'Sewage treatment' is the process that removes the majority of the contaminants from waste-water or sewage and produces both a liquid effluent suitable for disposal to the natural environment and a sludge. To be effective, sewage must be conveyed to a treatment plant by appropriate pipes and infrastructure and the process itself must be subject to regulation and controls. Other wastewaters require often different and sometimes specialised treatment methods. Sewage is domestic, municipal, or industrial liquid waste products. ... See also oil sludge for automobile engine failures Sludge is a solid waste extracted in the process of sewage treatment. ... Sewage collection and disposal Collection Wastewater collection systems consist of buried pipelines which convey the wastewater by gravity to the treatment plant. ... Sewage disposal regulation and administration Regulation USA Sewer systems in the United States are regulated by multiple agencies on the local, state, and federal levels. ...

Description

Sewage is the liquid waste from toilets, baths, showers, kitchens, etc. that is disposed of via sewers. In many areas sewage also includes some liquid waste from industry and commerce. In the UK, the waste from toilets is termed foul waste, the waste from items such as basins, baths, kitchens is termed sullage water, and the industrial and commercial waste is termed trade waste. Flush toilet A toilet is a where i take a dump not in my pants primarily intended for the disposal of bodily wastes such as urine and feces. ... The Palladian-style Pulteney Bridge and the weir at Bath. ... A shower used for bathing A shower is any of a number of things: Look up shower in Wiktionary, the free dictionary. ... A kitchen is a room used for food preparation. ... Sewers transport wastewater from buildings to treatment facilities. ...

The division of household water drains into greywater and blackwater is becoming more common in the developed world, with greywater being permitted to be used for watering plants or recycled for flushing toilets. Much sewage also includes some surface water from roofs or hard-standing areas. Municipal wastewater therefore includes residential, commercial, and industrial liquid waste discharges, and may include stormwater runoff. Greywater is water generated by household processes such as washing dishes, laundry and bathing. ... Blackwater (waste) is a relatively recent term used to describe water containing Feacal matter and Urine: its is also known as foul water, or as sewage. ... Storm water is a term used by engineers to describe precipitation. ...

Sewerage systems that transport liquid waste discharges and stormwater together to a common treatment facility are called combined sewer systems. The construction of combined sewers is a less common practice in the U.S. and Canada than in the past and is no longer accepted within Building Regulations in the UK and other European countries. Instead, liquid waste and stormwater are collected and conveyed in separate sewer systems, referred to as sanitary sewers and storm sewers in the U.S. and as foul sewers and surface water sewers in the UK. Overflows from foul sewers designed to relieve pressure from heavy rainfall are termed storm sewers or combined sewer overflows. World map showing location of Europe When considered a continent, Europe is the worlds second-smallest continent in terms of area, with an area of 10,600,000 km² (4,140,625 square miles), making it larger than Australia only. ...

As rainfall runs over the surface of roofs and the ground, it may pick up various contaminants including soil particles (sediment), heavy metals, organic compounds, animal waste, and oil and grease. Some jurisdictions require stormwater to receive some level of treatment before being discharged to the environment. Examples of treatment processes used for stormwater include sedimentation basins, wetlands, and vortex separators (to remove coarse solids). For the heavy metal band see Soil (band) Soil is unconsolidated rock particle that lies on the surface of the earth, intermingled, perhaps, with organic matter from plant decay. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ... For other meanings, see heavy metal The term heavy metal may have various more general or more specific meanings. ... Organic has several meanings and related topics. ... Oil is a generic term for organic liquids that are not miscible with water. ... The word grease can mean:- A type of industrial lubricant: see grease (lubricant). ... In law, jurisdiction refers to the aspect of a any unique legal authority as being localized within boundaries. ... A constructed wetland is an artificial marsh or swamp, created for human use, such as wastewater or sewage treatment, as habitat to attract wildlife, or for land reclamation after mining or other disturbance. ...

