1. ENG421 (4ab) – Water Quality Management
Week 1 revision
Water Pollution
Water Quality Management
- water to treatment plant
in rivers
in lakes
in groundwater systems
- water leaving treatment plant
Water Treatment Technologies
Operational Goals
Water Treatment Plant
- for surface water
- for groundwater
- for residual management

2. Water Quality – Week 1 revision (1 of 7)
Australian Drinking Water Guidelines (ADWG)
Microbial Quality
Physical Quality
Chemical Quality
Radiological Quality

3. Water Quality – Week 1 revision (2 of 7)
Australian Drinking Water Guidelines (ADWG)
- greatest risks is pathogenic microorganisms
- drinking water system must have multiple barriers
- changes in water quality, flow or environmental conditions consider that drinking water might become contaminated
- system operators must respond quickly to adverse monitoring signals
- system operators must maintain a personal sense of responsibility and dedication to providing consumers with safe water, never ignore a consumer complaint
- use risk management approach

4. Water Quality – Week 1 revision (3 of 7)
describes water in terms of its characteristics
Water Characteristics
temperature
concentrations of various particles
concentrations of dissolved materials
parameters
turbidity pH
colour
conductivity
biological oxygen demand
UV absorbance
Water Quality Profile
a particular combination, or set, of characteristics

5. Water Quality – Week 1 revision (4 of 7)
Microbial Quality
most common drinking water health risk
contamination by human or animal excreta and the microorganisms contained in faeces
recent contamination may cause communicable enteric diseases (diseases of the gut)
drinking contaminated water or using it in food preparation may cause new cases of infection
greatest risk of infection to :
infants and young children
people whose immune system is suppressed
the sick
the elderly
Pathogenic (disease-causing) organisms of concern include :
bacteria
viruses
protozoa
diseases caused vary in severity
mild gastroenteritis
severe and sometimes fatal diarrhoea, dysentery, hepatitis, cholera or typhoid fever

6. Water Quality – Week 1 revision (5 of 7)
Physical Quality
appearance, taste, odour, and ‘feel’ of water determine what people experience (subjective) when they drink or use water and how they rate its quality
other physical characteristics can suggest whether corrosion and encrustation are likely to be significant problems in pipes or fittings
measurable characteristics :
• true colour (i.e. the colour that remains after any suspended particles have been removed)
• turbidity (the cloudiness caused by fine suspended matter in the water)
• hardness (the reduced ability to get a lather using soap)
• total dissolved solids (TDS)
• pH
• temperature
• taste and odour
• dissolved oxygen

7. Water Quality – Week 1 revision (6 of 7)
Chemical Quality
a number of chemicals are considered :
organic
inorganic
some pesticides
issues include :
health concerns
toxic to humans
suspected of causing cancer
affect the aesthetic quality of water

8. Water Quality – Week 1 revision (7 of 7)
Radiological Quality
Sources of radiation in the environment and in drinking water :
- radioactive materials occur naturally in the environment
(e.g. uranium, thorium and potassium)
- some radioactive compounds arise from human activities
(e.g. from medical or industrial uses of radioactivity)
- some natural sources of radiation are concentrated by mining
and other industrial activities.
the largest proportion of human exposure to radiation comes from natural sources
- cosmic radiation
- ingestion or inhalation of radioactive materials.
a very low proportion of the total human exposure comes from drinking water
Radiological contamination of drinking water can result from:
- naturally occurring concentrations of radioactive species
(e.g. radionuclides of the thorium and uranium series in drinking water sources)
- technological processes involving naturally radioactive materials
(e.g. the mining and processing of mineral sands or phosphate fertiliser production)
- manufactured radionuclides, which might enter drinking water supplies from the medical
and industrial use of radioactive materials

9. Water Pollution (1 of 3) Pollutants released into environment as :
gases
dissolved substances
particulate matter
liquid droplets
solids
pathways of pollutants into water

