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Anaerobic Digestion “Big Opportunity” for Municipal Waste

Urban-based local authorities should consider the anaerobic digestion big opportunity, as an alternative to in-vessel composting for the recycling of municipal biodegradable food waste, according to researchers at WRAP. Speaking today (23 April 2007) at the annual Recycling and Waste Forum in Birmingham on Thursday, WRAP's organics supply programme manager Louise Hollingworth said: “In-vessel composting is obviously very established in the UK but there are only a couple of AD plants in the UK taking biodegradable municipal waste.

Anaerobic digestion plants, like this one run by Greenfinch Ltd in Shropshire, could be the future for municipal waste in the UK according to WRAP:

“There is a big opportunity for the UK to learn from Europe and optimise collection schemes and perhaps for urban authorities as AD solutions are something that could be used”,

she said about the anaerobic digestion big opportunity!.

Ms Hollingworth was discussing a report commissioned by WRAP and published this March, entitled “Dealing with food waste in the UK“.

The year-long study by Dominic Hogg of the consultancy Eunomia focused on the European picture for Anaerobic Digestion – a biological treatment conducted in the absence of air, which produces both a compost product and bio-gas that can generate renewable energy. The study discussed the 124 operational AD plants throughout Europe and the “clear benefits” of the technology.

Ms Hollingworth also said that in the UK many local authorities are:

“concerned about the robustness of AD” and consider it an “unproven technology”.

However she went on to say:

“The European experience flies in the face of this. The anaerobic digestion big opportunity scenario exists. AD has a stronger, overall environmental performance”, than other technologies.

She added, that AD could be seen to be an appropriate technology for urban local authorities as households in urban areas tend to collect a lower proportion of green waste.

Costs WRAP's research also compared the cost of technologies processing biodegradable municipal waste and although AD technology came out as the most expensive, at £45-55 per tonne, in comparison to in-vessel composting at £35-45 per tonne, Ms. Hollingworth said that the possibility of selling the energy extracted from the process had not been included in the predicted costs. More at LetsRecycle here…

Anaerobic Digestion – Big Opportunity Awaiting?

California, USA — While wind and solar generally grab the lion's share of headlines on renewable energy, there are less celebrated, untapped renewable energy resources that can add to the U.S.'s energy mix. One example is a form of waste-to-energy.

The most common waste-to-energy applications in the U.S. include the combustion of municipal solid waste (MSW), landfill gas-to-energy, and the digestion of farm waste or waste water. An often overlooked waste-to-energy resource, however, is mixed organic waste (for example, food and yard waste) anaerobic digestion (AD). AD technologies comes in a variety of shapes and sizes, so for now, we've used assumptions provided by a dry fermentation (that is a digester that accepts higher-solids waste) technology provider.

The U.S. Environmental Protection Agency estimates that in 2008, 250 million tons of municipal solid waste (including organic and non-organic) was generated in the U.S. While 22 million tons of organic waste was diverted for composting, an estimated 43 million tons of organic waste was sent to landfills. The total electric and thermal power (assuming a combined heat and power application) associated with this organic waste is approximately 1 GWe and 1.4 GWth, respectively. The total electric output is equivalent to serving close to 1 million homes.

While composting may appear to be a direct competitor to AD for organic waste, the two are mutually beneficial because remaining digestate from the AD process can be composted and sold. In fact, composting facilities such as Cedar Grove Composting in Everett, Wash., are a primary target for new AD projects.

European companies such as Germany's Viessmann (BIOFerm) and GICON Bioenergie GMBH and Austria's Entec Biogas GMBH have digester technology that is suitable to convert food waste, yard waste and other organic material into energy. Anaerobic digestion was first widely applied in Europe in the 1930 and 1940's and has a history of success due to beneficial waste management practices and energy policies. While the technology is fully commercial, the application in the U.S. has been limited to farm and wastewater treatment plant facilities. Given the greater land availability for landfills, the U.S. has enjoyed cheaper municipal waste disposal than densely populated Europe.

via Anaerobic Digestion: Unaddressed Opportunity – Renewable …

The Food Waste Recycling Opportunity

The disposal of large amounts of food waste has caused significant environmental pollution and financial costs globally. Compared with traditional disposal methods (i.e., landfilling, incineration, and composting), anaerobic digestion (AD) is a promising technology for food waste management, but has not yet been fully applied due to a few technical and social challenges. …

It is envisaged that AD of food waste could be combined with an existing AD facility or be integrated with the production of value-added products to reduce costs and increase revenue. Further understanding of the fundamental biological and physicochemical processes in AD is required to improve the technology. via ADfood wasteChallenges

New Food Waste Recycling Big Opportunity: Cold Anaerobic Digestion

The exciting news in food waste recycling is a new Cold Anaerobic Digestion process that would improve energy efficiency and increase outputs.

