If you thought reverse osmosis was the one and only choice for potable water reuse, think again. Ozonation followed by biological activated carbon (ozone-BAC) is more suited to inland communities and may be better at removing chemicals of emerging concern (CECs).
Levels of a widely used class of industrial chemicals linked with cancer and other health problems — polyfluoroalkyl and perfluoroalkyl substances (PFASs) — exceed federally recommended safety levels in public drinking-water supplies for 6 million people in the United States, according to a new study led by researchers from the Harvard T.H. Chan School of Public Health and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).
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.
The City of Somersworth has a historical background dating back to the early 1900s when it became the first community to start using chlorine to disinfect it’s drinking water.
A potable water plant in Eastern Angelina County, Texas, serves over 2,000 rural customers.
The North Columbus Resource Facility recently completed a $12-million replacement of its settled water filtration, removing the existing Wheeler filters, their three-part media and 10-inch poured concrete underdrains, which were no longer efficient.
Historically, Lyon County Utilities, Nevada, applied 12.5% bulk sodium hypochlorite for disinfection at each of their well sites. Always looking to improve system efficiency, Lyon County staff reexamined on‐site hypochlorite generation to determine if the use of the 0.8% sodium hypochlorite solution could mitigate the challenges associated with dosing high strength sodium hypochlorite.
For drinking water treatment plants (DWTPs), the EPA’s Disinfection Byproduct Rule (DBP) is a way of life. Unfortunately, for many facilities the equipment and operations haven’t evolved with the regulation mandates, leaving facilities in a tough spot. For a DWTP in Douglas County, KS, its challenges with accurate TOC measurement and testing, along with expensive calibrations and extended downtime with its prior TOC analyzer led it to trialing the Hach QbD1200 TOC Analyzer. Read the full case study to learn more.
With 100 years of service history, Austin Water has seen enormous change in its 540 square miles of service area. Planning for the next 100 years has city and utility planners considering a diversity of sources, system resilience, and sustainability while being mindful of conservation goals. In the city’s newest water treatment plant, WTP4, Austin Water was able to combine those planning elements into a state‐of‐the‐art treatment plant. The plant, which is located on Lake Travis, is capable of treating 50 million gallons a day (MGD) with the ability to expand to 300 MGD.
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?
Examples of medicines and personal care products detected in water include antimicrobial materials found in toothpastes and hand soaps, fragrances, prescription medicines, bug sprays, and sunscreen. Concentrations of these substances detected in water are typically very small and are currently not regulated at the federal level in the U.S.
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.
A San Jose Water Quality Engineer said, "“I wasn’t convinced that PSI’s Monoclor™ chloramine dosing system would solve our problems after several failed attempts to improve residual, but with PSI offering a trial including installation, operation, and troubleshooting for three months, San Jose Water decided to invest the necessary resources to pilot this system.
Eastern Municipal Water District (EMWD) serves about 142,000 customers in Riverside County, CA. The EMWD service area is one of the largest for any water district in arid southern California. On the drinking water side, EMWD manages two water treatment plants and over 15 reservoirs. With 70% of the district’s water coming from the Metropolitan Water District with chloramine disinfection, EMWD has become reliant on chloramine disinfection to manage long transmission lines and longer detention times.
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).