Water Quality Standards & Contamination: Physical, Chemical, & Bacteriological Analysis

1. WELCOME

2. PHYSICAL, CHEMICAL & BACTERIOLOGICAL CONTAMINATION OF WATER AND WATER QUALITY STANDARDS

3. Distribution of water on earth • Ocean and sea - 97% • Snow and ice caps - 2% • Rivers,lakes, Ground water - 1%

4. UNIVERSAL SOLVENT • QUALITY • DEMERIT • 45 LAC WELLS AND 50 LAC SEPTIC TANKS ( ?)

5. contamination • Geological • Human activities . Organic waste Industrial waste

6. Aquifiers

7. Safe drinking water Free from pathogenic organisms Clear Not saline Free from offensive taste or smell Free from compounds that may have adverse effect on human health Free from chemicals that cause corrosion of water supply systems

8. WATER QUALITY PARAMETERS • Physical parameters • Chemical • Bacteriological

9. Colour • May be due to the Presence of organic matter,metals(iron, manganese) or highly coloured industrial waste • Aesthetically displeasing • Disirable that drinking water be colourless • Disirable limit, 5 Hazen unit • Permissible limit 25 Hazen Unit

10. Taste and Odour • Mainly due to organic substances, ,Biological activity, industrial pollution • Taste buds in the oral cavity specially detect inorganic compounds of metals like magnesium, calcium, sodium, copper, iron and zinc • Water should be free from objectionable taste and odour.

11. Turbidity • Caused by suspended matter • High level turbidity shield and protect bacteria from the action of disinfecting agents • Desirable limit-5NTU should be below 1 NTU when disinfection is practiced Permissible limit-10NTU

12. Solids Total Solids Residue on evaporation at 103oC TS = (Wds – Wd)/V Where: Wds = weight of dish plus solids after evaporation Wd = weight of dish alone V = volume of sample

13. Total Solids can be divided into two fractions: Suspended Solids Suspended solids are the solids that can not pass through a glass fiber filter with a 0.45 micron pore opening Dissolved Solids Dissolved solids are the solids that can pass through a glass fiber filter with a 0.45 micro pore size

14. Suspended solids SS = (Fdf – Fd)/ V Where: Fdf = weight of the Filter plus dry filtered solids Fd = weight of the clean, dry filter V = volume of sample

15. Volatile and Fixed Solids Volatile solids are the solids that are volatilized at 600oC Fixed solids are the solids that remain after heating to 600oC Generally the volatile solids are considered to be the organic fraction of the solids. Volatile Solids = Total Solids – Fixed Solids

16. Solids: significance • TDS: used as a measure of inorganic salt content in drinking waters and natural waters • TSS: used to assess clarifier performance • VSS: used to estimate bacterial populations in wastewater treatment systems

17. Solids Analysis

18. pH • It is the measure of hydrogen ion concentration • Neutral water pH-7 • Acidic water has pH below 7 • Basic water has pH above 7 • Disirable limit 6.5-8.5 Beyond this limit the water will affect the mucous membrane and water supply system

19. Acidic Industries Sugar - 5 – 6 Distillery 3 - 4 Electro- Plating unit 2.5-4 Pickle 2 - 3 Basic Paper 8 – 10 Textile 8.5-11 Fertiliser 6.5- 9 Oil Refine- ries 6.5-9.5 Substances that change pH of water

21. HARDNESS • Capacity of water for reducing and destroying the lather of soap • It is total concentration of calcium and magnesium ions • Temporary hardness – Bicarbonates of Calcium and Magnesium • Permanent hardness – Sulphates, chlorides and nitrates of calcium and magnesium

22. Hardness – contd… • 0 – 50 mg/l - soft • 50 – 150 mg/l - moderately hard • 150 – 300 mg/l - hard • 300 above - very hard • Surface water is softer than ground water • Causes encrustations in water supply structures

23. ALKALINITY • Capacity to nutralise acid • Presence of carbonates, bi-carbonates and hydroxide compounds of Ca, Mg, Na and K • Alkalinity = hardness, Ca and Mg salts • Alkalinity > hardness - presence of basic salts, Na, K along with Ca and Mg • Alkalinity < hardness – neutral salts of Ca & Mg present

24. IRON • One of the earth’s most plentiful resource • High iron causes brown or yellow staining of laundry, household fixtures • Metalic taste, offensive odour, poor tasting coffee • Cause iron bacteria • Acceptable limit – 0.3 mg / l

25. CHLORIDE • Causes • Dissolution of salt deposit • Discharge of effluents • Intrusion of sea water • Not harmful to human beings • Regarding irrigation – most troublesome anion • Acceptable limit - 250 mg/l

26. NITRATE • Increasing level of nitrate is due to • Agricultural fertilizers, manure,animal dung, nitrogenous material ,sewage pollution • (blue baby diseases to infants) • Maximum permissible limit 45 mg / l

27. FLOURIDE • Occurs naturally • Long term consumption above permissible level can cause – • dental flurosis (molting of teeth) • Skeletal flurosis • Acceptable limit – 1 mg / l • Maximum permissible limit – 1.5 mg / l • Remedy – 1) Deflouridation 2) Mixing Fluride free water 3) Intake of vitamin C,D, calcium,antioxidants

