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GlossaryGlossary of Terms


Animal By-Products Regulations (ABPR)

The European Union's Animal By-Products Regulations lay down health rules as regards animal by-products and derived products not intended for human consumption. For more information see the Wikipedia article.

Aerobic Composting or Aerobic Digestion

Aerobic composting is the controlled biological decomposition of organic materials under aerobic conditions, accomplished in open windrows, open static piles or in-vessel. Composting involves the action of thermophilic ("heat loving") micro-organisms that thrive under increased temperature conditions and if correctly managed, this can allow for the destruction of disease-causing organisms.


Area of High Landscape Value (Designated by Local authority)


Area of Outstanding Natural Beauty (designated by the Countryside Agency now part of Natural England).

Anaerobic Digestion

The biological degradation of organic material in the absence of oxygen. By-products include a methane-rich biogas and biofertiliser.


Best Practicable Environmental Option (BPEO)

The BPEO procedure establishes for a given set of objectives, the option that provides the most benefits or the least damage to the environment, as a whole, at acceptable cost, in the long term as well as in the short term.

Best Value

A statutory duty on local authorities to deliver services, including waste collection and waste disposal management, to clear standards on both cost and quality.


Biodiversity is about the whole range of living things from well known trees, flowering plants, birds, animals and butterflies to lesser known mosses, lichens, fungi, marine species and even bacteria. Biodiversity is also about the wide range of habitats that these animals live in and depend upon.


Solid, liquid or gaseous fuel that is derived or produced from biomass. Biomass that has been processed or converted in some way into a more convenient form, principally to increase energy density. This may involve physical pre-processing simply to cut it into more manageable pieces or reduce the moisture content, or may involve thermal or chemical processing to convert it into a solid, liquid or gas.


A mixture of methane ( CH4 ) and carbon dioxide ( CO2 ) produced by anaerobic digestion, with small amounts of other gases. The methane is a flammable gas, like natural gas, and can be used for heat and/or electricity generation. Biogas is effectively the same as landfill gas, produced by the anaerobic decomposition of organic material in landfill sites.


Material that is derived from living, or recently living biological organisms. In the energy context it is often used to refer to plant material, however by-products and waste from livestock farming, forestry, horticulture, food processing and brewing, can all form sources of biomass.

Biological Resource Recovery Processes

Biological resource recovery processes cover a range of technologies to stabilise organic waste. The first is a 'pre-treatment' stage where mechanical processes are used to shred, screen out metals and plastics from the organic material, which is then composted.

Bling Systems

A system of buying cheap tacky presents for those "who have everything"; often at Christmas in a frenzy. Usually ends up in wheelie bins within a few days.

Bring Systems

A system by which the public deliver their recyclables to a central collection point, such as those in supermarket car parks, or at civic amenity sites.

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Carbon Cycle

The cycle by which carbon in various forms moves between the various components of the Earth's biosphere, between the atmosphere, hydrosphere (seas and oceans), lithosphere (rocks, soils and mineral deposits, including fossil fuels) and biological material including plants and animals.

Carbon is constantly moving between some of these forms, maintaining a state of dynamic equilibrium. Other forms, most notably fossil fuels, can potentially store carbon indefinitely, however if they are burned the carbon is released and makes a net addition to the carbon cycle and raising the total free carbon.

If biomass is used without replacement, as for instance can happen in the case of forest clearance such as in the Amazon rain forest, this too can make a net addition to the carbon cycle. Sustainable use of biomass, however, makes no such direct net addition as growing replacement plant material absorbs the carbon released by the harvested biomass.


Chromated Copper Arsenate (CCA). A water-borne, combined fungicide and insecticide that includes arsenic for the treatment of wood. It was developed in 1933 and has been used widely in the UK and around the world.

The arsenic is emitted to the atmosphere from flue gases during combustion if treated wood is burned. It is difficult to trap with conventional filters so CCA treated timber must not be burned except in suitable equipment.

Modern, less toxic alternatives are now widely available.

Civic Amenity Sites

These sites are where the public deliver their waste and recyclable materials to a central collection point.


Experts in living off recycled materials.


The calculated and monitored treatment by disposal of special waste with other non-special waste, usually household but could include industrial and commercial waste in a landfill.

Combined Heat and Power (CHP)

The heat associated with electricity generation is used for space heating or process heat. The efficiency of the process for energy from biomass fuel is increased considerably. Also known as co-generation.


Combustion (or incineration as it is commonly referred to) is the conversion of organic material and reduction of the volume of solid wastes by the use of an enclosed device using controlled flame combustion.


Chopping up material, such as biomass, into small fragments.


