4. Course Outline
• Introduction to Water and Wastewater
– EXPLAIN and DIFFERENTIATE what is water and
waste water
– LIST and DIFFERENTIATE the water and
wastewater quality and their characteristics
– IDENTIFY wastewater constituent and
DIFFERENTIATE into their group
– EXPLAIN AND CALCULATE water quality and
wastewater standard applied in Malaysia
5. Water and wastewater
• What is water?
• What is wastewater?
• What are the differences between water
and wastewater?
6. Water
• 70% of earth consist water
• 3% is freshwater and 97% is saline water
• Water is a tasteless, odorless and
colourless liquid
• Water is the chemical substance with
chemical formula H2O: one molecule of
water has two hydrogen atoms
covalently bonded to a single oxygen
atom.
7. Wastewater
• Wastewater is not just sewage. It also include a
liquid waste discharged by domestic residences,
commercial properties, industry, and/or agriculture
and can encompass a wide range of potential
contaminants and concentrations.
• Very common, it refers to the municipal
wastewater that contains a broad spectrum of
contaminants resulting from the mixing of
wastewaters from different sources.
8. In class activity 1:
Question: How does the drinking water
get to your home?
Answer with your partner next to you?
9. 1. Collection (skies/precipation)
2. Clean/treatment (physical and chemical
process – remove germ/harmful)
3. Storage and delivery
Adequate pressure flow
Transport to home by pipe networks
10. Comparison between water and
wastewater
Water Wastewater
Clean Polluted
Water supply Effluent
Source : Surface and
groundwater
Source : toilet,
kitchen, sinks, etc
Consist 99.9% water
and mineral
Consist solid and
organic waste
11. Why treatment of wastewater
needed?
Why
Fisheries
Wildlife
Habitats
Recreation and
Quality of Life
Health
Concerns
12. But…
• Major aim of wastewater treatment is
to remove as much of the
suspended solids as possible
before the remaining water, called
effluent, is discharged back to the
environment.
13. Terms in wastewater
• Influent: wastewater flowing into a treatment plant
• Effluent: treated wastewater, flowing from a lagoon, tank,
treatment process, or treatment plant
• Activated sludge: sludge particles produced by the
growth of microorganisms in aerated tanks as a part of
the activated sludge process to treat wastewater
• Aeration: exposing to circulating air; adds oxygen to the
wastewater and allows other gases trapped in the
wastewater to escape (the first step in secondary
treatment via activated sludge process)
14. • Biochemical Oxygen Demand (BOD): a laboratory
measurement of wastewater that is one of the main
indicators of the quantity of pollutants present; a
parameter used to measure the amount of oxygen that
will be consumed by microorganisms during the biological
reaction of oxygen with organic material
• Biosolids: sludge that is intended for beneficial use, that
must meet certain government specified criteria
depending on its use (e.g., fertilizer or soil amendment).
• decomposition: process of breaking down into constituent
parts or elements
15. • Domestic wastewater: wastewater that comes
primarily from individuals, and does not
generally include industrial or agricultural
wastewater
• Grit chamber: a chamber/tank used in primary
treatment where wastewater slows down and
heavy, large solids (grit) settle out and are
removed
• municipal: relating to a municipality (city, town,
etc.). Municipal wastewater is primarily domestic
wastewater.
16. • lagoons (oxidation ponds or stabilization ponds):
a wastewater treatment method that uses ponds to
treat wastewater. Algae grow within the lagoons
and utilize sunlight to produce oxygen, which is in
turn used by microorganisms in the lagoon to
break down organic material in the wastewater.
Wastewater solids settle in the lagoon, resulting in
effluent that is relatively well treated, although it
does contain algae.
17. • primary treatment: the first stage of wastewater
treatment that removes settle able or floating solids only;
generally removes 40% of the suspended solids and 30-
40% of the BOD in the wastewater
• secondary treatment: a type of wastewater treatment
used to convert dissolved and suspended pollutants into
a form that can be removed, producing a relatively highly
treated effluent.
• sedimentation: the process used in both primary and
secondary wastewater treatment, that takes place when
gravity pulls particles to the bottom of a tank (also called
settling).
18. • settling tank (sedimentation tank or clarifier): a
vessel in which solids settle out of water by during
wastewater or drinking water treatment processes.