The conventional sewage treatment process typically involves the following three stages:

1. Primary Treatment - to settle out solids
2. Secondary treatment - to remove the dissolved and emulsified components
3. Tertiary treatment - to make the effluent fit to be received in the environment.

The site where the process is conducted is called a sewage treatment plant. The flow scheme of a sewage treatment plant is generally the same for all countries:

• Mechanical treatment;

Influx

Removal of large objects

Removal of sand

Pre-precipitation

• Biological treatment;

High-charged and low-charged purification systems

Oxidation bed (oxidizing bed)

Aerated systems

Post precipitation

Effluent

• Chemical treatment (this step is not always used).

Primary treatment

Primary treatment is to reduce oils, grease, fats, sand, grit, and coarse (settleable) solids. This step is done entirely with machinery, hence the name mechanical treatment. Patterns in the sand Sand is an example of a class of materials called granular matter. ...

Influx and removal of large objects

In the mechanical treatment, the influx of sewage water is strained to remove all large objects that are deposited in the sewer system, such as condoms, sanitary towels (sanitary napkins) or tampons, cans, fruit, etc. This is most commonly done using a manual or automated mechanically raked screen. This type of waste is removed because it can damage the sensitive equipment in the sewage treatment plant. A sanitary towel (U.K.) or sanitary napkin (U.S.) is an absorbent piece of material worn by a woman while she is menstruating, to absorb the flow of blood from the vagina. ... A tampon with an applicator. ...

Sand and Grit removal

This stage typically includes a sand or grit channel where the velocity of the incoming wastewater is carefully controlled to allow sand grit and stones to settle but still maintain the majority of the organic material within the flow. This equipment is called a detritor or sand catcher. Sand grit and stones need to be removed early in the process to avoid damage to pumps and other equipment in the remaining treatment stages. Sometimes there is a sand washer followed by a conveyor that transports the sand to a container for disposal. The contents from the sand catcher may be fed into the incinerated in a sludge processing plant but in many cases the sand and grit is sent to a land-fill Manual pump used to obtain water A pump is a mechanical device used to move liquids or gases. ...

Screening or maceration

The grit free liquid is then passed through fixed or rotating screens to remove floating and larger material such as rags. Screenings are collected and may be returned to the sludge treatment plant or may be disposed of off site by landfilling or incineration. Maceration, in which solids are cut into small particles through the use of rotating knife edges mounted on a revolving cylinder, is used in plants that are able to process this particulate waste. Macerators are, however, more expensive to maintain and are less reliable than physical screens. Landfill is a waste disposal site for the deposit of the waste onto or into land (i. ...

Sedimentation

Primary sedimentation tank at a rural treatment plant

In almost all plants there is a sedimentation stage where the sewage is allowed to pass through large circular or rectangular tanks. The tanks are large enough that faecal solids can settle and floating material such as grease and plastics can rise to the surface and be skimmed off. The main purpose of the primary stage is to produce a generally homogeneous liquid capable of being treated biologically and a sludge that can be separately treated or processed. Primary settlement tanks are usually equipped with mechanically driven scrapers that continually drive the collected sludge towards a hopper in the base of the tank from where it can be pumped to further sludge treatment stages. Download high resolution version (1296x972, 566 KB)sewage treatment primary sedimentation tank File links The following pages link to this file: Sewage treatment Categories: GFDL images ... Download high resolution version (1296x972, 566 KB)sewage treatment primary sedimentation tank File links The following pages link to this file: Sewage treatment Categories: GFDL images ... Rabbit feces are usually 0. ... Plastic is a term that covers a range of synthetic or semisynthetic polymerization products. ... The word hopper has these meanings:- A wide bin-like entry to feed large bulks of solid matter into a machine. ...

Secondary treatment

The second phase of sewage treatment is the biological treatment, which is eliminating dissolved organic contaminants (feces and urine). Bacteria eliminate the wastes by eating the contaminants.

