Memorandum by the Composting Association
(RC 30)
1. INTRODUCTION
1.1 The Composting Association works on
behalf of over 550 UK members to raise awareness of the benefits
of the recycling of biodegradable resources. It aims to act as
an advocate for the wider composting and biological treatment
industries and to represent their views in a constructive dialogue
with policy makers. The Association envisages an industry in which
best practice is shared, standards are maintained and surpassed
and which makes a positive contribution to safeguarding the environment.
1.2 Food and garden wastes (biowastes) are
thought to comprise in excess of 30% of the municipal waste stream.
As they are biodegradable this represents significant opportunities
for local authorities to collect them separately for composting,
anaerobic digestion (AD) or other biological treatment processes
in order to meet their Landfill Allowance Trading Scheme (LATS)
obligations.
1.3 Currently over three million tonnes
of biowaste are composted every year, producing in excess of a
million tonnes of compost.[37]
These figures are set to rise substantially as local authorities
strive to meet their LATS targets. Estimates of over ten million
tonnes a year of municipal biowaste and five million tonnes of
commercial and industrial waste are diverted from landfill by
2020 may well be conservative.
1.4 This memorandum illustrates the impact
biowaste collection schemes have on the growing biological treatment
industry.
2. BIOWASTE TREATMENT
TRENDS
2.1 Biowaste treatment facilities are well
established in many European countries, and the UK industry is
developing rapidly. The industry employs over 1,200 staff (full
time equivalent), has a collective turnover in excess of £90
million, and has over 300 biowaste treatment sites, handling a
range of feedstocks, principally green and food wastes. The majority
are open-air turned-windrow systems composting green (parks and
garden) wastes.
2.2 Following the epidemic of Foot-and-Mouth
disease in 2001, composting food waste is subject to stringent
legislative controls that require in-vessel composting systems.
These are highly engineered structures operating sophisticated
process controls, designed to ensure optimum composting conditions
and minimum time-temperature profiles are attained. Capital costs
for a 20,000 tonne per annum system are typically in excess of
£ 2 million; an investment that needs to be amortised over
a 10-15 year period.
2.3 Packaging is also beginning to impact
on the biological treatment industry in a number of ways as an
increasing amount of card and paper is being introduced to food
and green waste collection schemes. This is in response to paper
mills becoming more stringent on input quality for recycling,
and shredded paper (for identity fraud protection purposes) generally
not being accepted.
2.4 Significantly, there is a great deal
of interest by retailers in biodegradable or oxo-degradable packaging
for vegetable and fruit produce, ready meals and carrier bags
for example. Some of these polymers compost under typical composting
conditions, whilst other do not; the latter have created considerable
problems at composting facilities as they can contaminate the
end product and affect moving machinery. There is currently much
confusion in the marketplace amongst retailers and the general
public about the performance of these polymers.
2.5 Notwithstanding, compostable bags can
greatly assist in the separate collection of food wastes. They
enable hygienic conditions to be maintained, helping to instil
confidence and acceptability by the public.
2.6 There is currently considerable interest
in anaerobic digestion. This degrades biowastes in the absence
of oxygen resulting in biogas that can be used as a fuel for electricity
and/or heat generation, and digestate that may either be applied
to land directly, or, in most cases, post-composted. AD is particularly
suited to food wastes, but does not degrade woody wastes. There
are currently only a handful of sites in the UK.
2.7 It seems likely that existing composting
sites will begin to diversify and become integrated biowaste management
sites, operating in-vessel, open windrow and AD processes. There
is even scope for biomass boilers to burn oversized woody wastes.
2.8 The development of these integrated
sites will provide a flexible solution for local authorities,
commercial and industrial waste producers. A diversity of processing
options can allow a cost-effective mix to be established, thereby
reducing the likelihood of assets becoming stranded and reducing
business risk.
2.9 The ways in which biowastes are collected
has a marked influence on processing infrastructure and the end
uses to which the treated materials can be used. The key issues
that affect Composting Association members are discussed below.
3. IMPACT ON
COMPOST QUALITY
3.1 A great deal of work has been carried
out on developing compost markets in recent years. The Composting
Association was instrumental in developing the UK's first standards
for compost, which, in conjunction with the Waste and Resources
Action Programme (WRAP) has been translated into the BSI Publicly
Available Specification 100 (PAS 100) for Composted Materials.
This has set the basis for the publication of the Quality Protocol
for Compost,[38]
published in March of this year that sets criteria to establish
when composted materials have been processed sufficiently such
that they have been fully recovered and no longer classed as a
waste.
3.2 Sustainable market development necessarily
relies on materials that are fit-for-purpose and consistently
meet minimum quality specifications. The quality of the input
feedstocks is the key variable that affects the quality of the
output material. In order to meet the PAS 100 standard and the
criteria in the Quality Protocol, biowastes need to be delivered
to a site from separately collected sources with minimal contaminants.
