Filtration is a process used to separate solids from liquids or gases using a filter medium that allows the fluid to pass through but not the solid. The term “filtration” applies whether the filter is mechanical, biological, or physical. The fluid that passes through the filter is called the filtrate. The filter medium may be a surface filter, which is a solid that traps solid particles, or a depth filter, which is a bed of material that traps the solid.
Filtration is typically an imperfect process. Some fluid remains on the feed side of the filter or embedded in the filter media and some small solid particulates find their way through the filter. As a chemistry and engineering technique, there is always some lost product, whether it’s the liquid or solid being collected.
In water treatment filtration systems are used as primary barrier to the suspended particles. However, in wastewater treatment the filtration system is a part of tertiary treatment process. Conventionally depth or gravity filtration were very popular. However, due to their limitation of slow speed and large size requirement the pressure sand filters are in trend. The filters can also be classified on the bases of the filter media in use. For example sand, carbon and special purpose resins.
Ewalts has developed purpose fit filtration system for water and wastewater treatment processes-