Wastewater
Encyclopedia
Wastewater is any water
that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources.
Sewage is correctly the subset of wastewater that is contaminated with feces
or urine
, but is often used to mean any waste water. "Sewage
" includes domestic, municipal, or industrial liquid waste product
s disposed of, usually via a pipe
or sewer
or similar structure, sometimes in a cesspool emptier
.
The physical infrastructure, including pipes, pump
s, screens, channels etc. used to convey sewage from its origin to the point of eventual treatment or disposal is termed sewerage
.
material present in a natural waterway or in an industrial wastewater will be oxidized both by biochemical
(bacterial) or chemical processes. The result is that the oxygen content of the water will be decreased. Basically, the reaction for biochemical oxidation may be written as:
Oxygen consumption by reducing chemicals such as sulfides and nitrites is typified as follows:
Since all natural waterways contain bacteria and nutrients, almost any waste compounds introduced into such waterways will initiate biochemical reactions (such as shown above). Those biochemical reactions create what is measured in the laboratory as the Biochemical oxygen demand
(BOD). Such chemicals are also liable to be broken down using strong oxidizing agents and these chemical reactions create what is measured in the laboratory as the Chemical oxygen demand
(COD). Both the BOD and COD tests are a measure of the relative oxygen-depletion effect of a waste contaminant. Both have been widely adopted as a measure of pollution effect. The BOD test measures the oxygen demand of biodegradable
pollutants whereas the COD test measures the oxygen demand of oxidizable pollutants.
The so-called 5-day BOD measures the amount of oxygen consumed by biochemical oxidation of waste contaminants in a 5-day period. The total amount of oxygen consumed when the biochemical reaction is allowed to proceed to completion is called the Ultimate BOD. Because the Ultimate BOD is so time consuming, the 5-day BOD has been almost universally adopted as a measure of relative pollution effect.
There are also many different COD tests of which the 4-hour COD is probably the most common.
There is no generalized correlation between the 5-day BOD and the ultimate BOD. Similarly there is no generalized correlation between BOD and COD. It is possible to develop such correlations for specific waste contaminants in a specific waste water stream but such correlations cannot be generalized for use with any other waste contaminants or waste water streams. This is because the composition of any waste water stream is different. As an example an effluent consisting of a solution of simple sugar
s that might discharge from a confectionery
factory is likely to have organic components that degrade very quickly. In such a case, the 5 day BOD and the ultimate BOD would be very similar since there would be very little organic material left after 5 days. However a final effluent of a sewage treatment works serving a large industrialised area might have a discharge where the ultimate BOD was much greater than the 5 day BOD because much of the easily degraded material would have been removed in the sewage treatment process and many industrial processes discharge difficult to degrade organic molecules.
The laboratory test procedures for the determining the above oxygen demands are detailed in many standard texts. American versions include the "Standard Methods For the Examination Of Water and Wastewater"
s and runoff from streets is carried in storm drain
s. Access to either of these is typically through a manhole
. During high precipitation periods a sanitary sewer overflow
can occur, forcing untreated sewage to flow back into the environment. This can pose a serious threat to public health
and the surrounding environment.
Sewage may drain directly into major watershed
s with minimal or no treatment. When untreated, sewage can have serious impacts on the quality of an environment and on the health of people. Pathogen
s can cause a variety of illnesses. Some chemicals pose risks even at very low concentrations and can remain a threat for long periods of time because of bioaccumulation
in animal or human tissue.
(WWTPs) which may include physical, chemical and biological treatment processes. However, the use of septic tank
s and other On-Site Sewage Facilities (OSSF
) is widespread in rural areas, serving up to one quarter of the homes in the U.S. The most important aerobic treatment system is the activated sludge process, based on the maintenance and recirculation of a complex biomass composed by micro-organisms able to absorb and adsorb the organic matter carried in the wastewater. Anaerobic processes are widely applied in the treatment of industrial wastewaters and biological sludge. Some wastewater may be highly treated and reused as reclaimed water
. For some waste waters ecological approaches using reed bed
systems such as constructed wetland
s may be appropriate. Modern systems include tertiary treatment by micro filtration or synthetic membranes. After membrane filtration, the treated wastewater is indistinguishable from waters of natural origin of drinking quality. Nitrate
s can be removed from wastewater by microbial denitrification
, for which a small amount of methanol
is typically added to provide the bacteria with a source of carbon. Ozone Waste Water Treatment is also growing in popularity, and requires the use of an ozone generator, which decontaminates the water as Ozone bubbles percolate through the tank.
