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Chemistry students save 3000 litres of water per week in lab
Author: Media and Communication, Faculty of Science
Published: 14/09/2017

Three chemistry students at Stellenbosch University (SU) have reduced their laboratory’s water consumption by at least 3 000 litres per week by coming up with innovative and relatively inexpensive ways of saving water.

Four months ago PhD students Monica Clements, Jonathan Hay and Anton Hamann started to conduct trials in the medicinal and organic chemistry laboratory in the De Beers Building in response to a challenge put out by their head of department, Prof Peter Mallon, to develop ways of saving water.

“With the water shortages in the Western Cape, we started talking about how we could reduce water consumption in our lab. This has led us to a number of changes in the way we operate water-consuming instruments,” they explain.

They first identified the largest consumers of water and then developed a system – called a Closed Cold-Water Recycling System (CCWRS) – to be used with various water thirsty lab equipment.

The closed system consists of a cooler box, a garden hose and laboratory silicone piping, as well as a garden fountain pump of 80L/h. The basic principle is that the water is cooled down with ice and then recycled in a closed system, whereas previously perfectly potable tap water would have gone down the drain.

The first major water-user identified was the lab’s rotary evaporators, which used over 100 litres of water per day when running directly from the tap.

The evaporator’s condenser is now connected to the closed system and not to a tap, and only uses about five litres of ice water per day.

“All three of our rotary evaporators have been running on this setup, without failures of any kind even though running eight hours a day, Monday to Friday,” Jonathan explains.

They also found that this method of using ice cold water allowed the solvent to condense far quicker, and that it is also far more effective in condensing low boiling solvents.

Another significant water user is the vacuum suction filtration process, which consumes significant quantities of water in a very short space of time. Instead of each student making use of their own water suction filtration setup in their fume hoods, the lab now has one setup with a Buchi pump which uses no water at all.

“This method of filtration was recently applied in the undergraduate laboratories, where the amount of water saved thus far has been massive. In addition, this method has the advantage of being significantly more efficient – resulting in a much faster and drier filtration step that allow students to continue to the next step more quickly,” the group explains.

Their next target is to implement the closed cold-water recycling system in the reflux setups: “In a synthetic laboratory reflux setups is a common occurrence and currently makes use of municipal tap water to cool the condensers. It is estimated that a 24h reflux uses 180-200 litres of potable water. We are now conducting trials to see how best the CCRS can be used in this process.”

Not all initiatives were technical. By simply placing smaller plastic buckets in the large wash basins, they significantly reduced the amount of water used to wash glassware. Now one bucket filled with hot water is usually sufficient for washing two students’ glassware a day.

Prof Willem van Otterlo and Dr Margaret Blackie, the research group leaders for the laboratory, say they hope this initiative will motivate other research laboratories to look for innovative ways of saving water.

Prof Peter Mallon, head of the Department of Chemistry and Polymer Science at SU, says this is an outstanding initiative on the part of the postgraduate students: “It shows a high degree of responsibility and social engagement on their part.  We have recently instituted these water saving measures in our first year laboratories, where nearly 900 first years are now using it,” prof Mallon adds. Monica Clements.jpg

On the photo, Jonathan Hay (left) and Anton Hamann with the Cold-Water Recycling System (CWRS) they developed, together with Monica Clements (on the right), currently in the USA. It consists of a red cooler box connected to a laboratory rotary evaporator supplying ice water to the condenser coil. Photo: Wiida Fourie