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Biodegradable Bottle - Biodegradation and Breakdown

What is biodegradation?

Biodegradtion is the secretion of acids by microbes which break down the molecular structure and emit either methane gas or CO2 and leave behind highly nitrous soil. The entire mass must be broken down into these three things to be considered biodegradable

How do plastics biodegrade?

The first thing to keep in mind when answering this question is that everything on the planet is made from atomic particles.  Even things that are considered "man made" utilize atomic particles that were and always will be here on the planet.  Plastics are no different and in fact most plastics are hydro-carbons meaning they are made mostly from hydrogen and carbon atoms.  Plastics have been designed for their properties to keep out oxygen so that the food product inside is preserved from naturally biodegrading/rotting. 

Oxygen is an extremely permeable atom and can make its way into just about any type of barrier (including plastics).  Plastics used in the beverage industry is Poly(ethylene terephthalate) PET which has been designed to have an extremely tight chemical bond. 

The other aspect to keep in mind is that everything on the planet will decompose and biodegrade over time.  Microbes are found all over the planet in every aspect of our lives and are constantly breaking things back into their atomic parts.  This is also true for plastics although plastics have been engineered to be very strong which is why it takes hundreds of years for microbes to break plastic back into biogases and/or biomass. 

The technology behind ENSO bottles is an additive which is added into the PET resin during the manufacturing process. The ENSO additive adds organic compounds which hydrostatically bonds to the PET molecules.  Because we are not changing the PET bonds we are not changing the chemical structure, which allows the bottles to maintain the same beneficial physical properties of the PET used.

ENSO bottles do not begin to biodegrade until the plastic is placed into a highly microbial environment i.e. landfill.  Once placed in a microbial environment the ENSO additive has a microbial attractant to help facilitate microbial colonization on the plastic and a swelling agent which opens the PET bond to allow completed biodegradation of the plastic polymer.  Once microbes have colonized on the plastic they begin to break down the PET bond through atomic reorganization to use some of the atoms as energy and leaves behind either methane (anaerobic) or CO2 (aerobic) and inert humus based on the environment the bottle is placed into.  Having the plastic biodegrade from microbial digestion is the natural process of everything and does not leave behind any polymer residue or toxic materials.

What is a Microbe?

A microbe or microorganism are the smallest organisms on the planet and requires the use of a microscope to see them.  There is a huge variety of organisms in this section. They can work alone or in colonies. They can help you or hurt you. Most important fact is that they make up the largest number of living organisms on the planet. There are trillions of trillions of trillions of microbes around the Earth.  Microbes include bacteria, fungi, some algae, and protozoa.  A microorganism can be heterotrophic or autotrophic. These two terms mean they either eat other things (hetero) or make food for themselves (auto). Think about it this way: plants are autotrophic and animals are heterotrophic.  They can be solitary or colonial. A protozoan like an amoeba might spend its whole life alone, cruising through the water. Others, like fungi, work together in colonies to help each other survive.

Isn’t composting the only form of biodegradation?

 No!  There is much confusion about the term biodegradation and several organizations that support the PLA industry uses the term to state that composting is the only form of biodegradation.  The ASTM defines biodegradable plastics as “a degradable plastic in which the degradation results from the action of naturally-occurring micro-organisms such as bacteria, fungi, and algae”.  Biodegradation through naturally-occurring micro-organisms happen in both aerobic (compost) and anaerobic (landfill) environments.

What is the difference between biodegrading and composting and degradable?

Biodegradation:  when plastic (or any other material) degrades from the action of naturally occurring microorganisms, such as bacteria, fungi over a period of time.  Biodegradation can occur in either aerobic (with oxygen) or anaerobic (without oxygen) environments.   

Compostable:  is "capable of undergoing biological decomposition in a compost or aerobic environment to the point that the plastic is not visually distinguishable and breaks down to carbon dioxide, water, inorganic compounds, and biomass”.   In order for a plastic to be called compostable, three criteria need to be met:

  1. Biodegrade - break down into carbon dioxide, water, and biomass.
  2. Disintegrate - the plastic is indistinguishable in the compost, it is not visible and does not need to be screened out
  3. Eco-toxicity – After decomposition no toxic materials are produced and the compost can support plant growth.

For a definition of biodegradable see the explanation at the beginning of this section.

Degradable: means the plastic is only broken down or fragments into smaller and smaller pieces and will never completely disappear.  Degradation can be initiated by oxygen, ultra violet light or heat.  In many cases these products begin to degrade the moment they are manufactured which leads to a shortened useful life.

What is Aerobic and Anaerobic Biodegradation?

Aerobic biodegradion is the breakdown of organic matter by microorganism when oxygen is present.  Anaerobic biodegradation is the breakdown of organic matter by microorganism when oxygen is not present.

Read more - Aerobic Anaerobic Biodegradation

Is the biodegradation process of ENSO bottles strictly anaerobic/aerobic or a combination of both?

It is a combination of both aerobic (with oxygen) and anaerobic (without oxygen).  Microbes found in both environments will be attracted to the ENSO bottle and will colonize on the plastic which will result in complete biodegradtion.

What activates the biodegradation process in an ENSO bottle?

There are three types of microbial environments; suspended, dormant, and active.  ENSO bottles require an active microbial environment in order to break down.  In most environments such as warehouses, offices, store shelves the microbial environment would be suspended or dormant and would not be considered an active microbial environment.  An active microbial environment is one that would have visible fungus and bacteria and would be extremely dirty in either aerobic or anaerobic conditions.  This allows the microbes to colonize on the bottle and begin to digest the polymer.

What is considered a high microbial environment?

An active microbial environment is one that would have visible fungus and bacteria and would be extremely dirty in either aerobic or anaerobic conditions.  Environments such as warehouses, offices, store shelves the microbial environment would be suspended or dormant and would not be considered an active microbial environment.

