Upload
-
View
222
Download
1
Embed Size (px)
Citation preview
Asif uz zaman(Lecturer)
Civil Engineering DepartmentFaculty of Engineering
RabighKing Abdulaziz University
Water Quality� Water quality can be defined as the current status or
condition of the water in a specific aquatic ecosystem.
� Activities such as fishing, swimming, boating, shipping,and waste disposal have different requirements for waterand waste disposal have different requirements for waterquality.
� Water of a particular high quality is needed for drinkingwater supplies.
� In many parts of the world, the introduction of pollutantsfrom human activity has seriously degraded water quality,even to the extent of turning clean streams into foul opensewers with few life forms and fewer beneficial uses.
Water quality� Water that does not impart a taste or odour and is,
therefore, pleasant to drink, is called palatable.
� Water that is free of chemicals, micro organisms, andother contaminants, and is, therefore, safe to drink, isother contaminants, and is, therefore, safe to drink, iscalled potable
� We expect our water to be both palatable and potable.
Drinking water qualityThe following four categories are used to describe
drinking-water quality.
1) Physical: Physical characteristics relate to the qualityof water for domestic use and are usually associatedwith the appearance of water, its colour or turbidity,with the appearance of water, its colour or turbidity,temperature, and, in particular, taste and odour.
2) Chemical: The chemical characterization ofdrinking water includes the identification of itscomponents and their concentration.
Contd..3) Microbiological: Microbiological agents are
important to public health and may also be significantin modifying the physical and chemicalcharacteristics of water.
4) Radiological: radiological factors must be considered4) Radiological: radiological factors must be consideredin areas where the water may have come in contactwith radioactive substances. The radioactivity of thewater is of public health concern.
Potable water classification� Potable water is most conveniently classified as to its source,
that is, ground water or surface water.
General characteristics of Ground water and Surface Water
Ground Water Surface Water
Constant Composition Varying CompositionConstant Composition Varying Composition
High mineral content Low mineral content
Low turbidity High turbidity
Low or no colour Colour
May be bacteriologically safe Microorganisms present
No dissolved Oxygen Dissolved oxygen
High hardness Low hardness
H2S, Fe, Mn Tastes and odours
Possible chemical toxicity Possible chemical toxicity
Water Quality Contd...� Water quality managers are concerned with controlling
pollution from human activity so as to ensure that thewater is suitable for its intended uses.
� Water quality management is also the science of knowinghow much waste is too much for a particular water body.how much waste is too much for a particular water body.
� To know how much waste can be tolerated(the technicalterm is assimilated) by a water body, water qualitymanagers must know the type of pollutants discharged andthe manner in which they affect water quality.
� They must also know how water quality is affected bynatural factors such as the mineral heritage of thewatershed, the geometry of the terrain, and the climate ofthe region.
Water pollutants and their sources� The wide range of pollutants discharged to surface waters
that is the source of pollutants can be grouped into twoclasses.
Point Sources:
� Domestic sewage and industrial wastes act as point� Domestic sewage and industrial wastes act as pointsources because they are generally collected by a networkof pipes or channels and conveyed to a single point ofdischarge into the receiving water.
� Domestic sewage consists of wastes from homes, schools,office buildings, and stores.
� The term municipal sewage includes domestic sewagealong with any industrial wastes that are permitted to bedischarged into the sanitary sewers.
Point sources� Point source pollution comes from a defined, specific
source such as a discharge pipe from a factory, amunicipal sewage treatment plant, or a powergenerating station.generating station.
� In general, point source pollution can be reduced oreliminated through waste minimization and properwastewater treatment prior to discharge to a naturalwater body.
Point sources
Point Sources
Non point sources� Urban and agricultural runoff are characterized by
multiple discharge points and are called non point sources.
� Much of non point source pollution occurs duringrainstorms or spring snowmelts, resulting in large flowrainstorms or spring snowmelts, resulting in large flowrates that make treatment even more difficult.
� Urban storm water runoff (including that from streets,parking lots, golf courses and lawns) can transportpollutants such as nitrogen and phosphorous fromfertilizers, herbicides applied to lawns and golf courses, oil,greases, ehylene glycol (used in antifreeze), and cut grassand other organic debris.
Non Point Sources