Secondary treatment is designed to substantially degrade the biological content of the sewage. The majority of municipal and industrial plants treat the settled sewage liquor using aerobic biological processes. For this to be effective, the biota require both oxygen and a substrate on which to live. There are number of ways in which this is done. In all these methods, the bacteria and protozoa consume biodegradable soluble organic contaminants (e.g. sugars, fats, organic short-chain carbon molecules, etc.) and bind much of the less soluble fractions into floc particles. Secondary treatment systems are classified as fixed film or suspended growth. In fixed film systems - such as roughing filters - the biomass grows on media and the sewage passes over its surface. In suspended growth systems - such as activated sludge - the biomass is well mixed with the sewage. Typically, fixed film systems require smaller footprints than for an equivalent suspended growth system; however, suspended growth systems are more able to cope with shocks in biological loading. Aerobic is an adjective that means requiring air (where air usually means oxygen). ... Biota can refer to several things: The plant and animal life of a region; see biota (ecology) A municipality in Zaragoza, Aragon, Spain; see Biota (municipality) A superdomain in taxonomy; see Biota (taxonomy) Biota Holdings, the Australian biotech company This is a disambiguation page — a navigational aid which lists other... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... The word substrate can mean the following: In biochemistry, a substrate is a molecule which is acted upon by an enzyme. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Protozoa (in Greek protos = first and zoon = animal) are single-celled eukaryotes (organisms with nuclei) that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ... Biodegradation is the decomposition of organic material by microorganisms. ... A sugar is a carbohydrate which is sweet to taste. ... Look up fat in Wiktionary, the free dictionary. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... The introduction of this article does not provide enough context for readers unfamiliar with the subject. ...

Roughing Filters

Roughing filters are intended to treat particularly strong or variable organic loads, typically industrial. They are typically tall, circular filters filled with open synthetic filter media to which sewage is applied at a relatively high rate. The design of the filters allows high hydraulic loading and a high flow-through of air. On larger installations, air is forced through the media using blowers. The resultant liquor is usually within the normal range for conventional treatment processes.

Activated sludge

Activated sludge plants use a variety of mechanisms and processes to use dissolved oxygen to generate a biological floc that substantially removes organic material. It also traps particulate material and can, under ideal conditions, convert ammonia to nitrite and nitrate and ultimately to nitrogen gas, (see also denitrification). Activated sludge is a process in sewage treatment in which air or oxygen is forced into sewage liquor to develop a biological floc which reduces the organic content of the sewage. ... Ammonia is a compound of nitrogen and hydrogen with the formula NH3. ... Definition The nitrite ion is NO2-. A nitrite compound is one that contains this group, either an ionic compound, or an analogous covalent one. ... this is a negative ion,NO3- Discussion In inorganic chemistry, nitrates are the salts of nitric acid. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Denitrification is the process of reducing nitrate, a form of nitrogen available for consumption by many groups of organisms, into gaseous nitrogen, which is far less accessible to life forms but makes up the bulk of our atmosphere. ...

Filter Beds (Oxidising beds)

Trickling filter bed using plastic media

In older plants and plants receiving more variable loads, trickling filter beds are used where the settled sewage liquor is spread onto the surface of a deep bed made up of coke (carbonised coal), rocks or specially fabricated plastic media with high surface areas. The liquor is distributed through perforated rotating arms radiating from a central pivot. The distributed liquor trickles through this bed and is collected in drains at the base. These drains also provide a source of air which percolates up through the bed, keeping it aerobic. Biological film comprising of bacteria, protozoa and fungi forms on all the available surfaces and this provides the required biological treatment capability to effect the reduction in organic content. Download high resolution version (1296x972, 664 KB)Sewage Treatment trickling filter bed - small rural treatment plant Author: User:Velela. ... Download high resolution version (1296x972, 664 KB)Sewage Treatment trickling filter bed - small rural treatment plant Author: User:Velela. ... Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal from which the volatile constituents (including water, coal-gas and coal-tar) are driven off by baking in an airless oven at temperatures as high as 1,000 degrees Celsius so that the fixed carbon and... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ...

