Natural water purification
A natural system that rids of minerals, metals, organic substances, bacteria, and suspended particles; made up of the hydrologic cycle, bacterial action, and filtration; in a perfect world, could be used to create purified or pure water, but acidic water
Evaporation
The first part of the hydrologic (and natural water purification) cycle, where the Sun heats the water, so that it turns into vapor, leaving behind dissolved substances (heavy metals, minerals, molecular substances)
Condensation/ precipitation
The second part of the hydrologic cycle (and natural water purification process), where water vapor- that is, if not affected by modern airborne pollution- creates tiny droplets of liquid/ The last part of the hydrologic cycle, where water droplets fall t
Hydrologic cycle
The first part of the natural water purification process, that consists of evaporation, condensation, and precipitation; moves in a constant loop as water goes from the ground to the air and back again
Bacterial action
The next part of the natural water purification process, after condensation, where bacteria under the soil convert suspended/ dissolved substances in the water into carbon dioxide/ water/ compounds; these bacteria help purify the water
Filtration
The last step of the natural water purification process, after bacterial action, where water seeps deeper into the ground, passing through gravel, sand, and rock, which gets rid of waterborne bacteria and suspended matter
Water treatment (pre- use purification)
When water is cleaned by a municipal water treatment plant after it has already been through the natural water purification process, and before it is used in homes and buildings; human- made water purification process
Screening
The first step of water treatment, where water from some source (lake, river, etc.) goes through a metal screen to keep out fish, sticks, containers, and other large objects
Pre- chlorination
The second step of water treatment, where chlorine is added to the water ro rid of disease- causing microorganisms
Flocculation
The third step of water treatment, where crystals of alum (aluminum sulfate)- Al?(SO?)?and slaked lime (calcium hydroxide)- Ca(OH)?are added to the water, where they react and form aluminum hydroxide- Al(OH)?, a sticky, gelatinous material that traps susp
Settling/ sand filtration
The fourth step of water treatment, where the aluminum hydroxide with trapped suspended particles from flocculation is allowed to settle at the bottom of a container, while the water moves on to be filtrated through sand (fifth step) to clear any remainin
Post- chlorination
The sixth step of water treatment, where the chlorine levels of the water are adjusted to make sure there's a low but adequete amount
Aeration
An optional seventh step of water treatment where water may be sprayed or mixed into the air to remove odors and improve its taste
pH adjustment
An optional eight step of water treatment where the pH levels of the water are adjusted by adding lime (clacium oxide)- (CaO), to make it more neutral, ensuring that its acidity does not dissolve pipe metal and cause it to pick up impurities
Flouridation
An optional ninth step of water treatment where approximately 1 ppm of flouride is added to water, to prevent tooth decay
Chlorination
Adding chlorine to water (in municipal water treatment plants), to kill any diease- making microorganisms; 3 ways chlorine is added are to
-Bubble in chlorine gas- Cl?, which is not very soluble in water but creates a compound
-Sodium hypochlorite- NaOCl-
Chlorination cons
Chlorine, under some conditions, can react with organic compounds in water created by decomposing organisms, to form substances that can be harmful to humans in large concentrations; includes THMs; because of this health risk, the EPA concentration in tre
THM (trihalomethanes)
A group of substances that can be created when chlorine reacts with organic compounds in water; a common type is chloroform- CHCl?, which can cause cancer
Carcinogen
A substance known to cause cancer, such as THMs like chloroform
Alternative 1- Add a charcoal filter
Pros: Can remove most organic compounds from water; cons: Expensive to install and use, disposal is a hassle, and must be replaced often
Alternative 2- Instead of chlorination, use ozone (O?) or ultraviolet light
Pros: Can disinfect water like chloine can; cons: Can't protect water from bacteria when it leaves the plant, and ozone can be toxic if handled/ used incorrectly
Alternative 3- Eliminate pre- chlorination
Pros: Chlorine can still be added later in post- chlorination; cons: Less chlorine concentration can lead to a build- up of bacteria, and THMs may still be able to form
Hard water
Water that has an excess of dissolved calcium (Ca?�), magnesium (Mg?�), or iron (III) (Fe?�) ions in it; it is usually formed in groundwater, which can pass over limestone, chalk, and other substances that have the three mentioned ions; when hydrogen carb
Hard water problems
Though hard water is not a health concern, it is a financial concern, because it can react with soap to form a flaky ir scummy precipitate (unlike regular water, which lathers up) that stains clothes, skin, and hair; though boiling hard water can remove t
Soft water
Water that is not hard; water can be softened by ion exchange, boiling it (though this forms a solid scale), adding sodium carbonate- washing soda- (Na?CO?), borax, trisodium phosphate, and hexametaphosphate, like Colgan (which makes the hard water ions i
Detergent
Substances in cleaning products that, unlike soap, do not form precipitate in hard water; many early ones were not biodegradable by bacteria, so when dumped they formed huge mounds of suds, and also had phosphate ions (PO??�) that sped up algae growth; to
Ion exchange
A process to soften water that involves passing hard water through a certain resin, found in home water softeners; first, the resin is filled with sodium cations (Na?�), then hard water flows in, and its calcium and magnesium are attracted to the resin be
Water softener
A tank consisting of an ion exchange resin, that contains millions of miniscule, insoluble beads that attract cations; when the resin is filled with hard water ions, it must be renewed, so concentrated salt water is added, which replaces the hard water io
Reverse osmosis
A process where concentrated water is forced by pressure through a semipermeable membrane to create purified water
Colligative property
A property that depends on the concentration of salt solution, like osmotic pressure
Permeate
The purified water created from reverse osmosis, when it seperates from salts and dissolved solids