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70-617: Deephams Sewage Treatment Works is a sewage treatment facility close to Picketts Lock , Edmonton , England. The outflow discharges via Pymmes Brook into the River Lee Navigation at Tottenham Lock . The treatment works was upgraded in 2012/13. The treatment works is located at grid reference TQ 359 936 . It is bordered by the A1055 road and the Lea Valley Line railway to the west, Lee Valley golf course to

140-425: A landfill site. Grit is also removed and washed. Some is recycled as a building material, and some goes to landfill. In storm conditions, when the incoming flow exceeds the capacity of the works, some of the sewage is passed through separate storm screens, which perform a similar process, and is stored in storm tanks until the flows reduce, and the contents of the tanks can be processed by the works. The cleared flow

210-559: A concentration), 40–60 g/person/d for BOD (250–400 mg/L), 80–120 g/person/d for COD (450–800 mg/L), 6–10 g/person/d for total nitrogen (35–60 mg/L), 3.5–6 g/person/d for ammonia-N (20–35 mg/L) and 0.7–2.5 g/person/d for total phosphorus (4–15 mg/L). Sewerage (or sewage system) is the infrastructure that conveys sewage or surface runoff ( stormwater , meltwater , rainwater ) using sewers. It encompasses components such as receiving drains , manholes , pumping stations , storm overflows, and screening chambers of

280-525: A low cost treatment option with practically no energy requirements but they require a lot of land. Due to their technical simplicity, most of the savings (compared with high tech systems) are in terms of operation and maintenance costs. Examples for systems that can provide full or partial treatment for toilet wastewater only: Examples for more high-tech, intensive or mechanized, often relatively expensive sewage treatment systems are listed below. Some of them are energy intensive as well. Many of them provide

350-413: A manually cleaned screen may be used. The raking action of a mechanical bar screen is typically paced according to the accumulation on the bar screens and/or flow rate. The solids are collected and later disposed in a landfill, or incinerated. Bar screens or mesh screens of varying sizes may be used to optimize solids removal. If gross solids are not removed, they become entrained in pipes and moving parts of

420-694: A network of pipes and pump stations (called sewerage ) which convey the sewage to a treatment plant. For cities that have a combined sewer , the sewers will also carry urban runoff (stormwater) to the sewage treatment plant. Sewage treatment often involves two main stages, called primary and secondary treatment , while advanced treatment also incorporates a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter (measured as biological oxygen demand ) from sewage,  using aerobic or anaerobic biological processes. A so-called quarternary treatment step (sometimes referred to as advanced treatment) can also be added for

490-814: A network of pipes and pump stations to a municipal treatment plant. This is called a centralized system (see also sewerage and pipes and infrastructure ). A large number of sewage treatment technologies have been developed, mostly using biological treatment processes (see list of wastewater treatment technologies ). Very broadly, they can be grouped into high tech (high cost) versus low tech (low cost) options, although some technologies might fall into either category. Other grouping classifications are intensive or mechanized systems (more compact, and frequently employing high tech options) versus extensive or natural or nature-based systems (usually using natural treatment processes and occupying larger areas) systems. This classification may be sometimes oversimplified, because

560-416: A separate location. 22 sites within a 2-mile (3 km) radius of Deephams were initially identified, and these were then reduced to a short-list of five. An assessment of the whole life cost of using a separate site was then undertaken, and concluded that developing the existing site would be the best way forwards. Any solution required that the works could continue to treat 209,000 tonnes of sewage per day to

630-489: A sewage pumping station, and the complex was served by a network of tramways. A major expansion of the site commenced in 1939, but the onset of the Second World War resulted in the work being suspended until 1948. When work resumed, contracts were awarded to W. & C. French , Holland, Hannen & Cubitts and Marples Ridgway . In the early 1950s, the first of three parallel diffused aeration process streams

700-754: A sludge which can be settled and separated. After separation, a liquid remains that is almost free of solids, and with a greatly reduced concentration of pollutants. Secondary treatment can reduce organic matter (measured as biological oxygen demand) from sewage,  using aerobic or anaerobic processes. The organisms involved in these processes are sensitive to the presence of toxic materials, although these are not expected to be present at high concentrations in typical municipal sewage. Advanced sewage treatment generally involves three main stages, called primary, secondary and tertiary treatment but may also include intermediate stages and final polishing processes. The purpose of tertiary treatment (also called advanced treatment )

