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143-407: The term "septic" refers to the anaerobic bacterial environment that develops in the tank that decomposes or mineralizes the waste discharged into the tank. Septic tanks can be coupled with other onsite wastewater treatment units such as biofilters or aerobic systems involving artificially forced aeration . The rate of accumulation of sludge—also called septage or fecal sludge —is faster than

286-450: A soil conditioner , anaerobic digestion for the production of biogas , forms of dry-combustion fuel such as pellets or biochar , charcoal , biodiesel , sludge and plants or protein production as animal fodder . Fecal sludge management refers to the storage, collection, transport, treatment, and safe end use or disposal of fecal sludge. Collectively, the collection, transport, treatment and end use or reuse of excreta constitute

429-461: A T pipe, allowing liquid to enter and exit without disturbing any crust on the surface. Today, the design of the tank usually incorporates two chambers, each equipped with an access opening and cover, and separated by a dividing wall with openings located about midway between the floor and roof of the tank. Wastewater enters the first chamber of the tank, allowing solids to settle and scum to float. The settled solids are anaerobically digested, reducing

572-405: A benefit to using thermophilic temperatures instead of mesophilic. Additional pre-treatment can be used to reduce the necessary retention time to produce biogas. For example, certain processes shred the substrates to increase the surface area or use a thermal pretreatment stage (such as pasteurisation) to significantly enhance the biogas output. The pasteurisation process can also be used to reduce

715-484: A biogas with a elevated methane content. The produced carbon dioxide in biogas dissolves more into the water phase under pressure then methane does. Hence the produced biogas is richer in methane. Research at the University of Groningen demonstrated that the bacterial community changes in composition under the influence of pressure. Individual bacteria species have their optimum circumstances in which they grow and replicate

858-411: A broader urban sanitation program during 2014–2017. FSM services can be provided as demand based (often called on-request, on-call, on-demand, ad-hoc or non-scheduled) or scheduled (also known as regular) desludging, or a combination of both. Under either mechanism, OSSFs are desludged on a periodic basis or when the household requests it or due to inspection by a competent authority indicates desludging

1001-410: A chain length greater than that of acetate must first be catabolised into compounds that can be directly used by methanogens. The biological process of acidogenesis results in further breakdown of the remaining components by acidogenic (fermentative) bacteria. Here, VFAs are created, along with ammonia, carbon dioxide, and hydrogen sulfide , as well as other byproducts. The process of acidogenesis

1144-530: A code of practice has been developed by the Environmental Protection Agency to regulate the planning and construction of new septic tanks, secondary treatment systems, septic drain fields and filter systems. Direct discharge of septic tank effluent into groundwater is prohibited in Ireland, while the indirect discharge via unsaturated subsoil into groundwater, e.g. by means of a septic drain field, or

1287-407: A domino effect of inhibition. Total ammonia nitrogen is the combination of free ammonia and ionized ammonia. TAN is produced through degrading material high in nitrogen, typically proteins and will naturally build in anaerobic digestion. This is depending on the organic feed stock fed to the system. In typical wastewater treatment practices, TAN reduction is done with via nitrification . Nitrification

1430-409: A drain field. Septic tank effluent can also be conveyed to a secondary treatment, typically constructed wetlands. Constructed wetlands benefit from the good performance of septic tanks at removing solids, which avoids them getting clogged quickly. Septic tank effluent can also be conveyed to a centralized treatment facility. The remaining impurities are trapped and eliminated in the soil , with

1573-611: A farm-based digester that uses dairy manure as the primary feedstock, the gas production may be significantly increased by adding a second feedstock, e.g., grass and corn (typical on-farm feedstock), or various organic byproducts, such as slaughterhouse waste, fats, oils and grease from restaurants, organic household waste, etc. (typical off-site feedstock). Digesters processing dedicated energy crops can achieve high levels of degradation and biogas production. Slurry-only systems are generally cheaper, but generate far less energy than those using crops, such as maize and grass silage; by using

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1716-523: A frozen lake in Alaska" has produced 200–300 litres of methane per day, about 20 to 30% of the output from digesters in warmer climates. Mesophilic species outnumber thermophiles, and they are also more tolerant to changes in environmental conditions than thermophiles. Mesophilic systems are, therefore, considered to be more stable than thermophilic digestion systems. In contrast, while thermophilic digestion systems are considered less stable, their energy input

1859-439: A gas-tight door. Neither approach has mixing inside the digester. The amount of pretreatment, such as contaminant removal, depends both upon the nature of the waste streams being processed and the desired quality of the digestate. Size reduction (grinding) is beneficial in continuous vertical systems, as it accelerates digestion, while batch systems avoid grinding and instead require structure (e.g. yard waste) to reduce compaction of

2002-420: A global warming potential about 25 times larger than carbon dioxide. This makes septic tanks potential greenhouse gas emitters. The same methane can be burnt to produce energy for local usage. Septic tanks by themselves are ineffective at removing nitrogen compounds that have potential to cause algal blooms in waterways into which affected water from a septic system finds its way. This can be remedied by using

2145-439: A high percentage of solids (40-60%) in gas-tight chambers called fermenter boxes. It is with this understanding that mechanical biological treatment plants are designed. The higher the level of pretreatment a feedstock requires, the more processing machinery will be required, and, hence, the project will have higher capital costs. National Non-Food Crops Centre . After sorting or screening to remove any physical contaminants from

2288-479: A high percentage of water connectivity (homes with piped water connections) are logical operators of FSM programs. If water is sold to customers through a tariff, an additional tariff to cover FSM services may be added. For larger cities, it is usually the water and sewerage service provider that will be the most appropriate operator. Local governments may choose to provide services by using their own staff and resources for collection, transportation and treatment. This

2431-446: A lack of technical expertise and experience; an inability to source funds for to purchase of vacuum trucks and treatment, as well as a lack of knowledge necessary to initiate and implement successful FSM programs. Another factor is that the transporting fecal sludge has a real cost to vacuum truck operators and there is thus an incentive to dispose of the untreated waste into the environment (primarily into waterways, but also directly onto

2574-472: A larger volume of the digesters (spread across several batches) to handle the same amount of waste as a continuous process digester. Higher heat energy is required in a thermophilic system compared to a mesophilic system, but the thermophilic system requires much less time and has a larger gas output capacity and higher methane gas content, so one has to consider that trade-off carefully. For solids content, low will handle up to 15% solid content. Above this level

2717-565: A limited time, but becomes less effective as a primary remediation strategy as population density increases. In areas adjacent to water bodies with fish or shellfish intended for human consumption, improperly maintained and failing septic systems contribute to pollution levels that can force harvest restrictions and/or commercial or recreational harvest closures. In the United States , the 2008 American Housing Survey indicated that about 20 percent of all households rely on septic tanks, and that