Compost is the material that results from the composting process and is a dark, moist soil-like substance that enriches the nutrient content of soil and helps soil structure.


Composting is the controlled breakdown or decomposition of organic materials under aerobic (i.e. with air) or anaerobic (i.e. without air) conditions. Composting allows the good 'bugs' to wipe out the 'bad' bacteria.

The scale of composting ranges from small garden composters to large-scale centralised facilities, which can compost materials from many thousands of households.

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Department for Environment, Food and Rural Affairs.


A family of 210 chlorinated compounds. 17 of the compounds are toxicologically significant and are carcinogenic. Dioxins are a by-product of many combustion process, such as household and trade waste incineration.

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Embedded Energy

The total amount of energy used in the production of a fuel or product. For woodfuel this may include contributions from land preparation, planting, fertilizer and pesticide inputs, thinning, harvesting, comminution, processing and transport.

This is why the combustion of paper and cardboard is less energy efficient than virgin wood/biomass.

Energy Density

The amount of energy stored per unit volume (volume energy density) or mass (mass energy density) of a fuel. A high energy density generally makes storage and transport of a fuel more convenient. Fossil fuels typically have higher energy density than solid or wet biomass fuels, though converted liquid biofuels and biogas are similar to those of their fossil counterparts.

Energy from Waste (EfW)

The conversion of waste into a useable form of energy, e.g. heat or electricity. Common conversion processes are incineration and anaerobic digestion.

Environment Agency

Aims to prevent or minimise the effects of pollution on the environment and issues permits to monitor and control activities that handle or produce waste within the scope of the Environmental Protection Act 1990.

It also provides up-to-date information on waste arisings and the extent of, and need for management and disposal facilities.


Energy supply company. Sells heat to the customer instead of a boiler and/or fuel. May install, own and maintain the boiler, or may sub-contract some or all of that. Heat used by the customer is metered, usually as hot water flow rate and temperature difference between outflow and return. Fully responsible for ensuring continuous operation and suitable quality fuel supply. Particularly well suited to district, site or large or multiple building heating systems.

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Input material for the digestion process.

Fly Tipping

The illegal and uncontrolled disposal of waste to land.

Fly Fishing

By J R Hartley.

Food Waste

Food waste is waste that comes from the preparation of food and consists of fruit/vegetable scraps, dairy, meats and breads and other starchy foods. Food waste is generated from households and restaurants, hotels and other commercial premises that prepare food.

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Gasification is the breakdown of waste materials using a combination of high heat (i.e. gasification) and combustion. One method is called pyrolysis; the thermal decomposition of organic material either in the absence of air or with a very small amount of air. Pyrolysis generates three main products; char, oil ('pyrolysis oil') and gas. These products vary depending on the composition of the waste materials fed into the pyrolysis reactor and process conditions (e.g. amount of oxygen).

Another method called Gasification is the process whereby most of the char, tar and volatile gas resulting from pyrolysis are converted into a steam and a combustible gas (syngas) by a reaction with steam, with or without air.

Green Waste

Green waste includes the garden trimmings, lawn mower clippings, leaves, shrubs, plants, tennis balls and other organic waste from domestic gardens, parks, sports grounds and commercial premises.

Greenhouse Effect

The effect of trapping heat by the transmission of visible solar energy, and the absorption (or reflection) of infra red heat energy.

The greenhouse effect is beneficial to mankind as well as harmful as, without it, the surface of the earth would be around 33°C cooler than it is. The majority of this is natural, changes very slowly and consequently the earth's ecosystems have evolved to function best with the greenhouse effect at this natural level.

However, since the Industrial Revolution and the rapidly increasing use of fossil fuels, atmospheric levels of greenhouse gases - particularly carbon dioxide (CO2) - have increased extremely rapidly to the highest level they have been at for 650,000 years.  This is because carbon that was removed from the atmosphere many millions of years ago (and which resulted in a reduction of atmospheric CO2 levels then) is now being extracted as coal, oil and natural gas and returned to the atmosphere.

Greenhouse Gas (GHG)

Any one of a number of gases that trap heat in the earth's atmosphere in a similar way to which the glass traps heat in a greenhouse. They work because they transmit light at the visible wavelengths that form the majority of the sun's energy incident on the surface of the earth.

When the surface of the earth absorbs this and warms up it re-radiates heat energy at much longer wavelengths (in the infra red) and this is absorbed by GHG molecules such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), ozone (O3) and water vapour (H2O).

Although carbon dioxide is the most widely known about, as it is responsible for the majority of anthropogenic climate change, other GHGs have a much greater greenhouse gas potential per molecule.


