1. Treatment Engineering
Wastewater
Treatment Engineering
KNU Prof. Kwon

2. Wastewater Treatment Diagram

3. Wastewater Treatment Engineering
Introduction
Wastewater Characteristics
Wastewater Flow rates
Process analysis and selection
Physical Treatment
Chemical Treatment
Biological Treatment
Advanced Treatment
Unit Operation
Sludge disposal and reuse
Unit Process
Effluent reuse

4. Chapter 1 – Introduction (An Overview)
▶ What is Wastewater Treatment Engineering?
- Wastewater Treatment system
▶ Wastewater Treatment Flowchart
- Sludge disposal (Reclamation and Reuse)
- Level of Wastewater Treatment
▶ Status of Wastewater Treatment Plants

5. What is Wastewater Treatment Engineering?
Maintenance of
good water ecology
Improvement of
environmental condition
Good water space
pollution source control
water-purity control
water resources conserve
Recover reliability
Change of treatment
system concept

6. Wastewater Treatment System
Body part
domestic wastewater
industry wastewater
the others
vein
using water
artery
kidneys
Pretreatment
supply
Intercept sewage
Microcirculation
Sewerage
Wastewater Treatment
→ sewer
lung
Sewage disposal

7. Wastewater Treatment Flowchart I

8. Wastewater Treatment Flowchart II

9. Level of Wastewater Treatment
Treatment Level
Description
Preliminary
Removal of wastewater constituents such as rags, sticks, floatables, grit, and grease that may cause maintenance or operational problems with the treatment operations, processes, and ancillary systems
Primary
Removal of a portion of the suspended solids and organic matter from the wastewater
Advanced Primary
Enhanced removal of suspended solids and organic matter from the wastewater.
Typically accomplished by chemical addition or filtration
Secondary
Removal of biodegradable organic matter (in solution or suspension) and suspended solids.
Disinfection is also typically included in the definition of conventional secondary treatment
Secondary with nutrient removal
Removal of biodegradable organics, suspended solids, and nutrients
(nitrogen, phosphorus, or both nitrogen and phosphorus)
Tertiary
Removal of residual suspended solids (after secondary treatment), usually by granular medium filtration or micro screens. Disinfection is also typically a part of tertiary treatment.
Nutrient removal is often included in this definition
Advanced
Removal of dissolved and suspended materials remaining after normal biological treatment when required for various water reuse applications

10. Status of Wastewater Treatment Plants
자료출처 : 환경부

11. Inflow Quality vs Outflow Quality
자료출처 : 환경부

12. Planed water Quality vs Inflow Quality
Division
2010년
2009년
BOD SS
T-N
T-P
Planed Quality (mg/L)
150.0
149.6
32.3
4.2
149.4
148.5
30.7
3.9
Inflow Quality (mg/L)
141.2
139.5
33.8
3.8
143.5
140.9
34.4
Inflow/Planed (%)
94.1
93.2
107.4
90.5
96.1
94.9
112.1
102.7
Year
Item
Division
Planed water Quality vs Inflow Quality
Total
20% below
20~50% below
50~100% below
100% above
2010
BOD
Items
465 9 53
256
147
Component ratio
100
1.9
11.4
55.1
31.6
2009
432 7 56
247
122
1.6
13.0
57.2
28.2

13. Chapter 2 – Wastewater Flowrates
▶ Discharge type of domestic wastewater
- Combined sewer
- Separated sewer
▶ Components of Wastewater flows
- Infiltration and Inflow (I/I)
- Treatment of Storm water
- Estimations of Population

14. Discharge type of domestic wastewater
Combined sewer
Separated sewer

15. Infiltration and Inflow
Infiltration steady Inflow Direct Inflow Total Inflow Delayed Inflow

16. Treatment of Storm Water
domestic wastewater
Storm water
wastewater sewer
Storm intercept
intercept sewer
Wastewater Treatment
effluent
Separated sewer
Storm separator
combined sewer
Storm intercept
Rainy day
Combined sewer
Inflow