2860-428: A liquid environment, as it enables more thorough circulation of materials and contact between the bacteria and their food. This enables the bacteria to more readily access the substances on which they are feeding, and increases the rate of gas production. Digestion systems can be configured with different levels of complexity. In a single-stage digestion system (one-stage), all of the biological reactions occur within

3003-612: A means of providing services. A WSP study recommended that efforts to introduce scheduled emptying should focus first on areas where demand was greatest, moving on to other areas when the success of scheduled emptying had been demonstrated in these areas. Analysis of pit and tank desludging records for Palu in Indonesia revealed that existing demand for desludging services varied between sub-districts, with demand being greatest in well-established areas and least in urban fringe areas. There are multiple benefits of scheduled desludging services in

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3146-463: A mix of onsite-sanitation systems and services, decentralized wastewater management systems, or by condominial or simplified sewerage connected to decentralized or centralized treatment. In all of these situations, FSM is a necessary service to keep the sanitation systems functioning properly. Rural areas with low population density may not need formal FSM services if the local practice is to cover and rebuild latrines when they fill up. However, if this

3289-480: A modest amount of crop material (30%), an anaerobic digestion plant can increase energy output tenfold for only three times the capital cost, relative to a slurry-only system. A second consideration related to the feedstock is moisture content. Drier, stackable substrates, such as food and yard waste, are suitable for digestion in tunnel-like chambers. Tunnel-style systems typically have near-zero wastewater discharge, as well, so this style of system has advantages where

3432-409: A nitrogen-reducing technology, such as hybrid constructed wetlands, or by simply ensuring that the leach field is properly sited to prevent direct entry of effluent into bodies of water. The fermentation processes cause the contents of a septic tank to be anaerobic with a low redox potential, which keeps phosphates in a soluble and, thus, mobilized form. Phosphates discharged from a septic tank into

3575-402: A number of chemical processes in converting the biomass to biogas . Gaseous oxygen is excluded from the reactions by physical containment. Anaerobes utilize electron acceptors from sources other than oxygen gas. These acceptors can be the organic material itself or may be supplied by inorganic oxides from within the input material. When the oxygen source in an anaerobic system is derived from

3718-399: A number of different configurations and can be categorized into batch vs. continuous process mode, mesophilic vs. thermophilic temperature conditions, high vs. low portion of solids, and single stage vs. multistage processes. Continuous process requires more complex design, but still, it may be more economical than batch process, because batch process requires more initial building money and

3861-468: A permit or qualify for an exemption with the Environment Agency . Permits need to be granted to systems that discharge more than a certain volume of effluent in a given time or that discharge effluent directly into sensitive areas (e.g., some groundwater protection zones). In general, permits are not granted for new septic tanks that discharge directly into surface waters. A septic tank discharging into

4004-446: A rapid increase in evidence-based research and journal publications on the topic (e.g. for Africa and Asia ). There are rapidly evolving technology developments along the entire service chain. Some have the potential to alter the existing service chain, such as container-based sanitation, decentralized options, and innovations developed through the Bill & Melinda Gates Foundation 'Reinvent

4147-554: A significant percentage of homes cannot be accessed by tanker truck should utilize transfer stations. Transfer stations are used if: Mobile transfer stations are nothing more than larger tanker trucks or trailers that are deployed along with small vacuum trucks and motorcycle or hand carts. The smaller vehicles discharge to the larger tanker, which then carries the collected sludge to the treatment plant. These work well in scheduled desludging business models. Fixed transfer stations are dedicated facilities installed strategically throughout

4290-496: A single, sealed reactor or holding tank. Using a single stage reduces construction costs, but results in less control of the reactions occurring within the system. Acidogenic bacteria, through the production of acids, reduce the pH of the tank. Methanogenic archaea, as outlined earlier, operate in a strictly defined pH range. Therefore, the biological reactions of the different species in a single-stage reactor can be in direct competition with each other. Another one-stage reaction system

4433-423: A small tank pulled by a motorcycle, or in containers on a handcart. The wider use of multiple decentralized sludge treatment facilities within cities (to avoid long haulage distances) is currently being researched and piloted. Fecal sludge is different to wastewater and cannot simply be co-treated at sewage treatment plants. Small additions of fecal sludge are possible if plants are underutilized and able to take

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4576-583: A watercourse must be replaced or upgraded by 1 January 2020 to a Sewage Treatment Plant (also called an Onsite sewage facility ), or sooner if the property is sold before this date, or if the Environment Agency (EA) finds that it is causing pollution. In Northern Ireland , the Department of the Environment must give permission for all wastewater discharges where it is proposed that the discharge will go to

4719-760: A waterway or soil infiltration system. The discharge consent will outline conditions relating to the quality and quantity of the discharge in order to ensure the receiving waterway or the underground aquifer can absorb the discharge. The Water Environment Regulations 2011 regulate the registration of septic tank systems in Scotland . Proof of registration is required when new properties are being developed or existing properties change ownership. In Australia, septic tank design and installation requirements are regulated by State Governments, through Departments of Health and Environmental Protection Agencies. Regulation may include Codes of Practice and Legislation. Regulatory requirements for

4862-451: Is a major factor in determining the methane yield and methane production rates from the digestion of biomass. Techniques to determine the compositional characteristics of the feedstock are available, while parameters such as solids, elemental, and organic analyses are important for digester design and operation. Methane yield can be estimated from the elemental composition of substrate along with an estimate of its degradability (the fraction of

5005-489: Is a person responsible for cleaning, maintaining, operating, or emptying the equipment or technology at any step of the sanitation chain. This is the definition used in the narrower sense within the WASH sector. More broadly speaking, sanitation workers may also be involved in cleaning streets , parks , public spaces , sewers , storm water drains , and public toilets . Another definition is: "The moment an individual’s waste

5148-685: Is an anaerobic lagoon . These lagoons are pond-like, earthen basins used for the treatment and long-term storage of manures. Here the anaerobic reactions are contained within the natural anaerobic sludge contained in the pool. In a two-stage digestion system (multistage), different digestion vessels are optimised to bring maximum control over the bacterial communities living within the digesters. Acidogenic bacteria produce organic acids and more quickly grow and reproduce than methanogenic archaea. Methanogenic archaea require stable pH and temperature to optimise their performance. Under typical circumstances, hydrolysis, acetogenesis, and acidogenesis occur within

