Re: Water and Chlorine
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Biologically Active Sand Filter
http://www.friendswhocare.ca/I%20-%2...e%20Manual.doc
Installation, Operation, and Maintenance Manual
BioSand Water Filter
Humanitarian Service
Last Revised: March 2005
INSTALLATION
For a BioSand filter to operate properly, it must be installed and commissioned correctly. Make a checklist and use it to ensure that you have everything you’ll need before you head out to install a filter. A filter maintenance guide (such as a laminated sheet) should be left with the users of each filter. This guide could be attached to the filter or placed on a wall adjacent to the filter.
TRANSPORTING THE FILTER
Always consider the safety issues related to moving the filter. There can be injuries due to strains of the back, arms, and knees. Watch out for crushing or pinching of fingers and toes under or behind the filter. Keep in mind the size of the filter (12” x 12” x 36”) and its weight (160 Lbs - plus an additional 100 Lbs of media). It can be difficult and awkward to move this large object.
Some ways to move the filter include:
• Cart – animal or human powered
• Car, truck, or boat
• Carrying slings – wide, heavy canvas straps placed over the shoulder to lift a heavy object
• Dolly – a frame or rack with small wheels, strong enough to carry the weight
• Rollers – metal or wooden, round pieces that can be used to move the filter short distances
POSITIONING THE FILTER
It is important to determine a good location for the filter. Locating the filter inside the home is important not only for filter effectiveness, but also for the convenience of the user. If the users can access the filter easily, they will be more likely to use and maintain it. Once filled with media, the filter should not be moved.
The filter should be placed:
• In a protected location away from sunlight, wind, rain, animals, and children
• Preferably inside the home
• Near the food preparation or kitchen area (depending on the space and layout of the house)
• Where it can and will be used and maintained easily
• On level ground
• So that water can easily be poured in the top
Tip: You may have to add a step if the users are short, so that they don’t have to lift the bucket of unfiltered water above shoulder height.
• Where there’s adequate room for hauling and pouring pails of water into the filter, and storing the filtered water
PLACE THE MEDIA
Estimated Time: 10 minutes
Tools Needed:
• Approximately 3 litres of washed _” gravel
• Approximately 3 _ litres of washed _” gravel
• Approximately 25 litres of washed sand
• A stick (approximately 40” long, 1” x 2” is preferred)
• Measuring tape
• At least 2 buckets of water
1. Ensure that the drain hole (the standpipe opening at the bottom inside of the filter) is clear and unobstructed (i.e. is not covered by concrete and is not plugged by any debris.) The flow rate through the copper pipe without any media in the filter should be 1 litre / 25 seconds.
Tip: This step should have been done when the filter was removed from the mold, however, double check now before you get too far into the installation.
2. Ensure that the inside of the filter has been cleaned out (including dirt, dust, and oil from the mold).
3. Place a stick inside the filter so that it’s touching the bottom of the filter.
4. Draw a horizontal line on the stick where it meets the top edge of the filter.
5. Measure and mark a line 2” down from the first line.
6. Fill the filter half full of water.
Note: The media must always be added with water already in the filter to prevent pockets of air from being trapped within the media.
7. Add approximately 2” of underdrain (_”) gravel to the filter.
8. Level out the gravel, and use the stick to measure how much has been added. Place the bottom of the stick on the gravel. When the 2nd line on the stick lines up with the top edge of the filter, you have added enough gravel.
Note: Ensure that the gravel covers the drain hole near the bottom of the filter.
9. Measure and mark a line 2” down from the second line.
10. Add approximately 2” of support layer (_”) gravel to the filter.
11. Level out the gravel, and use the stick to measure how much has been added. Again, place the bottom of the stick on the gravel. When the 3rd line on the stick lines up with the top edge of the filter, you have added enough gravel.
12. Quickly pour approximately 20 litres of washed sand to the filter (ensuring that there is always water above the surface of the sand).
