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<!{|style="float: left;"|{{Language-- table at top of page with logo, picture, Application level, Management level, and input-output tables -->box|english_link=Anaerobic_Filter|french_link=Filtre_Anaérobie|spanish_link=Filtro_Anaerobico|hindi_link=coming soon|malayalam_link=coming soon|tamil_link=coming soon | korean_link=coming soon chinese_link=Coming soon | indonesian_link=Coming soon | japanese_link=Coming soon }}|}{|width="100%"|style="width:50%;"|{{santablesantable_new|sys1=[[Blackwater Treatment System with Infiltration|56]]|sys2=[[Blackwater Treatment System with SewerageEffluent Transport|67]]|

ApplHousehold=XXX|

ManHousehold=XXX|

Input1=Blackwater|Input2=GreywaterBrownwater|Input3=Greywater| Input4= |Input5=|Output1=Faecal SludgeEffluent|Output2=Effluent Sludge | Output3= | Output4= | Output5=

'''An Anaerobic Filter is a fixed-bed biological reactor. As wastewater flows through the filter<br>With this technology, particles are trapped suspended solids and organic matter BOD removal can be as high as 90%, but is degraded by the biomass that typically between 50% and 80%. Nitrogen removal is attached to the filter materiallimited and normally does not exceed 15% in terms of total nitrogen (TN).'''

This technology consists ===Design Considerations=== Pre- and primary treatment is essential to remove solids and garbage that may clog the filter. The majority of settleable solids are removed in a sedimentation tank chamber in front of the anaerobic filter. Small-scale, stand-alone units typically have an integrated settling compartment, but primary sedimentation can also take place in a separate [[Settler]] (T.1) or another preceding technology (e.g., existing [[Septic Tank]]s) followed by one or more filter chambers. Filter material commonly used includes gravel, crushed rocks, cinder, or specially formed plastic pieces. Typical filter material sizes range from 12 to 55mm Designs without a settling compartment (as shown in diameterT. Ideally, the material will provide between 90 to 300m2 of surface area per 1m3 4) are of reactor volume. By providing a large surface area particular interest for (Semi-) Centralized Treatment plants that combine the bacterial massanaerobic filter with other technologies, there is increased contact between such as the organic matter and the active biomass that effectively degrades it[[Anaerobic Baffled Reactor (ABR)| Anaerobic Baffled Reactor (ABR)]] (ABR, T.3).

The Anaerobic Filter can be filters are usually operated in either upflow or downflow mode. The upflow mode is recommended because there is less risk that the fixed biomass will be washed out. The water level should cover the filter media by at least 0.3m 3 m to guarantee an even flow regime. Studies have shown that the The hydraulic retention time (HRT ) is the most important design parameter influencing filter performance. An HRT of 0.5 12 to 1.5 days 36 hours is a typical and recommended. A maximum The ideal filter should have a large surface-loading (iarea for bacteria to grow, with pores large enough to prevent clogging.eThe surface area ensures increased contact between the organic matter and the attached biomass that effectively degrades it. flow Ideally, the material should provide between 90 to 300 m2 of surface area per area) rate m3 of 2occupied reactor volume.8m/d has proven Typical filter material sizes range from 12 to be suitable55 mm in diameter. Suspended solids and BOD removal can be as high as 85% to 90% but is typically between 50% and 80%. Nitrogen removal is limited and normally does not exceed 15% in terms of total nitrogen (TN)Materials commonly used include gravel, crushed rocks or bricks, cinder, pumice, or specially formed plastic pieces, depending on local availability.

- Resistant to organic and hydraulic shock loads. <br> - No electrical energy is required. <br> - Can be built and repaired with locally available materials. Low operating costs <br> - Long service life. <br> - High reduction of BOD and solids <br>- Low sludge production; the sludge is stabilized <br>- Moderate capital costs, moderate operating costs depending on emptying; area requirement (can be lowered depending on number of users. built underground) <br> - High reduction of BOD and solids. | con=- Requires constant source expert design and construction <br>- Low reduction of water. pathogens and nutrients <br> - Effluent and sludge require secondary further treatment and/or appropriate discharge. <br> - Low reduction Risk of pathogens clogging, depending on pre- and nutrients. primary treatment <br> - Requires expert design Removing and construction. <br> - Long start up time.cleaning the clogged filter media is cumbersome

