Modern alchemy: profiting from food waste
Investing in more effective waste management can be a rewarding experience for food companies, with a recent report from Champions 12.3 – an international coalition dedicated to meeting the United Nations’ sustainability target of halving food waste by 2030 – suggesting that companies typically save £14 for every £1 invested in reducing food waste.
“A third of the world’s food is wasted – and yet almost a billion people go to bed hungry each night. That simply cannot be right. But even if the moral imperative doesn’t move us, the clear business case should swing people to act,” says Dave Lewis, group chief executive of Tesco and chair of Champions 12.3.
Using anaerobic digestion (AD) to turn food waste into methane/energy and fertiliser is well established in the UK. Now, some of the effort is turning towards making it easier – and more cost-efficient – to connect producers of waste with their local AD facilities in order to soak up spare processing capacity.
“The big issue is there’s huge amounts of excess capacity. The government created subsidies to entice people to build food waste AD systems a few years ago and now – a very rough number – there’s probably 5Mt of capacity to take food waste and there’s currently only about 2.5Mt of food waste going into these plants,” says William Heller, chief executive of Organic Waste Logistics (OWL), which offers an approach designed to ‘join the dots’ and increase the supply of good quality feedstock for AD plants.
OWL’s solution is based on BioWhale, which is essentially a macerator and vacuum tank combination built into a standard shipping container.
Savings and reducing carbon footprint (back to top)
“You throw any unavoidable waste into a hopper and it’s sucked into a macerator and ground to around 8mm to form a biosoup. It’s slowly mixed in the tank so it starts to hydrolyse,” says Heller. He adds that this mess- and odour-free approach contrasts with the use of skips and wheelie bins.
Once the tank is full, OWL sends a tanker to empty it and transport the resulting soup to the nearest AD plant. “You might be looking at calling the tanker 18 times a year compared with 250 truck journeys,” says Heller. “So it saves money and reduces the carbon footprint.”
In a recent project, OWL installed a 24t BioWhale unit for Cargill Meats Europe in Wolverhampton. The site had previously stowed waste from chicken products in skips, which had to be housed in a refrigerated storage area and removed daily.
The BioWhale frees up the refrigerated storage for high-value products, prevents spills and odours and massively reduces the pick-up frequency.
Cargill Meats Europe’s plant operations manager Dave Mackay says: “OWL’s system makes us more efficient and sustainable, in one simple and elegant package. We have minimised our environmental impact and captured the full commercial value of our waste.”
Emerging technologies (back to top)
Conventional AD is great as far as it goes, but might we be about to witness the emergence of a new wave of technologies that go much further by transforming food waste into high-value chemical feedstocks?
It’s an approach known as valorisation and some observers think it could be coming to a waste stream near you in the near future.
“Valorisation is upcycling of waste, rather than downcycling,” explains Gavin Milligan, who is sustainability director for William Jackson Food Group and a member of the management committee for the Biotechnology and Biological Sciences Research Council (BBSRC)-funded Food Waste Network of academic and industrial partners.
“It’s about finding a means of extracting specific materials that have an inherent value that’s significantly greater than the waste or its embedded energy,” says Milligan.
Food Waste Network is one of 13 networks funded by the BBSRC to focus on novel biotechnology processes.
“There are other mechanical or physical processing methods but this is specifically about biotechnology,” says Milligan. “It can include AD. Using AD to produce methane is not that interesting, but AD doesn’t have to go on to methanogenic stage necessarily – you can stop it before it gets there and generate short chain fatty acids or alcohols, esters or other simple molecules that can be used in the chemical industry.”
Physical processing has been around for a long time, such as extracting oil of cloves or orange oil by steam distillation, he explains: “But our work is about trying to find low-energy [biotech-based] ways of doing it, using millions of years of evolution potentially to do the hard work for us, rather than using the ‘sledgehammer to crack a nut’ of putting in loads of energy to heat something up.
“There are established organisations that are already taking these things through to pilot scale, so I would say that it’s imminent really that we will see occasional applications.”
Environmental sustainability (back to top)
Professor John Clark heads up the Green Chemistry Centre of Excellence at the University of York. He agrees that the critical thing with valorisation is to develop processes that are themselves environmentally sustainable: “If you take the example of pectin, it’s already being extracted from apples and citrus as the commercial source, but the technology being used at the moment to do this isn’t very green. In some cases it’s quite hazardous … We could be doing it much cleaner and greener and, therefore, with much wider applicability.”
He also says that a two-step approach may be needed to valorise mixed food waste, rather than trying to use it directly as a source of high-value products.
“Direct extraction from a complex waste stream is going to be problematic,” says Clark. “The mixed stream almost by definition is going to be variable, but all mixed streams will contain certain materials. So, if you extract those and then use them to make chemicals, that’s absolutely sound …
“There are many other things that can be made from ‘resource-agnostic’ stuff. So anything ‘cellulosy’, which is any kind of peel or shell or stone, can be turned into a whole range of interesting materials.”
Bacteria clear the way to lower Mogden charges
For many British food companies, transforming unavoidable waste into a lucrative revenue stream remains a distant dream. Instead, they are looking more immediately for ways to minimise how much it costs them to dispose of their waste.
In the case of waste water, water companies calculate disposal charges using the Mogden Formula, which factors in volumes and levels of contamination. NCH Europe’s Waste Water Innovation Platform has developed a system to help minimise such charges.
BioAmp consists of two parts. The first is a range of automated, computer controlled delivery systems and the second is FreeFlow, a biological agent available in either tablet or liquid form, which contains up to 12 species of bacteria to break down complex waste streams.
The system automatically doses the correct quantities of live bacteria into a plant’s water system every 24 hours to provide continuous treatment.
FreeFlow 50 is a dosing mechanism for the liquid, which is a biological solution containing 10 strains of food-safe bacillus bacteria that clear organic waste, says NCH.
FreeFlow 100 is a premium system that is much stronger. It contains liquid nutrient and biological systems to boost the performance of the bacteria.
“The NCH Europe bacteria are active from the moment they enter the system, meaning that they are instantly effective and perfect for times of high demand,” says Steve Martin, projects director of the wastewater and biologicals platform at NCH Europe. This contrasts with products that contain dormant bacteria, which can take several hours to become active.
“When dispensed, the FreeFlow Liquid’s live, active bacteria solution begins to feed and digest the FOG [fats, oils and grease] and organic waste.
“This FreeFlow system is much quicker than traditional methods and enzyme-based products, which have often already passed through the built-up area of grease, fats and oils before starting to take effect,” he says.
“With many alternative products taking three to four hours, or even longer, to become active in the system, FreeFlow Liquid reduces the need for lengthy retention plans. FreeFlow Liquid also works across a much larger range of pH, temperature and oxygen conditions.”
Improving the condition of public drains and sewers with better waste water treatment is to everyone’s advantage, says Martin.
After all, Water UK says that water and sewerage companies in the UK respond to approximately 366,000 sewer blockages every year and that impacts on everybody.
“A West Midlands restaurant was fined more than £5,000 in 2016 because it had continuously poured liquid fat down the drain that solidified in the sewer system and caused a blockage in the drainage systems,” he says.
“Whereas in London, a FOG accumulation the size of a school bus was found in the water system, taking more than a month to remove.”