Rotating Plates and Spirals

In some smaller plants slowly revolving plates or spirals are used which are partially submerged in the liquor. A biotic floc is created which provides the required substrate.

High-charged and low-charged purification systems

In the high-charged system, the bacteria are fed large quantities of "food" quickly. In a low-charged system the bacteria have a resting period between 'meals'.

Differences between high- and low-charged systems:

• High-charged
  • Large amount of bacterial mass (a large part is surplus)
  • Lifetime of bacteria is short
  • Bacteria converting nitrogen to nitrate can't do this because the generation time of the bacteria is much longer than the age of the sludge

• Low-charged
  • The bacterial mass will degrade
  • Longer lifetime of the bacteria (up to three weeks)
  • Less surplus
  • Better conversion of nitrogen in nitrate

Secondary sedimentation

The final step in the secondary treatment stage is to settle out the biological floc or filter material and produce an effluent with very low levels of organic material and suspended matter.

Secondary Sedimentation tank at a rural treatment plant

Download high resolution version (1296x972, 636 KB)sewage treatment secondary settlement tank File links The following pages link to this file: Sewage treatment Categories: GFDL images ... Download high resolution version (1296x972, 636 KB)sewage treatment secondary settlement tank File links The following pages link to this file: Sewage treatment Categories: GFDL images ...

Tertiary treatment

Tertiary treatment provides a final stage to raise the effluent quality to the standard required before it is discharged to the receiving environment (sea, river, lake, ground, etc.) More than one tertiary treatment process may be used at any treatment plant. If disinfection is practiced, it is always the final process.

Effluent polishing

Filtration

Slow sand filtration removes much of the residual suspended matter. Filtration over activated carbon removes residual toxins. Activated carbon (also called activated charcoal) is the more general term which includes carbon material mostly derived from charcoal. ... For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ...

Lagooning

Lagoons provides settlement and further biological improvement through storage in large man-made ponds or lagoons. A lagoon is a body of comparatively shallow salt water separated from the deeper sea by a shallow or exposed sandbank, coral reef, or similar feature. ...

Constructed wetlands

These include engineered reed beds and a range of similar methodologies, all of which provide a high degree of aerobic biological improvement and can often be used instead of secondary treatment for small communities, also see phytoremediation. A constructed wetland is an artificial marsh or swamp, created for human use, such as wastewater or sewage treatment, as habitat to attract wildlife, or for land reclamation after mining or other disturbance. ... species Pragmites australis Reed is a generic term used to describe numerous plants including: Common Reed (Phragmites australis Cav. ... Phytoremediation is the technical term used to describe the treatment of environmental problems (remediation) through the use of plants. ...

Nutrient removal

Wastewater may also contain high levels of nutrients (nitrogen and phosphorus) that in certain forms may be toxic to fish and invertebrates at very low concentrations(e.g. ammonia) or that can create nuisance conditions in the receiving environment (e.g. weed or algal growth). Although the growth of weeds and algae may seem to be primarily an aesthetic issue, algae can produce toxins, and in dying their decay and consumption by bacteria in the environment can result in the depletion of oxygen in the water and the possible consequential suffocation of fish. Where receiving rivers discharge to lakes or shallow seas, the added nutrients can cause severe and sometimes irreversible eutrophication with the loss of many sensitive clean water species. The removal of nitrogen and/or phosphorus from wastewater can be achieved either biologically or by chemical precipitation treatment processes. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... This article is about the chemical element. ... For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ... Groups Conodonta Hyperoartia Petromyzontidae (lampreys) Pteraspidomorphi (early jawless fish) Thelodonti Anaspida Cephalaspidomorphi (early jawless fish) Galeaspida Pituriaspida Osteostraci Gnathostomata (jawed vertebrates) Placodermi Chondrichthyes (cartilaginous fish) Acanthodii Osteichthyes (bony fish) Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) A fish is a poikilothermic (cold-blooded)* water-dwelling... Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Aesthetics (also esthetics) is the philosophy of beauty and art. ... Eutrophication is apparent as increased turbidity in the northern part of the Caspian Sea, imaged from orbit. ...

