8/17/2019 Lecture EE 2-3

1/25

Examples

Example 1. Determine the 1-

day BOD and ultimate first

stage BOD for a wastewater

whose 5-day, 20C BOD is

200 mg/L. k = 0.23 day-1 

Example 2. 5-day BOD at

20C for a domestic sewage

is 250 mg/L. Determine 5-

day BOD at 30C if k20

= 0.1

day-1. Calculate also the

total number of days for the

value of BOD at 30C to

reduce to 250 mg/L. Plot

your results graphically and

explain the significance of

your findings.

8/17/2019 Lecture EE 2-3

2/25

Examples

Example 3. A laboratory

test was carried out to

determine the ultimate

BOD Lo and k for thepurpose of design. The

results are as below. Using

the appropriate linearised

plot, determine Lo and k.Comment briefly on your

answer.

T (day) yt (mg/L)

1 18.13

2 32.97

3 45.12

4 55.07

5 63.21

6 69.88

8/17/2019 Lecture EE 2-3

3/25

Examples

Example 4. Given the

following lab data,

determine the SOUR

values.

Time (min) DO (mg/L)

1 7.00

2 6.95

3 6.90

4 6.85

5 6.80

6 6.75

7 6.70

8 6.65

9 6.60

10 6.55

11 6.50

12 6.45

13 6.40

14 6.35

15 6.30

8/17/2019 Lecture EE 2-3

4/25

  Inorganic Matter

• Source:

(1) Geologic formation with which the water comes in contact with.

(2) Treated or untreated wastewater that was discharged into it.

(3) Natural evaporation removes some of the surface water and leaves the inorganic

substances behind.

• What are they?

(1) pH

(2) Chlorides

(3) Alkalinity

(4) Nitrogen

(5) Phosphorus

(6) Heavy metals

Chemical

Constituents

8/17/2019 Lecture EE 2-3

5/25

pH

• Definition:

(1) Indicate Hydrogen-ion concentration [H+], acidic or alkaline water.

(2) Closely connected with the extent to which water molecule dissociate.

H2O H+ + OH- 

pH = -log10[H+]

• Source:

(1) Industrial wastewater.

• Impact:

(1) Wastewater with extreme pH is difficult to treat by biological means, as microbialsurvivals are highly dependent to the pH.

(2) May alter the pH of receiving water bodies.

(3) May affect treatment process efficiency and chemical dosage.

•Measurement:

(1) pH meter (2) pH paper (3) Indicator solutions that change color with different pH.

• Application:

pH 6.0-9.0 (Standard A, EQA 1974) and pH 5.5-9.0 (Standard B) for sewage, industrial andleachate discharge.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

6/25

pH meter

8/17/2019 Lecture EE 2-3

7/25

  Chloride

• Definition:

(1) Chloride is a negatively charged ion that is formed when chlorine gains an additionalelectron.

(2) Chloride is generally found in the form of salts, most commonly sodium and potassiumsalts, which are very soluble in water.

• Source:

(1) Leaching of chloride-containing rocks and soils.

(2) Saltwater intrusion.

(3) Agricultural, industrial, and domestic wastewater discharge.

(4) Groundwater infiltration.

• Impact:

Interfere the treatment processes.• Measurement:

Potentiometric method.

• Application:

Not regulated under EQA 1974.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

8/25

Potentiometric method for chloride

measurement

8/17/2019 Lecture EE 2-3

9/25

Alkalinity

• Definition:

(1) Alkalinity is a measure of the capacity of water to neutralize acids.

(2) Alkalinity of water is due primarily to the presence of bicarbonate, carbonate, and hydroxide ions.Salts of weak acids, such as borates, silicates and phosphates, may also contribute. Salts of certainorganic acids may contribute to alkalinity in polluted or anaerobic water, but their contributionusually is negligible.

(3) Bicarbonate is the major form of alkalinity. Carbonates and hydroxide may be significant when algalactivity is high and in certain industrial water and wastewater, such as boiler water.

• Source:

(1) The main sources for natural alkalinity are rocks which contain carbonate, bicarbonate, andhydroxide compounds. Borates, silicates, and phosphates also may contribute to alkalinity.

(2) Limestone is rich in carbonates, so waters flowing through limestone regions or bedrock containingcarbonates generally have high alkalinity - hence good buffering capacity.

(3) Areas rich in granites and some conglomerates and sandstones may have low alkalinity and,therefore, poor buffering capacity.