5291-479: Is an aerobic process where TAN is consumed by aerobic heterotrophic bacteria. These bacteria release nitrate and nitrite which are later converted to nitrogen gas through the denitrification process. Hydrolysis and acidogenesis can also be impacted by TAN concentration. In mesophilic conditions, inhibition for hydrolysis was found to occur at 5500 mg/L TAN, while acidogenesis inhibition occurs at 6500 mg/L TAN. The most important initial issue when considering

5434-459: Is applied to its treatment. To use a high-solids anaerobic digester for dilute feedstocks, bulking agents, such as compost, should be applied to increase the solids content of the input material. Another key consideration is the carbon:nitrogen ratio of the input material. This ratio is the balance of food a microbe requires to grow; the optimal C:N ratio is 20–30:1. Excess N can lead to ammonia inhibition of digestion. The level of contamination of

5577-483: Is being used by a large family will require much more frequent pumping than a new system used by only a few people. Anaerobic decomposition is rapidly restarted when the tank is refilled. An empty tank may be damaged by hydrostatic pressure causing the tank to partially "float" out of the ground, especially in flood situations or very wet ground conditions. Another option is "scheduled desludging" of septic tanks which has been initiated in several Asian countries including

5720-427: Is called septage . It is estimated that one-third of the world's population is served by onsite sanitation, and that in low-income countries less than 10% of urban areas are served by sewers. In low-income countries, the majority of fecal sludge is discharged untreated into the urban environment, placing a huge burden on public and environmental health. Hence, FSM plays a critical role in safely managed sanitation and

5863-411: Is collected and either disposed of into the environment or treated offsite. Fecal sludge collection can be arranged on a scheduled basis or on a call-for-service basis (also known as on-demand, on-request, or non-scheduled services). The collected fecal sludge may be manually or mechanically emptied, and then transported to treatment plants with a vacuum truck , a tank and pump mounted on a flatbed truck,

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6006-413: Is considered high solids content and can also be known as dry digestion. In a single stage process, one reactor houses the four anaerobic digestion steps. A multistage process utilizes two or more reactors for digestion to separate the methanogenesis and hydrolysis phases. Anaerobic digestion can be performed as a batch process or a continuous process. In a batch system, biomass is added to the reactor at

6149-403: Is fecal sludge that is accumulated and stored in a septic tank . Septage tends to be more dilute, as septic tanks are typically used with flush toilets ( blackwater ) and can also include grey water . Septic tanks also tend to have less solid waste, as they only receive things that can be flushed down a toilet (e.g. toilet paper ). When operating as designed, a sludge blanket layer accumulates on

6292-441: Is for septic tanks that are prefabricated or factory manufactured and made of polyethylene , glass reinforced polyester , polypropylene , PVC-U , steel or concrete . Part 4 ( EN 12566-4 ) regulates septic tanks that are assembled on site from prefabricated kits, generally of concrete construction. Certified septic tanks of both types must pass a standardized hydraulic test to assess their ability to retain suspended solids within

6435-578: Is higher, with more biogas being removed from the organic matter in an equal amount of time. The increased temperatures facilitate faster reaction rates, and thus faster gas yields. Operation at higher temperatures facilitates greater pathogen reduction of the digestate. In countries where legislation, such as the Animal By-Products Regulations in the European Union, requires digestate to meet certain levels of pathogen reduction there may be

6578-537: Is highly variable, with a very wide range of quantities (i.e. produced and accumulated volumes) and qualities (i.e. characteristics). Fecal sludge is stored onsite, and is periodically collected and transported to a fecal sludge treatment plant, followed by safe disposal or end use. When safely managed, fecal sludge that is collected from pit latrines can also be called "pit latrine sludge", whereas fecal sludge collected from septic tanks can also be called "septic tank sludge" or "septage". Septage or "septic tank sludge"

6721-489: Is needed. An analysis of 20 FSM Innovation Case Studies and research and advocacy of successful programs carried out by Oxfam Philippines has demonstrated that common elements for successful FSM programs include: Sanitation workers are the people responsible for cleaning, maintaining, operating, or emptying a sanitation technology at any step of the sanitation chain. These workers contribute to safe fecal sludge management. A sanitation worker (or sanitary worker)

6864-679: Is not possible, rural areas often lack treatment facilities within a reasonable (say 30 minutes drive) distance; are difficult for tankers to access and often have limited demand for emptying making transport and treatment uneconomic, and unaffordable for most people. Therefore, options such as relocating latrines on-site, double (alternating) pit or Arborloo toilets could be considered. Also sharing decentralized FSM services and sludge treatment between nearby villages, or direct safe removal burial of waste could be considered and organized. Most types of dry toilets (except for pit latrines ) do not generate fecal sludge but generate instead dried feces (in

7007-413: Is not transported through a sewer . It is composed of human excreta , but also anything else that may go into an onsite containment technology, such as flushwater, cleansing materials (e.g. toilet paper and anal cleansing materials), menstrual hygiene products, grey water (i.e. bathing or kitchen water, including fats, oils and grease), and solid waste . Fecal sludge that is removed from septic tanks

7150-466: Is often processed through a series of treatment steps to first separate the liquids from the solids, and then treat both the liquid and solid trains while recovering as much of the energy or nutritive value as possible. Common processes at fecal sludge treatment plants include: Constructed wetlands are gaining attention as a low-cost treatment technology that can be constructed in many instances using local materials and labor. For sites with enough land and

7293-543: Is often the case in smaller cities or municipalities where the water utility may not have a broad reach. In many cases, cooperation between the city government and the water utility may be strategically advantageous. Dumaguete City, Philippines, is one example where the Water District (utility) and Local Government have joint ownership and responsibilities for the FSM program. Organized larger scale FSM programs may be able to provide

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7436-515: Is outsourced to another, it becomes sanitation work." Some organizations use the term specifically for municipal solid waste collectors , whereas others exclude the workers involved in management of solid waste (rubbish, trash) sector from its definition. If the fecal sludge is liquid enough, it is usually collected by using vacuum pumps or centrifugal style booster pumps. A variety of manual and motorized devices designed to excavate thick and viscous sludge and accumulated trash are also available in

7579-399: Is proportional to the volume of wastewater and inversely proportional to the porosity of the drainage field. The entire septic system can operate by gravity alone or, where topographic considerations require, with inclusion of a lift pump . Certain septic tank designs include siphons or other devices to increase the volume and velocity of outflow to the drainage field. These help to fill

7722-573: Is released by methanogenic archaea as methane. Populations of anaerobic microorganisms typically take a significant period of time to establish themselves to be fully effective. Therefore, common practice is to introduce anaerobic microorganisms from materials with existing populations, a process known as "seeding" the digesters, typically accomplished with the addition of sewage sludge or cattle slurry. The four key stages of anaerobic digestion involve hydrolysis , acidogenesis , acetogenesis and methanogenesis . The overall process can be described by

