Every AD plant operator knows the pattern. A digestate line that was running fine six months ago is now narrowing. A heat exchanger that used to hold temperature is losing efficiency. Meanwhile, a centrifuge that used to run a full shift without incident is throwing alarms. None of it looks urgent on its own. Then one day it is, and a line goes down mid-run.

Why it keeps happening

That’s struvite, a mineral scale that forms when magnesium, ammonium and phosphate crystallise together. This happens wherever digestate flows. It builds in millimetres on the inside of pipework you can’t see. Eventually, the pressure drop or the blockage forces the issue.

Digestate is rich in ammonium and phosphate by design, because it’s a by-product of breaking down organic material. On top of that, most AD processes run in the pH range where struvite forms readily. In other words, the conditions that make digestion work are close to the conditions that make struvite inevitable.

The real cost of manual descaling

The usual response is manual descaling. That means taking a line offline, physically chipping or acid-washing the build-up out, then putting it back into service. It works. However, it’s expensive in ways that don’t always show up on a single invoice:

• Unplanned downtime on lines that were meant to be running
• Labour hours spent on a job that often takes days to complete
• Corrosive acid handling, storage and disposal, with the operator risk that comes with it. What’s more, the formic and sulfuric acid used here are both heavily tied to fossil fuel production.
• Accelerated wear on the equipment being descaled. Harsh acid washing and mechanical breakout both stress the same surfaces repeatedly, so the next build-up can settle in faster.
• Third-party coordination to dispose of the waste the process produces

It’s a cycle, not a fix. So each repeat competes for the same labour hours and downtime budget as the rest of the maintenance schedule.

A safer, faster way to remove it

The alternative isn’t a different way of stopping struvite from forming. Instead, it’s a different way of removing it once it’s there. That means no harsh acid wash and none of the physical risk of manual breakout.

This is what Thrive’s struvite remover was built to do. It’s formulated using only 100% biodegradable compounds produced through microbial fermentation, with Generally Recognized as Safe (GRAS) status. To apply it, a specialised high-powered pump connects to the site’s existing pipework. This creates a closed loop, and the product circulates through it for up to four hours.

In lab and field trials, it achieved 100% removal of struvite build-up within that window. That’s work that would otherwise take days, done in a fraction of the time. Better still, it clears the line without corroding or wearing down the infrastructure. Afterwards, the waste can be fed straight back into the digesters. As a result, there’s no third-party disposal to coordinate either.

It’s already being used at AD sites dealing with exactly this pattern. The plants running it are seeing less unplanned downtime. They’re also seeing far less wear and tear on lines that used to need repeated acid descaling.