Nitrogen removal

Biological treatment of nitrogen generally involves creating conditions within the treatment process for bacteria to convert the ammonia to nitrate (nitrification), and then allowing other bacteria to reducing the nitrate to nitrogen gas (denitrification), which is released to the atmosphere. Sand filters, lagooning and the use of reed beds can all be used to reduce nitrogen. Sometimes the conversion of toxic ammonia to nitrate alone is referred to as tertiary treatment.

Phosphorus removal

The biological treatment of wastewater to remove phosphorus also involves the design and creation of specific environmental conditions within a treatment plant to enable specific bacteria to bio-accumulate large quantities of phosphorus. When the bacteria containing the phosphorus are removed, the resulting bacterial biosolids often have a high fertilizer value. Phosphorus can also be removed by chemical precipitation using (commonly) salts of iron (e.g. ferric chloride) or aluminum (e.g. alum). The resulting chemical sludge, however, is difficult to dispose of, and the use of chemicals in the treatment process is expensive and makes operation difficult and often messy. Fertilizers or fertilisers are compounds given to plants with the intention of promoting growth; they are usually applied either via the soil, for uptake by plant roots, or by foliar spraying, for uptake through leaves. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... For alum meaning graduate, see Alumn. ...

Disinfection

The purpose of disinfection in the treatment of wastewater is to substantially reduce the number of living organisms in the water to be discharged back into the environment. The effectiveness of disinfection depends on the quality of the water being treated (e.g., turbitidy, pH, etc.), the type of disinfection being used, the disinfectant dosage (concentration and time), and other environmental variables. Turbid water will be treated less successfully since solid matter can shield organisms, especially from Ultraviolet light or if contact times are low. Generally, short contact times, low doses and high flows all militate against effective disinfection. Common methods of disinfection include ozone, chlorine, or UV light. Chloramine, which is used for drinking water, is not used in waste water treatment because of its persistence. Disinfection is the destruction of pathogenic and other kinds of microorganisms by physical or chemical means. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Chloramine (monochloramine) is a toxic substance (NH2Cl) created by the chemical reaction of ammonia and sodium hypochlorite (chlorine bleach) under alkaline conditions. ...

Chlorination remains the most common form of wastewater disinfection in North America due to its low cost and long-term history of effectiveness. One disadvantage is that chlorination of residual organic material can generate chlorinated-organic compounds that may be carcinogenic or harmful to the environment. Residual chlorine or chloramines may also be capable of chlorinating organic material in the natural aquatic environment. Further, because residual chlorine is toxic to aquatic species, the treated effluent must also be chemically dechlorinated, adding to the complexity and cost of treatment.

Ultraviolet (UV) Light is becoming the most common means of disinfection in the UK because of the concerns about the impacts of chlorine in chlorinating residual organics in the wastewater and in chlorinating organics in the receiving water. UV radiation is used to damage the genetic structure of bacteria, viruses, and other pathogens, making them incapable of reproduction. The key disadvantages of UV disinfection are the need for frequent lamp maintenance and replacement and the need for a highly treated effluent to ensure that the target microorganisms are not shielded from the UV radiation (i.e., any solids present in the treated effluent may protect microorganisms from the UV light).

