Chemistry students save 3000 litres of water a week in the lab
AUTHORS: Monica Clements, Jonathan Hay and Anton Hamann, PhD students in the department of chemistry and polymer science
A group of PhD students from Stellenbosch University in South Africa have responded to their country’s water crisis by designing ingenious water-saving solutions and implementing them across their whole department.
The Western Cape region of South Africa is currently suffering from a very serious drought. Heading out of what is known as the ‘rainy season’, dam levels are only at about 31%. This is very worrying as we head into the summer months where we will see very little rainfall. As a result, residents of the area are taking every opportunity they can to save water.
A quick glance around any functioning wet chemistry laboratory reveals a heavy dependence on water, so our head of department Professor Peter Mallon set the postgraduate students a challenge to actively start saving water in all laboratories. The three of us, from the group of organic and medicinal chemistry, developed a model that could help.
We identified areas in the laboratory where large amounts of water were being consumed – rotary evaporators, bulk distillation of common organic solvents, and vacuum filtration setups all guzzle significant amounts of potable water.
We then designed what we call a closed cold-water recycling system (CCWRS) that makes use of a cooler box, garden hose, laboratory silicon tubing and a small garden fountain pump. Ice and a small amount of water is placed into the cooler box, which is then fed through condensers – for rotary evaporators or distillation – by the pump.
This setup has been running in some of the organic chemistry research laboratories since installation, for eight hours a day, Monday to Friday, without failure of any kind.
Not only is this method saving hundreds of litres of potable water per week, it is also more efficient – condensing even low boiling solvent vapours far more quickly. It also allows rotary evaporators to be placed anywhere in the lab – not necessarily close to a drain or tap. Furthermore, the use of this method lowers the probability of solvents pooling inside the Buchi pump, thus prolonging the lifespan of the pump.
In addition, a similar type of cooling system has been applied to setups for large scale bulk distillation of common organic solvents such as ethyl acetate, hexane and dichloromethane. This system is connected in series to the large bulk still and four smaller inert solvent stills. This larger cooling system is more efficient than using several smaller CCWRS’s, which would take up unnecessary space.
More recently, a smaller portable setup has been designed and built for reflux setups in the fume hoods. In this way, individual setups for fume hoods do not have to be built and installed, thus saving money and valuable space in the laboratory.
Some of the other initiatives were simpler and less technical – by placing smaller plastic tubs in large wash basins, we halved the amount of water used to wash glassware and in many cases students also share the soapy water that was tapped into the bucket at the start of the day.
Many of our synthesis labs and undergraduate labs are now operating these simple, cost effective water-saving devices. Our systems have been implemented in the first year laboratories for the nearly 900 students to carry out their reflux and distillation reactions.
It makes use of a recycling system that is set up in series that allows for one system to be used per bench. It is estimated that the systems running in the department will save between 3000 and 5000 litres of potable water per week.
We wanted to show that by using a little initiative, creativity and effort, we could save a great deal of water and money by using items that can be bought at low cost from local hardware stores.
We hoped that by getting our ideas started in our laboratory, this could be spread not only to the rest of our department and faculty, but also to other universities, schools in the area or even industry labs looking at saving costs in their laboratories.
As a department, we are continuing to look into other ways of improving our systems to save even more water.
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