SOLVE magazine Issue 01 2020 - Page 20

SUSTAINABILITY AND THE ENVIRONMENT: ENVIRONMENTAL ENGINEERING Circular economy spins waste into a resource Dr Fay Couceiro is trialling technology that cleans up the environment and boosts agriculture by extracting a valuable nutrient from an unlikely source – human waste. Too much phosphorous in the environment can be damaging. In waterways it can cause eutrophication, where nutrient overload results in algal blooms, reduced oxygen and suffocated fish. However, in the right place phosphorous – a naturally occurring chemical – is incredibly useful. It helps promote plant growth and vigour, and is a critical fertiliser needed by farmers to grow our food. Worryingly, the world is running out of phosphorous; there are very few phosphorous-rich rock deposits left to mine. As stocks dwindle, fertiliser prices will rise and crop yields will fall. Another source of the element has to be found. Enter the University of Portsmouth’s Dr Fay Couceiro, whose cross-disciplinary research is addressing these issues – environmental threats and resource depletion – simultaneously. She is trialling technology that not only removes excess and damaging phosphorous from waterways, but also potentially repurposes it for agriculture. And unlike the current, finite phosphorous resource, the alternative source will be around for as long as humans are around; it will come from human waste. Dr Couceiro, from the University’s Department of Civil Engineering and Surveying, explains how there is a lot of phosphorous in sewage – Fay Couceiro sewage that, once treated, is expelled into waterways. “There’s only so much phosphorous on the planet and we are throwing it down the toilet, quite literally, and out into the rivers,” she says. “So we need to capture and use it.” Working with Southern Water, at a Petersfield trial site, Dr Couceiro is using absorptive media – a filter bed of specially engineered media that adsorb phosphorous as treated sewage flows through the bed at discharge points. “We are working on low-tech methods for removing phosphorus because many sewage treatment works are unmanned,” she says. “This technology doesn’t need any energy to operate, and the only difference between the water entering the media and coming out the other side is it contains less phosphorus.” Dr Couceiro can’t disclose the composition of the media due to commercial confidentiality, but has trialled several variations, and the most successful is now being developed. Nutrition cycle Once the media have extracted it, the phosphorous could either be ground into a fertiliser if it is of high enough quality, or sold for use in other high-end products such as light-emitting diodes (LEDs). Research on end uses for the extracted phosphorous is ensuring its effectiveness and safety. ILLUSTRATION: 123RF The science is creating a serendipitous circular economy, reflecting an interconnectedness that has long been at the heart of Dr Couceiro’s research. As a biogeochemist she looks at biology, geology and chemistry together, analysing how the disciplines interact in aquatic settings for better environmental outcomes. “There’s a gap in our knowledge about how these things interact with one another. If you only focus on the biology or the chemistry you tend to lose how they’re connected. So it’s those connections that I look at,” she says. “Biology affects the geology; it affects how the seabed forms and then the seabed affects the chemistry because it affects how the nutrients get into the water, and then the nutrients affect the biology because that decides how many algae will form for the following year. So, it’s that circular session.” Dr Couceiro’s broad body of research that revolves around removing contaminants from aquatic environments has led to cleaner waterways in a variety of places, from the once-toxic Mersey Estuary to the Caribbean Sea. While she is the first to admit that working with sewage is not as spectacular as some of her other work, such as diving off volcanoes in the Caribbean looking for heavy metals expelled from vents, it is potentially more impactful. “We’re talking about a huge reduction of phosphorus going into rivers, hopefully less eutrophication, less algal bloom incidences, less fish deaths from low oxygen levels,” she says. “And if that phosphorus can instead go to farmers or other end users, we are transforming wastewater from a waste to a resource.” Dr Couceiro says she is driven by a desire to leave the world “a little bit better” than she found it. “I want to stop anything from microplastics and phosphorus, nitrogens, pesticides, pharmaceuticals – all these things coming out into the environment that are damaging wildlife – and if I can, in any way, help, I would like to.” 20 ISSUE 1 / 2020