Sewage Grinder Vs Macerator: Which Is Better?

Sewage Grinder Vs Macerator: Which Is Better?

Having solids in your waste water systems are inevitable. Sticks, wet wipes and the most random objects will somehow creep into treatment plants where the wastewater is being treated.

To prevent these from getting in we have screens but no matter the type of screen whether step, drum or perforated, some debris will always find its way in.When the screen fails the next step is to have solid reduction machines in place. There are 2 main types of solid reduction equipment and what’s best for your process will depend on a number of things.

Wet wipes, tissues, hair, rags, small plastics, strings, plastic bags, applicators can all easily pass through screens and damage, block or even clog downstream valves, pumps and other equipment used to process wastewater. This will increase costs and downtime drastically.

So, this is article for those who plan on introducing a solid reduction system to control the increasing costs creeping into your treatment plant.

Macerators vs Twin-Shaft Grinders

The first step of solid reduction is screening and after this it can be broken down into two categories: Grinders and Macerators.  Let’s take a look at each type.


This type of wastewater solid reduction works best when fitted right after the main screen or headworks system. Macerators are made to completely cut any debris that flows through them. However, these cannot cut heavy solids like metals and rocks, so they instead have removal traps for heavy debris.

Twin-Shaft Grinders

As the name suggest this type of solid reduction machine has 2 shafts that counter operate. Each shaft has sharp blades attached to them.As the blades rotate, they pull debris towards the centre of the blades. This is a straight system and has no debris trap.

What type of equipment is right for me?


This type of equipment is made for pipe installations are in-line. For solid reduction there should be liquid through the pipe because they cannot run dry. They are also ideal for small solids and cannot cut through large solids. This is don’t mean macerators are useless. Small solids can sometimes be as troublesome as heavy solids.

Macerators have defined cuts similar to a scissor, the liquid is responsible for moving the liquid through the blades.

Twin Shaft Grinders

Unlike macerators this type of equipment can be fitted with both in line and channel installations. They can run dry without any liquid to take the debris through the cutting element. They can handle large solids.

They don’t have a defined cut and just tear solids apart. Compared to macerators grinders require high pressure and torque to operate.

When it comes to wastewater treatment both these systems can be used in several applications. Some examples are Headworks pump station, septage receiving, GOD receiving, primary scum, pump protection, RAS/TWAS sludge etc.

Every situation poses different challenges so therefore to cover most of these challenges you’ll find that a grinder will work best initially while a macerator is often required as you progress into the wastewater treatment process.