• sludge: any solid, semisolid, or liquid waste that
settles to the bottom of sedimentation tanks (in
wastewater treatment plants or drinking water
treatment plants) or septic tanks
• tertiary treatment: any level of treatment beyond
secondary treatment, which could include filtration,
nutrient removal (removal of nitrogen and
phosphorus) and removal of toxic chemicals or
metals; also called “advanced treatment” when
nutrient removal is included
19. • total suspended solids (TSS): a laboratory
measurement of the quantity of suspended solids
present in wastewater that is one of the main
indicators of the quantity of pollutants present
• trickling filter process: a biological treatment
process that uses coarse media (usually rock/
plastic) contained in a tank that serves as a
surface on which microbiological growth occurs.
• turbidity: Cloudy/muddy appearance of a naturally
clear liquid caused by the suspension of
particulate matter
20. Wastewater Characteristics
• PHYSICAL CHARACTERISTICS
– Physical characteristics of wastewater include
those items that can be detected using the
physical senses. They are:
• temperature
• color
• odor
• solids
21. • Temperature
-Temperature of wastewater varies greatly
depending upon the type of operations being
conducted at your installation.
-Changes in wastewater temperatures affect the
settling rates, DO levels, and biological action.
-Temperature of wastewater becomes extremely
important in certain wastewater unit operations
such as sedimentation tanks and recirculating
filters.
22. • Color
– Color of wastewater containing dissolved oxygen
(DO) is normally gray. Black-colored wastewater
usually accompanied by foul odors, containing little or
no DO, is said to be septic.
23. • Odor
– Domestic sewage should have a musty odor. Bubbling gas
and/or foul odor may indicate industrial wastes, anaerobic
(septic) conditions, and operational problems.
24. • Solids
– Wastewater is normally 99.9% water and 0.1% solids.
If a wastewater sample is evaporated, the solids
remaining are called total solids.
– Amount of solids in the drinking water system has a
significant effect on the total solids concentration in
the raw sewage. Industrial and domestic discharges
also add solids to the plant influent. There are many
different ways to classify solids. The most common
types are dissolved, suspended, settleable, floatable,
colloidal, organic, and inorganic solids.
– Part of the total solids is dissolved in wastewater.
Much like sugar dissolves in coffee, many solids
dissolve in water.
25. • Biological treatment units such as trickling filters and activated
sludge plants convert some of these dissolved solids into settleable
solids that are then removed by sedimentation tanks.
• Those solids that are not dissolved in wastewater are called
suspended solids.
• When suspended solids float, they are called floatable solids or
scum.
• Suspended solids that settle are called settleable solids, grit, or
sludge.
26. Wastewater Characteristics
• CHEMICAL CHARACTERISTICS
–Chemical characteristics of wastewater
of special concern are :
• pH
• DO (dissolved oxygen)
• oxygen demand
• nutrient
• toxic substances
27. • pH
-To describe the acid or base
properties of water solutions.
-pH value < 7 in the wastewater
plant influent may indicate septic
conditions of wastewater. pH
values <5 and > 10 usually
indicate that industrial wastes
exist and are not compatible with
biological wastewater operations.
-Pretreatment of these wastes at
the source is usually required
since extreme pH values may
damage biological treatment units.
28. •Dissolved oxygen
– DO in wastewater has a great effect on the
characteristics of the water
– Wastewater that has DO is called aerobic or fresh.
Aerobic raw sewage is usually gray in color and has a
musty odor.
– Wastewater that has no DO is called anaerobic or
septic. Anaerobic raw sewage is usually black and
has an offensive hydrogen sulfide or rotten egg odor.
29. • Oxygen Demand
– The amount of oxygen used by bacteria and
other wastewater organisms as they feed upon
the organic solids in the wastewater.
– Chemical tests such as the BOD (biochemical
oxygen demand), the COD (chemical oxygen
demand), the ODI (instantaneous oxygen demand
or oxygen demand index), and the TOC (total
organic carbon) measure the "strength" of
sewage. It is important that organic wastes be
removed to protect the receiving body of water into
which the wastewater plant is discharging.
30. • Nutrients
– Nutrients are life-supporting nitrogen and phosphorus.
They stimulate excessive growths of algae and other
aquatic plant life. They are always present in
domestic wastewaters and are not removed
during conventional primary and secondary
treatment.
– Removal is accomplished by processes in addition to
normal wastewater treatment or tertiary treatment,
when specific reuse requirements require it.
31. • Toxic Chemicals
– Most industrial installations use various types
of toxic chemicals, the discharges of which
can be harmful to wastewater treatment
processes. These toxic chemicals should
be pretreated or removed before the
wastewater enters the collecting system.
33. • Bacteria
– Sewage consists of vast quantities of bacteria,
most of which are harmless to man.
