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New bottles for old: the growth of glass recycling
New bottles for old: the growth of glass recycling Ivan D. Good The recycling of waste material has a long history, as in the shoddy trade in the textile industry, and today appeals to conservationists and environmentalists as well as manufacturers. However, the processes are often complex and their overall economic assessment involves consideration of factors which may not be immediately apparent. As a specific example, this article reviews the development of glass recycling with special reference to British practice during the last ten years.
Despite advanced manufacturing techniques the production of glass bottles and jars still involves a good deal of wastage: as much as 15-20 per cent of production may be rejected as not meeting the required specification. The rejected articles are collected for remelting as cullet (scrap) and in this sense the recycling of waste is a well established trade practice. There is, therefore, nothing new in principle in extending recycling to the recovery of discarded glassware from consumers, but in practice there are considerable difficulties. Leaving aside industrial waste, which is an important source of cullet, a major problem is that relatively small quantities of waste have to be recovered from a very large number of sources, mainly domestic. It is not feasible to recover glass once it has been mixed with general household refuse and an essential requirement is to persuade individuals, in a prosperous convenience-orientated society, voluntarily to separate and make available low-value waste. The solution has been the bottle bank, a system of local collection points to which people can periodically bring their waste bottles and jars for collection. The first such bottle bank in Britain was set up in Oxford in August 1977. Since then quite remarkable progress has been made. There are now 2500 collecting sites located in 850 urban centres: some five million people save at the banks each week and bottles and jars pour in at an average rate of 1000 per minute. Ivan Good, Dip.M.,
M.lnst
Together with material from industrial sources, this corresponds to well over 200 000 tonnes of recycled glass per
annum - equivalent to 12% per cent of all glass waste. This high recovery rate is a tribute both to the social
M., A.M.I.W.M.
Is Commercial Manager of Rockware Reclamation, the recycling division of the Rockware Group of packaging companies. He has been closely connected with the UK bottle bank scheme since 1980 and is currently Chairman of the Glass Manufacturers Federation Environment Committee and a Member of the United Kingdom Reclamation Council. Endeavour, 015&9327/86 ~,;~i~$~~,~y’~
150
New Series, Volume 50.00 + .50. Ltd.
10, No. 3, 1955.
Figure 1 A modern day glass recycling plant needs the capacity thousand tonnes of reclaimed bottles and jars.
to store several
conscience and community spirit of the public and the skill with which the scheme has been promoted. Benefits of glass recycling The demonstrable benefits recycling are fourfold.
of
glass
1. Conservation of raw materials. Clean, crushed cullet is a genuine substitute for the basic ingredients of sand, limestone, and soda ash in the manufacture of glass bottles and jars. In addition, given normal melt loss, there is a positive substitution factor as each tonne of cullet replaces 1.2 tonnes or raw materials. 2. A significant saving of energy. The temperature required to melt cullet in a commercial glass furnace is some 200°C lower than that needed to convert the basic raw materials. So, an additional 10 per cent of cullet in the batch mix can lead to an overall 2 per cent saving on fuel. Put another way, there is a 20 per cent fuel saving on each tonne of cullet remelted back to usable glass. For the glassmaker, there is also the potential of increasing the daily output of a furnace, or possibly extending its life. Against these added values is, however, the possibility of lost production, even furnace damage, from contaminants in cullet. 3. Glass recycling contributes to the protection of our environment. Each tonne of cullet reclaimed represents 1.2 tonnes of raw materials that do not have to be mined, quarried, or processed. Each tonne of cullet recycled is one less for disposal in landfill sites. 4. The fourth benefit is to realise significant savings in the cost of waste collection and disposal. The basis of materials recycling While these benefits are individually and collectively commendable, it is doubtful whether glass recycling would have taken off so dramatically in the UK without the major stimulus of the glass container manufacturing industry itself. Local government subsequently proved to be an invaluable partner. The successful recycling of any material requires: 1. The establishment of an effective end-use market in terms of volume and price. 2. The technology to convert the scrap into a usable raw material. 3. An efficient method of collection/ separation. 4. A general willingness and commitment to achieve. As we have noted a market for clean. crushed cullet was already in existence to absorb waste within the industry. The challenge was to upgrade material reclaimed from the waste stream into a usable raw material.
