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<!{|style="float: left;"|{{Language-box|english_link=Solids- table at top of page with logo, picture, Application level, Management level, and input-output tables -->free_Sewer|french_link=Réseau_d’égout_simplifié_sans_matières_solides|spanish_link=Alcantarillados_Libres_de_Solidos|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 SewerageEffluent Transport|67]]|

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'''A Solidssolids-Free Sewer free sewer is a network of small -diameter pipes that transports pre-treated and solids-free or pre-treated wastewater (such as [[Septic Tank]] or settling tank effluent) to . It can be installed at a shallow depth and does not require a treatment facility for further treatment minimum wastewater flow or slope to a discharge point. Solids-Free Sewers are also referred to as settled, small-bore, small-diameter, variable-grade gravity, or septic tank effluent gravity sewersfunction.'''

<br>Solids-free sewers are also referred to as settled, smallbore, variable-grade gravity, or septic tank effluent gravity sewers. A precondition for Solidssolids-Free Sewer networks free sewers is efficient pre-primary treatment at the household level. The An interceptor, septic or settling tank removes typically a single-chamber [[Septic Tank]] (S.9), captures settleable particles that could clog small pipes. A grease trap should The solids interceptor also be addedfunctions to attenuate peak discharges. Because there is little risk of depositions and clogging, the solids-free sewers do not have to be self-cleaning (cleansing, i.e. , no minimum flow velocity) and can therefore be laid at shallow depths, can have fewer or tractive tension is needed. They require few inspection points (manholes), can follow the topography more closely and have inflective gradients (i.e. , negative slopeslopes)and follow the topography. When the sewer roughly follows the ground contours, the flow in the sewer is allowed to vary between open channel flow and pressure (full-bore) flow. However, care should be taken with negative slopes as they may lead to surging above the ground level during peak flows. Inspection points should be provided at major connection points or when the size of the pipe changes.

Despite ===Design Considerations=== If the possibility that some portions interceptors are correctly designed and operated, this type of the pipe can rise higher when going downstreamsewer does not require self-cleansing velocities or minimum slopes. Even inflective gradients are possible, for the total pipe as long as the downstream end of the sewer must be is lower than the upstream end. When choosing a pipe diameter (at least 75mm), the depth of water in the pipe during peak flow within each section must be less than the diameter of the pipe. In sections where there is pressure flow, the invert of water level in any interceptor tank outlet must be higher than the hydraulic head within the sewer just prior to the point of connection , otherwise the liquid will backflow flow back into the tank. If this condition is not metAt high points in sections with pressure flow, then either select the next larger pipe diameter for the sewer or increase the depth at which the sewer is laidpipes must be ventilated.

{{procontable | pro=Solids- Greywater can free sewers do not have to be managed at the same timeinstalled on a uniform gradient with a straight alignment between inspection points. <br> - Can be built and repaired with locally available materialsThe alignment may curve to avoid obstacles, allowing for greater construction tolerance. <br> - Construction can provide short-term employment A minimum diameter of 75 mm is required to local labourersfacilitate cleaning. <br> - Capital costs Expensive manholes are less than [[Conventional Gravity Sewer|Conventional Gravity Sewers]]; low operating costsnot needed because access for mechanical cleaning equipment is not necessary. <br> - Can be extended as a community Cleanouts or flushing points are sufficient and are installed at upstream ends, high points, intersections, or major changes and growsin direction or pipe size. | con=- Requires expert design and construction supervision. <br> - Requires repairs and removals of blockages Compared to manholes, cleanouts can be more frequently than a Conventional Gravity Sewer. <br> - Requires education and acceptance tightly sealed to be used correctly. <br> - Effluent and sludge (prevent stormwater from interceptors) requires secondary treatment and/or appropriate discharge.<br>-High water consumption for excreta removalentering. }}

==Adequacy=<br>{{procontable | pro=- Does not require a minimum gradient or flow velocity <br>Solids-Free Sewers are appropriate for both full and partially filled flows. Although a constant Can be used where water supply of water is required, less water is needed compared to the Simple Sewer because selflimited <br>-cleansing velocities are not required.Lower capital costs than conventional gravity sewers; low operating costs <br>[[Septic Tank|Septic Tanks]] and Solids-Free Sewers can Can be built for new areas, or extended as a Solidscommunity grows <br>-Free Sewer Greywater can be connected to an existing primary treatment technology where local infiltration is inappropriate. A Solids-Free Sewer can be built for 20% to 50% less than [[Conventional Gravity Sewermanaged concurrently|Conventional Gravity Sewerage]].con= This technology must be connected to an appropriate [[(Semi-) Centralized Treatment System|(Semi-) Centralized Treatment technology]] that can receive the wastewater. It is appropriate Space for densely populated areas where there interceptors is no space for a [[Soak Pit]] or [[Leach Field]]. This type of sewer is best suited required <br>- Interceptors require regular desludging to urban prevent clogging <br>- Requires training and less appropriate in lowacceptance to be used correctly <br>-density or rural areas. ==Health Aspects/Acceptance== This technology requires regular maintenance on the part of the users Requires repairs and is therefore, not as passive as [[Conventional Gravity Sewer|Conventional Gravity Sewers]]. Users must assume some level removals of responsibility for the technology blockages more frequently than a conventional gravity sewer <br>- Requires expert design and accept that some potentially unpleasant maintenance may be required. Also, users should be aware that, because the system is community based, they may have to work with and/or coordinate maintenance activities with other users. The system will provide construction <br>- Leakages pose a high level risk of service wastewater exfiltration and may offer a significant improvement groundwater infiltration and are difficult to non-functioning [[Leach Field|Leach Fields]].identify==Upgrading== Solids-Free Sewers are good upgrading options for [[Leach Field|Leach Fields]] that have become clogged and/or saturated with time as well as for rapidly growing areas that would not accommodate more [[Septic Tank|Septic Tanks]] with Leach Fields.}}

