Purifying sea water as easy as cooking rice

My Favorite Challenge 

One thing which has made me curious since childhood is that there is so much of water around us, still we face shortage of potable water day in and day out. Water crisis is present in almost all parts of world, irrespective of whether it is a developed, developing or an underdeveloped nation.

 

The snippet below shows that only 3% of earth water is freshwater while 97% is saline ocean water. Of this 3% fresh water approx. 68.7% is in form of glacier and rest in form of ground & surface water. Water is a basic element for life on earth. Humans have been primarily responsible on not utilizing the available fresh water prudently. They have been main source to wastage and contamination of the fresh water available on surface or underground. 

Governments across the globe have become aware of this situation and are taking reasonable steps to conserve these water resources. All these initiatives can help delay major water crisis but not stop it. Hence my challenge is how can we make sea water (saline water) economically available and fit for human consumption. The challenge is to develop way and means to process / filter or treat sea water so that it can be used for domestic consumption, which is economically viable. One metaphor which corresponds to this situation is “Purifying sea water as easy as cooking rice”.

Now the reason why it is very important to me is because I am native of Jaipur, Rajasthan, India. Jaipur is capital of Rajasthan, which is the desert state in India. The great Indian Thar Desert forms a major part of the state. Being a desert state it has been always been in shortage of water. In my childhood, I have lived across 3 cities in Rajasthan (Jaipur, Jodhpur and Ajmer) and travelled to many others. I have seen days when we used to get government supply of water once in 3 to 4 days and had to rely on water tankers many a times to satisfy our domestic needs. The natural scarcity of water in the state made it not only prudent in utilizing its resources but also securing its future. Still there is water crisis in some parts of Rajasthan but a lot of progress and improvement has been made over last years to ensure the same. Southern parts of India which receive adequate rainfall and are rich with water bodies are now facing water crisis because of absence of this prudence in using water resources. I had never imagined that cities like Chennai, Bangalore will ever face such kind of crisis, which receive good rainfall and have so many surface water bodies. The past situation which I had faced in Rajasthan has become present situation for these cities. Another reason is increasing population and thus consumption in these mega cities.

Rising water demands associated with population growth, increased water consumption per capita and economic growth, coupled with diminishing water supplies due to climate change and contamination, are exacerbating water scarcity in most world regions. Recent estimates suggest that 40% of the global population faces severe water scarcity, rising to 60% by 2025. Furthermore, 66% of the global population (4 billion) currently lives in conditions of severe water scarcity for at least one month per year. These statistics demonstrate that “conventional” sources of water such as rainfall, snowmelt and river runoff captured in lakes, rivers, and aquifers are no longer sufficient to meet human demands in water-scarce areas. This is also in direct conflict with Sustainable Development Goal (SDG) 6, aimed at ensuring the availability of clean water for current and future generations.

Water-scarce countries and communities need a radical re-think of water resource planning and management that includes the creative exploitation of a growing set of viable but unconventional water resources for sector water uses, livelihoods, ecosystems, climate change adaptation, and sustainable development. Whilst water demand mitigation approaches such as water conservation and improved efficiencies can somewhat close the water demand and supply gap, these approaches must be combined with supply enhancement strategies in order to combat water scarcity. Such water resources conservation and supply enhancement strategies are already practiced in some water-scarce areas. However, expansion is required, particularly in areas where water scarcity and water quality deterioration is intensifying

We can still try to reverse the situation but an interim solution in required to tide over current water crisis. Hence my challenge is how we can treat ocean water such that it is available for human consumption and is economically viable. In order to find solutions we need to look at parts of world which already are ahead in this field. There are countries like Israel which uses sea water and desalinates it to satisfy 40% of its water demands. Other places like California, Middle East etc are also heavily dependent on desalinated sea water. This is just one part of the problem that is making alternate source of water available for domestic consumption. Other part is prudent usage of existing resources and securing future. In order to look for solutions for such issues we can look at practices of states like Rajasthan which have been partially successful in taking steps towards the same.

Seawater desalination technology, available for decades, made great strides in many arid areas of the world such as the Middle East, the Mediterranean, Australia and the Caribbean. Desalination plants operate in more than 120 countries in the world, including Saudi Arabia, Oman, United Arab Emirates, Spain, Cyprus, Malta, Gibraltar, Cape Verde, Portugal, Greece, Italy, India, China, Japan, and Australia. There are 15,906 operational desalination plants producing around 95 million m3/day of desalinated water for human use, of which 48% is produced in the Middle East and North Africa region.

Thus we can see that this is one of the most common crisis faced by most of the world population and there is progress in field of desalination of ocean water to tide over this crisis. There are various ways and locations where we can learn the ways by which this crisis can be tackled.

 

How can we treat sea water (saline) at low / affordable cost and make it fit for human consumption?

For this I have created a story-board to highlight problem and one probable solution

 

To test a proposed solution I have also created a looks-like prototype (sketch) to show how the prototype is going to look.

1 Day Experiment

I’ll take a black tray 2ft x 1.5 ft and cover it with slightly larger transparent plastic sheet (as shown in the diagram). On the sides I’ll place empty trays to collect pure water and then place the tray under sun for 1 day and at end will measure the amount of pure water collected after condensation in external trays. This experiment will test whether energy from sun can be directly used for water desalination, which will be economical as well as consuming lesser renewable energy.

Cost of this experiment will be approximately INR 1000-1500. Amount of water collected in this experiment will be a measure of success of this experiment. If 5-7 liters of water can be collected then I think it can be termed as a successful experiment.