How Valuable is our Food Waste?

Dan Noakes

By Dan Noakes

06 Nov 2015

Food waste is applicable to everyone. We all create it and we all have a responsibility to reduce it. Roughly one third of global food production for human consumption is lost or wasted amounting to 1.3 billion tonnes per year.

Food waste can be harmful to the environment and human health. If allowed to breakdown in landfill, this can cause methane (a potent greenhouse gas) to be released into the atmosphere. It can also form leachate, which can poison watercourses and drinking aquifers. Meat products also pose a problem, specifically by breaking down into toxic compounds under their own biological activity.

There are many types of food wastes, all comprising a variety of chemical compounds, some which can be easily extracted to create value and some which need converting to something else first. Kerbside food waste can comprise many food types. It may include putrescible wastes (tomatoes, meals etc) and also materials that are challenging to biologically breakdown (banana skins etc.). Catering waste can include anything from plate scrapings to potato peelings and can be massively variable, however the UK is experiencing commercial success in the collection of used cooking oil from restaurants and its conversion into biodiesel for blending with diesel transport fuel.

Where large quantities of a single food type is discarded, such as supermarket supply chains and commercial food manufacture, there is great opportunity for creating significant value through the application of industrial biotechnology. Biological processes use to make a variety of products, which may directly replace or perform better than the products derived from fossil fuel consumed today.

The technology allows for valuable chemical compounds to be extracted efficiently from foodstuffs. For instance,sugars and acids can be extracted from fruit and vegetables,starch from pastry and valuable proteins can be recovered from meat products. The need to recycle non-renewable phosphorus is also a major concern for future food production. Industrial biotechnology can be applied to food waste for the manufacture of valuable fuels, chemicals and materials such as plastics. Utilising science and engineering from the biological world to convert problem materials into something that people need, seen as an opportunity for the UK to generate wealth in an emerging sector called the bio-economy.

Currently food waste is either sent to landfill, converted into lower value products such as electricity and animal feed, or recycled as fertiliser to grow more food. Anaerobic digestion is a rapidly growing market that uses biological processes to convert food waste into a useful bio-based product, energy rich methane gas. Current practices however could be more efficient and a bigger economic win can be achieved. To do this, the best technology fit must come from analysis of the waste composition itself. A sensible product should be targeted to fit the regulatory constraints of the waste feedstock and product market size must correlate with the total waste arising. Some wastes can be very mixed (or heterogeneous) and in this instance it may be a viable option to separate out each competent, with a route to valorisation identified for each. If existing markets are to be accessed however, such as commodity chemicals or fuels, then it may be best to convert mixed materials into a homogeneous chemical intermediate that can drop-in’ to existing supply chains. Sugar is a good example of this, methane gas is another. Once waste is homogenised, the application of a specific technology can be used to create specific product functionality and increasing its selling price significantly. Combination in waste, however, can be a barrier to this and smarter ways of pre-treating waste products are currently being developed in industrial biotechnology circles.

Food waste is either disposed of to landfill or converted to lower value products

Characterisation of waste materials is the key to applying the correct technology for product manufacture. Most food waste contain water and this means pre-drying may be necessary if thermal treatments such as incineration, gasification or pyrolysis are to be used. This can prove to be energy inefficient and very costly, so the application of wet processing technologies is often preferred. Industrial biotechnology fits into this category, where its application can target specific compounds in the waste, either separating them out or converting them into higher value products with increased functionality.

Industrial biotechnology may include fermentation, this is the use of micro-organisms that metabolise the carbon in waste liquids and gases, converting them into fuels, chemicals and materials like plastics. Bio-catalysis this is the use of enzymes to convert starch and carbohydrates into intermediate chemicals such as sugar for use in fermentation or biotransformation, which modifies the chemical structure of a low value compound to form another of much higher value.

At CPI we have developed capabilities in science and engineering to convert biogenic waste materials into value added products. We are currently involved in a number of collaborative research and development projects focusing on areas including: using bio-catalysis to convert waste products from the fisheries industry into a protein rich nutrient feed that has the potential to replace expensive raw materials used in the pharmaceutical industry (BioMega); converting the cellulosic components in municipal solid waste into added value chemicals (Waste2Go — an FP7 project); manufacturing a valuable additive for use in paints by extracting nano-cellulose in root vegetables (Cellucomp); and converting industrial waste glycerol from biodiesel manufacture into algae for the production of road transport fuel (InterSusAl — an FP7 project).

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