Difference between revisions of "The WATA device"

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{{Language-box|english_link= The WATA device | french_link= Coming soon | spanish_link= Coming soon | hindi_link= Coming soon | malayalam_link= Coming soon | tamil_link= Coming soon | swahili_link=coming soon | korean_link= Coming soon | chinese_link=WATA设备 | indonesian_link= Coming soon | japanese_link= Coming soon }}
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[[Image:safe_water_systems_icon.png|right]]
 
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[[Image:setup of WATAsol.jpg|thumb|right|250px|Setup of WATAsol, with electrodes in salt water.]]
 
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[[Image:Bubbles.jpg|thumb|right|250px|Bubbles produced during electrolysis.]]
 
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[[Image:Line of products.jpg|thumb|right|250px|Line of products: from left to right the mini-WATA, reugular WATA and Maxi-WATA]]
 
  
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The Watasol is simple a device which produces active chlorine from salt water using electrolysis. The device consists of two tungsten electrodes in a plastic container, and a transformer. The active chlorine forms hydrochloric acid when added to water. As the active chlorine has a very strong oxidizing power, is destroys almost all pathogenic germs including diarrhoeal diseases, dysentery, cholera, typhoid fever, salmonellosis and hepatitis A.
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[[Image:Tinkisso tem with bottles.png |thumb|200px|[https://www.antenna.ch/en/water-hygiene/guinea/ Tinkisso-Antenna] employees in Guinea holding Maxi-WATA devices.]]
  
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The WATA device and its use was designed by [http://www.antenna.ch/en/drinking-water.html Antenna Technologies] based on the norms of the World Health organization on for example the accepted quality of water, amount of chlorine needed to disinfect 1L of water and the acceptable amount of free residual chlorine.  
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The WATA device makes use of the simple process of electrolysis (electrochlorination) to produce sodium hypochlorite at a concentration of 5 grams per liter using only salt and water as inputs. As the active chlorine has a strong oxidizing power, it effectively inactivates the vast majority of disease-causing bacteria and viruses.  
  
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When chlorine is added to water, it has three separate effects:
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Chlorine began to be widely used as a disinfectant in the early 1900’s. It revolutionized drinking water treatment and dramatically reduced the incidence of waterborne diseases. In many countries, including the United States, chlorine remains the most widely used chemical for water disinfection.
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# Some chlorine reacts through oxidation with organic matter and pathogens in the water and kills them. This portion is called consumed chlorine.
 
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# Some chlorine reacts with other organic matter and forms new chlorine compounds.  This portion is called combined chlorine.
 
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# Excess chlorine that is not consumed or combined remains in the water. This portion is called free residual chlorine (FRC). The free residual chlorine helps prevent recontamination of the treated water.
 
  
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Chlorine began to be widely used as a disinfectant in the early 1900’s. It revolutionized drinking water treatment and dramatically reduced the incidence of waterborne diseases. In many countries, among which the United States, chlorine remains the most widely used chemical for water disinfection.  
+
Sodium hypochlorite is one form of chlorine used for water disinfection. It can be manufactured in remote locations since it can be obtained through the electrolysis of salt water. In bottles of sodium hypochlorite in a wide range of sizes can be purchased from a variety of vendors in countries around the world. Chlorine concentrations range from 0.5 to 10% and each product has its own instructions for correct dosing of contaminated water. One common product containing sodium hypochlorite is liquid household bleach.
  
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Sodium hypochlorite is one form of chlorine used for water disinfection. It can be manufactured in most locations since it can be obtained through the electrolysis of salt water. Bottles can be purchased for household water treatment from many manufacturers in various sizes. Chlorine concentrations range from 0.5 to 10% and each product has its own instructions for correct dosing of contaminated water.  Liquid household bleach also contains sodium hypochlorite, and is widely available.
+
The problem is that in many developing countries chlorine is imported rather than produced locally. This steeply increased the price of chlorine for the user as it adds transportation, storage, and other related costs. In addition, the quality of the sodium hypochlorite, like with many other products, degrades in quality over the course of improper handling and storage over the course of long transportation times. The WATA range devices, developed by Antenna Foundation, allows chlorine to be produced locally to provide chlorine disinfectants for individual households, health centres and hospitals, and emergency relief.
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The problem is that in many developing countries, chlorine is imported, rather than produced locally. This increases the price tremendously as it adds transportation, storage, and other related costs. Often also the source and transportation is not reliable in certain remote areas. The WATAsol devices, developed by [http://www.antenna.ch/en/drinking-water.html Antenna Technologies] allow chlorine to be produced locally, on different scales to provide chlorine disinfectants for individual households, health centres and hospitals, and emergency relief.
 
