Singapore

Biology Investigatory Project

               

                                By Joe Calvin Rossario

                                                Class XII

Singapore

EFFECT OF BIODEGRADABILITY ON BIOPLASTICS

CBSE Class - XII

                  Academic Year 2016-2017

              Name: Joe Calvin Rossario

              Reg. No: XXXXXXXXXXXX

                                                                                      Mrs. Geetha Narasimman

External Examiner                                                       Teacher in Charge

CERTIFICATE

This is to certify that Joe Calvin Rossario of class XII has prepared the report on the project titled "Biodegradability" in accordance with the guidelines given by Central Board of Secondary Education. The report is found worthy of acceptance as final project report for Biology of class XII during the academic year 2016-2017.

Mrs. Geetha Narasimman

ACKNOWLEDGEMENT

It’s my humble pleasure to thank my Biology teacher Mrs.Geetha Narasimman who gave me the opportunity to do this wonderful project on the topic and also for helping and guiding me throughout the completion of my project. This project has helped me in doing a lot of research enabling me to enhance my scientific skills. 

Joe Calvin Rossario

Class XII

TABLE OF CONTENTS:-

1	Aim
2	Biodegradation-over view      a. Factors affecting rate of biodegradation      b. Biodegradability of plastics
3	Bioplastics - background research             a. Are bioplastics good or bad?       b. How to cut down on plastics       c. Advantages of bio-degradable plastics
4	Experiment –making of biodegradable plastics       a. Hypothesis       b. Materials required       c. Procedure      d. Result
5	Conclusion
6	References

AIM  

To Study of biodegradability and biodegradable plastics

BIODEGRADATION – OVERVIEW

Biodegradation is the disintegration of materials by bacteria, fungi, or other biological means. Although often conflated, biodegradable is distinct in meaning from compostable. While biodegradable simply means to be consumed by microorganisms, "compostable" makes the specific demand that the object break down under composting conditions. The term is often used in relation to ecology, waste management, biomedicine, and the natural environment (bioremediation) and is now commonly associated with environmentally friendly products that are capable of decomposing back into natural elements. Organic material can be degraded aerobically with oxygen, or anaerobically, without oxygen. Bio surfactant, an extracellular surfactant secreted by microorganisms, enhances the biodegradation process.

Biodegradable matter is generally organic material that serves as a nutrient for microorganisms. Microorganisms are so numerous and diverse that, a huge range of compounds are biodegraded, including hydrocarbons (e.g. oil), polychlorinated biphenyls (PCBs), and polyromantic hydrocarbons (PAHs), pharmaceutical substances. Decomposition of biodegradable substances may include both biological and abiotic steps.

FACTORS AFFECTING RATE OF BIODEGRADABILITY

In practice, almost all chemical compounds and materials are subject to biodegradation, the key is the relative rates of such processes - minutes, days, years, centuries... A number of factors determine the degradation rate of organic compounds.  Salient factors include light, water and oxygen. Temperature is also important because chemical reactions proceed more quickly at higher temperatures. The degradation rate of many organic compounds is limited by their bioavailability. Compounds must be released into solution before organisms can degrade them.

Biodegradability can be measured in a number of ways. Respirometry tests can be used for aerobic microbes. First one places a solid waste sample in a container with microorganisms and soil, and then aerate the mixture. Over the course of several days, microorganisms digest the sample bit by bit and produce carbon dioxide – the resulting amount of CO₂ serves as an indicator of degradation. Biodegradability can also be measured by anaerobic microbes

and the amount of methane or alloy that they are able to produce. In formal scientific literature, the process is termed bio-remediation.

Approximated time for compounds to biodegrade in a marine environment
Product	Time to Biodegrade
Paper towel	2–4 weeks
Newspaper	6 weeks
Apple core	2 months
Cardboard box	2 months
Wax coated milk carton	3 months
Cotton gloves	1–5 months
Wool gloves	1 year
Plywood	1–3 years
Painted wooden sticks	13 years
Plastic bags	10–20 years

BIODEGRADABILITY OF PLASTICS

Plastics biodegrade at highly variable rates. PVC-based plumbing is specifically selected for handing sewage because PVC biodegrades very slowly. Some packaging materials on the other hand are being developed that would degrade readily upon exposure to the environment. Illustrative synthetic polymers that are biodegrade quickly include polycaprolactone, others are polyesters and aromatic-aliphatic esters, due to their ester bonds being susceptible to attack by water. A prominent example is poly-3-hydroxybutyrate, the renewably derived polylactic acid, and the synthetic polycaprolactone. Others are the cellulose-based cellulose acetate and celluloid (cellulose nitrate).

Polylactic acid is an example of a plastic that biodegrades quickly.

Under low oxygen conditions biodegradable plastics break down slower and with the production of methane, like other organic materials do. The breakdown process is accelerated in a dedicated compost heap. Starch-based plastics will degrade within two to four months in a home compost bin, while polylactic acid is largely undecomposed, requiring higher temperatures. Polycaprolactone and polycaprolactone-starch composites decompose slower, but the starch content accelerates decomposition by leaving behind a porous, high surface area polycaprolactone. Nevertheless, it takes many months. In 2016, a bacterium named Ideonella sakaiensis was found to biodegrade PET.

