1. Biodegradation Process

2. Biodegradation – 6 x 106 chemicals synthesized
1000 new chemicals / year
60,000 to 95,000 commercial use
Chemicals in the world
Microbes used to treat synthetic contaminants
Biodegradation used to treat sewage, solid waste, industrial residues & man made xenobiotics
Biodegradation –
Decomposition or destruction of contaminant molecule by the action of enzymes
Microbes mineralize Organic contaminants to CO2 & carbon + energy & release inorganic forms of N, P, S
Molecule enter inside the cell  Biotransformation and bio-conversion  less toxic form

3. Agents for Biodegradation
Due to their catabolic versatility (good for all aspects), species composition, fast reaction
Agents for Biodegradation
Microbes (bacteria, algae, fungi)
Biochemical reactions of microbes
By step wise reaction
Degrade macromolecule into smaller units

4. Bioagumentation: addition of microbes
Macromolecules 고분자
Carbohydrates
탄수화물
Lipids
Proteins
Nucleic acids
To increase Bioremediation process
Bioagumentation: addition of microbes
Microbial enzyme act as catalysts
Conjugation: Transfer of metabolic capacities to indigenous bacteria to increase degradative microbes
Breakdown of
Complex organic substances by heterotrophs
Oxidation of inorganic compounds by autotrophs
Photosynthetic reaction of phototrophs
Energy generated

5. Enzymes for Biodegradation Common Enzymes produced by Microbes
Extracellular or intracellular
Speed up reaction without alteration
Extracellular breakdown large complex molecules & enable entry into cell
Common Enzymes produced by Microbes
Mono- & dioxygenases & dehydrogenases

6. Optimal conditions for Biodegradation
This is lag period so microbes adjust the present of organic compounds
Presence of microbes to decompose contaminants
Pollutant induce the microbes to produce enzymes
Number of microbes act one after other
Each performing special function
Microbes – contaminant contact makes biodegradation

7. Depends on the nature of toxic compound
Detoxification or partial detoxification occur by several processes
Depends on the nature of toxic compound
After lag phase
Favourable environmental factors to speedup biodegradation
Water, pH & temperature

8. More hazard due to movement in biological system Lipophilic compounds
Nature of Biodegradation Reactions
Oxidation, Reduction, Hydrolysis & structural rearrangements
Simple organic compounds (Carbohydrates, proteins, fats & nucleic acids)
Molecules with branched chain
(simple or fused aromatic ring, cyclo-paraffins)
Quickly degrade
Difficult to degrade
Step wise removal of substituted atoms
More hazard due to movement in biological system
Lipophilic compounds

9. Dynamism of Biodegradation Reaction Rate of biodegradation depends on
Capacity to adjust microbes activity based on contaminant concentration
Process of biodegradation
Ratio between “concentration required to saturated the system : contaminant concentration within a biological system”
Rate of biodegradation depends on
Below saturation
Larger load of decomposition
Reduced the concentration in system (diminishes)
Constant decomposition per unit time
Decompose faster
Slow down decomposition
Low pollutant concentration in soil
High pollutant concentration in soil

10. High concentration of pollutant Low pollutant concentration
When pollutant retention (half of original value) within a biological system
“Half-life”
High concentration of pollutant
Low pollutant concentration

11. Directly proportional Contaminant entry 4 g/12 hr
Small quantities of contaminants
Microbes remove effectively
Before 100% decomposition
Concentration in media (Vs) degradation or elimination by microbes
Accumulate in Microbial cells
Entry of fresh dose of contaminants
Microbes adjust Equilibrium between intake & rate of decomposition
Directly proportional
직접 비례하는
Contaminant entry 4 g/12 hr

12. Finally Reach Steady State
Contaminant half life time is 12 hrs (10 ppm reduced to 5 ppm after 12 hrs later by microbial degradation) or (100 ppm reduced to 50 ppm after 12 hrs later by microbial degradation)
Time 0
Time 12 hr
Time 24 hr
Time 36 hr
Time 48 hr
Contaminant addition
4 g
4 g
4 g
4 g
4 g +
2 g + + +
6 g
3 g
7 g
3.5 g
Microbial degradation
7.5 g
3.75 g
4 g
2 g
1 g
0.5 g
After degradation conc raised by
0.25 g
0.125 g
& so on..
Finally Reach Steady State

13. State of contaminant with different half-lives
Half life & rate of uptake important for biodegradation Long half life pollutant  more amount accumulate in environment if rate of input is same

14. State of contaminant with different half-lives Contd…
Natural environment  received small exposure & spread long duration
Constant degradation affect simple arithmetic addition of contaminants
As time increase  contaminant reach lethal level but microbes adjust to this
Reach above adjustable level  mechanisms fail
Rate of contaminant on biodegrading organisms
Microbial biodegradation trying maintain the contaminant at safe level
Bioremediation (self purification) is possible below self purification level
Increase the contaminant level (beyond critical level)  self purification lost & enfeeble (weak) decomposition