Note: A random distribution of different sand grain sizes is critical to the proper operation of the filter. Adding the sand quickly maintains the random distribution by not allowing the different sizes of grains to settle into layers.
13. Continue adding smaller quantities of sand until water starts to pour out of the spout. (Again, make sure that there is always water above the surface of the sand. Add water if necessary.)
14. When the water stops pouring out of the spout, the water level is equalized.
Note: The water level in the filter is determined by the spout. Due to a siphoning effect, the water will stop coming out of the filter when the water is at the same level as the bottom of the spout.
15. Smooth out the sand and then measure the depth of the water above the sand bed.
16. If the water depth is less than 2”: remove sand until the depth is 2” (with the sand surface level and the water level equalized).
17. If the water depth is more than 2”: repeat steps 13 to 17 until the water depth is 2”.
18. Smooth out the surface of the sand so that it’s as level as possible.
FLUSH THE FILTER
Estimated Time: 1 hour
Tools Needed:
• Diffuser
• 40 – 80 litres of water
1. Place the diffuser plate on the ledge inside the filter. Ensure that it fits snugly.
Note: The diffuser must not be touching the surface of the water at its resting level. That would greatly reduce the amount of oxygen in the standing water layer, affecting the survival of the schmutzdecke.
2. Place a receiving container under the spout. The water that it captures can be reused.
3. Pour the cleanest available water into the filter (turbidity < 30 NTU).
4. Observe the water coming out of the spout.
5. Continue adding water to the filter until the water coming out of the spout is clear. This may take 40-80 litres (10-20 Gallons)
Note: If the outlet water doesn’t run clear after 100 litres (25 Gallons), the gravel or sand was too dirty to start with. It is probably easiest to take the media out, wash it in pails, and then place it back in the filter.
TEST FLOW RATE
Estimated Time: 5 minutes
Tools Needed:
• Measuring container with 1 litre mark
• Stopwatch
• Bucket
1. Fill the filter to the top with water.
2. Place your measuring container under the spout to collect the outlet water.
3. Measure the time it takes to fill the container to the 1 litre mark. It should take between 50 – 80 seconds.
4. If it takes longer than 80 seconds, the flow rate is too slow.
• The filter will still work, but it may clog faster and more often, requiring more maintenance
• If it takes too long to get a pail of water, the user may not like the filter and may use untreated water
• The flow rate can be improved by “swirling” the top layer of the sand and then scooping out the dirty water
• If a few “swirl & dumps” do not improve the flow rate substantially, the sand is either too fine or too dirty – you will have to rewash the sand
5. If it takes less than 50 seconds to fill the measuring container to 1 litre, the flow rate is too fast.
• The filter may not function effectively
• The media should be replaced with finer media (less washed)
• A less preferable option is to run a considerable amount of water through the filter until the flow rate decreases (due to the capture of finer particles and faster growth of the biolayer)
Note: The flow rate through the filter decreases as the height of the water in the influent reservoir drops. As the water level reaches the diffuser, treated water may only drip out of the filter spout. It can take 40 – 90 minutes for the 20 litres in the reservoir to completely pass through the filter.
DISINFECT THE SPOUT
Estimated Time: 10 minutes
Tools Needed:
• 3’ of garden hose that just fits over the filter spout
• 1 hose clamp (if available)
• Funnel (can be made from the top of a soda or water bottle)
• Bleach solution (1/2 teaspoon bleach to 2 litres of water)
Note: Do NOT pour chlorine bleach into the top of the filter!
1. Place the garden hose over the filter spout.
2. Clamp the hose in place with the hose clamp.
3. Place the funnel on the other end of the garden hose.
4. Hold the funnel higher than the top of the filter, and pour 2 litres of bleach solution into the funnel.
5. Hold in place for 2 minutes.
6. Remove the garden hose and drain the bleach solution
7. Wipe the outside of the spout with a clean, bleach-soaked cloth.
8. Add 20 litres of water to the top of the filter to flush the bleach out. Instruct the user not to use this water for drinking or cooking.
