Bioremediation uses microorganisms to degrade contaminants in soil or water. It can be used to treat soils contaminated with organic compounds like petroleum hydrocarbons. The microorganisms break down the contaminants into non-toxic byproducts through oxidation-reduction reactions, transferring electrons to terminal electron acceptors. Factors like pH, temperature, oxygen, nutrients, and toxicity levels must support microbial growth for bioremediation to succeed. It has advantages of being lower cost than mechanical methods and allowing in-situ treatment, but also risks partial degradation and sensitivity to environmental conditions.

1. BIOREMEDIATION
Presented by
KARTHIKA MOHANAN

2.  Bioremediation is a process in which microorganisms degrade
organic contaminants or immobile inorganic contaminants
 Also known - enhanced bioremediation or Engineered
bioremediation
 Bioremediation is commonly used for the treatment of soils
contaminated with organic compounds (petroleum hydro
carbons)
 -cannot degrade heavy metal but can change valance states
(hexavalent chromium to trivalent chromium)

3.  Based on microorganisum used:-
Aerobic, cometabolic, and anaerobic
 Based on location :-
In-situ bioremediation & ex-situ bioremediation
 Based on presents of microorganism:-
Indigenous microorganisms – Microorganisms are native to
site.
Exogenous microorganisms – Microorganisms are taken from
other locations, cultured in laboratory, then added to
contaminated soil

4. Requirements
 Condition for microorganisms to grow and survive
 pH - should be between 5.5-8.5
 Temperature - between 15-45oc
 Oxygen - >2mg/L aerobic reaction
- < 2mg/L anaerobic reaction
 Nutrients -carbon, hydrogen, oxygen, nitrogen, phosphorus
The actual quantity of these nutrients depends on
the BOD of contaminated soil.
 Toxicity - High conc. of contaminants can be toxic
Some contaminants even at low conc. may be toxic

5. Fundamental Process
Bioremediation processes may be directed toward
accomplishing:
1.Destruction of organic contaminants
2.Oxidation of organic chemicals thereby the organic
chemicals are broken down to smaller constituents
3.Dehalogenation of organic chemicals by cleaving chlorine
atoms or other halogens from a compound

6. Degradation is a complex oxidation - reduction reaction.
The electrons or reducing equivalents produced must be
transferred to a terminal electron acceptor (TEA)
Depending upon TEA, bacteria are grouped into three
categories:
 Aerobic bacteria – Only use molecular oxygen as a TEA
 Facultative Aerobes / Anaerobes – Which can utilize
oxygen or when oxygen is low or non-existent may
switch to nitrate, manganese oxides or iron oxides as TEA
 Anaerobes – They utilize sulfate or carbon dioxide

7. Advantages
Complete degradation of organic compounds to non-toxic by-
products
Minimum mechanical equipment requirements
Can be implemented as in-situ or ex-situ process
Cost is low

8. Disadvantages
 There is a potential for partial degradation to equally toxic,
more highly mobile by-products
 The process is highly sensitive to toxins and environmental
conditions
 Excessive monitoring required
 Difficult to control volatile organic compounds during an ex-
situ process
 A longer treatment time required

9. THANK YOU