Some applications require wastewater to be grinded into a slurry before it reaches a septic system or municipal sewer. Those places are where grinder pumps are most often found. These pumps are similar to sewage pumps, but they have the addition of a blade to grind up solids in the wastewater.
Grinder pumps can be best described as a sewage pump with a garbage disposal on its inlet. The blade turns the incoming wastewater into a slurry before it leaves the pump. Houses that are below the municipal sewer often use this style of pump.
Some models of grinder pumps have a float switch already included with the pump. That float switch allows the pump to activate or deactivate autonomously. When the water level is high, the float switch activates the pump. When the fluid level is low, the float switch turns off the pump.