10. Water Pollution (2 of 3) Sources of Pollutants : Point Source
pollution comes from a single outlet
may be collected, treated or controlled
major point sources polluting water
collection and discharge of
domestic waste
industrial waste
some agricultural activities (e.g. animal husbandry)
time variability of pollutant release into water
permanent or continuous
e.g. domestic sewers, industrial wastes
periodic
e.g. wastes from small holiday resort or food processing
occasional
e.g. some industrial wastes
accidental
e.g. tank failure, truck or train accidents, fires
Diffuse (non-point) Sources
difficult to collect and treat
e.g. most agricultural activities (pesticide spraying, fertiliser application)
agricultural runoff, stormwater runoff, automobile exhaust

11. Water Pollution (3 of 3)
Sources of Pollutants :

12. Water Quality Management
Manage quality of water leaving source to treatment plant
Manage quality of water leaving treatment plant to supply system (customers)
Quality of water going to water treatment plant from rivers, lakes and groundwater is influenced by intended use of those water bodies
(e.g. water supply only, dilution of domestic and industrial wastes)
Water Quality Management involves
managing and controlling pollution from human activity
so that water remains suitable for intended use
e.g. polluted river may be unsuitable for irrigation
or human consumption or recreation
Previously, water bodies used as cheap waste disposal option
Now, pollutant discharges to water bodies minimised or eliminated

13. Water Quality Management in Rivers (1 of 3)
Rivers and streams may receive
pollutants
waste water
treated effluent for dilution
Rivers and streams rely on
natural self-purification to assimilate wastes
and restore river/stream quality
Capacity to recover from pollutants determined by
characteristics of river
volume and flow rate of river
river depth
nature of river bed
surrounding vegetation
meteorological events (e.g. rainfall in catchment area)

14. Water Quality Management in Rivers (2 of 3)
River Water Quality Management
control discharges into river
keep river water quality at level where it can recover
compare river water quality with natural background level (quantitative)
Pollutants into rivers
toxic substances (kill flora and fauna)
oxygen-demanding wastes
organic and inorganic
depletes dissolved oxygen in river
danger to flora and fauna if oxygen concentration
falls below critical level (minimum required)
may predict oxygen depletion
know amount and strength of waste discharged to river
oxygen continuously replenished from atmosphere
aquatic fauna consume oxygen
aquatic flora impact on oxygen
during daylight photosynthesis produces oxygen
plants die, settle to bottom (benthic layer), decompose
compare relative rates of computing users of oxygen

15. Water Quality Management in Rivers (3 of 3)
Pollutants into rivers (cont)
nutrients
contribute to deteriorating water quality (cause excessive plant growth)
(e.g. algal blooms in inland rivers in Australia)
warm temperatures and slow moving rivers enhance algal bloom
fertiliser contains :
nitrogen
high concentration of ammonium-nitrogen is toxic to fish
low concentration of ammonium-nitrogen and nitrate-nitrogen
provide nutrients for excessive growth of algae
phosphorus
supports growth of algae
decomposition of dead algae creates oxygen demanding organic material
Control of nutrient caused water quality problems
remove nitrogen and phosphorus before discharge to river
do this at the source (difficult for non-point sources)

16. Water Quality Management in Lakes
Most significant pollutant is phosphorus
Oxygen demanding chemicals and toxic substances may be significant
Water in lakes becomes stratified over summer
warm layer of water at the top
cooler layer of water at the bottom
layers overturn in winter
when top layer gets colder than bottom layer
these physical processes interact with phosphorus
impact on lake water quality
Productivity (eutrophication) of lake
natural process (may be influenced by human activities)
measure of ability to support food chain (amount of algal growth)
requires sunlight and nutrients (Loch Ness monster in COR111)
too much phosphorus
→ too much algae
→ water becomes highly turbid (not clear, muddy in appearance)
→ algae die, settle to bottom, decompose
→ depleted dissolved oxygen levels
Control via
reduce phosphorus input to lake
dredge bottom of lake to remove phosphorus rich sediments

