Bio-substitution involves replacing pollution-causing substances with naturally occurring or biodegradable synthetic alternatives. This can help reduce environmental pollution. Examples of bio-substitution include replacing fossil fuels with biofuels like biodiesel and biohydrogen, and replacing plastic with biodegradable polymers. While bio-substitution requires higher production costs and modification of machines, it provides environmental benefits by reducing pollution and promoting sustainable development.

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INTRODUCTION
To an extend we can reduce the environmental pollution by substituting pollution causing
substances with some naturally available substances or biodegradable synthetic
substances; such substitution is known as bio substitution. For most of the pollution
causing substances like plastic, oils lubricants, etc. we can find suitable less harmful
alternatives or bio-subtituents. Bio-substitution can be considered as an environmental
beneficial application of Biotechnology.
It require more production cost and also it require modification of existing engines or
machines, it’s efficiency is also less in most of the cases when compared with the
conventional systems. In an Environmentalist view bio-substitution is beneficial as it can
reduce pollution potential and also it can promote eco-friendly developments. If we are
considering the impacts of pollution created by our conventional polluting substances we
can very well say that bio-substitution is the better option.
In many areas we can apply the technique of bio-substitution. Some examples are:
 Fossil fuel can be substituted by bio-diesel and bio-hydrogen.
 LPG can be replaced by CNG and biogas.
 Plastic and other non biodegradable polymers can be replaced by biodegradable
polymers or bio-plastics.
 Conventional lubricating oil can be substituted by biodegradable lubricating oil.
 Microbial fuel cells can be used for the production of electricity.

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1-BIO DIESEL: SUBSTITUENT FOR FOSSIL FUEL
Bio diesel or bio ethanol is produced from natural or biological recourses and it can be
used directly in conventional diesel engines. Bio diesel is some times called FAME (fatty
acid methyl ester) or FAEE (fatty acid ethyl ester). It can be produced from edible oils
such as palm oil, soyabean oil, rape seed oil, sunflower oil and some other vegetable oils;
animal fats ( fish waste and slaughter house wastes can be used) and non-edible oils like
jatropha, castor beans, pongamia pinnata.
Advantages of biodiesel
1. Produced from sustainable / renewable biological sources
2. Eco-friendly and oxygenated fuel
3. Sulphur free, less CO, HC, particulate matter and aromatic compounds emissions
4. Income to rural community
5. Fuel properties similar to the conventional fuel
6. Used in existing unmodified diesel engines
7. Reduce expenditure on oil imports
8. Non toxic, biodegradable and safety to handle

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BIODIESEL PRODUCTION
The basic chemical reaction taking place in the production of biodiesel is the trans-
esterification of the oil or fat. This involves the catalytic reaction of the oil or fat with
short-chain aliphatic alcohol. Batch process, super critical process, ultra sonic method or
even microwave method can be used for the transesterification process. By product of
this process is glycerol ( for 1tonn biodiesel 100kg glycerol is produced.
Production of biodiesel from non edible oil is preferable. Eg; from jatropa curcas.
Among the non-edible oil sources, Jatropha curcas is identified as potential biodiesel
source and comparing with other sources, which has added advantages as rapid growth,
higher seed productivity, suitable for tropical and subtropical regions of the world. The
Jatropha plant can reach a height up to 5 m and its seed yield ranges from 7.5 to 12
tonnes per hectare per year, after five years of growth. The oil content of whole Jatropha
seed is 30-35 % by weight basis. Several properties of the plant including its hardness,
rapid growth, easy propagation and wide ranging usefulness have resulted in its spread
far beyond its original distribution. Preparation of bio diesel from jatropha requires a two-
step approach; the extraction of the Jatropha oils from the seed, and the conversion of the
extracted oil to Biodiesel, according to the following transesterification reaction. The
mechanical extraction was done using a hydraulic press. After dehulling, the Jatropha
seeds were first pressed to extract oil and then placed inside a soxhlet and brought into
contact with a condensed solvent. The solvent dissolves the oil and then it is later
separated using a rotor vapor. The obtained Jatropha oil was used for Biodiesel
production. The transesterification reaction was done using methanol and two basic
catalysts. Solvent extraction has higher oil yield than hydraulic press.
The flow chart showing the procedure for production of biodiesel from jatropa curcas is
given below,

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2-BIO HYDROGEN AS FUEL
Hydrogen is the fuel of future which can solve the scarcity of fossil fuel that may come in
to picture in the near future. Combustion of 1g H2 can produce 30000 cal where as
gasoline can produce only 11000cal. There are numerous ways for the production of
hydrogen out of which the biological methods are preferable in an environmental point of
view. The hydrogen produced through biological methods is called as the bio-hydrogen.
METHODS OF BIO-HYDROGEN PRODUCTION
 Dark fermentation
 Photo fermentation
 Combined fermentation
 Direct photolysis (algae)
 Indirect photolysis ( cyanobacteria)
There is a huge potential for improving yield of hydrogen from metabolic engineering.
The bacteria clostridium could be improved for hydrogen production. The photo-
fermentation step in rhodobacter COULD BE improved for the hydrogen production.