9. Place the lid on the filter.
OPERATION
ESTABLISHING THE BIOLAYER
• The schmutzdecke or biolayer is the key bacteria removing component of the filter
• Without it, the filter removes some contamination through screening of the particles and microorganisms (only 30-70% removal efficiency)
• A good schmutzdecke will remove 90-99% of biological pathogens
• It may take 10 – 20 days to establish the schmutzdecke
• The water from the filter can be used during the first few weeks while the schmutzdecke is being established if a safer water source is not available, but chlorination is recommended at least during this time period
• The schmutzdecke is NOT usually visible – it is not a green slimy coating on top of the sand
DAILY USE
Educate all of the users, including children, on how and why the filter works and on the correct operation and maintenance. Children are frequently the main users of the filter.
• Slowly pour raw (untreated) water into the filter daily (at least 20 litres, twice per day)
• Using the same source of water every day will improve the filter effectiveness
• Use the best source of water (least contaminated) available – the better the raw water is, the better the treated water will be
• Pre-filter or settle raw water if not relatively clear – less than 50 NTU
Tip: A simple test to measure the turbidity is to fill a 2 litre clear plastic soft drink bottle with raw water. Place the bottle on top of large print such as the CAWST logo on this manual. If you can see the logo, the water probably has a turbidity of less than 50 NTU.
• The diffuser must always be in place when pouring water into the filter – never pour water directly onto the sand layer
• The lid should always be kept on the filter
• Use a designated bucket for fetching raw water
• Use a designated safe storage container to hold the treated water which has:
_ a small opening to prevent recontamination due to dipping with cups or hands
_ a tap or spigot
• Place the receiving container as close to the spout as possible (i.e. place it on a block) to reduce dripping noise and prevent recontamination
Note: The dripping noise can be irritating. The closer you place the container to the spout, the less dripping noise there is. A container with a small opening also reduces dripping noise.
• Water must always be allowed to flow freely from the filter – never plug the spout or connect a hose to it
Note: Plugging the spout could increase the water level in the filter, which could kill the biolayer due to lack of oxygen. Putting a hose or other device on the spout can siphon or drain the water in the filter, dropping the water level below the sand layer.
• No food should be stored inside the filter
Note: Some users want to store their food on the diffuser plate because it is a cool location. The water in the top of the filter is contaminated, so it will contaminate the food. Also, the food attracts insects to the filter.
• The treated water should be chlorinated after it passes through the filter to ensure the highest quality of water and to prevent recontamination (1-5 drops/litre or up to 1 teaspoon/gallon)
MAINTENANCE
Once a filter has been built, installed, and is operational, though minimal, there is some key maintenance that is required. The two primary requirements are disinfecting the spout and cleaning the biolayer when the flow rate is insufficient. Follow-up visits to ensure proper use and maintenance of the filters should be built into the hygiene education program.
DISINFECTION
• The spout will become contaminated during normal use via dirty hands, animals, or insects
• Clean the the spout every day with soap and water or a chlorine cleaning solution
• Wash the receiving container every second day with soap and water or a chlorine cleaning solution
• Do NOT pour chlorine bleach into the top of the filter!
• The entire filter should be cleaned regularly (lid, diffuser, outside surfaces)
SWIRL & DUMP
The flow rate through the filter will decrease over time as the schmutzdecke develops and fine particles are trapped in the upper layer of the sand. Users will know when the “swirl & dump” is required because the flow rate will drop to an unacceptable level. The filter is still effectively treating the water at this point; however the length of time that it takes to get a bucket of water may become too long and be inconvenient for the user. Alternately, you can measure the flow rate (as above) and if it is less than 0.3 litres/minute, “swirl & dump” maintenance is required.
