Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH 1
EAP582/4: Wastewater Engineering
Wastewater Treatment Plant Principles' and Design
Dr. ABU AHMED MOKAMMEL HAQUEDr. ABU AHMED MOKAMMEL HAQUESchool of Civil Engineering,
Engineering Campus,Universiti Sains Malaysia
14300 Nibong Tebal, P. Pinang,Malaysia.
E-mail: [email protected], 2010
3
AAMH
Pre-Requisite Knowledge and/or Skills
Basic Principles of Environmental Engineering
Basic Principles of Environmental Fluid Mechanics
Mass Balance Techniques
Basic Organic and Inorganic Chemistry
Understanding of Environmental Engineering unit Processes
Basic Computer Spreadsheet Application
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH 3
OutlineOutlineObjectives
Introduction- Plant Classifications (Aerobic, Anaerobic, Fixed Media,
Suspended Culture etc)
Type of Treatments- Primary, Secondary, Tertiary (Management Aspect,
Biological oxidation, Kinetics of BOD etc)- Design Aspects- Physical & Chemical Plant (Screen, Grit
Removal, Comminutor, Skimming & Equalization Tanks, Sedimentation Tank, Coagulation & flocculations)
- Design of biological Plant (Activated Sludge, RBC, Anaerobic Digester etc)
Advance Wastewater Treatment
Reclamation and Reuse
AAMH
AAMH Teaching Plan
Revision (Sep 06/10)W5
Wastewater Reclamation & Reuse (Sep 01/10)W4
Wastewater Reclamation & Reuse (Aug 29/10)W4
Advance Wastewater Treatment (Aug 25/10)W3
Type of Wastewater Treatments (Aug 23/10)W3
Type of Wastewater Treatments (Aug 18/10)W2
Type of Wastewater Treatments (Aug 16/10)W2
Introduction – Concept, Source, Objectives, Plant Classification (Aug 11/10)
W1
Introduction – Concept, Sources, Objectives, Plant Classification (Aug 09/10)
W1
TOPICSSECTION
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Primary Treatment Layout Complete
COMPLETE
AAMH
Biological Treatment Processes
WastewaterBiological ProcessesTreatment ProcessesApplicationsResearch Activities
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment ProcessesWastewaterWastewater• Domestic Wastewater• Commercial Wastewater• Industrial Wastewater
Present State of Wastewaterover 80 % - untreated in Asian mega cities
major components- COD = 250-1000 mg/LTotal N = 20-90 mg/LTotal P = 4-15 mg/L
effects of discharging into natural receiving bodies
oxygen demand by carbon and nitrogen
AAMH
Biological Treatment Processes
Starch industry wastewatermajor component-
COD = 10,000-20,000 mg/L
Effects of discharging into natural receiving bodies (Rivers, lake, Sea etc)
- 20 m3/ton of starch- high COD - high suspended solids- cyanide exposure
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
Starch industry wastewaterFactory with 300 T/d of starchWastewater generation 6000 m3/day COD 14,000 mg/LPopulation equivalent 1000,000
•Present treatment method: Anaerobic ponds •Typical loading rates: around 800-1000kg
COD /ha/d•Area requirement: 100 ha
AAMH
Biological Treatment Processes
Strength of Wastewater• Waste-water originates predominantly
from water usage by residences, commercialand industrial establishments, together with groundwater, surface water and storm water.
• Strength of wastewater depends on: the types and source of wastewater generation;concentration level of pollutant constituents;and their toxicity level on surrounding environment.
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
6 – 12 mg/LTotal Phosphorus (TP)
26 – 75 mg/LTotal Nitrogen (TN)
< 1 mg/LNitrate-Nitrogen, NO3-N
4 – 13 mg/LAmmonium-Nitrogen, NH4-N
106 – 108CFU/100mLFecal Coliform Bacteria
108 – 1010CFU/100mLTotal Coliform Bacteria
6 – 9 N/ApH
155 – 286 mg/LBOD5
155 – 330 mg/LTotal Suspended Solids, TSS
Range of Concentration UnitComponents
Raw sewage pollutant constituent’s characteristics
AAMH
Biological Treatment ProcessesRaw Leachate pollutant constituent’s characteristics
54.6746.67mg/LPhosphate ((PO43-)
2.671.33mg/LNitrate Nitrogen(NO3–N)
46.736.7mg/LNitrite Nitrogen(NO2–N)
2387.51800mg/LAmmonia Nitrogen (NH4–N)
1771.871520.5mg/LTKN
338184mg/LBOD
2403.31773mg/LCOD
490366mg/LSuspended Solid
41533527.5Pt.Co*Color
7.897.12N/ApH
MaximumMinimumUnitParameter
* Platinum-Cobalt Scale (Pt.Co scale or APHA-Hazen Scale )
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
Biological Processes .. .. .. .. Aim: any form of life- ‘ survive & multiply ’
Need for energy & organic molecules as building blocks
Made of C, H, O, N, S, P and trace elements
Cell: derives energy from oxidation of reduced food sources (carbohydrate, protein & fats)
AAMH
Biological Treatment Processes
MicroorganismsMicroorganisms
Classification: Heterotrophic- obtain energy from oxidation of organic matter (Organic Carbon)
Autotrophic- obtain energy from oxidation of inorganic matter (CO2, NH4, H+ )
Phototrophic- obtain energy from sunlight
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
Biochemical PathwaysBiochemical PathwaysOxidation of organic molecules inside the cell can occur aerobic or anaerobic manner
Generalized pathways for aerobic & anaerobic fermentation
AAMH
Biological Treatment ProcessesGlucose
EMP Pathway
Pyruvic Acid
ADP ATP
Energy
Lactic Acid TCA Cycle H+ Respiration H2O
CO2 O2http://dwb4.unl.edu/Chem/CHEM869P/CHEM869PLinks/www.bact.wisc.edu/mi
crotextbook/metabolism/Fermentation.html Embden-Meyerhoff-Parnas Pathway (EMP)
TCA = Tri-Carboxylic Acid cycleATP = Adenosine Tri-PhosphateADP = Adenosine Di-PhosphateNAD+ = Nicotinamide adenine dinucleotide
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
aerobic pathways contains-EMP pathways, TCA cycle, respiration
anaerobic pathways contains-EMP pathways
released energy stored as ATP molecules
excess food is stored as Glycogen
C6H12O6 + 6O2 +38 ADP + 38 Pi 6 CO2 +38 ATP + 44 H2O
AAMH
Biological Treatment Processes
Biological growthConcept of Microbiology
- BOD exertion
- Exponential growth (batch)
- Monod kinetics
- Haldane kinetics
under toxic conditions
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Oxygen Demand (BOD)
Biological/Biochemical Oxygen DemandBiological/Biochemical Oxygen Demand ((BOD):the amount of oxygen used by microorganism in the oxidation of organic matter (ammonia, nitrite) in water or wastewater.