Experience in the UK and Europe suggested that cullet recovered from the mechanical separation of waste contained too many contaminants to be of commercial value. The quality of material collected by early separation at source schemes in Switzerland and Austria looked to provide a more viable route. So, while the Glass Manufacturers Federation instigated four trial bottle bank schemes in the UK, its members actively researched the technical processing of large volumes of reclaimed bottles and jars. Bottle banks can in fact generate very high quality cullet, both in terms of separate glasses of different colours (basically white, green, amber) and incidence of contamination. The processing plants can, therefore, concentrate on removing materials associated with retail glass packs: closures, capsules, and labels (figure 1). After two years of bottle bank collection trials, the British glass industry committed itself, in 1979, to a f5 million investment programme to promote the large-scale reclamation of glass and develop the necessary processing plants. The economics of collection proved viable and the scheme has not looked back since. Stable market From the outset, the industry set out to establish a stable market for cullet and this has probably been the most important commercial factor behind the dynamic growth of collection schemes. A constant demand can be guaranteed provided the cullet is clean and colour separated. In Switzerland, glass furnaces are regularly charged with 90 per cent reclaimed material. The requirement for separation according to colour simply reflects the fact that manufacturers’ sales average 75 per cent white flint (clear), 13 per cent green, and 12 per cent amber (brown). The industry can use some mixed cullet but only in its green furnaces where sensitivity to wrong colour is of less consequence. Provided colour separation can be maintained, it is unrealistic to think that the demand for cullet will ever be completely satisfied. By linking the price paid for cullet to the value of the substituted raw materials, the industry has been able to guarantee minimum prices for reclaimed material. Since different qualities of raw material are used for various colours. it is normal for four cullet prices to be quoted - for white flint, green, amber, and mixed respectively - and today, these range downwards from f3&f22 per tonne after allowing for the costs of processing. It is uncommon for glass makers to quote prices for processed, refined
cullet in Europe. Typically, the treatment plant is owned by the glass company or operated by an approved contractor so that the tightest possible control can be exercised over cullet quality.
Economics of collection Everyone agrees that recycling shouid be ‘economic’, but difficulty arises in trying to find a common definition of the word. For local authorities involved, in the collection and disposal of refuse, the total waste management equation can be set out as follows:
t Average cost per tonne of collection 22.00 Average cost per tonne of disposal 8.00 Average sales value of cullet 25.00 Less bulk haulage to recycling plant (5.00) 50.00 In Europe, where contracted services are often the norm, a recycling scheme costing, say, g45.00 per tonne would be viewed as producing a direct benefit. Traditionally, in the UK, many have looked to recover all costs within the sales revenue of the recycled material and only now are the broader savings being taken into account. Effective recycling schemes take several years to develop and it is axiomatic that real savings for collection authorities (in Britain, the district councils) tend to come only with a large scale operation. For disposal authorities (the county councils) every tonne separated for recycling is one tonne less for haulage/transfer/ incineration/landfill. At the outset, many thought that bottle banking would be appropriate only for densely populated urban areas with high refuse collection and disposal costs. The progress of glass recycling was in fact led by the Shire counties and districts. The mobility of council officers with direct experience of running schemes is ensuring the continued spread of bottle banks into the more rural areas. The most successful schemes are often those where both tiers of local government have worked closely together. In other areas, district councils have worked alone or in partnership with neighbouring authorities to demonstrate what can be achieved with a high density of sites and the right level of enthusiasm, application, and good local publicity. In support of this the glass industry has made significant investments to ensure support for all bottle bank operators. 151
Today, in Bracknell, Cambridge, Colwyn, Chiltern, Kingswood, Reading, Richmond-upon-thames, Roxburgh, and elsewhere, bottle banks are removing between 2540 per cent of glass form the waste stream. The scale of such operations means not only full cost recovery and profits but often additional identifiable benefits including: 1. Savings on refuse collection costs. 2. Lower accident and spillage complaints (associated with the use of plastic sacks) 3. Less abrasive wear on compaction vehicles/equipment 4. Extension of landfill life. In Berkshire, a county of 700 000 population with high disposal costs (15.62 per tonne) 3300 tonnes of glass were recycled by the six districts in 1984 alone. In the same year, the more rural Devon County Council (disposal costs f4.67 per tonne) extended bottle banks to 12 of its 14 districts, reflecting not only an interest in savings but the broader environmental pressures on landfill sites. The benefits of bottle banks and other reclamation schemes are now generally accepted and the large urban authorities are probably leading the drive for increased recycling and innovative disposal. With increased waste incineration and the development of Refuse Derived Fuel plants, separation of the solid waste fraction has become more significant, giving further importance to bottle bank schemes. Types of collection
scheme
Bottle banking in the UK started with the use of specially converted metal ‘skips’. The normal capacity is 13 cubic metres, holding an average 3% tonnes of cullet. This type of scheme accounts for roughly half of the cullet collected and will continue to be the most popular method in many areas (figure 2). For such a scheme, the operator needs to: 1. Obtain by purchase, rent, or sponsorship, an appropriate number of large banks. 2. Supply a regular bank emptying service, using a suitable skip-handling vehicle. 3. Provide three concrete storage bays - one for each colour - approximately 8 x 8 metres fronted by a concrete apron. 4. Have accessto a mechanical shovel for bulk vehicle loading and cullet marshalling. The banks are emptied, one compartment at a time, into the appropriate colour bay. When 20 tonnes or 152
more of any one colour has been accumulated, it is bulk hauled to the Glass Recycling Centre. Companies like Rockware Reclamation often organise such transport using competitive back-loading arrangements. The alternative system of collection utilises modular bottle banks which are emptied on site (figure 3). A site consists of at least three modular banks, one for each colour of glass. The average cullet capacity of a bank is Y4 tonne. The banks are emptied by a tipper vehicle fitted with a crane, enabling them to be hoisted above the vehicle to discharge the contents. The vehicle can be partitioned to collect one, two, or three colours at a time. A number of different types of modular banks are available. The most popular are the GRP (fibreglass) or polyethylene ‘Igloo’, approximately 1.8 metres in diameter, and the metre square metal bank designed by Rockware. Cost of collection