770-431: A suitable sewage treatment process, decision makers need to take into account technical and economical criteria. Therefore, each analysis is site-specific. A life cycle assessment (LCA) can be used, and criteria or weightings are attributed to the various aspects. This makes the final decision subjective to some extent. A range of publications exist to help with technology selection. In industrialized countries ,

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840-426: A treatment plant may involve a combination of processes, and the interpretation of the concepts of high tech and low tech, intensive and extensive, mechanized and natural processes may vary from place to place. Examples for more low-tech, often less expensive sewage treatment systems are shown below. They often use little or no energy. Some of these systems do not provide a high level of treatment, or only treat part of

910-544: A very high level of treatment. For example, broadly speaking, the activated sludge process achieves a high effluent quality but is relatively expensive and energy intensive. There are other process options which may be classified as disposal options, although they can also be understood as basic treatment options. These include: Application of sludge , irrigation , soak pit , leach field , fish pond , floating plant pond, water disposal/ groundwater recharge , surface disposal and storage. The application of sewage to land

980-467: Is a parameter used in the design of sewage treatment plants. This concept is known as population equivalent (PE). The base value used for PE can vary from one country to another. Commonly used definitions used worldwide are: 1 PE equates to 60 gram of BOD per person per day, and it also equals 200 liters of sewage per day. This concept is also used as a comparison parameter to express the strength of industrial wastewater compared to sewage. When choosing

1050-509: Is achieved by removing contaminants from the sewage. It is a form of waste management . With regards to biological treatment of sewage, the treatment objectives can include various degrees of the following: to transform or remove organic matter, nutrients (nitrogen and phosphorus), pathogenic organisms, and specific trace organic constituents (micropollutants). Some types of sewage treatment produce sewage sludge which can be treated before safe disposal or reuse. Under certain circumstances,

1120-605: Is also joined by the Chingford Branch Sewer, which serves the western part of the London Borough of Waltham Forest . By 2011, the site was the fourth largest of the sewage treatment works operated by Thames Water , and served a population equivalent of 885,000. Much of the equipment was in need of renewal, and levels of suspended solids , biochemical oxygen demand and total ammonia allowed in treated effluent were to be lowered from 31 March 2017, under

1190-679: Is because the main important factors to be considered when evaluating and selecting sewage treatment processes are numerous. They include: process applicability, applicable flow, acceptable flow variation, influent characteristics, inhibiting or refractory compounds, climatic aspects, process kinetics and reactor hydraulics , performance, treatment residuals, sludge processing, environmental constraints, requirements for chemical products, energy and other resources; requirements for personnel, operating and maintenance; ancillary processes, reliability, complexity, compatibility, area availability. With regards to environmental impacts of sewage treatment plants

1260-405: Is both: a type of treatment and a type of final disposal. It leads to groundwater recharge and/or to evapotranspiration. Land application include slow-rate systems, rapid infiltration, subsurface infiltration, overland flow. It is done by flooding, furrows, sprinkler and dripping. It is a treatment/disposal system that requires a large amount of land per person. The per person organic matter load

1330-523: Is followed by disinfection to ensure that any free floating pathogens, or pathogens associated with the small remaining amount of suspended solids, are rendered ineffective. The use of a very simple cloth filter , consisting of a folded cotton sari , drastically reduces the load of cholera carried in the water, and is suitable for use by the very poor; in this case, an appropriate technology method of disinfection might be added, such as solar water disinfection . A major exception to this generalization

1400-491: Is often encouraged. Disinfection of treated sewage aims to kill pathogens (disease-causing microorganisms) prior to disposal. It is increasingly effective after more elements of the foregoing treatment sequence have been completed. The purpose of disinfection in the treatment of sewage is to substantially reduce the number of pathogens in the water to be discharged back into the environment or to be reused. The target level of reduction of biological contaminants like pathogens

1470-697: Is often regulated by the presiding governmental authority. The effectiveness of disinfection depends on the quality of the water being treated (e.g. turbidity , pH, etc.), the type of disinfection being used, the disinfectant dosage (concentration and time), and other environmental variables. Water with high turbidity 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 , ultraviolet light , or sodium hypochlorite . Monochloramine , which

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1540-444: Is part of the field of sanitation . Sanitation also includes the management of human waste and solid waste as well as stormwater (drainage) management. The term sewage treatment plant is often used interchangeably with the term wastewater treatment plant . The term sewage treatment plant (STP) (or sewage treatment works ) is nowadays often replaced with the term wastewater treatment plant (WWTP). Strictly speaking,

