Pore Performance: One 3D-printing firm's ambition to re-engineer membranes

Article by Adam Duckett

Adam Duckett interviews Tom Pugh and Andrew Walker about Evove’s push to improve separations

EVOVE wants to disrupt membrane technology. Using modelling and 3D printing, it has ambitions to change how membranes are designed, made, and who makes them while improving filtration performance, cutting energy use, and championing water conservation. These ambitions received a significant boost in November when the UK-based firm was picked from among more than 1,700 applicants to demonstrate its technology with brewing giant AB InBev (of Budweiser and Stella Artois fame) and Coca-Cola.

The company, which is based in Daresbury and employs around 30 staff, is developing various products that it says enhance the performance of membranes used to process liquids and recycle discharged waters. These include graphene-oxide coatings to reduce fouling of ceramic hollow-fibre membranes; 3D-printed inserts that are designed to optimise fluid dynamics in tubular and hollow fibre membranes; 3D-printed spacers with novel geometries to reduce energy use in the likes of spiral-would membranes; and 3D printed membranes that have more uniform porosity than those manufactured conventionally.

I spoke with Tom Pugh, a materials chemist, who says two crises led him to Evove where he now works as the VP of Customer Success. His role involves managing the technical aspects of the business and working with customers to understand their needs.

His first “existential crisis” struck while studying for a post-doctorate in magnetic materials.

“The overall feeling was ‘I don’t think anything I’m doing is ever going to see the light of day within my lifetime’. So, I was in search of something where I could have an impact on the industrial world.”

Pugh moved into sales for film materials but after a time he realised that technical development was what he really enjoyed, which brought him to Evove. The diversity of his colleagues’ backgrounds and expertise is helping Evove to approach membrane design from a fresh direction unencumbered by conventional thinking, he says.

“We have some expertise in fluid dynamics, engineering chemistry, but we’re not specifically coming from a [water industry] background…What that means is we look at things and we scratch our heads and ask: ‘Why is that the case?’.”

Prototype: Evove’s 3D-printed ceramic membrane technology

Membrane elements redesigned

“So let’s start with spacers,” Pugh says. “Perhaps the spiral element is one of the most well-known membrane types for the reason that it packs a large amount of area into quite a small volume.”

Spacers sit atop the membrane so that when it’s rolled into a spiral, they separate the layers, providing a cavity for the liquid to flow. Conventionally, they are made by extruding a polymer but this limits the geometries of the spacers that can be created.

Evove is 3D-printing its spacers to create novel shapes, and using computational fluid dynamics to model flow through the membrane to optimise spacer design and the effective use of the membrane surface area. Pugh says the technology can help reduce pressure drop and the extra energy required to overcome it.

“The input pressure will reduce over the course of the membrane to an output pressure generating a middle value, which is the TMP or transmembrane pressure,” he says.

“If you’ve got a big pressure drop, you have to have big input pressure. It is as simple as that. Big input pressure and big input flow, which means high energy costs. So, the geometries and designs that we produce are tailored and modelled and understood to minimise pressure drop. We can identify high performance spacers, ones that are generating a higher permeate flow, so we’re getting more out of each membrane element.”

Pugh says it’s helpful to think of the efficiency gains in terms of specific energy consumption, that is how much energy it costs to process a unit of volume. If the flux can be increased by 20% while maintaining the input pressure and flow then the operation has 20% less specific energy consumption, he explains. Consider the number of desalination operations running today and the growth in installations required to meet rising freshwater demands and Pugh says the implications of a 20% saving are huge.

“A 10-20% increase in in flux is what we can achieve right now and these are non-optimised designs, at prototype stage. Realistically we see this being further towards 50%. In terms of the specific energy consumption, again if we manage pressure drop, the figures are probably more like 30% or 40% energy savings.”

The company is also modelling and designing asymmetric inserts, which can be thought of as spacers for tubular membranes, that save energy use by increasing surface velocity to help reduce fouling but reduce feed flow input.

“We can reduce the capital expenditure of the systems using these inserts because we’re not delivering as much feed flow volume. We use less steel. We have smaller ID [inside diameter] pipes. We have a smaller pump. All of which gives you an initial capex saving but then also your ongoing opex.

“Off the back of pilots, we’ve done with juice processing clarification for example, we’ve seen energy savings in the region of 70-75% as an operational saving in addition to a capex saving in the region of probably 15-20%.” Evove’s coatings range and inserts are commercialised. Pugh says the 3D-printed spacers are at technology readiness level (TRL) 6 and he expects to demonstrate and perform pilot tests in the coming months. The company is also working to develop 3D-printed membranes.

Article by Adam Duckett

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