lecture 0. prerequisite information for wastewater treatment...
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Lecture 0. Prerequisite Information for Wastewater
Treatment Design
By
Husam Al-Najar
The Islamic University of Gaza- Civil Engineering Department
Advance wastewater treatment and design (WTEC 9320)
Source of Wastewater
Sources of
Wastewater Processing at
the Source Wastewater
Collection
Transmission
and Pumping Treatment Reuse/Disposal
Types of collection systems
Separate system
Sanitary system
Combined system
Both sanitary & storm water Storm water
Generally, most of the countries
recently preferring separate systems.
Sources of Wastewater
(Major Components)
1. Domestic: food, soap and detergents, bathroom (fecal and urine), and paper.
1.1. Gray water: Washing water from the kitchen, bathroom, laundry (without faeces and urine)
1.2. Black water: Water from flush toilet (faeces and urine with flush water)
1.3. Yellow water: Urine from separated toilets and urinals
1.4. Brown water: Black water without urine or yellow water
2. Commercial: bathroom and food from restaurants and other “stores.”
3. Industrial: highly variable, dependent on industry, controlled by pre-treatment
regulations.
4. Runoff from streets: sand and petroleum and tire residues (infiltration, not a direct
discharge).
Sewer: Sewers are under ground pipes or conduits which carry sewage to points of
disposal.
Sewage: The Liquid waste from a community is called sewage. Sewage is classified into
domestic and non-domestic sewage. The non domestic sewage is classified into industrial,
commercial, institutional and any other sewage that is not domestic.
Sewerage: The entire system used for collection, treatment and disposal of Liquid waste.
This includes pipes, manholes, and all structures used for the above mentioned purposes.
Infiltration: It is the water which inters the sewers from ground water through Leaks from
loose joints or cracks.
Inflow: It is the water which inters the sewers from the manholes during rainfall events.
DIFINITIONS
An Epidemiologist is a public health scientist, who is responsible for carrying out all useful and
effective activities needed for successful epidemiology practice
Endemic: المتوطنة األمراض a disease or pathogen present or usually prevalent in a given population or
geographic region at all times
Hyperendemic: equally endemic in all age groups of a population
Holoendemic: endemic in most of the children in a population, with the adults in the same population
being less often affected
Epidemic: وباء a disease occurring suddenly in numbers far exceeding those attributable to endemic
disease; occurring suddenly in numbers clearly in access of normal expectancy
Pandemic: a widespread epidemic distributed or occurring widely throughout a region, country,
continent, or globally
Epizootic: of, or related to a rapidly spreading and widely diffused disease affecting large numbers of
animals in a given region.
Incidence: rate of occurrence of an event; number of new cases of disease occurring over a specified
period of time; may be expressed per a known population size
Prevalence: number of cases of disease occurring within a population at any one given point in time
Outbreak: Sudden occurrence of an epidemic in relatively limited geographic area. While an outbreak is usually limited to a small focal area, an epidemic covers larger geographical areas & has more than one focal point.
Outbreak Epidemiology: Study of a disease cluster or epidemic in order to control or prevent further spread of the disease in the population.
Terms Associated with Disease Causation, etc.
Host: Any organism that can be infected by a pathogen under natural conditions
Agent: A factor such as a microorganism, chemical substance, or a form of radiation, the presence or absence of which (as in deficiency diseases) results in disease or more advanced disease.
Fomites واالشياء المالبس : Any inanimate ,.or nonpathogenic substance or material (e.g جمادsheets, surfaces of furniture, papers and so forth), exclusive of food, which may act as a vector for a pathogen
Vector: a carrier, especially the animal (usually an arthropod مفصلية حيوانات as an insect, spider) that transfers an infective agent from one host to another
Carrier – active: One who harbors a pathogenic organism for a clinically significant time and is able to pass the infection to others
Incubatory: The development of an infection from the time the pathogen enters the body until signs or symptoms االعراض first appear.
