Module 2

Module

2.2 2.2 Filter Construction

This module contains material relating to the construction of the BioSand Concrete filter. It is meant as a supplement to hands-on training by a qualified instructor. An aid to this module is the colour booklets contained in the Appendices that illustrate the various aspects of building the filter.

Module 2.2 Filter Construction 2.2 FILTER CONSTRUCTION............................................................................................. ......1 SAFETY HAZARDS..............................................................................................................................2 Cement and Concrete....................................................................................... .......................3 Bleach...................................................................................................................................... 3 Tools......................................................................................................................... ...............4 Housekeeping....................................................................................................... ...................4 Injuries................................................................................................................. ...................4 Water Samples........................................................................................................ .................4 First Aid Kit.......................................................................................................................... ...4 CURRENT MOLD DESIGN....................................................................................................................5 FILTER TOOL KIT..............................................................................................................................5 Tools......................................................................................................................... ...............5 Supplemental items........................................................................................................... .......6 MATERIAL LIST FOR CONCRETE FILTER TRAINING..................................................................................7 Tool Kit............................................................................................................................ ........7 Media Sieves – for 3 sieves............................................................................................... .......7 Concrete Filter .................................................................................................. .....................8 Filter Media ................................................................................................ ...........................8 Filter Lids and Diffuser Basins .............................................................................................. .8 APPENDICES......................................................................................................................................8 Appendix C: Steel Mold Drawings.................................................................... ......................8 Appendix D: Steel Mold Fabrication Instructions.................................................... ...............8 Appendix E: Sieve Set Construction Manual......................................................... ..................8 Appendix F: Media Preparation Manual.............................................................................. ...8 Appendix G: Concrete Filter Construction Manual............................................................... ..8 Appendix H: Diffusers and Lids Manual............................................................. ....................8 Appendix I: Installation Operation & Maintenance Manual..................................... ..............8

Safety Hazards It is important to work safely to avoid the potential for injuries while constructing a BioSand filter. When building the filter, you will be using sharp tools, lifting heavy pieces and handling potentially dangerous materials. When properly managed, the risks involved in these tasks can be reduced to avoid injuries. There are hazards that are present when constructing a concrete biosand filter. Participants should be aware of these hazards and be cognisant of them as they proceed. The following are hazards when building a filter: • Handling of potentially dangerous materials such as cement powder, wet concrete and bleach or sanitizing solution • Incorrect use of tools – especially sharp tools • Messy work spaces • Heavy objects – filter mold, sand bags, cement bags, finished filter, water pails

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Module 2.2 Filter Construction Cement and Concrete Cement is a light gray powder made of a mixture of calcined limestone and clay; used with water and sand or gravel to make concrete and mortar. Concrete is a light gray fluid mixture that poses an immediate hazard to eye tissue. Exposure of sufficient duration to wet concrete can cause serious, potentially irreversible tissue (skin or eye) destruction in the form of chemical (caustic) burns, including third degree burns. A person can work with wet cement on the skin for hours without feeling any discomfort. But the alkaline burn of the cement is damaging the skin microscopically. That damage may be just a cement burn or it also may be the cumulative injury that leads to irritant or allergic dermatitis. There should be no need to handle or even touch the dry or wet concrete when building the filter. However, there are precautions that should be taken. 1. Wear gloves 2. Wash with clean running water and pH-neutral soap. 3. Remove hand jewellery. 4. Long sleeves should be buttoned and placed inside gloves. 5. Never let cement remain on skin or clothes. 6. Wear safety glasses to protect eyes. 7. See a doctor for any persistent skin problem. To learn more about safe handling of cement and concrete, please check these web sites: http://www.cdc.gov/elcosh/docs/hazard/chemical_cement.html (Apr 05) http://www.lehighinland.com/NR/rdonlyres/61D17AB6-905F-4E93-B554A4DC553A5BDF/0/ConcreteMSDS1.pdf (Apr 05)

Bleach Bleach is produced by reacting chlorine into a dilute sodium hydroxide solution. Bleach is used for whitening paper, soap, straw and cotton, and for disinfection, water purification and in sanitary cleaners. It is available in various forms and in varying concentrations. For example laundry bleach is about 5-6 % available chlorine whereas pool chlorine is 12 % available chlorine. AVOID EYE & SKIN CONTACT & INHALATION OF VAPOR OR MIST Skin Contact - may cause irritation unless rinsed immediately Eye Contact - may cause inflammation of mucous membranes in throat, nose and lungs First Aid Skin Contact - remove from area and flush with large amounts of water. Remove contaminated clothing and wash before reuse. Eye Contact - flush with water for at least 15 minutes lifting upper and lower lids occasionally. Get medical attention