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WATAsol is now being produced in around 50 countries. It reaches the people in need through local NGOs, and local community and private enterprises. Starting from 2009, Antenna Technologies is hoping to expand their reach further through partnership-franchises with local enterprises as partners. The WATAsol has also been incorporated in development programmes led by other organizations. 
 
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==Suitable Conditions==
 
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The concentrate is suitable for various applications:
 
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* To wash food: 1 part concentrate is diluted with 100 parts water. It needs 5 minutes to react, after which the food should be rinsed with drinking water.
 
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* To clean dishes, kitchen utensils, work surfaces: 1 part concentrate is diluted with 5 parts water. It takes 5 minutes to react, after which it is rinsed with drinking water.
 
−
* To clean floors, bathrooms or latrines: 1 part concentrate is diluted with 3 parts water. It needs 5 minutes to react, after which it is rinsed with drinking water.
 
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* To disinfect pipettes, tubes or other laboratory equipment: 1 part concentrate is diluted with 1 part water. It needs at least 12 hours to react, after which it should be rinsed with drinking water. 
 
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The concentrate can be used for disinfection of barns, cow sheds and their waste water, clothes and fabrics, gutters and roads, and treatment of mycosis fungicides. Though it can be used for the disinfection of surgical equipment, it must be noted that it cannot be used to sterilize these. They must be sterilized in an autoclave or a dry-heat sterilizer.  
 
  
 +
Active chlorine solution is being produced using the WATA range of devices in over 100 countries. It reaches people in need through local NGOs and community groups, international organizations, municipal authorities and private enterprises. Since the WATA range of devices was first launched in 2009, Antenna Foundation is hoping to expand their reach further through partnerships, especially with local enterprises. The WATA devices have also been incorporated into development programmes led by other organizations.
  
 
{| border="1" cellpadding="5" cellspacing="0" align="center"
 
{| border="1" cellpadding="5" cellspacing="0" align="center"
 
|-
 
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! width="50%" style="background:#efefef;" | Advantages
 
! width="50%" style="background:#efefef;" | Advantages
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! style="background:#ffdead;" | Disadvantages
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! style="background:#f0f8ff;" | Disadvantages
 
|-
 
|-
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| valign="top" | -It allows for the local production of active chlorine, which is much cheaper than importing bleach tablets or other forms of chlorine, as it saves on import tariffs, transportation and storage costs. <br>
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| valign="top" | - Local production (avoids most storage and transportation problems and environment impacts. <br>
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- The local production also creates employment and local development opportunities. For example, the chlorine concentrate produced can be sold to local health clinics, etc. for cleaning of equipment. <br>
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- Generation of income for local communities as the local production also creates employment and local development opportunities. <br>
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- It is very simple<br>
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- Solar versions available for autonomous use. <br>
−
- It is very robust and designed to suit the field conditions in developing countries <br>  
+
- Quality control is possible at every stage of production and use. <br>  
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- It comes with a line of products, allowing it to be used on different scales, for different numbers of people and allowing quality control at every step of production. <br>
+
- Low cost <br>
−
- It is very sustainable and is guaranteed to last for at least 20000 hours. <br>
+
- Especially suitable for humanitarian response or where armed conflict has led to an embargo on chlorine gas and powder.<br>
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- It has applications other than the disinfection of water, such as the disinfection of tools, utensils, and even wounds. <br>
+
- Easy to use. <br>
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- The concentrate produced is less toxic than bleach an therefore safer and more user friendly.<br>
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- Can be used as a disinfectant for a large range of applications (e.g. disinfecting laboratory equipment, wounds, cleaning latrines, disinfecting kitchen utensils and surfaces, washing rough fruits and vegetables etc.).<br>
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| valign="top" | - The chlorine concentrate cannot eliminate contamination from chemical pollutants such as pesticides, fertilizers, or heavy metals.<br>
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| valign="top" | - Electricity required (but can be run with solar energy)<br>
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- When used on surgical equipment, it does not fully sterilize these, but it does disinfect. <br>
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- Education and training for operators are essentials, especially when using Maxi- WATA. <br>
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- Users must receive clear instructions, to avoid using a wrong doseage.
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- Chlorination can cause the generation of a very low concentration of toxic disinfection by-products (DBPs) in the case of disinfecting water with a high organic matter content.<br>
−
- Raw water for both chlorine production and for drinking water purpose should be considerably clear, so that WATA kit and the chlorine take effects, respectively <br>
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- Dosage might more difficult than with tablets <br>
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- The device must only be used by adults <br>
+
- Only clear water can be used to produce WATA solution and the solution is only effective in treating clear water <br>
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- WATA maxi needs connection to electricity grid <br>
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- The device should only be used by a responsible person familiar with the user manual for the relevant WATA device.<br>
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- Not ready drinkable since people should wait for 30 minutes after the treatment process <br>
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- Requires wating 30 minutes after treatment before the water is ready for consumption. <br>
 +
- Chlorine taste and smell
 
