Hendersonville Utility District (HUD) serves one of the most populous suburbs of Nashville, Tennessee.
When the City of Midlothian, Texas, was ready to expand their water treatment plant to accommodate a growing population, they carefully considered and investigated their water disinfection options.
The Lariana Depur wastewater treatment plant in Fino Mornasco, Italy, treats wastewater from multiple textile manufacturers in the Como region, known as the heart of the textile industry. Since 1994, ozone has been used effectively as a polisher to remove the dark blue-purple color — the result of the dyes used in the textile dyeing and printing process — from the water.
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.
Upper Deerfield Township, NJ relies on groundwater from four wells measuring 120 to 160 feet deep. The water is treated at two treatment plants with a capacity of 2.2 MGD and then pumped out to the distribution system with approximately 750,000 gallons of storage. Since the deep groundwater is hard, operators add lime to the finished water to raise the pH to reduce hardness.
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).
WRT’s Z-88® Radium Removal treatment system was selected to remove high concentrations of radium in two treatment facilities for the City of Bridgeton, NJ. Both treatment facilities are now producing safer drinking water since the installation of the Z-88® Radium Removal treatment systems in 2009 and 2010.
In the fall of 2015, a small village on the border of Vermont in New York State, tested positive for Perfluorinated Compounds (PFCs), specifically Perfluorooctanoic Acid (PFOA), in the municipal drinking water. The influent levels of PFOA in the water were above 600 ng/L, and thus considered harmful to village residents. Realizing that PFOA was on the U.S. EPA Contaminant Candidate List, the Village solicited the services of engineering firm CT Male Associates to investigate treatment options and provide a treatment system.
The North Texas Metropolitan Water District began working to add ozone to its four interconnected water treatment facilities which operate as the Wylie Water Treatment Plant (WTP).
Reverse osmosis, or RO, is one of the finest technologies to purify water containing high total dissolved solids (TDS) levels of more than 500 ppm. Reverse osmosis plant exporters explain the technology as a separation technology where dissolved and invisible impurities in water are separated with the help of semi-permeable membrane or RO membrane that works under high pressure.
Well water from several locations in Ridgecrest, California area is high in arsenic, carbonates and pH. Due to the high levels of arsenic, some wells are not being used to supply municipal water to the city of Ridgecrest and were shutdown. Due to local demand, the feasibility of treating these wells to remove most of the arsenic before blending with water from other wells is being investigated.
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 design team for the intermediate ozone system at Buckingham Water Treatment Plant, Quebec, had limited space available for ozone contacting for the plant’s 1.3 – 7.4 MGD flow, so a standard fine bubble diffusion basin for ozone disinfection was not an option.
A single WRT Z-92® Uranium Removal treatment system was selected by the City of Grand Island, NE to remove high concentrations of uranium in three city wells. When the Z-92® Uranium Removal treatment system was installed in 2012, it was the largest uranium treatment facility in the nation. The high uranium in the raw water source is consistently being reduced to levels below the Maximum Contaminant Level (MCL).
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).