A large treatment plant includes several treatment processes that contribute to providing quality recycled water pursuant to the state of California Title 22 regulations. Major treatment processes include raw wastewater pumping, preliminary treatment, primary treatment, secondary treatment, tertiary treatment with Parkson DynaSand® filters, and disinfection.
Cooling towers and boilers consume the most fresh water in the industry, with industrial process waters carrying the balance. Power plants and refineries use more water volume for the cooling process than any other area of the facility. Mining and food and beverage industries consume higher volumes for their processes. Clean water may come from a range of sources, including clarified surface waters, groundwater or properly treated wastewater (reuse) sources.
The City of Rushville, Indiana had to remedy a consent order filed in 2007 for its untreated combined sewer overflow (CSO) discharges that were polluting the Flatrock River, a violation of the Clean Water Act. The city originally planned to install a 1 MGD stormwater storage tank, but was approached by Aqua-Aerobic representatives with a pilot test proposal utilizing a new technology.
Power plants and refineries around the world must manage and treat complex effluent waste streams from the Flue Gas Desulfurization (FGD) process. Flue gas is generated by the combustion process of fossil and fossil-derived fuels, such as coal, oils, and natural gas in power plants. Petrochemical refineries may generate flue gas from a number of different processes, including Catalytic Cracking, Steam Methane Reforming, and Heaters or Furnaces.
Filtration and separation technologies are the core of water treatment processes, and in many cases, they can be critical process bottlenecks.
Located about 78 miles (125 kilometers) west of Mexico City lies the municipality of Villa de Allende, home of Mexico’s largest potable water treatment plant. The Los Berros water treatment plant was constructed in 1980 by the National Water Commission (Conagua), an agency of the Mexican government that manages the nation’s drinking water and wastewater treatment. The plant provides 396.3 million gal/day (1.5 billion L/day) of water to the country’s capital city, equivalent to approximately 25 percent of the total water supply of the western hemisphere’s most populace metropolitan area.
Nutrient pollution is getting worse in many estuaries throughout the United States, especially those on the heavily populated East Coast.
The Baia Mare Aurul gold mine in North Western Romania suffered a historic catastrophe in January 2000, when its dam burst, streaming out 100,000 cubic meters of waste water, largely contaminated with cyanide, commonly used in the process of mining gold, into tributaries of the Tisza River, a major waterway in Hungary.
The cities of Littleton and Englewood, CO, just south of Denver, share a wastewater plant — the Littleton/Englewood advanced wastewater treatment (AWT) plant located in Englewood. The 7886 m3/hr (50-mgd) Littleton/Englewood AWT plant serves more than 300,000 residents in the Denver metropolitan area. The facility also receives sewage from 21 districts within a 75 square mile service area. Plant effluent is discharged to the Denver metro area’s major watershed, the South Platte River.
Arlington County’s Water Pollution Control Plant (WPCP) in South Arlington, VA, is located on 35 acres of land squeezed into a commercial/residential neighborhood less than a mile west of Ronald Reagan Washington National Airport. The facility treats flows from nearly all of Arlington. In addition, nearly 20 percent of the plant’s flow comes from neighboring localities such as Alexandria, Fairfax County, and Falls Church. Effluent from the plant is discharged into Four Mile Run to the south, which feeds into the Potomac River and, ultimately, the Chesapeake Bay.
In 2007, Greenville, SC-based Western Carolina Regional Sewer Authority (WCRSA) conducted a rigorous performance test on a new tertiary treatment technology to assess its ability to effectively remove nitrate-nitrogen (NO3-N) without using excess amounts of methanol at its Lower Reedy Wastewater Treatment Plant (WWTP).
As a result of China’s rapid economic development in recent years, the country has implemented more stringent environmental standards. Local environmental protection departments now require most urban wastewater treatment plants (WWTP) to apply strict enforcement measures to meet Class IA effluent discharge standards according to the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002).
Wastewater filtration is often part of the tertiary treatment process that involves the final removal of suspended particles from water that has passed through both the primary and secondary treatment phases and immediately precedes disinfection. As the water passes through the filter, residual suspended material and bacteria is trapped in the filter and are removed from the filtered water. Passage can be blocked by physical obstruction, biological action, adsorption, absorption or a combination of ways. Wastewater filtration is usually the final step in the solids removal process.
With regulations increasing around wastewater effluent, the use of ultrafiltration and microfiltration systems in further polishing effluent has grown. Sand or activated carbon filters can provide a media for bacterial decomposition of nutrients, converting nitrates into nitrogen gas. The rise of water reuse applications is also fueling the increasing use of filters during the final polishing stages of the wastewater treatment process.