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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 }}|}

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:Activated_sludge.png |right|300px500px]]

[[Image:Icon_activated_sludge.png |right|95px]]<br>'''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.'''-<br>

Different configurations of the Activated Sludge process can be employed to ensure that the wastewater is mixed and aerated (with either air or pure oxygen) in an aeration tank. The microorganisms oxidize the organic carbon in the wastewater to produce new cells, carbon dioxide and water. Although aerobic bacteria are the most common organisms, aerobic, anaerobic, and/or nitrifying bacteria along with higher organisms can be present. The exact composition depends on the reactor design, 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 and the effluent moves on for further treatment or discharge. The sludge is then recycled back to the aeration tank, where the process is repeated[[Image:Icon_activated_sludge.png |right|80px]]

'''An activated sludge process refers to a multi-chamber reactor unit that makes use of highly concentrated microorganisms to degrade organics andremove nutrients from wastewater to produce a high-quality effluent. To achieve specific effluent goals for BOD, nitrogen maintain aerobic conditions and phosphorus, different adaptations and modifications have been made to keep the basic Activated Sludge design. Aerobic conditionsactivated sludge suspended, nutrienta continuous and well-specific organisms (especially for phosphorus), recycle design and carbon dosing, among others, have successfully allowed Activated Sludge processes to achieve high treatment efficienciestimed supply of oxygen is required.'''

{{procontable | pro=- Good resistance against shock loading. <br> - Can Different configurations of the activated sludge process can be operated at a range of organic employed to ensure that the wastewater is mixed and hydraulic loading ratesaerated in an aeration tank. High reduction of BOD Aeration and pathogens (up to 99%). <br> - Can mixing can be modified to meet specific discharge limitsprovided by pumping air or oxygen into the tank or by using surface aerators. | con=- Prone The microorganisms oxidize the organic carbon in the wastewater to complicated chemical produce new cells, carbon dioxide and microbiological problemswater. <br> - Effluent might require further treatment/ disinfection before discharge. <br> - Not all parts and materials may Although aerobic bacteria are the most common organisms, facultative bacteria along with higher organisms can be available locally. <br> - Requires expert design and supervision. <br> - High Capital cost; high operation cost. <br> - Constant source of electricity is requiredpresent. <br> - Effluent and sludge require secondary treatment and/or appropriate discharge.}}

===Design Considerations=== Activated Sludge is only appropriate for sludge processes are one part of a centralized complex treatment facility with system. They are usually used after primary treatment (that removes settleable solids) and are sometimes followed by a final polishing step (see POST, p.136). The biological processes that occur are effective at removing soluble, colloidal and particulate materials. The reactor can be designed for biological nitrification and denitrification, as wellas for biological phosphorus removal. The design must be based on an accurate estimation of the wastewater composition and volume. Treatment efficiency can be severely compromised if the plant is under-trained staffor over-dimensioned. Depending on the temperature, constant electricity and a highly developed centralized management system the solids retention time (SRT) in the reactor ranges from 3 to 5 days for BOD removal, to 3 to ensure that the facility is operated and maintained correctly18 days for nitrification.

Activated Sludge processes are one part of a complex The excess sludge requires treatment system. They are used following primary treatment (that removes settleable solids) to reduce its water and organic content and before to obtain a stabilized product suitable for end-use or final polishing disposal. It isimportant to consider this stepin the planning phase of the treatment plant. The biological processes that occur are effective at removing solubleTo achieve specific effluent goals for BOD, colloidal nitrogen and particulate organic materials for biological nitrification phosphorus, different adaptations and denitrification and for biological phosphorus removalmodifications have been made to the basic activated sludge design. This technology is effective for the treatment of large volumes of flows: 10Well known modifications include sequencing batch reactors (SBR),000 to 1oxidation ditches,000extended aeration,000 peoplemoving beds and membrane bioreactors.

Highly trained staff <br>{{procontable | pro=- Resistant to organic and hydraulic shock 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 for <br>- High capital and operating costs <br>- Requires operation and maintenance by skilled personnel <br>- Prone to complicated chemical and troublemicrobiological problems <br>-shooting. The Not all parts and materials may be locally available <br>- Requires expert design must be based on an accurate estimation of the wastewater composition and volume.construction <br>- Sludge and possibly effluent require further treatment and/or appropriate discharge}}

===Appropriateness=== An activated sludge process is only appropriate for a Centralized Treatment efficiency can be severely compromised if facility with a well-trained staff, constant electricity and a highly developed management system that ensures that the plant facility is correctly operated and maintained. Because of economies of scale and less fluctuating influent characteristics, this technology is under- or over- designedmore effective for the treatment of large volumes of flows. An Activated Sludge activated sludge process is appropriate for in almost every climate. However, treatment capacity is reduced in colder environments.

===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 of high quality, it still poses a health risk and should not be directly handled. In the excess sludge pathogens are substantially reduced, but not eliminated.

Because of space requirements===Operation & Maintenance=== Highly trained staff is required for maintenance and troubleshooting. The mechanical equipment (mixers, aerators and pumps) must be constantly maintained. As well, Centralized treatment facilities are generally located away from the densely populated areas influent and effluent must be constantly monitored and the control parameters adjusted, if necessary, to avoid abnormalities that they serve. Although could kill the active biomass and the effluent produced is development of high qualitydetrimental organisms which could impair the process (e.g., it still poses a health risk and should not be handled directlyfilamentous bacteria).

==Maintenance=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)

The mechanical equipment (mixers* Ludwig, aerators H. F. and pumpsMohit, K. (2000) must be maintained constantly. As wellAppropriate Technology for Municipal Sewerage/Excreta Management in Developing Countries, 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 Thailand Case Study. The Environmentalist 20 (e3): 215-219.g. filamentous bacteria(Assessment of the appropriateness of activated sludge for Thailand).

==Acknowledgements=={{* von Sperling, M. and de Lemos Chernicharo, C. A. (2005). [https:Acknowledgements Sanitation}}//www.iwapublishing.com/sites/default/files/ebooks/9781780402734.pdf Biological Wastewater Treatment in Warm Climate Regions, Volume Two]. IWA Publishing, London, UK.

==References *Tchobanoglous, G., Burton, F. L. and external links==Stensel, H. D. (2004). Wastewater Engineering: Treatment and Reuse, Metcalf & Eddy, 4th Ed. (Internat. Ed.). McGraw-Hill, New York, US. (Detailed design information)

* Crites, R. and Tchobanoglous, G. (1998). Small and Decentralized Wastewater Management Systems. WCB and McGraw-Hill, New York, USA. pp 451–504. (Comprehensive summary including solved problems.)===Acknowledgements=== * Ludwig, HF. and Mohit, K. (2000). Appropriate technology for municipal sewerage/Excreta management in developing countries, Thailand case study. The Environmentalist 20(3): 215–219. (Assessment of the appropriateness of Activated Sludge for Thailand.) * von Sperling, M. and de Lemos Chernicharo, CA. (2005). Biological Wastewater Treatment in Warm Climate Regions, Volume Two. IWA, London. * Tchobanoglous, G., Burton, FL. and Stensel, HD. (2003). Wastewater Engineering{{: Treatment and Reuse, 4th Edition. Metcalf & Eddy, New York.Acknowledgements Sanitation}}