An important part of the natural water cycle and present within underground strata known as aquifers. Groundwater has a substantial strategic significance in public water supply.

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Hazardous Waste

Hazardous waste comprises of those materials that pose a threat or risk to public health, safety or to the environment (e.g. batteries, paints, solvents, engine oils and fluids, cleaners etc.)

Household Waste Recycling Centre (HWRC)

A facility provided by the Waste Disposal Authority which is available to the public to deposit waste which cannot be collected by the normal household waste collection round. Also referred to as Civic Amenity Site or Household Waste Disposal Compound.

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Incineration disposes of solid wastes, such as MSW, by burning. A 90% reduction in volume and 50% reduction in weight can be achieved.

The combustion process produces gaseous carbon dioxide (CO2), nitrous oxides (NOx), hydrofluorocarbons (HFCs), Persistent Organic Pollutants (POPs) and water vapour (H2O). In addition there is grate-ash that is used within the construction industry and toxic fly-ash that is deep buried in sealed containers.

Energy is produced, however on balance this is less than the energy used to replace the burnt materials.

Integrated Pollution Prevention Control (IPPC)

Designed to prevent or reduce pollution by integrating permitting processes based on the application of best available techniques (BAT). It gives priority to prevention at source, and ensuring prudent management of natural resources, in compliance with the "polluter pays principle". The Directive covers emissions to air, land & water.

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Kerbside Collection

The collection by the local authority of recyclable goods directly from households, or occasionally industrial or commercial premises.

Kerb Crawling

Slow moving Refuse Collection Vehicles.

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The controlled deposit of waste to land.

Landfill Directive

Set of European Community Rules on landfill to ensure high standards for disposal and to stimulate waste prevention, via recycling and recovery.

Landfill Gas

The gas generated in any landfill site accepting biodegradable organic matter. It consists of a mixture of gases, predominantly methane and carbon dioxide.

The mixture of gases produced from the anaerobic breakdown of organic material in landfill. Typically consists of 50-60% methane (CH4), 30-40% carbon dioxide (CO2), 10% nitrogen (N2), small amounts of other volatile organic compounds (VOCs).

Methane is a very potent greenhouse gas, 21 times more so than carbon dioxide. It can have an offensive odour due to traces of organosulphur compounds and is explosive.

Landfill Tax

Landfill tax was introduced to financial encourage alternatives to the traditional burying of household and trade refuse. The reasons given were to reduce atmospheric emissions of methane, a potent "greenhouse gas", to reduce groundwater pollution and to encourage recycling.

Modern engineered landfill facilities uses sealed cells that contain leachate and landfill gas - a useful fuel for electricity generation. In theory, once the chemical and biological activity within has ceased, the contents could be excavated to recover plastic, fibre and metals.

Every year since April 2001, landfill tax has risen at a rate of £3.00 per tonne.

An incineration tax is now being considered to compliment Landfill Tax, to increase environmental protection and recycling rates.

In addition there has been a general increase in landfill charges with landfill operators needing to recover the extra cost brought about by the fuel price increases and extra environmental protection measures.


A liquid solution that forms when rain and ground water percolates through waste, such as refuse in a landfill or old mining tailings. It may contain any chemicals that can be dissolved, particles and even live micro-organisms.

Life Cycle Assessment

A method for evaluating the materials, inputs and emissions relating to the whole life of a product from raw material acquisition, through manufacture, distribution, retail, use, re-use, maintenance, recycling and waste management. Environmental impacts and costs are taken into account. Life-cycle analysis involves the collection of data to produce an inventory, life-cycle assessment to the evaluation of the output.

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Material Recycling Facility (MRF)

A specialist plant which separates, processes and stores recyclables which have been collected either separately from waste (a "clean" MRF) or unsorted (a "dirty" MRF).

Moisture Content

The proportion of water in a sample of biomass, defined as the weight of water as a percentage of the weight of biomass. This can be defined on either a wet basis, as a percentage of the total (wet) weight of the sample, or a dry basis, as a percentage of the oven dry weight of biomass. Wet basis is usually used for fuel purposes.

Materials Recovery Facility (MRF)

Materials Recovery Facility (MRF) is a centre that receives and separates recyclable materials such as glass, plastic, steel, aluminium and paper that are collected from household recycling bins and recyclable materials from commercial premises. Recyclable materials at an MRF are separated and sent away to be processed into new products.

Municipal Solid Waste (MSW)

Municipal Solid Waste (MSW) is household waste that is set aside for kerbside collection or delivered to a waste facility through a drop-off program. MSW also includes other types of waste such as bulky household waste (e.g. appliances, furniture and residential garden waste), household hazardous waste or waste generated from local Council operations (e.g. waste from street sweeping, litter bins and parks).