1610-420: Is passed to the primary settlement tanks, where solid material settles out onto the floor of the tank. Mechanical scrapers push this sludge into hoppers, for transfer to the sludge treatment plant. Fat and grease forms a scum on the surface of the tanks, and this is skimmed off. After a period, which allows most of the organic material to settle out, the liquor passes over weirs at the end of the settlement tanks to

1680-414: Is sometimes defined as anything more than primary and secondary treatment in order to allow discharge into a highly sensitive or fragile ecosystem such as estuaries , low-flow rivers or coral reefs . Treated water is sometimes disinfected chemically or physically (for example, by lagoons and microfiltration ) prior to discharge into a stream , river , bay , lagoon or wetland , or it can be used for

1750-457: Is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater . There are a high number of sewage treatment processes to choose from. These can range from decentralized systems (including on-site treatment systems) to large centralized systems involving

1820-570: Is to provide a final treatment stage to further improve the effluent quality before it is discharged to the receiving water body or reused. More than one tertiary treatment process may be used at any treatment plant. If disinfection is practiced, it is always the final process. It is also called effluent polishing . Tertiary treatment may include biological nutrient removal (alternatively, this can be classified as secondary treatment), disinfection and removal of micropollutants, such as environmental persistent pharmaceutical pollutants . Tertiary treatment

1890-417: Is used for drinking water, is not used in the treatment of sewage because of its persistence. Suspended solids It is sometimes abbreviated SS , but is not to be confused with settleable solids , also abbreviated SS, which contribute to the blocking of sewer pipes. Suspended solids are important as pollutants and pathogens are carried on the surface of particles. The smaller the particle size,

1960-536: The Lee Navigation at Tottenham Lock . The works serves a large area of north east London, both inside and outside the M25 corridor. While modern developments tend to segregate rainwater from domestic sewage, and discharge it to local watercourses, many of the sewers within the catchment of the works date from before 1936, and mix the two sources of water together, increasing the volumes that need to be handled by

2030-511: The combined sewer or sanitary sewer . Sewerage ends at the entry to a sewage treatment plant or at the point of discharge into the environment . It is the system of pipes, chambers, manholes or inspection chamber, etc. that conveys the sewage or storm water. Sewage can be treated close to where the sewage is created, which may be called a decentralized system or even an on-site system ( on-site sewage facility , septic tanks , etc.). Alternatively, sewage can be collected and transported by

2100-665: The irrigation of a golf course, greenway or park. If it is sufficiently clean, it can also be used for groundwater recharge or agricultural purposes. Sand filtration removes much of the residual suspended matter. Filtration over activated carbon , also called carbon adsorption, removes residual toxins . Micro filtration or synthetic membranes are used in membrane bioreactors and can also remove pathogens. Settlement and further biological improvement of treated sewage may be achieved through storage in large human-made ponds or lagoons. These lagoons are highly aerobic, and colonization by native macrophytes , especially reeds,

2170-492: The activated sludge process has a high energy consumption because it includes an aeration step. Some sewage treatment plants produce biogas from their sewage sludge treatment process by using a process called anaerobic digestion . This process can produce enough energy to meet most of the energy needs of the sewage treatment plant itself. For activated sludge treatment plants in the United States, around 30 percent of

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2240-422: The annual operating costs is usually required for energy. Most of this electricity is used for aeration, pumping systems and equipment for the dewatering and drying of sewage sludge . Advanced sewage treatment plants, e.g. for nutrient removal, require more energy than plants that only achieve primary or secondary treatment. Small rural plants using trickling filters may operate with no net energy requirements,

2310-399: The average flows. Such basins can improve the performance of the biological treatment processes and the secondary clarifiers. Disadvantages include the basins' capital cost and space requirements. Basins can also provide a place to temporarily hold, dilute and distribute batch discharges of toxic or high-strength wastewater which might otherwise inhibit biological secondary treatment (such

2380-472: The bottom while oil, grease and lighter solids float to the surface and are skimmed off. These basins are called primary sedimentation tanks or primary clarifiers and typically have a hydraulic retention time (HRT) of 1.5 to 2.5 hours. The settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment. Primary settling tanks are usually equipped with mechanically driven scrapers that continually drive