|}
 
|}
  
  
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==Construction, operations and maintenance==
+
====The WATA Range of Devices====
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The effectiveness of chlorine depends on the turbidity, the organic matter content, the temperature and the pH of the water being treated. For high turbidity levels, the water should first be filtered through a cloth or sedimented before adding chlorine. These processes will remove some of the suspended particles and improve the reaction between the chlorine and pathogens.
+
[[File:WATA Range.jpg|thumb|200x200px|[https://www.antenna.ch/en/activities/water-hygiene/range-wata/ The range of WATA devices] and reagents]]
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+
The device comes in four models for different scales of chlorine production: Mini-WATA (0.5L of solution), WATA-Standard (2L of solution), WATA-Plus (15L of solution) and Maxi-WATA (60L of solution). The Mini-WATA, the WATA-Standard and the WATA-Plus are all capable of running off of a solar energy source allowing them to be deployed in regions that lack stable access to electricity. The devices take 2 hours to convert the brine solution to active chlorine solution. Once the process is finished, one litre of that solution is good for disinfecting 5,000 litres of water.
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The device comes in three types, to be used for different scales of chlorine production: the WATA kit, the mini-WATA and the maxi-WATA. The mini-WATA is a variation of the WATAsol that fits into a regular water bottle. It produces active chlorine to treat up to 4800 litres of water per day, which is enough clean water for the daily needs of 240 people. It can run on 5V/1A but requires a minimum of 10W. The regular WATA produces enough water to treat 48,000 litres of water per day, providing clean water for 2400 people. It runs on 12V/4A. The maxi-WATA produces chlorine to treat 720,000 litres of water, providing for 36,000 people. It runs on a 24V/30A electric network.  
 
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WATA devices can produce between 1.2 litres and 180 litres of active chlorine each day. Each litre of that solution is good for disinfecting 4,000 litres of water.  The regular WATAsol produces 1L/hr of active chlorine.  It is designed to produce 2-10L per procedure.  
 
  
 
=====Operation=====
 
=====Operation=====
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To produce the chlorine concentrate, first a salt solution needs to be made. If highly refined salt is used, this can be directly mixed with fresh water at a concentration of 25g/L and stirred until fully dissolved to produce the salt solution. If the salt is not fully refined, it is first made into saturated brine and then mixed into the solution to be electrolyzed at a concentration of 80ml/L; such that about 1/13 of the solution is brine. Both procedures lead to the same concentration of salt in the solution.
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[[Image:WATA Instructions.png|thumb|200px|Instructions to create the salt water solution to be transformed into sodium hypochlorite. Taken from the WATA manual]]
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The device should only be used by adults. The user guide should be carefully read before use. The chlorination however should be supervised by a qualified person.
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To prepare the brine, a (non-metallic) container is filled with clear water. A large amount of salt is added (about 400g per liter of water) and the mixture is shaken for half an hour till as much salt as possible is dissolved. To make sure the solution is saturated, there should be some salt remaining at the bottom of the container. If no excess salt is visible, more is added till the solution is saturated. This can then be mixed with the fresh water.
 
−
 
 
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Once the salt solution is ready, the WATA device is immersed. The body of the WATA should be completely covered by the solution but the stems should stick out above the surface.
 
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The power supply of the WATA device (of 110V or 220V) is plugged in. The device works on 12 V direct current. It can be plugged directly into a car battery, car battery charger or solar panel. A grid or diesel generator delivering alternating current can also be used with the provided transformer.
 
