BioCycle June 2005, Vol. 46, No. 6, p. 59
Latest report from the UK Composting Association highlights a 20 percent increase in feedstocks composted to almost two million metric tons.

SINCE 1994, The Composting Association of the United Kingdom has conducted surveys to evaluate developments in the composting industry, providing detailed information on trends, growth and policy developments. The just-published State of Composting in the UK, 2003/2004 continues its impressive observations, highlighting that between 2001/2 and 2003/4 the amount of material composted in the UK increased by 20 percent to 1.97 million metric tons.
According to Tony Breton, Communications Manager of The Composting Association, “the report shows how the composting industry is continuing to expand while demonstrating professionalism and the ability to adapt to the changing regulatory framework. It also shows a considerable growth in small, dispersed facilities, which are beneficial as they enable treatment of waste near to where it is produced.”
Prepared and written by Rachel Slater of The Open University, Peter Davies and E. Jane Gilbert of The Composting Association, the publication has a most important role in assessing the impact of composting on many policy developments aimed at managing biodegradable wastes more sustainably. The Waste And Emissions Trading (WET) Act 2003 and the Landfill Allowance Trading Scheme (LATS) introduce progressively tighter restrictions on the amount of biodegradable wastes that authorities can landfill, designed to meet the Landfill Directive targets. In addition, varying recycling and composting targets are set out in the respective Waste Strategies for England, Northern Ireland, Scotland and Wales, and the Household Waste Recycling Act 2003 has come into force in England.
This survey was carried out in 2004, and covered the financial year April, 2003 to March, 2004. Data were collected from compost producers and local authorities by means of either a postal or electronic questionnaire. The questionnaire sent to local authorities covered organic waste collected from household waste recycling centers and curbside recycling programs. The questionnaire sent to compost producers sought data on organic waste types and quantities, facility and process types, together with product and market information. The survey was distributed to a total of 474 local authorities and 410 compost producers and attained an overall response rate of 43 percent.
Responses obtained suggest that the industry has continued to show sustained growth. Since the previous survey for 2001/02, the total number of sites has increased by 49 percent from 218 to 325 in 2003/04, and the total quantity of wastes composted has increased by just under 20 percent, from 1.66 million tonnes (mt) to 1.97 mt in 2003/04, a growth of 0.31 mt. This equates to an average annual growth rate in the number of sites of 22 percent, and an average annual growth rate in throughput of 10 percent.
Compared with previous years, the growth rate in number of sites has increased while the growth rate in throughput has decreased. This is explained by the development of on-farm composting through a relatively large increase in small-scale on-farm sites compared with centralized sites. The number of on-farm composting sites recorded more than doubled, while the number of centralized sites increased by 5 percent. As a proportion of the total, wastes composted at centralized sites fell from 92 percent in 2001/02 to 87 percent in 2003/04, the result of the greater rate of growth in on-farm composting (up from 8 to13 percent). Wastes composted at on-farm sites roughly doubled from 0.13 mt to 0.25 mt. Analysis of the 0.31 mt increase in additional wastes composted since 2001/02 survey shows that the expansion of existing sites accounted for around 50 percent of additional processing capacity, while new on-farm sites accounted for around 35 percent, with new centralized sites contributing the remainder.
DEDICATED COMPOSTERS AND WASTE MANAGEMENT COMPANIES
The UK composting industry was dominated by two main types of operator: “dedicated compost producers” (organizations whose primary activity is compost production), and “waste management companies” (organizations involved in a range of waste management activities that also operate composting sites). Collectively these two types of operator processed 95 percent of wastes composted at centralized sites. Agricultural organizations (individuals or organizations involved in farming, or linked to agricultural activity) processed 85 percent of wastes composted at on-farm sites. The pattern of centralized site ownership was relatively constant with previous years. Most dedicated compost producers operated a single larger-scale site (with typical annual throughput of between 5,000-10,000 tonnes). In contrast, waste management companies tended to operate multiple, smaller-scale sites (typical annual throughput of between 2,000-5,000 tonnes). Most agricultural organizations operated small-scale on-farm sites (typical annual throughput of < 1,000 tonnes) and tended to be single site operators, or one operator coordinating activity at multiple sites (typically more than six sites). while the growth in the on-farm sector is an important development for the industry, the proliferation of small centralized and on-farm sites needs to be complemented with the development of larger-scale sites if the industry is to provide processing capacity that will significantly contribute to the Landfill Directive targets.
