Process Water Treatment – Challenges and Solutions

Filtration Filtration removes suspended solids by mechanical means using a porous medium that allows passage of water while retaining solids. In general, the filters used for water treatment consist of either (a) bed filters, namely, the containers are partially filled with a porous layer of inert particles, or (b) made of cartridges or bags, usually made of synthetic porous material, and as a rule, they are designed to handle small as compared to the flowrates of the filter bed. Some bed filters or cartridge filters are classified as adsorption filters as described below. Precoat filter (see below) is also used to water pretreatment. Unit of measure used in connection with filtration to remove contaminants is micrometer microns, which is equivalent to one millionth of a meter (the smallest particle, which can be seen with the naked eye measuring 40 microns). Bed filters. In the filter layer, the water pressure itself provides the force needed to pass through the filter medium or media. Many types of inert materials can be the same size as the media. Filter layer shown in Figure 1 uses three coal, sand and garnet. The water flow may be either upwards or downwards. Typical bed filters can remove suspended solids to about 10 microns. An advantage of the filter bed is that they can be loosened to remove entrained solids, and therefore, these filters have a very long duration of life. It is obvious that they must be taken off-line during backwashing.