Practitioner's Tool / Primary Treatment Methods

< Practitioner's Tool
Primary Treatment Appropriate Use Relative Cost Operations and Maintenance Effectiveness
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Septic Tanks
Septic Tank

Residential or commercial sources with a population loading of less than 25 people
Low - Can be constructed using local materials and labor
Needs to be de-sludged every 3 to 5 years
Moderate - Can reduce 40% to 60% of pollution loading
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Sewage Lagoons

Small community or institutional sources, such as hospitals. Must be located well away from residential communities due to potential for odors and nuisances
Low for areas where available land is plentiful and low value
Low - Systems still require routine operation and maintenance tasks such as monitoring, weed and trash removal, scum and biosolids management
Can be very effective as primary treatment devices. May also be designed for secondary treatment
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Anaerobic Baffled
Reactor (ABR) 1

Anaerobic Baffled
Reactor (ABR) 2

Residential or commercial facilities with a population loading of between 25 and 200 people
Low - May be constructed with local materials and labor
Low - Periodic desludging is required
Good - Generally better performance than septic tanks.  Can remove 75% of the pollution load
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Biogas Systems

For animal manure or other high strength waste.  Can be used for small community systems that combine waste from fish and animal operations, people and commercial activities
Moderate - Some systems require tight specifications on construction
Moderate - Take care to ensure the source wastewater is free of chemicals or disinfectants which can kill microbes that produce biogas
Ineffective for human waste only.  When waste includes animal manure, may produce enough biogas to meet cooking fuel demands