Laurent de Franceschi

Laurent de Franceschi has spent the better part of three decades on one problem: how to use ozone to clean water that nothing else can. He is the Head of Applications at Veolia Water Technologies, which is the upstream, get-your-hands-dirty end of the job, doing the lab testing, the piloting and the development of new ozone applications under the long-running Ozonia brand. When he came on the (don’t) Waste Water podcast in July 2020, as my very first guest ever, he held the same role at Ozonia under SUEZ Water Technologies & Solutions, before that whole business moved over to Veolia in the 2022 SUEZ-Veolia combination. Same ozone, same job, different logo on the door.

Laurent de Franceschi works in ozone and what the field calls AOP, advanced oxidation processes, one of the water technologies that generate aggressive, short-lived molecules to rip apart pollutants ordinary biology and filtration leave behind. His own conviction, and it is a properly expert one, is that oxidation is the future for micropollutants but rarely on its own. The clever move, as he puts it, is to use ozone to break the big, toxic, stubborn molecules into smaller pieces that a biological process can then happily digest, so the two technologies finish each other’s work rather than competing for the job.

Laurent de Franceschi opened the whole podcast, in episode one, by answering a deceptively simple question: how do you actually solve a wastewater treatment riddle? His answer was a practitioner’s checklist rather than a sales pitch, and it is exactly the kind of grounded, source-it-yourself methodology the show has chased ever since. It starts with getting a genuinely representative water sample, because, as he warns, water quality is never constant and the sample you pick has to match the conditions you will really run in. From there you mine the data you already have (the internal database of prior tests, of which compounds react with ozone and which do not), you pilot it because the real water matrix varies and a pilot sits closest to real operating conditions, and then you team up to scale, pulling in the right partners. The secret ingredient he keeps circling back to is less technical: passion, and people before tools.

Laurent de Franceschi has watched the entire mindset of his field flip over the course of his career, and that shift is the thing worth listening to him about. In the 1990s, treating wastewater meant spending energy, effort and technology to make a problem go away, whereas today the goal has inverted toward pulling energy and value back out of that same dirty water. He points to biogas and biomethane fed into the gas grid, to phosphorus recovered from sludge, to the broad idea of treating wastewater as a resource rather than a nuisance. In his own words:

“In the '90s, when we were talking about treating wastewater, the idea was to put energy, to put effort, to put technology to treat water. Since two decades now, we are more focused on how to produce energy from wastewater, bringing added value to wastewater.”

Laurent de Franceschi is the kind of guest who teaches more than he sells, an applications engineer who has seen enough water to be calm about it, and a fitting first voice for a show that has tried to do the same thing ever since.