Principles and recent trends in biologicalwastewater treatment technology
Team E-Kansai
GEC Technical Coordinator
Chuzo Nishizaki

Outline of This Presentation
1. Basics of Microbiology
2. Biological Wastewater Treatment
2-1. Aerobic Treatment
2-2. Anaerobic Treatment
2-3. Facultative Treatment
2-4. Nitrogen and Phosphorus Removal
3. Recent Trends
4. Conclusion

1. Basics of Microbiology-Organisms related to waste water treatmentprokaryotic organism

eukaryotic organism

Bacteria(Major player)

actinomycete

fungi
yeastmushroom

blue-green algaealgae
Archaea(Major player)

protozoa

is very related to the waste water treatment

plant

is not much related to the waste water
treatment

animal

1. Basics of Microbiology-Structure of Bacterial Cells(Artifact)

Resource : Murray PR, et al. “Medical Microbiology”

1. Basics of Microbiology-Bacterial Growth ConditionsEnvironmental
Factors

OutlineWater

・The growth of bacteria is dependent on the existence of water.

pH・Most microorganisms grow best when the pH is around 7.
Nitrosomonas: 7.5～8.0 (optimum pH range)
Nitrobacter: 7.3～7.5 (optimum pH range)
Thiobacillus and Fungi : 5 (best growing)

Temperature(maximum growth)

Nutrients

qT=q20(1.07)T-20 T : Temperature(℃)
Mesophilic bacteria : 20oC - 42oC
qT : Rate of substrate utilization
Thermophilic bacteria : 40oC - 70oC
Extreme thermophilic bacteria : 70oC-100oC

Macronutrients : C, O, H, N, S, P, K, Ca, Mg and Fe
Micronutrients : Mn, Mo, Zn, Co, Cu, Ni, V, B, Cl, Na, Se, Si and W

Dissolved Oxygen

Obligate aerobic bacteria: Pseudomonas sp. etc.
Obligate anaerobic bacteria : Clostridium perfringens etc.
Facultative anaerobic bacteria : E.coli, Citrobacter, etc.

Light・The growth of photoautotrophic bacteria is dependent of light.

1. Basics of Microbiology-Metabolism of Heterotrophic BacteriaO2
Catabolism

CO2

Respiration
Carbon ingestion
Maintenance

fe0

Flagella rotation
Active transport etc.

Anabolism

Energyfs0

HeatGrowth
New biomass

Note : fe0+fs0=1
Source : Strathkelvin Instruments Ltd.

1. Basics of Microbiology-Glycolytic Pathway and Cell Respiration (Catabolism)-Fermentation

Aerobic Respiration

Source : David Sadava, H. Craig Heller et al. : Life :T he Science of Biology 8th Edition

1. Basics of Microbiology-Fixation of Carbon Dioxide (Anabolism)Plants and blue-green algae,
photosynthetic bacteria is aphotoautotrophic organism.
Chemoautotrophic bacteria
use CO2 as a carbon source
like a photosyntheticorganism and grow. Calvin
Benson cycle is what isknown as a major cycle toassimilate the CO2 as acarbon source in these
autotrophic organisms.
Note : RuBisCO→Ribulose 1,5-bisphosphate carboxylase/oxygenase
Resource : Candela Open Courses

1. Basics of Microbiology-Typical fs0 and μ*) Values for Key Bacterial TypesOrganism TypeElectronDonor

ElectronAcceptors

CarbonSourcefs0(-)μ(d-1)

Aerobic , Heterotrophs

BOD

O2

BOD

0.6

8.4

Denitrifiers

BOD

NO3-BOD

0.5

4

Nitrifying Autotrophs

NH4+NO2-O2
O2

CO2
CO2

0.14
0.10

0.92
0.62

Methanogens

acetateH2acetate
CO2acetate
CO20.05
0.08

0.3
0.5

Sulfide Oxidizing Autotrophs

H2SO2

CO20.2

1.4

Sulfate Reducers

H2acetate

SO42SO42-

CO2acetate

0.05
0.08

0.29
0.5

Fermenterssugarssugarssugars

0.181.2μ*) ：maximum specific growth rate
Source : Bruce E. Rittmann, Perry L. McCarty : Environmental Biotechnology: Principles and Applications