Disposal of wastewaters from an industrial plant is a difficult and costly problem. Most petroleum refineries, chemical and petrochemical plants have onsite facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the local and/or national regulations regarding disposal of wastewaters into community treatment plants or into rivers, lakes or oceans. Other Industrial processes that produce a lot of waste-waters such as paper and pulp production has created environmental concern leading to development of processes to recycle water use within plants before they have to be cleaned and disposed of.
, in industry (cooling towers), in artificial recharge of aquifers, in agriculture (70% of Israel's irrigated agriculture is based on highly purified wastewater) and in the rehabilitation of natural ecosystems (Florida's Everglades
).
, especially in low-income countries. Increasingly, agriculture
is using untreated wastewater for irrigation. Cities provide lucrative markets for fresh produce, so are attractive to farmers. However, because agriculture has to compete for increasingly scarce water resources with industry and municipal users, there is often no alternative for farmers but to use water polluted with urban waste directly to water their crops.
has developed guidelines for safe water use.
The International Water Management Institute
has worked in India, Pakistan, Vietnam, Ghana, Ethiopia, Mexico and other countries on various projects aimed at assessing and reducing risks of wastewater irrigation. They advocate a ‘multiple-barrier’ approach to wastewater use, where farmers are encouraged to adopt various risk-reducing behaviours. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in the sunlight, applying water carefully so it does not contaminate leaves likely to be eaten raw, cleaning vegetables with disinfectant or allowing fecal sludge used in farming to dry before being used as a human manure.
and Harbor Branch Oceanographic Institution, following the conclusions of the USDOE´s Aquatic Species Program
, use wastewater for breeding algae
. The wastewater from domestic and industrial sources contain rich organic compounds, which accelerate the growth of algae. This algae can be used to produce algal fuels
Algaewheel, based in Indianapolis, Indiana
, presented a proposal to build a new wastewater treatment facility in Cedar Lake, Indiana
that uses algae to treat municipal wastewater and uses the sludge
byproduct to produce biofuel.
" came from Old French
essouier = "to drain", which came from Latin
exaquāre. Their formal Latin antecedents are exaquāticum and exaquārium.
Commission Decision 93/481/EEC defines the information that Member States should provide the Commission on the state of implementation of the Directive.
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources.
Sewage is correctly the subset of wastewater that is contaminated with feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
or urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
, but is often used to mean any waste water. "Sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
" includes domestic, municipal, or industrial liquid waste product
Waste
Waste is unwanted or useless materials. In biology, waste is any of the many unwanted substances or toxins that are expelled from living organisms, metabolic waste; such as urea, sweat or feces. Litter is waste which has been disposed of improperly...
s disposed of, usually via a pipe
Pipeline transport
Pipeline transport is the transportation of goods through a pipe. Most commonly, liquids and gases are sent, but pneumatic tubes that transport solid capsules using compressed air are also used....
or sewer
Sanitary sewer
A sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
or similar structure, sometimes in a cesspool emptier
Cesspool emptier
A cesspool emptier is a type of specialized tank truck which can suck contaminated water out of hollows such as cesspools and sewage tanks and carry it to a disposal point....
.
The physical infrastructure, including pipes, pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
s, screens, channels etc. used to convey sewage from its origin to the point of eventual treatment or disposal is termed sewerage
Sanitary sewer
A sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
.
Origin
Wastewater or sewage can come from (text in brackets indicates likely inclusions or contaminants):- Human wasteHuman wasteHuman waste is a waste type usually used to refer to byproducts of digestion, such as feces and urine. Human waste is most often transported as sewage in waste water through sewerage systems...
(fæces, used toilet paperToilet paperToilet paper is a soft paper product used to maintain personal hygiene after human defecation or urination. However, it can also be used for other purposes such as blowing one's nose when one has a cold or absorbing common spills around the house, although paper towels are more used for the latter...
or wipes, urineUrineUrine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
, or other bodily fluids), also known as blackwaterBlackwater (waste)Blackwater is a term dating to at least the 1970s used to describe wastewater containing fecal matter and urine. It is also known as brown water, foul water, or sewage...
