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Hard and soft science issues to be negotiated to improve urban metabolism

Magid, Jakob (2002) Hard and soft science issues to be negotiated to improve urban metabolism. In: Magid, Jakob; Granstedt, Arthur; Dýrmundson, Ólafur; Kahilouto, Helena and Ruissen, Theo (Eds.) DARCOF report nr. 3, DARCOF.

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In the industrialised world, waste management systems have developed to maturity without primary concern for recycling. These systems have originally been designed to ensure human health and a high local hygienic standard. More recently environmental concerns have been the driving force behind a technological development of sewage treatment with biological removal of N, P and organic matter. This technology addresses some immediate problems in the aquatic environment, but the sewage sludge from the treatment plants contains considerable quantities of xenobiotic compounds and heavy metals, and only a fraction of the nutrients that entered the urban areas, thus making the sludge a non-attractive fertiliser source. In recent years there has been concern about the sustainability of this state of affairs as regards wastewater handling, as well as concern about the fate of the final waste deposits in the environment. In the mid 1990s Danish organic farmers made a point of refusing to accept sewage sludge as a source of nutrients. This sparked a heated debate, and for a time all farmer organisations refused to accept sewage sludge on their fields, leading to severe problems in urban areas. One of the consequences of this conflict is that municipalities are increasingly seeking alternatives to returning sewage sludge to the land (e.g. burning or dumping), in order to rid their dependence of farmers acceptance.
Another consequence has been that the issue of ‘closing the urban-rural nutrient circle’ as part of a sustainable development has received increasing attention among Danish organic farmers. This issue had been identified already in the early days of the organic movement in Denmark, but has never been a top priority. It was accentuated by a strong Swedish emphasis of agricultural use of human urine from source separating toilets that provided inspiration to look at implementing such techniques in Danish urban areas.
One additional factor that has increased the priorities of the issue was the growing realisation that current day organic farmers have a strong bias towards milk production, due to the natural integration of the clover-grass in the production system, that is essential for ensuring an ample supply of fixed atmospheric nitrogen. If more stockless organic farms (e.g. vegetable and grain production for human consumption) are to become economically sustainable, it is important to find ways of using the land with less emphasis on clover grass. One of the ways of doing this is to increase the amounts of nutrients that can be re-cycled from urban areas in a form that is acceptable to organic farms.

EPrint Type:Conference paper, poster, etc.
Type of presentation:Paper
Keywords:Recycling; Urban Rural Co-development
Subjects: Food systems > Recycling, balancing and resource management
Research affiliation: Denmark > DARCOF II (2000-2005) > III.3 (CRUCIAL) Closing the rural-urban nutrient cycle
Deposited By: Magid, Assoc. Prof. Jakob
ID Code:191
Deposited On:21 Oct 2002
Last Modified:18 Jul 2012 10:18
Document Language:English
Refereed:Peer-reviewed and accepted

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