Industry’s first integrated water-treatment system tailored for green hydrogen – Chemical Engineering

January 10, 2025 | By Mary Page Bailey

The decarbonization potential of “green” hydrogen produced through water electrolysis using renewable energy is promising. Numerous research activities around the world aim to improve the efficiency and cost of electrolysis by exploring new catalysts, membranes and more. However, less attention is paid to a primary input for electrolytic cells – water. In this interview, Prakash Govindan, co-founder and chief operating officer of Gradiant Corp. (Boston, Mass.), the company's integrated approach to water treatment and how expanding green hydrogen production through water electrolysis is changing the way water treatment technologies are used.

Gradiant's green hydrogen water treatment platform (Source: Gradiant)

Gradiant's water treatment solution, called ProtiumSource, is said to be the industry's first electrolyzable water solution that works with any water source, including seawater, brackish water or even treated wastewater. “ProtiumSource combines advanced water treatment technologies in an integrated three-phase system tailored for green hydrogen producers. No other solution on the market integrates all three aspects of spring water production through electrolyzers: water purification; highly pure water for electrolysis; and brine management for liquid-free discharge [ZLD]says Govindan.

In the pretreatment and water purification phase (Step 1), reverse osmosis (RO) technology and selective pollutant extraction technologies efficiently remove a full range of inorganic and organic pollutants from the feed water, such as: B. Fluoride, potassium, iron and more. During the high purity water production phase (Step 2), large flow volumes are polished to produce water that exceeds industry standards for use in electrolyzers. This step is capable of obtaining ultrapure water with parts per trillion purity through a combination of ion exchange, electrodeionization and ultraviolet technologies.

Finally, ProtiumSource integrates integrated brine management for ZLD, which, unlike other systems, ensures that the wastewater from the production of high-purity water (step 3) is treated to the extent that no liquid waste is released into the environment. This step uses Gradiant's patented Counterflow Reverse Osmosis (CFRO) technology.

Brine management is a key element that enables the use of such a wide range of water sources. “The company’s ZLD solution recovers up to 100% of final brine concentrations and pushes the limits of salt saturation to minimize or eliminate liquid waste, leaving only solids for disposal or meaningful reuse. This is particularly important for green hydrogen production sites, where efficient water waste management is critical to business continuity. There is no liquid waste released into the environment,” adds Govindan. This step concentrates the wastewater, leaving only salts, minerals and other contaminants removed from the feedwater as the final byproducts. The technology maximizes water recovery and leaves concentrated solids that are easier to handle, eliminating the need for wastewater disposal and minimizing the environmental impact of green hydrogen production.

The system is said to operate with 40% less energy and deliver 60% cost savings compared to traditional technologies, while also accommodating a wide range of feedwater and operating conditions due to lower equipment costs and minimized system downtime. Additionally, says Govindan, CFRO technology significantly increases the water recovery rate up to 99%, compared to 75% for traditional RO systems, drastically reducing wastewater disposal needs. “This makes Gradiant’s CFRO a critical and differentiated solution for green hydrogen producers facing stringent water management and environmental requirements,” he notes.