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Module 41 Water Chemistry & Microbiology On completion of this module you should be able to: Have some knowledge of the chemical and physical properties.

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Presentation on theme: "Module 41 Water Chemistry & Microbiology On completion of this module you should be able to: Have some knowledge of the chemical and physical properties."— Presentation transcript:

1 Module 41 Water Chemistry & Microbiology On completion of this module you should be able to: Have some knowledge of the chemical and physical properties of water Have an understanding of water microbiology Be aware of some disease causing microorganisms Be able to describe the microbiological standards of drinking water

2 Module 42 Typical Raw Water

3 Module 43 Drinking Water Quality Water for human consumption must be free from pathogenic organisms and from chemicals hazardous to health Water must be aesthetically acceptable (odour, colour, taste), and also non-corrosive or scale forming Water should conform to some acceptable guidelines e.g. WHO, NHMRC

4 Module 44 Water Quality Characterisation We can characterise water quality in terms of the following Chemical Physical Radiological Bacteriological

5 Module 45 Chemical Properties of Water Dependent on the composition of solutes present Solutes are natural or introduced anions and cations in water, which may contribute to taste, odour and hardness Concentrations of solutes that are injurious to to health Solutes are largely inorganic but some may be organic

6 Module 46 Some Health related Chemical Characteristics

7 Module 47 pH of water pH = -log 10 [H 3 O] Buffering – ionic forms of CO 2 that offer resistance to pH change Diurnal changes in raw water may affect pH values 1 M HCl Pure water 1 M NaOH Gastric juice seawater Household ammonia

8 Module 48 Effects of buffering in water Pure water Carbonate in water Carbonic acid Well water

9 Module 49 Physical Properties of Water Colour Turbidity or total suspended solids (TSS) Total dissolved solids (TDS) which may be related to hardness Odour and taste Temperature

10 Module 410 Radiological Radioactivity is the energy released from the breakdown of radionuclides Naturally occurring radioactive species in drinking water sources Contamination from concentration of natural levels such as mining and processing of minerals Artificial radionuclides which may enter drinking water supplies from medical and industrial use of radioactive materials

11 Module 411 Water Microbiology Of living organisms (apart from animals and plants) there is a third kingdom of Protisa Eucaryotic cells ( micron) Procaryotic cells ( micron) Viruses ( nm)

12 Module 412 Procaryotic Cells Bacteria, blue green algae (cyano-bacteria) Small size with simple organisation Nuclear region - single DNA molecule not separated from cytoplasm by any defined structure Cytoplasm - a site of protein synthesis (RNA), a colloidal suspension of proteins, carbohydrates and complex organic compounds Cytoplasm membrane with enzymes for transport of food into cells and removal of wastes Cell wall to maintain rigidity and shape of cell

13 Module 413 A Bacterium Cell

14 Module 414 Bacteria Cells

15 Module 415 Bacteria Some are pathogenic. Majority assist in breaking down matter. The bacterial cell is a chemical machine that transforms energy through metabolism Catabolism where larger molecules are broken down with the release of energy Anabolism a biosynthesis of new molecules from simple nutrients

16 Module 416 Bacteria may be classified as Heterotrophic requiring an external organic source for energy and carbon Autotrophic that utilises inorganic compounds for energy and uses CO 2 as a carbon source Aerobic, anaerobic and facultative in relation with O 2

17 Module 417 Eucaryotic Cells Examples are algae, fungi, protozoa More complex than procaryotic cells Well defined nucleus with a nucleus membrane Membrane bound organelles that perform various tasks Unicellular or multicellular

18 Module 418 Algae Resembles plants but without roots, stems, leaves Photosynthetic, autotrophic microorganism Important role of recycling nutrients in the aquatic food chain Contributes to clogging of filters, odour & taste in water, and eutrophication

19 Module 419 Fungi (yeast, mould, mushroom) The ability of fungi to survive under low pH and nitrogen limiting conditions, and distinctive degradative ability makes them important in wastewater treatment Non-photosynthetic Multi/or unicelluar and immotile Reproduce sexually or asexually Yeasts are unicellular, capable of aerobic and anaerobic growth Moulds are strict aerobes

20 Module 420 Protozoa Non-photosynthetic Single cell eucaryote that obtain energy from metabolising organic matter by feeding on bacteria, fungi and algae Important role in the secondary settling of the wastewater treatment process Some are a concern in drinking water e.g. cryptosporidium, giardia

21 Module 421 Protozoa The discovery of the cryptosporidium parasite in water supplies in Glasgow (Aug 2002) comes a matter of months after an outbreak struck the north east of Scotland. The latest alert has affected about 140,000 people in Glasgow after the infection, which can cause severe diarrhoea, was detected in the Mugdock Reservoir in Milngavie. Those in the affected areas have been urged to boil water before drinking it. Cryptosporidium is commonly spread by animals However, Scottish Water said it was safe to use for washing clothes and dishes and for bathing - although not for bathing babies.

22 Module 422 Viruses Do not have the ability to reproduce themselves but replicated only within a host cell Small structures of non-living compounds Composed of 2 kinds of macromolecules i.e protein and DNA or RNA Acellular Obligate intracellular parasites

23 Module 423 Waterborne Diseases and Agents Dependent on the causal agent Bacterial e.g. cholera, typhoid fever Viral e.g. hepatitis A, diarrhoea Protozoal e.g. amoebic dysentry, giardiasis Helminths e.g. schistosomiasis

24 Module 424 Indicator Microorganisms for Drinking Water Coliform group of microorganisms is present in large numbers in animal and human excreta. Why is there a need for such indicators? Pathogenic microorganisms are small in numbers Routine testing is not practicable and expensive Involves skilled labour and specialist equipment Specific tests may not be available

25 Module 425 Indicator Microorganisms Properties Microbial indicators are E.coli and the coliform group Always present when pathogens of like origin are present Present in large numbers, >> pathogens Easy and quick to detect Equal or greater survival time than pathogens Absent from unpolluted waters Similar sensitivity to disinfection as pathogens

26 Module 426 Bacterial Standards of Drinking Water 98% of samples in any one year should not have any E.coli in 100 mL 95% of samples in any one year should not have any coliform organisms in 100 mL Max 10 coliform organisms per 100 mL in any one sample No coliform organism in 100 mL of any two consecutive samples

27 Module 427 Objectives of Water Sampling Ensure aesthetic qualities, adequate residual chlorine and free from harmful chemicals Bacterial qualities of raw and treated water are acceptable Sources of pollution or potential contamination are known

28 Module 428 Types of Sampling Related to population size Residual chlorine concentration Simple bacteriological test Simple chemical analysis Full chemical and bacteriological analysis

29 Module 429 Frequency of Sampling Related to population size Population servedMinimum number of samples Above samples per week, plus 1 additional sample per month for each above – sample per week, plus 1 additional sample per month for each above sample per week Under 1 000Minimum samples for small water supplies

30 Module 430 END OF MODULE 4


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