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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=Activated_Sludge|french_link=Boues_activés|spanish_link=Lodo_Activado|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|

sys2=[[Blackwater Treatment System with Infiltration|56]]|sys3=[[Blackwater Treatment System with SewerageEffluent Transport|67]]|sys4=[[Blackwater Transport to (Semi-) Centralized Treatment System |78]]|sys5=[[Sewerage System with Urine Diversion|9]]|

Input1=Blackwater|Input2=Greywater |Input3= Brownwater | Input4= Effluent |Input5=|Output1= Effluent | Output2= Treated Sludge | Output3= | Output4= | Output5=|english_link=Activated_Sludge|french_link=Boues_activés|spanish_link=Lodo_Activado

[[Image:Icon_activated_sludge.png |right|95px80px]]'''Activated Sludge is a multi-chamber reactor unit that makes use of (mostly) aerobic microorganisms to degrade organics in wastewater and to produce a high-quality effluent. To maintain aerobic conditions and to the keep the active biomass suspended, a constant and well-timed supply of oxygen is required.'''

Different configurations of the Activated Sludge '''An activated sludge process can be employed refers to ensure a multi-chamber reactor unit that the wastewater is mixed makes use of highly concentrated microorganisms to degrade organics and aerated (with either air or pure oxygen) in an aeration tank. The microorganisms oxidize the organic carbon in the remove nutrients from wastewater to produce new cells, carbon dioxide and watera high-quality effluent. Although aerobic bacteria are the most common organisms, To maintain aerobic, anaerobic, conditions and/or nitrifying bacteria along with higher organisms can be present. The exact composition depends on to keep the reactor designactivated sludge suspended, environment, and wastewater characteristics. During aeration and mixing, the bacteria form small clusters, or flocs. When the aeration stops, the mixture is transferred to a secondary clarifier where the flocs are allowed to settle out continuous and the effluent moves on for further treatment or discharge. The sludge is then recycled back to the aeration tank, where the process well-timed supply of oxygen is repeatedrequired.'''

To achieve specific effluent goals for BOD, nitrogen <br>Different configurations of the activated sludge process can be employed to ensure that the wastewater is mixed and phosphorus, different adaptations aerated in an aeration tank. Aeration and modifications have been made to mixing can be provided by pumping air or oxygen into the basic Activated Sludge designtank or by using surface aerators. Aerobic conditionsThe microorganisms oxidize the organic carbon in the wastewater to produce new cells, nutrient-specific carbon dioxide and water. Although aerobic bacteria are the most common organisms (especially for phosphorus), recycle design and carbon dosing, among others, have successfully allowed Activated Sludge processes to achieve high treatment efficienciesfacultative bacteria along with higher organisms can be present.

- Good resistance against Resistant to organic and hydraulic shock loading. loads <br> - Can be operated at a range of organic and hydraulic loading rates. <br>- High reduction of BOD and pathogens (up to 99%). <br> - High nutrient removal possible <br>- Can be modified to meet specific discharge limits. | con=- High energy consumption, a constant source of electricity is required <br>- High capital and operating costs <br>- Requires operation and maintenance by skilled personnel <br>- Prone to complicated chemical and microbiological problems. <br> - Effluent might require further treatment/ disinfection before discharge. <br> - Not all parts and materials may be locally available locally. <br> - Requires expert design and supervision. <br> - High Capital cost; high operation cost. construction <br> - Constant source of electricity is required. <br> - Effluent Sludge and sludge possibly effluent require secondary further treatment and/or appropriate discharge.

==Adequacy=Appropriateness=== Activated Sludge An activated sludge process is only appropriate for a centralized treatment Centralized Treatment facility with a well-trained staff, constant electricity and a highly developed centralized management system to ensure that ensures that the facility is correctly operated and maintained correctly. Activated Sludge processes are one part Because of economies of a complex treatment system. They are used following primary treatment (that removes settleable solids) scale and before a final polishing step. The biological processes that occur are effective at removing solubleless fluctuating influent characteristics, colloidal and particulate organic materials for biological nitrification and denitrification and for biological phosphorus removal. This this technology is more effective for the treatment of large volumes of flows: 10. An activated sludge process is appropriate in almost every climate. However,000 to 1,000,000 peopletreatment capacity is reduced in colder environments.

Highly trained staff ===Health Aspects/Acceptance=== Because of space requirements and odours, Centralized Treatment facilities are generally located in the periphery of densely populated areas. Although the effluent produced is required for maintenance of high quality, it still poses a health risk and trouble-shootingshould not be directly handled. The design must be based on an accurate estimation of In the wastewater composition and volumeexcess sludge pathogens are substantially reduced, but not eliminated.

Treatment efficiency can ===Operation & Maintenance=== Highly trained staff is required for maintenance and troubleshooting. The mechanical equipment (mixers, aerators and pumps) must be constantly maintained. As well, the influent and effluent must be severely compromised constantly monitored and the control parameters adjusted, if necessary, to avoid abnormalities that could kill the plant is under- or over- designedactive biomass and the development of detrimental organisms which could impair the process (e.g. An Activated Sludge process is appropriate for almost every climate, filamentous bacteria).

==Health Aspects/Acceptance=References===* Crites, R. and Tchobanoglous, G. (1998). Small and Decentralized Wastewater Management Systems. WCB/McGraw- Hill, New York, US. pp. 451-504. (Book; Comprehensive summary including solved problems)

Because of space requirements* Ludwig, H. F. and Mohit, K. (2000). Appropriate Technology for Municipal Sewerage/Excreta Management in Developing Countries, Centralized treatment facilities are generally located away from the densely populated areas that they serveThailand Case Study. The Environmentalist 20 (3): 215-219. Although (Assessment of the effluent produced is appropriateness of high quality, it still poses a health risk and should not be handled directly.activated sludge for Thailand)

The mechanical equipment (mixers*Tchobanoglous, G., Burton, aerators F. L. and pumpsStensel, H. D. (2004) must be maintained constantly. As wellWastewater Engineering: Treatment and Reuse, the influent and effluent must be monitored constantly to ensure that there are no abnormalities that could kill the active biomass and to ensure that detrimental organisms have not developed that could impair the process Metcalf & Eddy, 4th Ed. (eInternat.gEd. filamentous bacteria).McGraw-Hill, New York, US. (Detailed design information)

===Acknowledgements===