The British pint is about 20% larger than the American pint since the two systems are not compatible. Almost all other countries have standardized on the metric system, so the size of what may be called a pint varies depending on local custom.
It is usually measured by the depth (in mm) of the water layer that can enter the soil in one hour. An infiltration rate of 15 mm/hour means that a water layer of 15 mm on the soil surface, will take one hour to infiltrate. In dry soil, water infiltrates rapidly.
For the purpose of selecting the biofilter blower, the backpressure expected across the biofilter at this airflow rate is usually in the range of 20 to 120 mm H2O/m depth (0.22 to 0.9 inches H2O/ft), although the pressure drop can be considerably higher through dense composts and soil.here are several options for odor treatment, including chemical stripping, thermal destruction, and biofiltration. In many cases biofiltration is both the least expensive and most effective treatment option, which has led to its widespread use in the composting industry today.