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MANAGEMENT OF WATER FLOWS |
RINGKØBING CASE STUDY - THE MANAGEMENT OF BIODEGRADABLE WASTE Ulrik Reeh, Danish Forest and Landscape Research Institute
The municipality of Ringkoebing is well known in Denmark for its pioneering contribution to developing a more sustainable approach to the management of household waste; it has established the first full scale system for dealing with biodegradable household waste in Denmark. This has been achieved by offering home composting as the only way to handle biodegradable household waste from "single family" houses in Ringkoebing. The municipality has focused on the biodegradable component of household waste, which is characterized by being the largest single component of household waste and the only one that could be processed and utilized at the source of generation. Biological processing of the biodegradable component, one way or the other, is essential in all towns if the recycling target of 50% of waste recycled, set by the Danish government, is to be met by the year 2000.
Domestic biodegradable waste The new waste handling system was introduced in the Autumn of 1991. An important element of the project was the simultaneous introduction of the collection of the residual burnable component, although this is now collected only every second week instead of weekly. In addition to stimulating use of the compost bin, this system aims to promote the recycling of paper and glass which has to be put in containers within each housing group or collected every second month by scouts or other volunteer groups. The introduction of the new system was accompanied by a green hot line. Although this line was managed by a non-specialist member of the municipal administration with little biological knowledge, it made an active contribution to the public relations exercise aimed at getting the new system underway. After the first phase of the new system was completed, about 3,400 of the "single family" houses had received a compost bin. As at September 1998 nearly 4,500 bins have been distributed by the municipality. This amounts to approximately 77% of those dwellings in Ringkoebing with their own gardens. It is, however, very difficult to estimate the amount of waste actually being home composted. A survey of the system after the first two years estimated an average amount per household per week of 3.9 kg being composted; this declined to 1.8 kg in 1992. No more estimates of the amounts of waste being home composted were carried out until the present survey. From the beginning of 1997 households composting waste received a yearly discount of 350 Dkr. on the charge to the household for waste disposal. However, a survey in late 1997 among 322 of households that had recently joined the scheme showed that between 15%-18% of these had never used the compost bin. Consequently some of them lost their reduced fee. Others obtained a special exemption: for example, if they could prove that they carried out home composting in another way or that they produced very little biodegradable waste, perhaps because they participated in the municipal food distribution system for elderly people. The percentage of unused bins in the1997 survey mirrors the result of the survey in 1991-92 which indicated that 14%-20% were not used and 7%-10% only made small use of the compost bins. In addition, a major change has been that 462 of the households (of which 337 live in apartments which were not allocated home composters anyway) are now having their biodegradable waste collected separately and transported to one of the biogas plants in the neighbouring municipality of Herning. This group receives no reduced fee. However, a discount can be obtained if the number of containers for unsorted waste is reduced. The actual reduction of the volume is known to be small. During the first seven months of 1998, 40 tons have been collected leading to about 70 tons per year or 2.85 kg/household/week. In conclusion, the method of handling the biodegradable part of the waste among the households living in different types of houses in the municipality of Ringkoebing is as shown in Table below:
Management of domestic biodegradable waste of the municipality of Ringkoebing in1998 by number of households and type of dwelling Type of household Houses* Apartments Summer houses Total Total no.(1996) 6,080 1,138 288 7,506 Home composting 3,600 0 0 3,600 Collection for biogas 125 337 0 462 Exemption, reduced
fee 251 0 0 251 No source separation 2,100 801 288 3,189
All the households with gardens have plenty of space to use the compost from their vegetable waste within the garden. To fulfill the intentions in the Danish legislation for use of organic waste on agricultural soils, the demand for land has been calculated at 5-10 sq.m per person (Reeh, 1996). Similarly the residual component from the biogas plant could easily be disposed of by applying it to the land within the municipality of Ringkoebing - it works out as a maximum of 30 kg per ha. The collected biodegradable waste, currently amounting to 70 tons per year, contains approx. 900 kg of phosphorus which would need about 30 ha on which it could be applied. If a waste collection were introduced with the same efficiency levels as for the rest of non sorting households, then this need will increase to 240 ha. If local farmers cannot take all the organic residues, some can be utilized in the 350 ha of the vegetated areas (estimated by Attwell, 1998) within the residential and amenity areas of the municipality.
