Practitioner's Tool / Primary Treatment Methods

Primary Treatment	Appropriate Use	Relative Cost	Operations and Maintenance	Effectiveness
Septic Tanks	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
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
Anaerobic Baffled Reactors	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
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