Any ammonia present in a waste stream may also be oxidized by nitrifying bacteria in a process called nitrification. Nitrification also demands oxygen, which is referred to as nitrogenous BOD (NBOD). A general equation for the overall nitrification process is shown below.
OXIDATIONammonia +oxygen +carbon dioxide +nitrifying bacteria
nitrate + water + new cells + energy
AAMH
Biological Oxygen Demand (BOD)Biological/Biochemical Oxygen Demand (BOD)Biological/Biochemical Oxygen Demand (BOD)The Oxygen (O2) demand by microbes during the degradation of Organic matter (OM) to CO2 + H2O under aerobic conditions at a particular temperature and incubation period.
Standard BOD BOD on 5 days at 20oC which indicate pollution strength of wastewater or waste stream.
OM + DO (Dissolve Oxygen) + Heterotrophic Microbes CO2 + H2O + More cells + Energy
BOD Test UsedBOD Test Used• To determine the polluting strength of waste stream.
• To determine the size and efficiency of waste treatment facilities.
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological CharacteristicsBOD Test
Provide microbes with initial DO and measured DO consumption after 5 days in a close environmentAlso provide nutrients for microbes growth (Except domestic wastewater)BOD = [(DO)i – (DO)f], Saturation level of normal (DO)i = 9 mg/L @ 20oC
• is conducted in air tight bottles to prevent reaeration of samples.• Due to limited solubility of oxygen in water (about 9 mg/L at
20oC) concentrated waste must be diluted to ensure DO viability throughout the test period.
• The samples should have adequate amount of microorganism; if not then seeding is required
• Presence of nutrients and absence of toxic substance is ensured.• Samples are incubated for 5 days at 20oC.• DO of the samples is measured befor and after incubation to
calculate the BOD.
AAMH
Biological CharacteristicsCalculation:Calculation: BOD TestBOD TestFor domestic Wastewater ---- Do, Microorganism, Nutrient presentFor Industrial Wastewater --- Add Seed Microorganism (Domestic
Settle Sewage content 106 – 107 MO/mL)Case 1Case 1(DO)f = 5 mg/L; BOD = (DO)saturation - (DO)f = (9 – 5)*1 = 4 mg/LCase 2Case 2(DO)f = 0 mg/L; BOD = (DO)saturation - (DO)f = (9 – 0)*1 = 9 mg/L;
Invalid Result, BOD cannot be determined, therefore need the dilution of the waste sample --- Test to be valid upto (DO)f should not < 1 mg/L
Case 3Case 3(DO)f = 8.8 mg/L; BOD = (DO)saturation - (DO)f = (9 – 8.8)*1 = 0.2
mg/L; Invalid Result, Test to be valid (DO) consumption ≥ 2.0 mg/L
Conditions Conditions -- ◙◙ Provide DO ( If not Dilute the Sample) ◙◙ MO (If not add seed MO from domestic settle sewage) ◙◙ Nutrient ◙◙ Dilution Dilution (DO) consumed 5 days ≥ 2.0 mg/L and (DO)f ≥ 1 mg/L
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Oxygen Demand (BOD)
Standard BOD bottles in the lab
When dilution water is not seeded:
When dilution water is seeded;-
Where :
D1 = DO of diluted sample immediately after preparation, mg/L
D2 = DO of dilute sample after 5 day incubation, mg/L
B1 = DO of seed control before incubation mg/LB2 = DO of seed control after incubation mg/Lf = fraction of seeded dilution water volume in sample to volume of seeded dilution in seed control.P= fraction of wastewater sample volume to total combined volume
AAMH
Biological Oxygen Demand (BOD)
Question : An unseeded BOD test was conducted on domestic wastewater 20mL of the sample was diluted to 1L by aerated dilution water. Calculated the BOD of the sample if the initial and 5 days DO were 7.6 and 3.7 mg/L respectively.
EXAMPLE:
Solution
D1 = 7.6 mg/LD2= 3.7mg/L
P = 20 /100
= 0.02
= (7.6- 3.7)/ 0.02= 195 mg/L
Fraction of water sample
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Oxygen Demand (BOD)Question : The following information was obtained from a seeded 5 days BOD test on a wastewater sample. Dilution water was prepared with a seed dilution of 1 in 200 and the BOD bottles were prepared by diluting the wastewater sample to 1 in 200. The initial DO of diluted sample was 8.5 mg/L and the final 5 day BOD was 2.2 mg/L. The corresponding initial and final DO of the seed dilution water was 8.8 and 7.6 mg/L respectively. Calculate the BOD5 of the wastewater sample.