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3-BIOGAS AS SUBSTITUENT FOR LPG
Biogas is a fuel produced by a digestion device fed by agricultural, animal or household
waste. The waste is made into a slurry and contained in a tank known as a biodigester or
biogas plant. Not only does the biogas plant produce fuel, it has added benefits of
producing high nutrient fertilizers and also encourages better sanitation. Two main types
of biogas plants are there, floating dome type( eg: KVIC type) and fixed dome type (
janata type). Biogas produced from the plant can be directly used as fuel for cooking
purpose and also the compressed natural gas(CNG) can be used instead of LPG even in
vehicles.

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CASE STUDY
Economic Feasibility Of Substituting LPG With Biogas For MANIT Hostels is a study
on the economic feasibility of substituting LPG with biogas for an Indian University
hostel was done . The University hostels daily generate huge amount of biomass in the
form of kitchen waste. This kitchen waste can be utilized to produce biogas, which can be
further used in the hostel mess as an alternate to LPG. Economic factors for the suitable
bio-digester design and the feasibility of its replacement in the long run have been studied
in this paper.
Economic feasibility of installation of kitchen waste Bio-digester for the hostel mess has
been assessed and was found to be technically and economically viable solution. System
payback is 1-2 years with annual returns of Rs.201915. By the installation of Bio-digester
we can reduce the demand for LPG thereby saving fossil fuels. The installation of
digesters is a better solution for disposal of kitchen waste which also reduces the burden
on the waste processing by Municipalities / Corporations. The slurry produced by the
biogas plants can be used as good fertilizer for the plantation in MANIT.
4- BIOPLASTICS
Plastic is the main threat in modern world, the main problem associated with plastic is
that it is non-biodegradable. If we are able to substitute this conventional plastic with a
biodegradable form it can reduce pollution due to plastic to a large extent. Such plastics,
which are biodegradable and /or bio-based are called as bio plastics.
Biobased, biodegradable plastics
They include starch blends made of thermo-plastically modified starch and other
biodegradable polymers as well as polyesters such as polylactic acid (PLA) or
polyhydroxyalkanoate (PHA). Unlike cellulose materials (regenerate-cellulose or
cellulose-acetate), they have been available on an industrial scale only for the past few
years. So far, they have primarily been used for short-lived products such as packaging
,yet this large innovative area of the plastics industry continues to grow by the
introduction of new biobased monomers such as succinic acid, butanediol, propane diol
or fatty acid derivatives. Several materials in this group, such as PLA, are currently
pointing towards new ways – away from biodegradation and towards end-of-life
solutions such as recycling. The renewable basis of these materials is now at the focus of
attention and technical development. Pilot projects aim to establish recycling processes
and streams. This dynamic development proves, that bioplastics have the potential to
shape the plastics industry, and to produce new future-bound and competitive materials

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PHB (POLY HYDROXY BUTYRATE)
Polyhydroxybutyrate (PHB) is a biopolymer that can be used as a biodegradable
thermoplastic material for waste management strategies and biocompatibility in the
medical devices The commercial production of PHB has been using relatively cheap
substrates such as methanol, beet molasses, ethanol , starch and whey , cane molasses as
a sole carbon source ,wheat hydrolysate and fungal extract or soy cake. Various
nitrogen-rich media, such as casein hydrolysate, yeast extract, typtone, casamino acids,
corn steep liquor and collagen hydrolysate), have been used in PHB bioconversions using
either Cupriavidus necator or recombinant Escherichia coli strains.

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5- BIO POLYMERS
These polymers bring a significant contribution to the sustainable development in view of
the wider range of disposal options with minor environmental impact. As a result, the
market of these environmentally friendly materials is in rapid expansion, 10–20 % per
year. Consequently, biodegradable polymers are the topics of much research.
Biodegradable polymers can be mainly classified as agropolymers (starch, chitin,
protein…) and biodegradable polyesters [polyhydroxyalkanoates, poly(lactic acid)…].
These latter, also called biopolyesters, can be synthesized from fossil resources but main
productions are obtained from renewable resources. This chapter intends to present these
polymers regarding the synthesis, the structure, properties and their applications.

