Anaerobic digestion is emerging as a way to generate sustainable energy from food waste while also addressing the issue of food waste. The global market for anaerobic digesters was nearly $4.5 billion in 2013 and is projected to reach $7 billion by 2018. Research is exploring using biogas from anaerobic digestion as a feedstock for producing bioplastics in a closed resource loop. Studies have shown the technical feasibility of generating bioplastic resins from biogas and current companies are implementing this approach.

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Trending: Energy from Waste
In the larger context of growing global interest in sustainable energy generation, anaerobic digestion (AD)
technologies have experienced strong growth in Europe and Asia, and are emerging in Africa and North
America. Part of what makes AD compelling is that it addresses not only the renewable energy challenge but
also the significant issue of food waste by using this waste as a system input. The value of the global market
for anaerobic digesters and landfill gas equipment is estimated at nearly $4.5 billion for 2013. The market is
projected to reach $7 billion by 2018, growing at a compound annual growth rate (CAGR) of 9.4% over the
five-year period from 2013 to 2018[1]
.
The food waste that can serve as an input for AD processes is often comingled with packaging waste. As
discussed in the first white paper in this series – Anaerobic Digestion: Food & Packaging Waste Are Resources
– exciting opportunity exists to explore packaging material designs that facilitate disposal via AD so as to
simplify diversion of both food and packaging wastes from landfill. Added to this is the underdeveloped
approach of using the very biogas generated by the AD process as feedstock for the manufacture of new
packaging materials.
Bioplastics From Biogas
Understanding the feasibility of generating bioplastic resin from AD-produced biogas is a stated research
objective of the biogas industry. Besides the existing uses for biogas – ranging from power generation to
transportation fuel – use of biogas as a feedstock for the production of bioplastics has the potential to:
 Expand the market for biogas  improve payback for AD installations
 Close the resource loop for relevant packaging materials that are or could be purchased by current AD
customers
 Decrease AD customers’ spend on packaging items for which biogas can be used as production
feedstock
Bioplastics from Biogas – A View of Current Capabilities
Jay Edwards, Pack2Sustain February 2015

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An illustration of the closed resource loop is given here. In addition to material conservation and potential
financial efficiencies, adopters of this approach would be able to communicate a very compelling message to
consumers about use of packaging made from both reclaimed food and reclaimed packaging:
Craig S. Criddle et. al. have indicated the technical feasibility of this approach in U.S. patent application US
20130071890 A1. The methods they describe for the production of bioplastic using biogas are particularly
attractive given that:
 Purification of the biogas produced in an AD process is not necessary prior to introduction into the
fermenting / bioplastic production process
 Use of food scraps & food processing wastes as raw materials are explicitly discussed
 There is the potential to run the process independently, without additional energy inputs
o It would seem that diversion of biogas from the feedstock stream to power the process would
naturally affect yield, however
The diagram below is part of the published patent application, and provides an overview of the process, its
inputs and its products. Following the diagram is a written description of the process as given in the patent
application.
Food Packaging
Anaerobic
Digestion w/ Food
Waste
Biogas ProdutionBioresin Generation
Conversion to
Packaging
Components

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“Production of bioplastic from biogas requires a biogas feed system, a primary fermenter for growth of
aerobic methanotrophic bacteria capable of biopolymer production and a secondary fermenter in which
bioplastic production is induced in the presence of methane. In the primary fermenter, biogas methane,
oxygen, and all of the required nutrients for growth are provided to enable rapid cell division. In the
secondary fermentation, methane and oxygen are provided, but one or more of the remaining nutrients
needed for growth are removed to induce bioplastic production. Bioplastic accumulates as granules inside
the cells. The bioplastic-rich biomass is sent to a thickening device (belt press, dissolved air flotation device,
etc.) to remove most of the water.
Bioplastic production is followed by lysis of the cells to release the bioplastic granules from the cells. In the
preferred embodiment, lysis is achieved without use of solvents or surfactants. Heating, sonic or electrical
pulses, enzymes, or phage may be used to break the cells and release the granules from the cells. In the
case of osmophilic methanotrophs, differences in osmotic pressure may be used to break the cells. The
bioplastic is then separated from the remaining biomass and purified using one of several methods,
including centrifugation to recover a biopolymer pellet, solvent extraction with solvent distillation and
reuse, supercritical fluid extraction, and selective dissolution of residual biomass with sodium hypochlorite
solutions. The biomass residuals are returned to the anaerobic digester for conversion into biogas.”[2]

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Current Application, Future Opportunities
Fortunately, production of bioplastics from biogas has progressed from demonstration to implementation.
San Francisco start-up Mango Materials was founded in 2010 with the mission of “produc[ing]
biodegradable plastics from waste biogas (methane) that are economically competitive with conventional
oil-based plastics.”[3]
Mango Materials currently sources its biomass from a wastewater treatment plant.
Concerning their pricing claim, production cost challenges have long been a hurdle to more sustainably-
sourced plastics, but Mango seems to have directional support in the study Bacterially Produced
Polyhydroxyalkanoate (PHA): Converting Renewable Resources into Bioplastics, which in part explores
some of the economic context of PHA production. Specifically:
“Each year, a large amount of waste materials are discharged from agricultural and food processing
industries and these wastes represent a potential renewable feedstock for PHA production. Utilizing
these waste materials as carbon sources for PHA production not only reduces the substrate cost, but
also saves the cost of waste disposal.” [4]
The application of bioplastics in the field – compostable or digestible – would naturally require development
work to match the packaging material to the product; namely to the food products relevant to the current
discussion. Pack2Sustain’s Custom Technology Scoping work is an opportunity for resource-constrained
organizations to assess packaging options using a firm with decades of commercialization experience. As our
network of industry leaders continues to grow, this service becomes all the more powerful.
Particularly in the foodservice environment, anaerobic digestion presents a significant opportunity to manage
food and packaging wastes in a way that generates the multi-use resource of biogas. To the crucial advantage
of landfill diversion of these wastes, AD’s generation of biogas adds renewable energy and renewable-
material-sourcing benefits. To discuss this topic further, connect with Pack2Sustain today.
[4] Yu J. Microbial production of bioplastics from renewable resources. In: S. T. Yang editor. Bioprocessing for value-added products from
renewable resources; 2007
Acknowledgement: A special thanks to John Baldus at Bioferm Energy Systems, Viessmann Group for his assistance in the preparation of this paper
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