In channels where combined sewage and storm water are conveyed, there are also some coarse substances, such as grit and sewage related debris. These coarse substances usually move more slowly than the water flow and often cause problems with downstream plant and equipment. In principle the goal is to identify the sources of grit or debris entering the sewerage system and eliminate them to prevent sewage related debris within the sewer system. In reality however, debris will always be found in the sewer system. It then causes operational problems and mechanical damage to inlet or head works and pumping station equipment. The latter can be avoided, by installing grit and debris removal stations where the debris can be collected. By periodic draining and emptying smooth system operation can be maintained. This action directly affects the performance of downstream plant by significantly reducing the solids into the plant.
In conventional systems, a concrete chamber is installed in a sewer channel section to collect the grit. In this concrete chamber, aeration ducts are installed to aerate the grit. Air supply keeps the organic particles in suspension, so that they remain in the wastewater flow. Grit can be removed either with a stationary or mobile lifting device, or by means of vacuum suction vehicles. The grit removal is usually executed during operation, i.e. when the grit trap sewer is flooded. In this case there is a danger of damaging equipment or the civil structure with the lifting system. If the removal is carried out by suction vehicles, the inlet into the structure must be closed.
The BIOGEST® Grit Trap Type GESMO allows you to trap grit and debris from sewer networks in combined sewage-storm water and rainwater systems.