Microorganisms have usually been considered to be contaminants and troublesome. Microorganisms are common to surface waters but are usually absent in deep well waters. Deep well water that has been pumped into a tank often develops growths of microorganisms.
Many of these microorganisms grow, although at reduced rates, in cold water and even under ice. Many of them form coatings, thus greatly reducing water carrying capacities. Sometimes these coatings break loose in large masses.
Now, there are claims of treatment. There is no doubt that you will remove some manganese with a biological filter. The question will be how reproducible and reliable the results will be.
Also, if you allow the microorganisms to grow in potable water, you are also going to have to include a process that will remove, destroy, and prevent the microorganisms from traveling downstream.
Slow sand filters are a low-tech unit requiring no knowledge of water treatment and maybe suitable for small installations. The slow sand filter works by physical removal and partially by a biological mechanism. The filtration rate is so low through the slow sand filter makes it uneconomical for most applications.