BIOPLASTICS - BACKGROUND RESEARCH:-

 

Biodiversity and occurrence of polymer-degrading microorganisms vary depending on the environment, such as soil, sea, compost, activated sludge, etc. It is necessary to investigate the distribution and population of polymer-degrading microorganisms in various ecosystems. Generally, the adherence of microorganisms on the surface of plastics followed by the colonization of the exposed surface is the major mechanisms involved in the microbial degradation of plastics. The enzymatic degradation of plastics by hydrolysis is a two-step process: first, the enzyme binds to the polymer substrate then subsequently catalyzes a hydrolytic cleavage. Polymers are degraded into low molecular weight oligomers, dimers and monomers and finally mineralized to CO₂ and H₂O.

The clear zone method with agar plates is a widely used technique for screening polymer degraders and for assessment of the degradation potential of different microorganisms towards a polymer. Agar plates containing emulsified polymers are inoculated with microorganisms and the presence of polymer degrading microorganisms can be confirmed by the formation of clear halo zones around the colonies. This happens when the polymer-degrading microorganisms excrete extracellular enzymes which diffuse through the agar and degrade the polymer into water soluble materials. Using this technique, it was confirmed that PHB, polypropiolactone (PPL) and PCL degraders are widely distributed in different environments.  Majority of the strains that are able to degrade PHB belong to different taxa such as Gram-positive and Gram-negative bacteria, Streptomyces and fungi . It has been reported that 39 bacterial strains of the classes Firmicutes and Proteobacteria can degrade PHB, PCL, and PBS, but not PLA . Only a few PLA degrading microorganisms have been isolated and identified. The population of aliphatic polymer-degrading microorganisms in different ecosystems was found to be in the following order: PHB = PCL > PBS > PLA .

ARE BIOPLASTICS GOOD OR BAD?

Anything that helps humankind solve the plastics problem has to be a good thing, right? Unfortunately, environmental issues are never quite so simple. Actions that seem to help the planet in obvious ways sometimes have major drawbacks and can do damage in other ways. It's important to see things in the round to understand whether "environmentally friendly" things are really doing more harm than good.

Bioplastics and biodegradable plastics have long been controversial. Manufacturers like to portray them as a magic-bullet solution to the problem of plastics that won't go away. Bioplastics, for example, are touted as saving 30–80 percent of the greenhouse gas emissions you'd get from normal plastics and they can give food longer shelf-life in stores. But here are some of the drawbacks:

• When some biodegradable plastics decompose in landfills, they produce methane gas. This is a very powerful greenhouse gas that adds to the problem of global warming.
• Biodegradable plastics and bioplastics don't always readily decompose. Some need relatively high temperatures and, in some conditions, can still take many years to break down. Even then, they may leave behind toxic residues.
• Bioplastics are made from plants such as corn and maize, so land that could be used to grow food for the world is being used to "grow plastic" instead. By 2014, almost a quarter of US grain production was expected to have been turned over to biofuels and bioplastics production; taking more agricultural land out of production could cause a significant rise in food prices that would hit poorest people hardest.
• Some bioplastics, such as PLA, are made from genetically modified corn. Most environmentalists consider GM (genetically modified) crops to be inherently harmful to the environment.
• Bioplastics and biodegradable plastics cannot be easily recycled. To most people, PLA looks very similar to PET (polyethylene terephthalate) but, if the two are mixed up in a recycling bin, the whole collection becomes impossible to recycle. There are fears that increasing use of PLA may undermine existing efforts to recycle plastics.
• Many people think terms like "bioplastic," "biodegradable," and "compostable" mean exactly the same thing. But there's a huge difference between a "biodegradable" plastic (one that might take decades or centuries to break down) and a truly "compostable" material (something that turns almost entirely into benign waste after a matter of months in a composter), while "bioplastic," as we've already seen, can also mean different things. Confusing jargon hampers public understanding, which makes it harder for consumers to grasp the issues and make positive choices when they shop.

HOW TO CUT DOWN ON PLASTICS

Why is life never simple? If you're keen on helping the planet, complications like this sound completely exasperating. But don't let that put you off. As many environmental campaigners point out, there are some very simple solutions to the plastics problem that everyone can bear in mind to make a real difference. Instead of simply sending                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              your plastics waste for recycling, remember the saying "Reduce, repair, reuse, recycle".  Recycling, though valuable, is only slightly better than throwing something away: you still have to use energy and water to recycle things and you probably create toxic waste products as well. It's far better to reduce our need for plastics in the first place than to have to dispose of them afterwards.

 ADVANTAGES OF BIO-DEGRADABLE PLASTICS

1. Biodegradable plastics take less time to break down
Biodegradable packaging and biodegradable bags take much less time to break down after being discarded, if they haven’t been recycled, of course. What this means is that it gets absorbed in the earth, and there will no longer be tons of plastic dominating our landfills.