1. Remove the lid of the filter.
2. Add 4 litres (1 gallon) of water to the top of the filter.
3. Remove the diffuser.
4. “Swirl” your hand around in the standing water at least 5 times – the water will become dirty. You can insert your fingers up to the first knuckle in the sand layer while “swirling” around across the entire surface area of the sand, but do not mix the surface layer deep into the filter.
5. Scoop out some dirty water with a small container (i.e. a cup or a pop bottle cut in half).
6. Discard the dirty water outside the house in an appropriate location (remember it is contaminated water).
7. Repeat this “swirl and dump” technique until all the water has been dumped out of the filter.
8. Replace the diffuser.
9. Pour 20 litres (5 gallons) of water into the top of the filter.
10. Measure the flow rate (as above).
11. Repeat steps 1 through 10 until the flow rate is acceptable (close to 1 litre/minute).
12. Wash your hands with soap and clean water - you have been handling contaminated water.
FOLLOW UP VISITS
Follow up with the users on a regular basis to ensure that the filter is being used properly. The first follow up visit should be during the first two weeks of use and then every 1-2 months thereafter. During follow up visits, ensure that the filter is being operated and maintained as described above. The following general checks can be made at any time by the users, a community health worker, or a filter technician that is active in the area:
• Check that the filter is in an appropriate location (indoors, protected from the weather, animals, and insects) and is level
• Look for drips of water or wet spots under the filter, which indicate a leak in the concrete box
• Check that the lid is tight fitting and clean on the inside and outside
• Make sure the diffuser is clean and is sitting properly on the concrete lip
• Make sure the holes in the diffuser are not plugged – periodic cleaning may be needed
• Check that the surface of the sand is smooth and level (use a small straight object to smooth the sand ONLY if necessary)
• Make sure the surface of the sand is 2” (5cm) below the water level.
Note: the sand may settle over time and more will have to be added. Add (or remove) sand if the standing water depth is not 2”.
#12, 2916 – 5th Ave N.E.
Calgary, Alberta, Canada T2A 6K4
Telephone: (403) 243-3285
Fax: (403) 243-6199
Email:
cawst@cawst.org
Website:
www.cawst.org
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http://www.nationalterroralert.com/safewater/
Emergency Water Storage
Having an ample supply of safe, clean water is a top priority in an emergency. A normally active person needs to drink at least two quarts of water each day. Hot environments can double that amount. Children, nursing mothers and ill people will need even more. You will also need water for food preparation and hygiene. Store a total of at least one gallon per person, per day. You should store at least a two-week supply of water for each member of your family. If supplies run low, never ration water. Drink the amount you need today, and try to find more for tomorrow. You can minimize the amount of water your body needs by reducing activity and staying cool.
Amount of Water to Store
Whereas a quart of water or other fluid daily will sustain life, according to the Department of Defense and the Office of Civil Defense, it is recommended that a gallon of water per day per person be stored for food preparation and drinking. A gallon provides added comfort and accommodates increased fluid needs at higher altitudes or warm climates. An additional one-half to 1 gallon per day is recommended for bathing and hygiene, and to wash dishes. How much water should I store? The rule of thumb is to store at least one gallon per person per day for at least 3 days (for earthquake preparedness). That’s 2 quarts for drinking and 2 quarts for food preparation and sanitation. A family of four should store a minimum of 12 gallons of water. Personally, I recommend at least a 10 day supply of water and a 30 day supply if it all possible. Use the following guidelines when storing water: 1. Store drinking water in carefully cleaned, non-corrosive, tightly covered containers. 2. Store containers in a cool dark place. DO NOT store in direct sunlight. Polyethylene plastics (prepackaged milk and water bottles) are somewhat permeable to hydrocarbon vapors. Keep away from stored gasoline, kerosene, pesticides, or similar substances. 3. Stored tap water should be rotated every 6 months. Prepackaged bottled water should be rotated once a year. Check the pull date on the container. Be sure it didn’t sit on the store’s shelf for a year before you purchased it. Self Serve Bottled Water should be rotated once a year, as long as the water treatment process includes ozonation. 4. Rotate your stored water with the water you use on a regular basis. This practice helps insure you don’t have water stored longer than one year.