Ozone O₃ is generated by passing oxygen O₂ through a high voltage potential resulting in a third oxygen atom becoming attached and forming O₃. Ozone is very unstable and reactive and oxidizes most organic material it comes in contact with, thereby destroying many disease-causing microorganisms. Ozone is considered to be safer than chlorine because, unlike chlorine which has to be stored on site (highly poisonous in the event of an accidental release), ozone is generated onsite as needed. Ozonation also produces fewer disinfection by-products than chlorination. A disadvantage of ozone disinfection is the high cost of the ozone generation equipment and the requirements for highly skilled operators.

General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Atomic mass 35. ... World map showing location of North America A satellite composite image of North America North America is a continent in the northern hemisphere, bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west... In pathology, a carcinogen is any substance or agent that promotes cancer. ... A virus is a small particle that infects cells in biological organisms. ... Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... This article may be too technical for most readers to understand. ... Properties For alternative meanings see atom (disambiguation). ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ...

Package plants and batch reactors

In order to use less space, treat difficult waste, deal with intermittent flow or achieve higher environmental standards, a number of designs of hybrid treatment plants have been produced. Such plants often combine all or at least two stages of the three main treatment stages into one combined stage. In the UK, where a large number of sewage treatment plants serve small populations, package plants are a viable alternative to building discrete structures for each process stage. One process which combines secondary treatment and settlement is the Sequential Batch Reactor (SBR). Typically, activated sludge is mixed with raw incoming sewage and mixed and aerated. The resultant mixture is then allowed to settle producing a high quality effluent. The settled sludge is run off and re-aerated before a proportion is returned to the head of the works. The disadvantage of such processes is that a high level of control of timing, mixing and aertaion is required which can only be achieved by computer control linked to a range of sensors in the plant. These plants are technologically sophisticated and are unsuited to environments where such control may be unreliable or where the power supply may be intermittent. SBR plants are now being deployed in many parts of the world including North Liberty, Iowa, and Llanasa, North Wales. In biology, hybrid has three meanings. ... North Liberty is a city located in Johnson County, Iowa. ... North Wales is the northernmost region of Wales, bordered to the south by Mid Wales. ...

Sludge treatment

The coarse primary solids and secondary biosolids (bacteria) accumulated in a wastewater treatment process must be treated and disposed of in a safe and effective manner. This material is often inadvertently contaminated with toxic organic and inorganic compounds (e.g. heavy metals). The purpose of digestion is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids. The most common treatment options include anaerobic digestion, aerobic digestion, and composting. The Water Environment Federation (WEF) formally recognized the term biosolids in 1991 and it is in common use thoughout the world as of 2004. ... For other meanings, see heavy metal The term heavy metal may have various more general or more specific meanings. ... Organic has several meanings and related topics. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Anaerobic is a technical word which literally means without air. ... Compost is the decomposed remnants of organic materials (those with plant and animal origins). ...

Anaerobic digestion

Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen. The process can either be thermophilic digestion (in which sludge is fermented in tanks heated to about 38°C) or mesophilic digestion (cold digestion of sludge where sludge is maintained in large tanks for weeks to allow natural mineralisation of the sludge). Thermophilic digestion generates biogas with a high proportion of methane that may be used to both heat the tank and run engines or microturbines for other on-site processes. In large treatment plants sufficient energy can be generated in this way to produce more electricity than the machines require. The methane generation is a key advantage of the anaerobic process. Its key disadvantage is the long time required for the process (up to 30 days) and the high capital cost. Anaerobic is a technical word which literally means without air. ... Thermophiles produce some of the bright colors of Grand Prismatic Spring, Yellowstone National Park A thermophile is an organism – a type of extremophile – which thrives at relatively high temperatures, up to about 60 °C. Many thermophiles are archaea. ... In its strictest sense, fermentation (formerly called zymnosis) is the energy-yielding anaerobic metabolic breakdown of a nutrient molecule, such as glucose, without net oxidation. ... A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, typically between 20 and 45 °C with an optimal temperature near 37 °C, which is the normal temperature of the human body. ... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... Biogas typically refers to methane produced by the fermentation of organic matter including manure, wastewater sludge, or municipal solid waste, under anaerobic conditions. ... The simplest hydrocarbon, methane, is a gas with a chemical formula of CH4. ... An engine is something that produces some effect from a given input. ... This machine has a single-stage radial compressor and turbine, a recuperator, and foil bearings. ... Lightning strikes during a night-time thunderstorm. ...

