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Organic and Food

INTRODUCTION

Organic and food waste is made up of a variety of waste types from a wide range of sources. Green waste generally includes vegetation and plant matter arising from household gardens, local authority (LA) parks and gardens, and commercial landscaped gardens.

Foodstuffs are a similar though separate waste stream and they include waste and surplus food, fats and oils. Food waste is produced by canteens, restaurants, fast food outlets, shops, hotels, schools, households, abattoirs and food manufacturers.

The majority of organic and food waste is disposed of at landfill sites and represents one of the most difficult waste management problems in landfill. Once in landfill, these wastes decompose anaerobically (i.e. in the absence of air) and form landfill gas. The primary component of landfill gas is methane, which is explosive and acts as a powerful 'greenhouse' gas. Consequently, modern landfill sites require gas migration controls to prevent gas seeping to surrounding areas.

Decomposing organic and food wastes contribute to leachate which accumulates in landfills. This toxic cocktail has the potential to cause serious groundwater and surface water pollution and must be collected and treated. Decomposing organic matter also produces the characteristic smell of landfill which is liable to attract scavenging birds and vermin.

Landfilling of biodegradable organic and food waste also represents the loss of an important resource. This is particularly the case for green waste which is ideal for producing compost. Compost from waste organic material can offset the use of peat (demand for which is currently placing peat resources in jeopardy). There is an urgent need to preserve peat bogs in the UK and the use of peat-free alternatives is a more environmentally sustainable alternative.

Cooking oil is another problematic component of food waste and can be classified as either liquid (e.g. refined and unrefined vegetable oils) or solid (e.g. lard, dripping and hydrogenated vegetable oils). Often produced in large quantities by restaurants, food processors and canteens, the disposal of cooking oils can be difficult but there are no special requirements or regulations. These wastes have the potential to coagulate in sewers if disposed of down sinks and drains. They also have the potential to coat vegetation and wildlife if allowed to enter water courses, which can inhibit growth and limit respiration.

FACTS AND FIGURES

The UK produces an estimated 5 million tonnes of green waste per year (DETR 1999b) Waste cooking oil makes up 100,000 tonnes of this total (Oil Recovery Association 1999).

Composting green waste is a viable alternative to landfill. As shown in Table 1, the amount of green waste composted in 1997 was approximately 460,000 tonnes (DETR 1999b), a dramatic increase from the 60,000 tonnes composted in 1993 (Waste Management Year Book 1998).

Table 1 Sources of Green Waste

SOURCES AMOUNT COMPOSTED IN 1997 (TONNES)
Source separated household garden waste collected from the kerbside 28,280
Household garden waste deposited at civic amenity sites 343,964
Green waste from LA parks and gardens 15,800
Non-differentiated landscape/park/household green waste 73,000
Total 461,044

SOURCE: DETR 1999b


Although composting increased through the 1990s, less than 4% of organic house-hold waste in the UK is treated by this method, compared to 44% in Germany (Waste Management Year Book 1998). The UK currently ranks seventh in Europe in composting terms with the Netherlands, Austria and Denmark achieving the highest composting rates (Project Integra 1999).

The two main composting options are centralised schemes and home composting. The amount of waste collected for centralised composting in the UK has more than doubled in two years to 380,000 tonnes in 1997-98. In addition, LA estimates suggest that between 200,000-300,000 tonnes of waste are composted at home (DETR 1999b).

In 1997 there were 39 fully operational composting sites in the UK and a further 12 partly operational, under construction or planned (DETR 1999). This has grown to 80 in 1999, and it is likely more facilities will be developed to meet targets for the Landfill Directive (see European Legislation Affecting Waste Management). In addition to composting green waste, these sites also accept kitchen waste separated at source.

A large source of waste for centralised composting schemes comes from household garden trimmings brought to civic amenity sites. In 1997-98 approximately 165,000 tonnes of this waste stream was composted (Waste Management Year Book 1998). Local Authority parks and gardens are another source of compostable waste with approximately 25,000 tonnes composted in 1997-98 (DETR 1999b).

LEGISLATION

For organisations with large arisings of organic waste there is increasing impetus to minimise this waste and to find alternative options to landfill. This is largely due to the imposition of the landfill tax and, more recently, the requirements of the landfill directive. These measures have focused the efforts of both commercial organisations and LA s to reduce the amount of organic and food waste ending up in the dustbin.