17. Variations of wastewater flowrates.
- It depend upon daily life cycle.
- “Daily variations”
- It is commonly observed seasonal variations
- “Seasonal variations”
“Variations of wastewater flowrates are rely on the
variations in water use.”
factors affecting municipal water use
(Climate, Community Size, Density of development, Economics… )
Short term variations
Long term variations

18. Estimating wastewater flowrates from water supply data
▶ Typical municipal water use
(Domestic : 36.4%, Industrial : 42.4%, Public : 6% Unaccounted system loss and leakage : 5.2%)
▶ Unaccountde system loss and lakage
- Less them 25 years old : form 10 to 20 percent of production for water
distribution system
- Older system : from 15 to 30 percent
- In small water systems : as much as 50 percent of production
- Attribution of meter error : as much as 50 percent

19. Estimations of Population
Method of least squares

20. Estimations of Population
Method of logistic curve
Time(t)
Geometric growth
Arithmetic growth
Declining, Logic growth
Populations(y)
T T2 Y1 Y2
Limit line

21. Estimations of Population
Geometric growth
Arithmetic growth

22. Estimations of Population
Declining growth

23. Chapter 3 – Wastewater Charateristics
▶ Source of pollution
- Point Source
- Non – Point Source
▶ Sampling
- Representative : The data must represent the sample
- Reproducible : same sampling and analytical protocols
Defensible : accuracy and precision
Usefulness : monitoring plan
▶ Method of sampling
Grab
Composite
Continuous

24. Constituents of concern in Wastewater Treatment
Reason for importance
Suspended solids
Suspended solids can lead to the development of sludge deposits and anaerobic conditions when untreated wastewater is discharged in the aquatic environment
Biodegradable
Organics
Composed principally of proteins, carbohydrates, and fats, biodegradable organics are measured most commonly in terms of BOD (biochemical oxygen demand) and COD (chemical oxygen demand). If discharged untreated to the environment, their biological stabilization can lead to the depletion of natural oxygen resources and to the development of septic conditions
Pathogens
Communicable diseases can be transmitted by the pathogenic organisms that may be present in wastewater
Nutrients
Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic environment, these nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amounts on land, they can also lead to the pollution of groundwater
Priority pollutants
Organic and inorganic compounds selected on the basis of their known or suspected carcinogenicity, mutagenicity, teratogenicity, or high acute toxicity. Many of these compounds are found in wastewater
Refractory organics
These organics tend to resist conventional methods of wastewater treatment. Typical examples include surfactants, phenols, and agricultural pesticides
Heavy metals
Heavy metals are usually added to wastewater from commercial and industrial activities and may have to be removed if the wastewater is to be reused
Dissolved inorganics
Inorganic constituents such as calcium, sodium, and sulfate are added to the original domestic water supply as a result of water use and may have to be removed if the wastewater is to be reused

25. Physical characteristics
Test (solid)
Description
Total solids (TS)
The residue remaining after a wastewater sample has been evaporated and dried at a specified temperature (103 to 105°C)
Total volatile solids (TVS)
Those solids that can be volatilized and burned off when the TS are ignited (500 ± 50°C)
Total fixed solids (TFS)
The residue that remains after TS are ignited (500 ± 50°C)
Total suspended solids (TSS)
Portion of the TS retained on a filter (see Fig. 2-4) with a specified pore size, measured after being dried at a specified temperature (105°C). The filter used most commonly for the determination of TSS is the Whatman glass fiber filter, which has a nominal pore size of about f.Lm
Volatile suspended solids (VSS)
Those solids that can be volatilized and burned off when the TSS are ignited (500 ± 50°C)
Test
Fixed suspended solids (FSS)
The residue that remains after TSS are ignited . (500 ± 50°C)
Total dissolved solids (TDS) (TS - TSS)
Those solids that pass through the filter, and are then evaporated and dried at specified temperature. It should be noted that what is measured as TDS is comprised of colloidal and dissolved solids. Colloids are lypically in the size range from to 1 f.Lm
Total volatile dissolved solids (VDS)
Those solids that can be volatilized and burned off when the TDS are ignited (500 ± 50°C)
Fixed dissolved solids (FDS)
The residue that remains after TDS are ignited (500 ± 50°C)

