Category Archives: Composting

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’s ABC of Waste Management – K KERBSIDE COLLECTION

Are You Helping or Hindering Scotland’s Recycling? How can this be improved?

  • Currently the contamination rate in the Household waste recycling streams ranges from 0.91% to 43.04%*
  • The average contamination rate for Scotland’s recycling is 17%

*These figures, provided by SEPA, do not include waste that was so badly contaminated it does not make it to the recycling facility and instead is sent to energy from waste facilities or landfill.

Contamination in the recyclate waste streams is currently plaguing Scotland’s recycling efforts.  Plastic is the main problem with people finding it difficult to determine which plastics are recyclable due to the range of plastic polymers and differences between recycling schemes. The BBC have estimated that incorrect recycling/disposal of plastics alone costs Scottish councils about eleven million pounds per year.

Kerbside collection of recyclable material generates income for local authorities. The better quality produced; the higher price councils will receive. If household residents do not separate the recyclable materials, or put the wrong items in the recycling bin, then the whole vehicle load of recycling may be contaminated and sent to landfill or incineration. As a result, the council will not receive revenue for the material and they will also pay the landfill cost.

Is Scotland Reaching its Domestic Recycling Targets?

  • Currently only 44% of domestic waste is put in the recycling bins
  • Scotland is working towards a 70% recycling target by 2025

It is clear that Scotland needs to increase both the quality and quantity of its domestic recyclate. How can this gap be narrowed? Education in the benefits of improving the quality of recycling is required across all councils. A poll conducted by Viridor in Scotland found; 77% of people would recycle more if they could see how the money saved was being invested in public services at a local level. The pending Scottish landfill ban will only increase the importance of achieving this target. When the Scottish landfill ban is implemented in 2025 it will be in councils’ best interest to do everything in their power to increase the recycling rate of their residents in order to keep residual disposal cost to a minimum.

How the Recycling System Should Work.

Most councils recognise the following materials as recyclates and will offer a collection service for; Glass, Plastic, Metal, Paper and Card, Garden Waste and Food Waste. In an attempt to improve recyclate quality and quantity councils are moving away from comingled recycling, thus simplifying the sorting process. The recyclate is collected, separated on a picking line and then bulked to be transported to the end buyer.

*Scottish Environment Protection (SEPA)

Why Should You Recycle?

Financial Benefits– Councils use profits generated to subsidise their costs which can reduce any potential increases in council tax for residents.

Environmental Benefits– Recycling reduces pollution caused from collecting new materials while conserving natural resources.

Social Benefits– Some councils give a percentage of recycling profits as charitable donations and others use savings generated to subsides other local programmes and projects.

What Can Albion Do?

  • Albion can provide councils with a range of services to help improve councils waste management services.
  • We can work with councils to develop waste management strategies to reform waste collection services with the aim of increasing recycling rates while reducing long term operating costs.
  • We can undertake waste analysis via sampling which identifies council’s current contamination rates of both their residual and recyclates, and provides vital information to aid decision making. The results of this analysis can be used to identify areas where improvements can be made.

To find out more or to have an informal chat please contact Jane Bond on 01292 610428.

Waste Compositional Analysis – Perth & Kinross Council

Albion Environmental provide specialist Waste Compositional Analysis to Councils in order to assist them with developments of their waste strategies.

As part of the development of Perth and Kinross Council Waste Strategy, and to help influence their recycling, Perth and Kinross Council have produced a short public information video to explain the key findings of the residual waste in Perth & Kinross. Albion Environmental were the contractor carrying out Waste Compositional Analysis of the general waste on three different occasions from 2018 to 2019, to provide the data during the development of their campaign.

Albion staff Les Thomson and Chris Eccles star in the later stages of this video. Hard and dirty work but essential to provide councils with the vital information they need to develop their strategies. Well done Les and Chris!!

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?

supermarket-waste

Albion’s ABC’s of Waste Management – O

O      Open Air Windrow Composting

Open Air Windrow Composting (OAW) is a process used primarily for organic matter such as garden or animal waste. These materials are piled in long rows in which naturally occurring microbes feed on to break down and turn into compost.

Organic materials gathered from multiple sources including Council’s seasonal garden waste kerbside collections or recycling centres are used in this process however food waste is not suitable as it requires another process in which it is enclosed rather than in open air. However, the garden waste can contain such items as twigs, leaves grass clippings and prunings while larger items such as tree stumps and branches are too bulky to broken down by the Open Air process and require shredding prior.

After the materials are placed in their large, long rows the natural bacteria gets to works breaking the organic matter. This process can generate a lot of heat and even give off steam, with it being note that the inside of a windrow can reach temperatures of up to 55°C. Throughout the process the rows are turned and it can take typically 12 to 16 weeks to complete.

Once completed the product is graded and sold. This allows any contaminants or materials not quite broken down to be removed. The compost sold may be put to multiple uses as agricultural soil conditioners or it could even be used on golf courses.