==Maintenance=Appropriateness=== This type of sewer is best suited to medium-density (peri-)urban areas and less appropriate in low-density or rural settings. It is most appropriate where there is no space for a [[Leach Field]] (D.8), or where effluents cannot otherwise be disposed of onsite (e.g., due to low infiltration capacity or high groundwater). It is also suitable where there is undulating terrain or rocky soil. A solids-free sewer can be connected to existing Septic Tanks where infiltration is no longer appropriate (e.g., due to increased housing density and/or water use).

The septic/interceptor tank must be regularly maintained and desludged As opposed to insure optimal performance of the Solids-Free a [[Simplified Sewer network]] (C. If the pre4) a solids-treatment free sewer can also be used where domestic water consumptionis limited. This technology is efficient, a flexible option that can be easily extended as the risk population grows. Because of clogging in shallowexcavations and the pipes is lowuse of fewer materials, but some maintenance will it can be required periodicallybuilt at considerably lower cost than a [[Conventional Gravity Sewer | Conventional Sewer]] (C. The sewers should be flushed once a year as part of the regular maintenance regardless of their performance6).

==References=Upgrading===Solids-Free Sewers are good upgrading options for Leach Fields that have become clogged and/or saturated with time as well as for rapidly growing areas that would not accommodate more Septic Tanks with Leach Fields.

===References===* Elizabeth Tilley etAzevedo Netto, J. and Reid, R.al (20081992). [httphttps://www.eawagircwash.ch/organisation/abteilungen/sandecorg/publikationensites/publications_sespdefault/downloads_sespfiles/compendium_high332-92IN-9897.pdf Compendium of Sanitation Systems Innovative and Low- Cost TechnologiesUtilized in Sewerage] ([http://www.eawagTechnical Series No. 29, Environmental Health Program, Pan American Health Organization, Washington, D.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_lowC.pdf low res version]), US. Department of Water and Sanitation in Development Countries ([http://www.sandec.ch/ Sandec]) at the Swiss Federal Institute of Aquatic Science A short summary and Technology (Eawag). (Provides a full overview of sanitation systems.component diagrams – Chapter 5)

* Azevedo NettoCrites, MMR. and ReidTchobanoglous, RG. (19921998). Innovative Small and Low Cost Technologies Utilized in SewerageDecentralized Wastewater Management Systems. Environmental Health ProgramWCB/McGraw- Hill, New York, Technical Series NoUS. 29pp. Pan American Health Organization, Washington DC355-364. (Book; A Short short summary of design and component diagrams-Chapter 5.construction considerations)

* CritesMara, RD. and Tchobanoglous, GD. (19981996a). Small and Decentralized Wastewater Management Systems[https://www.susana. WCB org/en/knowledge-hub/resources-and McGraw-Hillpublications/library/details/2972 Low-Cost Sewerage]. Wiley, New YorkChichester, USA. pp 355–364UK. (A short summary Assessment of design different low-cost systems and construction considerations.case studies)

* Mara, DDD. D. (19961996b). Low-Cost SewerageUrban Sanitation. Wiley, ChicheserChichester, UK. (Assessment of different lowpp. 93-cost systems and case studies108.(Book; Comprehensive summary including design examples)

* Otis, R. J. and Mara, DDD. D. (19961985). Low[https://www.ircwash.org/resources/design-Cost Urban Sanitationsmall-bore-sewer-systems The Design of Small Bore Sewer Systems]. WileyUNDP Interregional Project INT/81/047, The World Bank and UNDP, ChichesterWashington, UKD. pp 93–108C., US. (Comprehensive summary including of design examples., installation and maintenance)

* Otis, RJ. and Mara, DD. (1985). The Design of Small Bore Sewer Systems (UNDP Interreg. Project INT/81/047). TAG Technical Note No.14. United Nations Development Programme + World Bank, Washington. Available===Acknowledgements==={{: www.wds.worldbank.org (Comprehensive summary of design, installation and maintenance.)Acknowledgements Sanitation}}