Water Pollution, Sources & Hazards, PDF

Water:- Pollution, Sources & hazards, Water borne diseases, Water Purification & Standards of Potable water Dr. Mohammad Suhail Khan Associate Professor Department of Public Health King Khalid University, Abha ,KSA INTRODUCTION • Much of the ill-health which affects humanity, especially in the de...

Water:- Pollution, Sources & hazards, Water borne diseases, Water Purification & Standards of Potable water Dr. Mohammad Suhail Khan Associate Professor Department of Public Health King Khalid University, Abha ,KSA INTRODUCTION • Much of the ill-health which affects humanity, especially in the developing countries can be traced to lack of safe and wholesome water supply. • Water that is easily accessible, adequate in quantity, free from contamination, safe and readily available throughout the year. • In 1980, the United Nations General Assembly launched the International Drinking Water Supply and Sanitation Decade, 1981-1990-the aim being to provide all people with adequate supplies of safe water and sanitation by 1990. • In 1981, the 34th World Health Assembly in a resolution emphasized that safe drinking water is a basic element of “primary health care” which is the key to the attainment of “health for all by the year 2000 AD”. SAFE AND WHOLESOME WATER a. Free from pathogenic agents b. Free from harmful chemical substances c. Pleasant to the taste i.e., free from colour and odour d. Usable for domestic purposes. WATER REQUIREMENT 1. 2. 3. Drinking water have been estimated at about 2 liters per head per day. The consumption of water , however, depends upon climate conditions, standard of living and habits of people. A daily supply of 150-200 liters per capita is considered as an adequate supply to meet the needs for all urban domestic purposes. USES OF WATER: 1. Domestic use: for drinking, cooking, washing, and bathing etc. 2. Public purposes: like swimming pools, public fountains and ornamental ponds, fire protection and public parks etc. 3. Industrial purposes: for processing and cooling etc. 4. Agricultural purposes: irrigation. 5. Power production from hydropower and steam power. 6. Carrying away waste from all manner of establishments and institutions. SOURCES OF WATER SUPPLY ➢Rain ➢ Surface water● Impounding reservoirs ● Rivers and streams ● Tanks, ponds & lakes ➢Ground water ● Shallow wells ● Deep wells ● Springs RAIN Prime source CHARACTERISTICS : • Purest water in nature. • Physically it is clear, bright and sparkling. • Chemically it is very soft water containing only traces of dissolved solids. Being soft, it has a corrosive action on lead pipes. SURFACE WATER ➢Originates from rain water. ➢Prone to contamination from human and animal sources. 1. 2. 3. Impounding reservoirs Rivers and streams Tanks, ponds and lakes 1. IMPOUNDING RESERVOIRS ● These are artificial lakes constructed usually of earthwork or which large quantities of surface water is stored. masonry in ●Clear, palatable and ranks next to rain water in purity ●Dams built across rivers and mountain streams also provide large reserves of surface water. ●The area draining into the reservoir is called “CATCHMENT AREA”. ●One disadvantage of storing water for long periods in reservoirs is the growth of algae and other microscopic organisms, which impart bad tastes and odors to water. 2. RIVERS •Many rivers furnish a dependable supply of water. •The chief drawback of river water is that it is always grossly polluted and is quite unfit for drinking without treatment. CHARACTERISTICS: Turbid during rainy season; it may be clear in other seasons. The bacterial count, including the human intestinal organisms may be very high. IMPURITIES: The impurities of river water are derived from surface washing, sewage and sullage water, industrial and trade waste and drainage from agricultural areas. SELF PEURIFICATION: By natural forces of purification such as Dilution, sedimentation ,aeration, oxidation , sunlight , plant & animal life but not sufficient. 3. TANKS • Large excavations in which surface water is stored. • They are an important source of water supply in • some developing countries villages. • IMPURITIES: Also used for washing of clothes, cattle, humans, cooking pots; children use it for swimming and there may be regular defecation around the edges which will be washed into the tank at the next rains. Tanks are thus subjected to unlimited possibilities of contamination and are highly dangerous, as a source of drinking water. SEA WATER • It contains 3.5 % of salts in solution. • Off -shore waters of the oceans and seas have a salt concentration of 30 to 36 gm/ltr of dissolved solids including 19 gm/ltr of chloride, 10.6 gm/ltr of sodium and 1,270 mg/ltr of magnesium. • Desalting and demineralization process involves heavy expenditure. • It is adopted in places where sea water is the only source available. C. GROUND WATER • Rain water percolating into ground constitutes ground water. • It is the cheapest and most practical means of providing water to small communities. • It is superior to surface water , because the ground itself provides an effective filtering medium. • 1. 2. WEL LS Technically, wells are of two kinds – Shallow wells Deep wells. SPRIN GS • When ground water comes to the surface and flows freely under natural pressure, it is called a “spring”. • Springs may be of two types – shallow springs deep springs. • Shallow springs dry up quickly during summer months, whereas deep springs do not show seasonal fluctuations in the flow of water.