General Types of Water Pollutants
Causative
agent العامل
Reservoir المسبب للمرض
المصدر
Portal of
exit بوابة
الخروج
Mode of
transmission طريقة
انتقال
Portal of
entry بوابة
الدخول
Susceptible host
المضيف
Components of the infectious disease process- Chain of infection
سلسلة العدوى -مكونات عملية االصابة باألمراض المعدية
Modes of Transmission
Classification of transmission mechanism: It is known today that water-related diseases are
transmitted in four distinct mechanisms.
These include water-born, water-washed, water-based and water-related insect vector.
1. Water-born mechanism: this refers to the situation when the pathogen is in water which is
drunk by a person or an animal which may then become infected. Infections in this group
include cholera, typhoid, infectious hepatitis, diarrheas and dysenteries.
2. Water–washed mechanism: this includes diseases that can be significantly reduced if the
water volume used is increased. Thus quantity rather than quality is important in this
category. The relevance of water to these diseases is that it is an aid to hygiene and
cleanliness. This category includes types: Intestinal tract infection, such as diarrhea diseases
like cholera, bacillary dysentery. Thus are all faecal-oral in their transmission route and
therefore can be water-washed or water born. Skin or eyes infections: bacterial skin sepsis,
scabies, fungal infections, trachoma are examples.
3. Water-based mechanism: a water-based disease it one in which the pathogen spends a part of
its life cycle in a water snail or other aquatic animal.
All these diseases are due to infection by parasitic worms which depends on aquatic
intermediate host to complete their life cycle. Important examples are schistosomiasis, and
Guinea worm (Dranculus medinensis ).
4. Insect vector mechanism. In this case, insects breed in water or bite near water. Examples
include Malaria, Yellow fever, and onchocerciasis.
5. Chemical – related diseases
Due to the presence of harmful or fatal chemicals in water. This can be due to accidental
discharge of sufficient toxic matter into a water source.
Or due to long –term hazard due to exposure to minute concert concentrations, perhaps over
many years, example, lead piping and tanks in domestic plumbing.
Each day some 30000 people die from water–related diseases. In developing
countries 80 percent of all illness water– related (WHO)
Caused by polluted beach water
oGastroenteritis التهاب المعدة واألمعاء
oDiarrheal – 3 million death
oEncephalitis التهاب الدماغ
oStomach cramps and aches وآالم تقلصات في المعدة
oVomiting قيء
oHepatitis االلتهاب الكبدي
Infectious diseases caused by pathogens
oTyphoid
oGiardiasis
oAmoebiasis
oAscariasis
oHookworm
Liver damage and even cancer
Kidney damage
Neurological problems
Reproductive and endocrine damage التناسلي والغدد الصماء
Thyroid system disorders اضطرابات الغدة الدرقية
Why Treating Wastewater?
Domestic and industrial processes use and pollute water => wastewater
Minimize effects of discharge on environment
Remove pollutants for recycling and/or reuse of water
Objectives of Wastewater Treatment
• Ensure good water quality in natural environment
• Remove pollutants most efficiently and economically
• Avoid or minimize other environmental impacts like:
– solid disposal
– gas emission
– odour creation
– noise generation
How to Treat Wastewater????
Classification of Organisms:
The classification of macro- and microorganisms was based primarily on
physiological differences (from two to six major kingdoms proposed for categorizing
life)
In the 1970s techniques become available to examine the Nucleic acids, specially
ribosomal RNA (rRNA), which involved in translation the synthesis of proteins in
the living things.
Based on the analysis of 16s rRNA, Carl Woese identified an entirely new group of
organisms (The Archaea).
This lead to the modern classification of living things into a three-domain system.
(Archaea, Eucarya, and Bacteria).
Archaea are neither Bacteria nor Eukaryotes. Looked at another way, they are
Prokaryotes that are not Bacteria.