Anaerobic digestion involves using microorganisms in oxygen-free environments to break down biodegradable materials (like food waste). The two traditional anaerobic digestive processes (Mesophilic and Thermophilic digestion) generally require temperatures ranging from 20 – 70°C. However, new research shows options for conducting anaerobic digestion at temperatures below 20°C. This reduced temperature requirement would reduce the amount of energy outlets need for processing materials, meaning higher energy payoffs overall. This could be especially impactful for cooler climates interested in using anaerobic digestion as a source of renewable energy.


The study (conduct by researchers from Concordia’s Department of Building, Civil and Environmental Engineering in collaboration with Bio-Terre Systems Inc.) sited negligible tradeoffs for using the cooler digestive process. Also, while certain traditional anaerobic methods only allow food waste to make up a percentage of the waste stream being processed, the new research showed favorable results even when materials were 100% food waste.

Here are some of the additional benefits offered by both the new and traditional anaerobic digestion big opportunity processes:

  • Greenhouse Gas Emission Reduction – Anaerobic digestion is an effective tools for capturing and harnessing methane (a significant greenhouse gas).
  • Renewable Energy Source – Once captured and cleaned, anaerobic digestion processes turn methane into safe, renewable energy.
  • Reduced Water Pollution – Anaerobic digestion serves as a safe method for collecting nitrogen and phosphorus that might otherwise pollute water sources if released in high quantities.
  • Soil Improvement Opportunities – Once nutrients have been collected during anaerobic digestion, they can be dispersed in safe quantities as soil additives and fertilizers to improve crop production and health. … via New Food WasteOpportunity: ColdAD

Anaerobic Digestion as a method for dealing with food waste has rocketed in certain countries, such as Germany, and this trend is set to continue as the rest of Europe works towards the legislation that brings it to the forefront of creative solutions.

There are however other challenges, not least the fact that a considerable amount of the food wasted is actually still in its packaging. Again EU legislation comes into play as it demands specific sell-by dates on food which forces food retailers to dump vast quantities of it on a daily basis. The challenge to the AD sector is in how to effectively depackage the food waste. A priority for the process is to have an homogenous, accessible substrate entering the digesters. This allows effective breakdown and gas production. There is also the issue that the digestate needs to be spread on land after the methane gas is extracted, and clearly it would be unacceptable to have plastic wrapping blowing around the countryside. The anaerobic digestion big opportunity could fail without an answer to this.

BioSep, is a company mainly focused on the front end treatment of food waste and preparing it for AD. Depackaging has been the achilles-heel to the industry, and BioSep aims to match its front end technology – which effectively separates and washes the plastic packaging component as well as removing tins, glass and other non-organic foreign material – with any biogas technology that caters for the back end conversion into energy. via OpportunitiesAD

What Next for The MSW and Food Waste AD Opportunity?

AD remains technically attractive for its ability to process a wide variety of biogenic materials. Billions of tons of readily available feedstock are potentially suitable.

The current economics should not belittle the potential of AD to provide energy and beneficial environmental mitigation of human activities including GHG release and other environmental impact of large scale agriculture and urbanisation

Before getting too excited about what we see as the anaerobic digestion big opportunity. We should recognise that we are not very sophisticated in exploiting AD, as follows:

  • Large gaps in understanding of the biology
  • Very minimal attempts to optimise the bacterial consortia
  • Limited knowledge of interactions with specific substrates
  • Great opportunity for improvement of reactor and system design in particular for high solid content
  • Goals for the anaerobic digestion big opportunity: and Reduction in the cost gas of gas production
  • Expansions of the horizons for AD past energy and waste management
  • Provide research direction to help formulate meaningful policies. via Anaerobic Digestion Industry Overview and Opportunities …

Resolve the worst of these problems and the anaerobic digestion big opportunity, might just-about come-about!

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