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Module 2.2 Filter Construction These are two web sites that have MSDS (Material Safety Data Sheet) for bleach. http://www.biosci.ohio-state.edu/~jsmith/MSDS/CLOROX%20LIQUID%20BLEACH.htm (Apr 05) http://www.safety.vanderbilt.edu/pdf/hcs_msds/cloroxbleach.pdf (Apr 05)

Tools While all of the tools used to construct the filter are small hand tools, they still have a potential to cause injury. Storing and using the tools correctly is the best way to prevent injuries. Use caution with sharp tools (saws, tin snips and knives) to prevent cuts. Sharp edges of metal sheets can also cause cuts. Be aware of smashing and crushing injuries to hands when using hammers and wrenches. Housekeeping Building the filter can be a messy job! Encourage the workers to clean up the work place frequently and continuously. If the site is always kept clean, there will never be a need for a big clean up job at the end of the day or week. Replace tools back in the storage place or tool box. Wipe up spills of water, concrete and oil as soon as they occur. A slippery floor can result in a nasty fall. Clean tools as soon as practical once they have been used. Large amounts of dried concrete on a shovel can make it useless. Keep lab and water testing areas extremely clean. Injuries Accidents may result in injuries due to several causes. Cuts and bruises to fingers or hands may occur when using the hand tools. Crushed or pinched fingers may happen when handling the mold, wheel barrows, shovel and heavy tools. Burns from cement, concrete or bleach may result from poor practices. Strained muscles in the back, shoulders and arms may occur from lifting, bending or shovelling too much sand or concrete. Use extreme caution when moving or handling the filter mold or finished concrete filter. The best protection against injuries is to prevent them in the first place. Wear appropriate clothing. Use correct procedures. Keep the work place clean. Water Samples Contaminated water samples may contain high amount of bacteria which could be potential hazardous to your health. Disinfect work areas frequently. Dispose of water samples appropriately. Place used membrane filter papers in a bleach solution and then dispose in an appropriate garbage container. First Aid Kit The work place should have a first aid kit available at all time. As a minimum, this should be stocked with band aids and disinfectant materials. Medical assistance contact numbers should be readily available. In most North American locations, the emergency phone number is 9-1-1.

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Module 2.2 Filter Construction

Current Mold Design The Version 9.0 filter design was introduced for several reasons, including feedback from our clients who wanted a lighter filter. This mold is lighter than previous versions because less steel is used, reducing material costs. The back and side walls of the exterior mold are welded together rather than bolted, since many users were not undoing those bolts anyway. The resulting filter has much thinner walls and base, reducing the amount of materials used. The outcome is a reduction in the weight of the finished filter (160 Lbs as opposed to 330 Lbs), and importantly, a reduction in the cost per unit of produced filters, making them more affordable for poor families and making filter construction micro enterprises more profitable. A different concrete mixture is used for these small filters than for the previous design, to increase the strength of the thinner walls. Also, PVC pipe cannot be used for the standpipe as the fittings are too wide to fit inside the wall. Thus, bent copper or plastic tubing is used for the standpipe. The steel mold that is used for the BioSand filter is designed to produce a good final product, while being easy to use. The filter has gone through eight generations of improvements, but there may still be revisions that would add value. With good care and maintenance, this mold should be suitable for several years of filter construction.

Filter Tool Kit A good set of tools is needed to easily and properly construct a BioSand filter. These are all hand tools and, if maintained and handled properly, will provide many years of useful life. Tools The following tools are needed for constructing the sand sieves, lids and diffusers: • Nails – 1 and 2 inch coated - used to build sieve sets, diffuser and lid • Sand Paper – to clean up rough edges of wood • Tape measure – for measuring things! • T-square – to lay out square lines when cutting the wood • Hand saw – for cutting wood pieces – sieves, lid, diffuser • Hammer – for nailing the wood together • Tin snips – to cut the galvanized metal for the diffuser • Utility knife – to cut plastic cardboard diffuser • Acrylic cutter knife – to cut acrylic plastic if used for diffuser (Power saw may be used if available) • Staples – optional – for attaching screen to the sieve frames • Wire – optional – to hold screen or other things together

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Module 2.2 Filter Construction • •

Hand drill and bits – optional – for drilling starter holes if the wood is susceptible to cracking, to drill holes for handles on the sieves Flat headed screw driver – optional - to fix your truck