2450-414: The chief chemist, and William Lockett, the chief research assistant, in 1914. The activated sludge and partially treated sewage pass on to the final settlement tanks, where the sludge settles out. Some of the sludge is fed back into the aeration lanes, to assist the start of the secondary treatment process, while some is surplus, so is dewatered and passes on to the sludge treatment process. The liquid from

2520-416: The collected sludge towards a hopper in the base of the tank where it is pumped to sludge treatment facilities. Sewage treatment plants that are connected to a combined sewer system sometimes have a bypass arrangement after the primary treatment unit. This means that during very heavy rainfall events, the secondary and tertiary treatment systems can be bypassed to protect them from hydraulic overloading, and

2590-400: The existing standards while the work was progressing. The works railway was of 2 ft ( 610 mm ) gauge, and was constructed in the 1920s. Four diesel and two petrol locomotives were used during the life of the railway system, which closed around 1968, when the remaining three locomotives were sold on for further work elsewhere. Details of the locomotives are summarised below. Two of

2660-597: The factories themselves to reduce the pollutant load , before discharge to the sewer. The pretreatment has the following two main aims: Firstly, to prevent toxic or inhibitory compounds entering the biological stage of the sewage treatment plant and reduce its efficiency. And secondly to avoid toxic compounds from accumulating in the produced sewage sludge which would reduce its beneficial reuse options. Some industrial wastewater may contain pollutants which cannot be removed by sewage treatment plants. Also, variable flow of industrial waste associated with production cycles may upset

2730-400: The farm had become Edmonton sewage farm. The works included three rectangular filter beds and a large building. By 1914, both facilities were owned by Edmonton Urban District , and the farm had expanded to include a large irregular-shaped filter bed. Major expansion had taken place by the 1930s, with humus tanks to the west, sludge beds to the north and filter beds to the east. In the middle was

2800-437: The fat floating on the surface. Air blowers in the base of the tank may also be used to help recover the fat as a froth. Many plants, however, use primary clarifiers with mechanical surface skimmers for fat and grease removal. Primary treatment is the "removal of a portion of the suspended solids and organic matter from the sewage". It consists of allowing sewage to pass slowly through a basin where heavy solids can settle to

2870-530: The final settlement tanks is of sufficient quality that it can be discharged into Salmons Brook , from where it makes its way into the Lee Navigation via Pymmes Brook. Before discharge, some of the water is passed through a tertiary treatment phase, where a fine filter is used to remove residual fine particles. The woven mesh membrane must be washed periodically to remove any accumulated sediments. Disk filters capable of treating between 40 and 50 per cent of

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2940-423: The finer grit passes through the grit removal flows under normal conditions. During periods of high flow deposited grit is resuspended and the quantity of grit reaching the treatment plant increases substantially. Equalization basins can be used to achieve flow equalization. This is especially useful for combined sewer systems which produce peak dry-weather flows or peak wet-weather flows that are much higher than

3010-605: The following aspects are included in the selection process: Odors, vector attraction, sludge transportation, sanitary risks, air contamination , soil and subsoil contamination, surface water pollution or groundwater contamination , devaluation of nearby areas, inconvenience to the nearby population. Odors emitted by sewage treatment are typically an indication of an anaerobic or septic condition. Early stages of processing will tend to produce foul-smelling gases, with hydrogen sulfide being most common in generating complaints. Large process plants in urban areas will often treat

3080-748: The frequency of tank cleaning caused by excessive accumulation of grit; and (3) protect moving mechanical equipment from abrasion and accompanying abnormal wear. The removal of grit is essential for equipment with closely machined metal surfaces such as comminutors, fine screens, centrifuges, heat exchangers, and high pressure diaphragm pumps. Grit chambers come in three types: horizontal grit chambers, aerated grit chambers, and vortex grit chambers. Vortex grit chambers include mechanically induced vortex, hydraulically induced vortex, and multi-tray vortex separators. Given that traditionally, grit removal systems have been designed to remove clean inorganic particles that are greater than 0.210 millimetres (0.0083 in), most of

3150-418: The greater the total surface area per unit mass of particle in grams, and so the higher the pollutant load that is likely to be carried. Removal of suspended solids is generally achieved through the use of sedimentation and/or water filters (usually at a municipal level). By eliminating most of the suspended solids in a water supply, the significant water is usually rendered close to drinking quality. This

3220-420: The homes in the U.S. Sewage treatment often involves two main stages, called primary and secondary treatment, while advanced treatment also incorporates a tertiary treatment stage with polishing processes. Different types of sewage treatment may utilize some or all of the process steps listed below. Preliminary treatment (sometimes called pretreatment) removes coarse materials that can be easily collected from

