When it comes to comparing Gravity style grease interceptors and Hydro-Mechanical

style grease interceptors, the bigger box does not necessarily hold more. This is because of the

fact that Gravity grease interceptors require a large volume of water to accomplish

separation. As the water volume diminishes (is replaced with grease), so does their

efficiency. Because Hydro-Mechanical interceptors rely on the inlet diffuser to slow down and

diffuse the incoming waste stream, and keep the influent from disturbing the existing grease layer, they can

utilize nearly all of the volume of their tank to store grease and solids.



BOTH OF THE INTERCEPTORS PICTURED BELOW ARE AT THEIR RATED CAPACITIES

 

 

There are also a couple of other fundamental differences between a Concrete grease interceptor
(gravity style)and a Hydro-Mechanical grease interceptor:

- Gravity style interceptors do not perform consistently across varying flows. At high flow rates,
the grease retention time is reduced, and they pass through more grease.

- Hydro-Mechanical grease interceptors perform consistently up to their rated flow. They have the same
grease separation efficiency regardless of what the incoming flow is.

- Gravity style interceptors are subject to "channeling". As they become full, the incoming influent "pushes"
a path through the interceptor. Much like a river eroding away at the banks as it winds downstream, this
channeling allows grease to be pushed through the interceptor.

- Hydro-Mechanical interceptors are not subject to "channeling". Because the inlet diffuser slows down
the flow of the incoming influent, the grease stored in the unit is not disturbed by the incoming influent.
This allows for greater grease storage capacity, and eliminates grease pass through.

(The above referenced information can be found in the WERF Report. The WERF Report is widely
acknowledged to be the most comprehensive study of Grease Interceptor Performance to date.)

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