What prevents ENSO bottles from degrading while in inventory or on the shelf?

In most environments such as warehouses, offices, store shelves the microbial environment would be considered suspended or dormant and would not be fall under an active microbial environment which is needed for the ENSO bottles to activate.  An active microbial environment is one that would have visible fungus and bacteria and would be extremely dirty in either aerobic or anaerobic conditions. 

The microbes required to digest ENSO bottles are readily found in waste areas (compost environments, landfills, lakes, oceans, side of the road, etc.) these microbes are not found on store shelves or warehouse type environments.

How long does it take for an ENSO bottle to biodegrade?

There are a number of factors which contribute to the length of time required to fully biodegrade.  These include the surface area of the plastic, the mass of the plastic, the thickness of the bottles, the microbial activity, oxygen or lack of oxygen, etc.  For example a bottle with smooth surfaces will biodegrade slower than if the bottle had groves. 

The latest ASTM D 5511 laboratory test results show that ENSO bottles in a perfect anaerobic environment will fully biodegrade in 250 days.  In microbial environments such as found in landfills and composting environments biodegradation will take longer.

What are the stages of biodegrdation in a landfill environment?

Aerobic Phase (first few days) – This is the phase when aerobic microbes are becoming established and moisture is building up in the refuse. While standard plastic absorption capability is relatively small, the additive causes further swelling, weakening the polymer bonds and creating molecular spaces where moisture and microbial growth can rapidly begin the aerobic degradation process. Oxygen is replaced with CO2.

Anaerobic, Non-mothanogenic Phase (roughly 2 weeks to 6 months) - After oxygen concentrations have declined sufficiently the anaerobic processes begin. During the initial stage (hydrolysis), the microbe colonies eat the particulates, and through an enzymatic process, solubilize large polymers down into simpler monomers. The secreted monomers mix with the organic additive, causing additional swelling and opening of the polymer chain and increased quorum sensing This further excites the microbes to increase their colonization and consumption of the polymer chain. As time progresses, acidogenesis occurs where the simple monomers are converted into fatty acids. CO2 production occurs rapidly at this stage.

Anaerobic, Methanogenic Unsteady Phase (6 to 18 months) - The microbe colonies continue to grow eating away at the polymer chain and creating increasingly larger molecular spaces. During this phase, acetogenesis occurs where fatty acids are converted into acetic acid, carbon dioxide and hydrogen. As this process continues, CO2 rates decline and H2 production eventually ceases.

Anaerobic, Methanogenic Steady Phase (1 year to 5 years) - The final stage of decomposition involves methanogensis. As colonies of microbes continue to eat away at the remaining surface of the polymer, acetates are converted into methane and carbon dioxide, while hydrogen is consumed. The process continues until the only remaining element is humus. This highly nutritional soil creates and improved environment for the microbes and enhances the final stage of decomposition.

When an ENSO bottle breaks down into biomass, what makes up that biomass?

Biomass is essentially organic matter similar to soil or dirt.  There are no toxic products within that biomass and what remains is basically microbial poop.

What are the typical bacteria strains that feed off of the ENSO additve?

There are plastic consuming microbes that consume plastic regardless of whether it contains the ENSO additive or is traditional plastics.  The specific microbes for consuming plastics have taken years to identify and are considered confidential information within ENSO Bottles.

Won’t microbes consume and digest traditional plastic?

Yes, microbes are very similar to other organisms in that they move to areas where food and other necessities are available or plentiful.  Traditional plastics do not pose a good food source for microbes so they don’t colonize on the plastic.  Microbes which find their way onto traditional plastic will begin to consume it but it is not a plentiful and easily accessible food source so the microbes move to areas which are.  Microbes need to have a plentiful food source and be able to control their environment for PH levels and perform quorum sensing so they multiply and colonize.

Plastics biodegrade from plastaphilic microbes which are in existence all around us, the amount of time for these plastaphilic microbes to eat the carbon matter is a very long time.  Many scientists estimate the time required for biodegradation of plastic to be somewhere around 500 years.

What is microbial quorum sensing?

Microbes use quorum sensing to coordinate certain behaviors based on the local density of the bacterial population.   Microbes that use quorum sensing constantly produce and secrete certain signaling molecules (called autoinducers or pheromones). These microbes have a receptor that can specifically detect the signaling molecule (inducer). When the inducer binds the receptor, it activates transcription of certain genes, including those for inducer synthesis.  As the microbial population grows the concentration of the inducer passes a threshold, causing more inducer to be synthesized. This forms a positive feedback loop, and the receptor becomes fully activated. Activation of the receptor induces the up regulation of other specific genes, causing all of the cells to begin transcription at approximately the same time. This coordinated behavior of microbial cells can be useful in a variety of situations such as multiplying.

Read more – http://en.wikipedia.org/wiki/Quorum_sensing

Is microbial digestion consuming the entire PET chain vs. the ENSO additive?

Tests have been completed to show that biodegradation is occurring on the entire polymer chain vs. just consuming the ENSO additive.  During the ASTM biodegradation testing biodegradation shows over 11% in 30 days.  The ENSO additive is added at a load rate of 1% with the active ingredients being .37%.

What happens to ENSO bottles that end up in a road side ditch?

Biodegradation of ENSO bottles will occur anywhere there is an active microbial environment.  Sitting on the dirt next to the road will subject the bottle to an active microbial environment; however the entire bottle will not be subjected to the microbial environment simultaneously and will result in a much longer biodegradation period.

Do microbes break down the terephthalic acid in PET?

Yes, the terephthalic acid which is made of the benzene ring with the carbon double bond to an oxygen atom will break down from microbial digestion in either an aerobic or anaerobic environment.



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