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Status: Finished  |  Genre: Non-Fiction  |  House: Booksie Classic

Submitted: September 12, 2014

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Submitted: September 12, 2014



Filtration- The process of separating suspended particles from the fluid through a porous material in which the fluid can pass while the suspended particles are retained.

Evaporation-process of becoming a vapor 

Filtration is used to separate a solid from a liquid. In a kitchen one uses a strainer to separate particles but in a lab filter paper is used. Powders cannot be dissolved as they have big particles. For this process a filter funnel, conical flask ,retort stand ,filter paper is used one can even use fritter glass or any porous material.  The solid particles are left as residue and the liquid is the filtrate after the process. The solid is separated from the liquid phase by passing the mixture over a filtering media. Filtering media is characterized by being chemically inert to the mixture, and having small pathways for the liquid to pass through, but these pathways should be smaller than the soiid particle size.

Eg. A mixture of sand and water can be separated by filtering. 

This is because the water can pass through the tiny holes in the filter paper, but the sand particles are too   Large to pass through and get stuck in

A mixture of salt and water can't  be separated by filtering.  

This is because the salt has dissolved in the water and will Pass through   the filter paper with the water.

 When you mix salt and water together, the salt Has dissolved.

  If you  heat   a solution of salt and water the water will   Evaporate.

The tiny particles of Salt don't evaporate - they stay behind. 

When all the water has   Evaporated all that remains in the container is   Salt

take the mixture of water and chalk powder. Take a filter paper and fix it in a funnel. Then, pour the mixture slowly into a container; through the funnel. You will be able to see the particles of chalk powder on the filter paper left as residue and the liquid as filtrate.
This method is used to separate an insoluble solid from water. Although when a solid has dissolved than we use evaporation. a tripod stand, Bunsen burner, evaporating dish, wire gauze is required. If we need to collect the water a beaker, watch glass is added instead if the evaporating dish.
When the water will touch the cold surface if the glass it will condense. It is important to minimize evaporation during filtration because some of the compounds can disappear in the air by evaporation. To avoid recrystallization in the funnel. And rapid crystallization will occur with maximum evaporation.

To separate bacteria
A self-cleaning water filtration system includes a pre-filter to filter oils and relatively medium sized particles in a water flow, a multi-stage filter to purify and provide a second level of filtration to the water flow, and a self-cleaning filter to provide a third level of filtration to the water flow. Water flow through the filter media of the self-cleaning filter is redirected to flush waste to a containment-tank filter. The self-cleaning filter has a purge output, which may spray the pre-filter to substantially remove particles from the pre-filter for collection in the containment tank. The multi-stage filter may have at least two layers of filter media. The pre-filter may be disposable and comprised of a mineral sanitizer positioned between two layers of an oil absorbing fabric.
Water filtration has many different applications - commercial, industrial and personal. Different types of water filtration methods serve different purposes. 



Vacuum filtration is used primarily to collect a desired solid, for instance, the collection of crystals in a recrystallization procedure. Vacuum filtration uses either a Buchner or a Hirsch funnel. Vacuum filtration is faster than gravity filtration, because the solvent or solution and air is forced through the filter paper by the application of reduced pressure. The reduced pressure requires that they be carried out in special equipment:

Büchner or Hirsch funnel
heavy-walled, side arm filtering flask
rubber adaptor or stopper to seal the funnel to the flask when under 
vacuum source

the conditions where gravity filtration is recommended are NOT present
a quick separation is required

Sediment filters are typically used as a pre-treatment method to help remove debris and particles from water. This will avoid any clogging that might compromise the effectiveness of other, more effective filtration methods, such as carbon adsorption, down the line. These range from simple replacement pleated filters, to filters with self-cleaning backwash capabilities.


Carbon Adsorption
Activated carbon filters have a porous surface which traps microscopic particles and large organic molecules. The activated surface areas cling to (adsorb) smaller organic molecules. There are two basic types of activated carbon filters: granular and solid block. Granular activated carbon is most commonly used in household drinking water filtration products. These are easy to install and inexpensive. They significantly reduce bad taste and odor caused by gases and chemicals like chlorine and its byproducts, while leaving behind natural minerals that are essential to good health.. Depending on micron size, they may also remove some microorganisms. Solid block carbon filters have a solid honeycombed structure. These are usually whole-house filters, installed directly into the house water supply. They are more expensive than granular activated carbon filters but require less frequent installation, and they reduce more chemicals including pesticides.

Ceramic filters
The most common types of ceramic water filters are pot, cartridge and candle, both of which are typically undersink or countertop. These filters may be treated with silver - a powerful antibiotic - for the reduction of bacteria and many other microorganisms. They may also contain carbon for the reduction of chlorine and other chemicals. The cost of a ceramic filter is low; this, combined with its long filter life and its ability to remove a long list of contaminants makes it advantageous. However, these filters have a much lower flow rate than carbon filters. The simplest form of ceramic filters - the clay pot - has been manufactured for use in developing countries where access to clean water is very limited.


Probably the oldest method of water purification, a distiller boils water until it vaporizes. The vapor is carried into a condensation chamber where it cools and liquifies again. Impurities are left behind in the boiling water chamber. There are several major disadvantages to this method of filtration. First, chemicals like chlorine and pesticides which have a boiling point lower than that of water are often carried over with the vapor and can become concentrated in the final product. Second, the process is costly in terms of energy and the amount of water used. Third, the purified water is usually very acidic and absent of natural minerals giving it a flat taste and taking away many of the healthy essentials found in mineral water. Therefore, distillation is not the best method of purification for municipally treated drinking water. 

UV Filtration

In UV filtration, ultraviolet radiation is used to inactivate microorganisms, thereby sanitizing water. However, this method will not remove particles or chemicals and must often be combined with other methods of filtration.


A membrane or, a semipermeable membrane, is a thin layer of material capable of separating substances when a driving force is applied across the membrane.
Once considered a viable technology only for desalination, membrane processes are increas- ingly employed for removal of bacteria and other microorganisms, particulate material, and natural organic material, which can impart color, tastes, and odors to the water and react with disinfectants to form disinfection byproducts (DBP). As advancements are made in membrane production and module design, capital and operating costs continue to decline.
The pressure-driven membrane processes discussed in this fact sheet are microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO).

Reverse Osmosis Filters

Osmosis is the diffusion of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentraion. Reverse osmosis, as the name implies, is the reverse of this process. Water is forced from an area of higher concentration across a membrane which traps most unwanted water contaminants. This method of purification is highly effective, significantly reducing most particles, chemicals and microorganisms, but it uses a lot of water, and RO  filter systems are more expensive than other types. They may be installed under a kitchen sink or fitted to a home's main water pipe.Ion Exchange Filters

Ion filtration
In the ion-exchange process, water travels across a bead-like spherical resin material containing ions which are exchanged with the ions in the water. The ion exchange method is typically used as a pre-treatment method to soften or deionize water. Because it does not remove particles or microorganisms, it should be followed by another method of filtration like carbon adsorption or reverse osmosis.


Gravity filtration

The mixture can be forced through the filter by either gravity or reduced pressure on one side of the filter (by creating a vacuum). It is possible to separate a solid from a liquid by either technique, however there are advantages to each technique.

Gravity Filtration is recommended when:

the mixture is hot (above room temperature)
the liquid is saturated with one or more reagents
the solvent is very volatile (chloroform, alcohols, ethers).

The importance of filtration is for salt separation as their is only 1% easy accessible fresh water. We can separate salt and impurities from water to drink. These methods are usually done in factories or labs

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