SolutionD1 =8.5mg/L B1= 8.8mg/LD2 = 2.2 mg/L B2= 7.6 mg/L
P = 1 / 200 = 5 x 10‐3
f = ( 200‐ 1)/ 200 = 0.995
1021 mg/L
AAMH
Biological Oxygen Demand (BOD)
Wastewater Type
BOD (mg/L) (1)
Wastewater Volume
(L/unit) (2)
BOD Load (g/unit) (3)
Cow 450-4330 45 - 136 182
Pig 1275 - 13260 11 - 23 114
Chicken & Duck 8500 - 40000 0.2 7 - 15
Sewage 250 - 400 227 68
Wastewater concentration differs depending on its source
BOD Load = (3) = (1) * (2)
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Oxygen Demand (BOD)
Wastewater type BOD load per day (g/day) (1)
TKN load per day (g/day) (2)
Sewage 55 -
Cow 498 222
Buffalo 347 107
Sheep 102 22
Pig 137 23
BOD load composition and TKN load per day for different wastewater
(1) = BOD (g/L) * Flow rate (L/unit.day)
(2) = TKN (g/L) * Flow rate (L/unit.day)
AAMH
Biological Oxygen Demand (BOD)E.g. 1.1 :
Calculate BOD value for a wastewater from 1000 persons with total flow rate of 225 m3/day. Assume BOD rate is 55 gram/person.day.
Solution :A person produces 55 gram BOD/person.day, therefore for 1000 persons, the total BOD produced is
= (1000 persons) (55 gram/person.day)= 55 000 gram/day
Flow rate, Q = 225 m3/day, therefore by dividing 55 000 g/day with flow rate Q, we can get BOD value as;
BOD = 55 000 gram/day225 m3/day
= 244.44 mg/L= 244 mg/L (BOD is written in round number)
What will be the load -------- Population Equivalent???
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Oxygen Demand (BOD)Question:
If the BOD5 for wastewater is 300 mg/L and the total water usage is 200 liter/unit. How much the BOD5 load for this wastewater?
Solution :
BOD5 load = BOD5 × unit usage = 0.3 g/L × 200 L/unit= 60 g/unit
If total population are 10,000 then what will be the load -------- Population Equivalent???
AAMH
1st Order Biological Oxygen Demand (BOD)
Modeling of BOD Reaction:The rate of BOD oxidation (“exertion”) is modeled based on the assumption that the amount of organic material remaining at any time “t” is governed by a FIRST-ORDER Kinetic function as given below:
dBODr/dt = - k1BODr
Integrating betn the limits of UBOD and BODt and t =0 and t= t yields [BODr = UBOD(e-k
1t)]
WhereBODr = Amount of waste remaining at time t (days) expressed in oxygen equivalents, mg/LK1 = First-order reaction rate constant, 1/dUBOD = total or ultimate carbonaceous BOD, mg/Lt = time, d
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
1st Order of BODModeling of BOD Reaction:
Therefore, BOD exerted upto t is given byBODt = UBOD – BODr = UBOD – UBOD(e-k
1t) = UBOD (1 – e-k
1t)
Calculation of BODDetermine the 1-day BOD and Ultimate first-stage BOD for a
wastewater whose 5-day 20oC BOD is 200 mg/L. The reaction constant k(base e) = 0.23/day. What would have been the 5 day BOD if the test had been conducted at 25oC.
Solve?????
AAMH
1st Order Kinetics of BODCalculation:Calculation: Total OM in the systemTotal OM in the system OROR Kinetic of BODKinetic of BODMicrobes consume OM as a function of time (t), No instantaneous consumption of DOBOD excretion OM consumption followed FIRST ORDER EQUATION dL/dt α L ; Where L is the O2 ≅ OM ; Therefore, dL/dt = -kt (-ve sign, OM decreases with time)
tko eLL −=
BOD Rate Constant which explained the property of MO present in the system
k –
BOD EXERTED
Lo – is ultimate O2 demand (UBOD), constant value for a given OM & Heterogeneous microbial Seedk – Speed of Reaction
∫∫ −= oo t
t
L
Lkdt
LdL
tkLL
o
−=⎟⎟⎠
⎞⎜⎜⎝
⎛ln
If Three samples have the same Lo value but different k value k1> k2 > k3
)1( tko
tkoo
o
eLY
eLLY
LLY
−
−
−=
−=
−=
Ultimate O2 demand , O2 for the oxidation of the initial OMLo
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological CharacteristicsUltimate BOD
BOD exerted from time 0 to t
BOD remaining at time, t
Lo
0
Yt, Lt Yt
Lt
Time, t
Lo- Yt
K = 0.1-0.5 d-1 ; depends on temperature.KT = Rate constant at ToCK20= Rate constant at 20oCӨ = constant, generally taken as 1.047
BOD curve
KT= K 20 Ө T-20 Van Hoff Arrhenius Equation
AAMH
Biological Characteristics
Why 5 days incubation70 – 80% BOD – Lo is exerted in 5 daysNitrification occurs after 5 days
O2NH3 + O2 --- NO2
- --- NO3-
One N atom ≅ 1.5 O2
OM -- CO2 + H2ONow a day BOD on 3 days at 28oC Oxidation take place faster and experimentation completed within short time
•S1 is more easily biodegradable than S2 and S3
• S1 is simple organic matter [Carbohydrate -(C·H2O)n]
• S2 may be Protein (polypeptides – amino acids)
• S3 may be lipid (very resistant for oxidation)
• k depends on Temperature
• kT = k20 (θ)T – 20; θ = 1.047; Constant for Temp. range (20 – 30oC); Micro-organism works high temperature
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
Exponential growth
XdtdxX
dtdx µα =>>>
Log
No.
