Self-powered water purification

The dairy sector is one of the most environmentally unfriendly industries, producing large amounts of effluent containing hard-to-remove inorganic and organic compounds. Wastewater can be treated electrochemically to remove fats, oils and milk solids that are resistant to conventional chemical or biological treatment, but this option is energy intensive.

In response, the EU-funded REWAGEN (Electrochemical water treatment system in the dairy industry with hydrogen recovery and electricity production) project is developing a self-sustaining wastewater treatment plant. It will use hydrogen generated during electrochemical treatment to power the system.

In REWAGEN's prototype system, fats and oils are first separated from wastewater using electricity that coalesces oil droplets at the oil-water interface. Next, two electrochemical treatment steps cause suspended solids to coagulate or clump, and organic materials to precipitate, aiding their removal from water.

The hydrogen by-product of this electrochemical treatment is then recovered, purified and stored in a fuel cell to be used as a secondary power generator. Finally, completing the entire cycle, water generated as a waste product of the hydrogen fuel cell is recycled for various uses.

REWAGEN has so far developed lab-scale electrochemical technologies capable of removing fats, oils and up to 98 % of solids from wastewater. Researchers have also created a process to collect and purify hydrogen gas, and are exploring ways to reuse organic solids for energy generation or fertilisers.

When scaled up for the dairy industry, this efficient wastewater treatment process should lower costs by reducing energy and water consumption. In addition, REWAGEN's innovative method for converting electrochemically generated hydrogen into energy could benefit the fuel cell industry.