3290-415: The latter is a broader term that can also refer to industrial wastewater treatment. The terms water recycling center or water reclamation plants are also in use as synonyms. The overall aim of treating sewage is to produce an effluent that can be discharged to the environment while causing as little water pollution as possible, or to produce an effluent that can be reused in a useful manner. This

3360-469: The locomotives still exist, and have been privately preserved. Motor Rail No 2 is at Eynsford, Kent, and Motor Rail No 3 is near Buxton in Derbyshire. Sewage arrives at the works through the three trunk sewers, which are deep underground. The effluent is therefore pumped up to the inlet works, where debris such as cloth, paper and plastic is removed. It is washed and dumped into skips, to be taken to

3430-483: The main criteria for selection are: desired effluent quality, expected construction and operating costs, availability of land, energy requirements and sustainability aspects. In developing countries and in rural areas with low population densities, sewage is often treated by various on-site sanitation systems and not conveyed in sewers. These systems include septic tanks connected to drain fields , on-site sewage systems (OSS), vermifilter systems and many more. On

3500-421: The mixture of sewage and storm-water receives primary treatment only. Primary sedimentation tanks remove about 50–70% of the suspended solids, and 25–40% of the biological oxygen demand (BOD). The main processes involved in secondary sewage treatment are designed to remove as much of the solid material as possible. They use biological processes to digest and remove the remaining soluble material, especially

3570-400: The most important parameters in process selection are typically efficiency, reliability, and space requirements. In developing countries , they might be different and the focus might be more on construction and operating costs as well as process simplicity. Choosing the most suitable treatment process is complicated and requires expert inputs, often in the form of feasibility studies . This

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3640-490: The north, the William Girling Reservoir and the Lee Navigation to the east, and an industrial park to the south. Treatment of sewage in the area began in the late nineteenth century. The 1881 Ordnance Survey map shows open fields and Deephams farm between the railway and the navigation, but by 1896, housing has begun to appear. Edmonton Sewage Works was built on a site to the west of the railway, and

3710-520: The odors with carbon reactors, a contact media with bio-slimes, small doses of chlorine , or circulating fluids to biologically capture and metabolize the noxious gases. Other methods of odor control exist, including addition of iron salts, hydrogen peroxide , calcium nitrate , etc. to manage hydrogen sulfide levels. The energy requirements vary with type of treatment process as well as sewage strength. For example, constructed wetlands and stabilization ponds have low energy requirements. In comparison,

3780-400: The organic fraction. This can be done with either suspended-growth or biofilm processes. The microorganisms that feed on the organic matter present in the sewage grow and multiply, constituting the biological solids, or biomass. These grow and group together in the form of flocs or biofilms and, in some specific processes, as granules. The biological floc or biofilm and remaining fine solids form

3850-512: The other hand, advanced and relatively expensive sewage treatment plants may include tertiary treatment with disinfection and possibly even a fourth treatment stage to remove micropollutants. At the global level, an estimated 52% of sewage is treated. However, sewage treatment rates are highly unequal for different countries around the world. For example, while high-income countries treat approximately 74% of their sewage, developing countries treat an average of just 4.2%. The treatment of sewage

3920-436: The population dynamics of biological treatment units. Urban residents in many parts of the world rely on on-site sanitation systems without sewers, such as septic tanks and pit latrines , and fecal sludge management in these cities is an enormous challenge. For sewage treatment the use of septic tanks and other on-site sewage facilities (OSSF) is widespread in some rural areas, for example serving up to 20 percent of

3990-429: The raw sewage before they damage or clog the pumps and sewage lines of primary treatment clarifiers . The influent in sewage water passes through a bar screen to remove all large objects like cans, rags, sticks, plastic packets, etc. carried in the sewage stream. This is most commonly done with an automated mechanically raked bar screen in modern plants serving large populations, while in smaller or less modern plants,

4060-460: The removal of organic micropollutants, such as pharmaceuticals. This has been implemented in full-scale for example in Sweden. A large number of sewage treatment technologies have been developed, mostly using biological treatment processes. Design engineers and decision makers need to take into account technical and economical criteria of each alternative when choosing a suitable technology. Often,

