The document discusses biodegradation and bioremediation. It defines biodegradation as nature's way of breaking down organic matter using microorganisms. Biodegradation can occur aerobically or anaerobically. Bioremediation uses microorganisms to transform hazardous contaminants into less harmful byproducts and is used to treat contaminated sites. There are two types of bioremediation - in situ, which treats contamination on site, and ex situ, which physically extracts contaminated media. Ex situ techniques include solid phase methods like landfarming and biopiling, and slurry phase treatment in bioreactors. Bioremediation has advantages of being relatively low cost and having general public acceptance.

1. Biodegradation & BioremediationBiodegradation & Bioremediation
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2. BiodegradationBiodegradation
Biodegradation is nature's way of recycling wastes or breaking down organic matter
into nutrients that can be used by other organisms. "Degradation" means decay and
“Bio" means that the decay is carried out by a huge assortment of bacteria, fungi,
insects, worms and other organisms that eat dead material and recycle it into new
forms.
The US EPA defines biodegradation as “A process by which microorganisms
transform or alter (through metabolic or enzymatic action) the structure of chemicals
introduced into the environment”.
Biodegradation is a process by which organic materials are changed through
chemical processes from complex molecules into simpler molecules.
Example: Banana peel being reduced from cellulose to H2O, CO2 and humus in a
compost pile.
Biodegradation is a waste management & recycling system that degrades everything
from yard waste to crude oil. This process helps to keep our planet clean and
healthy.

3. Where does biodegradation take place?
Biodegradation can take place with O2 (aerobically) or without O2
(anaerobically). Aerobic respiration is a process in which micro-
organisms such as bacteria and fungi convert carbon into energy and
produce CO2, H2O and humus (biomass) as waste products.
Aerobic respiration is a fast and efficient source of energy and an
effective means to biodegrade waste matter.
Anaerobic biodegradation, called anaerobic fermentation, is a
complex process by which microorganisms convert carbon into
energy and produce CO2, Methane and humus as waste products.

4. Composting is a good example of aerobic biodegradation, which is
widely used to divert municipal wastes such as yard trimmings from
landfills. Some cities have large industrial composters that are able
to accept food wastes and some paper and plastic items.
Anaerobic biodegradation is often used to treat municipal sewage, as
it is extremely efficient at reducing known pathogens in human and
animal waste. This process produces methane as a waste gas this is
captured and utilized for energy production.
Example

5. Type Of Biodegradation
There are basically two generalized categories of biodegradation.
Mineralization, also referred to as bio-mineralization. Mineralization
is the process by which microorganisms work on organic compounds
and by a chemical process, reduce them to inorganic material such as
H2O, CO2 and also possibly other such inorganic compounds.
Mineralization involves total degradation of the organic matter.

6. The second category is called biotransformation. Biotransformation
essentially differs from mineralization in that the organic matter is
not degraded totally. While a part of it is degraded, another part is
converted into other smaller chain organic compounds.
This raises two possibilities: The converted smaller chain organic
compounds may be either toxic or non toxic. In the case of the
pesticide Dichloro Diphenyl Trichloroethane (DDT), the
biotransformation yields an even more toxic compound. Another
example of biotransformation is the fermentation process, in which
sugar, a long chain organic compound, is transformed into ethanol.

7. Conventional Methods Of Remediation
Dig up and remove it to a landfill
Risk of excavation, handling and transport of hazardous material Very
expensive to find another land to finally dispose these materials
Cap and Contain
Maintain it in the same land but isolate it, Only an interim solution
Requires monitoring and maintenance of isolation barriers for a long
time.
Products are not converted into harmless products. Stay as a threat!
Is there a better approach?

8. Better Approaches
Better approaches are; To destroy them completely, if possible OR
Transform them in to harmless substances.
Methods already in use;
High temperature incineration, Chemical decomposition like dechlorination, UV
oxidation
But, are they effective?
Yes, But only upto some extent
Drawbacks
Technological complexity, expensive for small scale application, Lack of public
acceptance, especially in case incineration as more toxic compounds are generates,
materials may be released from imperfect incineration- Cause undesirable
imbalance in the atmosphere. Ex. Ozone depletion, Fall back on earth and pollute
some other environment, Dioxin production due to burning of plastics – leads to
cancer and may increase exposure to contaminants, for both workers and nearby
residents.

