BAN Waste Select Committee evidence

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Phase 1 Day 4 2001-10-08 Matthew Pumfrey (Director Orrtec Ltd, Director Zero Waste International)

written evidence submitted in advance


This document touches on some of the issues facing the composting industry at the current time. These issues need to be addressed if successful composting programmes are to be developed in the UK.

Home composting has not been included within this document.


Dealing with the organic components of the waste stream is seen by many as the key to hitting the UK's recycling targets. This is unsurprising as organics can make up to 60% of the waste stream.

There are a number of ways to deal with these organic components of the waste stream and an integrated approach has to be taken to deal with this material. As in other areas of the waste management industry there is no one solution to dealing with the organics question. Each community must determine the most pertinent technology, either low or high tec, that will deal with their organics issues.

However it is not just the composing technique that determines the success of an area's organic waste recovery. Both suitable collection systems and end product markets have to be investigated and developed to ensure that the composting facility runs efficiently and successfully.

The technology required can only be determined once the material to be recovered and the end markets have been identified. The treatment process of organic waste is ultimately justified by the fate of the end product.

Current Disposal of Organics

One of the main reasons we are faced with the waste industry problems of today, is our insistence on mixing organic wastes with inert wastes. By doing this we limit the amount of time we have to 'deal' with this material before we are faced with issues surrounding the degradation of the organics.

When organics decompose in an uncontrolled way, odour, vermin, vector and health and safety issues are created which means that the mixed waste has to be disposed of as quickly and safely as possible.

This has resulted in the development of 'sanitary' landfills and incinerators to deal with mixed wastes as efficiently and swiftly as possible. The waste industry has developed very successful processes to deal with waste in these ways, but at the same time as we let them 'deal' with this waste we are also loosing vital resources and opportunities.


Current farming methods are linear. Trace elements and minerals are removed from the soils within crops being harvested. Through the current intensive farming regimes not only are these compounds being removed, but also the soil is being stripped of microbial populations, organic content and many other physical and biological properties that reduce soil health.

Our farming system then only replaces N, P and K, with minimal, if any, replacement of the plethora of other trace elements and minerals also lost. There is also little concern over the microbial health of the soil and maintaining it is vital for healthy crop production. The UK's intensively farmed land has lost up to 80% of its organic content in the last few hundred years. This effects soil health, water holding capacity and many other characteristics which reduces the ability of the land to supply our needs.

If we continue down this route and don't replace vital compounds and improve our soils' health we will end up with soils that are akin to hydroponic growing media which will become wholly unsustainable.

Organic Wastes

Organic wastes come in many forms, from greenwaste and timber wastes, through food wastes, paper and cardboard to sewage sludge and other biosolids. All of these materials can be successfully recovered with appropriate technologies.

Recovery techniques are varied. At one extreme there is recovery from reuse through low-tech solutions such as chipping to produce mulches. There are then the traditional composting techniques of static piling and windrow composting. At the other end of the scale are higher tec technologies such as in-vessel composting and anaerobic digestion.

The Composting Process

The composting process is a complex range of chemical and biological reactions that are inter linked, converting organic wastes through a series of steps to humus and humic acids. However for the layman the composting process can be viewed as a relatively simple process where there are three main parameters. These are:

  1. Carbon:Nitrogen Ratio
  2. Moisture Content
  3. Porosity

By getting these three parameters right it is relatively easy to compost organic wastes, although the form, e.g. windrowing or in-vessel, will need to be determined depending on the material being composted.

With the processing of some wastes other issues impact on processing, such as odour and leachate production and vector and vermin attraction. As a result there are a variety of techniques that can be employed to overcome these issues to ensure the safe recovery of organics.

Composting Technologies and Techniques

There are a plethora of techniques and technologies out in the market for the composting of organic waste. Many are simply a twist on a similar theme and as a result it will come down to the capital and operational costs of a plant to determine its pertinence for a particular waste stream.

Broadly speaking there are five main methods of recovering organics. These are:

A process where raw or physically treated organic wastes are spread directly onto the land without any biological treatment. A common route for many hundreds of years, especially for agricultural wastes. However in recent years this form of disposal has been closed off for many organic wastes.

A simple technique used for animal wastes and some greenwaste and woody wastes. Material simply left in a pile to degrade naturally over an extended period.

Next stage on from static piling. Turning regime and some monitoring of the pile is maintained. Normally only animal manures, wood and greenwastes are composted this way. Some mixed putrescible and greenwaste composting is carried out in this way, but often faces odour, vermin and pathogen issues.

Systems where organics are fed into enclosed and normally PLC controlled containers. Although often capitally and operational more costly than windrow composting they can be used to processes the more putrescible fraction of the waste stream under more controlled conditions that can ensure sanitisation and prevent the production of odour and leachate.

Vessel utilising anaerobic bacteria to degrade organic wastes to generate methane for use. Used extensively within the waste water industry, but only small scale within the putrescible solid waste industry.

Collection Systems

Collection systems are often overlooked within the composting sector but the collection of the organics is arguably the most important stage of the recovery process. This stage often determines the quality of the end product and thus the potential end markets.

Organics, especially putrescibles, need to be collected in a suitable vessel that will limit odour and vermin attraction whilst allowing operators to easily determine if the container contains contaminated organics or not. In the last 5-10 years degradable sacks have become far more popular within these collection systems as both they and their contents can be readily composted.

Collection systems also need to utilise suitable collection vehicles for the material. For example many systems world-wide have started with compactor trucks only to find liquor leaking from the back of the vehicle resulting in costly modifications to the collection system after services have started.

Market Development

Market development is often seen as the biggest hurdle in developing the UK composting market. But this is unsurprising when many composting operators expect to put little time and effort into the processing system and then produce a product that customers will buy.

The compost operator needs to understand he is no longer a waste manager, but more a product manager of compost products. With this in mind quality assurance systems need to be developed that will allow for the development of a brand, be it local or national, that will attract customers and build the loyalty for future sales and thus survival.

There is a view that there is no market for compost products in the UK, but far from it. Those companies that have approached the process in the right way have proved to be a great success. Indeed one large scale operator in Leicestershire has said they could quadruple their current output, some 15,000 tonnes per annum, overnight if they could source the material.


This is the big unknown. The reticence of the Environment Agency to guide the industry with pertinent regulations has stymied the development of the industry in the UK. There is a wide range of legislation from the European Union as well as UK Central Government impacting on the composting industry, but behind it all is an understanding that if we do not develop large scale organics recovery we will not reach the statutory recycling targets.

There are a number of legislatory papers affecting the industry as it stands at the moment, these include:

  1. The EU Landfill Directive
  2. Animal By-Products Order
  3. Draft Bio-Waste Directive
  4. Landfill Tax Scheme

There has been much development of this legislation in the last 5 years and this will continue in the coming years. It is likely that land spreading of any untreated organic waste will be banned and the use of static piling and windrowing will be restricted to agricultural manures, greenwaste and woody waste. All putrescibles are likely to have to be processed through controlled in-vessel systems to ensure sanitisation.


In summary there are a number of areas that have to be reviewed when developing composting facilities that can initially seem daunting. But as with all recycling systems a phased approach will overcome these issues and ensure the composting process being developed is appropriate for the materials being recovered and the end markets being developed.