Macerator pump
A macerator pump reduces rag, fibre and soft solids to a size the pumping system can pass without blocking. In industry the cutting is done either by an inline macerator fitted in the pipeline ahead of a separate pump, or by a grinder pump that cuts at its own inlet and pumps in one unit.
In more detail
The term gets used for three different machines, and that is where most of the confusion at enquiry stage comes from. An inline macerator cuts and does not pump. A grinder or chopper pump cuts and pumps together. The third is the small domestic unit that sits behind a WC in a house, which is a consumer product and a different market from the two industrial machines described here.
Cutting and pumping are two different jobs
Decide first whether you need to pump as well as cut, because that picks the machine. An inline macerator is a cutting unit in the pipeline with no hydraulic duty of its own. The pump downstream still moves the medium, and it stays exactly as it was specified. A grinder pump does both, with the cutter at its own inlet, which is why it can push unscreened sewage down a small-bore pressurised rising main rather than needing a large gravity sewer to take it.
The practical difference is what happens to the rest of the installation. Fit a macerator and the hydraulic selection downstream is untouched. Fit a grinder pump and you have replaced the pump, so the duty point, the motor and the rising main are all back on the table.
How the cutters actually work
Two mechanisms cover most industrial machines, and the wear falls in different places.
The first shears the solids between a rotating blade and a perforated cutting screen as the medium passes through. On the Vogelsang RotaCut the blade rotors are asymmetric, a movable bearing holds them in continuous contact with the screen, and the screen is reversible so both sides get used before it is scrapped. The unit carries an integrated heavy material separator that drops stones and metal parts out of the flow before they ever reach the cutter head.
The twin-shaft machines work differently. The Vogelsang XRipper turns two shafts of hardened Ripper rotors at different speeds, so material settling in the gaps between them is raked out rather than left to bind, and counter-cutters on axial wear plates stop debris slipping past uncut.
Where a macerator earns its place
The enquiry that turns into a macerator usually does not start as one. A pump is clogging constantly on rag, and the request that reaches us is for a better solids-handling pump.
That is worth checking before anyone quotes. Where the pump already fitted is a good solids-handling pump, a like-for-like swap fails the same way, because the rag was never the pump's fault. It is arriving at the wet end because nothing upstream takes it out. The answer is rag removal ahead of the pump, which means a macerator or a chopper pump, and that is a system change rather than the purchase being asked for. It is an enquiry we turn down rather than fill.
Rag is the first of the three things that kill pumps on a wastewater works. Grit is the second, and a macerator does nothing about it. If grit is abrading your wet end, the grit removal on the works is what wants attention.
What it costs you
The cutters are the wear part, and they are meant to be. They take the wear so the pump behind them does not, and they get changed on a schedule. Grit shortens their life, so on an abrasive duty put cutter replacement into the running cost before you compare a macerator against the alternative.
You are also adding a machine to a line that did not have one. That is capital cost, a motor to power, and one more thing to maintain and to isolate when it needs attention. And when the pump downstream starts ragging again, check the cutters first. It is usually them and not the pump.
What we supply, and what we do not
We supply the industrial machines. Our macerators and disintegrators are the inline cutting units that sit ahead of the pump you already have, and grinder pumps cover unscreened sewage into a small-bore rising main.
Domestic bathroom macerators, the small units behind a WC in a house, are a consumer product and not a market we serve. If that is your duty, a merchant will serve you faster and more cheaply than we will.
Send us the flow, the medium, its dry solids content and what the rag actually is. Those set the cutter type, the cutting screen and the drive. We specify the macerator alongside the pump it is protecting rather than on its own, because the two get selected together.
Frequently asked
What is a macerator pump?
A macerator pump is an industrial cutting machine that reduces rag, fibre and soft solids so a pumping system can pass them. It is either an inline macerator that cuts and leaves the moving to a separate pump, or a grinder pump that cuts at its inlet and pumps in one unit.
What is the difference between a macerator and a grinder pump?
A grinder pump cuts and pumps in one unit, so fitting one means replacing the pump. An inline macerator only cuts, which leaves the hydraulic selection downstream exactly as it was.
Where is a macerator fitted?
In the pipeline, ahead of the pump or the process it protects, so the medium arrives already cut. Machines are also built for standalone chambers and for direct channel or shaft mounting where the pipework will not take an inline unit.
Can a macerator handle wet wipes?
Yes. Wipes are the rag that binds up a wet end, along with textiles, plastics and sanitary items, and cutting them before they reach the pump is the whole reason for fitting one.
Is a macerator pump the same as a domestic bathroom macerator?
No. A domestic macerator is a small consumer unit behind a WC, sized for one bathroom. An industrial macerator handles sewage, sludge and process media at works scale and is not something you fit in a house.
Do macerator cutters wear out?
Yes, and that is what they are for. The cutting tools take the wear instead of the pump and get replaced, fastest on gritty duties, so cutter replacement belongs in the running cost from the start.
Will a macerator fix a pump that keeps blocking?
Only if rag is the actual cause. Cutting upstream stops rag reaching the wet end, but it does nothing for grit abrasion or for suction conditions that were never right, and those account for most of the rest of what kills a wastewater pump.