7865-406: Is similar to the way milk sours . The third stage of anaerobic digestion is acetogenesis . Here, simple molecules created through the acidogenesis phase are further digested by acetogens to produce largely acetic acid, as well as carbon dioxide and hydrogen. The terminal stage of anaerobic digestion is the biological process of methanogenesis . Here, methanogens use the intermediate products of

8008-852: Is the source of marsh gas methane as discovered by Alessandro Volta in 1776. Anaerobic digestion comprises four stages: The digestion process begins with bacterial hydrolysis of the input materials. Insoluble organic polymers , such as carbohydrates , are broken down to soluble derivatives that become available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen , ammonia , and organic acids . In acetogenesis, bacteria convert these resulting organic acids into acetic acid , along with additional ammonia, hydrogen, and carbon dioxide amongst other compounds. Finally, methanogens convert these products to methane and carbon dioxide. The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments. Anaerobic digestion

8151-421: Is the storage, collection, transport, treatment and safe end use or disposal of fecal sludge. Together, the collection, transport, treatment and end use of fecal sludge constitute the "value chain" or "service chain" of fecal sludge management. Fecal sludge is defined very broadly as what accumulates in onsite sanitation systems (e.g. pit latrines , septic tanks and container-based solutions) and specifically

8294-476: Is typically an agricultural anaerobic digester that accepts two or more input materials for simultaneous digestion. The length of time required for anaerobic digestion depends on the chemical complexity of the material. Material rich in easily digestible sugars breaks down quickly, whereas intact lignocellulosic material rich in cellulose and hemicellulose polymers can take much longer to break down. Anaerobic microorganisms are generally unable to break down lignin,

8437-698: Is used as part of the process to treat biodegradable waste and sewage sludge . As part of an integrated waste management system, anaerobic digestion reduces the emission of landfill gas into the atmosphere. Anaerobic digesters can also be fed with purpose-grown energy crops, such as maize . Anaerobic digestion is widely used as a source of renewable energy . The process produces a biogas , consisting of methane , carbon dioxide , and traces of other 'contaminant' gases. This biogas can be used directly as fuel, in combined heat and power gas engines or upgraded to natural gas-quality biomethane . The nutrient-rich digestate also produced can be used as fertilizer . With

8580-496: The "value chain" of fecal sludge management. Fecal sludge is defined very broadly as what accumulates in onsite sanitation technologies and specifically is not transported through a sewer . It is composed of human excreta , but also anything else that may go into an onsite containment technology, such as flushwater, cleansing materials and menstrual hygiene products, grey water (i.e. bathing or kitchen water, including fats, oils and grease), and solid waste . Hence, fecal sludge

8723-625: The Indian context: Achieves the norms through regular desludging, reduces high prices of desludging, removes the need for manual labor, improves environmental and public health impacts, links with local taxes rather than with user charges. Scheduled desludging has been initiated in several Asian counties including the Philippines, Malaysia, Vietnam, Indonesia, and India. A program by SNV (Netherlands Development Organisation) has developed scheduled emptying services in Indonesia, Nepal and Bangladesh as part of

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8866-436: The Philippines, Malaysia, Vietnam, Indonesia, and India. In this process, every property is covered along a defined route and the property occupiers are informed in advance about desludging that will take place. The maintenance of a septic system is often the responsibility of the resident or property owner. Some forms of abuse or neglect include the following: Septic tank additives have been promoted by some manufacturers with

9009-710: The SVVs and actually do the longer haul transferring of the waste from the community to the treatment plant. Mobile transfer stations work best for scheduled desludging programs where there are no traffic restrictions or truck bans, and a relatively large number of homes that are inaccessible to the larger vehicles. Characteristics of fecal sludge may vary widely due to climate, toilet type, diet and other variables. Fecal sludge can be grouped by consistency as "liquid" (total solids or TS <5%), "slurry" (TS 5–15%), "semi-solid" (TS 15–25%), and "solid" (TS >25%). Quantities and qualities of fecal sludge and wastewater are very different, with

9152-607: The Toilet Challenge' since at least 2012. Curriculums have been, and are continuing to be, developed and implemented. Initiatives include the Global Sanitation Graduate School, and freely available online courses, such as the Sandec MOOC series. In many LMICs , fecal sludge is still not properly managed. This may be due to a lack of mandated institutions and low awareness of the impact of poor sanitation;

9295-419: The absence of oxygen . The process is used for industrial or domestic purposes to manage waste or to produce fuels. Much of the fermentation used industrially to produce food and drink products, as well as home fermentation, uses anaerobic digestion. Anaerobic digestion occurs naturally in some soils and in lake and oceanic basin sediments , where it is usually referred to as "anaerobic activity". This

9438-399: The addition of water. The primary styles of dry digesters are continuous vertical plug flow and batch tunnel horizontal digesters. Continuous vertical plug flow digesters are upright, cylindrical tanks where feedstock is continuously fed into the top of the digester, and flows downward by gravity during digestion. In batch tunnel digesters, the feedstock is deposited in tunnel-like chambers with

9581-406: The additional load, and facilities to separate liquids and solids are available. A variety of mechanized and non-mechanized processing technologies may be used, including settling tanks , planted and unplanted drying beds, and waste stabilization ponds . The treatment process can produce resource recovery end-products such as treated effluent that can be used for irrigation , co- composting as

9724-440: The aim to improve the effluent quality from septic tanks, reduce sludge build-up and to reduce odors. These additives—which are commonly based on " effective microorganisms "—are usually costly in the longer term and fail to live up to expectations. It has been estimated that in the U.S. more than 1,200 septic system additives were available on the market in 2011. Very little peer-reviewed and replicated field research exists regarding

9867-399: The anaerobic conditions of septic tanks, are reduced to hydrogen sulfide , a pungent and toxic gas. Nitrates and organic nitrogen compounds can be reduced to ammonia . Because of the anaerobic conditions, fermentation and methanogenesis processes take place, which may generate carbon dioxide and/or methane . Both carbon dioxide and methane are greenhouse gases, with methane having

10010-534: The application of anaerobic digestion as a process for reducing waste volumes and generating useful byproducts. It may either be used to process the source-separated fraction of municipal waste or alternatively combined with mechanical sorting systems, to process residual mixed municipal waste. These facilities are called mechanical biological treatment plants. Fecal sludge Fecal sludge management ( FSM ) (or faecal sludge management in British English)

