Graeme Pearce

Graeme Pearce did not set out to spend his life on membranes, because in 1980 there was barely a life to spend on them. Straight out of his chemical-engineering doctorate at Oxford, he joined BP Chemicals Research in Hull and was handed a brief to look at separation technologies for the oil and chemical industries, and as he puts it, he had not really heard of membranes at that point, since they were hardly used commercially anywhere. So the man who is now one of the field's go-to authorities wandered into it more or less by accident, working membranes alongside older tricks like pressure-swing adsorption and crystallization, at a time when nobody was sure membranes would ever earn their keep.

Graeme Pearce then rode the whole wave from the inside. He was part of the core team that spun BP's separations work into a company called Kalsep in 1988, and he watched the membrane business grow, in his words, like crazy through the 1990s, off the back of two things landing at once: the cryptosporidium scare, a chlorine-resistant bug that ordinary sand filters were letting through, and a wave of drinking-water legislation in North America and the UK. A membrane is a physical barrier, so it catches what chlorine misses, and suddenly utilities had a reason to buy. After Kalsep he spent five years at Hydranautics selling ultrafiltration and microfiltration kit, which means by 2005 he had seen the technology sold, designed, installed and, often enough, botched.

Graeme Pearce founded Membrane Consultancy Associates in 2005 for a reason that tells you exactly what kind of expert he is. The early gold rush, he admits, came with missteps, because suppliers were too aggressive in their plant designs and some of the first products had real weaknesses, and when you combine a weak product with an over-stretched design, a fair share of those plants were never going to work out. So he set up his consultancy to play referee: to advise both the suppliers and the users, to get the market to rein itself in and be more realistic, and to make membrane projects actually deliver instead of disappoint. That is the unglamorous, genuinely useful niche, the person you call when you need someone with no product to sell telling you which membrane claim to believe.

Graeme Pearce is at his most interesting on the technology he is best known for, the membrane bioreactor, or MBR, which is simply the biological stage of sewage treatment and a membrane barrier combined into one compact step. The detail he keeps coming back to is the one most people get backwards. In conventional wastewater treatment, he says, size is king: the bigger the plant, the cheaper the water, and you basically cannot run conventional treatment at small scale. MBRs flip that completely, because the tiniest MBR works just as reliably as a giant one, a big MBR being little more than a pile of small ones stacked together. That is why he sees MBRs as the route to distributed water reuse, cleaning water to a high enough quality right where you need it, instead of piping everything to one enormous plant and back.

Graeme Pearce is also refreshingly honest about the history he lived through, and he tells the wastewater side of it as a story of a lonely prophet. While the clean-water membrane crowd had governments and legislation on their side in the 1990s, the company pushing membranes for sewage, the Canadian pioneer ZENON (later swallowed by GE), spent years being told it would always be too expensive and never work, before the rest of the industry came round. Today Graeme runs membraneconsultancy.com, keeps a working blog on reuse and ceramic membranes and the slow churn of water legislation, and still talks like someone who finds the field genuinely fun, which, for a technology most people would rather not think about, is its own kind of recommendation.

“In conventional wastewater, size is king. Membrane bioreactors are the completely opposite end of the scalability spectrum: you can have the tiniest MBR and it can be absolutely fine and very reliable.”

Graeme Pearce is, in short, the membrane industry's in-house sceptic, the rare expert whose value is in telling you what will not work, which is most of why utilities and suppliers keep calling. You can hear his full plain-language tour of membrane bioreactors on the (don't) Waste Water episode below, or read the companion explainer on what a membrane bioreactor actually is.