  
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If the electrolysis is occurring properly, bubbles are formed immediately. The electrolysis takes an hour per litre, producing a chlorine concentrate of 6g/L. The chlorine concentrate should be used within three weeks of production. Notable is that full containers last longer than half-empty ones, due to the effects of dissolving oxigen.  
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The only input needed for the production of sodium hypochlorite at 5 grams per liter is salt water at a concentration of 25 grams per liter. To arrive at this concentration, first prepare a brine and then mix 1 unit of brine for 3 units of clear water for the required amount of salt water. The amount of salt water needed for production varies by device.
 +
 +
To prepare the brine, a (non-metallic) container is filled with clear water. A large amount of salt is added (about 400g per liter of water) and the mixture is shaken for half an hour till as much salt as possible is dissolved. To make sure the solution is saturated, there should be some salt remaining at the bottom of the container. If no excess salt is visible, more is added till the solution is saturated. It can be stored for up to six months and can then be mixed with fresh water for production. The water used to prepare the brine solution also needs to be clear as high turbidity levels will interfere with the electrolysis process.
  
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=====Use=====
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Once the salt solution is ready, the WATA device should be totally immersed in the solution. Connect the WATA device to the power supply and turn on the machine. The amount of time it takes to The power supply of the WATA device (of 110V or 220V) is plugged in. The device works on 12 V direct current. It can be plugged directly into a car battery, car battery charger or solar panel. A grid or diesel generator delivering alternating current can also be used with the provided transformer.
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The chlorine concentrate is then added to the water to be disinfected. It should be shaken thoroughly and left for 30 minutes. There should be 0.5-1.0mg/L of residual chlorine left. The level of chlorine can be measured using the WATAblue reagent.  
 
  
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Especially if the chlorine concentrate is to be sold after production, it is useful to check the concentration of the active chlorine. This can be done using the WATATest reagent.
+
Active chlorine is very sensitive to light and degrades relatively quickly if not stabilized for long term storage. The stabilization process involves raising the pH of the chlorine solution and will allow it to be stored up to 3 months. It can be achieved with the WataStab reagent kit. If not stabilizing the solution should be used with 24 hours if disinfecting drinking water. It can be stored for longer if destined for cleaning purposes, although the concentration will deteriorate over time and it should be measured before use to ensure an adequate level of disinfection.
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The concentrate should be stored in the container provided, tightly closed and clearly labeled with the production date. It should be stored in a dark place, away from the sun. The container should be kept full if possible, since air will oxidize the concentrate.  
 
  
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The chlorine concentrate produced is not very dangerous, it is less toxic than bleach. In case of contact, rinse well with water. Inhalation could be dangerous. It should be kept away from children.  
+
====Use for Water Disinfection====
 +
[[Image:Tinkisso team holding Wata Standard.png|thumb|right|200px| [https://www.antenna.ch/en/water-hygiene/guinea/ Antenna-Tinkisso] sells bottles of sodium hypochlorite for water disinfection under the brand name Chlor'C.]]
 +
When sodium hypochlorite is added to water the active chlorine is involved in three separate reactions:
 +
*Active chlorine reacts through oxidation with organic matter and pathogens in the water and kills them. This portion is called consumed chlorine.  
 +
*Some chlorine reacts with other organic matter and forms new chlorine compounds. This portion is called combined chlorine.
 +
*Excess chlorine that is not consumed or combined remains in the water. This portion is called free residual chlorine (FRC). The free residual chlorine helps prevent recontamination of the treated water.
  
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The treated water should be stored in a clean, opaque, closed container. The WATA device, equipment, and containers used should be rinsed thoroughly after every procedure.
+
After the chlorine is added the water should be shaken or stirred thoroughly and left for 30 minutes. After this time, there should be 0.5-1.0 mg/L of free residual chlorine (FRC) left. This is the minimum level of FRC is needed to ensure adequate disinfection. The FRC levels can be measured using the WataBlue reagent.
  
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====Manufacturing====
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Note that the effectiveness of chlorine for disinfecting water depends on the turbidity, the organic matter content, the temperature and the pH of the water being treated. For high turbidity levels (>5 turbidity units), the water should use a filtration or sedimentation technique to remove excess suspended solids before adding chlorine. This is because the suspended solids will consume the active chlorine needed for inactivation of microbes.
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The WATA device is a registered product from Antenna Technologies.  
 
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The WATA kit includes:
 
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* Power supply (12V/ 5A)
 
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* Electric transformer
 
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* 50ml and 5ml syringe
 
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* Spoon to measure salt (± 25g)
 
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* Opaque plastic recipient container (±2.5L)
 
  
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Extra materials needed to produce chlorine concentrate are:
+
The chlorine concentrate produced is not very dangerous; it is less toxic than bleach. In case of skin or eye contact, rinse well with water. Prolonged inhalation of the chlorine fumes could be dangerous. It should be kept away from children. The treated water should be stored in a clean, opaque, closed container. The WATA device, equipment, and containers used should be rinsed thoroughly after every procedure.  
−
* Salt
 
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* Clear, fresh water
 
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* Containers for salt solution and brine, and treated water.  
 