The three domain system
The three- domain tree of life
Breakdown (Catabolism)
Proteins to Amino Acids, Starch to Glucose
Synthesis (Anabolism)
Amino Acids to Proteins, Glucose to Starch
Metabolism = Anabolism + Catabolism
Microbial Planktonic Community
Plankton refers to the microbial communities suspended in the water column
Photoautotrophic organisms
within this community including
both eukaryotes (algae) and
prokaryotes (cyanobacteria) are
collectively referred to as
phytoplankton العوالق
Suspended heterotrophic
bacterial populations are
referred to as
bacterioplankton
protozoan
populations make
up the
zooplankton.
Ch
em
otro
pic
: Mic
roorg
anis
ms th
at
extra
ct e
nerg
y fro
m c
hem
ical re
actio
ns
(oxid
atio
n / re
ductio
n re
actio
ns).
Classification of microorganisms
energy and carbon source
Hete
rotro
ph
ic:
Mic
roorg
anis
ms th
at u
se
org
anic
matte
r as a
sourc
e o
f
carb
on
Au
totro
ph
ic: M
icro
org
anis
ms th
at u
se
CO
2 as a
carb
on s
ourc
e
Ph
oto
trop
hic
: Mic
roorg
anis
ms th
at re
ly o
nly
on th
e lig
ht fo
r energ
y
Types of -trophs
Type
Energy
C source
Example
Photoauto-
Sun
CO2
Purple بنف ي &
Green sulfur
bacteria
Photohetero-
Sun
Organic
Compounds
Purple & Green
Non-sulfur
bacteria
Chemoauto-
Chemical bonds
CO2
H, S, Fe, N
bacteria
Chemohetero-
Chemical bonds
Organic
Compounds
Most bacteria,
fungi, protozoa,
animals
Metabolism Electron donor (TEA) Carbon
source
Metabolism type
Respiration
Aerobic
Anaerobic
Fermentation
(Anaerobic only)
Organic compounds
(O2)
(NO3-, Fe3+, SO4
2-)
Organic compounds
(organic acid)
Organic
compounds
Chemohetrotroph
Psedomonas, Bacillus
Micrococcus, Geobacter, Desulfovibrio
Escherichia, Clostridium
Chemolithotrophy
Aerobic
Anaerobic
H2, S2-, NH4
-, Fe2+
(O2)
(NO3-)
CO2
Chemohetrotroph or
Chemolithotroph
Hydrogen bacteria,
Beggiaton
Planctomycetes
Phytosynthesis
Oxygenic
Anoxygenic
Light + H2O (NADP)
Light + H2S
(bacteriochlorophyll)
CO2
Photoautotroph
Cyanobacteria
Bacteria including purple sulfur bacteria
Phytohetrotrophy Light + H2S
(bacteriochlorophyll)
Organic
compounds
Photoheterotroph
Many purple nonsulfur bacteria purple sulfur bacteria
Metabolic Classification of Bacteria
The carbon cycle is dependent on autotrophic organisms that fix carbon
dioxide into organic carbon and hetrotrophic organisms that respire organic
carbon to carbon dioxide.
By their relation to oxygen
Classification of microorganisms
Key for respiration is the Terminal Electron Acceptor (TEA) that is used to deliver
electron to the electron transport chain.
• Under aerobic condition, the TEA is oxygen (38 ATP per glucose metabolism)
• Under anaerobic condition, an alternative TEA such as NO3-, Fe3+, SO4
2- or CO2 is
used. (2 ATP is less than aerobic except for NO3)
• Under facultative aerobes, either O2 or NO3 (Pseudomonas is example)
• Fermentation: is anaerobic process that uses only substrate level phosphorylation
with a net generation of 2 ATP per glucose.
No use for electron transport chain or for an external electron acceptor. Instead,
electrons are shunted among organic compounds usually ending in the production of
acids or alcohols and resulting in very small amount of energy.
• Bacterial growth is a complex process involving numerous anabolic and
catabolic reactions.
• Ultimately, these biosynathetic reactions result in cell division.
• In homogeneous rich culture medium, under ideal conditions, a cell can
divide in as little as 10 minutes.
• In contrast, it is found that the cell division may occur as slowly as once in
100 years in some subsurface terrestrial environments.