The large bank scheme is usually the easiest and most profitable to set up and operate. It is applicable to most
TABLE
1
ROCKWARE
areas and normally requires cullet collection from four -or five sites to justify expenditure on a storage depot. The scheme can be extended to accommodate all suitable sites within an economic distance. It is common practice for neighbouring authorities to share storage facilities. The modular bank system requires more specialist organisation and transport systems. If a suitable collection vehicle is not available locally on a part-time basis, then 30 to 40 bottle banks sites would be needed to support a reliable collection service, costing some f1200 per week. This requirement calls for co-operation between neighbouring districts and/or counties, possibly in association with a private transport contractor. Compared with large banks, modular systems of collection offer the facility to: 1. Extend glass recycling into areas which would not otherwise be viable. 2. Increase public response through a greater density of sites. 3. Generate cullet collection from commercial and industrial premises. To check the viability of a proposed
RECLAMATION: OUTLINE ECONOMIC BOTTLE BANK SCHEME
6 large bottle banks collecting tonnes from 150 000 population
OF A
an average 1% tonnes/week = 468 tonnes/year = 3.12 kg/head = 12%% redemption rate
CAPITAL EXPENDITURE Bottle Bank Skips 6 banks @ f850 = f5,lOO; 26% taken as the annual repayment over 5 years including interest and amortised over 468 tonnes Refuse Bins 6 recepticles @ f40 = f240; charged over 5 years as bottle banks Storage Bays 3 concrete based storage bays = f10.000; 15% taken as the annual repayment over 15 years including interest and amortised over 468 tonnes OPERATING COSTS Skip Emptying f24 per movement of 3% tonnes Skip Maintenance 6 banks @ f50 per annum = f300 Site Tidying/Cleansing 6 hours @ f3 = f18 per week Mechanical Shovel Load 20 tonnes in one hour Supervision/Administration Taken as 5% on all aforegoing costs
TOTAL COSTS REVENUE: collected PROFIT
EVALUATION
f per tonne
2.83
0.13
3.21
6.86 0.64 2.00 1.oo 0.83
f17.50 price per tonne
468
f20.00 f 2.50
and counties can provide great benefits. For example, in Hampshire the County Council provides storage bays and loading facilities at nominal cost for district authorities to run in their full bottle bank containers. Capital investment in bottle banks can be avoided through sponsorship. Many local authorities have managed to find sponsors for some, if not all, of their bottle banks. The sponsor, who can be anyone from a major High Street bank to a small local company, gets his name or product before a large sector of the public through a permanent message on the bank. He also gains the spin-off benefit of being seen to have a responsible attitude towards environmental matters and, as is often the case, by being associated with raising money for charity. Bottle
Figure 2 How it all began. A 14 cubic yard bottle bank with 3 coiour compartments photographed at a promotional event in Wellingborough, UK, with a 20 tonne bulk tipper.
bottle bank scheme, it is necessary to take into account full details of income and expenditure. The income side is simply the multiple of the estimated tonnage collected at the current cullet value. The expenditure figures start with capital, which covers skip purchase (if applicable), storage bay construction, litter bins, and the provision of street signs. Capital should be amortised over the authority’s standard period (not
less than five years) at the current interest rates, producing a resultant annual cost. To this figure must be added operating costs, which include local emptying. site tidying, a mechanical shovel, and any management/ supervisory charges. A typical balance sheet prepared by Rockware Reclamation is shown in Table 1. Whatever the area and whichever the scheme, co-operation and collaboration between district authorities
Quality
Figure 3
Igloo bottle bank being emptied
on site in London
Borough
of Ealing
bank siting
Correct siting is vital to a scheme’s success. If the bank is to be filled rapidly it must either be in an area of dense population or in a place visited regularly by a large number of people. Ideal sites in a particular town or area can be selected only by examination but the best ones are certainly busy car parks attached to supermarkets, or busy shopping areas. In Britain, most of the major grocery retailers have a policy of permitting the siting of banks on their private car parks. The out-of-town shopping precinct is another good position. The number of bottle banks in a region therefore depends on the availability of suitable sites; on the type of shopping and housing areas; on the population; and on the type of scheme operated. As an approximate guide. a successful site should generate 1% tonnes of cullet per week or 5000 bottles and jars. Generally speaking, the relatively low value of cullet makes it uneconomic to collect glass direct from individual households. However, commercial catering premises such as hotels, wine bars, and restaurants can produce sufficient numbers of empty glass containers to justify individual collection from the premises. of bottle
bank cullet
Limiting the diameter of access holes to a maximum of 15cm has proved in practice to limit sufficiently the amount of extraneous materials and general rubbish getting mixed with the cullet. In most cases, it would seem that if the general public are sufficiently motivated to take their waste bottles and jars to a bottle bank, then they are prepared to use the facility properly. This includes an exceptionally high degree of colour separation. However, given that the material 153
being purchased by the recycling plant is known to contain some contamination, there is really no scientific or practical method of quality control as the cullet is delivered. Indeed, an attempt to enforce an inflexible standard at this point could easily deter many collectors. The typical procedure is purely empirical. Each bulk load of cullet is inspected as it is discharged in front of the appropriate storage bay. The inspector is essentially looking for contamination not associated with normal bottle bank operations. The predictable contaminants are paper labels, plastic and metal closures, and metal foils. It is not unusual to spot the occasional can, plastic bottle, and supermarket carrier bag. These are non-critical faults which the processing system is designed to remove. The critical contaminants are inorganic materials - stones, gravel, tarmacadam, bricks, etc. - and non-ferrous metals which could cause severe damage to furnaces as well as affecting the quality of the finished glass product. Such problems tend to be few and far between and generally only originate from poor house keeping at the storage depot or the use of an unclean delivery vehicle. Recycling
plant
The processing cycle starts, therefore, with delivery of the cullet to the recycling centre where it is weighed, inspected and stored in bunkers so that the three colours do not get mixed up. The glass is fed into the plant on conveyor belts, one colour at a time.