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* Power source (car battery, solar panel, etc.)
 
  
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No particular experts or trained workers are required for production of chlorine concentrate. The device should only be used by adults. The user guide should be carefully read before use.  
+
====Other Applications====
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The chlorination however should be supervised by a qualified person.
+
The chlorine concentrate is suitable for various applications apart from disinfecting water (chlorine refers to sodium hypochlorite at 5 grams of active chlorine per liter):
 +
*Dakin’s solution for disinfecting wounds: No dilution (use full concentration of active chlorine at 5 grams per liter)
 +
*To clean floors, bathrooms or latrines: 1 part chlorine is diluted with 2 parts water. It needs 5 minutes to react, after which it is rinsed with drinking water.  
 +
*To wash hands: 1 part chlorine is diluted with 11 parts water. It needs 5 minutes to react, after which the food should be rinsed with drinking water.  
  
 
====Maintenance====
 
====Maintenance====
−
It is advisable to treat the WATA device after about 150 hours of use. The mini-WATA and regular WATA can be treated by immersing them in a container filled with lemon juice or vinegar for a night. The maxi-WATA needs to be treated with diluted sulphuric acid or hydrochloric acid.  
+
Devices need to be rinsed after each procedure with clean water. If after several uses you notice white marks on the WATA, prepare a mixture of 50% vinegar (or lemon juice) and 50% clean water. For the Mini-WATA and WATA-Standard, leave the device to soak for several hours (overnight for example) and then rinse it with clear water. Never scrub the titanium plates. WATA-Plus and Maxi-WATA need to be soaked for at least 24 hours and be completely immersed in 6-10 liters of the same vinegar & clean water mixture.
  
 
====Estimated Lifespan====
 
====Estimated Lifespan====
−
The WATA device is expected to operate for about 20,000 hours. If used for 12 hours a day, 7 days a week, it would last about 4.5 years.
+
Properly used, well maintained and carefully stored after each use, WATA devices are designed to operate for 10,000 operating hours, or around 5 years of use.
−
 
 
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==Costs==
 
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Excluding shipping, the costs are:
 
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* Mini-WATA kit: 40 euros
 
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* WATA kit: 200 euros
 
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* Maxi-WATA kit: 1700 euros
 
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* WATA blue reagent: free if a WATA kit is bought
 
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* WATATest reagent: free if a WATA kit is bought
 
−
 
 
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After the initial set-up costs, the cost of using a WATA kit has been estimated at 0.01 euros per litre of concentrate, cleaning 4000 litres of water.
 
−
 
 
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==Field Experiences==
 
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The WATAsol has been supplied to partners and is being used in around 50 countries including:
 
−
Angola, Bangladesh, Benin, Burkina Faso, Burundi, Cambodia, Cameroon, Central African Republic, Chile, Congo-Brazzaville, Côte d'Ivoire, [http://www.antenna.ch/en/drinking_water/wata_drc_en.html Democratic Republic of Congo], Djibouti, Ecuador, [http://www.antenna.ch/en/drinking_water/wata_guinea_en.html Guinea Conakry], Haiti, India, Iran, Italy, Kenya, Laos, Madagascar, [http://www.antenna.ch/en/drinking_water/wata_mali_en.html Mali], Mauritania, Mozambique, Myanmar, [http://www.antenna.ch/en/drinking_water/wata_nepal_en.html Nepal], Niger, Reunion, San Salvador, Senegal, Sierra Leone, Sri Lanka, Sudan, Tajikistan, Tanzania, Togo, Uganda, Vietnam and Zimbabwe.
 
−
 
 
−
'''Mali'''<br>
 
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In [http://www.antenna.ch/en/drinking_water/wata_mali_en.html Mali], Antenna Technologies is working with the local NGO Formations Sans Frontieres, on a programme to provide 10 health centres with WATA devices to take care of the hygiene in the centres as well as provide safe drinking water to the community.
 
−
 
 
−
'''Nepal'''<br>
 
−
In [http://www.antenna.ch/en/drinking_water/wata_nepal_en.html Nepal], they launched a project together with the ECCA, Environmental Camps for Conservation Awareness. It will provide WATA kits to schools in poor and rural areas throughout Nepal.  
 
