Assignment 1B: Me, My Thoughts and I

Me, My Thoughts and I
16th July 2010

0900-1100

Nowadays, our green environment had been polluted and the fact is that pollution is caused by man-made such as open burning, cut down trees, throwing rubbish into the river and so on. As the world is getting more densely populated, it may lead a lot of natural disaster to the world. Open burning will releasing a lot of carbon monoxide and carbon dioxide which can cause air pollution and acid rain. The earth becomes more heaters and raises the water level. In a fact, the water level surrounding Penang Island gradually increases as people wait anxiously in their Polarshift and Other Natural Disaster Organisation Kit (PONDOK). Finally, the water level hits the PONDOK bases and all people had to survive in their PONDOK at least 40 days. After 40 days, it’s the time to start the reconstruction of Penang and we have to save our motherland.First of all, we have carry out afforestation planning by replant the entire tree and replenish the building using biodegradable resources as we can. Nevertheless, we also have to avoid using some material which cannot be recycled such as polystyrene, plastic and so on. In the year of 2005, scientist had found that there are plastic can be degraded itself known as biodegradable plastic and other biodegradable product such as starch plastic, flood prevention bag, bio based cutlery and so on.

Vegetable oil as a main source to produce biodegradable product.. Palm kernel oil, crude palm oil and palm acid oil were using as carbon source for the synthesis of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) by a mutant strain of Wautersia eutropha harboring the Aeromonas caviae polyhydroxyalkanoate (PHA) synthesis gene. Palm oil and soybean oil are most suitable and often used as core substances for PHA production due to their abundance worldwide. Furthermore, both of these oils are renewable nature which is environmentally friendly and easier to find because of the largest sources of vegetable oil. However, scientist had found that palm kernel oil is an excellent carbon source for the synthesis of large quantity of --- by the recombinant w.eutropha harboring the a.cavie PHA synthase gene and more expensive compared to the palm oil and soybean oil.

Polyhydroxyalkanoates (PHAs) are bacterial polymers that are formed as naturally occurring storage polyesters by a wide range of microorganisms in the presence of abundant carbon resources. The assimilated carbon source is biochemical processed into hydroxyalkanoate units, polymerised and stored it in the form of water insoluble inclusions in the cell cytoplasm. PHA synthase act as a key enzyme for the polymerisation process to occur and this microbial polyester is a crystalline thermoplastic with properties upon isolated. Due to inert and durable, plastic had found widespread use in our life. Compared with commodity plastics, PHA is produced from renewable resources which can ensure a sustainable ‘green chemistry processes’ and compatible with our natural ecosystem. This had been shows that PHA as a potential substitute for petrochemical-based plastic.

Besides, PHA known as biodegradable plastic due to it is environmentally friendly and it can biodegradable in landfill, compost and aquatic system. . Biodegradability is the ability of material to be utilized as a carbon source by microorganisms and converted safely into carbon dioxide, biomass and water. The procedure is performed in an anaerobic digester environment that represents highly anaerobic environmental conditions analogous to that of a Landfill. Various investigations found that water content and temperature is important along with the microbial activity while biodegradation, the enzymology of the process, and the important of polymer composition can influence by the environmental factor. In aquatic ecosystem, plastic articles made from PHA will be degraded even under extreme condition such as seasonal change of the oxygen concentration from anoxic to oxic, low temperature, high hydrostatic pressure, no sunlight and so on.

Furthermore, PHA can be produced by biotechnological processes under controlled conditions. Microorganisms are able to incorporate up to 60 different type’s monomer into their storage polymer resulting in various physical properties that range from highly crystalline materials to strong elastomers. By controlling the monomer composition of PHA, the degradation rate can be indirectly controlled. Moreover, many biodegradable polymers that come from renewable resources (i.e., starch-based, PHA, PLA) also compete with food production.

Biodegradable and biocompatible poly (3-hydroxybutyrate)(PHB) and its copolymers with 3-hydroxyvalerate (PHBV) are the best known representatives of PHA family. The biopolymer poly-3-hydroxybutyrate (PHB) is a polyester produced by certain bacteria processing glucose or starch. Its characteristics are similar to those of the petro plastic polypropylene. PHB is distinguished primarily by its physical characteristics. It produces transparent film at a melting point higher than 130 degrees Celsius, and is biodegradable without residue. These polyester such as PHB and PHBV are environmental friendly polymer and had been attracted widespread attention which can be used in a wide range of agricultural, industrial, and medical application Over the past years, PHAs, particularly PHB, have been used to develop devices including sutures, repair devices, repair patches, slings, cardiovascular patches, orthopaedic pins, adhesion barriers, stents, guided tissue repair/regeneration devices, Particular cartilage repair devices, nerve guides, tendon repair devices, bone marrow scaffolds, and wound dressings. Moreover, the capability of PHB for encapsulation and controlled release of different drugs allows applying
PHB for development of therapeutic systems of sustained drug delivery.

There are a lot of advantages of using biodegradable plastic which is from natural materials, such as vegetable crop derivatives or animal products since it was the plastics that will decompose in natural aerobic and anaerobic environments. It was not net gain carbon dioxide emissions and given the evidence by sequesters carbon dioxide during the phase when they're growing and release carbon dioxide when they're decomposing. Biodegradable plastics also can degrade to the point where microorganisms can metabolize them. Other than that, biodegradable bioplastics are used for disposable items, such as packaging and catering items. It’s also often used for organic waste bags because they can be composted together with the food or green waste.

Below are the examples of biodegradable product :

a) Bio based cutlery
The utensils made out of this bio-based and biodegradable polymer resins are compostable. The materials made out of these resins are easy to handle and can withstand heavy heat by retaining its shape. Hence, we can have chances to save our mother land and green environment by using biodegradable cutlery because it can convert your disposables to compassable one.

b) Biodegradable plastics
Biodegradable plastics are plastics that will decompose in natural aerobic and anaerobic environments and it can be achieved by enabling microorganisms in the environment to metabolize the molecular structure of plastic films to produce an inert humus which is the material that is less harmful to the environment.. It also involved in corrosion prevention and plays an important role in aiding the collection and source separation of organic waste. These fully biodegradable and compostable plastics can be used as compost bags or bin liners for food waste collection which is difference compare to the bags made of regular polyethylene, bags made of compostable plastics do not interfere with the composting process.

c) Flood-preventing bag
Flood-preventing bag is made of "Super absorbent polymer" and it was packing in gunny sack of poly-weave bag. It is light in weight, easy to store and convenience to transport. It can be also used to build military bunker and supply with different sizes of flood-preventing bags. This synthetic material is non-toxic, tasteless, not melt into the water and hard to burn. When contact with water, it can expand very quickly to reach about 400 times of the original volume and increased in weight after 2-3 minutes. Thus the water-stopping bag can achieve the purpose of flood-prevention, rescue emergency and block loopholes.

d) Starch plastic
Starch as our original material, through a patented decompose & re-compound technique to produce this plastic material as the replacement of common plastic. It could be degraded above 80% within 3 months in natural environment with sunshine and water, which with exactly the same strength and appearance with plastic and the cost is lower than common plastics. Besides, we also can use this material to produce flower pot, natural vegetable plant pot, cloths rack and so on.