Results from two AWWA-sponsored surveys regarding characteristics of drinking water service lines in US community water systems (CWSs) are described. For a detailed review of regulatory and water chemistry characteristics of lead in drinking water, see Brown and Cornwell (2015), Brown et al. (2015, 2013), Schock and Lytle (2011), and Schock (1989), and the many related references found within these papers. PREVIOUS NATIONAL LEAD SERVICE LINE ESTIMATES AWWA conducted a similar survey in 1988, summarized by the US Environmental Protection Agency (USEPA) (1991), Weston and EES (1990), and Frey (1989). The first two references present national lead service line (LSL) estimates. USEPA (1991) reported that the methodology in the initial AWWA survey estimated 7.0 million LSLs. These estimates were revised upward to 10.2 million by USEPA, as reported in the USEPA regulatory impact analysis (RIA) for the 1991 Lead and Copper Rule (LCR) (USEPA 1991). USEPA used the same database information and findings as the AWWA effort described in Weston and EES (1990) to revise the national estimate upward, though the methodology used by USEPA is not reported (USEPA 1991). The 10.2-million estimate for the number of LSLs in the United States by USEPA in the RIA was the most-referred-to value for the number of LSLs in the United States prior to the update estimate prepared through the work conducted in this article. (either full or partial) currently present in CWSs of the United States, compared with 10.2 million estimated at the time of the original Lead and Copper Rule (LCR) (USEPA 1991); approximately 11,200 CWSs currently have LSLs compared with more than 15,000 estimated in the original LCR; 15 to 22 million people served by CWSs are estimated to have either a full or partial LSL serving their home out of a total population served by CWSs of about 293 million (7%); and approximately 30% of the CWSs surveyed (national average) reported having some LSLs in their system.

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Elevated concentrations of brominated disinfection by‐products (DBPs) have been reported recently by some drinking water utilities. Some of these occurrences have been correlated with upstream discharges of bromide‐containing wastes from coal‐fired power utilities, discharges of hydraulic fracturing wastewater, and other industrial sources. This article discusses this problem in terms of the chemistry of DBP formation when bromide is present, regulatory changes that have resulted in the increased use of bromide by industries, and the number of water utilities potentially affected by these discharges. The authors investigated this problem through a review of published and unpublished sources and through interviews with utility personnel and state regulators.

Simulation of plant flocculators can be accomplished by using jar testing equipment. Similar conditions should be maintained between laboratory and full-scale work. In this article several G curves for jar testing are presented that allow different small-scale geometries to be used. Power curves were also developed and correlated to power numbers available in the literature for large impellers. Subsequently, a procedure is presented for determining the full-scale G values.Many factors affect the chemical demand and the settling velocities of water treated by coagulation. Of those factors, the physical and mechanical parameters associated with rapid mix and flocculation are extremely important. The degree of mixing induced in a mixing vessel has traditionally been measured by the time of mixing [t) and the velocity gradient [G), as developed by Camp.

Alum recovery has recently gained more attention because many water utilities need to improve their sludge handling and disposal practices. As part of an overall sludge management program, alum recovery can reduce the amount of solids and allow for reuse of the recovered alum as a coagulant. It also has other potential uses such as phosphorus control at wastewater treatment plants.The city of Durham, N.C., performed full-scale testing of alum recovery utilizing the existing sand drying beds for sludge dewatering. The existing sand beds were undersized, but site constraints prevented construction of the necessary drying bed area to properly dewater the settled solids. Full-scale tests of alum recovery by acidification of the settled solids were conducted to (1) develop design criteria for full scale implementation, (2) test the full-scale dewatering of the solids remaining after alum recovery, (3) test the effectiveness of the recovered alum for reuse at the water treatment plant on a full scale, and (4) evaluate the use of recovered alum for phosphorus removal at the wastewater plant. BackgroundThe full-scale tests were conducted at the 22.mgd (83.ML/d) Williams Water Treatment Plant in Durham. Treatment processes at the plant include the use of alum (aluminum sulfate) for coagulation of turbidity and for color removal.