  
−
'''DMC'''<br>
+
====Costs====
−
In the [http://www.antenna.ch/en/drinking_water/wata_drc_en.html Democratic Republic of Congo], Antenna supports a women-led programme which provides education and WATA kits to individual households, to ensure safe water on a household level and reduce common waterborne diseases such as cholera.
+
Visit the Watatechnology.com webshop for the pricing of the WATA range of devices: [https://watatechnology.com/en/order/]
  
−
==Reference manuals, videos, and links==
+
====Field Experiences====
−
* [http://www.antenna.ch/en/drinking_water/wata-products.html WATA kit manuals, provided by Antenna Technologies.]
+
[[Image:WATA device in Spring Health.png|thumb|200px| The WATA-Standard  is the source of chlorine used to disinfect the drinking water [http://www.paulpolak.com/_slide/spring-heath/ Spring Health] delivers to rural households in Odisha, India.]]
−
* [http://www.antenna.ch/en/drinking_water/wata-quality.html Quality control reagent manuals, provided by Antenna Technologies.]
+
The  WATA range of devices is being used in over 100 countries including: Angola, Bangladesh, Benin, Burkina Faso, Burundi, Cambodia, Cameroon, Central African Republic, Chile, Congo-Brazzaville, Côte d'Ivoire, Democratic Republic of Congo, Djibouti, Ecuador, Guinea Conakry, Haiti, India, Iran, Italy, Kenya, Laos, Madagascar, Mali, Mauritania, Mozambique, Myanmar, Nepal, Niger, Reunion, San Salvador, Senegal, Sierra Leone, Sri Lanka, Sudan, Tajikistan, Tanzania, Togo, Uganda, Vietnam and Zimbabwe.
−
* [http://www.antenna.ch/en/drinking_water/wata-description.html Description of the WATA device on the website of Antenna Technologies.]
+
*'''Guinea:''' Tinkisso-Antenna sells 250 mL flaks of sodium hypochlorite solution produced with WATA devices across the country. More information on Tinkisso-Antenna’s work here: [https://www.antenna.ch/en/water-hygiene/guinea/]
−
* [[Solution_of_the_week_3|Akvo water solution of the week 3.]]
+
*'''India:'''  Antenna Foundation has two partners in India using two different business models to bring chlorine to rural households. Spring Health delivers drinking water to rural households that has been chlorinated with sodium hypochlorite produced using the WATA device. TARA produces sodium hypochlorite, bottles it and then uses a network of micro franchisors and partners to reach the end consumer in rural households. More information on Antenna Foundation’s work with Spring Health and TARA available here: [https://www.antenna.ch/en/activities/water-hygiene/india/]
  
−
==Acknowledgements==
+
====Further Reading====
 +
* WATA devices and reagents tutorial videos : [https://www.youtube.com/playlist?list=PLLCDBpdIkWj1W4UtNrMnV5Eiblhl1eslm]
 +
* Short video on the WATA device produced by Antenna Foundation for World Water Day 2017: [https://www.youtube.com/watch?v=nNTr8wJqooM]
 +
* Antenna Foundation’s Water & Hygiene department: [https://www.antenna.ch/en/water-hygiene/]
 +
* Frequently Asked Questions (FAQ) about the WATA range of devices: [https://watatechnology.com/fr/faq/]

Latest revision as of 15:49, 25 October 2022

English Français Español भारत മലയാളം தமிழ் Swahili 한국어 中國 Indonesia Japanese
Tinkisso-Antenna employees in Guinea holding Maxi-WATA devices.

The WATA device makes use of the simple process of electrolysis (electrochlorination) to produce sodium hypochlorite at a concentration of 5 grams per liter using only salt and water as inputs. As the active chlorine has a strong oxidizing power, it effectively inactivates the vast majority of disease-causing bacteria and viruses.

Chlorine began to be widely used as a disinfectant in the early 1900’s. It revolutionized drinking water treatment and dramatically reduced the incidence of waterborne diseases. In many countries, including the United States, chlorine remains the most widely used chemical for water disinfection.

Sodium hypochlorite is one form of chlorine used for water disinfection. It can be manufactured in remote locations since it can be obtained through the electrolysis of salt water. In bottles of sodium hypochlorite in a wide range of sizes can be purchased from a variety of vendors in countries around the world. Chlorine concentrations range from 0.5 to 10% and each product has its own instructions for correct dosing of contaminated water. One common product containing sodium hypochlorite is liquid household bleach.