Aerobic digestion

Aerobic digestion is a bacterial process that runs in the presence of oxygen. Under aerobic conditions, bacteria rapidly consume organic matter and convert it into carbon dioxide. Because the aerobic digestion occurs much faster than anaerobic digestion, the capital costs of aerobic digestion are lower. However, the operating costs are characteristically much greater for aerobic digestion because of the need to add oxygen to the process. Aerobic is an adjective that means requiring air (where air usually means oxygen). ... Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. ...

Composting

Composting is also an aerobic process that involves mixing the wastewater solids with sources of carbon such as sawdust or wood chips. In the presence of oxygen, bacteria digest both the wastewater solids and the added carbon source and, in doing so, produce a large amount of heat. Properly designed and controlled, the heat generated can be sufficient to significantly destroy a sufficient number of the disease-causing microorganisms to enable the resulting composted product to be safely used as a soil amendment material (with similar benefits to peat) for agricultural use. General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... Peat in Lewis, Scotland Peat is an accumulation of partially decayed vegetable matter. ...

Both anaerobic and aerobic digestion processes can result in the destruction of disease-causing microorganisms and parasites to a sufficient level to allow the resulting digested solids to be safely applied to land or used for agriculture as a fertilizer provided that levels of toxic constituents are sufficiently low. A parasite is an organism that lives in or on the living tissue of a host organism at the expense of that host. ...

The choice of a wastewater solid treatment method depends on the amount of solids generated and other site-specific conditions. However, in general, composting is most often applied to smaller-scale applications followed by aerobic digestion and then lastly anaerobic digestion for the larger-scale municipal applications.

Thermal depolymerization

Thermal depolymerization uses hydrous pyrolysis to convert reduced complex organics to oil. Basically, the premacerated, grit-reduced sludge is heated to 250C and compressed to 40 MPa. The hydrogen in the water inserts itself between chemical bonds in natural polymers such as fats, proteins and cellulose. The oxygen of the water combines with carbon, hydrogen and metals. Thermal depolymerization (TDP) is a process for the reduction of complex organic materials (usually waste products of various sorts, often known as biomass) into light crude oil. ... Thermal depolymerization (TDP) is a process for the reduction of complex organic materials (usually waste products of various sorts, often known as biomass) into light crude oil. ... Hydrous pyrolysis refers to the chemical processes which take place when material is heated to high temperatures in the presence of water. ...

The result is oil, light combustible gases such as methane, propane and butane, water with soluble salts, carbon dioxide, and a small residue of inert insoluble material that resembles powdered rock and char.

All organisms and many organic toxins are destroyed. Inorganic salts such as nitrates and phosphates remain in the water after treatment at sufficiently high levels that further treatment is required.

The energy from decompressing the material is recovered, and the process heat and pressure is usually powered from the light combustible gases. The oil is usually treated further to make a defined useful light grade of oil, such as no. 2 diesel and no. 4 heating oil, and then sold.

The process can be made quite efficient.

Sludge disposal

When a liquid sludge is produced, further treatment may be required to make it suitable for final disposal. Typically, sludges are thickened (dewatered) to reduce the volumes transported off-site for disposal. Processes for reducing water content include lagooning in drying beds to produce a cake that can be applied to land or incinerated; pressing, where sludge is mechanically filtered, often through cloth screens to produce a firm cake; and centrifugation where the sludge is thickened by centrifugally separating the solid and liquid. Sludges can be disposed of by liquid injection to land or by disposal in a landfill. There are concerns about sludge incineration because of air pollutants in the emissions, along with the high cost of supplemental fuel, making this a less attractive and less commonly constructed means of sludge treatment and disposal. There is no process which completely eliminates the requirements for disposal of biosolids. A lagoon is a body of comparatively shallow salt water separated from the deeper sea by a shallow or exposed sandbank, coral reef, or similar feature. ... This article needs cleanup. ...