Containers That Can be Used for Water Storage
Food-grade plastic or glass containers are suitable for storing water. One-, three- and five-gallon water containers can be purchased from most outdoor or hardware stores. Any plastic or glass container that previously held food or beverages such as 2-liter soda bottles or water, juice, punch or milk jugs, also may be used. Stainless steel can be used to store water which has not been or will not be treated with chlorine; chlorine is corrosive to most metals. 55 gal drums, designed specifiacally for water storage can be difficult to transport, if the need arises, but are of a tremendous value in an emergency .When looking for additional food grade containers, the bottom will be stamped with HDPE (High Density PolyEthylene) and coded with the recycle symbol and a “2″ inside. HDPE containers are FDA-approved for food. Containers without these designations aren’t OK because of possible chemical interactions between the water and the plastic. Clean used containers and lids with hot soapy water. Once the containers have been thoroughly cleaned, rinse them with water and sanitize the containers and lids by rinsing them with a solution of 1 tablespoon chlorine bleach per gallon of water. Leave the containers wet for two minutes, then rinse them again with water. Remember to remove the paper or plastic lid liners before washing the lids. It is very difficult to effectively remove all residue from many containers, so carefully clean hard-to-reach places like the handles of milk jugs. To sanitize stainless steel containers, place the container in boiling water for 10 minutes. Never use containers that previously held chemicals.
Do I Need to Treat Water?
Once you properly clean containers, fill them with potable, or safe, drinking water. All public water supplies are already treated and should be free of harmful bacteria. However, as an additional precaution, it is recommended that you add 5-7 drops, about 1/8 teaspoon, of chlorine bleach per gallon of water stored. This precaution protects you against any lingering organisms in storage containers that may have been inadvertently missed during the cleaning process.
Where to Store Water
Clearly label all water containers “drinking water” with the current date. Store the water in a cool, dry place away from direct sunlight and heat sources. Do not store it near gasoline, kerosene, pesticides or similar substances. When potable water is properly stored, it should have an indefinite shelf life; however, it’s a good idea to use and replace the stored water every 6 - 12 months. Rotating water this way provides you with an opportunity to experiment and check the amount of stored water against what you require. It also serves as an additional precaution against bacteria or viruses growing in containers which may not have been thoroughly or properly cleaned and sanitized. If you have freezer space, storing some water in the freezer is a good idea. If you lose electricity, the frozen water will help keep foods in your freezer frozen until the power is restored. Make sure you leave 2 to 3 inches of space in containers because water expands as it freezes.
Emergency Sources of Water
In an emergency, if you have not previously stored water and commercial or public sources of water are not available, drain water from your plumbing system. Unless you are advised that the public water supply has been contaminated and is not safe, open the drain valve at the bottom of the water heater and salvage the water stored in the heater. A typical water heater holds 30-60 gallons of water. Discard the first few gallons if they contain rust or sediment. Let the water heater cool before draining it from the heater so it does not scald you. Turn off the electricity or gas to the water heater to prevent the heater from operating without water. Once water has been drained into clean, sanitized containers, add 5-7 drops of chlorine bleach* per gallon of water, and stir or shake the solution to mix it. Let it set 30 minutes before use. Emergency Outdoor Water Sources If you need to find water outside your home, you can use these sources. Be sure to treat the water first. Additional sources include: Rainwater Streams, rivers and other moving bodies of water Ponds and lakes Natural springs Avoid water with floating material, an odor or dark color. Use saltwater only if you distill it first. You should not drink flood water. Hidden Water Sources in Your Home If a disaster catches you without a stored supply of clean water, you can use the water in your hot-water tank, pipes and ice cubes. As a last resort, you can use water in the reservoir tank of your toilet (not the bowl). Do you know the location of your incoming water valve? You’ll need to shut it off to stop contaminated water from entering your home if you hear reports of broken water or sewage lines. To use the water in your pipes, let air into the plumbing by turning on the faucet in your house at the highest level. A small amount of water will trickle out. Then obtain water from the lowest faucet in the house. To use the water in your hot-water tank, be sure the electricity or gas is off, and open the drain at the bottom of the tank. Start the water flowing by turning off the water intake valve and turning on a hot-water faucet. Do not turn on the gas or electricity when the tank is empty. Using Swimming Pool Water You should always view your pool as “backup” water; keep the water treated; you never know when it will be needed! The maintenance of the free chlorine residual will prevent establishment of any microorganisms. The maintenance level should be kept about 3-5ppm free chlorine. (See Water Purification for detailed information on purifying pool water.) If other stored water stocks are not available, remove the necessary pool water and boil it or just treat with chlorine to the normal 5ppm. It is best to err on the side of caution. Covering the pool at all times when not in use is a very good idea. Try to keep the cover clean and wash the area you put it on when removing it from the pool.