LANDFILL DIRECTIVE 1999/31/EC

The recently adopted Landfill Directive (1999/31) will require substantial changes to the way in which waste is managed in the UK. It seeks to reduce the hazardous nature and the volume of waste being sent to landfill and bans certain wastes completely. The directive requires the reduction of biodegradable municipal solid waste sent to landfill. The target for biodegradable waste is a 35% reduction on 1995 figures to be achieved by 2016.

LANDFILL TAX REGULATIONS 1996 (AS AMENDED)

The Landfill Tax Regulations (as amended) (SI 1996/1527) were introduced in October 1996 to promote sustainable waste management and increase the cost of landfill disposal to reflect the environmental impact of this option. There are two rates of tax:

In the 2000 budget the Chancellor announced that the landfill tax will rise by £1 per tonne each year (to be reviewed in 2004).

The tax aims to encourage the greater diversion of waste from landfill and to allow waste producers and managers to plan their waste management strategy for the future. Organic waste is an obvious target for this tax due to the problems associated with its decomposition in landfill and the potential to recycle it. The tax will increase the economic viability of composting when the cost of landfill is taken into account.

WASTE MANAGEMENT OPTIONS

REDUCE
Irrespective of the source, there are a number of opportunities to reduce food wastage. If food or organic waste is a major waste for an organisation or company, time must be taken to identify the source and to find options for reduction. Questions to consider include:

There are a number of ways to reduce wastage. For example, the possibility of selling unsold produce at a discounted price or donating it to organisations working with people in social need should be investigated. It may also be possible to use surplus food to make another product (e.g. bread pudding from unsold bakery bread).

Wastage is often the result of poor storage and refrigeration. Over-purchasing is often a false economy and a waste of resources if food is left to deteriorate. This is true for both industrial and commercial generators of waste as well as householders.

Householders may be tempted by 'value' offers and purchase larger quantities of food than is necessary. This should be avoided if it cannot be frozen or stored effectively prior to use.

Commercial organisations should negotiate with the supplier to try and purchase the correct quantity and quality.

Oil and fat should not be poured down sinks or drains as they have the potential to coagulate and create blockages in the water system. Instead, they should be stored separately and carefully managed to minimise possible health and environmental problems. It is always advisable to try to avoid excessive amounts of saturated oils and fats in a diet.

REUSE
Table 2 summarises a number of options for dealing with food waste. Food waste has the potential to be reused by pig farmers to produce swill for feeding stock. The farmer must have a license to boil waste food for swill under the Waste Food Order 1973 (amended). Before entering an agreement with a farmer it is necessary to check if he or she is licensed with the local Animal Health Office of the Ministry of Agriculture, Fisheries and Food (MAFF). The farmer's permission must be obtained for MAFF to release this information.

Table 2 Organic and Food Waste Management

TYPE NATURE OF MATERIAL AEROBIC COMPOST ANAEROBIC DIGESTION APPLIED TO LAND ANIMAL FEED OR INDUSTRY FEEDSTOCK DIRECT SALE OR DISTRIBUTION COMMENTS
Waste Food Solid/ Liquid Yes Yes Check animal feed outlets are licensed by MAFF
Surplus Often Yes Yes Packaging needs to be removed if sent for animal feed
Food Processing Waste Clean and often one type only Yes Yes Possible Possible Final option depends on composition. Only vegetable wastes can be composted
Abattoir Waste Blood/ solid Yes Yes Strict regulations apply
Landscape Wastes Plant origin Yes Possible Possible if pre-treated Small to large scale operations possible. Woody materials require shredding
Fats and Oils Clean Yes Collect separately
Office Organics Mixed Yes Home composting

SOURCE: SWAP, SURREY COUNTY COUNCIL 1996


Cooking oil can be reused a limited number of times for deep-fat frying before it needs replacing. In order to prolong its life, cooking oil can be drained through kitchen roll and a sieve to remove food contaminants. Continual reuse is not advisable due to increased health risks as the fat degrades. Oils and fats can also be collected on a larger scale which can then be purified and used as a calorie enhancer in animal feeds. These collections are not available to householders.