of C
ells
TimeLa
g ph
ase
Log
gro
wth
pha
se
Stat
iona
ry p
hase
Dea
th p
hase
AAMH
Biological Treatment Processes
Monod kinetics
SKS
S +=
.maxµµ
Substrate Concentration (S)
Spec
ific
grow
th ra
te (
µ)
Max. rateµm
µm/2
ks
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
Haldane kinetics(under toxic conditions)
is K
iSSKS
.max++
= µµ
Substrate Concentration (S)
Spec
ific
grow
th ra
te (
µ) i
http://www.graphpad.com/curvefit/introduction63.htm
AAMH
Biological Treatment Processes
Application1. Carbonaceous removal - aerobic
- anaerobic
2. Nitrogen removal - nitrification- denitrification
3. Sulfide removal - anaerobic SO4 reduction- aerobic HS- oxidation
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Carbonaceous Removal
Aerobic- oxidation
bacteriaCHONS + O2 + Nutrients CO2 + NH3 + C5H7NO2
(organic matter) (new bacterial cells)
+ other end products
- Endogenous respirationbacteria
C5H7NO2 + 5O2 5CO2 + 2H2O + NH3 + energy(cells)
AAMH
Biological Carbonaceous RemovalIn BOD 5 days incubation70 – 80% BOD – Lo is exerted in 5 days. Nitrification occurs after 5 days
O2NH3 + O2 --- NO2- --- NO3-One N atom ≅ 1.5 O2
OM -- CO2 + H2ONow a day BOD on 3 days at 28oC Oxidation take place faster and experimentation completed within short time
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Treatment Processes
Anaerobic
AAMH
Biological Treatment Processes
Hydrolysis
Acidogenesis
Methenogenesis
Complex Organics
Intermediates Propionate
H2Acetate
CH4
20% 5%
60% 15%
35% 10% 13%17%
15%
72% 28%
100%
Anaerobic
Schematic of the Anaerobic ProcessReturn 50
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Nitrogen Removal
Nitrification-Energy
NitrosomonasNH4
+ + 1.5 O2 NO2- + H2O + 2 H+ + (240-350 kJ) (1)
NitrobacterNO2
- + 0.5 O2 NO3- + (65-90 kJ) (2)
-AssimilationNitrosomonas
15 CO2 + 13 NH4+ 10 NO2
- + 3 C5H7NO2 + 23 H+ +4 H2O (3)Nitrobacter
5 CO2 + NH4+ +10 NO2
- +2 H2O 10 NO3- + C5H7NO2 + H+ (4)
- Overall reaction
NH4+ +1.83 O2 + 1.98 H CO3
- 0.021 C5H7NO2 + 0.98 NO3- + 1.04 1H2O + 1.88H2CO3
AAMH
Biological Nitrogen Removal
Factors Affecting Nitrification* temperature * substrate concentration
* dissolved oxygen * pH
* toxic and inhibitory substances
( )[ ])2.7(83.01)15(095.0
4
4 pHeDOK
DONNHK
NNH T
ONm −−⎥
⎦
⎤⎢⎣
⎡+
⋅⎥⎦
⎤⎢⎣
⎡−+
−= −µµ
Factors Affecting Denitrification* temperature * dissolved oxygen
* pH
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Nitrogen Removal
Denitrification* Assimilatory denitrification- reduction of nitrate to ammonium by microorganism for protein synthesis
* Dissimilatory denitrification- reduction of nitrate to gaseous nitrogen by microorganism- nitrate is used instead of oxygen as terminal electron acceptor- considered an anoxic process occurring in the presence of nitrate and the absence of molecular oxygen- the process proceeds through a series of four steps
NO NO NO N O N 3-
2-
2 2⎯→⎯ ⎯→⎯ ⎯→⎯ ⎯→⎯
AAMH
Biological Nitrogen Removal
Denitrification
* Heterotrophic denitrification
- denitrifiers require reduced carbon source for energy and cell synthesis
- denitrifiers can use variety of organic carbon source -methanol, ethanol and acetic acid
NO + 1.08CH OH + H 0.065C H O N 0.47N 0.76CO 2.44H O3-
3+
5 7 2 2 2 2⎯→⎯ + + +
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Biological Sulfate Removal
* Sulfate Removal Cycle
anaerobic
SO4-- HS - S 0 (O2 deficient)
(O2 excess)
AAMH
Biological Treatment Processes
Pond treatment
Activated Sludge Process
Bio-film Process
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Anaerobic Ponds- no biomass recirculation- high HRT- high land area- O2 transfer limitations- inadequate mixing- excess loading
(anaerobic condition-H2S generation)
AAMH
BTP – Pond Treatment
- no biomass recirculation- high HRT (MWW 1-3 d; IWW >20 d)- high land area- O2 transfer limitations- inadequate mixing- excess loading
(anaerobic condition-H2S generation)- Temp. ((hydrolysis, acidogenesis, acetogenesis and methanogenesis) [S-42]- TSS >> 50-70%- BOD >>High Temp >>30 – 75%
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond TreatmentMechanism
• After hydrolysis of particulate organic matter, fermenting bacteria convert the readily biodegradable organic substrate into volatile fatty acids (VFAs).
• Higher VFAs are further decomposed, mainly into acetic acid and H2, the typical substrate for the strict anaerobic methanogens.
