This category includes establishments primarily engaged in the collection and disposal of wastes transported through a sewer system. These private and public organizations usually treat the wastewater they collect before discharging it into the environment.
Sewage Treatment Facilities
Conventional sewerage treatment in the United States in the mid-2000s releases nearly 27 million tons of carbon dioxide into the air each year. Wastewater management has become big business now that federal amendments to the Safe Drinking Water Act (SDWA) of 1996 and the Clean Water Action Plan of 1998 put new life and new money into environmental protection. Concurrently, the increasing deregulation of public utilities and the privatization and public–private partnership development in wastewater treatment caused the industry to grow.
The Environmental Protection Agency (EPA) strengthened its legislation by imposing criminal and civil penalties on violators of the wastewater cleanup mandates. From Royal Caribbean Cruise Line's 1999 multi-million-dollar fine for dumping waste into the intracoastal waters to the $1.3 million fine and prison sentence for a Richmond, Virginia wastewater treatment executive, EPA continued to show that it meant business when it said "clean up."
In the mid-2000s the U.S. wastewater infrastructure was aging and often inadequate to handle the needs of growing populations. When it rained, many sewer systems were overwhelmed, and wastewater spilled directly into rivers and lakes. The EPA continued to implement regulations regarding the amount of sewerage that overflowed into the U.S. water supply. However, as municipalities worked to meet the EPA's expectations, all were looking at the huge price tag of repairing or replacing failing sewage infrastructures. At the same time, federal spending was declining, leaving a gap of billions of dollars between necessary and available funding.
Organizations in the wastewater industry are responsible for collecting wastewater from homes, businesses, and institutions, for treating wastewater to acceptable standards before discharging it into a waterway, and for disposing of residues called sludge. These activities entail building, operating, and maintaining a transport system and constructing and operating primary treatment facilities that remove or dilute toxins, synthetic debris, human waste, and other refuse.
Wastewater managers are expected to devise a system that transports wastewater as much as possible by gravity and that offers almost no threat of disruption in flow or service. Managers must also ensure that wastes do not seep into water supplies and that plant effluents are treated in a manner that does not significantly harm the environment. In accomplishing their duties, managers must comply with numerous state and federal regulations, financial restrictions, and political pressures. In addition, wastewater managers are often charged with developing resource recovery programs.
The majority of wastewater treatment plants consist of holding reservoirs that contain, chemically treat, and aerate wastewater until pollutants have settled out and the water can be safely jettisoned into a natural waterway. A few treatment plants use other systems. Approximately 300 municipal and industrial artificial marshland wastewater treatment systems were in operation across the country in the late 1990s. These marshes use plants and microorganisms to absorb and biodegrade the organics.
The two main sources of wastewater are residential and industrial. The large majority of residential wastewater is discharged into local sewer systems and treated by local utilities or publicly owned treatment works (POTWs). According to the EPA, in the mid-2000s there were about 16,000 POTWs across the nation, serving about 70 percent of the population, or 200 million people. The infrastructure also included an estimated 100,000 major pumping stations, 600,000 miles of sanitary sewers, 200,000 miles of storm sewers. POTWs treated more than 32 billion gallons of wastewater every day. POTWs range widely in size, with daily treatments capabilities from less than 100,000 gallons to more than 500 million gallons. About 80 percent of all POTWs treat less than one million gallons per day, but the remaining 20 percent of the largest systems serve 89 percent of the population.
The EPA estimated that 25 percent of U.S. residents still maintained on-site, or decentralized, disposal systems, including septic tanks, cesspools, and outhouses. The EPA does not regulate decentralized systems unless the systems process commercial or industrial wastewater or service more than 20 people.
Industrial waste is often pretreated at its source to remove hazardous wastes that require special handling. After being treated in surface impoundments or on-site treatment plants, the water is either discharged directly into the environment or released into local POTWs. About 80 percent of all industrial wastewater is eventually processed by POTWs. Industries that discharge waste into POTWs become subject to many of the same state and federal standards that regulate municipal wastewater facilities.
Most organizations that provide wastewater treatment services are publicly owned and operated as nonprofit entities. They may be established under a variety of organizational structures. A regional wastewater authority, for example, provides service either directly or through governmental entities such as cities, townships, water and sanitation districts, and counties. The regional authority may provide direct service and billing to individual customers, or it might offer wholesale service to several governmental entities that would in turn provide service and billing to local customers.
Large centralized treatment facilities, such as regional authorities, benefit from economies of scale. The drawback of this type of arrangement, however, is that centralized facilities often require pumping of wastewater over long distances. As a result, they tend to be less energy efficient and produce greater amounts of residue in a concentrated area than satellite (or local) treatment plants. Municipal special service districts, which represent a more localized wastewater organizational structure, avoid these drawbacks. Localized...