• Impact:

Affect wastewater treatment process i.e. affect chlorine residual in water treatment effluent.

• Measurement:

Titration against a standard acid. Unit: mg/L as CaCO3.

• Application:

Not regulated under EQA 1974.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

10/25

Alkalinity

measurement

using titration

method

8/17/2019 Lecture EE 2-3

11/25

  Nitrogen

• Definition:

Served as nutrients and important for biological growth (C:N:P ratio 100:5:1). Can be in a form of:

(1) Organic Nitrogen – determine by Kjeldahl method.

(2) Ammonia (NH3 ) (3) Nitrate (NO3) (4) Nitrite ((NO2)

• Source:

(1) Runoff from fertilized lawns and croplands.(2) Runoff from animal manure.

(3) Failing septic tank.

(4) Wastewater treatment plant.

• Impact:

(1) Exert oxygen demand in stream and wastewater.

(2) Algal bloom.

(3) ‘Blue baby’ syndrome. 

• Measurement: Total Kjedahl Nitrogen Method.

• Application:

(1) Ammoniacal nitrogen: 10 mg/L (Standard A,) and 20 mg/L (Standard B) for sewage and

industrial discharge. 5 mg/L for leachate discharge.(2) Nitrate: 20 mg/L (Standard A,) and 50 mg/L (Standard B) for sewage discharge.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

12/25

Total Kjedahl

Nitrogen• The kjeldahl nitrogen in the sample is

first converted to ammonia by metal-catalyzed acid digestion.

• The resulting ammonia is thenseparated from the sample bydistillation.

•

The ammonia released is captured ina dilute sulfuric acid solution.

8/17/2019 Lecture EE 2-3

13/25

  Phosphorus

• Definition:

Served as nutrients and important for biological growth (C:N:P ratio 100:5:1). Can be

in a form of:

(1) Orthophosphate (2) Polyphosphate (3) Organic Phosphate

• Source:

(1) Runoff from fertilized lawns and croplands.

• Impact:

(1) Algal bloom.

• Measurement:

Colorimetry technique.

• Application:

5 mg/L (Standard A,) and 10 mg/L (Standard B) for sewage discharge.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

14/25

Phosphorus

measurement

8/17/2019 Lecture EE 2-3

15/25

  Heavy metals

• Definition:

(1) Nickel (Ni), manganese (Mn), Lead (Pb), Chromium (Cr), Cadmium (Cd), Zinc (Zn),Copper (Cu), Iron (Fe), and Mercury (Hg).

(2) Many of them are also classified as priority pollutants.

• Source:

(1) Industrial wastewater.

• Impact:(1) Absence of sufficient quantity could limit growth of biological life.

(2) Presence in excessive quantities will become toxic and interfere biological treatmentprocesses.

• Measurement:

Atomic absorption spectrophotometer (AAS) with graphite, inductive coupled plasma (ICP)for detection.

• Application:

(1) Not regulated for sewage discharge.

(2) Hg, Cd, Cr, As, Cn, Pb, Cu, Mn, Ni, Sn, Zn, B, Fe, Ag, Al, Se, Ba, Fl is regulated under EQA1974 for industrial and leachate discharge.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

16/25

Atomic Absorption

Spectrophotometer

& Periodic Table of

the Elements

8/17/2019 Lecture EE 2-3

17/25

 Gases

• What are they?

(1) Nitrogen N2

- Common gases in the atmosphere and will

be found in all waters exposed to the

atmosphere.

(2) Oxygen O2

- O2is only partly soluble in water. In the

water, expressed as dissolved oxygen

(DO).

- The solubility is highly affected by

temperature.

- Desirable because it presents theformation of noxious order and crucial for

aquatic life.

(3) Carbon Dioxide CO2

- Common gases in the atmosphere and will

be found in all waters exposed to the

atmosphere.

(4) Hydrogen Sulfide H2S

- Derived from the decomposition of the

organic matter present in wastewater.

- The blackening of wastewater and sludge

usually results from the formation of H2S

that has combined with the Iron present

to form Ferrous Sulfide (FeS).

(5) Ammonia NH3

- Derived from the decomposition of the

organic matter present in wastewater.

(6) Methane CH4

- The principal by-products of the anaerobicdecomposition of the organic matter

present in wastewater.

- Combustible hydrocarbon at high fuel

value.

- Highly combustible and explosive.