10153-527: The application of anaerobic digestion systems is the feedstock to the process. Almost any organic material can be processed with anaerobic digestion; however, if biogas production is the aim, the level of putrescibility is the key factor in its successful application. The more putrescible (digestible) the material, the higher the gas yields possible from the system. Feedstocks can include biodegradable waste materials, such as waste paper, grass clippings, leftover food, sewage, and animal waste. Woody wastes are

10296-513: The bacterial groups responsible for the different organic matter degradation steps. The degree of the inhibition depends, among other factors, on the concentration of the inhibitor in the digester. Potential inhibitors are ammonia, sulfide, light metal ions (Na, K, Mg, Ca, Al), heavy metals, some organics (chlorophenols, halogenated aliphatics, N-substituted aromatics, long chain fatty acids), etc. Total ammonia nitrogen (TAN) has been shown to inhibit production of methane. Furthermore, it destabilises

10439-406: The best cases of co-treatment of fecal sludge in wastewater treatment plants. Transfer stations are intermediary drop off locations often used where treatment facilities are located too far away from population centers to make direct disposal feasible. In other locations, traffic concerns or local truck bans during daylight hours may make transfer stations feasible. In addition, municipalities where

10582-450: The biomass is kept in the reactor which is then used for in-vessel composting before it is opened As the batch digestion is simple and requires less equipment and lower levels of design work, it is typically a cheaper form of digestion. Using more than one batch reactor at a plant can ensure constant production of biogas. In continuous digestion processes, organic matter is constantly added (continuous complete mixed) or added in stages to

10725-407: The bottom of the tank, a scum layer that contains fats, oil and grease accumulates at the top, and the effluent or supernatant contains less solids. Septage is periodically removed (with a frequency depending on tank capacity, system efficiency, and usage level, but typically less often than annually) from the septic tanks by specialized vehicles known as vacuum trucks . They pump the septage out of

10868-487: The case of urine-diverting dry toilets ) or compost (in the case of composting toilets ). For example, in the case of Arborloo toilets, nothing is ever extracted from the pit and, instead, the lightweight outhouse superstructure is moved to another shallow hole and a tree is planted on top of the filled hole. FSM services are usually provided by formal and informal private sector service providers, local governments, water authorities and utilities . Water utilities with

11011-591: The chemical reaction, where organic material such as glucose is biochemically digested into carbon dioxide (CO 2 ) and methane (CH 4 ) by the anaerobic microorganisms. C 6 H 12 O 6 → 3CO 2 + 3CH 4 In most cases, biomass is made up of large organic polymers. For the bacteria in anaerobic digesters to access the energy potential of the material, these chains must first be broken down into their smaller constituent parts. These constituent parts, or monomers, such as sugars, are readily available to other bacteria. The process of breaking these chains and dissolving

11154-418: The city. The private sector can also provide services in operating and maintaining the treatment works, and in processing and selling the commodities resulting from the treatment process. San Fernando City, La Union, Philippines is an example of a local government that has contracted out the treatment facility construction and collection program to the private sector. Scheduled desludging is a planned effort by

11297-503: The construction and maintenance of septic systems was introduced in 1992 and updated in 2009 and 2012 with the intent to establish the technical requirements applicable to individual sewerage systems. Septic tanks in France are subject to inspection by SPANC ( Service Public d’Assainissement Non Collectif ), a professional body appointed by the respective local authorities to enforce wastewater collection laws, at least once in four years. Following

11440-444: The costs of building very expensive centralized wastewater treatment systems because of this problem, due to the high cost of extended collection systems. To reduce residential development that might increase the demand to construct an expensive centralized sewerage system, building moratoriums and limitations on the subdivision of property are often imposed. Ensuring existing septic tanks are functioning properly can also be helpful for

11583-559: The country non-compliant with the Waste Framework Directive in relation to domestic wastewaters disposed of in the countryside, the Water Services (Amendment) Act 2012 was passed in order to regulate wastewater discharges from domestic sources that are not connected to the public sewer network and to provide arrangements for registration and inspection of existing individual domestic wastewater treatment systems. Additionally,

11726-573: The design and installation of septic tanks commonly references Australian Standards (1547 and 1546). Capacity requirements for septic tanks may be outlined within Codes of Practice, and can vary between states. Mainly because of water leaching from the effluent drains of a lot of closely spaced septic systems, many council districts (e.g. Sunshine Coast, Queensland ) have banned septic systems, and require them to be replaced with much more expensive small-scale sewage treatment systems that actively pump air into

11869-405: The digestion system. In a typical two-stage mesophilic digestion, residence time varies between 15 and 40 days, while for a single-stage thermophilic digestion, residence times is normally faster and takes around 14 days. The plug-flow nature of some of these systems will mean the full degradation of the material may not have been realised in this timescale. In this event, digestate exiting

12012-601: The direct discharge into surface water is permissible in accordance with a Water Pollution Act license. Registered septic tanks must be desludged by an authorized contractor at least once a year; the removed fecal sludge is disposed of, either to a managed municipal wastewater treatment facility or to agriculture provided that nutrient management regulations are met. Since 2015, only certain property owners in England and Wales with septic tanks or small packaged sewage treatment systems need to register their systems, and either apply for

12155-401: The discharge of digester liquids are a liability. The wetter the material, the more suitable it will be to handling with standard pumps instead of energy-intensive concrete pumps and physical means of movement. Also, the wetter the material, the more volume and area it takes up relative to the levels of gas produced. The moisture content of the target feedstock will also affect what type of system

12298-405: The drain field). Log reductions of 4–8 for coliform bacteria, 0–2 for viruses are achieved in the effluent. Parasitic worm eggs are also removed. Additional filters may be added to improve removal performance although they will need to be replaced periodically. In areas with high population density, groundwater pollution beyond acceptable limits may occur. Some small towns experience

12441-436: The drainage field. Not only is this detrimental for the environment but, if the sludge overflows the septic tank into the leach field, it may clog the leach field piping or decrease the soil porosity itself, requiring expensive repairs. When a septic tank is emptied, the accumulated sludge ( septage , also known as fecal sludge ) is pumped out of the tank by a vacuum truck . How often the septic tank must be emptied depends on

12584-406: The drainage pipe more evenly and extend the drainage field life by preventing premature clogging or bioclogging . An Imhoff tank is a two-stage septic system where the sludge is digested in a separate tank. This avoids mixing digested sludge with incoming sewage. Also, some septic tank designs have a second stage where the effluent from the anaerobic first stage is aerated before it drains into

