The precision you need to purify water depends on what you go to use it. More commonly, however, the raw water needs to be purified for drinking, which means removing the particulate matter, heavy metals, and organic contaminants such as bacteria and viruses. You can climb more purification methods up or down for various quantities of water.
Mechanical methods physically screened filter bacteria and other contaminants from water. Highest mechanical filtration method is reverse osmosis, but this filter produces large amounts of wastewater. Other mechanical filters use porous sheets to sift particles and bacteria. Another method is to use a deep layer of sand. The water passes through and larger contaminants are trapped in the sand. This does not eliminate biological contamination.
To improve the sand filters and help remove heavy metals and biological contaminants, you can add carbon or activated carbon mechanical filter. For example, a sand filter, activated carbon layer below the sand helps produce benefits in both materials. Granular activated carbon (GAC) is a common component of filtration systems for water purification at home.
Add some chemicals eliminates biological agents in water, but does not eliminate heavy metals and toxins. A chemical additive family is chlorine. You can use chlorine bleach to purify contaminated water, both small and large quantities. Add 1/2 tsp. of bleach in 5 gallons (18.92 liters) of raw water to make it safe to drink. You can scale from this measure to large amounts of water. A gallon (3.78 liters) of bleach treats about 3,800 gallons (14,384 liters) of raw water.
Iodine is another chemical that disinfects the water. However, this method should not be used if you are pregnant, you have an allergy to iodine or thyroid disease. Iodine no pills used by hikers and campers, but another method is the use of iodine. The dyes are available in grocery stores as 2% iodine in alcohol and water. Five drops of iodine disinfect one liter of water in about 15 minutes. Increasing 1 tsp. tincture of iodine is at about 90 liters of water.
Ultraviolet light kills living things in the water, including viruses. Not because it removes particles, it is a good idea to use mechanical filtration first. There ultraviolet filters available for use in home aquariums. A water pump moves the water through the filter, which uses an ultraviolet light shining into a tube to kill organisms. The velocity of the water through the filter depends on the brand of filter you are using and in the instructions of the manufacturer.
Whatman Capsule Filter
The filtration of large sample volumes requires products which permit high throughput and flow rates. Whatman capsule filters combine high efficiency media and innovative design features with a choice of filtration media for use in a wide range of applications. A range of capsule sizes is available enabling users to scale-up volumes from a few liters to several hundred liters, whilst using the same filter media type.
These capsules are available with a variety of end fittings for easy connection in a range of process lines. Whatman capsule filters are recommended for the fast and efficient filtration of many different sample types. The product selection guide on page 13 readily identifies the most appropriate product based on particle retention. The table on pages 14 and 15 indicates the end fittings available for each product range. Whatman products are manufactured with the highest quality materials, under exacting clean room conditions using ISO-controlled manufacturing processes. All devices are produced without the use of adhesives to ensure product purity.
Polycap AS 36 filter by Whatman is recommended for filtering aqueous solutions. It combines a glass microfiber prefilter and a nylon membrane, prolonging the life of the filter. Allows for large volumes with difficult samples to be filtered easily. 36mm Capsule: 400cm2 (62 in2). Nylon membrane layer is inherently hydrophilic, has low extractables, is bio-safe and has excellent flow rates. Ultra-clean containing no surfactant or mold release agents.
Housing thermally fused (no glues, adhesives or extraneous materials). Integrity-testable by bubble point, pressure decay or forward flow methods. Provides highly effective filtration area in a small size. Autoclavable some pre-sterilized with gamma irradiation. Manufactured in clean room facilities under ISO quality systems. Sterile.
Applications Include: admixtures, biologicals, buffers, cleaning/rinsing solutions, enzymes, extemporaneous solutions, immunologicals, irrigation solutions, ophthamalic solutions, pharmaceutical solutions, reagent preparation, salt solutions, therapy solutions, tissue culture media, nutrients, and viral suspensions.