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6- BIO-LUBRICANTS
Bio-lubricants or bio-lubs are bio-based lubricants produced from m a variety of
vegetable oils, such as rapeseed, canola, sunflower, soybean, palm, and coconut oils. The
best application for biolubricants is in machinery that loses oil directly into the
environment during use, total loss lubricants (TLLs), and in machinery used in any
sensitive areas, such as in or near water. Applications for TLLs include two-stroke
engines, chainsaw bars and chains, railroad flanges, cables, dust suppressants, and marine
lubricants. Compared to petroleum-based lubricants, use of biolubricants:
• Produces a cleaner, less toxic work environment and fewer skin problems for those
working with engines and hydraulic systems.
• Offers better safety due to higher flashpoints, constant viscosity, and less oil mist and
vapor emissions.
• Produces fewer emissions due to higher boiling temperature ranges of esters.
• Are highly biodegradable.
• Costs less over the product’s life-cycle due to less maintenance, storage and disposal
requirements.
The use of biolubricants can reduce pollution in stormwater from leaks in engines,
hydraulic systems, and brake lines. Many European countries now require biolubricants
in selected environmentally sensitive areas. The City of Seattle is promoting the use of
biolubricants for bar oil and hydraulics in heavy equipment used in watershed
maintenance.
Since biolubricants outperform petroleum lubricants, less is required per application. Cost
benefits include reductions in environmental and safety penalties in the case of spills, and
less parts wear, maintenance costs, and disposal fees. Biolubricants: • Evaporate slower
than petroleum lubricants. • adhere better to metal surfaces They have several
disadvantages in the use phase of the product life cycle, including: • Some bad odors if
contaminants are present. • High viscosity at low temperatures. • Poor oxidative stability
at high temperatures, although additives designed specifically for plant-based lubricants
eliminate stability issues related to extreme high and low temperatures.

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7-BIOLOGICAL FUEL CELL
Biological Fuel Cells (BioFCs), are devices capable of directly transforming chemical to
electrical energy via electrochemical reactions involving biochemical pathways.Unlike
conventional fuel cells, which employ hydrogen, ethanol and methanol as fuel, biological
fuel cells use organic products produced by metabolic processes.A distinctive feature of
biological fuel cells is that the electrode reactions are controlled by Enzymes or by
Microorganisms. Two types of biological fuel cells are there, microbial fuel cells (MFC)
and enzymatic fuel cells (EFC). A Microbial fuel cell (MFC) is a device that converts
chemical energy to electrical energy by the action of microorganisms.An Enzymatic fuel
cell (EFC) is a device that converts chemical energy to electrical energy by the action of
enzymes. Bio fuel cells are solution for worlds two great issues, fuel crisis and waste
disposal; as it can convert waste into electrical energy.
The working principle of MFC is: when anaerobic bacteria are placed in the specially
designed anaerobic fuel cell they will attach to the cathode. Since the usual electron
accepter, oxygen is not present the electron produced as a result of their metabolic
degradation of the organic waste will transfer into the electrode. These electrons will thus
travel from the anaerobic cathode to the aerobic anode through the membrane. At cathode
electron, oxygen and protons combines to form water.

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CONCLUTION
Bio substitution is harmless solution fuel and energy crisis and also it is a better way to
reduce environmental pollution. Cost of production and the modification of existing
machines are the main problems associated with bio substitution. But if we are
considering the negative impact of these pollutants cost is not a big matter. For example:
Since plastic is non biodegradable and the only way to dispose plastic is incineration it
creates huge problems. Improper Incineration of plastic waste can produce toxic gases
that can effect life and also careless disposal of plastic into land sites can reduce the
quality of soil and also can reduce the permeability of soil. It can effect plant growth in
that soil. If we are considering these adverse effects of plastic, the cost we may have to
spend for the production of biodegradable or bio plastic is less.

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REFERENCES
1. http://www.build-a-biogas-plant.com
2. http://agritech.tnau.ac.in
3. http://www.biogas-india.com
4. Economic Feasibility Of Substituting LPG With Biogas For MANIT Hostels
R. Ananthakrishnan, K. Sudhakar , Abhishek Goyal and S. Satya Sravan
Department of Energy, M.A.N.I.T Bhopal 462051, Madhya Pradesh, India
Department of Electronics & Communication, M.A.N.I.T Bhopal 462051, M.P.,
India
5. http://www.intechopen.com
6. Production and Characterization of Polyhydroxybutyrate from Molasses and Corn
Steep Liquor produced by Bacillus megaterium ATCC 6748 S. Chaijamrus and N.
Udpuay Dept. of Biology, Fac. of Science, Naresuan University, Phitsanulok
65000, Thailand
7. http://2008.igem.org/Team:Utah_State/Project
8. http://www.microbialcellfactories.com
9. Environmentally preferable purchasing fact sheet- bio-lubricant ; department of
ecology, state of Washington