaceuticals, antibiotics, hormones, food additives, fragrances, herbicides, insecticides, cleaners, plasticizers, flame retardants, and many other common products. Many of these chemicals are present in wastewater and, if not removed during treatment, enter the environment through treated wastewater discharges. The presence of these trace organic chemicals in drinking water sources isn't new. Recent attention to chemical residues and by-products is a result of frequent occurrence as well as the ability to detect them at ultra-low levels. Detection capabilities have outpaced the ability to understand the health significance of ultra-low concentrations of organic chemicals in drinking water.Emerging Contaminants