Unit Two: Mixtures and Solutions

Purifying WaterSeparating Mixtures in our Homes

Separating Mixtures in Engines

Water Purification

• 90 percent of the world’s water is contaminated.

• There are a variety of microscopic organisms that can contaminate water supplies and cause potentially serious, even fatal, illnesses among wilderness travelers.

• The major danger in the backcountry from these infections is fluid loss due to diarrhea and vomiting, which can lead to hypovolemic shock and possibly death.

Biologically Contaminated and Toxic Water

• Biologically contaminated water:– contains microorganisms such as Giardia, bacteria, or

viruses that can lead to infections

• Toxic water:– contain chemical contamination from pesticide

runoffs, mine tailings, and so on.

• Boiling, filtering, or chemically treating water can remove or kill microorganisms, but it will not remove chemical toxins.

Boiling

• Boiling is the most certain way of killing all microorganisms.

– water temperatures above 160° F (70° C) kill all pathogens within 30 minutes and above 185° F (85° C) within a few minutes.

– To be extra safe, let the water boil rapidly for one minute, especially at higher altitudes since water boils at a lower temperature

Chemical Purification

• two types of chemical treatment:

– those using iodine– those using chlorine

– Remember that chemical purification methods may only be partially effective, depending on the water temperature.

Filtration

• There are a number of devices on the market that filter out microorganisms.

• A water filter pumps water through a microscopic filter that is rated for a certain-size organism.

• Depending on the micron rating of the filter, smaller organisms (like viruses) can pass through.

• Be cautious when selecting a filter.

Types of Filters• There are two basic types of filters

• Membrane Filters use thin sheets with precisely sized pores that prevent objects larger than the pore size from passing through.

– Pro: Relatively easy to clean. – Con: Clog more quickly than depth filters.

• Depth Filters use thick porous materials such as carbon or ceramic to trap particles as water flows through the material.

– Pro: Can be partially cleaned by backwashing. Activated carbon filters also remove a range of organic chemicals and heavy metals.

– Con: Rough treatment can crack the filter, rendering it useless.

Common Practices for Using a Water Filter

• Filter the cleanest water you can find. Dirty water or water with large suspended particles will clog your filter more quickly.

• Pre-filter the water either through a pre-filter on the pump or strain it through a bandanna.

• If you must filter dirty water, let it stand overnight for particles to settle out.

• According to the Red Cross, to purify drinking water use any of the following methods:

• 1)  Boil for five to ten minutes;

• 2)  Add ten drops of household bleach solution per gallon of water, mix well and let standfor thirty minutes.  A slight smell or taste of chlorine indicates water is good to drink.

• 3)  Add household tincture of iodine in the same manner as bleach above.

• 4)  Use commercial purification tablets, following package directions.  Two commercialbrand names as Halazone and Globaline.

Separating Mixtures at Home

Water Filters

• Reduces bad taste and odor, calcium, magnesium, copper and zinc.

• Highly effective in reducing sodium, pesticides and herbicides.

• Softens the water.

Flour Sifter

Colanders

Cheese-Cloth

• When the time comes to press your cheese you will first line the mold with a 18" square piece of sterile  cheesecloth.

• Prepare the cloth by placing it into boiling water for 30 seconds.

• Remove the cloth with a tongs or spoon and rinse it with cold water.

• It should then be wrung out and snapped dry.

• The cloth lining will prevent the curd from being squeezed through the mold.

What is Hard Water?

• Hard water contains large amounts of calcium and magnesium – two minerals that cause the soapy scum on glasses and lime residue on bathroom fixtures.

• While suitable for drinking and gardening, hard water can cause mineral build-up in water heaters, pipes, dishwashers and showerheads, reducing its flow.

• Soap and shampoo’s ability to lather is reduced, and laundry becomes stiffer and duller in appearance.

• A water softener uses a medium that serves to exchange "ions" of calcium and magnesium with sodium and potassium.

• A water softener reduces water hardness, making it easier to shower and clean fabrics and dishes. With softened water, less soap is needed for bathing and laundry. Skin feels cleaner and clothing softer.

• Pipes, fixtures and appliances have less scale build-up. With less build-up, appliances can operate efficiently. Mineral-derived odours may be reduced; and, there are fewer deposit stains on bathroom fixtures.

Other Filters

• Oil, gas, and air filters in various engines help to keep impurities out of the mixtures required to run engines.

Oil Filters

Gas Filters

Air Filters