Waste Water / Effluent Water
One of the most commonly measured constituents of wastewater is the biochemical oxygen demand, or BOD. Wastewater is composed of a variety of inorganic and organic substances. Organic substances refer to molecules that are based on carbon and include fecal matter as well as detergents, soaps, fats, greases and food particles (especially where garbage grinders are used).
These large organic molecules are easily decomposed by bacteria in the septic system. However, oxygen is required for this process of breaking large molecules into smaller molecules and eventually into carbon dioxide and water. The amount of oxygen required for this process is known as the biochemical oxygen demand or BOD. The Five-day BOD, or BOD5, is measured by the quantity of oxygen consumed by microorganisms during a five-day period, and is the most common measure of the amount of biodegradable organic material in, or strength of, sewage.
BOD has traditionally been used to measure of the strength of effluent released from conventional sewage treatment plants to surface waters or streams. This is because sewage high in BOD can deplete oxygen in receiving waters, causing fish kills and ecosystem changes. Based on criteria for surface water discharge, the secondary treatment standard for BOD has been set at 30 mg BOD/L (i.e. 30 mg of O2 are consumed per liter of water over 5 days to break down the waste).
Wastewater treatment effluent or discharge is the final product from a wastewater treatment plant. Because of the Federal Clean Water Act, the requirements for the treatment of the water is set on a plant-by-plant basis determined by the National Pollutant Discharge Elimination System (NPDES). The majority of effluent is discharged into a body of water, but it also has its uses.
Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.
Effluent, in engineering, is the stream exiting a chemical reactor.Effluent is defined by the United States Environmental Protection Agency as “wastewater – treated or untreated – that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters”. The Compact Oxford English Dictionary defines effluent as “liquid waste or sewage discharged into a river or the sea”.
Effluent in the artificial sense is in general considered to be water pollution, such as the outflow from a sewage treatment facility or the wastewater discharge from industrial facilities. An effluent sump pump, for instance, pumps waste from toilets installed below a main sewage line. In the context of waste water treatment plants, effluent that has been treated is sometimes called secondary effluent, or treated effluent. This cleaner effluent is then used to feed the bacteria in biofilters.
In the context of a thermal power station, the output of the cooling system may be referred to as the effluent cooling water, which is noticeably warmer than the environment. Effluent only refers to liquid discharge. In sugar beet processing, effluent is often settled in water tanks that allow the mud-contaminated water to settle. The mud sinks to the bottom, leaving the top section of water clear, free to be pumped back into the river or be reused in the process again.
The Mississippi River’s effluent of fresh water is so massive (7,000 to 20,000 m³/sec, or 200,000 to 700,000 ft³/sec) that a plume of fresh water is detectable by the naked eye from space, even as it rounds Florida and up to the coast of Georgia.
Effluent can have a variety of uses, although most effluent is dumped into rivers and large bodies of water it is also used for irrigation and industrial use as well. Effluent is also can be used to enhance wetlands and marshes which can attract more wildlife to the region and possibly create a recreational area. Spraying or injecting the discharge into the ground above a non potable aquifer and letting it seep down is a common way of routing the water for industrial use, but using the effluent directly from the plant for drinking water has been done in the United States on a very limited basis.