• Gases are not regulated under EQA 1974.

Chemical

Constituents

8/17/2019 Lecture EE 2-3

18/25

Gas

Chromatography

for gasmeasurement

8/17/2019 Lecture EE 2-3

19/25

Pathogenic Organisms

• Definition:

4 principal categories of pathogenic organisms:

(i) Bacteria – salmonella typhi (caused typhoidfever), vibrio cholerae (caused cholera),salmonella (caused salmonellosis), E.coli(caused gastroenteritis).

(ii) Viruses – hepatitis A, meningitis, JapaneseEncephalitis (JE), ebola, influenza (causedbird flu), H1N1 influenza.

(iii) Protozoa – cryptosporodium (causedcryptosporidiosis), giardia lamblia (causedgiardiasis).

(iv) Helminths – trichuris trichiura (causedtrichuriasis)

•

Source:Discharged by human beings who are infectedwith disease or who are carriers of a particulardisease.

• Application:

Not regulated under EQA 1974.

Indicator organisms

• The most basic test for bacterial contaminationof a water supply is the test for total coliformbacteria.

• Total coliform counts give a general indication ofthe sanitary condition of a water supply.

• Total coliforms

- Include bacteria that are found in the soil, in

water that has been influenced by surfacewater, and in human or animal waste.

- Includes Escherichia coli , Klebisella, Citrobactor,Enterobacter.

- Identified by incubation at 35C with LTB culturemedium.

• Fecal coliforms

- Sub group of total coliforms.

- Considered to be present specifically in the gutand feces of warm-blooded animals.

- Identified by incubation at 44.5C with EC culturemedium.

• Escherichia coli (E. coli) 

- Member of fecal coliforms group.

- E. coli is considered to be the species of coliformbacteria that is the best indicator of fecal

pollution and the possible presence ofpathogens.

Biological

Constituents

8/17/2019 Lecture EE 2-3

20/25

• 2nd step: Transfer 1 mL sample from each of theserial dilutions to each of 3 or 5 fermentationtubes containing culture medium and aninverted gas collection tube.

• 3rd step: Total coliform determination: Incubateat 35⁰C for 24 hour (Culture medium: LTB). 

• 4th step: Fecal Coliform determination: Incubateat 44.5 ⁰ C for 48 hour (Culture medium: ECbroth) or E.Coli determination: Incubate at 44.5 ⁰C for 48 hour (Culture medium: EC broth).

• 5th step: Read the results. Positive tubes areturbid and has bubbles in the inverted tubes.

• 6th step: Use MPN table to get the MPN values.Unit: MPN/100 ml (MPN = most probable

number) .

3

+

+

+

+

-

+

2

• Measurement: Multiple tubefermentation technique

• Principle: dilution to extinction.

• 1st step: Prepare a series of serial

dilution.

8/17/2019 Lecture EE 2-3

21/25

Example 5

No 100

No

dil.

10-1

1x

dil.

10-2

2x

dil.

10-3

3x

dil. 

10-4

4x

dil.

10-5

5x

dil.

10-6

6x

dil. 

Step 1:

Significant

dilution

Step 2:

MPN from table

Largest significant dilution

A 5/5 5/5 5/5 5/5 5/5 3/5 0/5 5-3-0 7.92

10− = 79,200

 

B 5/5 5/5 5/5 4/5 5/5 1/5 0/5 4-5-1 4.8310−

 = 4,830

 

C 5/5 5/5 5/5 0/5 1/5 0/5 0/5 0-1-0 0.18

10− = 180

 

D 5/5 5/5 5/5 5/5 3/5 1/5 1/5 3-1-1 1.37

10−

 = 13,700

 

E 5/5 5/5 5/5 4/5 4/5 1/5 0/5 4-4-1 3.98

10− = 3,980

 

F 5/5 5/5 5/5 5/5 5/5 5/5 2/5 5-5-2 54.22

10−  = 542,200

 

8/17/2019 Lecture EE 2-3

22/25

8/17/2019 Lecture EE 2-3

23/25

 Measurement: Membrane filter technique

8/17/2019 Lecture EE 2-3

24/25

Measurement: Bacterial counter

technique.

8/17/2019 Lecture EE 2-3

25/25

Water Characterization Studies.

Clockwise: (1) Water sampler (2) Water flow velocitymeasurement (3) Potable sampler for DO, temperature etc. (4)Benthic organisms sampler.