, usually from lavatories; - CesspitCesspitA cesspit, or cesspool is a pit, conservancy tank, or covered cistern, which can be used to dispose of urine and feces, and more generally of all sewage and refuse. It is a more antiquated solution than a sewer system. Traditionally, it was a deep cylindrical chamber dug into the earth, having...
leakage; - Septic tankSeptic tankA septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations...
discharge; - Sewage treatmentSewage treatmentSewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
plant discharge; - Washing water (personal, clothes, floors, dishes, etc.), also known as greywaterGreywaterGreywater is wastewater generated from domestic activities such as laundry, dishwashing, and bathing, which can be recycled on-site for uses such as landscape irrigation and constructed wetlands...
or sullage; - Rainfall collected on roofs, yards, hard-standings, etc. (generally clean with traces of oilOilAn oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
s and fuelFuelFuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
); - GroundwaterGroundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
infiltrated into sewage; - Surplus manufactured liquids from domestic sources (drinks, cooking oil, pesticidePesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s, lubricating oilLubricantA lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
, paintPaintPaint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
, cleaning liquids, etc.); - Urban rainfall runoff from roadRoadA road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
s, carparks, roofs, sidewalks, or pavements (contains oils, animal fæces, litterLitterLitter consists of waste products such as containers, papers, wrappers or faeces which have been disposed of without consent. Litter can also be used as a verb...
, fuel or rubberRubberNatural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
residues, metalMetalA metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s from vehicle exhaustsExhaust gasExhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle.It often disperses...
, etc.); - SeawaterSeawaterSeawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
ingress (high volumes of salt and micro-biota); - Direct ingress of riverRiverA river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
water (high volumes of micro-biota); - Direct ingress of manmade liquids (illegal disposal of pesticides, used oils, etc.);
- HighwayHighwayA highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...
drainage (oil, de-icing agents, rubber residues); - StormStormA storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
drains (almost anything, including cars, shopping trolleys, trees, cattle, etc.); - BlackwaterBlackwater (waste)Blackwater is a term dating to at least the 1970s used to describe wastewater containing fecal matter and urine. It is also known as brown water, foul water, or sewage...
(surface water contaminated by sewage); - Industrial waste
- industrialIndustryIndustry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...
site drainage (silt, sand, alkali, oil, chemical residues);- Industrial cooling waters (biocides, heat, slimes, silt);
- Industrial process waters;
- Organic or bio-degradable waste, including waste from abattoirs, creameriesCreameryIn a dairy, the creamery is the location of cream processing. Cream is separated from whole milk; pasteurization is done to the skimmed milk and cream separately. Whole milk for sale has had some cream returned to the skimmed milk....
, and ice creamIce creamIce cream is a frozen dessert usually made from dairy products, such as milk and cream, and often combined with fruits or other ingredients and flavours. Most varieties contain sugar, although some are made with other sweeteners...
manufacture; - Organic or non bio-degradable/difficult-to-treat waste (pharmaceutical or pesticidePesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
manufacturing); - extreme pHPHIn chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
waste (from acidAcidAn acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
/alkaliAlkaliIn chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
manufacturing, metal plating); - Toxic waste (metal platingPlatingPlating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years, but it is also critical for modern technology...
, cyanideCyanideA cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....
production, pesticidePesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
manufacturing, etc.); - Solids and EmulsionEmulsionAn emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...
s (paperPaperPaper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
manufacturing, foodstuffs, lubricating and hydraulic oilOilAn oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
manufacturing, etc.); - agriculturalAgricultureAgriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
drainage, direct and diffuse.