26. Interrelationships of solids found in water and wastewater
TS = Total Solids
TSS = Total Suspended Solids
TDS = Total Dissolved Solids
VSS = Volatile Suspended Solids
FSS = Fixed Suspended Solids
VDS = Volatile Dissolved Solids
FDS = Fixed Dissolved Solids
TVS = Total Volatile Solids
TFS = Total Fixed Solids

27. Turbidity and color
▶ Turbidity Unit : NTU(Nephelometry Turbidity Unit) - TSS, mg/L = (TSSf)(T) Where, TSSf : factor used to convert Turbidity → suspended solids, (mg/L)/NTU - Absorption/Transmittance ▶ A = log(Io/I) Where, A : absorbance, a.u/cm Io : initial detector reading for blank I : final detector reading for sample Transmittance T, % = (I/Io) × 100 Where, T = 10-(a.u)/cm → T, % = 10-(a.u)/cm × 100

28. Temperature
▶ Van’t Hoff – Arrhenius relationship : Where, K = reaction rate constant T = temperature, K or Co E = constant characteristic of the reaction, J/mole R = ideal gas constant, J/mol.K

29. Integration of given Eg., between the limit T1 and T2

30. Nitrogen ▶ Sources of Nitrogen ▶ Forms of Nitrogen
The nitrogenous compounds of plant and animal origin
NaNO3
Atmospheric Nitrogen
▶ Forms of Nitrogen
Organic Nitrogen ↓
Ammonia Nitrogen (NH4+)
Nitrite Nitrogen (NO2-)
Nitrate Nitrogen (NO3-)
Atmospheric Nitrogen ( N2 )
Total kjeldahl nitrogen(TKN)
Nitrification
Denitrification

31. Distribution of ammonia (NH3) and Ammonium ion (NH4+) as a function of pH

32. Generalized nitrogen cycle in the aquatic and soil environment

33. Alkalinity
▶ Results from presence of hydroxides (OH-), Carbonates(CO3-2) and bicarbonates (HCO3-)
▶ Relation pH and alkalinity

34. Basis for BOD test ▶ Oxidation ▶ Synthesis ▶ Endogenous Respiration
CHONS + O2 + bacteria → CO2 + H2O + NH3 + Other products + energy
▶ Synthesis
CHONS + O2 + bacteria + Energy → C5H7O2N(New cell tissue)
▶ Endogenous Respiration
CHONS + 5O2 → 5CO2 + NH3 + 2 H2O
These oxygen demands are Known as ultimate carbonaceous
or first – stage BOD (UBOD)

35. Procedure for setting up BOD test bottles : with unseeded dilution

36. Procedure for setting up BOD test bottles : with seeded dilution water

37. Definition sketch for the exertion of the carbonaceous and nitrogenous biochemical oxygen demand in a waste sample

38. Nitrification in BOD test
▶ Conversion of ammonia to nitrite (by Nitrosomonas) NH O2 → HNO2 + H20 ▶ Conversion of nitrite to nitrate (by Nitrobactor) HNO O2 → HNO3 + H20 ▶ Overall conversion of ammonia to nitrate NH3 + 2 O2 → HNO3 + H20 ⇒ This reaction is called the nitrogenous biochemical Oxygen demand (NBOD or NOD). ⇒ We have to know “competition of microbe”

39. Functional analysis of the BOD test : idealized representation of the BOD test

40. Modeling of BOD reaction
▶ The amount of organic material remaining at any time “t” is governed by “first – order” function
dLt/ dt = -kLt (1)
Where, Lt : BOD remaining at time t
K : reaction rate, day-1
Lo : BOD remaining at time, t = 0 (Ultimate BOD)

41. Modeling of BOD reaction
▶ Intergrating between limits of UBOD and Lt and t = 0
and t = t
Lt = Lo • e -kt (2)
▶ The BOD exerted up to time t is given by
Y(t) = Lo - Lo • e -kt = Lo (1 - e -kt)
▶ For example, the BOD exerted up to time 5 days is
BOD5 = Lo (1 - e -kt)