Although there were large geographical variations in the quantity of wastes composted in the UK, these were relative to the population on a per capita basis, with quantities composted per household similar across England, Northern Ireland, Scotland and Wales (giving national figures ranging from 71-80 kg per household per annum). As would be expected, the largest increase in wastes composted was observed in England. However, the larger rate of growth was observed in Scotland and Wales. Organic wastes processed in Scotland tripled, and in Wales it more than doubled. As in previous surveys, the data showed that Wales and Scotland processed a greater proportion at on-farm sites compared to England, although in Scotland this proportion remained relatively static since the last survey, while in Wales the proportion of wastes composted on-farm increased. The report showed that a divide still existed between the North and the South of England, with approximately one-third more material per household being composted in the South.
HOUSEHOLD AND GREEN FEEDSTOCKS
The compost producers were asked to provide information on the source of wastes they composted, which included household wastes collected from Household Waste Recycling Centers (HWRC) and the curbside. Data supplied by compost producers tallied well with local authority data on wastes they collected for composting from HWRC and curbside programs. According to compost producers, 1.44 mt of household wastes were composted in the UK in 2003/04, and according to local authorities, 1.36 mt of household wastes were collected for composting. As in previous years, HWRC continued to be the main collection method, accounting for around three quarters of household waste composted. However, the dynamics between HWRC and curbside collection options are beginning to change. The quantity collected from HWRC remained similar to that reported in 2001/02, whereas the quantity of green waste collected from the curbside had more than doubled. In 2001/02 curbside collection accounted for around 14 percent of household wastes composted. By 2003/04, this had increased to 29 percent. Growth in curbside collections of green waste by the programs recorded in this survey is expected to continue, as over half of programs had been in operation for only part of the survey period.
Of the 1.97 mt of wastes composted, 73 percent was household waste, 4 percent municipal nonhousehold waste and 23 percent commercial wastes. To date the industry has been able to sustain growth with a reliance on green waste, which accounted for 95 percent of municipal wastes composted, and virtually all household wastes composted. Despite considerable and sustained growth, only approximately one-fifth of the estimated 7 mt of household garden waste arisings in the UK in 2003/04 were composted by the industry, while the estimated 6 mt of kitchen wastes remained a largely untapped resource.
Given that the industry continued to rely on green wastes for composting, it follows that open-air mechanically turned windrows remained the most common processing technology used at both centralized and on-farm sites. This relatively low technology method was used at 278 of the 325 sites reported in the survey, accounting for 82 percent of wastes composted in 2003/04 (81 percent of wastes composted at centralized sites, and 89 percent of wastes composted at on-farm sites). As pressure increases to divert both green waste and food waste from landfill, suitable processing technologies capable of handling food waste will be required (such as in-vessel composting systems). There is some evidence to show that is starting to develop, for example the number of sites employing in-vessel technologies increased from 12 in 2001/02 to 18 in 2003/04. This survey coincided with the introduction of The Animal By-Products Regulations 2003, and in the first year of regulation 14 facilities were undergoing validation for the processing of catering (food) wastes by the State Veterinary Service.
Although this expansion into food waste composting is positive, it is still at a very early stage of development, and rapid expansion of food waste composting capacity will be required to contribute to the required landfill diversion targets. This rapid expansion requirement is set against the tension of often lengthy planning permission and waste management license approval processes. Developing food waste composting capacity also requires appropriate curbside collection systems. In 2003/04, most curbside collection programs were “green waste only”, with only a tiny fraction of programs collecting food waste. The characteristics of food wastes differ from green wastes in that they have a greater density and degrade more readily. This has implications for curbside collection systems, and systems designed to collect garden wastes are unlikely to be most efficient for collecting food wastes.
SITES AND STANDARDS
There were 83 sites recorded in the survey whose products complied with at least one independently certified composting standard. The two most common standards were the British Standards Institution (2002) Publicly Available Specification for Composted Materials (PAS100) and The Soil Association Standards for Organic Food and Farming. Overall, sites that complied with at least one independently certified standard accounted for 45 percent of all wastes composted.
The survey reported 1.2 mt of compost product produced, of which, the largest fraction was soil conditioner (61 percent), followed by mulches (16 percent). Other fractions including growing media constituent and ingredients in manufactured topsoil, while turf dressings accounted for the remainder (23 percent). This breakdown of product types was similar to that observed in 2001/02. The majority of compost product was used on-site, which increased from 39 percent in 2001/02 to 50 percent in 2003/04. The proportion of product sold fell from 47 percent in 2001/02 to 40 percent in 2003/04 (although actual quantity sold increased from 0.45 mt to 0.48 mt) and the proportion distributed without charge fell from 14 percent to 10 percent. Composted product used “on-site” mainly referred to use on-farms or for landfill engineering (including landfill cover). The use of material in landfill engineering fell by 18 percent between 2001/02 and 2003/04, and hence most of the growth in on-site use resulted from composting on farms.