==Adequacy== This technology is easily adaptable and can suitable for areas where land may be applied at limited since the household level or tank is most commonly installed underground and requires a small neighbourhood (refer to Technology Information Sheet T2: Anaerobic Filter for information about applying an Anaerobic Filter at the community level)area. An Anaerobic Filter can be designed for a single house or a group of houses that are using a lot of water for clothes washing, showering, and toilet flushing. It Accessibility by vacuum truck is only appropriate if water use is high, ensuring that the supply of wastewater is constant. The Anaerobic Filter will not operate at full capacity important for six to nine months after installation because of the long start up time required for the anaerobic biomass to stabilizedesludging. Therefore, the Anaerobic Filter technology should not be used when the need for a treatment technology is immediate. Once working at full capacity it is a stable technology that requires little attention. The Anaerobic Filter should be watertight but it should still not be constructed in areas with high groundwater tables or where there is frequent flooding. Depending on land availability and the hydraulic gradient of the sewer (if applicable), the Anaerobic Filter can be built above or below ground. It filters can be installed in every type of climate, although the efficiency will be affected is lower in colder climates. ==Health Aspects/Acceptance== Because the Anaerobic Filter unit is underground, users do not come in contact with the influent or effluent. Infectious organisms They are not sufficiently removed, so the effluent should be further treated or discharged properly. The effluent, despite treatment, will still have a strong odour and care should be taken to design efficient at removing nutrients and locate the facility such that odours do not bother community memberspathogens. To prevent the release of potentially harmful gases, the Anaerobic Filters should be vented. The desludging of the filter is hazardous and appropriate safety precautions should be taken. ==Maintenance== Active bacteria must be added to start up the Anaerobic Filter. The active bacteria can come from sludge from a septic tank that has been sprayed onto Depending on the filter material. The flow should be gradually increased over time, and the filter should be working at maximum capacity within six to nine months. With time, the solids will clog the pores of the filter. As wellhowever, the growing bacterial mass will become too thick and will break off and clog pores. A sedimentation tank before the filter is required to prevent the majority of settleable solids from entering the unit. Some clogging increases the ability of the filter to retain solids. When the efficiency complete removal of the filter decreases, it must worm eggs may be cleanedachieved. Running the system in reverse mode to dislodge accumulated biomass and particles cleans the filters. Alternatively, the filter material can be removed and cleanedThe effluent usually requires further treatment. 

==References=Health Aspects/Acceptance=== Under normal operating conditions, users do not come in contact with the influent or effluent. Effluent, scum and sludge must be handled with care as they contain high levels of pathogenic organisms. The effluent contains odorous compounds that may have to be removed in a further polishing step. Care should be taken to design and locate the facility such that odours do not bother communitymembers.

* Elizabeth Tilley et===Operation & Maintenance=== An anaerobic filter requires a start-up period of 6 to 9 months to reach full treatment capacity since the slow growing anaerobic biomass first needs to be established on the filter media.al (2008)To reduce startup time, the filter can be inoculated with anaerobic bacteria, e. [http://wwwg.eawag, by spraying Septic Tank sludge onto the filter material.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_highThe flow should be gradually increased over time.pdf Compendium Because of Sanitation Systems and Technologies] ([http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_low.pdf low res version]). Department of Water and Sanitation in Development Countries ([http://www.sandec.ch/ Sandec]) at the Swiss Federal Institute of Aquatic Science and Technology (Eawag). (Provides a full overview of sanitation systemsdelicate ecology, care should be taken not to discharge harsh chemicals into the anaerobic filter.)

* MorelScum and sludge levels need to be monitored to ensure that the tank is functioning well. Over time, Asolids will clog the pores of the filter. As well, the growing bacterial mass will become too thick, break off and Dienereventually clog pores. When the efficiency decreases, Sthe filter must be cleaned. This is done by running the system in reverse mode (2006backwashing). Greywater Management in Low and Middle-Income Countries, Review of different treatment systems for households or neighbourhoods. Swiss Federal Institute of Aquatic Science by removing and Technology (Eawag), Dübendorf, Switzerlandcleaning the filter material. (Short summary including case studies, page 28Anaerobic filter tanks should be checked from time to time to ensure that they are watertight.)

===References===* PolprasertMorel, CA. and RajputDiener, VSS. (19822006). Environmental Sanitation Reviews[https: Septic Tank //www.susana.org/_resources/documents/default/2-947-en-greywater-management-2006.pdf Greywater Management in Low and Septic Middle-Income Countries]. Review of Different Treatment Systemsfor Households or Neighbourhoods. Environmental Sanitation Information CenterEawag (Department Sandec), AITDübendorf, Bangkok, ThailandCH. pp 68–74. (Short design summary.)

* Sassevon Sperling, LM. and de Lemos Chernicharo, C. A. (19982005). DEWATS[https: Decentralised //www.iwapublishing.com/sites/default/files/ebooks/9781780402734.pdf Biological Wastewater Treatment in Developing CountriesWarm Climate Regions, Volume One]. BORDAIWA Publishing, Bremen Overseas Research and Development AssociationLondon, Bremen, GermanyUK. pp. (Design summary including Excel728-based design program804.)

* von SperlinUlrich, MA. (Ed.), Reuter, S. (Ed.), Gutterer, B. (Ed.), Sasse, L., Panzerbieter, T. and de Lemos ChernicharoReckerzügel, CAT. (20052009). Biological [https://wedc-knowledge.lboro.ac.uk/resources/books/DEWATS_-_Chapter_01.pdf Decentralised Wastewater Treatment Systems (DEWATS) and Sanitation in Warm Climate RegionsDeveloping Countries. Volume OneA Practical Guide]. IWAWEDC, Loughborough University, Leicestershire, London. pp 728–804UK. (Detailed Design summary including Excel spreadsheets for design instructions.calculations)

* Vigneswaran, S., et al. (1986). Environmental Sanitation Reviews===Acknowledgements==={{: Anaerobic Wastewater Treatment-Attached growth and Sludge blanket process. Environmental Acknowledgements Sanitation Information Center, AIT Bangkok, Thailand. (Design criteria and diagrams in Chapter 2.)}}