Waste glass kullet) fed in thrwgh looding tqp~ by mechanical shovel
Inspectors carefully check for large foreign objects and contaminants such as plastic bottles or pieces of brick, and also for wrong colour. A battery of TABLE 2 ROCKWARE RECLAMATION: SPECIFICATION FOR PROCESSED CULLET Per Cent Content 0.05 0.01 coloured 0.005 flint 0.01 Metals Non-Magnetic 0.30 Organic
Maximum Material Stone/Ceramics Metals Magnetic
Glass Colour Green in Flint Amber in Flint Flint in Green Amber in Green Green in Amber Flint in Amber
TABLE 3
traps remainhg wosie wchoSCOPSdppW
4 Remove waste
154
glass recycling
47 120 25 540 884 161 6 428 230 23 124 127 2 715
Mugnet remaves any metal oQect5
Waste material
centre. How it works.
GLASS RECYCLING - 1984
Tonnes recycled
Austria Belgium Denmark France Germany Great Britain Ireland Italy Netherlands Portugal Spain Switzerland TOTAL
Uncrushed cutlet
Rockware
EUROPEAN
Country
Crushed cull&
Figure 4
Per Cent 0.5 2.0 10.0 15.0 5.0 10.0
mechanical processes then takes over; impact crushers which release metal and plastic closures and rings from the bottles and jars, overband magnets which take out ferrous metal, and vacuum extraction systems which remove aluminium caps, lead foils, plastic, and paper. Figure 4 outlines the operation of the Rockware Glass Recycling Centre in Knottingley, West Yorkshire. Built in 1979 at a cost of f500 000, this sophisticated plant processescullet at a rate of 14 tonnes per hour, normally 16 hours per day, up to 7 days per week. The processing plant is responsible for producing raw material for glass manufacture against specific quality specifications (Table 2). In practice, the most difficult control to meet is that of non-ferrous metal inclusions - aluminium and lead. Aluminium is used for a variety of
000 000 000 000 000 000 000 000 000 000 000 000 000
Proportion of national glass consumption (%) 30 36 20 25 31 9 7 24 53 10 13 45
glass container closures, including the pilferproof type which leaves a ring around the neck of the bottle when the cap is unscrewed. With careful adjustment of the crusher it is possible to smash the glass containers without shredding or deforming the aluminium rings and with simple flattening of the caps. The material is then passed over vibrating sieving screens with holes of between 15 mm-25 mm diameter. Most of the cullet falls through, allowing vacuum hoods to draw up the aluminium along with particles of paper and plastic. Oversize material will pass over the sieving screens permitting manual sorting on a secondary inspection belt before being sent for re-crushing. Lead foils can be removed in a similar way to aluminium, but the problem is greater due to the density of the metal and its tendency to roll into balls during and after the crushing
3
E 3c2 s .5I .I 1977
‘78
‘79
‘80
‘81
‘82
83
Figure 5 Total glass recycled (excluding manufacturers’ cullet) in Belgium, Denmark, France, Germany, Great Britain, Eire, Holland and Italy. Since 1981 includes Austria and Switzerland. 1983 and 1984 include Spain and Portugal.
84
process. With increased wine consumption in the UK, Rockware’s plant at Knottingley is now installing an additional inspection belt on processed cullet to remove manually remaining lead and aluminium contaminants. While computerised controls and modern processing techniques are applied to today’s glass recycling plants, it can be seen that the system is highly reliant on the human element. In fact, it is fair to say that the success of the glass recycling programme marks a positive return for ‘low technology’ (Table 3; figure 5). The bottle bank scheme has perhaps
succeeded because of its very simplicity, from which everyone benefits. The general public have responded to an environmentally sensible campaign in which participation is easy and convenient. Profits are often donated to local charitable causes. Local authorities are able to achieve genuine savings in the collection and disposal of refuse. Industry benefits from fuel savings in the production of new glass bottles and jars. Overall, the nation is rewarded by the conservation of natural resources and the education of the public to have a better and broader understanding of the environment in which we all live.