9. What is Bioremediation?
Using subsurface microorganisms to transform hazardous
contaminants into relatively harmless byproducts, such as ethene and
water.
Bioremediation is the intentional use of biological degradation
procedures to remove or reduce the concentration of environmental
pollutants from sites where they have been released.
The concentrations of pollutants are reduced to levels, acceptable to
site owners and/or regulatory agencies.

10. Types of Bioremediation
In Situ Bioremediation
Ex Situ Bioremediation

11. In-Situ Bioremediation
In situ bioremediation involves the treatment of the contamination on
site. In case of soil contamination, in-situ bioremediation involves
the addition of mineral nutrients.
These nutrients increase the degradation ability of the
microorganisms that are already present in the soil.
Sometimes new microorganisms are added to the contaminated area.
Microorganisms can sometimes be genetically engineered to degrade
specific contaminants. An example of a microorganism that has been
genetically engineered is Pseudomonas fluorescens HK44. These
genetically engineered microorganisms can be designed for the
conditions at the site.

12. Approaches
Which approach is taken, depends upon the relationship between
the type of contamination and the type(s) of microorganisms
already present at the contamination site.
For example; if the microorganisms already present are appropriate
to break down the type of contamination, we only need to "feed"
these microorganisms by the addition of fertilizers, nutrients,
oxygen, phosphorus, etc.

13. Methods for supplying O2
Two methods are used for supplying O2 to the microorganisms.
Bioventing: This consists of blowing air from the atmosphere into the
contaminated soil.
First, injection wells must be dug into the contaminated soil. How
many wells, how close together they go, how deep they are dug, all
depends on the factors affecting the rate of degradation (type of
contamination, type of soil, nutrient levels, concentration of
contaminants). Once all of the injection wells are dug, an air blower
is used to control the supply of air to the microorganisms.
These injection wells can also be used to add nitrogen and
phosphorus, maximizing the rate of degradation.

14. Hydrogen Peroxide (H2O2) Injection: In cases where the
contamination has already reached the groundwater,
bioventing will not be very successful so H2O2 injection is
used.
Its function is similar to bioventing, using the H2O2
instead of air blowers to deliver oxygen to the
microorganisms. If the soil is shallow (the groundwater is
fairly close to the surface) the H2O2 can be administered
through sprinkler systems.
If the groundwater is fairly deep beneath the surface,
injection wells are used.

15. Ex Situ Bioremediation
Ex situ bioremediation involves the physical extraction of the
contaminated media to another location for treatment. If the
contaminants are just in the soil, the contaminated soil is excavated
and transported for treatment. If the contamination has reached the
groundwater, it must be pumped and any contaminated soil must also
be removed.
There should ideally be no remaining contaminants, but usually
a minimal amount of contaminants is remaining in the contaminated
site. If minimal contaminants do remain in the soil, they can likely
be broken down by the naturally occurring microorganisms already
present at the site.

16. Types Of Ex-Situ Bioremediation
Two main types of ex-situ bioremediation.
Solid Phase: Solid phase treatment consists of placing the excavated
materials into an above ground enclosure. Inside this enclosure, the
contaminated soil is spread over a treatment bed. This treatment bed
usually has some kind of built-in aeration system. Using this system,
cleanup crews are able to control the nutrients, moisture, heat, oxygen
and pH. This allows them to maximize the efficiency of the
bioremediation.
The soil can also be tilled like farmland, helping to provide oxygen
and enable additional aerobic biodegradation of the contamination.
Solid phase treatment is especially effective if the contaminants are
fuel hydrocarbons. However, it require a lot of space and sometimes it
cannot be used for that very reason.

