Collection And Conveyance Of Sewage

INTRODUCTION

Collection of wastewater is done by a sewerage system. Sewerage systems can be classified into combined sewerage and separate sewerage. Merged sewerage carries stormwater and wastewater both, although separate sewerage carries stormwater or wastewater separately. Present trends have been for the development of separate sewerage systems. The major purpose for this is that stormwater is commonly less polluted than wastewater, and which treatment of combined wastewater and stormwater is hard during heavy rainfalls, resulting in untreated overflows. In practice, there is commonly ingress of stormwater within wastewater sewerage pipes, since of unsealed pipe joints, and unintentional or illegal connections of rainwater runoff.

The goal of a public wastewater collection and conveyance system is to ensure in which sewage (or excreta and sullage) discharged from the communities is properly collected and transported to the treatment plant and disposed off without causing any public health and environmental problems. Stormwater and surface runoff could cause important public health and environmental problems. Flooding, soil erosion, and water pollutants such as pesticides, fertilizers, oil, organics and other substances are a few of the major problems related along with uncontrolled stormwater and surface runoff. Increasing urbanization has raised the frequency and severity of these problems. It is, thus, essential to provide storm drains for the removal of excess water from the streets, parking lots, parks and gardens.

Main role of the sewer system could be listed as

• Improvement in the living environment through removing and treating wastewater discharges,
• Prevention of inundation through removing rainwater,
• Preservation of water quality in public water areas, and
• Necessary element of the urban infrastructure in supporting wholesome and cultural urban life and urban activities.

Providing an adequate sewer system for the area needs careful engineering. It should be properly and skillfully planned and designed so as to transport the whole sewage effectively and efficiently from the houses and up to the point of disposal. The sewer must be adequate in size or they will overflow and cause property danger damage, to health and nuisance. Adequacy in size of sewers calls for correct estimation of the amount of sewage and use of hydraulics to determine proper size and grades of sewers that will permit reasonable velocity of flow. This flow should neither be too large as to needs heavy excavations and high lift pumping nor should it be too small to cause deposition of solids in sewer bottom with accompanying odours and stoppages.

Sewer appurtenances are devices essential, in addition to pipes and conduits, for the proper functioning of any complete system of sanitary, storm or combined sewers. These appurtenances include manholes, lampholes, flushing tanks, ventilation shafts, inverted siphons, inlets, catch basins, junction chambers, diversion chambers, tide gates and other structures or devices of special design.