155
Despite advanced manufacturing techniques the production of glass bottles and jars still involves a good deal of wastage: as much as 15-20 per cent of production may be rejected as not meeting the required specification. The rejected articles are collected for remelting as cullet (scrap) and in this sense the recycling of waste is a well established trade practice. There is, therefore, nothing new in principle in extending recycling to the recovery of discarded glassware from consumers, but in practice there are considerable difficulties. Leaving aside industrial waste, which is an important source of cullet, a major problem is that relatively small quantities of waste have to be recovered from a very large number of sources, mainly domestic. It is not feasible to recover glass once it has been mixed with general household refuse and an essential requirement is to persuade individuals, in a prosperous convenience-orientated society, voluntarily to separate and make available low-value waste. The solution has been the bottle bank, a system of local collection points to which people can periodically bring their waste bottles and jars for collection. The first such bottle bank in Britain was set up in Oxford in August 1977. Since then quite remarkable progress has been made. There are now 2500 collecting sites located in 850 urban centres: some five million people save at the banks each week and bottles and jars pour in at an average rate of 1000 per minute. Ivan Good, Dip.M.,
M.lnst
Together with material from industrial sources, this corresponds to well over 200 000 tonnes of recycled glass per
annum - equivalent to 12% per cent of all glass waste. This high recovery rate is a tribute both to the social
M., A.M.I.W.M.
Is Commercial Manager of Rockware Reclamation, the recycling division of the Rockware Group of packaging companies. He has been closely connected with the UK bottle bank scheme since 1980 and is currently Chairman of the Glass Manufacturers Federation Environment Committee and a Member of the United Kingdom Reclamation Council. Endeavour, 015&9327/86 ~,;~i~$~~,~y’~
150
New Series, Volume 50.00 + .50. Ltd.
10, No. 3, 1955.
Figure 1 A modern day glass recycling plant needs the capacity thousand tonnes of reclaimed bottles and jars.
to store several
conscience and community spirit of the public and the skill with which the scheme has been promoted. Benefits of glass recycling The demonstrable benefits recycling are fourfold.
of
glass
1. Conservation of raw materials. Clean, crushed cullet is a genuine substitute for the basic ingredients of sand, limestone, and soda ash in the manufacture of glass bottles and jars. In addition, given normal melt loss, there is a positive substitution factor as each tonne of cullet replaces 1.2 tonnes or raw materials. 2. A significant saving of energy. The temperature required to melt cullet in a commercial glass furnace is some 200°C lower than that needed to convert the basic raw materials. So, an additional 10 per cent of cullet in the batch mix can lead to an overall 2 per cent saving on fuel. Put another way, there is a 20 per cent fuel saving on each tonne of cullet remelted back to usable glass. For the glassmaker, there is also the potential of increasing the daily output of a furnace, or possibly extending its life. Against these added values is, however, the possibility of lost production, even furnace damage, from contaminants in cullet. 3. Glass recycling contributes to the protection of our environment. Each tonne of cullet reclaimed represents 1.2 tonnes of raw materials that do not have to be mined, quarried, or processed. Each tonne of cullet recycled is one less for disposal in landfill sites. 4. The fourth benefit is to realise significant savings in the cost of waste collection and disposal. The basis of materials recycling While these benefits are individually and collectively commendable, it is doubtful whether glass recycling would have taken off so dramatically in the UK without the major stimulus of the glass container manufacturing industry itself. Local government subsequently proved to be an invaluable partner. The successful recycling of any material requires: 1. The establishment of an effective end-use market in terms of volume and price. 2. The technology to convert the scrap into a usable raw material. 3. An efficient method of collection/ separation. 4. A general willingness and commitment to achieve. As we have noted a market for clean. crushed cullet was already in existence to absorb waste within the industry. The challenge was to upgrade material reclaimed from the waste stream into a usable raw material.
Experience in the UK and Europe suggested that cullet recovered from the mechanical separation of waste contained too many contaminants to be of commercial value. The quality of material collected by early separation at source schemes in Switzerland and Austria looked to provide a more viable route. So, while the Glass Manufacturers Federation instigated four trial bottle bank schemes in the UK, its members actively researched the technical processing of large volumes of reclaimed bottles and jars. Bottle banks can in fact generate very high quality cullet, both in terms of separate glasses of different colours (basically white, green, amber) and incidence of contamination. The processing plants can, therefore, concentrate on removing materials associated with retail glass packs: closures, capsules, and labels (figure 1). After two years of bottle bank collection trials, the British glass industry committed itself, in 1979, to a f5 million investment programme to promote the large-scale reclamation of glass and develop the necessary processing plants. The economics of collection proved viable and the scheme has not looked back since. Stable market From the outset, the industry set out to establish a stable market for cullet and this has probably been the most important commercial factor behind the dynamic growth of collection schemes. A constant demand can be guaranteed provided the cullet is clean and colour separated. In Switzerland, glass furnaces are regularly charged with 90 per cent reclaimed material. The requirement for separation according to colour simply reflects the fact that manufacturers’ sales average 75 per cent white flint (clear), 13 per cent green, and 12 per cent amber (brown). The industry can use some mixed cullet but only in its green furnaces where sensitivity to wrong colour is of less consequence. Provided colour separation can be maintained, it is unrealistic to think that the demand for cullet will ever be completely satisfied. By linking the price paid for cullet to the value of the substituted raw materials, the industry has been able to guarantee minimum prices for reclaimed material. Since different qualities of raw material are used for various colours. it is normal for four cullet prices to be quoted - for white flint, green, amber, and mixed respectively - and today, these range downwards from f3&f22 per tonne after allowing for the costs of processing. It is uncommon for glass makers to quote prices for processed, refined
cullet in Europe. Typically, the treatment plant is owned by the glass company or operated by an approved contractor so that the tightest possible control can be exercised over cullet quality.