28. FLOURIDE CAUSES Three types of Fluorosis 1. Dental Fluorosis 2. Skeletal Fluorosis 3. Non-skeletal Fluorosis

29. ARSENIC • Occur in ground water from arseniferous belt • Industrial waste, agricultural insecticide • High arsenic causes 1) various type of dermatological lesions, muscular weakness, paralysis of lower limbs, can also cause skin and lung cancer • Acceptable limit – 0.05 mg / l

30. Heavy Metals • Present as mineral in soil and rocks of earth • Human activities Battery – Lead & Nickel Textile - Copper Photography – Silver Steel production – Iron

31. Pesticides • Cancer • Birth defects • Blood disorder • Nervous disorder • Genetic damage

32. Essential bacteriological Standards

33. RESIDUAL CHLORINE Chlorine added to water forms hypochlorite ions and hypochlorite acids Chlorine demand – Quantity required for killing micro organisms and reacting with ammonia, organic compounds etc. Free residual chlorine – To take care of post contamination Desirable – 0.2 mg / liter

34. Common problems contd

35. Common problems

36. Measures of Water Quality Some of the Most basic and Important Measures Dissolved Oxygen Biochemical Oxygen Demand Solids Nitrogen Bacteriological

37. Dissolved Oxygen (DO) Typically Measured by DO probe and Meter Electrochemical Half Cell Reaction

38. Biochemical Oxygen Demand (BOD) Amount of oxygen used by microorganisms to decompose organic matter in a water Theoretical BOD can be determined by balancing a chemical equation in which all organic matter is converted to CO2 Calculate the theoretical oxygen demand of 1.67 x 10-3 moles of glucose (C6H12O6): C6H12O6 + O2 CO2 + H2O general, unbalanced eqn C6H12O6 + 6 O2 6 CO2 + 6 H2O 1.67x 10-3moles glucose/L x 6 moles O2/ mole glucose x 32 g O2/mole O2 = 0.321 g O2/L = 321 mg O2/L

39. BOD Test Dark 20oC Time Standard – 5 days Ultimate

40. BOD = I - F I = Initial DO F = Final DO If all the DO is used up the test is invalid, as in B above To get a valid test dilute the sample, as in C above. In this case the sample was diluted by 1:10. The BOD can then be calculated by: BOD = (I – F) D D = dilution as a fraction D = volume of bottle/(volume of bottle – volume of dilution water) BOD = (8 – 4) 10 = 40 mg/L

41. For the BOD test to work microorganisms have to be present. Sometimes they are not naturally present in a sample so we have to add them. This is called “seeding” a sample If seed is added you may also be adding some BOD. We have to account for this in the BOD calculation: BOD = [(I – F) – (I’ – F’)(X/Y)]D Where: I’ = initial DO a bottle with only dilution water and seed F’ = final DO of bottle with only dilution water and seed X = amount of seeded dilution water in sample bottle, ml Y = amount of seeded dilution water in bottle with only seeded dilution water

42. Example Calculate the BOD5 of a sample under the following conditions. Seeded dilution water at 20oC was saturated with DO initially. After 5 days a BOD bottle with only seeded dilution water had a DO of 8 mg/L. The sample was diluted 1:30 with seeded dilution water. The sample was saturated with DO at 20oC initially. After five days the DO of the sample was 2 mg/L. Since a BOD bottle is 300 ml a 1:30 dilution would have 10 ml sample and 290 ml seeded dilution water. From the table, at 20oC, DOsat = 9.07 mg/L BOD5 = [(9.07 – 2) – (9.07 – 8)(290/300)] 30 = 174 mg/L

43. Chemical Oxygen Demand Same principle as BOD but different execution. Rather than biologically decompose/oxidize organic waste, we chemically decompose/oxidize organic waste.

44. COD: A chemical test The chemical oxygen demand (COD) of a waste is measured in terms of the amount of potassium dichromate (K2Cr2O7) reduced by the sample during 2 hr of reflux in a medium of boiling, 50% H2SO4 and in the presence of a Ag2SO4 catalyst.

45. COD errors The most common COD errors are due to oxidation of inorganic species. Dichromate is a powerful oxidant – it will oxidize not only almost all organics but many metals and non-metal ions: 6 Fe2+ + Cr2O72- + 14 H+ → Fe3+ + 2 Cr3+ + 7 H2O 6 Cl- + Cr2O72- + 14 H+→ 3 Cl2 + 2 Cr3+ + 7 H2O

46. COD errors As a result, contaminated water will tend to test higher than it should based strictly on the organic contamination.

47. COD vs. BOD They purport to measure the same thing – but they will never agree. Biggest error in BOD? BOD tends to err on the low side due to humus (“inedible” organic waste). Biggest error in COD? COD tends to err on the high side due to oxidation of inorganic species.

48. Using COD COD is again a relative measure: higher COD = dirtier water. COD can be used with BOD – they are not a replacement for each other. COD must be viewed in context of all other tests.

49. Comparing all of our “oxygens” Dissolved oxygen () – amount of actual oxygen dissolved in a water sample. Higher number = purer water BOD5 – Actual amount of dissolved oxygen metabolised over 5 days. Higher number = dirtier BOD – Extrapolated amount of theoretical oxygen that would be needed to completely metabolise organic waste. Higher number = dirtier COD – Actual amount of oxygen required to completely oxidize organic waste CHEMICALLY. Higher number = dirtier.

50. Thank you