Researchers seek to reduce laundry wastewater by 90%
21/08/2019
Warsaw University of Technology (WUT) is taking part in the Reward project, which wants to recover and reuse most of the water used in the washing process as well as some detergents.
“Industrial laundries use up to 10 litres of water and 6 grams of detergents per 1 kilogram of dry textiles,” said Maciej Szwast, leader of the WUT team.
“For laundries with a daily capacity of 15 tonnes of textiles (notably hotel and hospital bed linen, workwear, staff and hospital wear), the daily water consumption touches a whopping 150,000 litres and the detergent consumption is about 90 kilograms.
“For membrane filtration, we use our proprietary micro/ultrafiltration membranes; these are filtration materials with pores sized in the range of fractions of a micrometre,” explains Mr Szwast. “Water with dissolved compounds, including detergents, flows through a membrane. But elements which are larger than the membrane pores, in particular, solid particles of dirt as well as fats and proteins are held back.”
The resulting filtrate can be reused in the washing process.
“Dipole induction is a method chiefly known in the metals industry,” he adds. “Here, a specially designed electrode charges solid particles (in this case, these are textile fibres or particles of dirt) so that they would form larger aggregates for easier separation on the membrane.”
He says membrane modules have been fitted in washers for a few years. “But they are only intended to treat the water discharged to the sewer. It seems, we are the first to have addressed the issue of closing the water flow in laundries.”
Work is under way to reduce the quantity of laundry detergents added to subsequent washing cycles and to prepare economic analyses of the solution.
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