The Challenge: Waste Mountains

Waste is a major byproduct of our free market society. Every year, over 3 billion tonnes (Gt) of waste are produced within the European Union [http://ec.europa.eu/environment/waste/]. This includes municipal solid waste (MSW), industrial and hazardous waste. Of this waste, 10% is plastic. Even more significantly, this represents only a fraction of the world's population, approximately 500 million live within the EU. When we look at the American figures, we see that solely industrial waste comes to around 7.6 Gt [http://www.epa.gov/wastes/nonhaz/industrial/guide/], and this figure was from the 1980s, since then it has no doubt increased per capita as it has in Europe. Frighteningly, this value does not incorporate the global waste production, which since the rise of China has expanded hugely. WASTE Breakdown image

Where does it end up?... landfill and incineration

Sisis simplyfied end of life image perhaps

Recycling is not 100% We cannot recycle everything

The world isn't read for biodegradable plastics, yet...

"when the new generation of biodegradable plastics are included in general plastic wastes, they can contaminate the waste and as a result render it unsuitable for current recycling technologies." Guardian 2013 (http://www.theguardian.com/environment/2013/sep/20/plastic-bags-symbol-waste-recycling) Much of this waste is sent to landfill. If even a fraction of this were successfully degraded and purified, this would provide both metabolites and feedstock for the production of existing petrochemical plastics and bioplastics in our bacteria. We plan to grow our E. coli within bioreactors together in order to breakdown mixed plastics into their component monomers. In so doing, we will circumvent existing problems in recycling technologies that are thwarted by contamination by even minute concentrations present in a non-pure plastic.

References <p>[1] http://ec.europa.eu/environment/waste/

[2] http://www.epa.gov/wastes/nonhaz/industrial/guide/

The Waste Issue

Due to the necessities of living we are always going to produce waste. Couple this with a human population of over 7 billion and increasing consumerism around the world and this waste really starts to add up. Here we explain the extent of the issue and how our system helps to tackle it.

A World of Waste

Each year over four billion tonnes of solid waste - hazardous, industrial and municipal is produced within Europe. We have estimated that between 2005 to 2050, enough waste will be produced to create a mountain half the size of Everest. Plastic waste alone, at ten percent of the total will produce a mountain the size of Mont Blanc, the largest mountain in the EU. Plastic waste is a particular problem due to its seemingly infinite lifetime in the environment and issues with recycling it when it is mixed with other materials. The best known results of plastic accumulation are its harmful effects on marine life. However it can also break down into small pieces and toxic byproducts as well. The mismanagement of waste is not only leading to severe environmental problems but social ones also. The shipping of waste around the world is a disturbing problem but one that makes economic sense. This needs to change.

Europe's new mountain range; Peaks of Waste

Solid Recovered Fuel is our target

If plastics are kept chemically pure and physically separated then they can often be recycled and reused. When they are mixed however with food waste and other items then there are only two end of life solutions, landfill or incineration. Solid recovered fuel(SRF) is one of these mixed wastes. It results from the processes recovering valuable materials from waste in mixed recycling facilities. It consists of all the small fragments of plastic, wood, paper and fibre which are too small to be separated further by the recovery machines. Twenty percent of what enters a recovery facility leaves as SRF. Just one of these recovery facilities in north-west London produces 320,000 tonnes of SRF a year. This is a waste product, costing the facilities millions in disposal and ending up at incinerators where toxic chemicals are released into the atmosphere along with large amounts of CO2. Incineration is a one-time-only affair; the resources which went into the production of these materials are lost to the atmosphere.

Solid Recovered Fuel(SRF) contains finite resources which are currently used inefficiently.

Our Solution

Our system is designed to recover the valuable resources locked up in the non-recyclable mixed waste, transforming it from a waste material into the commodities ethylene glycol and poly-3-hydroxybutyrate; a feedstock for many applications and a useful bioplastic respectively.

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Producing and Recycling Bioplastics

We are producing the bioplastic poly-3-hydroxybutyrate(PHB) using the organic material in the waste product, solid recovered fuel. We have also devised the first method for recycling PHB and are working with Yale to do the same for PLA. Here you will find out why.

Bioplastics have a bright future

Bioplastics are made either directly by living things or from the products they make. They are usually more environmentally friendly than petrochemically derived plastics(1) and do not rely upon finite fossil fuels. Advances in how they are produced is allowing bioplastics with controllable physical properties to be produced(3) which enables uses which mimic those of oil-based plastics. The properties of some bioplastics allow novel functions to be carried out; an exciting example of this is the production of biocompatible scaffolds which can be used in surgical treatments(4). This combination of innovations leading to improved functions and the development of novel uses combined with environmental benefits over petrochemical plastics are just some of the reasons why bioplastics are expected to flourish commercially in the coming years(5). Currently around 10% of the plastics market consists of bioplastics, with this predicted to increase to around 30% by 2020. This is a huge increase and represents significant commercial opportunities. The predicted production of such a large amount of material requires careful consideration of what we do once we have used the products produced, called end of life solutions.

Poly-3-Hydroxybutyrate and Polylactic Acid are two of the best developed bioplastics

Poly-3-hydroxybutyrate(P3HB) and Polylactic Acid(PLA) are both commonly used and well studied bioplastics. Currently several different companies produce each by a variety of methods(9).

Poly-3-Hydroxybutyrate

P3HB is produced as an energy store in some bacteria. Commercially it is produced in bioreactors from sucrose and other sugars derived from plant biomass. P3HB can also be produced in the stems of plants, however this requires large inputs of fertiliser and large areas of land. Interest in the production from the fermentation of organic waste materials is also increasing. P3HBs are being investigated for uses in many things from food packaging to discount cards to replacements for current plastics made from polymer blends.

Polylactic acid

Polylactic acid production is usually a chemical process, building up the monomers of lactic acid or lactide. It can also be produced by certain organisms. Biological systems of PLA production are also possible. This is what our collaborators at Yale are working on. PLA already sees use in the packaging industry and plastic bottles. Future uses as with many ‘biodegradable’ plastics will expand to include tasks where increased durability are needed(8).

Can’t we just let these plastics biodegrade?

You may have heard that P3HB and PLA are biodegradable. The biodegradable label disguises a subtlety which has important consequences. P3HB and PLA are actually industrially fermentable. This means special conditions are required for optimal degradation. One prominent P3HB producer even states during a promotional video that P(3HB) will not biodegrade in conventional landfills and counter to many claims will not easily degrade in your compost heap. PLA can be degraded in a compost heap, however the time it takes varies considerably depending upon the weather, temperature etc. Allowing these plastics to biodegrade is also a waste of the valuable resources used to create them. Biodegradation, although theoretically a green option due to the renewable source of the feedstocks, ignores the large amounts of energy, fertiliser and water that went into their original production. Biodegrading the final product after use means that it must be produced again from scratch. The loss of resources represented by biodegradation and the special conditions required make this the wrong end of life choice for P3HB and PLA.

What other methods for recycling P3HB and PLA are there?

Currently we are are not aware of any technologies available for the recycling of P3HB, that makes this this first.

PLA can be recycled by chemical means, reducing it into the monomer and then re-polymerising it again. However, innovation in recycling methods which tackle some of the key issues facing PLA will be key to its successful increased use. One benefit is the ability to recycle material contaminated with food waste. Currently plastics with more than 10% food waste contamination must be incinerated or landfilled. With biological recycling this would become an asset, helping to feed the bacteria.

Solid Recovered Fuel(SRF) contains finite resources which are currently used inefficiently.; Peaks of Waste

References

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