When and How to Treat Water for Storage
In an emergency, if you do not have water that you know is safe, it’s possible to purify water for drinking. Start with the cleanest water you can find and treat with one of the following methods:
*
Boiling and chlorinating: Water can be purified by boiling. Boiling times may vary from state to state, depending on altitude. In Colorado, the water is safe to use once after it has been boiled for three to five minutes and has cooled. If you plan to store boiled water, pour it into clean, sanitized containers and let it cool to room temperature. Then add 5-7 drops, or 1/8 teaspoon, of chlorine bleach* per gallon of water (1/2 teaspoon per 5 gallons). Stir or shake the solution to mix it. Cap the containers and store them in a cool, dry place.
*
Filtering and chlorinating: You can filter water if you have a commercial or backpack filter that filters to 1 micron. These are available in sporting good stores and are recommended for use when back-packing. They are not recommended to clean large volumes of water. Filtering eliminates parasites such as giardia and cryptosporidium, but it may not eliminate all bacteria and viruses. Therefore, it’s recommended that 5-7 drops (1/8 teaspoon) of chlorine bleach* be added per gallon of filtered water (1/2 teaspoon for 5 gallons). Stir or shake the solution to mix it. Wait 30 minutes before using the water, or cap the containers and store them in a cool, dry place.
*Use liquid household bleach that contains 5.25 percent hypochlorite. Do not use bleaches with fresheners or scents as they may not be safe to consume. The above treatment methods use a two-step approach so less bleach is needed, yet giardia and cryptosporidium are destroyed through boiling or eliminated by filtering. Chlorine may not be effective against these parasites.
Since adding too much chlorine to water can be harmful, it’s important to be as accurate as possible when measuring.
*
Distillation Distillation involves boiling water and then collecting the vapor that condenses back to water. The condensed vapor will not include salt and other impurities. To distill, fill a pot halfway with water. Tie a cup to the handle on the pot’s lid so that the cup will hang right-side-up when the lid is upside-down (make sure the cup is not dangling into the water) and boil the water for 20 minutes. The water that drips from the lid into the cup is distilled.
Most water filtration devices are designed for use on microbiologically safe water. Don’t assume they are safe to use on contaminated water. Check with the manufacturer to be sure. Use the following guidelines to determine if filtration equipment is adequate to use with microbiologically contaminated water:
Filtration Equipment
Safe on Microbiologically Contaminated Water?
Carbon Filter No
Reverse Osmosis No
Deionization Filter No
Pitcher Filter No
Faucet Mount Filter No
Steam Distiller Yes - but requires electricity
UV Sterilizer Yes - but requires electricity
Ceramic Filter Some - but only if rated for bacteriological protection
Equipment that is safe to use on contaminated water is often slow, costly, inconvenient and/or high maintenance.
It makes the most sense to use the filtration equipment that best meets your normal daily needs and shift to water storage or alternative methods of water treatment in times of emergencies.