Environmental technology solutions provider SEM was one of just six international businesses to secure a place in the recent final of the Water Dragons competition.

The competition, organised by the Future Water Association, offers companies the chance to pitch innovative services or products to a panel of senior water company executives and industry specialists.

SEM’s entry was the result of a joint project between the Aberdeen-based firm’s lead scientist and academics from Coventry University. Entitled ‘A Wee Dram’, the project applies SEM’s patented DRAM wastewater filtration technology to the challenge of biologically recovering precious (and other) metals and nutrients from wastewater treatment plants (WWTP) and industrial effluents.

The unique, sustainable technology uses both low carbon, passive filtration and naturally occurring micro-organisms to remove gold, silver and other metals from wastewater and effluents – a process termed bioleaching.

SEM’s lead scientist Dr Leigh Cassidy said: “At SEM we are committed to fostering the evolution of a circular economy. We harness naturally occurring or pre-existing substances such as by-products from other industries, to remediate wastewater, removing and recovering precious resources and nutrients which can, in turn, be re-used. What’s more, the spent DRAM media can then be used as a soil conditioner.

“With the Wee Dram project, we have applied our ground-breaking technology to tackle a number of challenging situations for industries and communities around the world. On one level, metals are an extremely valuable commodity, now more so than ever as we build increasing volumes of electric cars, wind turbines and solar panels. Currently, water companies across the UK stand to miss out on billions of pounds of potential revenue per annum from these unrecovered metals. They could also benefit from the increased value of the metal-free biosolids which remain after the bioleaching process.

“The environmental benefits of a Wee Dram are equally powerful. For example, each ton of metal extracted by traditional mining methods emits approximately 25.6 tons CO2 equivalent. The UK produces approximately 1.5 million tons of sewage sludge. If 1% of that is composed of metal, then 15,000 tons of metal can be recovered, equating to a carbon saving of 384,000 tons of CO2 equivalent. Unfortunately, much of the world’s metal is mined in conflict zones, where exploitation is rife – by re-using metal that is already in circulation, we can reduce the demand for new virgin metals, and thus the need for these mines.”

Daniel Ray of Coventry University explained how the technology works: “DRAM is an adsorptive treatment for liquid waste. It uses raw waste materials from other industries to remove a wide range of both dissolved and particulate contaminants, and has a very light carbon footprint. We have combined the DRAM technology with bioleaching, a process which utilises micro-organisms to make metals soluble, releasing them into the solution. Metals that can be bioleached include gold, silver, zinc, copper, lead, arsenic, antimony, nickel, molybdenum, cobalt and uranium.”

Grant Leslie, co-founder and COO of SEM, added: “A Wee Dram is yet another chapter of the SEM story, the core ethos of which is devising disruptive solutions for the recovery and re-use of valuable nutrients and resources. It showcases our capabilities in developing technology and implementing processes which contribute towards achieving the UN’s 17 Sustainable Development Goals.”

The final – which took place at the Canadian High Commission in London – was won by Canadian firm, FloNergia Inc.