2. Biological Wastewater Treatment-Aerobic TreatmentOxygen
DemandReactor Types

Popular Names

Effective Microorganisms① Conventional activatedsludge process (CAS)
Suspendedgrowth② Oxidation ditch (OD)
③ Membrane bioreactors(MBR)

Aerobic

Fluidized-bed④ Carrier-added activatedsludge process⑤ Trickling filter process

Packed-bed⑥ Contact oxidation process⑦ Rotating biologicalcontactor (RBC)

Activated sludge-related
bacteria
Pseudomonas
Flavobacterium
Corynebacterium
Aeromonas
Zoogloea
Acinetobacter, …

2. Biological Wastewater Treatment-Anaerobic & Facultative TreatmentOxygen
DemandHabitation

Popular Names

Suspended
growth⑧ Completely mixed

Fixed-bed⑩ Up-flow packed beds

Anaerobic
Fluidized bed⑨ Anaerobic contact⑪ Fluidized andexpanded beds (AFBR)⑫ Up-flow Anaerobic
Sludge Blanket (UASB)

FacultativeStabilization
pond⑬ Facultative type

Effective Microorganisms

Acidogenesis
Clostridium
Bacillus, …
Methanogenesis
Methanobacterium
Methanosarcina, …

PhotoautotrophsChlorobium, Algae, etc.
Heterotrophs
Pseudomonas, etc.

2. Biological Wastewater Treatment-Advanced TreatmentRemoval Object

Popular Name
⑭ Wuhrmann process

Biological Nitrogen
Removal

Biological Phosphorus
Removal
Biological Nitrogenand Phosphorous
Removal⑮ Nitrification liquid
circulation process

Effective Microorganisms
Ammonia-oxidizing bacteria
Nitrosomonas
Nitrite-oxidizing bacteria
Nitrobacter
Denitrifying bacteria
Pseudomonas, Microccus,Paracoccus,Alcaligenes,etc.

＊） Anammox process

Ammonia-oxidizing bacteria
Anammox bacteria*)⑯ Anaerobic- aerobic
ASP

Dephosphorization bacteria*)⑰ Anaerobic-anoxicASP

Ammonia-oxidizing bacteria
Nitrite-oxidizing bacteria
Denitrifying bacteria
Dephosphorization bacteria*)

Note*) : Ecology has not been fully elucidated

2-1. Aerobic Treatment① Conventional Activated Sludge Process(CASP)

Aeration Tank

Return Sludge

Effluent

2-1. Aerobic Treatment① Food Chain in Activated Sludge( ) : population in activated sludge2-1. Aerobic Treatment① The greatest feature of CASP

• CASP greatest feature is that the bacteria(activated sludge) grown by blowing air intosewage in the aeration tank is transported to thesedimentation tank, and then separated into solidand liquid, and again returned to the aerationtank.
• Accordingly, it is possible to manage separately
the time required for the bacteria growth(generation time) and hydraulic residence time in
the aeration tank (water treatment time).

2-1. Aerobic Treatment① Advantages and Disadvantages of CASP・High reduction of BOD and pathogens (up to 99%) at after
secondary treatment

Advantages

・Can be operated at a range of organic and hydraulic loading
rates
・High effluent quality
・Little land required compared to extensive natural system(e.g. Stabilization ponds)
・High energy consumption, a constant source of electricity isrequired.
・High capital and operating costs

Disadvantages

・Requires operation and maintenance by skilled personnel
・Prone to complicated chemical and microbiological problems
・Sludge require further treatment and appropriate discharge

Resource : Sustainable Sanitation and Water Management (SSWM)

2-1. Aerobic Treatment① Typical Process Operating Factors (ASP)F/M

BOD Removal
Efficiency

Process
Modification（kg BOD5/㎥・d）（mg/l）（kg BOD5/kgMLVSS・d）

Conventional0.6

1,000~3,000

0.2~0.5

ContactStabilization

1.0A

Modified
Aeration

1.5~6300~600

0.5~3.5

60~85B

0.8~4

Extended
Aeration

0.3

3000~5000

0.05~0.2

85~95B>14

Volumetric

MLSS

0.2~0.5（％）

9590

SRT（d）

4~104~15

A : Contact Tank→1,000~3,000mg/l ; Stabilization Tank→5,000~10,000mg/l
B : Higher efficiency is based upon soluble effluent BOD5.
Source : Bruce E. Rittmann, Perry L. McCarty : Environmental Biotechnology: Principles and Applications

