Grit Facts​

BLACK DOG ANALYTICAL

2402 E. 2659th Rd.

Marseilles, IL 61341

(815)-715-3123

What is Grit?

Grit has many definitions but according to the EPA..."Grit includes sand, gravel, cinder, or other heavy solid materials that are “heavier” (higher specific gravity) than the organic biodegradable solids in the wastewater. Grit also includes eggshells, bone chips, seeds, coffee grounds, and large organic particles, such as food waste". -EPA 2003

In general, it is considered sand, silt or smaller particles (less than 1000 micron) known as “grit” that can contaminate and clog downstream systems in wastewater treatment facilities.  It is important to note that while there are many theories about grit, there is no industry standard that defines it.  Some modeling shows that developing equipment based on particle shape and size.  Others use specific gravity as a more accurate means to determine settling velocities of particles. 

Ultimately, Black Dog Analytical uses a robust, non-biased sampling method with proven results that we are accurately able to collect grit below 50 microns.  This is well below most grit characterization chambers rated at 105 microns.  

Why remove grit?

Allowing grit to enter downstream processes in a wastewater treatment plant can cause erosion, abrasion and clogging, leading to larger maintenance costs and longer downtimes.  All WWTP have some sort of grit removal system, however; our studies have shown that most facilities are not operating anywhere near peak or optimal efficiencies.  Many grit systems work well when the flow rates are low, allowing more time for the grit to settle out.  During peak flow times however, the increase in flow allows grit to be carried through some of the grit separation units and into clarifier tanks and other downstream processes. 

Black Dog Analytical is experienced at sampling grit during peak operational conditions to get a “real world” analysis of the system as intended.  Our company provides single sample analysis or full grit chamber analysis to make sure your system is operating as intended.