Garden and park waste It could be expected that much the same attention would have been paid by the Municipal Authority to source separation and composting of biodegradable material from the gardens and the parks in their care. However, although there is a strategy aimed at directly recycling such material or recycling it after composting, the implementation of this has not been followed up as fully as is the case for domestic waste. The amounts being delivered to the 9 small and 3 larger recycling stations are as shown in Table below. The park and garden waste delivered in 1997 to the municipal recycling stations within Ringkøbing produce the following amounts (tons) of compost and wood chips for soil amelioration and prevention of weed growth (as estimated by the staff) Type Recycling-station Ringkøping Lem & Tim 9 small decentralised Total Garden waste 1,210 500 0 1,710 Branches 615 300 5 920 Compost 750 325 0 1,075 Wood chips 300 150 5 455
The composting of the soft garden and park waste (normally still with a fairly high water content in the material) delivered to the three main recycling stations is not yet working satisfactorily. There are still weed seeds in the compost, which is due to ineffective temperature development during the composting process. This is especially critical because of the recent adoption of weeding without use of pesticides in all public green areas. Because of its condition, the staff at the municipality cannot now use the compost they produce, so it is given away for free to the local citizens; it is recycled, but not efficiently. Branches from the land maintained by the parks staff are chipped and the wood chips used as cover to prevent weed growth in the public amenity areas and private gardens. The compost produced by the gardens and parks maintained by the authority can be used without any restrictions according to Danish legislation. Using the guidelines in the regulations in relation to other organic residuals, where an application rate of 30 kg per ha. is suggested, it is possible to estimate the land requirement at approximately 36 ha, which corresponds to half of the vegetation area in the municipal parks.
Conclusions and recommendations The municipality of Ringkoebing has been a pioneer in reducing the total amount of household waste through the voluntary implementation of home composting. This has resulted in an active participation of about 60% of single family houses. Nonetheless there seems to be a need for continuous follow up in the form of information flow to private households and controls on their dealing with household waste. The problems in handling other parts of the municipal biodegradable waste can be explained partly by the lack of an overall plan for recycling the biodegradable waste in the municipality. A more conscious and wholehearted effort might help to strengthen the weak points of the system. It is recommended that consideration be given to engaging a private company to take care of composting the garden and park waste at the central plant. There is a need to improve the temperature development during the process and if that can be achieved then the quality of and the demand for the compost would increase. A company producing very effective compost shredders, which are sold to most Danish compost entrepreneurs as well as for export, is sited locally in the village of Tim, where it is already shredding the branches at the local recycling station for development and demonstration purposes. There seem to be no strategies and regulations and only a few randomized practices of in-house composting of biodegradable domestic waste in the municipal institutions. A more coherent practice could also be recommended here as an example for the citizens of Ringkøbing. The poor sandy soil of Ringkoebing makes biological waste treatment and use of compost more appropriate here compared with other parts of Denmark where more nutrient-rich loamy soils are common. Improved organisation of composting will lead to better compost quality, which in turn will result in better experiences with use of compost, followed by an increased demand for such products. The overall result will be a more comprehensive recycling of local organic resources.
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References: click here to return to text Attwell, Karen (1998): Ecological sustainability and urban green space. The case of Ringkoebing. Assessment of existing habitat quality of structure zones.
Reeh, Ulrik (1996): Local Composting in Multi-storied Housing, in Management of Urban Biodegradable Wastes, Hansen J. O. (ed.). ISBN 1-873936 58; 343 pp., James and James. |
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