• Effective anaerobic pond management has to avoid VFA accumulation and the associated drop in pH as methanogens are very sensitive to pH values less than 4-5. [S-42]
AAMH
BTP – Pond Treatment
The overall anaerobic decomposition of organic matter can be expressed by the following equation :
Preliminary Treatment- Coarse Screening (large pieces of wood, plastics, can, bottles): to avoid clog pipes/channels- Grit Chamber/Channel – to prevent accumulation of grit to pond and reduce the active pond volume and reduce desludging frequency
3242 83
48283
48243
24dNHCOdbanCHdbanOHdbanNOHC dban +⎟
⎠⎞
⎜⎝⎛ +−−+⎟
⎠⎞
⎜⎝⎛ +−+→⎟
⎠⎞
⎜⎝⎛ +−−+
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Design Parameters:
whereVan = Pond Volume (m3)A = Surface Area (m2)D = Aver. Pond Depth (m)BODin = Influent BOD Concentration (kgBOD/m3)Q = Flow Rate (m3/day) OR Population Equivalentλv = Volumetric Organic Loading Rate (kgBOD/m3/day)
v
inan
QBODDAV
λ*
* ==
AAMH
BTP – Pond Treatment
•Design Volumetric Organic Loading Rates for Anaerobic Ponds as a Function of the monthly average Temperature (Mara & Pearson, 1986)
.)( averv TF=λ
300.30>20
2*Temp + 200.02*Temp. – 0.1010 – 20
400.1< 10
BOD Removal (%)Volumetric Organic Loading
(λv = kgBOD/m3/day
Min. Month-Aver. Air Temp. (oC)
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Operational Period of an Anaerobic Pond until Desludging is required:
Where,Van = Pond Volume (m3)n = Operational period betn Desludging (years)PE = no. Population EquivalentSAR = Sludge accumulation Rate, Typically 0.04 m3/PE/year[For a BOD production of 40 g/PE/day and at 20oC >> requires
0.13 m3 pond volume per PE, then n = 1.1 year]
SARPEV
n an
*1*
3=
AAMH
BTP – Pond Treatment
Facultative PondsFurther Removal of BOD, nutrients & Pathogen.Depth: usually 1.5 – 2.5 mHRT : varies betn 5 – 30 daysMost effective for MWWTFiltered Effluent BOD = 20 – 60 mg/L and TSS
level = 30 – 150 mg/LAnaerobic Ponds >> Facultative Ponds >>
Maturation Ponds
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
•Design based on Algae-Oxygen Production –[Theoretical]
•Design based on First-order BOD degradation constants and ideal flow conditions (CSTR -Continuous Stirred-Tank Reactor or PFR –Plug Flow Reactor) [Semi-Empirical]
•Design based on the dispersed-flow model [Semi-Empirical]
•Design based on surface BOD load [Empirical]
AAMH
BTP – Pond Treatment
(1) Design Mechanism
1. Oxidation>> OM>> Aerobic & Facultative Bacteria2. Balance O2 input by Photosynthetic algae & surface
reaeration to the O2 demand exerted by OM.3. Symbiosis of Algae – Bacteria 4. Relation of Algae growth – O2 production
Aerobic Zone
Facultative Zone
Anaerobic Zone
Algae
Light
O2
BacteriaOM
CO2, NH4+, PO4
+
New Cell
Symbiosis
2164518010634322 2
3091690106 OPNOHCLightPONOOHCO +→++++ −−
C106H180O45N16P Represent Algae Biomass. To sustain algae growth & Photosynthesis need supply of macro-nutrients (N, P, K). Required BOD/N/P ratio = 100/5/1 is generally recommended to safe the basic need
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
(2) Design Mechanism[accumulation] = [in] - [out] + [generation] - [consumption]
BOD accumulation =BOD influent – BOD effluent – BOD degraded
Si, Se = Ultimate soluble influent and effluent BOD respectively, mg/LQ = Flow Rate (m3/day)V =Volume of the Pond (m3)KT = First order reaction co-efficient of BOD HRT = V/Q = Hydraulic retention time in the Pond (day)Pond with high L/W ratio (>10) behave as Plug-Flow reactor.First-order BOD degradation the effluent BOD (soluble is given by):
increase due to logarithmic increase in PFR.
VSKQSQS eTei −= 1.1
+=≥+=
HRTKS
StKSS
T
ieT
e
i
KT= K 20 Ө T-20
HRTKie
TeSS −=
AAMH
BTP – Pond Treatment
(3) Design Mechanism: Dispersed-Flow model
Where n is the model parameter (numbers of mixers in series), If one pond equals one mixer, n> 3 or 4 no BOD removal .
(4) Design Mechanism: EmpiricalWehner-Wilhem model
KT = First-order Reaction coefficient (day-1)
n
T
ie
nHRTK
SS
⎟⎠⎞
⎜⎝⎛ +
=
1
( ) )2/(2)2/(2
21
)1(14
δδ
δ
aai
e
eaeaae
SS
−−−+= δHRTKa T41+=
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond TreatmentSubstrate removal according to the dispersed flow model of
Wehner-Wilhem (Thirumurthi, 1969)
AAMH
BTP – Pond Treatment
Various empirical design equationsdeveloped from full-scale performance of facultative ponds (Ellis and Rodrigues, 1995)
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
BOD removal rates λr (kg BOD/ha/day) of facultative ponds as function of the applied organic surface loading rates for various regions (Ellis and Rodrigues, 1995)
AAMH
BTP – Pond TreatmentOxygen balance in Facultative Ponds
( ) ( ) [ ] [ ] [ ]{ }BODinBODBinNNNdodresphotosat
in CCQaCCQarrrCCKACCQdtdCV −−−−−−+−+−= ..
Where, V = pond volume, (m3); C = DO concentration (mg/L); Cin = DO concentration in Influent (mg/L); t = Time (day); Q = Flow Rate (m3/day); A = pond surface area (m2); K = reaeration mass transfer co-efficient (m/day) CSat = saturation DO concentration (mg/L); rphoto = rate of DO generation by algae photosynthesis (g/m2/day); rres = rate of DO consumption by respiration (g/m2/day); rdod = rate of DO consumption by plant decomposition (g/m2/day); aN = stoichiometric co-efficient for NH4-N oxygen demand; aB = stoichiometric co-efficient for BOD; CN = Concentration ammonium nitrogen (mg/L); CBOD = concentration of BOD (mg/L)
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment• In the above O2 Balance equation some parameters are not
available Like as aN and aB parameters were estimated for a surface flow wetland to be 4.5 and 1.5 respectively (Kadlec and Knight, 1996).