12727-638: The effective treatment of solids and liquids and the reuse of treated produce where possible. It may include a range of options including on-site and offsite treatment, and the dispersal or capture and further processing of the products of the treatment process into such as biogas , compost and energy. FSM is a critical sanitation service in cities and towns in all countries where households use onsite sanitation systems. Citywide FSM programs may utilize multiple or one treatment facility, use stationary and mobile transfer stations, and engage with micro, small and medium-sized enterprises that may conduct some or all of

12870-531: The efficacy of these biological septic tank additives. While a properly maintained and located septic tank poses no higher amount of environmental problems than centralized municipal sewage treatment, certain problems could arise with a septic tank in an unsuitable location, and septic tank failures are typically more expensive to fix or replace than municipal sewer. Since septic systems require large drainfields , they are unsuitable for densely built areas. Some constituents of wastewater, especially sulfates , under

13013-538: The emission of greenhouse gases in a number of key ways: Anaerobic digestion is particularly suited to organic material, and is commonly used for industrial effluent , wastewater and sewage sludge treatment . Anaerobic digestion, a simple process, can greatly reduce the amount of organic matter which might otherwise be destined to be dumped at sea, dumped in landfills , or burnt in incinerators . Pressure from environmentally related legislation on solid waste disposal methods in developed countries has increased

13156-516: The environment can trigger prolific plant growth including algal blooms, which can also include blooms of potentially toxic cyanobacteria . The soil's capacity to retain phosphorus is usually large enough to handle the load through a normal residential septic tank. An exception occurs when septic drain fields are located in sandy or coarser soils on property adjacent to a water body. Because of limited particle surface area, these soils can become saturated with phosphates. Phosphates will progress beyond

13299-494: The exception, because they are largely unaffected by digestion, as most anaerobes are unable to degrade lignin . Xylophagous anaerobes (lignin consumers) or high temperature pretreatment, such as pyrolysis, can be used to break lignin down. Anaerobic digesters can also be fed with specially grown energy crops , such as silage , for dedicated biogas production. In Germany and continental Europe, these facilities are referred to as "biogas" plants. A codigestion or cofermentation plant

13442-412: The excess water eliminated through percolation into the soil, through evaporation , and by uptake through the root system of plants and eventual transpiration or entering groundwater or surface water . A piping network, often laid in a stone-filled trench (see weeping tile ), distributes the wastewater throughout the field with multiple drainage holes in the network. The size of the drain field

13585-449: The fastest. Commonly known are pH, temperature, salinity etc. but pressure is also one of them. Some species have adapted to life in the deep oceans where pressure is much higher than at sea level. This makes it possible in similar vein as other process parameters such as Temperature, Retention Time, pH to influence the anaerobic digestion process. The anaerobic digestion process can be inhibited by several compounds, affecting one or more of

13728-418: The feedstock mass are potentially convertible to biogas. Low solids (wet) digesters can transport material through the system using standard pumps that require significantly lower energy input. Low solids digesters require a larger amount of land than high solids due to the increased volumes associated with the increased liquid-to-feedstock ratio of the digesters. There are benefits associated with operation in

13871-551: The feedstock material is a key consideration when using wet digestion or plug-flow digestion. If the feedstock to the digesters has significant levels of physical contaminants, such as plastic, glass, or metals, then processing to remove the contaminants will be required for the material to be used. If it is not removed, then the digesters can be blocked and will not function efficiently. This contamination issue does not occur with dry digestion or solid-state anaerobic digestion (SSAD) plants, since SSAD handles dry, stackable biomass with

14014-401: The feedstock, the material is often shredded, minced, and mechanically or hydraulically pulped to increase the surface area available to microbes in the digesters and, hence, increase the speed of digestion. The maceration of solids can be achieved by using a chopper pump to transfer the feedstock material into the airtight digester, where anaerobic treatment takes place. Substrate composition

14157-445: The feedstock. The thickness of the material may also lead to associated problems with abrasion. High solids digesters will typically have a lower land requirement due to the lower volumes associated with the moisture. High solids digesters also require correction of conventional performance calculations (e.g. gas production, retention time, kinetics, etc.) originally based on very dilute sewage digestion concepts, since larger fractions of

14300-426: The first reaction vessel. The organic material is then heated to the required operational temperature (either mesophilic or thermophilic) prior to being pumped into a methanogenic reactor. The initial hydrolysis or acidogenesis tanks prior to the methanogenic reactor can provide a buffer to the rate at which feedstock is added. Some European countries require a degree of elevated heat treatment to kill harmful bacteria in

14443-591: The following benefits: Since the wider recognition of the importance of sanitation, marked by the UN declaring 2008 as the 'Year of Sanitation', there has been a steady increase in commitment, uptake, implementation, and knowledge generation in non-sewered sanitation. The incorporation of the entire sanitation management service chain in the Sustainable Development Goal (SDG) 6 , as opposed to just providing access to toilets, has further established acknowledge of

14586-655: The ground surface, although many of them are still in the experimental stage (e.g. Excravator, Gulper, e-Vac). Fecal sludge can also be treated inside the tank or pit as well, by use of the "in-pit lime stabilization process", which treats the waste before it is removed from the tank or pit. Once removed, it is transported to onsite or off site treatment and processing facilities. Some advanced transfer stations and vacuum trucks can dewater fecal sludge to some extent, and this water may be placed in sewer lines to be treated in wastewater treatment plants. This allows more sludge to be dealt with more efficiently and may constitute one of

14729-464: The importance of FSM. The SDGs were launched in 2015, and SDG 6 is for "clean water and sanitation for all by 2030"), launched in 2015, has further established acknowledgement of its importance. There has also been an increase in the incorporation of fecal sludge management in national regulations and development agency agendas, increased funding from foundations and governments, and implementation of infrastructure and service provision. There has been

14872-414: The input waste. In this instance, there may be a pasteurisation or sterilisation stage prior to digestion or between the two digestion tanks. Notably, it is not possible to completely isolate the different reaction phases, and often some biogas is produced in the hydrolysis or acidogenesis tanks. The residence time in a digester varies with the amount and type of feed material, and with the configuration of

15015-467: The introduction of EN 12566, the discharge of effluent directly into ditches or watercourses is prohibited, unless the effluent meets prescribed standards. According to the Census of Ireland 2011 , 27.5% of Irish households (i.e. about 440,000 households), with the majority in rural areas, use an individual septic tank. Following a European Court of Justice judgment made against Ireland in 2009 that deemed

15158-506: The land.) Failure to properly manage fecal sludge can result in the poor performance of onsite sanitation facilities (OSSFs), fecal sludge overflowing from containments, and the unsafe emptying and dumping of untreated fecal sludge into the environment. Fecal sludge contains pathogens , can generate odors and cause surface water pollution , as well as groundwater pollution . Fecal sludge management (FSM) requires safe and hygienic septic tank and pit latrine emptying services, along with