Compost products were distributed to several markets. Agriculture was both the largest and the fastest growing outlet. Around 40 percent of composted product went to agriculture in 2003/04, and the quantity used in agriculture increased from 0.29 mt in 2001/02 to 0.48 mt in 2003/04 (67 percent increase). Landfill engineering and land restoration combined used 24 percent of wastes composted in 2003/04, while the remainder (36 percent) was distributed between horticulture, amateur gardening, landscaping and grounds maintenance.
Results from The Composting Association surveys have shown that over the last ten years, the UK composting industry has grown considerably. However, compared to previous years the growth rate in annual throughput from 2001/02 to 2003/04 had decreased while the growth rate in the number of sites had increased. In order to meet the challenges ahead, not only does the industry need to sustain this growth, it needs to expand the rate of growth observed over the last two years, and it needs to develop its capacity to process both the green waste and food waste fractions. A considerable growth in small, dispersed facilities was observed during 2003/04, which is beneficial as they enable the treatment of waste near to where it is produced. This growth needs to be complemented by the development of large-scale facilities that are able to treat more difficult and greater quantities of feedstocks. The costs of food wastes treatment are affected by increased legislative demands and the necessity of in-vessel technologies. The capital investment required (and on-going operational costs) can only be justified to finance lenders, if there is a guaranteed, long-term supply of large quantities of organic wastes, and end-uses for the composted product. Inevitably, diverting difficult municipal feedstocks from landfill will necessitate larger facilities, which will require the support of the planning authorities and regulators, coupled with more local authorities providing appropriate curbside collection facilities.
The Environment Agency and the Waste Resources Action Programme supported the research and publication of The State of Composting in the UK 20003-2004. The report, “The State of Composting in the UK 2003-2004” can be ordered through The Composting Association website www.compost.org.uk for £15/$30 (members) and £30/$60 (nonmembers) + £15/ $30 shipping and handling. Note: This survey can be downloaded at no charge as a pdf – visit www.compost.org.uk.
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NATIONAL COMPOST STANDARDS, MECHANICAL AND BIOLOGICAL TREATMENT
THERE WERE large geographical variations in the quantity of wastes composted across the UK. The largest increase in throughput was observed in England. However, the quantity of material processed tripled in Scotland and doubled in Wales, and all nations were similar on a per capita basis. The greater growth may be due to initiatives targeted at the biodegradable waste fraction. Scotland has already implemented new waste management regulations lowering the waste management license exemption limit to 400 tonnes at any one time from 1000 cubic meters, and uses the BSI PAS 100 as a benchmark for distinguishing compost product from waste. There are also several key differences in Wales, which has a separate target for source separated compostable wastes, different planning guidance and funding routes, and will not allow local authorities to trade biodegradable landfill allowances.
A large proportion (45 percent) of biodegradable wastes were composted at sites that met at least one nationally recognized standard. Compost producers recognize the benefits of voluntary standards and self-regulation. Objective technical standards and third party compliance programs have increased the overall confidence in the industry. Specifications such as the British Standards Institution Publicly Available Specification for Composted Products (PAS100) can provide a platform to expand markets, ensuring consistent product quality. However technical standards could play a much a wider role, for example,The First Soil Action Plan for England (2004- 2006) encourages the return of organic matter to the soil, and protection against contamination, which could be achieved through the promotion of certified composts.
Mechanical and Biological Treatment (MBT) is a well-established technology throughout Europe, and many countries that have implemented separate organic waste collection programs also rely on MBT to stabilize residual biodegradable waste prior to landfill. Only six operational sites were recorded by the survey, and these treated a total of 71,000 tpa. Nevertheless, there is considerable interest in the UK about the potential future role of MBT, sparked by recent policy measures together with potential fines for local authorities failing to meet landfill diversion targets. However, there are many uncertainties about the role of MBT, especially in relation to the use of stabilized residues within the context of the EU’s developing Thematic Strategy on Soil Protection. The technology could make a significant contribution to meeting the biodegradable limits set under the Landfill Allowance Trading Scheme (LATS) by enabling large volumes of biodegradable wastes to be treated. However, the uncertainties are likely to make them difficult to finance, especially as MBT plants are unable to claim renewable obligation certificates (ROCs) which exclude refuse derived fuel (RDF), and residues may not meet the definition of compost required to count towards Best Value Performance Indicators.