Economics of collection Everyone agrees that recycling shouid be ‘economic’, but difficulty arises in trying to find a common definition of the word. For local authorities involved, in the collection and disposal of refuse, the total waste management equation can be set out as follows:
t Average cost per tonne of collection 22.00 Average cost per tonne of disposal 8.00 Average sales value of cullet 25.00 Less bulk haulage to recycling plant (5.00) 50.00 In Europe, where contracted services are often the norm, a recycling scheme costing, say, g45.00 per tonne would be viewed as producing a direct benefit. Traditionally, in the UK, many have looked to recover all costs within the sales revenue of the recycled material and only now are the broader savings being taken into account. Effective recycling schemes take several years to develop and it is axiomatic that real savings for collection authorities (in Britain, the district councils) tend to come only with a large scale operation. For disposal authorities (the county councils) every tonne separated for recycling is one tonne less for haulage/transfer/ incineration/landfill. At the outset, many thought that bottle banking would be appropriate only for densely populated urban areas with high refuse collection and disposal costs. The progress of glass recycling was in fact led by the Shire counties and districts. The mobility of council officers with direct experience of running schemes is ensuring the continued spread of bottle banks into the more rural areas. The most successful schemes are often those where both tiers of local government have worked closely together. In other areas, district councils have worked alone or in partnership with neighbouring authorities to demonstrate what can be achieved with a high density of sites and the right level of enthusiasm, application, and good local publicity. In support of this the glass industry has made significant investments to ensure support for all bottle bank operators. 151
Today, in Bracknell, Cambridge, Colwyn, Chiltern, Kingswood, Reading, Richmond-upon-thames, Roxburgh, and elsewhere, bottle banks are removing between 2540 per cent of glass form the waste stream. The scale of such operations means not only full cost recovery and profits but often additional identifiable benefits including: 1. Savings on refuse collection costs. 2. Lower accident and spillage complaints (associated with the use of plastic sacks) 3. Less abrasive wear on compaction vehicles/equipment 4. Extension of landfill life. In Berkshire, a county of 700 000 population with high disposal costs (15.62 per tonne) 3300 tonnes of glass were recycled by the six districts in 1984 alone. In the same year, the more rural Devon County Council (disposal costs f4.67 per tonne) extended bottle banks to 12 of its 14 districts, reflecting not only an interest in savings but the broader environmental pressures on landfill sites. The benefits of bottle banks and other reclamation schemes are now generally accepted and the large urban authorities are probably leading the drive for increased recycling and innovative disposal. With increased waste incineration and the development of Refuse Derived Fuel plants, separation of the solid waste fraction has become more significant, giving further importance to bottle bank schemes. Types of collection
scheme
Bottle banking in the UK started with the use of specially converted metal ‘skips’. The normal capacity is 13 cubic metres, holding an average 3% tonnes of cullet. This type of scheme accounts for roughly half of the cullet collected and will continue to be the most popular method in many areas (figure 2). For such a scheme, the operator needs to: 1. Obtain by purchase, rent, or sponsorship, an appropriate number of large banks. 2. Supply a regular bank emptying service, using a suitable skip-handling vehicle. 3. Provide three concrete storage bays - one for each colour - approximately 8 x 8 metres fronted by a concrete apron. 4. Have accessto a mechanical shovel for bulk vehicle loading and cullet marshalling. The banks are emptied, one compartment at a time, into the appropriate colour bay. When 20 tonnes or 152
more of any one colour has been accumulated, it is bulk hauled to the Glass Recycling Centre. Companies like Rockware Reclamation often organise such transport using competitive back-loading arrangements. The alternative system of collection utilises modular bottle banks which are emptied on site (figure 3). A site consists of at least three modular banks, one for each colour of glass. The average cullet capacity of a bank is Y4 tonne. The banks are emptied by a tipper vehicle fitted with a crane, enabling them to be hoisted above the vehicle to discharge the contents. The vehicle can be partitioned to collect one, two, or three colours at a time. A number of different types of modular banks are available. The most popular are the GRP (fibreglass) or polyethylene ‘Igloo’, approximately 1.8 metres in diameter, and the metre square metal bank designed by Rockware. Cost of collection
The large bank scheme is usually the easiest and most profitable to set up and operate. It is applicable to most
TABLE
1
ROCKWARE
areas and normally requires cullet collection from four -or five sites to justify expenditure on a storage depot. The scheme can be extended to accommodate all suitable sites within an economic distance. It is common practice for neighbouring authorities to share storage facilities. The modular bank system requires more specialist organisation and transport systems. If a suitable collection vehicle is not available locally on a part-time basis, then 30 to 40 bottle banks sites would be needed to support a reliable collection service, costing some f1200 per week. This requirement calls for co-operation between neighbouring districts and/or counties, possibly in association with a private transport contractor. Compared with large banks, modular systems of collection offer the facility to: 1. Extend glass recycling into areas which would not otherwise be viable. 2. Increase public response through a greater density of sites. 3. Generate cullet collection from commercial and industrial premises. To check the viability of a proposed