15301-428: The level of solids in the material, to mix the contents, enabling the bacteria and the food to be in contact. They also allow excess material to be continuously extracted to maintain a reasonably constant volume within the digestion tanks. A recent development in anaerobic reactor design is High-pressure anaerobic digestion (HPAD) also referred to a Autogenerative High Pressure Digestion (AHPD). This technique produces

15444-450: The local government or utility to ensure regular desludging of septic tanks. In this process, every property is covered along a defined route and the property occupiers are informed in advance about desludging that will take place. The actual desludging (or emptying of septic tanks) can be done through a public private partnership (PPP) arrangement. In Southeast Asia, there is (in 2016) increasing interest in scheduled desludging programs as

15587-475: The market. After sitting for years in septic tanks and pit latrines, the accumulated sludge becomes hardened and is very difficult to remove. It is still common that workers enter pits in order to desludge them, even though this practice is generally unsafe and undesirable (in India, this practice is called " manual scavenging "). A number of low-cost pumping systems exist to remove this hardened sludge hygienically from

15730-415: The microbial community, impacting the synthesis of acetic acid. Acetic acid is one of the driving forces in methane production. At an excess of 5000 mg/L TAN, pH adjustment is needed to keep the reaction stable. A TAN concentration above 1700– 1800 mg/L inhibits methane production and yield decreases at greater TAN concentrations. High TAN concentrations cause the reaction to turn acidic and lead to

15873-444: The municipality that serve as drop off locations for collected fecal sludge. They may include a receiving station with screens, a tank for holding the collected waste, trash storage containers, and wash down facilities. These may be more appropriate for FSM programs using the "call-for-service" business model. While static transfer stations are fixed tanks, mobile transfer stations are simply tanker trucks or trailers that work alongside

16016-411: The organic material itself, the 'intermediate' end products are primarily alcohols , aldehydes , and organic acids, plus carbon dioxide. In the presence of specialised methanogens, the intermediates are converted to the 'final' end products of methane, carbon dioxide, and trace levels of hydrogen sulfide . In an anaerobic system, the majority of the chemical energy contained within the starting material

16159-413: The organic matter has completed. There can be severe odour issues if a batch reactor is opened and emptied before the process is well completed. A more advanced type of batch approach has limited the odour issues by integrating anaerobic digestion with in-vessel composting . In this approach inoculation takes place through the use of recirculated degasified percolate. After anaerobic digestion has completed,

16302-578: The overwhelming majority of systems are located in rural (50%) and suburban (47%) areas. Indianapolis is one example of a large city where many of the city's neighborhoods still rely on separate septic systems. In Europe, septic systems are generally limited to rural areas. In the European Union the EN 12566 standard provides the general requirements for packaged and site assembled treatment plants used for domestic wastewater treatment. Part 1 ( EN 12566-1 )

16445-565: The pathogenic concentration in the digestate, leaving the anaerobic digester. Pasteurisation may be achieved by heat treatment combined with maceration of the solids. In a typical scenario, three different operational parameters are associated with the solids content of the feedstock to the digesters: High solids (dry) digesters are designed to process materials with a solids content between 25 and 40%. Unlike wet digesters that process pumpable slurries, high solids (dry – stackable substrate) digesters are designed to process solid substrates without

16588-456: The pollution sources that threaten shellfish growing waters. The term "septic tank", or more usually "septic", is used in some parts of Britain as a slang term to refer to Americans, from Cockney rhyming slang septic tank equalling yank. This is sometimes further shortened to "seppo" by Australians . Anaerobic digestion Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in

16731-437: The preceding stages and convert them into methane, carbon dioxide, and water. These components make up the majority of the biogas emitted from the system. Methanogenesis is sensitive to both high and low pHs and occurs between pH 6.5 and pH 8. The remaining, indigestible material the microbes cannot use and any dead bacterial remains constitute the digestate. Anaerobic digesters can be designed and engineered to operate using

16874-427: The prediction include income level, users, volume, emptying frequency, and truck size. Using these correlations in characteristics could provide a way to reduce analytical costs for fecal sludge analysis. Performing a waste characterization study helps to understand local conditions and provides data that factors into treatment plant sizing. It can also help to estimate the value of the products that can be derived from

17017-425: The protection of public health . FSM services are provided by a range of formal and informal private sector services providers, local governments, water authorities, and public utilities . This can also result in unreliable services with relatively high costs at the household level. Although new technology now allows for fecal sludge to be treated onsite (see Mobile Treatment Units below) the majority of fecal sludge

17160-430: The range of fecal sludge characteristics being 1–2 orders of magnitude higher than wastewater. The result of the demographic, environmental, and technical factors that influence characteristics of fecal sludge is a high level of heterogeneity that complicates characterization. In the absence of actual data, designers often use default values, such as 2,000 mg/L for BOD and 5,000 mg/L of TSS in order to size

17303-408: The rate of decomposition. Therefore, the accumulated fecal sludge must be periodically removed, which is commonly done with a vacuum truck . A septic tank consists of one or more concrete or plastic tanks of between 4,500 and 7,500 litres (1,000 and 2,000 gallons); one end is connected to an inlet wastewater pipe and the other to a septic drain field . Generally these pipe connections are made with

17446-594: The re-use of waste as a resource and new technological approaches that have lowered capital costs , anaerobic digestion has in recent years received increased attention among governments in a number of countries, among these the United Kingdom (2011), Germany, Denmark (2011), and the United States. Many microorganisms affect anaerobic digestion, including acetic acid-forming bacteria ( acetogens ) and methane-forming archaea ( methanogens ). These organisms promote

17589-507: The reactor (continuous plug flow ; first in – first out). Here, the end products are constantly or periodically removed, resulting in constant production of biogas. A single or multiple digesters in sequence may be used. Examples of this form of anaerobic digestion include continuous stirred-tank reactors , upflow anaerobic sludge blankets , expanded granular sludge beds , and internal circulation reactors . The two conventional operational temperature levels for anaerobic digesters determine

17732-458: The recalcitrant aromatic component of biomass. Anaerobic digesters were originally designed for operation using sewage sludge and manures. Sewage and manure are not, however, the material with the most potential for anaerobic digestion, as the biodegradable material has already had much of the energy content taken out by the animals that produced it. Therefore, many digesters operate with codigestion of two or more types of feedstock. For example, in

17875-479: The seepage field. A properly designed and normally operating septic system is odour-free. Besides periodic inspection and emptying, a septic tank should last for decades with minimal maintenance, with concrete, fibreglass, or plastic tanks lasting about 50 years. Waste that is not decomposed by the anaerobic digestion must eventually be removed from the septic tank. Otherwise the septic tank fills up and wastewater containing undecomposed material discharges directly to