– Bacteria can also be classified according to
their dissolved oxygen requirement.
• Aerobic bacteria are bacteria that require
dissolved oxygen to live.
• Anaerobic bacteria cannot live if dissolved
oxygen is present.
• Facultative bacteria can live with or without
dissolved oxygen.
34. • Viruses
– Wastewater often contains viruses that may produce
diseases.
– Outbreaks of infectious hepatitis have been traced through water
systems because of wastewater entering the supply.
sedimentation, filtration, and disinfection, if used efficiently,
usually provide acceptable virus removal.
• Parasites
– There are also many species of parasites carried by wastewater.
The life cycle of each is peculiar to the given parasite. Some are
dangerous to man and livestock, particularly during certain
stages of the life cycle.
– Amoebic dysentery is a common disease caused by amoebic
parasites. Chlorination, chemical precipitation, sedimentation, or
sand filtration is used to ensure protection against parasites
35. In class activity 2
Question: Explain your role as good citizen
in relation to sanitation.
Discuss/Answer with your next partner.
36. Wastewater Treatment Methods
in Malaysia
• Methods may be classified into
i) Physical unit operations,
ii) Chemical unit processes and
iii) Biological unit processes.
37. Wastewater Treatment Methods in Malaysia
(Flowsheet)
50% removal
of contaminant
Aim: To reduce the volume of solid
38. Wastewater Treatment Methods
in Malaysia
• Physical Unit Operations
– which use the application of
physical forces to treat sewage.
–These include screening, mixing,
flocculation, sedimentation, filtration
and flotation
39. Wastewater Treatment Methods
in Malaysia
• Biological Unit Processes
– Methods which remove pollutants by
biological activity. Biodegradable organic
substances are converted into gases that
escape to the atmosphere and cell tissue is
removed by settling. Oxidation Pond Basic
Biological Reaction in an Oxidation Pond.
40. Wastewater Treatment Methods
in Malaysia
• Chemical Unit Processes
– Treatment methods in which the removal or
conversion of pollutants by the addition of
chemicals or by chemical reactions are
known as Chemical Unit Processes. These
include precipitation, adsorption and
disinfection.
42. Basic Biological Reaction in an Oxidation Pond
For the oxidation
pond, write the
biological reaction
process based on the
given figure.
You can read other
related information
via
articles/books/internet
sources
43. Effluent Standards
• Domestic sewage treatment is mainly designed to
produce an effluent low in solids and organic.
• Standards have been established for the quality of
effluent discharged from treatment plants to
receiving waters. These take the form of acceptable
upper limits for various effluent contaminants.
• Effluents from treatment plants are regularly
sampled and tested in laboratories to ensure that
these standards are being met and that treatment plants
are being operated correctly.
44. Effluent Standards
• Pollutants in sewage are measured in order to better
understand and thus facilitate the treatment of
sewage as well as to examine the effects of effluent
or treated sewage on the environment.
• Effluent from all public sewage treatment plants is
sampled at regular intervals and tested in
laboratories to ensure that it meets the required
standards.
• Tests are carried out as part of a monitoring
program in keeping with Indah Water's operational
license conditions and to ensure the efficient
operation of treatment processes.
45. • Volume of effluent discharge per day can
be used to calculate the Dry Weather Flow
(DWF).
• DWF: Average daily sewage flow entering
a sewage treatment or sewer measured
following 7 days without rain and during
which on the preceding 7 days, rainfall did
not exceed 25 mm on any day.
Effluent Standards
46. Effluent Standards
• Two most important parameters measured are
Biochemical Oxygen Demand (BOD) and Suspended
Solids (SS).
• BOD is an amount of oxygen required to
microorganism to break down organic matter in
wastewater. High BOD means that sewage will rapidly
consume all the naturally-DO in streams, rivers and
lakes, thus killing off all aquatic life, and rendering the
water septic and foul-smelling.
• SS is a measure of the undissolved material in
sewage. High SS leads to sludge deposits in the
waterways, thus causing significant environmental
deterioration.
47. Effluent Standards
Standard BOD (mg/L) SS (mg/L)
A 20 50
B 50 100
• Effluent that is discharged upstream (or any sensitive
area) of a water supply intake should meet Standard A,
while effluent that is discharged downstream has to meet
Standard B. These standards are set by the
Environmental Quality Act 1974.