2. Biodegradable plastics are renewable
Biodegradable plastics are made from biomass, which is a completely renewable resource. It is an organic compound, which breaks down. There is plenty of it around the globe. Biomass includes trees, plants, grass, and all organic materials that decompose. This may even include animal fats, meats, and other tissues.

3. Biodegradable plastics are good for the environment
Biodegradable plastics are much better for the environment, because there is no harm done to the earth when recovering fossil fuels. Also, in this process there are very few greenhouse gas and harmful carbon emissions. Regular plastics need oil for their manufacturing, which pollutes the environment.

4. Biodegradable plastics require less energy to produce
Biodegradable plastics need less than half the energy to produce than their non-biodegradable counterparts. This means that it is possible to make twice the amount of biodegradable packaging and biodegradable bags using the same amount of energy.

5. Biodegradable plastics are easier to recycle
Biodegradable plastics are created from materials that are fully biodegradable. This means that they can break down much faster and recycling them takes less energy. Biodegradable plastics can be reused more efficiently, which gives them a clear advantage.

6. Biodegradable plastics are not toxic
Traditional plastics are full of harmful by-products and chemicals, which are released during their breakdown process. Biodegradable plastics are completely safe and do not have any chemicals or toxins. This plastic harmlessly breaks down and gets absorbed into the earth. Such advantages of bioplastics are of extreme importance, as the toxic plastic load on the earth is growing and at this rate will cause a whole range of problems for future generations.

7. Biodegradable plastics reduce dependence on foreign oil
The use of biodegradable plastics will decrease the country’s dependence on other countries for fossil fuels. The majority of the oil that is needed to make regular plastic comes from the Middle East, which has not always been friendly toward the U.S. Biodegradable plastics are created from domestic biomass materials, so it reduces the dependence on foreign oil, providing a domestic solution instead.

HYPOTHEISIS

If homemade biodegradable plastic buttons and non biodegradable plastic buttons are buried in soil samples then the biodegradable plastic buttons will break down faster.

MATERIALS REQUIRED

·       Two small clay plant pots

·       Four cups of  soil

·       Small gardening shovel

·       Gardening gloves

·       Five small white plastic buttons (store

·       bought)

·       Five small biodegradable buttons 1/2 cup of water each day

·       To make biodegradable buttons: small non-stick saucepan plastic cooking spoon

·       1/2 cup half and half cream 1 teaspoon of white vinegar pot holder

·       Thick paper towels

·       Coffee cup

·       Aluminium foil

PROCEDURE

Step one: Make Biodegradable Buttons

Ø Pour 1/2 cup of half and half cream into saucepan until cream begins to foam. Remove the cream from the heat.

Ø Add 1 teaspoon of vinegar to cream and stir. The mixture should be clumpy.

Ø Put two paper towels over opening of coffee cup and tuck them inside of the cup.

Ø Carefully pour the clumping cream mixture into the coffee cup and be sure to scrape out all clumps out of the pan.

Ø Allow five minutes for curds to cool, lift the paper towels out of the cup and squeeze out any excess liquid.

Ø Unwrap paper towels and you will see a white cheese like plastic!

Shape several small buttons and place on aluminum.

Ø Wait 24 hours and you will have a hard yellowish natural plastic

Ø Step Two: Bury the Buttons

Ø Be sure buttons are dry and hard.

Ø Fill each clay pot with1 cup of garden soil.

Ø Put five biodegradable buttons in one pot, put 1 cup of soil on top and label

Ø Water pots with1/4 water daily for seven days.

Ø Uncover buttons in both pots and compare.

RESULT

The biodegradable buttons did change in shape, size, colour and consistency.
They were smaller, soft and mushy, bright white and thinner. This proves that biodegradable plastic would break down!

   

Bio-degradable plastics                       Non-biodegradable plastics

CONCLUSION

In conclusion, after seeing how the homemade biodegradable plastic broke down verses the regular non-biodegradable plastic I can clearly see that my hypothesis was correct. I guessed that the biodegradable plastic buttons would break down if I buried them under soil and watered them.

Based on the results of this experiment, I believe that industrial companies should start using biodegradable plastic in the products that they produce because the plastic that is thrown away would break down rather than stay on our Earth.

REFERENCES

Glen. 100 Amazing First Prize Science Fair

http://en.wikipedia.org/wiki/Bioplastic

http://www.search.com/reference/Bioplastic

http://www.explainthatstuff.com/bioplastics.html

Images:

http://www.amaresearch.co.uk/PlasticRecycling_08Web.jpg

http://polyfort.com/images/industry_overview/plastic%20products%20made%20from%20petrochemicals.jpg

http://www.takeprideinutah.org/plastic~kills.html

http://www.cermakrhoades.com/blog/cra_joer.html

http://www.sustainableisgood.com/blog/biobag/

 http://www.odec.ca/projects/2010/whitxb2/index.htm