Question

proposal for potable water or wastewater treatment

Answer 1

Waste water treatment

The term waste water is now increasingly used in place of sewage. wastewater includes both organic and mineral matter carried through liquid media. While the organic portion of the wastewater is putrescible, undergoing biological decomposition, the mineral matter may combine with water to Form dissolved solids, may form unsightly sludge deposits and may contribute to the hardness of the water in the effluent.

The wastewater treatment or sewage treatment is a broad term that applies to any process, operation or combination of processes and operations, that can reduce the objectionable properties of water carried waste and render it less dangerous and repulsive to man. Thus, the wastewater should be treated before it's ultimate disposal in order to:

a) reduce the spread of communicable diseases caused by the pathogenic organisms in the sewage and

b) prevent the pollution of surface and ground water.

Methods of treatment in which the application of physical forces predominate are known as unit operations, while the methods of treatment in which chemical or biological activity are involved are known as unit processes.

There are three constituents and interrelated aspects of wastewater management:

1. Collection of domestic and industrial wastewater is best achieved by a fully developed sewerage or water carriage system. The planning and design of wastewater collection facilities involves the determination of wastewater flow rates; the hydraulic design of sewers, large conduits, and junction and diversion structures; the selection of sewer appurtenances and pumping stations. Most sewers are laid under roads to avoid interference with private property when connections and repairs have to be made. Sewers are commonly laid in straight lines, man holes being provided at all changes of direction, gradient and diameter.

2. Treatment of wastewater is essential in order to reduce the spread of communicable diseases caused by the pathogenic organisms in the sewage and to prevent the pollution of surface and ground water. The treatment of wastewater is carried out by a combination of physical unit operations and chemical and biological unit processes, before the end products can be safely disposed off.

3. After the treatment, the problems of disposal arises. The most important recent trend in the field of disposal is the establishment of increasingly stringent requirements to protect the environment. Currently used effluent disposal methods are (I) dilution in streams and rivers (ii) land application and (iii) re- use in aqua culture and crop irrigation.