• Most of the information concerning the growth of microorganisms is the
result of controlled laboratory studies using pure culture.
• There are two approaches to the study of the growth under such
controlled conditions: Batch culture and Continuous culture.
Bacterial Growth
Binary Division
Growth in Batch culture (pure culture in a flask)
The growth of a single organism or group of organisms, called a
consortium, is evaluated using a defined medium to which a fixed amount
of substrate is added.
several distinct phases:
– Lag phase
– Exponential growth
– Stationary phase
- Death phase
It is difficult to extend our knowledge of growth under controlled laboratory
conditions to an understanding of growth in natural soil or water
environments, where enhanced level of complexity are encountered such
as:
1. Microbial interaction with organic and metal contaminants
2. Survival and growth or pathogens in the environment.
The number of cells present can be determined by viable plate counting (i.e., culturing),
direct microscopic counting, and/or turbidity (i.e., optical density)
Growth Phases
- Is thought to be due to the physiological adaptation of the cell to the cultural
condition.
- When microbes inoculated into fresh medium they do not start to grow
immediately (lag phase)
- Length of lag phase variable – depends on history of the culture and growth
conditions
– exponentially growing culture inoculated into same media, same growth
conditions – no lag phase
The Lag phase
– old culture, same media & conditions – lag phase because cells need to
replenish essential constituents to start growth & cell division cycle
– Cells damaged (heat, radiation, toxic chemicals) - lag phase as cells
repair damage
– Cells transferred from rich medium to poor culture medium, lag phase as
cells have to synthesize more enzymes etc. to enable synthesis of
macromolecules not present in poor culture medium.
- Each cell divides to form 2 cells; 2 cells divide to 2 cells; 2 cells divide to form 4 cells ……
- Rate of exponential growth influenced by environmental conditions (temperature,
composition of culture composition of culture medium) & genetic
characteristics of organism
The Exponential Phase
xdt
dx Where, x is the number or mass of cells (mass/volume), t is time and is
the specific growth rate constant (1/ time)
dtx
dxRearrange
x
x
t
o
dtx
dx
0
For x to be doubled: 2ox
x
te
2Therefore, Where t is the generation time
Bacteria Undergo Exponential Growth
• In a batch culture exponential growth cannot occur indefinitely
– Essential nutrients in medium is used up and/or some waste product of the organism builds
up to an inhibitory advice
– Exponential growth ceases = stationary phase
• In stationary phase – no net increase or decrease in cell number
• Many cell functions continue – energy metabolism, biosynthesis
• In some populations some slow growth may continue – some cells die and some grow – 2
processes balance out so no net change (cryptic growth ( نمو خفي
The Stationary phase
0dt
dx
• If incubation continues after stationary phase, cells may remain alive and
continue to metabolize or they may die = death phase
• In some cases cell death is accompanied by lysis
• Rate of cell death generally slower than that of exponential growth
The Death phase
xKdt
dxd Where Kd is the specific death rate
Effect of substrate concentration on growth
SK
S
s
m
m = maximum specific growth rate, T-1
S = concentration of the limiting substrate, mg/L
Ks = half saturation constant, mg/L
Monod equation, which developed by Jacques Monod in the 1940s:
The above equation is a hyperbolic function as shown on the figure below:
2
m
m
S
Ks Limiting Substrate (mg/l)
There are two constants in this equation, maximum specific growth
rate and Ks, the half saturation constant.
Both reflect intrinsic physiological properties of particular type of
microorganisms.
They also depend on substrate being utilized and temperature of growth.
Monod equation can be expressed in terms of cell number or cell mass (x)
as the following:
m
SK
Sx
dt
dx
s
m
SK
S
s
m
xdt
dx where
Thus,
The Monod equation has two limiting cases:
1. High substrate concentration: S >> Ks
• Under these condition, growth will occur at the maximum growth rate
2. Low substrate concentration: S << Ks
• This type of growth is typically found in batch flask systems at the end of the
growth curve as the substrate is nearly all consumed.
