Ireland is in the midst of a craft brewery and distillery boom right now, and this requires some advanced technologies to handle vast amounts of waste.
Wastewater and how we are treating it is a topic not far from the headlines the past few years, with a number of warnings issued by environmental groups on the abundance of microplastics and microbeads.
Often unseen to the naked eye, this plastic was introduced into oceans and rivers through waste and is now beginning to appear not only in the creatures that live in these habitats, but in the food we eat, too.
This has made the lives of many engineers an awful lot busier, such as Dr Jenny Lawler, a chemical engineer from Dublin City University (DCU) and head of its membrane and environmental technology group.
While her research has a particular focus on helping wastewater-using industries to find ways to reduce their harmful effects and stay on top of Irish and European legislation, one of her recent projects has been within the booming craft distillery industry.
Backed by funding from US agriculture and brewing firm Alltech, Lawler is fascinated by the challenges posed by the vast amount of waste generated.
The biggest waste generated by distilleries is ‘pot ale’, a copper-rich residue of fermented wort left after a vat of whiskey has been distilled.
In conversation with Siliconrepublic.com, Lawler said that for every million litres of whiskey a distiller produces, another 10m litres of pot ale is left behind. If this wastewater was simply dumped and not treated, the damage caused to the environment would be enormous.
In the past five years, more than 25 new distilleries have opened in Ireland as the craft brewing craze continues. This results in more than 600m litres of pot ale and, because it has a very high chemical oxygen demand, it is a pollutant 100 times stronger than human waste.
For example, human wastewater in a treatment plant could contain between 600 and 900mg of pollutants per litre, whereas pot ale has as much as 65g per litre.
Turning waste into energy
Until now, pot ale has been turned into a syrup for use in animal feed for Ireland’s massive agriculture sector, but the amount of copper in it makes it unsuitable for sheep farming.
Lawler said that she and the team at DCU are looking to find an alternative that is not only better for the environment, but could potentially turn distilleries into cleaner energy sources.
“We’re looking at using a technology called anaerobic digestion that’s common enough in the UK, but not very common in Ireland yet,” Lawler said.
“Anaerobic digestion produces a gas that is rich in methane, which can be used in combustion to produce electricity and steam to use on site, to partially meet the energy needs of an industry. You’d have the potential for the site to be self-sufficient.”
Returning to the topic of microplastics, Lawler and many of her colleagues in the field are currently in the dark as to the potential damage (if any) from the consumption of said plastics.
A report earlier this year found that much of Ireland’s continental shelf showed traces of fragmented, miniaturised pieces of plastic and this would seem to be a cause for concern. For Lawler, however, the science just hasn’t reached a point where we can definitively say that yet.
“The chronic health impact of exposure to them is completely unknown – we have no idea,” she said, adding that many wastewater treatment plants in Ireland are just not advanced enough to remove or detect them.
“Some [treatment plants] will remove fats, soils and greases and would then send them to landfill. But we’re seeing you can get a lot of accumulation of microplastics and beads within those fats, soils and greases. Even if we remove 90pc of microplastics in a conventional wastewater plant with good technology, we’re still putting a lot of that back into the waterways.”
The good news is that the technology is rapidly catching up for our ability to both detect and stop microplastics in their tracks. Thanks to advances in imaging technology and analytical systems, researchers and facilities can now see contaminants at a nanogram-per-litre scale, which would have been impossible just a few years ago.
Throw on top of that the incredibly advanced membrane technologies being worked on by Lawler and her team, and you have a much more environmentally friendly and efficient system.
No need to scaremonger
The DCU team is working with the wonder material graphene, which has demonstrated an incredible ability to act as a water filter.
While other research teams wait for graphene to become more commercially available, Lawler is using the more porous but cheaper graphene oxide, which she describes as having “amazing” filtering abilities.
Nature, too, is inspiring the next generation of filters, with Lawler describing how the biocidal nanopatterns on the wings of the cicada insect could be replicated to stop bacteria from blocking wastewater filters.
As the science behind microplastics expands in the years ahead, she stressed that she is not in the habit of trying to put people off using plastics.
“It may be that there is no risk or it’s an acceptable risk, but the research has to back it up,” she said.
“I absolutely don’t want to scaremonger. Everybody needs to use plastics. It’s very difficult to live without them at this stage.”