Wata, a simple solution for disinfection and water treatment

Some 783 million people have no access to improved drinking water sources. According to the WHO, “the lack of access to safe drinking water, combined with inadequate sanitation and poor hygiene, is an important contributing factor to the 1.8 million annual deaths from diarrhoeal diseases”.

Injecting active chlorine into drinking water eliminates the pathogenic microorganisms and guards against possible recontamination. Unfortunately, chlorine supply chains do not always reach communities in developing countries, especially communities in rural areas. Where we are looking at water quality rather than quantity, producing chlorine locally is therefore a simple, cost-effective and sustainable means of improving access to drinking water.

Wata is our solution

WATA technology allows the local production of sodium hypochlorite for water treatment and disinfection purposes. It targets communities that lack access to a chlorine supply chain or to a drinkable water supply.

Our Research and Development Department is working with our partners in Switzerland and overseas on improving the WATA technique to meet needs in the field more effectively.

Just take water, salt, electricity… and proper care

A WATA device is a simple tool to produce chlorine. It requires water, salt and electricity. WATA is simply using a well-known technique that has been applied to producing chlorine for almost 200 years. The conductivity of the saline solution increases with the concentration of salt, and this affects the passage of electricity through it. When this limit is reached, the solution is known as ‘saturated’. If you add extra grains of salt, they will not dissolve – they will remain at the bottom of the recipient. In this case, you remove them with a filter. You immerse the WATA device in a saline solution of water with salt (25 grams per litre) and connect it to a reliable source of electricity, and a process of electrolysis takes place.

The electrolysis converts the saline solution (sodium chloride) into active chlorine (sodium hypochlorite). The word ‘electrolysis’ means to dissolve something, or break it up into parts, by passing electricity through it. In our case, the electrolysis breaks up the elements of water and salt, and the result is chlorine. WATA’s special feature is in the design of the device. It is simple and safe to hold, manipulate and use. It operates with small (or large, as desired) volumes of water and salt, and requires simple containers for its liquids.

Water

You must have clear water, both for the process of electrolysis and the water which will be treated with the resulting active chlorine solution. Chlorination cannot be guaranteed if the water is cloudy or muddy. In these cases, the water must be filtered first, or the sediment allowed to settle or flocculate.

Salt

WATA devices can only guarantee their production rate of active chlorine if the initial salt concentration in the water is precisely 25 grams per litre. With small volumes to electrolyse, there is a risk of over-dosage, or under-dosage, of salt because of the precision you need to measure the salt. If you do not have access to good-quality salt and cannot make sure that you pour exactly 25 grams per litre, we highly recommend the use of saturated brine to prepare your salt solution, as follows.

Preparation of saturated brine

Saturated brine is a solution into which the largest possible amount of salt has been dissolved. Water has a salt ‘dissolution capacity’ of 360 grams/litre. This is relatively constant, regardless of the temperature. This means that when you try to dissolve very large quantities of salt in a given volume of water in a recipient (container), only the amount corresponding to the dissolution capacity is actually dissolved. The limit is 360 grams in one litre, 720 grams in two litres and so on. In our ‘recipes’ in user guides, we suggest, for practical reasons, using 400 grams of salt, to be sure of achieving complete saturation.

If you are using the saturated brine method for electrolysis with WATA, the volume of brine must represent 1/13th of the total volume for electrolysis. You must add 80 ml of saturated brine per litre of water.

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