RECOVERY
Another viable alternative to disposal for organic and food waste is to return it to the land. There are two ways in which this can be done - through composting or anaerobic digestion.

Composting
Composting is an aerobic biological process for treating solid organic wastes. Micro-organisms are able to break down the organic material using the oxygen in the air to produce carbon dioxide, water and the stabilised granular residue known as compost.

Carbon [i.e. organic matter] + O2 + micro-organisms = CO2 + H2O + Heat + Compost

The resultant compost contains valuable organic matter and nutrients suitable for improving the structure, fertility and biological activity of soil. During this process a large amount of heat is produced. If the operation is designed and operated correctly, the temperature should rise sufficiently to inactivate pathogens, thereby sanitising the material (Stentiford 1999).

Organic waste from parks, households and estates will include prunings, trimmings, mowings and dead leaves. Only a small compost bin is required for these amounts of waste. In contrast, large-scale composting facilities used by local authorities for extensive amounts of collected waste will require suitable containers and planning permission.

Home Composting
Home composting is a traditional part of gardening culture in the UK and has been practised for generations in horticulture as a cheap and valuable means to recycle waste vegetation. Composting bins provide insulation and aeration. The end product, a crumbly, dark-brown, odourless material, is available after about 4-6 months, depending on the time of year.

Most plant remains can be composted with loose layers of mowings which should not be compacted. Heaps should be built in 25cm layers and mixed with kitchen waste such as vegetable and fruit peelings, tea bags/leaves and eggshells. Food likely to attract vermin, such as meat, should not be included. Diseased plant material and seeding weeds should not be composted, and grass treated with weed killer should only be composted if recommended by the herbicide manufacturer. Prunings and woody stalks should be finely chopped or shredded if they are to be composted, while large quantities of sawdust and wood shavings are best avoided as they have a compacting effect and take a long time to decompose.

Local authorities in the UK are encouraging the use of household composters for garden and kitchen waste. Local authorities are often acting in partnership with composter manufacturers to organise the sale of subsidised composters to householders. This is an effective way of reducing the organic fraction of household waste while increasing environmental awareness within a community.

Worm composting is a growing area of interest in the UK. Most commonly, red worms and tiger worms are used in compost heaps to digest rotting vegetable material and convert the organic waste into nutrient-rich compost or humus. Worm composting can work in conjunction with the aerobic process to produce a good-quality compost.

Centralised Composting
Centralised composting of organic waste, controlled by local authorities, has increased in the UK throughout the 1990s (see Facts and Figures). This growth has been stimulated by the recycling credits system and landfill tax. Large composting facilities can also be found on industrial premises. Incoming organic matter must be carefully screened and controlled to prevent any contamination. If domestic organic waste is to be composted it needs to be separated at source and will therefore require separate collection facilities.

There are two main central composting options:

The best system for control combines these two processes.

There have been a number of barriers to composting in the UK that have prevented it from fulfilling its potential as an alternative to disposal. The slow development of the sector has been the result of the relatively low price of landfill, doubts over the market for compost and legislative barriers. Contamination of the feedstock can also be an issue, especially for schemes involving the public.

These problems should be reduced by a number of developments which took place in the late 1990s. The imposition of higher landfill tax levels and implementation of the landfill directive will make composting a more economically viable option.

The marketing of peat-free compost will also be aided by the development of Composting Standards by the Composting Association (Materials Recycling Week 1999). In addition, the European Union has devised an eco-label for soil improvers to allow consumers to identify which products have the lowest environmental impact throughout their life cycle. Producers wanting to qualify for the eco-label must meet a range of different criteria. The Composting Association_s The State of Composting in the UK - a blueprint for action will help provide guidance for the development of this sector (Gale 1999).

Anaerobic Digestion
An alternative technology to composting is anaerobic digestion. Anaerobic digestion refers to the biological breakdown of organic material in the absence of oxygen. It is a net energy-producing process as it generates substantial quantities of 'biogas' which consists mainly of methane and carbon dioxide. Biogas is then used as a fuel either directly or to produce electrical energy. By using biogas as a fuel the system is displacing the use of fossil fuels, thereby reducing the emissions of carbon dioxide into the atmosphere.

