Aerated Grit Chambers

The next step after coarse screening is to remove smaller objects (such assand, broken glass, silt and pebbles). There are three principal types of gritremoval systems: gravity channel, Aerated grit channels and vortex grit traps.Gravity Channels are sized to produce a certain optimum maximum flow velocitythrough the channel. Up to this velocity the majority of grits will fall out ofsolution and be collected in a bottom dump pit in the channel. These channelsare long, narrow, relatively deep and aerated with coarse bubble diffusers.Aerated channels are usually used in larger sewage works and may be equippedwith a mechanized grit removal device and a conveyor system to a bagging bin.
Vortex grit traps such as the Pista or Jetta types remove the grit from sewageinflow in a mechanized vortex flow container.

Process description:
In order to achieve an efficient grit removal, Mojan Co. provides the gritchambers with traveling bridges. Mojan Mechanical traveling bridge on two bogiestravels slowly back and forth on the grit chamber concrete walls after a pre-settime.
These bridges are equipped with a bottom sand scraper and a surface scumskimmer. During its forward motion, collects the scum and oily floatingmaterials using its scum skimmer and conducts it to scum box which is located bythe grit chamber wall. While during the return, it scrapes the settled particlesto a concrete hoper using its bottom sand scrapers. Then, the grit gathered inthis hoper is pumped toward a grit washer and dewatering unit .Grit washing isintended to remove any organic solids bound in with the grit, and return them tothe treatment plant. Mojan co. grit removal systems can be equipped with deepaeration systems. The airflow to the grit chamber will prevent the relativelylighter organic solids from settling out with the grit, and to prevent septicodors in the wastewater

Application:
Mojan traveling bridges are widely utilized in sand and scum (grease) removalunits in both municipal and industrial wastewater treatment plants.

Main Advantages:
Efficient separation of liquid and solid phases
Low energy consumption
Economic design
Low maintenance costs
Easy to installationLong life