Wastewater constituents
The composition of wastewater varies widely. This is a partial list of what it may contain:- Water ( > 95%) which is often added during flushingFlush toiletA flush toilet is a toilet that disposes of human waste by using water to flush it through a drainpipe to another location. Flushing mechanisms are found more often on western toilets , but many squat toilets also are made for automated flushing...
to carry waste down a drain; - Pathogens such as bacteria, virusVirusA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, prionPrionA prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...
s and parasitic worms; - Non-pathogenic bacteriaBacteriaBacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
; - Organic particles such as fecesFecesFeces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
, hairHairHair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
s, foodFoodFood is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
, vomit, paper fibers, plant material, humus, etc.; - Soluble organic material such as ureaUreaUrea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
, fruit sugars, soluble proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, drugsMedicationA pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
, pharmaceuticals, etc.; - Inorganic particles such as sandSandSand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
, grit, metal particles, ceramicCeramicA ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
s, etc.; - Soluble inorganic material such as ammoniaAmmoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
, road-salt, sea-salt, cyanideCyanideA cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....
, hydrogen sulfideHydrogen sulfideHydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
, thiocyanateThiocyanateThiocyanate is the anion [SCN]−. It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called thiocyanates...
s, thiosulfateThiosulfateThiosulfate is an oxyanion of sulfur. The prefix thio indicates that thiosulfate ion is a sulfate ion with one oxygen replaced by a sulfur. Thiosulfate occurs naturally and is produced by certain biochemical processes...
s, etc.; - Animals such as protozoaProtozoaProtozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
, insectInsectInsects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, arthropodArthropodAn arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, small fishFishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, etc.; - Macro-solids such as sanitary napkinSanitary napkinA sanitary napkin, sanitary towel, sanitary pad, menstrual pad, maxi pad, or pad is an absorbent item worn by a woman while she is menstruating, recovering from vaginal surgery, for lochia , abortion, or any other situation where it is necessary to absorb a flow of blood from a woman's vagina.These...
s, nappies/diapersDiaperA nappy or a diaper is a kind of pant that allows one to defecate or urinate on oneself discreetly. When diapers become soiled, they require changing; this process is often performed by a second person such as a parent or caregiver...
, condomCondomA condom is a barrier device most commonly used during sexual intercourse to reduce the probability of pregnancy and spreading sexually transmitted diseases . It is put on a man's erect penis and physically blocks ejaculated semen from entering the body of a sexual partner...
s, needleHypodermic needleA hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...
s, children's toys, dead animals or plants, etc.; - Gases such as hydrogen sulfideHydrogen sulfideHydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
, carbon dioxideCarbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, methaneMethaneMethane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
, etc.; - EmulsionEmulsionAn emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...
s such as paintPaintPaint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
s, adhesiveAdhesiveAn adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
s, mayonnaiseMayonnaiseMayonnaise, , often abbreviated as mayo, is a sauce. It is a stable emulsion of oil, egg yolk and either vinegar or lemon juice, with many options for embellishment with other herbs and spices. Lecithin in the egg yolk is the emulsifier. Mayonnaise varies in color but is often white, cream, or pale...
, hairHairHair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
colorants, emulsified oils, etc.; - Toxins such as pesticidePesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s, poisonPoisonIn the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
s, herbicideHerbicideHerbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
s, etc. - Pharmaceuticals and other hormones.
Wastewater quality indicators
Any oxidizableRedox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
material present in a natural waterway or in an industrial wastewater will be oxidized both by biochemical
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
(bacterial) or chemical processes. The result is that the oxygen content of the water will be decreased. Basically, the reaction for biochemical oxidation may be written as:
- Oxidizable material + bacteria + nutrient + O2 → CO2 + H2O + oxidized inorganicsInorganic chemistryInorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...
such as NO3 or SO4
Oxygen consumption by reducing chemicals such as sulfides and nitrites is typified as follows:
- S-- + 2 O2 → SO4--
- NO2- + ½ O2 → NO3-
Since all natural waterways contain bacteria and nutrients, almost any waste compounds introduced into such waterways will initiate biochemical reactions (such as shown above). Those biochemical reactions create what is measured in the laboratory as the Biochemical oxygen demand
Biochemical oxygen demand
Biochemical oxygen demand or B.O.D. is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for...
(BOD). Such chemicals are also liable to be broken down using strong oxidizing agents and these chemical reactions create what is measured in the laboratory as the Chemical oxygen demand
Chemical oxygen demand
In environmental chemistry, the chemical oxygen demand test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water or wastewater, making COD a useful measure of water quality...