Treatment in the receiving environment

The outlet of a wastewater treating plant flows into a small river

Many processes in a wastewater treatment plant are designed to mimic the natural treatment processes that occur in the environment, whether that environment is a natural water body or the ground. If not overloaded, bacteria in the environment will consume organic contaminants, although this will reduce the levels of oxygen in the water and may significantly change the overall ecology of the receiving water. Native bacterial populations feed on the organic contaminants, and the numbers of disease-causing microorganisms are reduced by natural environmental conditions such as predation, exposure to ultraviolet radiation, etc. Consequently in cases where the receiving environment provides a high level of dilution, a high degree of wastewater treatment may not be required. However, recent evidence has demonstrated that very low levels of certain contaminants in wastewater, including hormones (from animal husbandry and residue from human birth control pills) and synthetic materials such as phthalates that mimic hormones in their action, can have an unpredictable adverse impact on the natural biota and potentially on humans if the water is re-used for drinking water. In the US, uncontrolled discharges of wastewater to the environment are not permitted under law, and strict water quality requirements are to be met. Image File history File links Download high resolution version (1296x972, 128 KB) Please see the file description page for further information. ... Image File history File links Download high resolution version (1296x972, 128 KB) Please see the file description page for further information. ... (Ecology is sometimes used incorrectly as a synonym for the natural environment. ... Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... In general stewardship is responsibility for taking good care of resources entrusted to one. ... Oral contraceptives are contraceptives which are taken orally and inhibit the bodys fertility by chemical means. ... R,R=CnH2n+1; n=4-15 Phthalates are a group of chemical compounds that are mainly used as plasticizers -- substances added to plastics to increase their flexibility. ...

See also

• Agricultural wastewater treatment
• Anaerobic digester
• Industrial wastewater treatment
• John Todd
• Radioactive wastewater treatment
• Select Society of Sanitary Sludge Shovelers
• Water purification
• William Lindley - pioneering 19th century engineer

Agricultural wastewater treatment relates to the treatment of wastewaters produced in the course of agricultural activities. ... Anaerobic digesters are used to create anaerobic, meaning without oxygen, conditions so that anaerobic bacteria can efficiently digest biomass, sewage or other organic matter. ... Industrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by mans industrial or commercial activities prior to its release into the environment or its re-use. ... Dr. John Todd (1939- ) is an important biologist working in the field of ecological design. ... The Select Society of Sanitary Sludge Shovelers (5S) is used by water environment associations (i. ... Water purification, or drinking water treatment, is the process of removing contaminants from surface water or groundwater to make it safe and palatable for human consumption. ... William Lindley (September 7, 1808 - May 22, 1900), was a famous British engineer who together with his sons designed water and sewerage systems for over 30 cities across Europe. ...

External links

• What happens to all the stuff that goes down the toilet? (from The Straight Dope)
• Satellite image of a sewage treatment plant in Vancouver from Google Maps.
• Photos of various waste water treatment plants.
• wastewater treatment worldwide.

Cecil Adams is the pen name of the author of The Straight Dope since 1973, a popular question and answer column published in The Chicago Reader, syndicated in thirty newspapers in the United States and Canada, and available online. ... Members of Parliament Libby Davies, Ujjal Dosanjh, David Emerson, Hedy Fry, Stephen Owen Members of the Legislative Assembly Gordon Campbell, David Chudnovsky, Adrian Dix, Colin Hansen, Jenny Kwan, Lorne Mayencourt, Wally Oppal, Gregor Robertson, Shane Simpson, Carole Taylor Mayor Larry Campbell City Manager Judy Rogers Governing Body Vancouver City Council...