Washing hands despite lack of water

phys.org | 10/22/2018 | Staff
morica (Posted by) Level 3
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Even though the water we've used for washing hands is barely contaminated, it usually goes down the drain. A newly developed system allows handwashing water to be recycled, thus not only saving water, but also helping to prevent infectious diseases in developing countries.

Every year, according to WHO figures, around four million people die as a result of diarrhoeal diseases or respiratory infections. Particularly in developing countries, these deaths are largely attributable to poor hygiene – the problem would be significantly alleviated by regular handwashing. But how can this be achieved in places where people lack access to safe water, or piped water is unavailable?

Issue - Group - Engineers - ETH - Professor

This issue is being addressed by a group of environmental engineers led by ETH Professor Eberhard Morgenroth (Head of Process Engineering at Eawag), carrying out research as part of the Blue Diversion Autarky project. They have now developed a grid-free treatment system allowing greywater – relatively clean wastewater from showering, bathing or handwashing – to be repeatedly recycled.

As Morgenroth points out, while commercial systems are already available which enable greywater to be treated on-site for use in toilet flushing, the recycled water does not meet the required quality standards to be used for other purposes.

Water - Treatment - System - Morgenroth - Team

This is not true of the water treatment system developed by Morgenroth's team over the past seven years, in collaboration with microbiologists, social scientists, urban planners and industrial designers: after several treatment stages, the greywater is odour‑free and colourless, with a bacterial count lower than that of Zurich tap water.

The key component of the system is a fine-pored plastic (ultrafiltration) membrane, which retains pathogenic organisms. The microbial biofilm which develops on the membrane breaks down the fecal and urinary contaminants in wastewater. However, because nutrient concentrations in handwashing water are relatively low, biological treatment performance rapidly declines: in a study recently published by...
(Excerpt) Read more at: phys.org
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