RECLAMATION: OUTLINE ECONOMIC BOTTLE BANK SCHEME
6 large bottle banks collecting tonnes from 150 000 population
OF A
an average 1% tonnes/week = 468 tonnes/year = 3.12 kg/head = 12%% redemption rate
CAPITAL EXPENDITURE Bottle Bank Skips 6 banks @ f850 = f5,lOO; 26% taken as the annual repayment over 5 years including interest and amortised over 468 tonnes Refuse Bins 6 recepticles @ f40 = f240; charged over 5 years as bottle banks Storage Bays 3 concrete based storage bays = f10.000; 15% taken as the annual repayment over 15 years including interest and amortised over 468 tonnes OPERATING COSTS Skip Emptying f24 per movement of 3% tonnes Skip Maintenance 6 banks @ f50 per annum = f300 Site Tidying/Cleansing 6 hours @ f3 = f18 per week Mechanical Shovel Load 20 tonnes in one hour Supervision/Administration Taken as 5% on all aforegoing costs
TOTAL COSTS REVENUE: collected PROFIT
EVALUATION
f per tonne
2.83
0.13
3.21
6.86 0.64 2.00 1.oo 0.83
f17.50 price per tonne
468
f20.00 f 2.50
and counties can provide great benefits. For example, in Hampshire the County Council provides storage bays and loading facilities at nominal cost for district authorities to run in their full bottle bank containers. Capital investment in bottle banks can be avoided through sponsorship. Many local authorities have managed to find sponsors for some, if not all, of their bottle banks. The sponsor, who can be anyone from a major High Street bank to a small local company, gets his name or product before a large sector of the public through a permanent message on the bank. He also gains the spin-off benefit of being seen to have a responsible attitude towards environmental matters and, as is often the case, by being associated with raising money for charity. Bottle
Figure 2 How it all began. A 14 cubic yard bottle bank with 3 coiour compartments photographed at a promotional event in Wellingborough, UK, with a 20 tonne bulk tipper.
bottle bank scheme, it is necessary to take into account full details of income and expenditure. The income side is simply the multiple of the estimated tonnage collected at the current cullet value. The expenditure figures start with capital, which covers skip purchase (if applicable), storage bay construction, litter bins, and the provision of street signs. Capital should be amortised over the authority’s standard period (not
less than five years) at the current interest rates, producing a resultant annual cost. To this figure must be added operating costs, which include local emptying. site tidying, a mechanical shovel, and any management/ supervisory charges. A typical balance sheet prepared by Rockware Reclamation is shown in Table 1. Whatever the area and whichever the scheme, co-operation and collaboration between district authorities
Quality
Figure 3
Igloo bottle bank being emptied
on site in London
Borough
of Ealing
bank siting
Correct siting is vital to a scheme’s success. If the bank is to be filled rapidly it must either be in an area of dense population or in a place visited regularly by a large number of people. Ideal sites in a particular town or area can be selected only by examination but the best ones are certainly busy car parks attached to supermarkets, or busy shopping areas. In Britain, most of the major grocery retailers have a policy of permitting the siting of banks on their private car parks. The out-of-town shopping precinct is another good position. The number of bottle banks in a region therefore depends on the availability of suitable sites; on the type of shopping and housing areas; on the population; and on the type of scheme operated. As an approximate guide. a successful site should generate 1% tonnes of cullet per week or 5000 bottles and jars. Generally speaking, the relatively low value of cullet makes it uneconomic to collect glass direct from individual households. However, commercial catering premises such as hotels, wine bars, and restaurants can produce sufficient numbers of empty glass containers to justify individual collection from the premises. of bottle
bank cullet
Limiting the diameter of access holes to a maximum of 15cm has proved in practice to limit sufficiently the amount of extraneous materials and general rubbish getting mixed with the cullet. In most cases, it would seem that if the general public are sufficiently motivated to take their waste bottles and jars to a bottle bank, then they are prepared to use the facility properly. This includes an exceptionally high degree of colour separation. However, given that the material 153
being purchased by the recycling plant is known to contain some contamination, there is really no scientific or practical method of quality control as the cullet is delivered. Indeed, an attempt to enforce an inflexible standard at this point could easily deter many collectors. The typical procedure is purely empirical. Each bulk load of cullet is inspected as it is discharged in front of the appropriate storage bay. The inspector is essentially looking for contamination not associated with normal bottle bank operations. The predictable contaminants are paper labels, plastic and metal closures, and metal foils. It is not unusual to spot the occasional can, plastic bottle, and supermarket carrier bag. These are non-critical faults which the processing system is designed to remove. The critical contaminants are inorganic materials - stones, gravel, tarmacadam, bricks, etc. - and non-ferrous metals which could cause severe damage to furnaces as well as affecting the quality of the finished glass product. Such problems tend to be few and far between and generally only originate from poor house keeping at the storage depot or the use of an unclean delivery vehicle. Recycling
plant
The processing cycle starts, therefore, with delivery of the cullet to the recycling centre where it is weighed, inspected and stored in bunkers so that the three colours do not get mixed up. The glass is fed into the plant on conveyor belts, one colour at a time.
