Carl Edison 2016-11-21 17:00:00
In the most basic form of filtration, a suspension is passed through filter paper that is supported in a glass funnel. The paper captures the solid particles and leaves the clear solution, called the filtrate, to make its way through the funnel and into a receiving container.
There are two main reasons to filter something: either to capture the solids that are suspended in the fluid, or to clarify the fluid in which the solids are suspended. One example of the first option would be to pan for gold. The water is passed through a sieve and the rocks that are left behind will hopefully contain gold. An example of the latter option would be in a swage treatment facility where the liquid is the wastewater and the solids are feces and other solid wastes.
Filtration can be further classified into liquid or gaseous, depending on which of the fluids makes up the filtrate. Another way to break down filtration is via the force that pushes the fluid through the filter: pressure, a vacuum, or gravity. The type of filter used can also distinguish the types of filtration. If you want to learn more about the different types of industrial filters, you may be interested in the Fil-Trek website for additional information.
One example of gas filtration in a practical application would be the household vacuum cleaner. A stream of dust-filled air is passed through a filtering bag inside the appliance. The bag traps solid pieces and allows clean air to return back out to the room. This is the same idea as with HVAC systems, which, in addition to heating and cooling, also remove pollen, dust, and other impurities from the air.
Different industries use gas filtration to filter the air in the workplace. For example, the gases from power plants that burn oil and coal are purified by passing them through filtering systems that collect those particles.
In liquid filtration, a liquid can be pulled through a filter using gravitational force, or via pressure, or a pressure differential created by a vacuum. Typically, in water purification, water runs down through filtering material like charcoal, sand, or gravel, al of which remove impurities. These layers can be several feet thick. If you want to learn more about liquid filtration, you may like to visit Lenntech for additional resources and information.
In small volumes of solution, a positive-pressure system can be used, wherein fluid is forced through a series of vertical plates covered with cloths that collect the solids. Alternatively, a vacuum filter can be used to allow atmospheric pressure to push the liquid through the vilter. Once the liquid is free from impurities, it can be passed through a different filter for clarification. This type of filter is commonly made of diatomaceous earth, which is a super-fine material made from the decay of marine organisms.
Sewage treatment is actually a complex process where waste water has harmful content removed from it so that it is made safe, thus being able to be returned to the environment. People in cities create enormous amounts of waste that contain viruses, bacteria, and other dangerous microorganisms. The devastating plagues that wiped out famous cities like Rome, Constantinople, and Rome were all a result of improper waste management in medieval and ancient times.
In municipal waste treatment centres, the larger particles are separated first, then the smaller particles. The sewage is chemically treated along the way. Through continual filtration, the water is eventually clarified of biosolids. The water is then further clarified using a deep-bed filter, and more air may be introduced using algae to further the aerobic decay.