3.3 In practice, this means that feedstocks
need to be collected separately and delivered to a site for processing
shortly after their generation. Many local authorities operate
effective separate collection schemes, either through their household
waste recycling centres or through kerbside schemes.
3.4 Collection schemes do however need to
deliver defined waste types with minimal contaminants. These need
to be designed appropriately and communicated effectively, on
an on-going basis, to the public.
3.5 While treating mixed municipal wastes
in a mechanical biological treatment (MBT) facility will result
in a Compost Like Output (CLO) that may have beneficial use when
applied to some soils, given the potential for contamination this
material seems likely to remain classed as a waste and hence used
in a regulated manner. Similarly, it may currently not be used
on agricultural land where food and fodder crops are grown, thus
reducing the potential benefit of organic matter application to
agricultural soils.
4. IMPACT ON
EMISSIONS
4.1 Problems can arise at composting facilities
when odorous feedstocks are delivered, which cause handling and
processing difficulties. This principally occurs during late spring
and early summer when biowastes have been stored in warm weather
for a period of time before delivery. In some cases odorous loads
have been rejected at site and sent to disposal in landfill, or
the compost operator has received complaints and enforcement notices
by the Environment Agency: clearly neither situation is desirable.
4.2 In order to prevent such problems occurring
collection contracts need to retain some flexibility to ensure
biowastes are delivered to site promptly after collection, especially
during peak periods.
5. CAPITAL EXPENDITURE
AND INFRASTRUCTURE
5.1 The quantities and composition of green
wastes necessarily varies throughout the year, which can create
operational challenges for site operators. Most open-air windrow
systems can accommodate seasonal fluctuations through changing
the size and shape of the composting heaps, as well as the ways
in which they are aerated.
5.2 All food wastes that emanate from a
kitchen need to be composted in an in-vessel system and approved
by Animal Health in order to meet with the Animal By-Products
Regulations (2003). Systems that co-collect green wastes and food
wastes need to be treated in-vessel, which can increase processing
costs. Significantly, the composition of the feedstocks will vary
throughout the year, which can be problematic, as volumes at certain
times of the year may be sub-optimal.
5.3 Collecting food and green wastes separately
will generally provide site operators with greater flexibility
to size in-vessel systems appropriately and to blend the mixes
for optimal degradation, for example with green wastes or cardboard.
This would be beneficial to both the local authority financially,
as well as the operator. Separately collected food wastes could
also be digested anaerobically (in an AD plant), which would also
have the added benefit of generating renewable energy.
5.4 Due to the high CAPEX of in-vessel composting
and AD facilities, investments will however need to be realised
over a 10 year period which must be considered when local authorities
are negotiating contracts.
6. INTEGRATING
COMMERCIAL AND
INDUSTRIAL WASTE
COLLECTIONS
6.1 Most biowaste facilities have been established
on the basis of local authority contracts for municipal wastes.
However, significant synergies exist to treat commercial and industrial
wastes at these and upcoming sites.
6.2 Industrial wastes may potentially provide
clean, consistent feedstocks which could be blended with separately
collected municipal biowastes. There would be obvious commercial
advantages to the site operator in choosing this approach.
6.3 As the landfill tax is set to rise,
producers of commercial biowastes (eg restaurants and catering
outlets) in particular could usefully integrate with municipal
food waste collections. This could have the added benefit of reducing
transport distances to sites as economies of scale are realised.
7. CONCLUSIONS
7.1 Biowaste collection contracts between
local authorities and the private sector need to be configured
in order that:
— Quality biowastes are collected separately
from other wastes so that they can be transformed into quality
composts
— Collection frequencies can be varied
as appropriate to accommodate seasonal increases in waste arisings
in order to prevent wastes turning odorous before delivery to
site
— Contracts are of an appropriate duration
to enable the private sector to invest in highly engineered in-vessel
composting and anaerobic digestion facilities.
7.2 Local authorities should consider collecting
food and green wastes separately, to enable site operators a greater
degree of flexibility with processing than the current co-mingled
collections processing system allows.
7.3 There is considerable interest in biodegradable
packaging by retailers. In order to ensure that these materials
are compostable and will not adversely affect the composting process,
all compostable polymers should be independently certified to
the European Standard EN 13432:2000.
7.4 Potential synergies exist between commercial
and municipal waste collections and the Association would suggest
that local authorities should be incentivised to co-collect biowastes
where appropriate.
7.5 Successful collection schemes rely on
targeted and ongoing communication campaigns. WRAP should build
on its existing Recycle Now programme to assist local authorities
to communicate information about separate biowaste collection
schemes.
7.6 Further technical work needs to be undertaken
to assess the quality and potential end uses of Compost Like Outputs
from MBT facilities that will treat mixed (unsorted) residual
waste.
37 Market survey of the UK composting industry 2005-06
(DRAFT) WRAP and The Composting Association. Back
38
The Quality Protocol for the Production and Use of Quality Compost
from Source-Segregated Biodegradable Waste (2007) WRAP and the
Environment Agency. Back
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