Waste glass kullet) fed in thrwgh looding tqp~ by mechanical shovel
Inspectors carefully check for large foreign objects and contaminants such as plastic bottles or pieces of brick, and also for wrong colour. A battery of TABLE 2 ROCKWARE RECLAMATION: SPECIFICATION FOR PROCESSED CULLET Per Cent Content 0.05 0.01 coloured 0.005 flint 0.01 Metals Non-Magnetic 0.30 Organic
Maximum Material Stone/Ceramics Metals Magnetic
Glass Colour Green in Flint Amber in Flint Flint in Green Amber in Green Green in Amber Flint in Amber
TABLE 3
traps remainhg wosie wchoSCOPSdppW
4 Remove waste
154
glass recycling
47 120 25 540 884 161 6 428 230 23 124 127 2 715
Mugnet remaves any metal oQect5
Waste material
centre. How it works.
GLASS RECYCLING - 1984
Tonnes recycled
Austria Belgium Denmark France Germany Great Britain Ireland Italy Netherlands Portugal Spain Switzerland TOTAL
Uncrushed cutlet
Rockware
EUROPEAN
Country
Crushed cull&
Figure 4
Per Cent 0.5 2.0 10.0 15.0 5.0 10.0
mechanical processes then takes over; impact crushers which release metal and plastic closures and rings from the bottles and jars, overband magnets which take out ferrous metal, and vacuum extraction systems which remove aluminium caps, lead foils, plastic, and paper. Figure 4 outlines the operation of the Rockware Glass Recycling Centre in Knottingley, West Yorkshire. Built in 1979 at a cost of f500 000, this sophisticated plant processescullet at a rate of 14 tonnes per hour, normally 16 hours per day, up to 7 days per week. The processing plant is responsible for producing raw material for glass manufacture against specific quality specifications (Table 2). In practice, the most difficult control to meet is that of non-ferrous metal inclusions - aluminium and lead. Aluminium is used for a variety of
000 000 000 000 000 000 000 000 000 000 000 000 000
Proportion of national glass consumption (%) 30 36 20 25 31 9 7 24 53 10 13 45
glass container closures, including the pilferproof type which leaves a ring around the neck of the bottle when the cap is unscrewed. With careful adjustment of the crusher it is possible to smash the glass containers without shredding or deforming the aluminium rings and with simple flattening of the caps. The material is then passed over vibrating sieving screens with holes of between 15 mm-25 mm diameter. Most of the cullet falls through, allowing vacuum hoods to draw up the aluminium along with particles of paper and plastic. Oversize material will pass over the sieving screens permitting manual sorting on a secondary inspection belt before being sent for re-crushing. Lead foils can be removed in a similar way to aluminium, but the problem is greater due to the density of the metal and its tendency to roll into balls during and after the crushing
3
E 3c2 s .5I .I 1977
‘78
‘79
‘80
‘81
‘82
83
Figure 5 Total glass recycled (excluding manufacturers’ cullet) in Belgium, Denmark, France, Germany, Great Britain, Eire, Holland and Italy. Since 1981 includes Austria and Switzerland. 1983 and 1984 include Spain and Portugal.
84
process. With increased wine consumption in the UK, Rockware’s plant at Knottingley is now installing an additional inspection belt on processed cullet to remove manually remaining lead and aluminium contaminants. While computerised controls and modern processing techniques are applied to today’s glass recycling plants, it can be seen that the system is highly reliant on the human element. In fact, it is fair to say that the success of the glass recycling programme marks a positive return for ‘low technology’ (Table 3; figure 5). The bottle bank scheme has perhaps
succeeded because of its very simplicity, from which everyone benefits. The general public have responded to an environmentally sensible campaign in which participation is easy and convenient. Profits are often donated to local charitable causes. Local authorities are able to achieve genuine savings in the collection and disposal of refuse. Industry benefits from fuel savings in the production of new glass bottles and jars. Overall, the nation is rewarded by the conservation of natural resources and the education of the public to have a better and broader understanding of the environment in which we all live.
155