2-1. Aerobic Treatment② Oxidation Ditch (OD)

Characteristic of Oxidation Ditch Process

1. Operation management is easy.
2. Even if there is an hourly fluctuation of inflow load and a decrease of watertemperature, this process can complete stable organic removal.
3. The amount of excess sludge generated of this treatment method is less thanthat of the conventional activated sludge process.

2-1. Aerobic Treatment③ Membrane Bioreactors（MBR）
MBR can be classified into 3
types according to the location
for installing the membrane
module in convenience.
1. Immersion type (integrated)
2. Immersion type (another tankinstallation)
3. Outside tank type

Characteristic of Membrane Bioreactors

1. Process function is not affected by the change of the sludge settlingproperties.
2. Since we can keep the MLSS concentration high in the reaction tank , itis possible to make the facility compact.
3. Treated water is clarified, it is also possible to apply directly to recycling.
Resource : Guidelines for membrane treatment technology introduction into the sewer [1st edition],May 2009

2-1. Aerobic Treatment④ Carrier-added Activated Sludge Process

Characteristic of Carrier-added Activated Sludge Process

1. This method can retain microorganisms at a high density, such as nitrifying
bacteria in a carrier that is flowing together with the activated sludge.
2. Therefore, by adopting this method, it is possible to compact the reactiontank.
3. This process needs a special solid – liquid separation tool in the bioreactor.

2-1. Aerobic Treatment⑤ Trickling Filter Process

Resource : http://www.db.pwri.go.jp/pdf/D8113.pdf

Advantage・Low construction and maintenance costs compared with CAS・Easy maintenance without the return of the sludge
・The outbreak of filter fly or odorDisadvantage

・Poor transparency of the treated water・Large head loss

2-1. Aerobic Treatment⑥ Contact Oxidation ProcessMediaAdvantage

・Easy maintenance without the sludge returning
・Less generation of waste sludge

・Attention should be paid to sludge deposition ofDisadvantage contact oxidation tank.
・Poor transparency of the treated water
Source : KAJIMA AQUATECH CO., LTD.

2-1. Aerobic Treatment⑦ Rotating Biological Contactors

Source : http://www.unido.or.jp/en/technology_db/1677/

・Low Operating Cost
Advantage・Low Sludge Generation
・Easy maintenance without the return of the sludge
・Poor transparency of the treated water

Disadvantage

・It is required discharge device as the peeled biofilm does notaccumulate in the contact tank.

2-2. Anaerobic Treatment-Configuration of Typical Anaerobic Reactor-

2-2. Anaerobic Treatment-Typical Operating FactorsType

Operating Factors⑧ Completely Mixed

・DT=15-25 d at 35℃, Organic loading=1-4 kg-CODCr/㎥/d・This has been used for treatment of municipal sludge.

⑨ Anaerobic ContactProcess

・HRT=0.5 d, Organic loading=2-2.5 kg-BOD/㎥/d・To prevent sludge floating in the sedimentation tank,the system is often provided a degassing device.

⑩ Upflow and Downflow
Packed beds

Measures to prevent the bed-clogging：・The SS component of the influent water should beremoved in advance.
・Periodically carrying out the backwashing⑪ Fluidized andExpanded Beds (AFBR)

・Organic loading=100 kg-CODCr/㎥/d・This combines a suspended-growth system and an
attached-growth system.

⑫ Upflow Anaerobic
Sludge Blanket (UASB)

・Production and maintenance of the granule is the key tothe success of this process.