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Organic Waste

Organic waste is the term used to describe those wastes that are readily biodegradable, or easily breakdown with the assistance of micro-organisms. Organic wastes consist of materials that contain molecules based on carbon. This includes food waste, green waste, putrescible waste and also wastes arising from grease traps. Organic waste however, does not include for example, plastic or mineral oil products.

Organisations & Agencies

ADAS (National Agricultural Advisory Service)
The UK's largest independent provider of environmental consultancy, rural development services and policy advice.

Carbon Trust
The Carbon Trust was set up by Government in 2001 as an independent company, to accelerate the move to a low carbon economy now and develop commercial low carbon technologies for the future.

Country Land and Business Association (CLA)
The CLA is the membership organisation for owners of land, property and businesses in rural England and Wales.

Department for Environment, Food and Rural Affairs (DEFRA)
DEFRA is the UK government department responsible for policy and regulations on the environment, food and rural affairs.

Energy Saving Trust (EST)
EST is a non-profit organisation jointly funded by the British Government and the private sector in order to help fight climate change by promoting the sustainable use of energy, energy conservation and to cut carbon dioxide emissions in the United Kingdom).

Environmental KTN (Knowledge Transfer Network)
The Environmental KTN draws together organisations and businesses that deal with environmental pollution in land, waste and water and assists industry to meet the demands of regulatory and business drivers for the integrated management and remediation of environmental pollution.

MAFF (Ministry of Agriculture, Fisheries and Food)
The MAFF was a United Kingdom government department which was dissolved in 2002, at which point it's responsibilities had been merged into the Department for Environment, Food and Rural Affairs (DEFRA).

National Industrial Symbiosis Programme (NISP)
NISP is a free innovative business opportunity programme delivering triple bottom line, environmental, economic and social benefits across the UK.

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Persistent Organic Pollutants (POPs)

These are chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment.

With the evidence of long-range transport of these substances to regions where they have never been used or produced and the consequent threats they pose to the environment of the whole globe, the international community has on several occasions called for urgent global actions to reduce and eliminate releases of these chemicals.

Pollution Prevention Control (PPC)


Producer Gas

The mixture of gases produced by the gasification of organic material such as biomass at relatively low temperatures (700 to 1000°C). Producer gas is composed of carbon monoxide (CO) and hydrogen (H2) plus carbon dioxide (CO2) and typically a range of hydrocarbons such as methane (CH4).

Producer gas can be burned as a fuel gas such as in a boiler for heat or in an internal combustion gas engine for electricity generation or Combined Heat and Power (CHP). The composition of the gas can be modified by choice of gasification parameters to be optimized as a fuel gas (producer gas) which contains almost exclusively CO and H2 and is suitable for synthesis of liquid biofuels.

Producer Responsibility Obligations

Requires those producing and selling goods to take greater responsibility for those goods at the end of the products life.

Proximity Principle

Waste should generally be disposed of as near as possible to its place of production. This reduces the cost, carbon footprint and pollution from transport.


Power take-off. Drive shaft from tractor, horse vehicle or other vehicle engine used to drive ancillary machinery. Can be used to power some wood chippers.

Putrescible Waste

Putrescible waste includes household food waste; green waste and certain wastes arising from commercial and industrial sources. This kind of waste will easily decompose and breakdown.


Bio-oil is produced by fast pyrolysis of biomass. A dark brown, mobile liquid containing much of the energy content of the original biomass, with a heating value about half that of conventional fuel oil. Can be burned directly, either alone or co-fired with other fuels, gasified or otherwise upgraded.

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In general, recyclables are those materials that can be recycled into the same or new products. Currently these include glass, metals, paper, cardboard and some plastics. Recyclables are often referred to as those materials that are placed in household recycling bins and collected through Council collections. Recyclables can also be collected from public place recycling bins and recycling bins used by commercial premises.


Recycling is the process where recyclable materials (e.g. paper, plastic, glass, metal, aluminium, steel etc.) are converted into new products, which are suitable to replace the same or new products made from virgin materials (e.g. waste paper into office paper and cardboard, aluminium soft drink cans into new cans, plastic bottles into plastic utensils etc.)

Refuse-Derived-Fuel (RDF)

Also known as Waste Derived Fuel (WDF). A fuel product produced from the combustible fraction of household waste.

Refuse Collection Vehicle (RCV)

A vehicle used to collect waste, such as a dustcart.

Regional Self-Sufficiency

Most waste should be treated or disposed of within the region in which it is produced.