• The physical reaeration of a pond through the open water surface is the combined effect of molecular diffusion and the vertical mixing of the pond by wind. In addition rainfall increases mixing and rainwater carries DO. The reaeration mass-transfer co-efficient K for situations without wind was estimated by O’Connor and Dobbins as:
Where, D = molecular diffusivity of oxygen in water (m2/day)h = water depth (m)U = Water Speed /(Travel Velocity) (m/day)
hDUK =
AAMH
BTP – Pond Treatment• In Facultative/Maturation Ponds the solar radiation is
absorbed by algae present in the water column and the energy is used for photosynthesis in which process Carbon-dioxide (CO2) is consumed and oxygen (O2) is produced. Simultaneously algae consume O2 by respiration. Arceivala (1986) predicted the Net Oxygen production (rphoto – rres) by algae photosynthesis as:
Where, Y = Net Algal Bio-mass yield (mg/cm2/day)S = Average visible radiation (cal/cm2/day)η = Light conversion efficiency (0.06)h = Specific chemical energy of Algae biomass (cal/mg)
hSY η3.1=
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Maturation Ponds (MP)- Shallow ponds, algal biomass is maintained- During daytime large amount of oxygen are produced- Aerobic in nature, depth 1 – 1.5 m- F. Coliform and virus die-off rates very high (probably
reached at 3 to 4 log units)- Cysts and Ova of intestinal parasites are densities
increase and settle on pond bottom and eventually die-off.
- BOD removal is slower, also degradable material is less and already consumed in Facultative ponds.
- Experimental results showed that there was no correlation betn BOD removal in Maturation Ponds with Temperature or retention time (Mara et al., 1990 and 1992).
AAMH
BTP – Pond Treatment
- High amount of algal biomass in the effluent quality represents a high Suspended Matter (SM) concentration, may be exceed Final effluent Guidelines.
- Normally O2 demand exerted by these SM is around 0.5 – 0.6 mg BOD5/mg Algal TSS (Arceivala, 1986).
- If MP are designed to optimize algal protein, commonly called HRAR (High Rate Algal Ponds
- Major application of MP is to polish or upgrade facultative pond effluents and achieve substantial reductions to allow safe use of the effluents in Agriculture or Aquaculture.
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Removal of Pathogenic Micro-Organism-Pathogen removal occurs in anaerobic, facultative and maturation ponds, However, Only MP are designed on the basis of required removal rates of pathogens.
105
104
103
103
103
102
104
103
103
1011110
1/L1/L1/L1/L1/L1/L1/L
Enteric virusesSalmonellaeCholera vibrioHookworm ovaAscaris ovaSchistosome ovaEntamoeba histolyica cysts
Pathogens
2 × 108
103105
11/100 mL1/L
Faecal ColiformsHelminth Eggs
Indicators
MaxMin
RangeUnitsIndicators/Pathogen
Common concentration of
pathogens in municipal sewage
Pathogen present in municipal
sewage
AAMH
BTP – Pond TreatmentRemoval of Helminth eggs and ProtozoaBoth are removed by sedimentation. Therefore, their removal are mostly affected by Hydraulic Retention Time (HRT) as following formula:
Where, R = % Removal
[ ]20085.0*49.0*41.01*100 HRTHRTeR +−−=
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Light attenuation in algae pond water
AAMH
BTP – Pond Treatment
Photo-Oxidation Process (Curtis et al., 1992)
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
Modeling of faecal coliform (FC) decayModeling of FC decay is aimed at predicting removal efficiencies in
existing pond systems or at the design of new systems. The model usually comprises a hydraulic flow pattern model and an equation to predict the FC decay coefficient for first order decay:
Where, FC = Count (no./mL); t = Time (days); Kd = First order decay coefficient (day-1)
For a complete Mixed Pond, Above Equation changes into:
Where Ni and Ne are the number of faecal coliform in influent and effluent, respectively and θ is the total retention time.
daymLnotKdtdN
d /100/.*−=
θdi
e
KNN
+=
11
AAMH
BTP – Pond Treatment
Design of Maturation Ponds- Calculation depends on # of ponds and Hydraulic
Retention Time per pond.- Assume Depth (1 -1.5 m), - Length: width varies 3 to 10.- Considered as completely mixed pond like as CSTR
Reactor- For n numbers of MP in series with completely mixed
ponds with total retention time θ:
n
do
t
nK
NN
⎟⎠⎞
⎜⎝⎛ +
=θ1
1
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Pond Treatment
The Kd for faecal coliforms is taken as 2.6/day at 20oC. The temperature dependence of Kdover 5 – 30oC has been determined by Marais (1974). The value of Kd can be corrected for other prevailing Sewage temperature according to:
Where Kd(T) is the die off rate constant at ToC . In practice Maturation Ponds are usually designed to have a total retention time of approximately 10 -20 days.
( ) ( ) 2019.16.2 −= TTdK
AAMH
BTP – Pond Treatment
Additional design guidelines for MP:
• The hydraulic retention times in all maturation ponds are equal,this gives the most effective removal at a certain total hydraulic retention time (Marais, 1974).
• The minimum hydraulic retention time per pond to avoid short-circuiting is 3 days (Marais, 1974).
• The organic surface load to the first maturation pond should not exceed 75% of the organic surface load of the preceding facultative pond (Mara et al., 1992).
• The hydraulic retention time in a maturation pond should not exceed the hydraulic retention time in the preceding facultativepond (Mara et al., 1992).