51. BOD Value
Type of
wastewater
BOD load per day
(gram/unit.day)
TKN Load
per day
(gram/unit.
day)
Sewage 55 -
Cow 498 222
Buffalo 347 107
Sheep 102 22
Pig 137 23
BOD load and TKN composition per day for varies wastewater (Nicoll, 1988)
52. BOD Calculation
• BOD value is very important to estimate wastewater
concentration with knowing the population (example:
people/unit)
• For example : BOD load for 100 people is (100 x 55
gram/day), equal to 55,000 gram/day.
• If we know the flowrate, we can calculate the BOD value
BOD Load per day = gram/unit. day
For human normally refer to capita!
53. Question 1
Calculate BOD value produced
by 1000 people with total
flowrate is 225m3/day. Assume
BOD load is 55
gram/capita.day
54. Question 2
If BOD5 concentration for
wastewater is 200mg/liter with
water consume is 200
liter/capita.day. Calculate BOD5
load for this wastewater
55. Question 3
Calculate DWF value for 10000 people
if water consumption rate is 200
liter/capita.day?
56. Question 4
Table 1 shows the information of daily
wastewater flowrate and BOD5 concentration
for an urban area. Determine the average
daily wastewater flowrate and BOD5
concentration.
58. One wastewater treatment plant discharge
effluent with 2.0 m3/s and BOD 20 mg/liter
into a river with 10 m3/s and BOD 2.0
mg/liter. Calculate BOD value at lower
stream.
Question 5
59. A wastewater flow of 10,000 m3/day is received
at a sewerage treatment plant in Seberang Prai.
The population served is 40,000 and there are a
few industries in addition. If the BOD5 of the
wastewater is 400 mg/L estimate the BOD due
to:
i. Domestic sewage
ii. Industries
use BOD5 perday = 54 gram
Question 6
60. • For environmental engineer they are more interested on BOD exerted.
• Test – DO measurement
• Use 5-day result to total or ultimate BOD (yu) or BOD at some
other time.
• In the lab/experiment: BOD = DOI – DOF/P
where, DOI , DOF = Initial and final DO (mg/l), P = decimal fraction of sample in
the 300 –ml bottle
Organic oxidized
Cont. BOD Calculation
61. • With assumption: BOD reaction follow first order kinetic
• k = 0.1 to 0.5 per day depending on the nature of the organic
molecules
• k is temperature-dependent, because microorganisms are more
active at high temperature, where k values are higher (Figure).
• ᶱ = temperature correction factor (usually =1.047)
Reaction Constant
62. The BOD of a wastewater is suspected to range from 50
to 200 mg/L. Three dilution are prepared to cover this
range. The procedure is the same in each case. First the
sample is placed in the standard BOD bottle and is then
diluted to 300 ml with organic-free, O2-saturated water.
The initial DO is determined and the bottles tightly
stoppered and places in the incubator at 20oC for 5
days, after which the DO is again determined. If the third
value is disregarded (the final DO being less than 2
mg/L), calculate the average BOD.
Explain Why in the lab BOD test is chosen at 5 days?
Question 7
63. Lab Data
Wastewater,
ml
DOI, mg/L DOF, mg/L
5 9.2 6.9
10 9.1 4.4
20 8.9 1.5
Hints:
Calculate O2 used
P?
Answer: BOD value = 140 mg/l
64. BOD vs. day?
• BOD is chemical procedure for determining DO needed by organism
in WW to break down OM at certain temperature and time.
• BOD takes time to go for completion cause rate of oxidation still
happen to the proportional of the remaining OM
• At 5 day oxidation of carbonaceous matter (CM) is 60-70%,
meanwhile at 20 day this CM could be oxidised to 95-99%.
• H/ever 20 days is long time to wait to determine the result. The 5-
day test still having the disadvantage, cause the WW treatment
system personnel cannot use it to make real-time OPERATION
ADJUSTMENT.
• At the same time, after 8-10 days nitrifying bacteria start using
O2 to convert ammonia nitrogen to nitrite then nitrate.
• T/fore we are interested only in first stage BOD/carbonaceous
BOD, and we chose 5 days test.
65. BOD vs. temperature?
• Temperature, directly affects the metabolic
rate of the bacteria.
• Incubation procedure at 20± 1°C provide
the perfect “controlled” environmental for
the bacteria to reproduce. It is often set up
(20 °C) as a robust surrogate/substitute of
the degree of the organic pollution in WW.
66. Question 8
The BOD5 of a wastewater is determined to
be 150 mg/L at 20oC. The k value is known
to be 0.23 per day. What would be the BOD8
be if the test were run at 15oC?
Hints:
Ultimate BOD
Correct k value (15oC)
Answer: y8 = 168 mg/l