• It is also the typical growth that happened in the natural environment where
substrate and nutrients are limiting.
xdt
dxm
s
m
K
Sx
dt
dx
S, mg/L
µ,
1/h
r
µmax
S << KS mixed order S >> KS
Monod Growth Kinetics
• First-order region: S << KS, the equation can be approximated as = maxS / Ks
• Center region, Monod “mixed order” kinetics must be used
• Zero-order region: S >> KS, the equation can be approximated by = max
The Monod equation can also expressed as a function of substrate utilization given that
the growth is related to substrate utilization by constant called cell yield:
dt
dx
Ydt
ds 1
SK
SX
Ydt
ds
s
m1
where, Y= biomass yield = (g) biomass produced / (g) Substrate consumed
Cells Growth in Continuous Culture
Continuous culture: fresh nutrient medium is continually supplied to a well-stirred culture
and products and cells are simultaneously withdrawn.
At steady state, concentrations of cells, products and substrates are constant.
Growth in the environment
Oligotroph (k-Strategists) versus Copiotrophs (r-Strategists)
“The trouble with ecology is that you never know where to start because everything affects
everything else." Robert A. Heinlein, Farmer in the sky, 1950
These terms, r and K, are derived from standard ecological algebra, as
illustrated in the simple Verhulst equation of population dynamics:
where r is the growth rate of the population (N), and K is the carrying
capacity of its local environmental setting
)1(k
nrn
dt
dn
Oligotroph (k-Strategists):
is an organism that can live in a very low carbon concentration, less than one part
per million.
Most oligotrophs are bacteria, though archaean oligotrophs also exist.
Oligotrophs are characterized by slow growth, low rates of metabolism,
and generally low population density.
Long generation time.
They often use energy obtained from metabolism simply for cell maintenance.
oligotrophs may be found a wide range of environments including in deep
oceanic sediments, caves, glacial and polar ice, deep subsurface soil,
aquifers, and ocean water. An example of an oligotrophic bacteria,
Pelagibacter ubique.
Copiotrophs (r-Strategists):
organisms tend to be found in environments which are rich in nutrients,
particularly carbon, and are the opposite to oligotrophs which survive in
much lower carbon concentrations.
May exhibit high rates of metabolism and perhaps exponential growth for
short periods.
May be found in a dormant state (حالة السبات).
Dormant cells are often rounded and small in comparison with lab.
specimens
Dormant cells may become Viable But Non-Culturable (VBNC)
VBNC are thus difficult to culture because cell stress and damage.
In addition many environmental microbes are Viable But Difficult to Culture
(VBDC)
K strategists
Some examples
r strategists
Growth in the environment…. Continue
1. The lag phase:
The lag phase in the natural environment can be much longer than in the batch culture.
This is due to a combination of limited nutrient and suboptimal environmental conditions.
The second explanation for long lag period in the environmental samples is that the capacity
for degradation of an added carbon source may not initially be present within the existing
population. This situation may required a mutation or a gene transfer to introduce appropriate
degradative genes into a suitable population.
One of the first documented cases of gene transfer in soil was the transfer of the plasmid pJP4
from an introduced organism to the indigenous soil population. The plasmid transfer resulted in
rapid and complete degradation of the herbicide 2.4-D.
Once an environment has been exposed to a particular pesticide and developed a community
for its degradation, the disappearance of succeeding pesticide application will occur with
shorter lag periods. This phenomena called adaptation.
2. The Exponential phase:
In the environment the second phase of growth, exponential growth, occurs for only very
brief periods following addition of substrate.
Such substrate might be crop residues, vegetative litter, root residues or contaminants added
or spilled into the environment.
It is the copiotrophic cells, many of which are initially dormant.
Upon substrate addition, these dormant cells become physiologically active and briefly enter
the exponential phase until the substrate is utilized.
3. The Stationary and death phase:
Stationary phase in the laboratory (batch culture) is a period where there is
active cell growth that is matches by cell death.