17. Types of solid phase
bioremediation techniques
There are three solid phase bioremediation techniques.
They are:
Landfarming
Biopiling
Composting.

18. Landfarming
Landfarming is the most simple of the three types of solid phase
bioremediation.
It involves the excavation and spreading of the contaminated soils onto
a lined bed (pad). The soil is usually spread so that it is about 18 inches
thick all around.
The bed typically has a collection system, to collect any leachate that
may seep through the contaminated soil.
Leachate is a solution containing contaminants that are picked up
through the leaching of soil.
Generally, a high molecular weight, heavily nitrated and chlorinated
compounds tend to slow down the rate of contaminant degradation

19. The soil is tilled and turned over repeatedly to allow aeration.
Controlling the frequency of aeration enables the cleanup crews to
control the amount of oxygen that is involved in the degradation
process.
They also control the moisture content of the soil by irrigation and
spraying.
They are able to control the pH of the soil on the bed by adding
crushed limestone. This crushed limestone helps to form a buffer.
Usually, these beds are in an enclosure. This prevents any inclement
weather from affecting the degradation of the contaminants. It also
helps to contain any evaporated contaminants.

20. Biopiling
The contaminated soil is excavated and put into pills. These piles are
usually 2-3 m in height and are placed over an aeration system.
This system pulls air through piles of contaminated soil by means of a
vacuum pump. This movement of air not only provides O2 to the
microorganisms but also pulls some of the contaminants out of the soil as
it passes through soil.
Optimal bioremediation conditions are maintained by controlling
moisture and nutrient levels. Another form of control is the placement of
the piles into enclosures. This prevents unwanted weather changes and
helps to control any temperature changes.
These piles also require space but they do not need as much space as
landfarming. It is a short term technology that usually only operates for a
few weeks or a few months.

21. 3. Composting
Composting involves first the excavation of the contaminated soil
then a bulking agent is added to the contaminated soil, which is
known as compost material.
Bulking agents includes; hay, straw and corn cobs. These make it
much easier to maintain the maximum rate of degradation of the
contaminants.
The bulking agents allow the cleanup crews to easily control the
amount of water and air that are available to the microorganisms
involved in the degradation reaction.
There are three methods of composting that are used.

22. Static pile composting: This involves the formation of piles &
aerating them by means of a blower or a vacuum pump.
Mechanically agitated in-vessel composting: This involves the
compost material being placed in a vessel. Here, it undergoes mixing
and aeration.
Windrow composting: This method involves placing the compost
material into windrows (long piles as in a farmer's field). This
windrows are then mixed up thoroughly by tractors and other such
equipment.
Windrow composting is the most common method, because it is the most
cost-effective method.

23. Slurry Phase
The contaminated soil is excavated from the site as completely as
possible and put into large tanks known as bioreactors.
These bioreactors are used to mix the contaminants and
microorganisms.
This mixing process keeps the microorganisms in constant contact
with the contaminants. Water, oxygen and nutrients are also added.
Since the cleanup crews have complete control of the conditions in
the bioreactor, they can adjust things until they achieve the optimal
conditions for the degradation of the contaminants.
Since the degradation can be kept at or very close to optimal
conditions, it does not take very long time to break down the
contaminants.

25. Advantage & Disadvantage
Advantages
In fact, slurry phase bioremediation is much faster than many other bioremediation
techniques.
It is very useful in cases in which the contaminants need to be broken down very
quickly.
Another advantage to slurry phase bioremediation is the fact that it can be a
permanent solution to the problem.
Disadvantage
The rate of treatment is limited by the size of the bioreactor. That is, if a small
bioreactor is being used, the rate of degradation will be very slow.
Additional treatment and disposal of the waste water is required. These additional
requirements increases the cost. They are part of the reason that slurry phase
bioremediation has a high operating cost as well as a fairly high capital cost.

26. Bioremediation makes effective better approach possible. Either by
destroying or render them harmless using natural biological activity.
Advantages
Relatively low cost
Low technology techniques
Generally has general public acceptance
Can often be carried out on site, no excavation, no transport.
Drawbacks
May not be effective on all contaminants
Time duration – relatively long
Expertise required to design and implement, although not technically
complex.