Residual Waste

Residual Waste is the material in peoples' rubbish bins after they 'do the right thing' through reducing, re-using, recycling, home composting and/or garden waste collections.

Resource Recovery

Resource recovery means recovering resources from waste. There is a range of different resource recovery technologies that can change waste materials into resources, through thermal or biological means. Resource recovery technologies result in many useful products such as fuel, soil conditioner, compost, energy and chemicals for manufacturing new products (often referred to as Secondary Resource Recovery [SRR] or secondary waste treatment).


Resources can be materials, products or waste that has potential value and can be used to process new useful products.

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Small and Medium Enterprises.

Source Protection Zones

The Environment Agency has identified three groundwater Source Protection Zones. Zone I (Inner Source Protection); Zone II (Outer Source Protection) and Zone III (Source Catchment).

Zone I (Inner Source Protection) is located immediately adjacent to the groundwater resource. It is designed to protect against the effects of human activity which might have an immediate effect upon the source. This area is defined by a 50-day travel time from any point below the water table to the source and as a minimum of 50 metres radius from the source. This 50 day travel time zone is based on the time it takes for biological contaminants to decay.

Zone II (Outer Source Protection) is larger than Zone I and is the area defined by a 400 day travel time from any point below the water table to the source. The travel time is based upon that required to provide delay and attenuation of slowly degrading pollutants.

Zone III (Source catchment) covers the complete catchment area of a groundwater source. All groundwater within it will eventually discharge to the source.

Sustainable Development

Development which meets the needs of today without compromising the ability of future generations to meet their own needs.

Synthesis Gas or Syngas

A mixture of carbon monoxide (CO) and hydrogen (H2) which is the product of high temperature gasification of organic material such as biomass. Following clean-up to remove any impurities such as tars, synthesis gas (syngas) can be used to synthesize organic molecules such as synthetic natural gas (SNG - methane (CH4) ) or liquid biofuels such as synthetic diesel (via Fischer-Tropsch synthesis).

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Tonnes coal equivalent. A measure of energy used to relate different fuels to the equivalent coal requirement based on an energy value for coal of 42 MJ/kg.


Tonnes of oil equivalent. A measure of energy used to relate different fuels to the equivalent oil requirement based on an energy value for oil of 42 MJ/kg.

Thermal Resource Recovery Processes

Incineration with energy and materials recovery.

Thermal Treatment

Incineration or burning.

Transfer Stations

Transfer stations are facilities where collection vehicles deposit waste and/or recyclables collected from elsewhere. Waste or recyclables taken to a transfer station are then put into larger transfer vehicles for transport to a landfill site or resource recovery facility. Transfer stations may be used by both persons and vehicles and also may include recycling facilities and facilities for compacting and bailing waste and recyclable materials.

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Process where waste is eaten and converted by worms.


Vermicomposting is the breakdown of organic material that, in contrast to composting, involves the joint action of earthworms and micro-organisms and does not involve the generation of high heat, as with composting. The worms consume organic wastes such as food waste, animal waste and sewage sludge; and turn and fragment the waste, which produces a soil conditioner.

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Waste is unwanted materials or products, which are considered to be no longer useful. Wastes can be disposed of in a rubbish bin and/or a landfill site but many such 'wastes' have value and can become resources to be used to generate many different useful products such as energy or compost.

Waste Collection Authority

Borough/District Councils: Durham City, Sedgefield, Easington, Wear Valley, Chester-le-Street, Teesdale, Derwentside. All have a duty to collect household waste except in certain prescribed areas. They also have a duty to collect commercial waste if requested to do so and may also collect industrial waste.

Waste Disposal Authority

Unitary or County Council responsible for providing disposal sites.

Waste Hierarchy

This is a theoretical framework that acts as a guide to waste management options that should be considered when assessing the BPEO.

Waste Planning Authority

Unitary or County Council responsible for ensuring that an adequate planning framework exists. They are required to prepare a Waste Local Plan and also have responsibility for determining planning applications for waste management facilities.

Water Table

The top surface of the saturated zone within the aquifer.


Open linear heaps of material associated with large scale centralised composting.

Waste Minimisation

Waste minimisation includes those activities that aim to reduce the amount of waste that is generated and the amount of waste that is disposed of or land filled. Waste minimisation includes avoiding and/or reducing the generation of waste in the first place, re-using waste, recycling waste and recovering waste through resource recovery.

Waste Stream

Waste stream is the flow or movement of wastes from the point of generation (i.e. household or commercial premises) to final disposal (i.e. landfill). A waste stream may reduce significantly over time as valuable items are separated for recycling and are recovered through resource recovery.

Waste To Energy (WTE)

Also known as Energy from Waste (EfW)

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