The problem is that in many developing countries chlorine is imported rather than produced locally. This steeply increased the price of chlorine for the user as it adds transportation, storage, and other related costs. In addition, the quality of the sodium hypochlorite, like with many other products, degrades in quality over the course of improper handling and storage over the course of long transportation times. The WATA range devices, developed by Antenna Foundation, allows chlorine to be produced locally to provide chlorine disinfectants for individual households, health centres and hospitals, and emergency relief.

Active chlorine solution is being produced using the WATA range of devices in over 100 countries. It reaches people in need through local NGOs and community groups, international organizations, municipal authorities and private enterprises. Since the WATA range of devices was first launched in 2009, Antenna Foundation is hoping to expand their reach further through partnerships, especially with local enterprises. The WATA devices have also been incorporated into development programmes led by other organizations.

Advantages Disadvantages
- Local production (avoids most storage and transportation problems and environment impacts.

- Generation of income for local communities as the local production also creates employment and local development opportunities.
- Solar versions available for autonomous use.
- Quality control is possible at every stage of production and use.
- Low cost
- Especially suitable for humanitarian response or where armed conflict has led to an embargo on chlorine gas and powder.
- Easy to use.
- Can be used as a disinfectant for a large range of applications (e.g. disinfecting laboratory equipment, wounds, cleaning latrines, disinfecting kitchen utensils and surfaces, washing rough fruits and vegetables etc.).

 - Electricity required (but can be run with solar energy)

- Education and training for operators are essentials, especially when using Maxi- WATA.
- Chlorination can cause the generation of a very low concentration of toxic disinfection by-products (DBPs) in the case of disinfecting water with a high organic matter content.
- Dosage might more difficult than with tablets
- Only clear water can be used to produce WATA solution and the solution is only effective in treating clear water
- The device should only be used by a responsible person familiar with the user manual for the relevant WATA device.
- Requires wating 30 minutes after treatment before the water is ready for consumption.
- Chlorine taste and smell


The WATA Range of Devices

The range of WATA devices and reagents

The device comes in four models for different scales of chlorine production: Mini-WATA (0.5L of solution), WATA-Standard (2L of solution), WATA-Plus (15L of solution) and Maxi-WATA (60L of solution). The Mini-WATA, the WATA-Standard and the WATA-Plus are all capable of running off of a solar energy source allowing them to be deployed in regions that lack stable access to electricity. The devices take 2 hours to convert the brine solution to active chlorine solution. Once the process is finished, one litre of that solution is good for disinfecting 5,000 litres of water.

Operation
Instructions to create the salt water solution to be transformed into sodium hypochlorite. Taken from the WATA manual

The device should only be used by adults. The user guide should be carefully read before use. The chlorination however should be supervised by a qualified person.

The only input needed for the production of sodium hypochlorite at 5 grams per liter is salt water at a concentration of 25 grams per liter. To arrive at this concentration, first prepare a brine and then mix 1 unit of brine for 3 units of clear water for the required amount of salt water. The amount of salt water needed for production varies by device.

To prepare the brine, a (non-metallic) container is filled with clear water. A large amount of salt is added (about 400g per liter of water) and the mixture is shaken for half an hour till as much salt as possible is dissolved. To make sure the solution is saturated, there should be some salt remaining at the bottom of the container. If no excess salt is visible, more is added till the solution is saturated. It can be stored for up to six months and can then be mixed with fresh water for production. The water used to prepare the brine solution also needs to be clear as high turbidity levels will interfere with the electrolysis process.

Once the salt solution is ready, the WATA device should be totally immersed in the solution. Connect the WATA device to the power supply and turn on the machine. The amount of time it takes to The power supply of the WATA device (of 110V or 220V) is plugged in. The device works on 12 V direct current. It can be plugged directly into a car battery, car battery charger or solar panel. A grid or diesel generator delivering alternating current can also be used with the provided transformer.

Active chlorine is very sensitive to light and degrades relatively quickly if not stabilized for long term storage. The stabilization process involves raising the pH of the chlorine solution and will allow it to be stored up to 3 months. It can be achieved with the WataStab reagent kit. If not stabilizing the solution should be used with 24 hours if disinfecting drinking water. It can be stored for longer if destined for cleaning purposes, although the concentration will deteriorate over time and it should be measured before use to ensure an adequate level of disinfection.

Use for Water Disinfection

Antenna-Tinkisso sells bottles of sodium hypochlorite for water disinfection under the brand name Chlor'C.

