From waste to wealth
Most of us give little thought to what happens to the wastewater that gets washed away into our drains and sewers, but Dr Rachel Gomes has dedicated her career to studying what happens after we flush.
Wastewater or sewage is often seen purely as a problematic substance that needs to be treated and cleaned to prevent damage to the environment.
But Dr Rachel Gomes and fellow researchers at the University are exploring the potential for treatment plants to do far more than just clean.
The water that gets removed from our homes and businesses contains valuable materials which, if they could be captured, could be turned back into useful resources. Take copper for example. It’s found in much wastewater, particularly that from agriculture and other industries. “We tend to see wastewater and treatment plants just for delivering water, but the larger story of waste is changing,” said Dr Gomes.
“It’s not just about water. It’s pollutants to products, waste to wealth.” Rachel’s research is focused on developing analytics and treatment technologies to inform wastewater treatment and potential chemical manufacture from sources of wastewater.
"We tend to see wastewater and treatment plants just for delivering water, but the larger story of waste is changing"
Alongside colleagues she is studying the way copper can be recouped from wastewater on the University’s dairy farm at the Sutton Bonington Campus. Many animal feeds contain the element and it is also used in foot baths – although not on the University farm – so there’s potential for usable concentrations to be retrieved from the wastewater.
Traditional mining methods only need copper to be present at 0.2% within the ore for it to be commercially viable, so the opportunities present- ed by wastewater are vast. Dr Gomes said: “Cows walk through the foot bath. That foot bath will end up in the slurry tank. Well, instead of sticking it in there – it’s got a high copper and zinc load – why don’t we use that as a feedstock to then extract our metals of interest, rather than adding metals to the environment?
“There are opportunities for treatment you can have which still ensure the health of the herd, but can mitigate pollutants and in some cases turn them in to products.” Recent graduate Dr Ian Clark has carried out research on layered double hydroxides (LDH), a type of absorbent material, which copper can attach to.
PhD student Jacob Smith is continuing this work working with Dr Gomes and Professor Ed Lester on the opportunities novel material sorbents have for moving a pollutant from a waste- water into a product that has value.
Dr Gomes said: “It will allow you to transfer a pollutant, in this case copper, from a liquid stream onto the solid material, which then allows you to then purify and clean up to get your copper.”
"We are bringing together our engineers, scientists, geographers, historians, health experts and many more, to pioneer new ways that ensure every person and ecosystem on our planet has access to the water they need to thrive."
Her recent visit to India also demonstrates that what may be copper today could well be pharmaceuticals tomorrow. Sorbent materials could be used to recoup drugs present in wastewater from the pharmaceutical manufacturing process, offering value to the company and ensuring better water quality to the rivers receiving these wastewaters.
Dr Gomes, who joined the University in 2011, admits a large part of the attraction of Nottingham was the access and relationship with Severn Trent Water and its treatment processes. “There’s some super cool treatment works here!” she said.
She teaches water treatment engineering and these strong links with Severn Trent are something she uses in both research and teaching, and is keen to nurture. Students regularly visit its sites and carry out sampling from treatment works.
Dr Gomes is Head of the Food, Water, Waste Research Group, an interdisciplinary group aiming to deliver sustainable solutions to global challenges in these areas. “We have process engineering, environmental sciences, and modelling and analytics to name a few, so as a group we’re very cross-disciplinary, and our PhD students and postdoctoral researchers include chemical and environmental engineers, to chemists, microbiologists, and mathematicians.”
This inter-disciplinary research is something she is hugely passionate about and Dr Gomes is also part of a growing water research network of 125 academics across all five faculties and three campuses. “We are bringing together our engineers, scientists, geographers, historians, health experts and many more, to pioneer new ways that ensure every person and ecosystem on our planet has access to the water they need to thrive.”
Dr Rachel Gomes is an Associate Professor in the Department of Chemical and Environmental Engineering. Follow her on Twitter for more updates about her research.