(COD). Both the BOD and COD tests are a measure of the relative oxygen-depletion effect of a waste contaminant. Both have been widely adopted as a measure of pollution effect. The BOD test measures the oxygen demand of biodegradable
Biodegradation
Biodegradation or biotic degradation or biotic decomposition is the chemical dissolution of materials by bacteria or other biological means...
pollutants whereas the COD test measures the oxygen demand of oxidizable pollutants.
The so-called 5-day BOD measures the amount of oxygen consumed by biochemical oxidation of waste contaminants in a 5-day period. The total amount of oxygen consumed when the biochemical reaction is allowed to proceed to completion is called the Ultimate BOD. Because the Ultimate BOD is so time consuming, the 5-day BOD has been almost universally adopted as a measure of relative pollution effect.
There are also many different COD tests of which the 4-hour COD is probably the most common.
There is no generalized correlation between the 5-day BOD and the ultimate BOD. Similarly there is no generalized correlation between BOD and COD. It is possible to develop such correlations for specific waste contaminants in a specific waste water stream but such correlations cannot be generalized for use with any other waste contaminants or waste water streams. This is because the composition of any waste water stream is different. As an example an effluent consisting of a solution of simple sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s that might discharge from a confectionery
Confectionery
Confectionery is the set of food items that are rich in sugar, any one or type of which is called a confection. Modern usage may include substances rich in artificial sweeteners as well...
factory is likely to have organic components that degrade very quickly. In such a case, the 5 day BOD and the ultimate BOD would be very similar since there would be very little organic material left after 5 days. However a final effluent of a sewage treatment works serving a large industrialised area might have a discharge where the ultimate BOD was much greater than the 5 day BOD because much of the easily degraded material would have been removed in the sewage treatment process and many industrial processes discharge difficult to degrade organic molecules.
The laboratory test procedures for the determining the above oxygen demands are detailed in many standard texts. American versions include the "Standard Methods For the Examination Of Water and Wastewater"
Sewage disposal
In some urban areas, sewage is carried separately in sanitary sewerSanitary sewer
A sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
s and runoff from streets is carried in storm drain
Storm drain
A storm drain, storm sewer , stormwater drain or drainage well system or simply a drain or drain system is designed to drain excess rain and ground water from paved streets, parking lots, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems...
s. Access to either of these is typically through a manhole
Manhole
A manhole is an opening used to gain access to sewers or other underground structures, usually for maintenance.Manhole may also refer to:* Manhole , a metal band from Los Angeles* The Manhole, a computer game...
. During high precipitation periods a sanitary sewer overflow
Sanitary sewer overflow
Sanitary sewer overflow is a condition whereby untreated sewage is discharged into the environment prior to reaching treatment facilities thereby escaping wastewater treatment. When caused by rainfall it is also known as wet weather overflow. It is primarily meaningful in developed countries,...
can occur, forcing untreated sewage to flow back into the environment. This can pose a serious threat to public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
and the surrounding environment.
Sewage may drain directly into major watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
s with minimal or no treatment. When untreated, sewage can have serious impacts on the quality of an environment and on the health of people. Pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s can cause a variety of illnesses. Some chemicals pose risks even at very low concentrations and can remain a threat for long periods of time because of bioaccumulation
Bioaccumulation
Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost...
in animal or human tissue.
Treatment
There are numerous processes that can be used to clean up waste waters depending on the type and extent of contamination. Most wastewater is treated in industrial-scale wastewater treatment plantsSewage treatment
Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
(WWTPs) which may include physical, chemical and biological treatment processes. However, the use of septic tank
Septic tank
A septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations...
s and other On-Site Sewage Facilities (OSSF
OSSF
On Site Sewage Facilities are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater....
) is widespread in rural areas, serving up to one quarter of the homes in the U.S. The most important aerobic treatment system is the activated sludge process, based on the maintenance and recirculation of a complex biomass composed by micro-organisms able to absorb and adsorb the organic matter carried in the wastewater. Anaerobic processes are widely applied in the treatment of industrial wastewaters and biological sludge. Some wastewater may be highly treated and reused as reclaimed water
Reclaimed water
Reclaimed water or recycled water, is former wastewater that is treated to remove solids and certain impurities, and used in sustainable landscaping irrigation or to recharge groundwater aquifers...