42. Effect of the rate constant K1 on BOD (for a unit UBOD value)

43. Other Organic Organic Matter
▶ COD(Chemical Oxygen Demand)
CnHaObNc + dCr2O7-2 + (8d+c) H+ →
nCO H2O + CNH4+ + 2dCr +3
where, d =
⇒ COD data for sample is always higher than BOD data.
Some of reasons are as follows :
COD = BDCOD + NBDCOD
where BDCOD = UBOD (BOD20)
if NBDCOD = O ⇒ COD = BOD20

44. Example BOD-COD-TOC A wastewater contains the following :
- ethylene glycol (C2H6O2) : 150 mg/L
- phenol (C6H6O) : 100 mg/L
- sulfide (S-2) : 40 mg/L
- ethylene diamine hydrate (C2H10N2O) : 125 mg/L
(NBD)
If, BOD20 = 0.92COD
1) Compute the COD and TOC
2) Compute the BOD5 (k10 : 0.2 day-1)
3) After biological treatment, BOD5 is 25 mg/L.
Estimate the COD (k10 : 0.1 day-1)

45. Example BOD-COD-TOC
- ethylene glycol (C2H6O2) C2H6O O2 → 2CO2 + 3H2O - phenol (C6H6O) C6H6O + 7O2 → 6CO2 + 3H2O - sulfide (S-2) S-2 + 2O2 → SO4-2 - ethylene diamine hydrate (C2H10N2O) C2H10N2O + 2.5O2 → 2CO2 + 2H2O + 2NH3

46. Loading rate ▶ Statistical Analysis of wastewater flowrate.
▶ Statistical parameters used for the analysis of wastewater data.
Parameter
Definition
Mean value(S)
= mean value
fi = frequency(for ungrouped data fi = 1)
Xi = midpoint of the ith data rang (for ungrouped
data Xi = the ith observation)
n = number of observations (Note Σ fi = n)
Median value
The middlemost observation data.
(if two middlemost observed , the arithmetic mean to the two)

47. Loading rate parameter Definition Standard deviation
n = number of observations (Note Σ fi = n)
S = standard deviation
Xi = midpoint of the ith data rang (for ungrouped
data Xi = the ith observation)
= mean value
Coefficient of variation
Cv = coefficient of variation, percent
S = standard deviation
Mode
The value occurring with the greatest frequency in a set of observations is known as the mode. If a continuous graph of the frequency distribution is drawn, the mode is the value of the high point, or hump, of the curve. In a symmetrical set of observations, the mean, median, and mode will be the same value

48. Loading rate Using the following daily data obtained from dischanger.
▶ Example
Using the following daily data obtained from dischanger.
determine the statistical characteristics and predict the mixmum daily flowrate.
Day no.
Flowrate, m3/day 1
2,900 8
3,675 2
3,040 9
3,810 3
3,540 10
3,450 4
3,360 11
3,265 5
3,770 12
3,180 6
4,080 13
3,135 7
4,015

49. Loading rate
▶ Solution plot the flowrate data using the log-probability method.
Rank Serial no, m
Flowrate, m3/day
Plotting position, % 1
2,900
7.1 2
3,040
14.3 3
3,135
21.4 4
3,180
28.6 5
3,265
35.7 6
3,360
42.9 7
3450
50.0 8
3,540
57.1 9
3,675
64.3 10
3,770
71.4 11
3,810
78.6 12
4,015
85.7 13
4,080
92.9
m3/day

50. Typical wastewater constituent for various countries
Contry/
constituent
BOD,
g/capita.d
TSS,
TKN,
NH3-N
Total P,
Korea
48.6~50.7
10.6~13.0
1.24~1.45
Germany
55~68
82~96
11~16 ND
1.2~1.6
India
27~41
Italy
49~60
55~82
8~14
0.6~1
Japan
40~45
1~3
0.15~0.4
Palestineb
32~68
52~72
4~7
3~5
0.4~0.7
Sweden
68~82
0.8~1.2
United StatesC
50~120
60~150
9~22
5~12
2.7~4.5

51. Typical probability plots for flowrate, BOD, and TSS

52. Illustration of diurnal wastewater flow, BOD, and mass loading variability

53. Typical ratios of averaged sustained peak and low daily fiowrates to average annual daily flowrates for time periods up to 30 days

54. Peaking factor curve (ratio of peak hourly to average daily flow)