Category Archives: Anaerobic Digestion Facility

Albion’s ABC of Waste Management – O – Open Windrow Composting

Organic waste can be treated through physical, chemical, or biological forms of waste management. The fundamental aim of organic treatment is to degrade the easily available compounds; stabilise the material; and reduce its volume. Biological treatment includes composting, which has multiple benefits, including:

  • Employment opportunities
  • Reduction of waste to landfill/incineration, which helps control greenhouse gas emissions
  • Recovery of useful organic matter for use as soil amendment, assisting with soil quality improvement (increasingly important due to intensive cultivation and climate change)
  • Stabilisation of waste in order to remove pathogens

Commercial-scale composting is available in two forms – open air windrows (organic materials are placed in long heaps) or in-vessel systems (material is enclosed). In-vessel composting is often used to handle food wastes and animal by-products, as this option isolates the waste from the environment, and people. This is important as these wastes have a higher risk of containing pathogens, compared to garden wastes.

Garden wastes contain items such as twigs, leaves, grass clippings, and also larger items like tree stumps, which are broken down prior to the composting treatment through shredding. These materials are often collected via garden waste kerbside collections or recycling centres, and they are an ideal feedstock material for open-air windrow composting.

PAS100 (Publicly Available Specification for Composted Materials) is a recognised set of standards laid out as guidance for organics recycling. The standards specify that compost reaches a minimum of 60˚C for at least 7 days, to inactivate any pathogens that may be present within the waste. Once composting is complete, the product is graded and sold. This allows any contaminants or materials not quite broken down to be removed. The compost sold can be used as agricultural soil conditioners, or for gardening purposes, or may even be used on golf courses.

However, there can be some issues with composting – for example, concerns over heavy metal pollution of agricultural soils due to composts containing contaminants such as metals and plastic, which may then have a pathway to enter the food chain. Composting sites may also create issues with odours, noise, vermin, VOCs, and bioaerosols – the latter of which arises due to micro-organisms within the waste.

Composting encourages micro-organisms to grow, as these are crucial to actually break the waste down. For composting to be efficient, the material needs to be well-aerated, so these micro-organisms have access to oxygen. Open windrows are aerated by regularly turning material. Additionally, compost is often screened (sieved) to produce the end-product – a quality soil supplement. These processes, along with shredding of large items within incoming waste, all involve handling the compost and moving the material, which can generate dust, and create bioaerosols.

Bioaerosols have the potential to present environmental issues and occupational hazards at any waste treatment facility, if it handles large quantities of organic material. A number of serious health effects, including respiratory and gastrointestinal illnesses, have been linked to high bioaerosol concentrations. As such, composting sites may be required to conduct bioaerosol monitoring, in order to manage the risk of bioaerosols.

In Scotland, composting sites must have a Waste Management Licence (or they will require an exemption). SEPA licences composting sites, and when doing so, they must consider the issue of bioaerosols. In England, sites carry out monitoring according to standards from The Environment Agency. A site’s operations and the amount and type of waste it handles, its possible high-risk areas, and the guidance provided by the relevant environmental authority, are all things that a site may factor in when considering which type of bioaerosol monitoring they want to conduct.

Albion can supply consultants with the knowledge and expertise necessary for conducting a range of bioaerosol assessments, including:

  • Occupational bioaerosol monitoring – assesses exposure for site staff
  • Environmental monitoring – determines possible exposure levels at residencies or workplaces near the site
  • Site-specific bioaerosol risk assessments

By analysing the risks associated with bioaerosols at a certain site, and who may be affected by them, we can then also provide guidance on how to manage and lower a site’s bioaerosol emissions. Albion Environmental has a number of environmental monitoring specialists, trained to complete a wide range of services within the field of environmental monitoring, including those related to bioaerosols. Find out more about the environmental work we do here.


Albion team attended The REA Organics Scotland Conference, organised by The Renewable Energy Association and hosted in Aberdeen. This conference allows groups within the organics sector – including local authorities, waste operators, waste management companies, and industry consultants – to come together to discuss the issues facing the Organic Waste Treatment sector. It is the ideal platform to look at innovative developments, current opportunities, and certain challenges and difficulties within the field.

The event started with a visit to an Anaerobic Digestion (AD) site being constructed near Aberdeen’s TECA (The Event Complex Arena). It was fascinating to see the plans for the site, how it would work, and to see the inside of an Anaerobic Digestion tank. Once the AD site is operating, it will produce enough electricity to power TECA. The plant will use 81,000 tonnes of feedstock each year, and this will include Aberdeen’s food waste, along with agricultural wastes and crop fuels.

In Scotland, building more organic waste treatment plants could be crucial in meeting the target to ban any biodegradable municipal waste from entering landfills from 2025 onwards (extended from 2021). This is just one of many important policy targets implement by the Scottish Government, to improve waste management. Another aim in Scotland is to cut food waste by 33% (from the 2013 figure) by 2025.

