Sewers carry waste water and sewage from various locations to the treatment facilities. Waste water pipe lines are mostly separate from the sanitary sewer systems. Sanitary sewers carry sewage from houses and industries to treatment plants where it is treated for reuse. Sewage consists of domestic and industrial waste including urine, faeces, industrial discharge etc. If the drinking water supplies come in contact with the sewage, it can cause diseases or even death. Any leakage or seepage of sewage can result in ground water pollution.
Pumping stations in sewerage systems (lift stations) are designed to transport raw sewage fed from underground gravity lines. A sewage pumping station is installed to move waste water from lower level to higher elevation. The units are often designed as a factory assembled system including a wastewater receiving well (wet-well), along with lift pumps and piping equipped with valves, a junction box, and a control panel connected with an alarm system. Sewage is fed and stored in the wet well (for a very small detention time). When the level reaches a predetermined point, a pump lifts the sewage in upward direction through a pressurised piping system. It is then discharged again into a gravity manhole. The cycle keeps repeating till the sewage reaches the point of destination, generally a treatment plant.
Correctly designed wet well is vital for proper and trouble-free functioning of the pump station. Sewage pumps are mostly end-suction centrifugal pumps equipped with open impellers, and have a large open passage to prevent blockage or clogging. A sewage pumping station is generally required in cases where,
-the elevation of the source is insufficient for gravity flow;
-the basement is too low to allow the sewage to flow to the main sewer;
– the sewage must be lifted over a ridge;
-the sewage must be lifted to get adequate head for gravity flow;
-discharge outlets are much below the level of the receiving water body;
-using a gravity conveyance may lead to excessive excavation and increased construction costs.
Submersible pump stations typically cost less as compared to the stormwater pump station and do not need frequent pump maintenance to operate. These pump stations usually do not include huge above the ground structures and often blend well with the surrounding environment.
An efficient sewer system provides a high degree of comfort and hygiene. If the sewage is moved in a closed system which is capable of conveying higher elevations with no potential problem issues and without directly involving workers, the entire operation becomes even more secure. Wet wells overflows must be avoided and it is important to ensure that there is a treatment plant ready at the end of every sewer pumping system.