Primary Treatment
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Appropriate Use
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Relative Cost
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Operations and Maintenance
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Effectiveness
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Septic Tanks
Septic Tank
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Residential or commercial sources with a population loading of less than 25 people
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Low - Can be constructed using local materials and labor
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Needs to be de-sludged every 3 to 5 years
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Moderate - Can reduce 40% to 60% of pollution loading
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Sewage Lagoons
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Small community or institutional sources, such as hospitals. Must be located well away from residential communities due to potential for odors and nuisances
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Low for areas where available land is plentiful and low value
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Low - Systems still require routine operation and maintenance tasks such as monitoring, weed and trash removal, scum and biosolids management
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Can be very effective as primary treatment devices. May also be designed for secondary treatment
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Anaerobic Baffled Reactors
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Residential or commercial facilities with a population loading of between 25 and 200 people
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Low - May be constructed with local materials and labor
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Low - Periodic desludging is required
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Good - Generally better performance than septic tanks. Can remove 75% of the pollution load
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Biogas Systems
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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
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Moderate - Some systems require tight specifications on construction
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Moderate - Take care to ensure the source wastewater is free of chemicals or disinfectants which can kill microbes that produce biogas
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Ineffective for human waste only. When waste includes animal manure, may produce enough biogas to meet cooking fuel demands
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