When sodium hypochlorite is added to water the active chlorine is involved in three separate reactions:

  • Active chlorine reacts through oxidation with organic matter and pathogens in the water and kills them. This portion is called consumed chlorine.
  • Some chlorine reacts with other organic matter and forms new chlorine compounds. This portion is called combined chlorine.
  • Excess chlorine that is not consumed or combined remains in the water. This portion is called free residual chlorine (FRC). The free residual chlorine helps prevent recontamination of the treated water.

After the chlorine is added the water should be shaken or stirred thoroughly and left for 30 minutes. After this time, there should be 0.5-1.0 mg/L of free residual chlorine (FRC) left. This is the minimum level of FRC is needed to ensure adequate disinfection. The FRC levels can be measured using the WataBlue reagent.

Note that the effectiveness of chlorine for disinfecting water depends on the turbidity, the organic matter content, the temperature and the pH of the water being treated. For high turbidity levels (>5 turbidity units), the water should use a filtration or sedimentation technique to remove excess suspended solids before adding chlorine. This is because the suspended solids will consume the active chlorine needed for inactivation of microbes.

The chlorine concentrate produced is not very dangerous; it is less toxic than bleach. In case of skin or eye contact, rinse well with water. Prolonged inhalation of the chlorine fumes could be dangerous. It should be kept away from children. The treated water should be stored in a clean, opaque, closed container. The WATA device, equipment, and containers used should be rinsed thoroughly after every procedure.

Other Applications

The chlorine concentrate is suitable for various applications apart from disinfecting water (chlorine refers to sodium hypochlorite at 5 grams of active chlorine per liter):

  • Dakin’s solution for disinfecting wounds: No dilution (use full concentration of active chlorine at 5 grams per liter)
  • To clean floors, bathrooms or latrines: 1 part chlorine is diluted with 2 parts water. It needs 5 minutes to react, after which it is rinsed with drinking water.
  • To wash hands: 1 part chlorine is diluted with 11 parts water. It needs 5 minutes to react, after which the food should be rinsed with drinking water.

Maintenance

Devices need to be rinsed after each procedure with clean water. If after several uses you notice white marks on the WATA, prepare a mixture of 50% vinegar (or lemon juice) and 50% clean water. For the Mini-WATA and WATA-Standard, leave the device to soak for several hours (overnight for example) and then rinse it with clear water. Never scrub the titanium plates. WATA-Plus and Maxi-WATA need to be soaked for at least 24 hours and be completely immersed in 6-10 liters of the same vinegar & clean water mixture.

Estimated Lifespan

Properly used, well maintained and carefully stored after each use, WATA devices are designed to operate for 10,000 operating hours, or around 5 years of use.

Costs

Visit the Watatechnology.com webshop for the pricing of the WATA range of devices: [1]

Field Experiences

The WATA-Standard is the source of chlorine used to disinfect the drinking water Spring Health delivers to rural households in Odisha, India.

The WATA range of devices is being used in over 100 countries including: Angola, Bangladesh, Benin, Burkina Faso, Burundi, Cambodia, Cameroon, Central African Republic, Chile, Congo-Brazzaville, Côte d'Ivoire, Democratic Republic of Congo, Djibouti, Ecuador, Guinea Conakry, Haiti, India, Iran, Italy, Kenya, Laos, Madagascar, Mali, Mauritania, Mozambique, Myanmar, Nepal, Niger, Reunion, San Salvador, Senegal, Sierra Leone, Sri Lanka, Sudan, Tajikistan, Tanzania, Togo, Uganda, Vietnam and Zimbabwe.

  • Guinea: Tinkisso-Antenna sells 250 mL flaks of sodium hypochlorite solution produced with WATA devices across the country. More information on Tinkisso-Antenna’s work here: [2]
  • India: Antenna Foundation has two partners in India using two different business models to bring chlorine to rural households. Spring Health delivers drinking water to rural households that has been chlorinated with sodium hypochlorite produced using the WATA device. TARA produces sodium hypochlorite, bottles it and then uses a network of micro franchisors and partners to reach the end consumer in rural households. More information on Antenna Foundation’s work with Spring Health and TARA available here: [3]

Further Reading

  • WATA devices and reagents tutorial videos : [4]
  • Short video on the WATA device produced by Antenna Foundation for World Water Day 2017: [5]
  • Antenna Foundation’s Water & Hygiene department: [6]
  • Frequently Asked Questions (FAQ) about the WATA range of devices: [7]
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