This water treatment startup is already a unicorn, and has $225 million in VC funding

While it might seem like humans and animals consume most of the world's water, heavy industry uses up to half of it. That's why business sectors are looking for new ways to recycle water, especially in the face of increased drought.

Some of the world's most essential industries, like pharmaceuticals, food and beverage, textiles, mining, renewables and power all use huge amounts of water. Now, new companies are finding ways to reclaim and recycle water as inexpensively as possible.

The global water and wastewater treatment market is expected to reach half a trillion dollars by the end of this decade, according to Statista. Much of it now involves harsh chemicals and uses a lot of energy, but companies like Xylem, Veolia and Boston-based startup Gradiant are trying to reduce both costs and energy while eliminating chemicals.

"We take highly contaminated wastewater which contains solvents, which contains dissolved salt, which contains organics, and we eliminate the entire liquid waste," said Prakash Govindan, co-founder and chief technology officer at Gradiant.

Anurag Bajpayee and Govindan founded Gradiant in 2013 as a spinout from the Massachusetts Institute of Technology (MIT)

Gradiant's technology mimics how nature creates rain. Wastewater is heated and pumped into a humidifier and mixed with ambient air. As the two interact, they are heated into vapor, leaving the contaminants behind. Using a proprietary technology, the vapor is transferred to a column with cool clean water. When the two mix, the air cools and drops fresh water, like rain falls from a cloud. The process, according to Gradiant, cuts traditional costs in half.

"Other technologies can recover maybe 50 to 60% of water, but we can recover 99% of water," Govindan said.

Gradiant is the first water purification unicorn. Its client roster is impressive, working with companies that include Coca-Cola, BMW, Pfizer and Adnoc. It claims to save 1.7 billion gallons of water daily, or the amount consumed by 48 million people. It closed over $500 million in new orders in the first half of this year, according to the company, making its growth trajectory attractive to investors.

"Scaling these technologies is difficult. It's easy to find a product, but it's it's much more difficult to find a full end-to-end solution for customers, and that's what Gradiant has done," said Mark Danchak, co-founder at General Innovation Capital Partners, a Gradiant investor.

Gradiant is also backed by Warburg Pincus, M&G Investments, Formation 8, Clearvision Ventures and GRC. It has raised $228 million to date.

CNBC producer Lisa Rizzolo contributed to this piece.