The first conference speaker covered this topic, by introducing the Scottish Governments Food Waste Reduction Action Plan & explaining the different methods that will be used to minimise food waste. Most of the other speakers, focused on organic waste management. Over the course of the conference, there were multiple interesting talks on a variety of topics, including:

  • Plastics found in organic waste, and what can be done about this
  • Summary of a study tour that explored the methods that Italy use to handle organic wastes
  • The process of building an organic waste treatment plant
  • How Aberdeen is using renewable energy to transform the city
  • Improving the quality of compost outputs from composting sites
  • Panel discussion on promoting the benefits of recycling organic materials

Albion’s very own KTP (Knowledge Transfer Partnership) Associate presented at the conference too. She gave a well-received and engaging talk about bioaerosol monitoring and the benefits of a KTP. The talk included a description of what bioaerosols are,why it is important to monitor them and ways for sites to manage and minimise the risk of bioaerosols.

Bioaerosols are often generated by microorganisms, and high levels of microorganisms are crucial in the process of degrading (and therefore treating) organic wastes. As such, organic waste treatment can be strongly linked to high concentrations of bioaerosols – which can have certain negative health effects for humans. This makes bioaerosol monitoring an important subject.

Going forward a mutual understanding of both the key issues facing organics recyclers and how environmental and health & safety legislation may fit will help progress this KTP. Following on from the KTP, our environmental consultants here at Albion Environmental will have acquired the expertise and in-depth knowledge needed to provide a wide array of bioaerosol services that are useful to any potential clientstargeted specifically at their needs.

Information about the services our environmental consultants can provide can be found here

Could France’s Supermarket Waste Law Work in Scotland?

Nearly two years ago a law was introduced in France in which supermarkets were prohibited from destroying any unsold, edible food products.  The law obliges the retailers to sign contracts with charities agreeing terms for regular donation of the unsold produce. Penalties of up to 75,000 Euros and even facing up to two years in prison ensured supermarkets were quick to put deals in place with charities, however would this be an effective way of dealing with food waste in Scotland?

Under existing regulations supermarkets have to ensure their food is either composted (with compost being produced) or an Anaerobic Digestion (AD) process (produces digestate (a liquid land fertilizer) and energy in the form of methane gas). So at moment it is not ideal that food is being wasted but, due to the cost of treatment, there is a financial incentive for supermarkets to try and minimise the food waste generated. If they are simply allowed to give the waste away for free is that not simply shifting the responsibility away from them and onto the charities, which will then have excess material and will end up having to pay the disposal costs? This therefore raises questions whether charities would have the infrastructure and be equipped for the storage and distribution of this amount of food, or whether it would become a burden for these organisations?

Yes charities can make good use of the “free” food, but will they not just end up being a free disposal outlet for supermarkets?


Albion’s ABC’s of Waste Management – A

 A – Anaerobic Digestion (AD)

Anaerobic digestion (AD) is a natural process where in the absence of oxygen, micro-organisms/methanogens break down organic, biodegradable matter to create biogas and nutrient rich fertiliser. The process is used to treat organic waste such as food waste, waste water and animal manure. The biogas that is harvested can be used to produce heat and electricity or alternatively it can be treated to create biomethane which can be fed direct to the national grid. There are two methods of anaerobic digestion, mesophilic which operates around 35-40 degrees centigrade and thermophilic which can reach up to 60 degrees centigrade and the method used is determined by the feedstock that is to be processed. A AD Plant Albion Environmental have assisted anaerobic digestion plants to ensure that if they accept animal by-products (ABPs) and / or catering waste, that they are compliant with the Animal by Product regulations ensuring that the end products are safe. For further information on Anaerobic Digestion please visit ‘Anaerobic Digestion and Biosources Association or the Biogass Association

SEPA Consultation – Food Waste Management in Scotland

Consultation on proposed new guidance on Food Waste Management in Scotland and review of SEPA’s end-of-waste regulatory positions for compost and anaerobic digestate.

The 18th of May 2016 saw SEPA launch the consultation on guidance which sets out obligations along the chain of food waste management in order to achieve high quality recycling.  This chain of management includes the waste producer, collection service provider, food waste treatment facility and final user of the food waste derived compost and / or anaerobic digestate.

New waste regulation across Scotland over recent years has led to a significant change in the manner in which waste must be presented for collection and treatment. Stricter targets for food waste recycling have given rise to the opportunity to change the manner in which industry deals with food waste, and how the products of this process can be used.

Albion Environmental Ltd is delighted to be a consultee and encourages all interested parties to offer feedback.

Responses are being sought from all  interested parties including food waste producers, collection service providers, food waste treatment facilities and farmers, contractors or land managers involved in the application of food waste derived anaerobic digestate or compost to agricultural land to provide feedback.

Further details and a link to the consultation document can be found here.

Albion Environmental Ltd can provide a full range of support and assistance to your business, if you wish to discuss how the consultation can affect you, or any other support needs please contact us on  01292 610428 or