A layer of sand or gravel is used when sewage goes through sewage treatment. Before sewage comes to the bacteria bed, it should already have gone thru part of the sewage treatment. At the bacteria bed, sewage gets exposed to (or has contact with) air, while microorganisms make some change to that sewage. The oxygen in the water kills the microbes, which are anaerobic.
The name "bacteria bed" is sometimes used about this type of filter.
References[change | change source]
- "Definition of bacteria bed". The Free Dictionary. Retrieved 2007-07-26.
- "Slow Sand Filtration" (PDF). National Drinking Water Clearinghouse. Archived from the original (PDF) on 2019-07-13. Retrieved 2021-07-05.
- A. Rushton, A.S. Ward, R.G. Holdich 1996. Introduction to solid-liquid filtration and separation technology. Wiley VCH. ISBN 978-3-527-28613-3