. For some waste waters ecological approaches using reed bed
Reed bed
Reed beds are natural habitats found in floodplains, waterlogged depressions andestuaries. Reed beds are part of a succession from young reed colonising open water or wet ground through a gradation of increasingly dry ground...
systems such as constructed wetland
Constructed wetland
A constructed wetland or wetpark is an artificial wetland, marsh or swamp created as a new or restored habitat for native and migratory wildlife, for anthropogenic discharge such as wastewater, stormwater runoff, or sewage treatment, for land reclamation after mining, refineries, or other...
s may be appropriate. Modern systems include tertiary treatment by micro filtration or synthetic membranes. After membrane filtration, the treated wastewater is indistinguishable from waters of natural origin of drinking quality. Nitrate
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
s can be removed from wastewater by microbial denitrification
Denitrification
Denitrification is a microbially facilitated process of nitrate reduction that may ultimately produce molecular nitrogen through a series of intermediate gaseous nitrogen oxide products....
, for which a small amount of methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
is typically added to provide the bacteria with a source of carbon. Ozone Waste Water Treatment is also growing in popularity, and requires the use of an ozone generator, which decontaminates the water as Ozone bubbles percolate through the tank.
Disposal of wastewaters from an industrial plant is a difficult and costly problem. Most petroleum refineries, chemical and petrochemical plants have onsite facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the local and/or national regulations regarding disposal of wastewaters into community treatment plants or into rivers, lakes or oceans. Other Industrial processes that produce a lot of waste-waters such as paper and pulp production has created environmental concern leading to development of processes to recycle water use within plants before they have to be cleaned and disposed of.
Reuse
Treated wastewater can be reused as drinking waterDrinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
, in industry (cooling towers), in artificial recharge of aquifers, in agriculture (70% of Israel's irrigated agriculture is based on highly purified wastewater) and in the rehabilitation of natural ecosystems (Florida's Everglades
Everglades
The Everglades are subtropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee...
).
Use of untreated wastewater by agriculture
Around 90% of wastewater produced globally remains untreated, causing widespread water pollutionPollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, especially in low-income countries. Increasingly, agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
is using untreated wastewater for irrigation. Cities provide lucrative markets for fresh produce, so are attractive to farmers. However, because agriculture has to compete for increasingly scarce water resources with industry and municipal users, there is often no alternative for farmers but to use water polluted with urban waste directly to water their crops.
Health hazards of polluted irrigation water
There can be significant health hazards related to using the water in this way. Wastewater from cities can contain a mixture of chemical and biological pollutants. In low-income countries, there are often high levels of pathogens from excreta, while in emerging nations, where industrial development is outpacing environmental regulation, there are increasing risks from inorganic and organic chemicals. The World Health OrganizationWorld Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
has developed guidelines for safe water use.
The International Water Management Institute
International Water Management Institute
The International Water Management Institute is a non-profit research organisation with headquarters in Colombo, Sri Lanka, and offices across Africa and Asia...
has worked in India, Pakistan, Vietnam, Ghana, Ethiopia, Mexico and other countries on various projects aimed at assessing and reducing risks of wastewater irrigation. They advocate a ‘multiple-barrier’ approach to wastewater use, where farmers are encouraged to adopt various risk-reducing behaviours. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in the sunlight, applying water carefully so it does not contaminate leaves likely to be eaten raw, cleaning vegetables with disinfectant or allowing fecal sludge used in farming to dry before being used as a human manure.
Algal fuel
Woods Hole Oceanographic InstitutionWoods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution is a private, nonprofit research and higher education facility dedicated to the study of all aspects of marine science and engineering and to the education of marine researchers. Established in 1930, it is the largest independent oceanographic research...
and Harbor Branch Oceanographic Institution, following the conclusions of the USDOE´s Aquatic Species Program
Aquatic Species Program
The Aquatic Species Program was a research program in the United States launched in 1978 by President Jimmy Carter and was funded by the United States Department of Energy, which over the course of nearly two decades looked into the production of energy using algae. Initially, the funding of the...