27. Biological oxygen demand (BOD)
BOD measure of the quantity of oxygen consumed by
microorganisms during the decomposition of organic matter.
BOD is the most commonly used parameter for determining the
oxygen demand on the receiving water of a municipal or industrial
discharge.
BOD can also be used to evaluate the efficiency of treatment
processes and is an indirect measure of biodegradable organic
compounds in water.

28. Classification
BOD can be Classified into two parts-
Carbonaceous oxygen demand
Nitrogenous oxygen demand.
Carbonaceous oxygen demand
Result of the breakdown of organic molecules such a cellulose and sugars into carbon
dioxide and water
Nitrogenous oxygen demand
Result of the breakdown of proteins.
Proteins contain sugars linked to nitrogen.
After the nitrogen is "broken off" a sugar molecule, it is usually in the form of
ammonia, which is readily converted to nitrate in the environment.
The conversion of ammonia to nitrate requires more than 4 times the amount of O2
as the conversion of an equal amount of sugar to CO2 and water.

29. Methods for BOD measurement
The rate of O2 uptake by microbes in sample at 20ºC and over a
period of 5 days in dark, can be measured by two widely used
methods
Dilution method
Manometric method
Dilution method
It is standard method conducted by placing portions of the sample
into bottles and then completely filled with dilution water which
contains a known amount of dissolved oxygen, freed of air bubbles,
sealed and allowed to stand for five days at a controlled temperature
of 20°C (68 °F) in the dark. After five-days, the remaining dissolved
oxygen is measured.

30. Manometric method
Measurement of BOD is easier.
Oxygen consumed is measured directly rather than with chemical
analysis.
Sample is kept in a sealed container fitted with a pressure sensor A
substance that absorbs CO2 (typically lithium hydroxide) is added in
the container above the sample level.
Stored in conditions identical to the dilution method
The pressure inside the container decreases because CO2 is absorbed.
From the drop of pressure, the sensor electronics computes and
displays the consumed quantity of oxygen.
Advantages:
Simplicity, direct reading of BOD value, continuous display of BOD

31. Chemical Oxygen Demand
In environmental chemistry, COD test is commonly used to
indirectly measure the amount of organic compounds in water.
COD test predicts the O2 requirement of the effluent and is used for
monitoring and control of discharges and for assessing treatment
plant performance.
Using potassium dichromate:
Potassium dichromate a strong oxidizing agent under acidic
conditions. Acidity is usually achieved by the addition of H2SO4.
In the process of oxidizing the organic substances, potassium
dichromate is reduced, forming Cr3+
.
The amount of Cr3+
is determined after oxidization is complete and is
used as an indirect measure of the organic contents of the water
sample.

32. BLANK: it is important that no outside organic material be accidentally added to
the sample to be measured
To control this, blank sample is used
Blank is created by adding all reagents (acid & oxidizing agent) to a volume of
distilled water
COD is measured for both and the two are compared
COD of blank - COD of sample
An excess amount of potassium dichromate (or any oxidizing agent) must be
present
Once oxidation is complete, the amount of excess potassium dichromate must be
measured to ensure that the amount of Cr3+
can be determined with accuracy
To do so, the excess potassium dichromate is titrated with ferrous ammonium
sulfate (FAS) until all of the excess oxidizing agent has been reduced to Cr3+
.

33. The oxidation-reduction indicator Ferroin is added during this
titration step
The Ferroin indicator changes color from blue-green to reddish-
brown, once dichromate is reduced
Calculations
COD = 8000(b-s)n / sample volume
where b is the volume of FAS used in the blank sample, s is the
volume of FAS in the original sample, and n is the normality of FAS
COD = (C/FW)(RMO)(32)
Where C = Concentration of oxidizable compound, FW = Formula
weight of the oxidizable compound, RMO = Ratio of the # of moles
of O2 to # of moles of oxidizable compound in their reaction to CO2,
water and ammonia