The following tools are needed for constructing the concrete filter: • Wire Brush and scraper - used for cleaning up the steel filter mold • Sand paper – used for cleaning up the steel filter mold. • 3 inch paint brush (optional) - for applying oil to steel filter – rags may be used instead • Paint brush for painting the completed filter if desired • Hack saw with spare blades – for cutting copper pipe • Tubing / Pipe cutters - to cut 3/8 “ copper tubing • 3/8” tubing bender – specialized tool for bending copper pipe • Trowel (optional) – to level the concrete on the top of the mold, a small piece of wood can be used instead • Two – 9/16 inch open/box end wrenches – to tighten/loosen bolts holding the filter mold together (a 9/16 inch socket set may also be used). • Level – to ensure that the mold is level before you pour the concrete • Rubber hammer – to beat on the side of the mold when the concrete is settling (get out the air bubbles) and when preparing to take the mold off once the concrete has cured1 ½ inch open/box end wrench – use with puller assembly to remove inner mold from the filter • Tool Box – to hold everything! This could be a commercially fabricated metal box or it could be a hand made, wooden box or alternative. Supplemental items • Coarse bristle brush – to clean up the filter mold • 1” scraper – to clean up filter mold • Small Bucket or container - to hold studs and nuts from filter mold • 4 foot (2” diameter) hollow steel pipe – to user as a “cheater” on the 1 ½ inch wrench when taking apart the mold • A 1 litre measurement container – small plastic container marked at one litre volume • 4-6 pails for washing sand, carrying gravel, cement, water • Wheel barrow – hauling sand, mixing cement • Shovels – handling sand and cement • Rubber gloves – for washing gravel, handling concrete • Leather gloves – for handling sheet metal, general labour (for those with soft office hands!)

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Module 2.2 Filter Construction

Material List for Concrete Filter Training Tool Kit Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Description

1 ½” combination wrench 9/16” combination wrenches or socket set 6” slip joint pliers (optional) Hack saw with blades Utility knife Tubing bender Tubing / pipe cutter Wire brush Measuring tape Hand saw Masonry trowel (optional) 2” paint brush (optional) Hand level (optional) T square Fine sand paper - package Rubber mallet Claw hammer 2” galvanized nails – package 1” galvanized nails – package Tool box Shovels Pails – 20 liter Measuring container (1 liter pop bottle) Water hose (25 ft) Plastic sheeting or tarps Rags, paper towels Black marker / pencils 1” scraper Rubber gloves – pairs Wheel barrow Bleach – household, 1 litre bottle

Quantity for one group

Approximate Cost $ CDN

1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 4 1 1 1 5 1 1 2 1 1

40 12 6 25 9 15 8 3 6 18 8 4 9 8 3 12 14 4 3 24 15 16 2 12 12 3 2 4 10 75 4

Media Sieves – for 3 sieves Lumber 1” x 4” (or 3”) x 8’ Lumber 1” x 1” x 8’ strapping 2x2 hardware cloth (2 squares per inch-each direction) Comes in rolls either 24” or 36” 4x4 hardware cloth (4 squares per inch, each direction) Comes in rolls either 24” or 36” Metal mosquito screening – 14 or 15 gauge – 14 wires per inch- comes in 24” or 36” widths

3 pieces 3 pieces 8 ft2

$9 7 2

4 ft2

2

4 ft2

2

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Module 2.2 Filter Construction

Concrete Filter Portland cement Sand for concrete Gravel for concrete (screened to ¼”) 3/8 ” copper tubing Vegetable oil

1 - 40 kg bag 1 ft3 1 ft3 3 ft 500 ml

$8

1/2 cubic yard

$10

4 ft2

$3

4 2

Filter Media Crushed rock and sand – ½” minus – construction grade, mixed material, include fines, unwashed - this material is also used for the concrete sand/gravel

Filter Lids and Diffuser Basins Galvanized sheet metal – 24 gauge 12” minimum width OR 1 sheet plastic cardboard (4’ x 8’ - makes 32 diffusers) OR 1 Sheet plexiglass or stiff plastic 24” x 48” (makes 8 diffusers)

12 24

Appendices Appendix C: Steel Mold Drawings Appendix D: Steel Mold Fabrication Instructions Appendix E: Sieve Set Construction Manual Appendix F: Media Preparation Manual Appendix G: Concrete Filter Construction Manual Appendix H: Diffusers and Lids Manual Appendix I: Installation Operation & Maintenance Manual

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