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Wastewater Treatment

CivilEngineeringDepartment

Faculty

of

Engineering

and

Technology

TheUniversityofJordan

Instructor: Ghada Kassab, PhD

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Secondary Treatment

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Biological wastewater treatment

Objectives:

transform (oxidize) biodegradable particulate or dissolved

constituents into acceptable end products

Capture and incorporate suspended and non settlealble solids into

a biological floc or biofilm.

Transform or remove nutrients

Role of microorganisms

Removal of dissolved and particulate CBOD and the stabilization

of organic matter, accomplished by variety of microorganisms

principally bacteria.

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Bacteria

Under controlled condit ions, bacteria is used to stabilize organic

matter

Bacteria is classified as a plant because of their structure method of food intake.They are single cell organisms that utilize soluble food.

Categories

Sphere

RodSpiral

Size

Common bacteria are from 0.3-3 micron

Rod 0.5-1.0 wide, 1.5-3.0 longSphere 0.5-1.0 micron

Spiral 0.5-5.0 micron wide, 6-15 micron long

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Bacteria

Chemical composition

80% water

20% dry matter

Dry matter

90% organic

10% inorganic

Organic fraction

50% carbon

22% oxygen

12% nitrogen

9% hydrogen2% phosphorous

Inorganic fraction1% Sulfur

1% Potassium

1% Sodium

0.5% Calcium

0.5%Magnesium0.5% Chlorine

0.2% Iron

0.3% Other trace elements

C5H7O2N

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Types of Biological Processes

Two main categories

1. Suspended growth processes

Microorganisms responsible for treatment are maintained in liquid suspension by

appropriate mixing methods

Many suspended growth processes are operated with positive dissolved oxygen

concentration (aerobic).

Most common suspended growth system is theActivated Sludge system

2. Attached growth processes

The microorganisms responsible for the conversion of organic material or nutrients

are attached to an inert packing material. Organic material and nutrients are

removed from wastewater flowing past the attached growth (biofilm) Packing material include rock, gravel san and wide range of plastics

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Microbial metabolism

To reproduce and function properly, an organism needs:

Source of energy and carbon for synthesis of new cellular material

Inorganic elements (nutrients):

Macro nutrients: nitrogen, Phosphorous and potassium (NPK)

Micro nutrient: sulfur, calcium, magnesium, Zn, Mn, Co, Cu, Ni.

Organic nutrients : amino acids, nitrogen based organics andvitamins

(Energy source + carbon source) referred to as substrate

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Carbon source

Carbonforcellgrowth

)(formation

of

new

cells

Organic

matter Carbon

dioxide

Called Heterotrophs

Organism that use organic

matter for formation of new

cell

Drive cell carbon for CO2

Called Autotrophs

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Energy source

Energysource

LightCalled

phototrophs

heterotrophsAutotrophs

(algae)

Chemical

oxidation

Called

chemotrophs

heterotrophs Autotrophs

Obtain energy from

oxidation of organic

compounds

(bacteria, fungi, algae)

Obtain energy fromoxidation of inorganic

compounds; ammonia

and nitrate

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ChemotrophsEnergy producing reactions are an oxidation-reduction reaction (involves thetransfer of electron from an electron donor (undergoing oxidation) to electron

acceptor (undergoing reduction).

Electron donor can be organics or inorganic depending on microorganismElectron acceptor can also be organics or inorganic depending on

microorganisms.

When oxygen used as electron acceptor, the reaction is aerobic.

When other electron acceptor is used, the reaction is anaerobic.

Organism that can only meet their energy need with oxygen are called

obligate aerobic microorganism.

Some bacteria can use oxygen or other electron acceptor when oxygen is not

available are called facultative.

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Aerobic, hetertrophs

Synthesis

Bacteria

Energy

Organic

compound

New cells

CO2

and H2O

O2

NH4

Synthesis

Bacteria

Energy

CO2 New cells

NO3-, NO2

-

O2Aerobic, autotrops

nutrients

nutrients

Electrondonor

Electron

acceptor

Electron

acceptor

Electron

donor

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Synthesis

Bacteria

Energy

Organic

compound

New cells

CH4 and CO2

nutrients