Can coastal Bangladesh turn salty wastewater into a new industry?

Every morning across coastal Bangladesh, thousands of people collect drinking water from reverse osmosis (RO) plants because the ponds and tube wells that once sustained their communities have become too saline to drink. 

In districts such as Satkhira, Khulna, Bagerhat and parts of Cox's Bazar, these desalination plants—installed by government agencies, NGOs and private operators—have become a lifeline as rising salinity, driven by climate change, tidal surges and sea-level rise, continues to contaminate freshwater sources.

Yet every glass of clean water tells only half the story.

RO technology works by separating freshwater from dissolved salts. Typically, only about half of the feedwater becomes drinking water, while the remainder emerges as a highly concentrated saline stream known as 'Brine'. In many coastal communities, this reject water is discharged into drains, canals, ponds or nearby land with little thought given to its long-term environmental impact. In some places, shrimp hatcheries reportedly purchase this saline wastewater because of its high salt concentration. However, without proper testing and regulation, such practices raise legitimate questions about water quality and environmental safety.

It is ironic in climate adaptation that Bangladesh invests considerable effort in producing freshwater for its coastal communities, but pays far less attention to what happens to the leftover water.

As climate change intensifies, the demand for desalinated drinking water will only grow. More RO plants will inevitably produce more brine. Instead of treating this by-product as an unavoidable waste, Bangladesh should ask a different question: could this concentrated saline stream become the foundation of a new climate-tech industry?

Around the world, that question is already attracting serious attention. Researchers and industries increasingly speak of "brine valorisation"—recovering additional freshwater, industrial salts, and valuable minerals from desalination waste instead of simply disposing of it. 

In countries such as Saudi Arabia and the Arab Emirates, where desalination is central to daily life, governments and companies are investing in technologies that treat brine as a resource rather than a liability. In India, Zero Liquid Discharge systems are helping industries such as textiles and power generation recover water while minimising wastewater.

Bangladesh's circumstances are different. Our coastal desalination plants are much smaller than the giant facilities of the Gulf, and their economics will not be the same. Nor does this mean we should immediately start producing table salt from RO waste. The chemical composition of brine varies depending on the source water and may contain impurities that make it unsuitable for food use. 

Nevertheless, opportunities may exist to recover additional freshwater, produce industrial-grade salts, or extract other useful materials where technically feasible and commercially viable. The objective should not be to manufacture another product at any cost, but to recover resources that are currently being lost.

This possibility deserves attention because coastal Bangladesh already possesses something many countries would have to build from scratch: a growing network of community-based desalination plants located precisely where salinity is most severe. Unlike household RO systems, whose reject water is scattered across thousands of homes, community plants generate concentrated brine at a single location. That makes them practical sites for testing resource recovery technologies.

Imagine a community desalinatiin plant in Shyamnagar or Dacope that not only supplies safe drinking water but also uses advanced treatment to recover additional freshwater, then safely manages or reuses the remaining brine. If such systems prove technically and financially viable, they could improve water efficiency, reduce disposal challenges, and create new business opportunities in water treatment, environmental engineering and resource recovery. 

Communities would benefit from improved water management, while local entrepreneurs and technology companies could develop services tailored to the unique conditions of coastal Bangladesh.

Turning that vision into reality will require more than good intentions. Bangladesh needs a coordinated innovation programme that brings together the Department of Public Health Engineering, universities, research institutions, NGOs, private desalination operators, technology start-ups and industries experienced in advanced water treatment. 

Rather than launching large-scale projects immediately, the government should establish competitive pilot programmes in districts like Satkhira, Khulna and Bagerhat to test different approaches under real-world operating conditions. The goal should be simple: determine whether resource recovery from community RO plants can deliver environmental and economic value.

Not every pilot will succeed. Some technologies may prove too expensive. Others may recover too little value to justify investment. But this is how innovation works. Bangladesh did not become a global leader in microfinance, ready-made garments or mobile financial services by waiting for certainty. Those successes emerged through experimentation, adaptation, and persistence.

Climate change is forcing Bangladesh to rethink how it secures freshwater for its coastal communities. It should also prompt us to rethink what we call waste. The brine flowing out of community desalination plants may never become a goldmine, and not every recovery technology will make economic sense. But assuming that this increasingly abundant resource has no value simply because we have always discarded it would be a costly mistake.

For decades, Bangladesh has focused on bringing freshwater to its salty coast. The next challenge is deciding what to do with what remains. If even a handful of pilot projects can recover more water, reduce waste, and unlock new economic opportunities, they could lay the foundation for a distinctly Bangladeshi climate-tech industry—one built not by discovering a new natural resource, but by reimagining an overlooked by-product of climate adaptation.

Shafiq R Bhuiyan is a storyteller who examines the intersection of social progress, effective communication, cultural development, and corporate social responsibility while sharing insights to inspire change. 

Disclaimer: The views and opinions expressed in this article are those of the authors and do not necessarily reflect the opinions and views of The Business Standard.