Environmental Engineering-I

Transcription

1 Environmental Engineering-I Prof. Dr. Muhammad Zulfiqar Ali Khan Engr. Muhammad Aboubakar Farooq Department of Civil Engineering The University of Lahore 1

2 Water Quality Water Impurities and their Health Significance Water Quality Guidelines / Standards (WHO ) Water Quality Monitoring. 2

3 Water Quality Quality: It is defined as the degree of excellence, a measure of fitness of use. Drinking Water Quality: It refers to degree of cleanliness and wholesomeness of water. Drinking quality is judged in terms of chemical, physical and bacteriological contents of water. Potable Water: It is the water which is safe to drink, pleasant to taste and usable for domestic purposes. Thus it has aesthetic appearance and is free from harmful chemicals and disease causing bacteria. 3

4 Polluted/Contaminated Water: Water containing pathogenic microorganisms, harmful chemicals, or sewage is termed as polluted or contaminated water. Degree of Cleanliness: How much water is sparkling. Wholesomeness: Water Quality Things which produce good effect on human Health. 4

5 Water Quality Parameters The analysis of water is undertaken in order to establish the quality of water. Drinking water quality is mostly judged in terms of: Physical Parameters Chemical Parameters Bacteriological Parameters Radiological Parameters 5

6 1. Physical Parameters: 1. Taste and Odour: Taste may be sweet, bitter, salty as well as irritating hot and cold. Assessing Taste may vary from person to person. The principle involved in measuring odour is that since small concentration of odoriferous substances cannot be detected accurately and vary from person to person. 6

7 1. Physical Parameters: 1. Taste and Odour: (contd ) The value given to a particular odour conc. is called odour intensity. This test is made by inhaling through an osmoscope in a flask containing diluted water. May be caused in water by organic compounds, inorganic salts or dissolved gases. Drinking water should be free from objectionable taste and odour. 7

8 1. Physical Parameters: 2. Colour: Colour in drinking water may be caused by vegetable dyes or presence of iron and manganese. Its presence is aesthetically objectionable. The maximum permissible color for domestic water is 20 ppm, on platnium cobalt scale. 8

9 1. Physical Parameters: 3. Turbidity: Turbidity is due to the presence of colloidal solids in water sample. Turbid waters are of cloudy appearance which makes them aesthetically unattractive. In past This was expressed by the amount of suspended matter in Parts per million (ppm or mg/l) in water as ascertained by optical observations. 9

10 1. Physical Parameters: 3. Turbidity: (contd ) The device used in today s labs is nephelometric meter. Turbidity is read as nephelometric turbidity units (NTU). According to WHO guidelines, acceptable limits of turbidity is <5 NTU. 10

11 1. Physical Parameters: 4. Conductivity: Conductivity is a measure of electrolyte content of water and is related to dissolved mineral salts in the water. 5. Total Dissolved Solids: TDS in drinking water impart taste and consist mainly of inorganic salts and small amount of organic matter. TDS present in water indicate solubility of water for domestic use. Desirable TDS content : <500mg/L. 11

12 2. Chemical Parameters: 1. Alkalinity: It is the capacity of a water sample to neutralize strong acids. Alkalinity measurements are used in the determination of coagulant dose, carbonate hardness and chlorine dose. Alkalinity is expressed in terms of mg/l of CaCO 3. 12

13 2. Chemical Parameters: 2. Acidity: It is the capacity of a water sample to neutralize strong basis. Acidity in water is generally caused due to dissolution of CO 2. H 2 O + CO 2 H 2 CO 3 Acidity is measured in terms of CaCO 3 needed to neutralize the carbonic acid. Acidity is expressed in terms of mg/l of CaCO 3. 13

14 2. Chemical Parameters: 3. ph: It is expressed as the common logarithm of the reciprocal of the Hydrogen ion [H + ] concentration. i.e. ph = log [ 1 H + ] ph test determines the strength of an acid or base while the chemical test for acidity or alkalinity determines the amount of acid or base. 14

15 2. Chemical Parameters: 4. Hardness: It is property of preventing lather formation with soap. Hardness also produces scale in hot water systems. Hardness is caused by divalent metallic ions in water which react with soap to form precipitate. These ions are most commonly associated with bicarbonates, sulphates and chloride in water. 15

16 2. Chemical Parameters: 5. Metals and Others: Arsenic Chromium Cyanide Flouride Lead Mercury Nitrates DDT Carcinogenic, Skin Cancer. Carcinogenic, Skin allergy, impairs kidneys. Affects thyroid and nervous system. Dental Caries and fluorosis. General Toxicant, Toxic to nervous system, upset stomach. Impairs kidney, affects brain. Causes methemoglobinemia in infants. Carcinogen to animals, toxic to human. 16

17 3. Bacteriological Parameters: Coliforms: This group consists of: Aerobactor Aerogenes: These are normally found in soil, plants, grains, and to some extent in the faeces of the man and animal. Escherichia Coli (E-Coli): These are normally found in the intestinal tract of man and animal. They are excreted with faeces. 17

18 3. Bacteriological Parameters: Coliforms (E-Coli) are considered nonpathogenic but can cause infection of genito-urinary tract. The term Faecal Coliforms refer to all those coliforms which are present in faeces. These mostly consist of E.Coli, but may contain Aerobector Aerogenes and other variety of coliforms. They are also named as Thermotolerant Coliform Bacteria. 18

19 4. Radiological Parameters: Alpha and beta activity. Radio active material concentrations in drinking water are largely due to naturally occurring radionuclides in the uranium and thorium decay series. These radionuclides are present in soil. Radioactivity is measured by Geiger in term of 1 Bq/L. 19