Although not as commercially developed as composting, anaerobic digestion is increasingly recognised as having a place in modern waste treatment. An anaerobic digesting reactor also has the advantage of needing a lower land requirement than an aerobic composting unit.

There are currently two main types of commercial anaerobic systems on the market. In general terms anaerobic digestion reactors are more expensive than aerobic composting systems. The viability of such a system relies on the price obtained for the biogas fuel.

As with composting schemes, there are problems with the handling of material for anaerobic digesters. Mechanical separation of materials (such as plastic) from the waste is difficult and information about economic and practical issues has not been widely disseminated (Braber 1994). Another potential problem involves the post-treatment of filtrate from the de-watering of slurries from the compost prior to disposal.

Waste Cooking Oil
Waste cooking oil should be treated separately from the treatment processes described above for compost (see Types of Waste A-Z Listing: Oil and Oil Filters). Separate collection facilities exist for caterers and food processors where the oil is recovered, cleaned and blended. (Oil reprocessors do not collect from household sources as the problems of contamination are too difficult to deal with.) The collected oil is sold on for use as an ingredient in animal feed, soap production or in cosmetics. It is important to minimise this waste as the extraction and refining of cooking oil involves the release of volatile organic compounds (VOCs), which has implications for air quality (NHHWF 1998).

DISPOSAL
Organic and food waste should be diverted from landfill and incineration wherever possible due to the environmental impacts described above.

In the past, bonfires have been used by households to burn green waste. Bonfires can be anti-social and the smoke is potentially damaging both to health and to the environment. The potential for composting organic waste largely removes the need for bonfires.

This guide does not cover abattoir waste since it requires specialist handling and is strictly regulated to avoid the spread of disease.

CASE STUDIES

SAINSBURY'S FOOD REDUCTION AND COMPOSTING INITIATIVES
Overall, Sainsbury's supermarkets and Savacentre hypermarkets dispose of approximately 86,500 tonnes of waste a year. Sainsbury's Waste Management team was set up to reduce both the waste bill and the environmental impact of this waste. The team have introduced numerous initiatives to reduce and recycle waste from stores. This case study focuses on some groundbreaking initiatives to tackle food waste.

Reuse: Donation to Charity
As part of a wider Group policy, approximately 80 Sainsbury's stores donate food to charities. This is mainly to Crisis FareShare, a charity for the homeless (see Crisis FareShare Case Study below). Donation trials are currently being run with the Women_s Royal Voluntary Service (WRVS) which runs the Meals on Wheels service. It is anticipated that in 2 to 3 years time all Sainsbury's stores, where feasible, will be linked to charities. In addition, all Sainsbury's depots donate surplus stock to the Grocery Aid charity.

Composting
Fruit, vegetables and salad waste makes up approximately 19% of the waste by weight from supermarkets. This waste can be composted and Sainsbury's has been running composting trials for four years. The work has looked at both the logistical impacts that composting would have on stores as well as at the applications of open-air windrow composting and composting within containers (in vessel).

The main work has been in conjunction with the Organic Resource Agency (ORA). The first phase was part of a research project managed by ORA with funding through Biffaward. This scheme first tested the use of windrows using produce from the Calcot Savacentre hypermarket. Biffa provided the handling and transport link and the produce was collected in domestic wheely bins.

The windrow system developed by ORA was designed for ease of replication on farms. ORA monitored both the quality and quantity of incoming material and the performance of the composting system. The fruit and vegetables were mixed with different combinations of cardboard and straw and the resultant compost was analysed for its nutrient content and tested in growing trials.

The compost was found to make a good soil enhancer. However one store cannot produce the volumes of waste required in order to use the compost for agricultural purposes. The project is now being scaled up to run across the central southern region. Sainsbury's are working on the project with ORA, Biffaward, Waitrose and Peter Kindersley, an independent farmer.

This project will determine the cost of the programme and will look at the performance of a range of different composting systems. This includes the agricultural benefits of compost, the performance of different compostable bags and the viability of including other foodstuffs (e.g. bread) in the three different composting systems.

If composting can be demonstrated to be as cheap or cheaper than landfill, then Sainsbury's will switch to this method as the means of dealing with putrescible waste.

