Twence Gives Internal Water Flows a Second Life

Key Takeaways

• Twence has mapped its entire water system, from intake through use to discharge, yielding concrete savings.
• Water flows long handled separately are now assessed together. Water is a permanent agenda item.
• Quick, low-cost steps: the treatment plant takes more water at peaks. clean and dirty composting flows are separated.
• Relatively clean wastewater from the new CO2 capture plant now feeds flue gas cleaning.
• Membrane bioreactor and nanofiltration are under review. Circular water use is the 2030 goal.

Twence has mapped its entire water system and is reusing internal water flows. Circular water use is the goal for 2030.

Twence has mapped its entire water system and is reusing water flows that were previously handled separately. The first measures have already led to concrete savings. The long-term goal is circular water use by 2030.

“For a long time, water was taken for granted, including by us,” says Harry Hegeman, project leader at Twence. “Due to increasing scarcity, we realise that we have to deal with water differently.”

In industrial processes, water is used for cooling, purification and cleaning, and to transport heat. At Twence, water management is now a permanent item on the agenda.

Mapping the Entire Water System

Together with Mark Achtereekte, environmental engineer at Twence, and colleagues from several departments, Hegeman mapped the complete water system: from intake through use to discharge, and from use in the installations to processing in the administration. “That provided immediate insight and led to concrete savings,” says Hegeman.

Water is used at many points on the Twence site. It is needed daily in the flue gas scrubbers of the flue gas cleaning systems at the energy plants. It is also used to clean installations and to compost vegetable, fruit and garden waste. The site has its own water treatment plant, and rainwater from the roofs is collected in a large firefighting pond.

“For years, we looked at many of these water flows separately,” says Achtereekte. “It is precisely by looking at them together that new opportunities arise.”

Quick Measures With Low Investment

The team drew up a roadmap for smarter water use. According to Achtereekte, it started immediately with measures that could be implemented quickly and required relatively little investment. The water treatment plant was adapted so that it can process more water at peak times. At the composting and digestion installation, clean and dirty water flows are now separated, so the clean water can be reused.

The wastewater from Twence’s new CO2 capture plant is also relatively clean. “We now use it in the flue gas cleaning of the energy plants,” says Hegeman.

Membrane Bioreactor and Nanofiltration Under Review

Alongside the quick savings, the team is looking at opportunities for innovation. Achtereekte explains that Twence is investigating the optimisation of its membrane bioreactor and testing methods such as nanofiltration and denitrification. The treated water would then be suitable for use in the waste-to-energy plants. The company also plans to examine whether water vapour can be recovered from its production process.

Ultimately, Hegeman and Achtereekte hope to close the water cycles completely. “We see water as a valuable raw material,” says Hegeman. “With every step, we use water more smartly and prevent unnecessary use. That is how we give internal water flows a second life.”

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