18018-464: The service more cheaply and more hygienically than the independent private operators working on an ad hoc basis. Ensuring services are affordable is an important selling point when promoting the program to citizens and encouraging them to participate. The local private sector is an important player in providing FSM services. In such cases, private sector contractors may work directly for households (under regulation) or bid on desludging contracts let by

18161-458: The services. Programs may be phased in over time to accommodate growing demand. Peri urban areas are often less densely populated than urban centers. Therefore, they have more space and on-site sanitation systems can be effective for solid and liquid treatment. In most such peri-urban areas, it is less likely that they will be connected to a conventional centralized sewerage system in the short or medium term. Therefore, these areas will rely on

18304-452: The smaller molecules into solution is called hydrolysis. Therefore, hydrolysis of these high-molecular-weight polymeric components is the necessary first step in anaerobic digestion. Through hydrolysis the complex organic molecules are broken down into simple sugars , amino acids, and fatty acids . Acetate and hydrogen produced in the first stages can be used directly by methanogens. Other molecules, such as volatile fatty acids (VFAs) with

18447-454: The species of methanogens in the digesters: A limit case has been reached in Bolivia , with anaerobic digestion in temperature working conditions of less than 10 °C. The anaerobic process is very slow, taking more than three times the normal mesophilic time process. In experimental work at University of Alaska Fairbanks , a 1,000-litre digester using psychrophiles harvested from "mud from

18590-439: The stacked pile. Continuous vertical dry digesters have a smaller footprint due to the shorter effective retention time and vertical design. Wet digesters can be designed to operate in either a high-solids content, with a total suspended solids (TSS) concentration greater than ~20%, or a low-solids concentration less than ~15%. High solids (wet) digesters process a thick slurry that requires more energy input to move and process

18733-400: The start of the process. The reactor is then sealed for the duration of the process. In its simplest form batch processing needs inoculation with already processed material to start the anaerobic digestion. In a typical scenario, biogas production will be formed with a normal distribution pattern over time. Operators can use this fact to determine when they believe the process of digestion of

18876-552: The substrate that is converted to biogas in a reactor). In order to predict biogas composition (the relative fractions of methane and carbon dioxide) it is necessary to estimate carbon dioxide partitioning between the aqueous and gas phases, which requires additional information (reactor temperature, pH , and substrate composition) and a chemical speciation model. Direct measurements of biomethanation potential are also made using gas evolution or more recent gravimetric assays. Using anaerobic digestion technologies can help to reduce

19019-448: The system will be darker in colour and will typically have more odour. In the case of an upflow anaerobic sludge blanket digestion (UASB), hydraulic residence times can be as short as 1 hour to 1 day, and solid retention times can be up to 90 days. In this manner, a UASB system is able to separate solids and hydraulic retention times with the use of a sludge blanket. Continuous digesters have mechanical or hydraulic devices, depending on

19162-399: The system. Additionally, their structural adequacy in relevant ground conditions is assessed in terms of water-tightness, treatment efficiency, and structural behaviour. In France , about 4 million households (or 20% of the population) are using on-site wastewater disposal systems ( l’assainissement non collectif ), including septic tanks ( fosse septique ). The legal framework for regulating

19305-494: The tank and clog the clarified liquid effluent disposal system. In Washington , for example, a "shellfish protection district" or "clean water district" is a geographic service area designated by a county to protect water quality and tideland resources. The district provides a mechanism to generate local funds for water quality services to control non-point sources of pollution, such as septic system maintenance. The district also serves as an educational resource, calling attention to

19448-649: The tank, and transport it to a local fecal sludge treatment plant. It can also be used by farmers for fertilizer, or stored in large septage waste storage facilities for later treatment or use on crops. The term "septage" has been used in the United States since at least 1992. It has also been used in projects by the United States Agency for International Development in Asia. Another definition of septage is: "A historical term to define sludge removed from septic tanks." In India some government policy documents are using

19591-492: The tank, producing an aerobic environment. Septic systems have to be replaced as part of any new building applications, regardless of how well the old system performed. According to the US Environmental Protection Agency , in the United States it is the home owners' responsibility to maintain their septic systems. Anyone who ignores this requirement will eventually experience costly repairs when solids escape

19734-506: The term FSSM for "Fecal sludge and septage management". The overall goal of FSM is the protection of public and environmental health. FSM forms a key component of city-wide inclusive sanitation (CWIS), which considers all types of sanitation technologies in order to provide equitable, safe, and sustainable sanitation for everyone. CWIS employs a service delivery approach along the entire service chain, rather than just infrastructure provision. Adequately and safely managed fecal sludge has

19877-411: The treatment area, posing a threat of eutrophication to surface waters. Diseases extremely dangerous to human contact such as E. coli and other coliform bacteria are often reported following failures of septic tanks. A properly functioning septic system, on the other hand, provides significant reduction of pathogens compared to direct discharge due to settling (in the tank) and soil absorption (in

20020-568: The treatment process. The main physico-chemical parameters commonly measured to characterize fecal sludge include: BOD , total suspended solids , % solids, indication of sand, COD , ammonium , total nitrogen and total phosphorus, Fats, Oil and Grease (FOG), Sludge Volume Index (SVI), pH, alkalinity . Relatively little data exists on pathogen content in fecal sludge. One study from rural Bangladesh determined 41 helminth eggs per g of fecal sludge from pit latrines. The characteristics of fecal sludge may be influenced by: Fecal Sludge

20163-454: The treatment system. However, this often results in over-design or under-design of fecal sludge treatment plants. This is because there is often no "standard range of variation" for particular properties, and findings from one study cannot necessarily be used as a base of comparison to another. Research has shown that correlations to spatially available data can help predict quantities and qualities of fecal sludge. The relevant indicators for

20306-416: The volume of solids. The liquid component flows through the dividing wall into the second chamber, where further settlement takes place. One option for the effluent is the draining into the septic drain field , also referred to as a leach field, drain field or seepage field, depending upon locality. A percolation test is required prior to installation to ensure the porosity of the soil is adequate to serve as

20449-583: The volume of the tank relative to the input of solids, the amount of indigestible solids, and the ambient temperature (because anaerobic digestion occurs more efficiently at higher temperatures), as well as usage, system characteristics and the requirements of the relevant authority. Some health authorities require tanks to be emptied at prescribed intervals, while others leave it up to the decision of an inspector. Some systems require pumping every few years or sooner, while others may be able to go 10–20 years between pumpings. An older system with an undersize tank that

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