SOURCE: MCKECHNIE 2000

FOOD WASTE REDUCTION: CRISIS FARESHARE
Crisis, which was established in 1967, is a national charity providing practical help for homeless people. Crisis FareShare is one of a number of initiatives run by Crisis. Crisis gives homeless people access to a healthier diet by distributing surplus, high quality and fresh food from food retailers and wholesalers to day-centres and hostels.

Crisis FareShare helps overcome problems associated with poor diet and malnutrition. These are the key problems of homelessness which leave homeless people vulnerable to disease. Hostels and day centres can often be the only source of food for homeless people. Unfortunately it is often the case that these centres cannot afford a regular supply of high-quality fresh food.

On the positive side, stringent company policies often mean that retailers discard food which is still within its use-by-date. There is clearly an opportunity to reduce the amount of wastage (and the disposal bill) for retailers through donation of unwanted produce. Prior to the establishment of the FareShare initiative there were a number of practical barriers for retailers wishing to donate food. These included potential hygiene and health issues as well as logistical and storage problems.

Crisis FareShare is an intermediary linking together the needs of the retailers with the needs of the homeless. The organisation has a network of retailers and wholesalers who regularly donate surplus fresh food. The food is collected in refrigerated vans and taken to a depot where it is sorted and stored. The next day it is distributed to hostels and day centres in accordance with their needs.

A big fear for businesses considering donating food is that it may be resold or that out-of-date produce may be eaten with associated health risks. Crisis FareShare deals with these issues by taking responsibility for the food after it has been collected. All staff are trained in food hygiene and Crisis FareShare is independently audited by The Food Hygiene Bureau. All organisations receiving food have to meet strict criteria to comply with food hygiene legislation. Crisis FareShare audit projects on a regular basis and all out-of-date food is destroyed.

The FareShare pilot scheme began in London in 1994. In addition to the London scheme there is now a national network of franchised schemes running in partnership with local organisations dealing with homelessness. Ten projects will be established by the end of 2000 and currently there are schemes operating in Birmingham, Manchester, Southampton, South Yorkshire, Huddersfield and Edinburgh.

Corporate donors include Sainsbury's, Marks and Spencer and Pret a Manger. Through Crisis FareShare waste reduction can be achieved in a socially responsible manner..

SOURCE: BRADFORD 2000

DISCOVERY COMPOST
The City of Dundee composting scheme, established in 1993, is an excellent example of a local authority approach to centralised composting. It takes putrescible waste from a variety of sources to develop a marketable compost.

The Council offers a green waste kerbside collection to 10,000 households in Dundee. Collections take place for nine months of the year. The service has proven to be very popular and there is a high participation rate, so much so that the Council wish to expand their coverage of the scheme. Over 1,500 tonnes of compostable waste is collected from households each year, with similar amounts collected from civic amenity sites. Green waste from the Council leisure, parks and garden departments is also collected.

The Council also offers separate collections for local businesses as part of their trade waste service. There is a wide range of commercial clients, ranging from distilleries to the Bank of Scotland, which uses the scheme as an environmentally sound way to dispose of used bank notes.

Green waste from all sources is composted using a traditional open windrow system. The main output is Discovery Compost which takes a year to mature. The compost is sold to Angus Horticulture, in Montrose, where it is bagged and distributed to local garden centres and other outlets. Less mature composts are ready in a shorter time and are used for general landscaping within the Council. Other innovative uses of the compost have included bio-remediation of contaminated land in East Lothian.

Discovery Compost is a successful example of a centralised composting scheme. It has reduced the amount of compostable waste going to landfill by 7,000 tonnes per year and provides an environmentally sound alternative to some peat-based products.

SOURCE: OLSEN 2000

FUTURE TRENDS

The Landfill Directive 1999/31 was finalised in 1999. It will have a major impact in the UK where over 80% of waste is disposed to landfill (Weeks 2000). The proposed reduction in the quantity of biodegradable municipal solid waste disposed to landfill will be implemented over three stages:

A 4 year extension to the targets (shown by the numbers in brackets) was granted to the UK in recognition of the UK reliance on landfill. These targets will be re-examined by the EU in 2014. No decision has yet been made as to how progress against targets will be measured.