In a previous column, I mentioned that sewage treatment mounds are like a single-pass sand filter. That prompted follow-up questions about the use of media filters and how they relate to mounds. In general, media filters — either single-pass or recirculating — are used for advanced pretreatment of septic tank effluent before final treatment and dispersal. Usually, additional pretreatment is used in areas where there are environmental or health concerns and conventional septic tank to trenches, mounds or at-grades do not provide the desired level of treatment.
Media filters consist of a lined or watertight structure containing media of predetermined specifications.