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Activated Sludge Process
- aerobic- suspended-growth - Design equations
PST AT SST
RAS
SW
SW
Influent biomass + biomass production = effluent biomass + sludge wasted
AAMH
BTP – Activated Sludge Process
Substrate utilization rate
XSKS
Ydtds
su
...1 max
+=⎟
⎠⎞
⎜⎝⎛ µ
( ) Xqdtds
u.= ( )SFq =
SKSq
qS +
=.max
[‘q’ is not a constant] >>>>
[qmax → Maximum substrate utilization rate]
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Activated Sludge Process
Food to microorganism ratio (F/M) Represents the daily mass of food supplied to the microbial biomass, X, in the mixed liquor suspended solids, MLSS Units are Kg BOD5/Kg MLSS/day
AAMH
BTP – Activated Sludge Process
Mass balance of biomass productionAccumulation= Inflow – Outflow
Where,X = mixed-liquor suspended solids, mg/LQ = Secondary influent flowrate, m3/sQR = return sludge flowrate, m3/sXR = Return activated sludge suspended solids, mg/LQw = Waste activated sludge flowrate, m3/sQe = Effluent flowrate, m3/sXe = Effluent suspended solids, mg/L
( ) eeRWRRR XQXQXQQQX −−−+=0
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Activated Sludge Process
(a) Definition Sketch for suspended solids mass balances for return sludge control: Secondary Clarifier mass balance
Aeration Tank
Q Q +QR
XSecondary Clarifier
Qe
Xe
Qw
QR
XR XR
System boundary
AAMH
BTP – Activated Sludge ProcessAssuming Xe is negligible and that QwXR is related to the
SRT, solving
Recycling Ratio (QR/Q = R) is then
The required RAS pumping rate can also be estimated by performing a mass balance around the aeration tank.
( ) Rwew XQXQQVXSRT
+−=
[ ]XXSRTXVXQQ
RR −
−=
/
( )( ) 1/
/1−
−=
XXSRTR
R
τ
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Activated Sludge Process
(b) Definition Sketch for suspended solids mass balances for return sludge control: Aeration
Tank Mass Balance
Aeration Tank
Q Q +QR
XSecondary Clarifier
Qe
Xe
QwXR
QR
XR
System boundary
AAMH
BTP – Activated Sludge Process
New cell growth can be considered negligible. If the influent Solids are negligible compared to the MLSS, the mass balance around the aeration tank results:
Accumulation= Inflow – Outflow ( )RRR QQXXQ +−=0
XXXR
R
R
−==
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP – Activated Sludge Process
Sludge Retention Time (SRT): To maintain a given SRT, the excess activated sludge produced each day must be wasted.
V = Volume of the reactor, m3
X = Aeration tank mass concentration, mg/LQw = Waste sludge flowrate from return sludge line, m3/dayXR = Concentration of sludge in the return sludge line, mg/LQe = Effluent flowrate from secondary clarifier, m3/dayXe = Effluent TSS concentration, mg/L
If it is assumed that the concentration of solids in the effluent from the settling tank is low, then
( )eeRw XQXQVXSRT+
=
Rw XQVXSRT =
( )SRTXVXQR
w =
AAMH
BTP – Activated Sludge ProcessTo determine the waste flowrate, the solids
concentration in both the aeration tank and the return line must measured. If wasting is done from aeration tank and the solids in the settled efflent are again neglected, then the rate of pumping can estimated by using the following relationships:
Where, Qw = Waste sludge flowrate from the aeration tank, m3/day
Thus, the process may be controlled by daily wasting of a quantity of flow equal to the volume of the aeration tank divided by the SRT
wQVSRT =
SRTVQw =
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment Process• Biofilm is an aggregate of microorganisms in which cells adhere
to each other and/or to a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS).
• Biofilm EPS, which is also referred to as slime (although not everything described as slime is a biofilm), is a polymeric conglomeration generally composed of extracellular DNA, proteins, and polysaccharides in various configurations. Biofilmsmay form on living or non-living surfaces, and represent a prevalent mode of microbial life in natural, industrial and hospital settings.
• The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium.
AAMH
BTP: Bio-Film Treatment Process
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment Process
Constraints and Opportunities In natural environments. Microbes can
negatively impact environments on a global level including producing and consuming atmospheric gases that affect climate; mobilizing toxic elements such as mercury, arsenic and selenium; and producing toxic algal blooms and creating oxygen depletion zones in lakes, rivers and coastal environments (Eutrophication). Furthermore, the incidence of microbial diseases such as plague, cholera, Lyme disease, and West Nile Virus are linked to global change.
AAMH
BTP: Bio-Film Treatment Process
In industrial environments. Biofouling, biocorrosion, equipment damage and product contamination are constant and expensive problems in industry. Biofilm contamination and fouling occur in nearly every industrial water-based process, including water treatment and distribution, pulp and paper manufacturing and the operation of cooling towers.
In human health. The human body is heavily colonized by microbes that have found it a great place to live. chronic, low-grade infections are related to the biofilm mode of growth.
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment ProcessBiofilms also offer huge potential for bio-remediating hazardous waste sites, bio-filtering municipal and industrial water and wastewater, and forming biobarriers to protect soil and groundwater from contamination.
The role of microbes in biofuels production e.g., methane, ethanol, hydrogen
The role of microbes in cleaning up pollutants (bioremediation)Biological treatment of pollution or reduction of pollution from current processes
AAMH
BTP: Bio-Film Treatment Process
Bioremediation of existed polluted areaCleanup of Superfund sites, oil spills
Environmental Monitoring: Indicator, Ames test, Microtox, Biosensors, ELISA (Enzyme-linked immunosorbent assay)
Prevention of pollution: (clean technology, Green technology) microbial removal of S compounds from coal, fungal pretreatment of logs before pulp and paper production, biodegradable plastic, biofuels
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment Process
AAMH
BTP: Bio-Film Treatment Process
A layer of microbes attached and proliferated on the surface of an object.
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment Process
1) Free-floating, or planktonic, bacteria encounter a submerged surface and within minutes can become attached. They begin to produce slimy extracellular polymeric substances (EPS) and to colonize the surface.
