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Wednesday, April 5, 2023

How desalination plants contribute to global warming and solutions to address them?

How desalination plants contribute to global warming and solutions to address them? I posted the following article in my blog in 2014. We are now addressing this problem by setting one the largest integrated membrane-based sea water desalination plants in India using renewable power without using oil and gas. Highly contaminated and concentrated effluent discharge from existing and operating desalination plants around the world have greatly contributed to global warming according to world’s leading research institutions in marine science and oceanography. The ocean’s circulation which acts as conveyor belt distributes the increasing salinity and temperature of the sea across the globe. Several companies are researching on solutions to address the above problem and to achieve a Zero Liquid Discharge (ZLD) concept. Concepts such as FO (forward osmosis), OARO (osmosis assisted RO), NF pre-treatment with EDR, recovery of minerals such as Potassium chloride, Magnesium chloride (a precursor for extraction of Magnesium metal), Lithium chloride, Bromine etc. Theoretically all these solutions are encouraging but when to come to practise there are several hurdles to get over. Currently the most popular SWRO process is to recover 40% fresh water from seawater and discharge the balance 60% with twice its salinity and contaminated chemical are discharged in the sea. Such practice is going on since sixties when RO membranes were introduced. SWRO is an energy intensive process along with thermal evaporation they contribute to a great amount of green house gases. Despite several improvements in energy conservation in membrane processes the emissions of GHG was never addressed till date. Meanwhile several large-scale desalination plants are planned and implemented to overcome severe shortage of fresh water especially in African countries and pacific island and many arid regions of the world. We in CEWT are introducing CAPZ (clean water at affordable price with zero discharge) desalination a proprietary technology that not only achieve the highest recovery of fresh water from sea water but also generates simultaneously a highly value added ultrapure saturated Sodium chloride brine that serves as feed stock for chloralkaline industries substituting ‘solar evaporated salt’ as a source of Sodium. The pure saturated Sodium chloride brine is the feedstock to produce Caustic soda using membrane electrolysis as well as to produce Soda ash using Solvay process. Modern chloralkaline plants are very large in scales of operation which requires large quantities of solar salts. Due to climate change and unseasonal monsoon rains that have severely affected the solar salt production world-wide leaving a large gap between demand and supply. It has sharply increased the price of solar salt in the international market. Bulk of the solar salt is also used in ‘de-icing’ road due to severe snow in the industrialised countries. CAPZ desalination can recover up to 72% fresh water as well as 4.70% saturated sodium chloride brine simultaneously. Directly from seawater. Our current proposed plant in India will produce about 10,000 Mt of saturated Sodium chloride brine per day or 3150 Mt/day of high-quality salt along with 80,000 m3/day of fresh water from a seawater intake of 182,000 m3/day achieving zero liquid discharge (ZLD). We can also retrofit OARO system in our process to further increase water and salt production making it the most effective and economical and environmentally desalination technology in the world!

Wednesday, November 2, 2022

CAPZ desalination , salt production and chemical industries. Climate change will change the future of salt industries in India and elsewhere due to unseasonal monsoon rains, flooding, increasing humidity, harsh working conditions for the labour, low and unsustainable wages, increasing demand for salt world wide for de-icing of roads. The price of salt in India is as low as Rs1200/Mt ($15/Mt) but the price of salt in the international market is as much as $170/Mt. Chemical manufacturers consume almost 80% of salt produced in India but they have to use elaborate purification process in order to use them in the production of Caustic soda and soda ash. When purifying solar evaporated salt and converting to into a purified 315 gpl concentration Sodium chloride brine their cost increases substantially to as much as $ 150/Mt. The increase in cost is about 10 times the cost of raw salt. Solar salt requires a large area of land, dry weather, low humidity and strong wind and long residence time, about 8-10 months. With increasing production of Chemicals, the usage of salt has increased substantially. It has created a huge supply demand gap increasing the price of salt. But the wages of labour remain the same in spite of harsh weather conditions, exploitation of women labour have created many social issues. We in CEWT are working hard to bring about a change by introducing our CAPZ desalination technology. CAPZ desalination technology generates purified 315 gpl concentrated Sodium chloride brine directly from sea water and also generate substantial amount of fresh drinking water. The future water demand world wide requires a substantial recovery of fresh water from seawater not just 40% . CAPZ is the only desalination technology in the world that separates salt in the form of readily usable brine and drinking water simultaneously making it an important and critical technology for drinking water as well as salt and Chemical industries in the future. It offers stability to the price of salt and chemicals derived from them. For example, critical metals like Aluminium which depends on the availability of Caustic soda cannot fix their price because of uncertainty and fluctuating price of salt and Caustic soda. Chemical industries are one of the most polluting industries in the world that generates hundreds of thousand of solid toxic wastes all over the world and such wastes are invariably dumped into the sea severely damaging the marine life and creating ecological problems. It is time Chemical industries adopt CAPZ desalination technology for a sustainable future! Thanks "The Hindu " for the following you tube video that highlights the problems faced by salt industry in India. How climate change is making salt farming unsustainable How climate change is making salt farming unsustainable likecelebrate 6