17. Water Quality Management in Groundwater Systems (1 of 3)
Natural groundwater contains chemical species and gases in solution
Ionic species often from surrounding soil and rock
Soil bacteria may be in water
Human activity also contributes to contaminants in groundwater
Control of contamination of groundwater
determine source of pollutant
cleanup and control source via :
containment
removal
treatment

18. Water Quality Management in Groundwater Systems (2 of 3)
Human activities contaminating groundwater

19. Water Quality Management in Groundwater Systems (3 of 3)
Human activities contaminating groundwater (cont)

20. Water Supply Sources
Knowing where the water comes from, its quality, and where it is going determines treatment required

21. Constituents in Water
Constituents found in surface water and groundwater may need to be removed, inactivated or modified

22. General Water Treatment Technologies
Treatment technologies (unit operations and processes) used determined by what needs to be removed, inactivated or modified

23. Unit Operations and Processes used to treat Water (1 of 7)
Physical Unit Operations

24. Unit Operations and Processes used to treat Water (2 of 7)
Physical Unit Operations (cont)

25. Unit Operations and Processes used to treat Water (3 of 7)
Physical Unit Operations (cont)

26. Unit Operations and Processes used to treat Water (4 of 7)
Physical Unit Operations (cont)

27. Unit Operations and Processes used to treat Water (5 of 7)
Chemical Unit Operations (cont)

28. Unit Operations and Processes used to treat Water (6 of 7)
Chemical Unit Operations (cont)

29. Unit Operations and Processes used to treat Water (7 of 7)
Biological Unit Operations (cont)

30. Treatment Processes for Specific Constituents (1 of 10)
Physical Parameters
a inline filtration is coagulation followed by filtration (aka contact filtration)
b direct filtration is coagulation followed by flocculation and filtration
c conventional treatment is coagulation, flocculation, sedimentation, and filtration

31. Treatment Processes for Specific Constituents (2 of 10)
Physical Parameters (cont)

32. Treatment Processes for Specific Constituents (3 of 10)
Inorganic Chemical Parameters

33. Treatment Processes for Specific Constituents (4 of 10)
Inorganic Chemical Parameters (cont)

34. Treatment Processes for Specific Constituents (5 of 10)
Inorganic Chemical Parameters (cont)

35. Treatment Processes for Specific Constituents (6 of 10)
Organic Chemical Constituents

36. Treatment Processes for Specific Constituents (7 of 10)
Radionuclides

37. Treatment Processes for Specific Constituents (8 of 10)
Microbial Parameters

38. Treatment Processes for Specific Constituents (9 of 10)
Aesthetic Parameters

39. Treatment Processes for Specific Constituents (10 of 10)
Aesthetic Parameters (cont)

40. Operational Goals for Water Treatment Plant
Outcomes for water treatment process :
water quality meets standard, quantity sufficient to meet demand,
operating costs, maintenance costs etc
Operational Goals for water treatment plant (day to day)
- filtration efficiency
unit filter run volume (UFRV)
volume processed before backwashing
- filter run length
time between backwashing
- terminal head loss
head lost across treatment plant
- filter maturation volume
volume of backwash water
- maximum contaminant level (MCL)
Operator knowledge and experience valuable
Consider similar treatment plants (benchmark)
with similar water issues

41. Factors in selecting Treatment Processes (1 of 7)

42. Factors in selecting Treatment Processes (2 of 7)

43. Factors in selecting Treatment Processes (3 of 7)

44. Factors in selecting Treatment Processes (4 of 7)

45. Factors in selecting Treatment Processes (5 of 7)

46. Factors in selecting Treatment Processes (6 of 7)

47. Factors in selecting Treatment Processes (7 of 7)

48. References
MWH, 2005, Water Treatment Principles and Design, 2nd ed., John Wiley and Sons, New York (TD430 .W ), pages