2) EPS production allows the emerging biofilm community to develop a complex, three-dimensional structure that is influenced by a variety of environmental factors. Biofilm communities can develop within hours.
3) Biofilms can propagate through detachment of small or large clumps of cells, or by a type of "seeding dispersal" that releases individual cells. Either type of detachment allows bacteria to attach to a surface or to a biofilm downstream of the original community.
AAMH
BTP: Bio-Film Treatment Process
1) Initial attachment, 2) Irreversible attachment,3) Maturation I, 4) maturation II, 5) dispersion
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment Process1) Free-floating, or planktonic, bacteria encounter a
submerged surface and within minutes can become attached. They begin to produce slimy extracellular polymeric substances (EPS) and to colonize the surface.
2) EPS production allows the emerging biofilmcommunity to develop a complex, three-dimensional structure that is influenced by a variety of environmental factors. Biofilm communities can develop within hours.
3) Biofilms can propagate through detachment of small or large clumps of cells, or by a type of "seeding dispersal" that releases individual cells. Either type of detachment allows bacteria to attach to a surface or to a biofilm downstream of the original community.
AAMH
BTP: Bio-Film Treatment Process
Bio-film Growth Process
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment Process
BiodegradationThe natural process in which microorganisms (bacteria, fungi) are able to completely or partially break down organic compounds to CO2 + H2O or other simple organic molecules that are inert or are readily metabolized by other organisms.
Mineralization
The degradation process is carried to the extreme, in which organic compounds are biodegraded to inorganic compounds.
AAMH
BTP: Bio-Film Treatment Process
Advantages of biofilm processes:
- higher process productivity (loading rates)
- higher biomass holdup- higher mean cell residence time- no need for biomass recirculation- creates suitable environment for each type of bacteria
- sustains toxic loads
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment ProcessTypes of biofilms: aerobic, anaerobic, anoxic
Process of biofilm formation
- formation of diffuse electrical double layer due to electrostatic forces and thermal motion
- transfer of microorganism to surface
- microbial adhesion
- biofilm formation
AAMH
BTP: Bio-Film Treatment Process
Bio-film Operation
X
Y
BiofilmLiquidFilm
Bulk Liquid
Supp
ort M
ater
ial
(a) Physical concept
Fully Penetrated
Partially Penetrated
SS
Sb
Subs
trate
Con
cent
ratio
n
X
Y
(b) Substrate concentration profile
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
BTP: Bio-Film Treatment ProcessBio-film Operation•Diffusion resistance•Inadequate supply of nutrients to inner portions of Biofilm•Limitations on product out diffusion•Attrition of reaction conditions
As biofilm thickness increases effectiveness factor (η) decreases
average rate of substrate consumptionEffectiveness factor η = ----------------------------------------------
substrate consumption at biofilm surface
AAMH
Research: Bio-Film
Landfill Leachate Treatment by Swim-bed Biofringe Technology
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Design for Secondary Sedimentation TankThis tank is placed after the biological sedimentation tankThe purpose is to remove the sludge from the biological plant due to the synthesis and microorganism oxidation processTherefore it should be properly designed in order to ensure the discharge of effluent is according the appropriate standardAlso known as humus tankOnly the circular tank is designed specializing for this type of sedimentation tank.
Design of Secondary Sedimentation Tank
AAMH
It is very important for treatment unit such as activated sludge plant and aerated lagoonWithout this tank, sludge could be settled. Therefore, final effluent will contain high suspended solid.Design for this tank similar is to the primary tank with a few differences due to the consideration of mixed liquor suspended solid (MLSS) in the secondary tank.Surface Overflow Rate (SOR) also has to be taken into account, it means that how much solid load should be settled for certain area of the plant
Design of Secondary Sedimentation Tank
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Design of Secondary Sedimentation Tank
QpuncakFlow rate
< 150Organic load at Qpeak (kg/m2.day)
3Minimum depth of tank (m)
150 – 180Flow rate of weir loading at Qpeak(m3/m.day)
< 30Surface loading rate at Qpeak (m3/m2. day)
2Minimum detention time at Qpeak (hour)
Value of PE < 5000Parameters
Design parameters for secondary sedimentation tank
133,
AAMH
Design Parameter for Secondary clarifierDesign of Secondary Sedimentation Tank
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
The area of activated sludge tank is determined by:
Where:A = area of sedimentation tank (m2) Q = inlet flow rate to the tank (m3/day) QR = return flow rate of sludge (m3/day) xa = concentration of MLSS (suspended
solid in the biological tank, mg/L) Gminimum = optimum sedimentation (kg/m2.day) because
of two factors:i) Gravitational force in the sedimentation tankii) Force from the pump to return the sludge from sedimentation tank to the aeration tank.
Design of Secondary Sedimentation Tank
A = (Q + QR) xaGminimum
Eq 9
AAMH
Activated sludge process
Figure show how return sludge occur Design parameters are given in Table [Slide 130]
Design of Secondary Sedimentation Tank
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
• It can be seen that, some of the sludge should be returned to the aeration tank (biological tank).
• Purpose: To maintain MLSS in the aeration tank
• In the activated sludge process, MLSS value is important to maintain at certain point in order to ensure good biodegradations process.
• If all the sludge are removed, SS are decreasing.
Design of Secondary Sedimentation Tank
AAMH
Rotary Biological Contactor (RBC)Rotary Biological Contactor (RBC)
inflow outlet
primary sludge
sludge return
primarysedimentation clarifier
Gujer2000
An aerobic, attached-growth wastewater treatment processes
Dr. Abu Ahmed Mokammel Haque ([email protected])
October 3, 2010
School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, P. Pinang, Malaysia
AAMH
Rotary Biological Contactor (RBC)Rotary Biological Contactor (RBC)
outlet
primary sludge
sludge return
primarysedimentation clarifier
Gujer2000
AAMH
Appropriate Treatment Steps
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