Source : Bruce E. Rittmann, and Perry L. McCarty : ”Environmental Biotechnology : Principles and Applications”

2-2. Anaerobic Treatment
Advantages and Disadvantages of Anaerobic Treatment
・Low production of waste biological solids
・Low nutrient requirements
Advantages

・Methane is a useful end product・Generally, a net energy producer
・High organic loading is possible
・Low growth rate of microorganisms

Disadvantages

・Odor production
・High buffer requirement of pH control
・Poor removal efficiency with dilute wastes

Source : Bruce E. Rittmann, and Perry L. McCarty : ”Environmental Biotechnology : Principles and Applications”

2-3. Facultative Treatment⑬ Facultative Stabilization Pond

Source : Bruce E. Rittmann, Perry L. McCarty : Environmental Biotechnology: Principles and Applications

2-3. Facultative Treatment⑬ Typical Operating Factors of Stabilization Pond
Type

Operating Factors

Anaerobic
PrimaryTreatment

BOD loading : 100g-BOD/㎥/d（below 10℃）→BOD removal : 40%
BOD loading : 300g-BOD/㎥/d（above 20℃）→BOD removal : 60%
Retention time : 1 day (minimum)

Facultative
SecondaryTreatment

Depth : 1～2m
Surface BOD loading : 350 (1.107 - 0.002T)T-25-kg-BOD/ha/d→BOD removal : ca.90%
Retention time = 2 AfD / (2 Qi - 0.001 e Af) day(Minimum 5day below 20℃; 4day above 20℃)
Af: Facultative pond area (㎡); QI: Influent flow (㎥/d)e: Net evaporation rate (mm/d)； D: Pond depth(m)AerobicMaturation

Additional maturation pond(s) may be sometime used (depends onthe effluent quality requirements) succeeding the facultative pond.

Resource : Hamzeh Ramadan and Victor M. Ponce : ”Design and Performance of Waste Stabilization Ponds”

2-3. Facultative Treatment⑬ Advantages and Disadvantages of Stabilization Pond
Require little energy, with systems designed to operatewith gravity flow.
Easy to operate.

Advantages

・Moderately effective in removing settleable solids, BOD,
pathogens, fecal coliform, and ammonia.
・The quantity of removed material will be relatively small
compared to other secondary treatment processes.
・Requires relatively large areas of land.

Disadvantages

・Settled sludge and inert material require periodic removal.
・Strong odors occur when the aerobic blanket disappears.
・Burrowing animals may be a problem.

Resource : EPA ”Wastewater Technology Fact Sheet-Facultative lagoons”

2-4. Nitrogen and Phosphorus Removal-Denitrification Process-2-4. Nitrogen and Phosphorus Removal-Dephosphorization Process-2-4. Nitrogen and Phosphorus Removal-Characteristics of Typical Treatment ProcessType

Characteristics⑭ Wuhrmann process(Post-anoxic )・Denitrification rate is proportional to the endogenous
respiration rate in the mixed liquor.
・Long detention time required in the post anoxic tank.

⑮ Nitrification liquid
circulation Process(Pre-anoxic)

・Internal recycle is provided to feed more NO3-to theanoxic zone directly from aerobic zone.
・Denitrification rate and overall nitrogen removal rateincrease.

⑯ Anaerobic-aerobic
activated sludge process

・The process enhances phosphorus removal while
reducing sludge-bulking organisms.
・Physical layouts and flow schemes are similar toconventional activated- sludge plants.

⑰ Anaerobic-anoxic-aerobic
activated sludge process

・This process combines ⑮ and ⑯ processes.

＊）Anammox process

・In anaerobic conditions, NH4+ and NO2- is converted
into a small amount of nitrate ions and nitrogen gas.

3. Recent Trends-Biological Wastewater Treatment Technologies⑮Nitrification-Denitrification Process⑯Dephosphorization Process

Nitrogen andPhosphorous Removal

Energy Saving⑫Anaerobic Treatment Process⑬Stabilization Pond

①Conventional
Activated Sludge
Process⑥Contact Oxidation Process⑫Anaerobic Treatment Process

Space Saving

Sludge Reduction③Membrane Bioreactor④Immobilized Carrier Added Process

4. Conclusion• Basic knowledge of biology is by all means necessary
for mastering the biological wastewater treatment
technology.
• On the other hand, the waste water treatment
technology that meets the needs of the site（Energysaving, Sludge reduction etc.） is required from the site.
• In order to respond to it, we should firstly find out auseful function from the possibility of the infinite withthe microorganisms. Then, we need to utilize its
function in the process of wastewater treatment tomeet the needs of the site.

Thank you for kind attention!