4130-462: The secondary treatment process. This consists of aeration lanes, where air is pumped through the liquor, to encourage the growth of bacteria which are already present in the wastewater. The bacteria digest the remaining organic material which is suspended or dissolved in the water. The bacteria form an activated sludge, a process developed at Davyhulme Sewage Works in Manchester by Edward Ardern,

4200-475: The sewage (for example only the toilet wastewater ), or they only provide pre-treatment, like septic tanks. On the other hand, some systems are capable of providing a good performance, satisfactory for several applications. Many of these systems are based on natural treatment processes, requiring large areas, while others are more compact. In most cases, they are used in rural areas or in small to medium-sized communities. For example, waste stabilization ponds are

4270-494: The structure of the sludge. This process produces biogas , which is used in a combined heat and power plant to supply some of the energy needs of the whole treatment process. The end product is a fertiliser rich in nutrients, which is used in agriculture. Sewage treatment Sewage treatment (or domestic wastewater treatment , municipal wastewater treatment ) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that

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4340-567: The terms of the Freshwater Fish Directive and the Water Framework Directive . A major reconstruction project was begun, which involved increasing the capacity of the works to cater for a population equivalent of 941,000 and a peak inlet flow of 497 Megalitres per day (Mld). Because of the constrained nature of the site, consideration was given, during the design phase, to building part of the new works at

4410-650: The treated sewage sludge might be termed biosolids and can be used as a fertilizer . Typical values for physical–chemical characteristics of raw sewage in developing countries have been published as follows: 180 g/person/d for total solids (or 1100 mg/L when expressed as a concentration), 50 g/person/d for BOD (300 mg/L), 100 g/person/d for COD (600 mg/L), 8 g/person/d for total nitrogen (45 mg/L), 4.5 g/person/d for ammonia-N (25 mg/L) and 1.0 g/person/d for total phosphorus (7 mg/L). The typical ranges for these values are: 120–220 g/person/d for total solids (or 700–1350 mg/L when expressed as

4480-486: The treatment plant, and can cause substantial damage and inefficiency in the process. Grit consists of sand , gravel , rocks, and other heavy materials. Preliminary treatment may include a sand or grit removal channel or chamber, where the velocity of the incoming sewage is reduced to allow the settlement of grit. Grit removal is necessary to (1) reduce formation of deposits in primary sedimentation tanks, aeration tanks, anaerobic digesters, pipes, channels, etc. (2) reduce

4550-450: The whole process being driven by gravitational flow, including tipping bucket flow distribution and the desludging of settlement tanks to drying beds. This is usually only practical in hilly terrain and in areas where the treatment plant is relatively remote from housing because of the difficulty in managing odors. In highly regulated developed countries, industrial wastewater usually receives at least pretreatment if not full treatment at

4620-405: The works flow were installed in 2012, and Thames Water hoped to increase this to allow all of the flow to be filtered by 2015. Sludge and scum from the primary settlement tanks has its water content lowered, and is then stored to allow levels of bacteria and pathogens to reduce naturally. The speed of this process is increased by heating the sludge in digestion tanks, enabling bacteria to break down

4690-625: The works. Local sewers feed into three main gravity trunk sewers, which deliver effluent to the works. Waltham Abbey , Cheshunt , Cuffley and north east Enfield are connected to the Lee Valley Sewer. South and west Enfield, and east Barnet are served by the Barnet High Level Sewer, while the Tottenham Low Level Sewer transports sewage from Tottenham , Wood Green and south east Enfield. It

4760-407: Was completed, which included primary and secondary treatment of the effluent. This was known as Stream A, and was followed by Stream B, completed in 1956, and Stream C, completed in 1966. By that time the site occupied an area of 86 acres (35 ha), and the works to the west of the railway had been demolished. Upgrades to the infrastructure were carried out in the 1980s, when screening of storm flows

4830-427: Was introduced, and in the 1990s, when a sludge digestion facility was built. Improvements to the inlet works were again carried out in 2011/12, when the capacity of the storm storage tanks was also increased. Treated effluent from the site is discharged into Salmons Brook , and the quality of this effluent has gradually improved as the works have been modified. Salmons Brook flows into Pymmes Brook and subsequently into

4900-409: Was wastewater from portable toilets or fecal sludge that is brought to the sewage treatment plant in vacuum trucks ). Flow equalization basins require variable discharge control, typically include provisions for bypass and cleaning, and may also include aerators and odor control. In some larger plants, fat and grease are removed by passing the sewage through a small tank where skimmers collect

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