, use wastewater for breeding algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
. The wastewater from domestic and industrial sources contain rich organic compounds, which accelerate the growth of algae. This algae can be used to produce algal fuels
Algaewheel, based in Indianapolis, Indiana
Indianapolis, Indiana
Indianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County, Indiana. As of the 2010 United States Census, the city's population is 839,489. It is by far Indiana's largest city and, as of the 2010 U.S...
, presented a proposal to build a new wastewater treatment facility in Cedar Lake, Indiana
Cedar Lake, Indiana
-Demographics:As of the census of 2000, there were 9,279 people, 3,394 households, and 2,450 families residing in the town. The population density was 1,366.3 people per square mile . There were 3,681 housing units at an average density of 542.0 per square mile...
that uses algae to treat municipal wastewater and uses the sludge
Sludge
Sludge refers to the residual, semi-solid material left from industrial wastewater, or sewage treatment processes. It can also refer to the settled suspension obtained from conventional drinking water treatment, and numerous other industrial processes...
byproduct to produce biofuel.
Etymology
The words "sewage" and "sewerSanitary sewer
A sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
" came from Old French
Old French
Old French was the Romance dialect continuum spoken in territories that span roughly the northern half of modern France and parts of modern Belgium and Switzerland from the 9th century to the 14th century...
essouier = "to drain", which came from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
exaquāre. Their formal Latin antecedents are exaquāticum and exaquārium.
European Union
Council Directive 91/271/EEC on Urban Waste Water Treatment was adopted on 21 May 1991, amended by the Commission Directive 98/15/EC.Commission Decision 93/481/EEC defines the information that Member States should provide the Commission on the state of implementation of the Directive.
See also
- APHA colorAPHA colorAPHA color is a color standard named for the APHA and defined by ASTM D1209. It was originally intended to describe the color of waste water, but its usage has expanded to include other industrial applications....
- ATP TestATP testThe ATP test is a process of rapidly measuring actively growing microorganisms through detection of adenosine triphosphate, or ATP.-ATP testing method:...
- Directive on Urban Waste Water Treatment in European Union
- Ecological sanitationEcological sanitationEcological sanitation, also known as ecosan or eco-san, are terms coined to describe a form of sanitation that usually involves urine diversion and the recycling of water and nutrients contained within human wastes back into the local environment....
- Industrial water treatmentIndustrial water treatmentIndustrial Water Treatment can be classified into the following categories:* Boiler water treatment* Cooling water treatment* Wastewater treatment...
- List of waste types
- List of waste water treatment technologies
- Pt/Co scalePt/Co scaleThe Platinum-Cobalt Scale is a color scale that was introduced in 1892 by chemist Allen Hazen . The index was developed as a way to evaluate pollution levels in waste water. It has since expanded to a common method of comparison of the intensity of yellow-tinted samples...
- Rain gardenRain gardenA rain garden is a planted depression that allows rainwater runoff from impervious urban areas like roofs, driveways, walkways, parking lots, and compacted lawn areas the opportunity to be absorbed...
s - SanitationSanitationSanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Hazards can be either physical, microbiological, biological or chemical agents of disease. Wastes that can cause health problems are human and animal feces, solid wastes, domestic...
- Septic tankSeptic tankA septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations...
- Sewage treatmentSewage treatmentSewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
- Sewer
- SewerageSanitary sewerA sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
- The Environmental InstituteThe Environmental InstituteThe Environmental Institute is a non-profit organization devoted exclusively to building and managing Integrated Biosystems that purify sewagewater in urban areas and for small farms and agro-industries in South America...
- Waste managementWaste managementWaste management is the collection, transport, processing or disposal,managing and monitoring of waste materials. The term usually relates to materials produced by human activity, and the process is generally undertaken to reduce their effect on health, the environment or aesthetics...
- Water managementWater managementWater management is the activity of planning, developing, distributing and managing the optimum use of water resources. In an ideal world. water management planning has regard to all the competing demands for water and seeks to allocate water on an equitable basis to satisfy all uses and demands...
- Water pollutionWater pollutionWater pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
- Water resourcesWater resourcesWater resources are sources of water that are useful or potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. Virtually all of these human uses require fresh water....
- Water treatmentWater treatmentWater treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses. The goal of all water treatment process is to remove existing contaminants in the water, or reduce the...