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In water distribution systems containing PVC pipe manufactured in the 'early era' (prior to 1977), vinyl chloride can leach into drinking water resulting in vinyl chloride concentrations exceeding the 2 [micro]g*[L.sup.-1] maximum contaminant level. Field testing of dead-end segments of water distribution systems consisting of early-era PVC pipe was conducted to examine their initial intrapipe vinyl chloride monomer (VCM) concentrations based on a Fickian-diffusion-based leaching model. The experiments showed a wide range of VCM concentrations within early-era PVC pipe ranging from less than 50 to more than 600 mg*[kg.sup.-1]. Based on the diffusion modeling approach, a protocol was designed that provides a means for utility managers to calibrate the model for specific dead-end lines. The paper delineates procedures to determine which dead ends require flushing to control vinyl chloride, examines the effects of system parameters such as temperature on vinyl chloride leaching, and provides a method to devise flush schedules and volumes. Through a properly designed, tested, and maintained flush protocol such as that developed in this research, public water systems with dead-end lines consisting of early-era PVC pipe can control vinyl chloride concentrations using either manual or automatic flush valves. DOI: 10.1061/(ASCE)0733-9372(2003) 129:9(844) CE Database subject headings: Potable water; Water distribution; Polyvinyl chloride; Models.

This paper presents the results of a laboratory study on the effect of pH (2, 5, and 9) and gas-phase ozone concentration (1, 7, and 11 wt %) on the decolorization efficiency via ozonation for seven common textile dyes. Higher gas-phase ozone concentrations resulted in higher decolorization rates due to more rapid ozone transfer. Higher gas-phase ozone concentration, however, was also observed to have a positive, neutral, or negative effect on ozone dose requirements for different dyes. In general, greater ozone utilization efficiency was achieved at lower pH levels where direct ozone reactions predominate. It was observed that because ozonation can cause significant resolubilization of precipitated dyes, complete removal of dye precipitate should be accomplished prior to polishing via ozonation. The results point to the need for laboratory and/or pilot testing for dye-laden wastestreams to allow process optimization. DOI: 10.1061/(ASCE)0733-9372(2002)128:3(293) CE Database keywords: Ozone; Dyes; Laboratory tests; Wastewater.

Researchers from Clemson University, University of Missouri and CH2MHill conducted studies on the pretreatment of four classes of compounds using ozone/hydrogen peroxide (O3/H202) advanced oxidation process and was able to show that different amounts of oxidants are required to remove 85% of dissolved organic carbon in batch bioassays.

Widespread use of s-triazine herbicides such as atrazine, simazine, and cyanazine has led to the contamination of many ground-water and surface-water supplies with the parent compounds as well as by primary metabolites (e.g., deethylatrazine, deisopropylatrazine, and deethylcyanazine). Ozonation has been shown to produce many of the same byproducts. Activated carbon adsorption has been designated by the U.S. Environmental Protection Agency as the best available technology (BAT) for the treatment of herbicides in drinking water. Little data is available, however, on the applicability of activated carbon treatment for the control of the primary degradation products of herbicides. In this study, the adsorption of deethylatrazine, deisopropylatrazine (deethylsimazine), and deethylcyanazine on powdered activated carbon (PAC) was examined including development of Langmuir and Freundlich isotherm coefficients. It was found that deethylatrazine, deisopropylatrazine and deethylcyanazine were readily treatable using powdered activated carbon (PAC). However, the PAC's adsorptive capacity for deethylatrazine, deisopropylatrazine, and deethylcyanazine was generally less than for atrazine resulting in higher estimated carbon costs.

The industrial solvent 1,4-Dioxane is a suspected carcinogen that is widely used in dyes, waxes, resins and oils. It is non-biodegradable by the microorganisms typically used in biotreatment processes and if it is not removed from industrial wastewater effluents usually goes on to become a groundwater contaminant. The use of ozone, in conjunction with hydrogen peroxide, as a means of enhancing the biodegradability of 1,4-Dioxane is discussed.

The determination of the primary ozonation byproducts of atrazine in natural and synthetic waters is discussed. Experimental methods involve natural water characterization, analysis for s-Triazines and sampling. Degradation experiments were conducted on a completely mixed batch reactor. Although the primary ozonation byproducts of atrazine were determined, other compounds are still substantially existent.