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An Anaerobic Filter is a fixed-bed biological reactor. As wastewater flows through the filter, particles are trapped and organic matter is degraded by the biomass that is attached to the filter material. This technology consists of a sedimentation tank or septic tank (refer to Technology Information Sheet S9: Septic Tank) followed by one to three filter chambers. Filter material commonly used includes gravel, crushed rocks, cinder, or specially formed plastic pieces. By providing a large surface area for the bacterial mass, there is increased contact between the organic matter and the active biomass that effectively degrades it.
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