In the environment the stationary phase is most likely of short duration if it
exist at all.
Recall that most cells never achieve an exponential phase because of
nutrient limitations and environmental stress.
Might they are in dormancy or in maintenance state.
Complicating the issue is the presence of bacteriophage that can
infect and lyse significant portions of the living bacterial community.
Mass balance of Growth:
Growth condition: when the substrate utilized to increase the cell mass.
Non growth condition: when the substrate and some nutrients is limiting, utilization of
the substrate occurs without production of new cells. The energy from substrate
utilization is used to meet the maintenance of the cell.
Cell yield coefficient (y) = g Cell mass production
g Substrate consumed
The value of cell yield is dependent on substrate being utilized.
Substrate Chemical formula Cell yield coefficient (y)
Pentachlorophenol C6HOCl5 0.05
Glucose C6H12O6 0.4
Octadecane C18H36 1.49
Example 1: A bacterial culture is grown using glucose as a source of carbon and energy.
The cell yield is 0.4. What percentage of glucose (substrate) carbon will be found as cell
mass and as CO2. Assume that you start with 1 mole glucose.
Solution:
Glucose = C6H12O6 molecular weight = 180 g/mol.
Cell mass = C5H7NO2 molecular weight = 113 g/mol.
Substrate mass x cell yield = cell mass production
180 x 0.4 = 72 g
Mol cell mass = 72 g cell mass / 113 g = 0.64 mol cell mass
In terms of carbon
Cell mass: 0.64 mol cell x (5 mol C/ mol cell mass) x (12 g/ mol C) = 38.4 g C
Substrate: 1 mol substrate x (6 mol C/ mol substrate) x (12 g/ mol C) = 72 g C
The percentage of substrate carbon found in the cell mass = 38.4 / 72 = 53%
Carbon release as CO2 = 100% - 53% = 47%
As microbes have evolved, standard catabolic pathways have developed for common
carbohydrate and protein containing substrate.
This translates into a cell yield of approximately 0.4 for sugar such as glucose.
Industrialization began in the late 1800s, many new molecules have been
manufactured for which there are no standard catabolic pathways.
Pentachlorophenol is an example to utilize it, a microbe must alter the chemical
structure to allow use of standard catabolic pathways. So microbes must expend
much energy to break the strong bond carbon-halogen. So little energy is left to
produce cells.
In contrast, Octadecane is a hydrocarbon found in petroleum products formed on
early earth, standard catabolic pathways exist for most petroleum compounds thus
the energy is stored to produce new cells.
Why there are such differences in cell yield for Pentachlorophenol,
Glucose and Octadecane substrates?
The carbon cycle, showing both aerobic and anaerobic contributions
The Nitrogen Cycle
Element breakdown % Dry mass of an E. coli Cell
Major elements
Carbon
Oxygen
Hydrogen
Nitrogen
Sulfur
Phosphorus
50
20
8
14
1
3
Minor elements
Potassium
Calcium
Magnesium
Chlorine
Iron
2
0.05
0.05
0.05
0.2
Trace elements
Manganese
Molybdenum
Cobalt
Copper
Zink
All trace elements combined
comprise 0.3% of dry weight of cell
Chemical composition of an E. coli Cell.
59
Wastewater Treatment Plant
Acinetobacter: (-) Phosphorus removal from wastewater
Azotobacter: (-) Nitrogen fixation
Bdellovibrio: (-) attack pathogenic bacteria
Desulfovibrio: (-) sulfate reduction in wastewater
Enterobacter aerogenes: (-) indicator organism
Escherichia coli: (-) indicator organism
Methanobacterium, Methanosarcina : (-/+) methane production
Nitrobacter, Nitrosomonas : (-) Ammonium oxidation
Pseudomonas: (-) Nitrate removal from wastewater
Rhizobium: (-) Nitrogen fixation
Streptococcus: (+) lactic acid production
Thiobacillus: (-) sulfur oxidizer
List of Bacteria should be known for wastewater treatment engineers