Research on Variables Affecting Filtration

Previous theoretical and experimental work has established the mathematical laws describing the water quality and head loss changes through the depth and during the time of operation of a filter run. The present study has evaluated how this performance will change in other filter runs operated with different sized media, or at different filtration rates, or at different water temperatures. Using a particulate suspension of plastic microspheres (diameter 1.3 microns) to conform with the mathematical idealizations, it has been found that filter efficiency varies inversely with grain size, inversely with the filtration rate, and as the inverse square of the water viscosity. Some examples of different filter operations are calculated and compared using these relationships. Other published theoretical and experimental studies have been reviewed, which also indicate inverse relationships between filter efficiency and grain size, rate, and viscosity. However, these are not all identical and it appears that each suspension may have characteristic exponents associated with the three variables investigated.