In the 1990s, the City of Wichita, KS, developed a water supply plan that included creating a sustainable water supply through the year 2050. The key component of the plan is recharging the large aquifer that lies under the region with 100 MGD of water from the Little Arkansas River.
Hendersonville Utility District (HUD) serves one of the most populous suburbs of Nashville, Tennessee.
Like many cities within the Dallas-Fort Worth metroplex, the City of Coppell experienced water quality challenges at different periods throughout the year. In particular, the City had difficulty maintaining adequate chloramine residuals at the 1.5 MG Southwestern elevated storage tank during the warmer summer months when outdoor watering was restricted to conserve water.
The Water Environment & Reuse Foundation introduces a “bundle of research” to help direct potable reuse and its practitioners reach full potential.
Originally built to treat 10 million gallons per day (MGD), the Quail Creek Water Treatment Plant in Washington County, Utah, now has an operational capacity of 60 MGD and a design capacity of 80 MGD.
For decades, a Winnipeg utility used a multiple point-chlorination process to treat raw water drawn from remote Shoal Lake. Concerns eventually arose about the potential presence of chlorine-resistant pathogens–Crytosporidium and Giardia–and residual disinfection byproducts, which coincided with encroaching development near the lake. The Clari-DAF system was selected and now removes 70 percent of the organics at the Winnipeg plant, which also improves filtration and extends the intervals between filter backwashes.
Ultrafiltration (UF) membranes have already gained worldwide acceptance in the treatment of drinking water for their removal of chlorine resistant pathogens such as cryptosporidium. Tertiary treatment with UF has been established, although with a lower level of knowledge and number of installations. This paper will discuss the performance of hollow fiber UF/MF membrane modules in treating tertiary effluent, and the subsequent performance of the downstream RO membranes.
Three Valleys Municipal Water District (Three Valleys) is one of 26 water agencies that comprise the Metropolitan Water District of Southern California (MWD). Three Valleys is the primary source of supplemental water for the Pomona, Walnut, and East San Gabriel Valleys.
The U.S. EPA's promulgation of the Stage 2 Disinfection By-Products Rule required the Public Works Department of Danvers, MA, to establish a Two-Phase upgrade of the plant’s treatment process in order to comply.
The 34 MGD Otay Water Treatment Plant in San Diego, California serves a population of approximately 200,000. It is a conventional treatment plant that uses coagulation, flocculation, sedimentation, filtration and disinfection. The plant receives raw water from two different sources — imported water from the Colorado River and runoff water from three local reservoirs.
As a country, we’ve come a long way toward providing clean air, water, and land — essential resources that support healthy, productive lives. But we have more work to do to make sure that every American has access to safe drinking water.
PFCs are turning up in source waters and news cycles, drawing both public and regulatory concern. How pervasive is this group of emerging contaminants — namely PFOS and PFOA — and how might the saga unfold for utilities?
Chatsworth Water Works Commission provides both water and wastewater services to the 5,000 residents of the cities of Chatsworth and Eton, GA.
What would happen if there was an emergency in the U.S. that caused radioactive material to contaminate drinking water supplies? What steps could your utilities and government take?
The removal of contaminants from public drinking water systems in the US is mandated by the Environmental Protection Agency’s (EPA) National Primary Drinking Water Regulations. These are legally enforceable standards that protect public health by limiting the levels of contaminants in drinking water. Similar regulations are managed by agencies worldwide to protect their citizens from drinking water contamination.
There are a plethora of drinking water contaminant removal technologies that public and private water systems use to comply with the EPA’s drinking water regulations. These include reverse osmosis, membrane, nanofiltration, ultrafiltration, chlorine disinfection, UV disinfection and Ozone-based disinfection practices.
The EPA’s list of drinking water contaminants is organized into six types of contaminants and lists each contaminant along with its Maximum Contaminant Level (MCL), some of the potential health effects from long-term exposure above the MCL and the probable source of the drinking water contaminant.
The six types of contaminants are microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals and radionuclides.
Examples of microbiological, organic contaminants are Cryptosporidium and Giardia lamblia. Both of these microorganic pathogens are found in human or animal fecal waste and cause gastrointestinal illness, such as diarrhea and vomiting.
A common disinfectant used in municipal drinking water treatment to disinfect microorganisms is chlorine. The EPA’s primary drinking water regulations require drinking water treatment plants to maintain a maximum disinfectant residual level (MDRL) for chlorine of 4.0 milligrams per liter (mg/L). Some of the detrimental health effects of chlorine above the MCL are eye irritation and stomach discomfort.
Similarly, byproducts from the chlorine-based disinfection methods used by public water systems to remove contaminants can be contaminants in their own right if not removed from the drinking water prior to it being released into the distribution system. Examples of disinfection byproducts include bromate, chlorite and total trihalomethanes (TTHMs). Not removed from drinking water, these disinfection byproducts can increase risk of cancer and cause central nervous system issues.
Chemical contamination of drinking water can be caused by inorganic chemicals such as arsenic, barium lead, mercury and cadmium or organic chemicals such as benzene, dichloroethane and other carbon-derived compounds. These chemicals get into source water through a variety of natural and industrial processes. Arsenic for example is present in source water through the erosion of natural deposits. Many of the chemical contaminants are derived from industrial wastewater such as discharges from petroleum refineries, steel or pulp mills or the corrosion of asbestos cement water mains or galvanized pipes.
Radium and uranium are examples of radionuclides. Radium 226 and Radium 228 must be removed to a level of 5 picocuries/liter (PCI/L) and Uranium to a level of 30 micrograms/liter (30 ug/L).