Marys Medicine

Urban metabolism slu lecture 13

Recycling, Risk Management and Ressource Allocation Jakob Magid, Dept. Agriculture and Ecology
Historical background Future inclusion of food production in cities? Waste recycling potentials and risks Risk related to recycling and to growing urban food Land and water associated with food production and waste disposal Jakob Magid, Dept. Agriculture and Ecology

.Fifty years ago nearly all London had every house cleaned into a large cesspool …. Now sewers having been very much improved, scarcely any person thinks of making a cesspool, but it is carried of at once into the river. The Thames is now made a great cesspool instead of each person having one of his own.'. Thomas Cubitt, 1840 Jakob Magid, Dept. Agriculture and Ecology
'Death in the Cup' A small girl in Hamburg drinkinginfected water during the 1892 epidemic; a few hours later the child was dead, This picture,fromthe Illustrated London News, reminds us of the fear the diseasestill caused. (Illustrated London News, 1892) Jakob Magid, Dept. Agriculture and Ecology

Justus von Liebig Jakob Magid, Dept. Agriculture and Ecology
In a letter to Sir Robert Peel, Prime Minister of the UK in 1840,
Justus Liebig wrote:

The cause of the exhaustion of the soil is sought in the customs
and habits of the towns people, i.e., in the construction of water
closets, which do not admit of a collection and preservation of
the liquid and solid excrement. They do not return in Britain to
the fields, but are carried by the rivers into the sea.
The equilibrium in the fertility of the soil is destroyed by this
incessant removal of phosphates and can only be restored by an
equivalent supply. If it was possible to bring back to the fields
of Scotland and England all those phosphates which have been
carried to the sea in the last 50 years, the crops would increase to
double the quantity of former years.

Jakob Magid, Dept. Agriculture and Ecology
When London's authorities decided to construct a sewage disposal rather than a recycling system, Liebig decided that it was necessary to find ways to replace the fertility removed by cities from farmland by artificial means. He set about developing artificial fertilisers to keep the land feeding cities productive. Today, the use of artificial fertilisers is the norm all over the world. Jakob Magid, Dept. Agriculture and Ecology
The introduction of water-closets into most parts of England results in the loss annually of the materials capable of producing food for three and a half million people; the greater part of the enormous quantity of manure imported into England being regularly conveyed to the sea by the rivers. like a vampire it hangs upon the breast of Europe, and even the world; sucking its life-blood….
Originally quoted from:Liebig von, J. (1855) Die Grundsatze der Agriculturchemie mit Rucksicht auf die in England angestellten Untersuchungen. Braunschweig.
Jakob Magid, Dept. Agriculture and Ecology
Copenhagen's night soil solution Jakob Magid, Dept. Agriculture and Ecology
Jakob Magid, Dept. Agriculture and Ecology
Jakob Magid, Dept. Agriculture and Ecology
Blue skies technologies
Jakob Magid, Dept. Agriculture and Ecology
Cities are metabolising and growing organisms in the global landscape. A fundamental and simple prerequisite for sustainable development is that cities of the future must control their metabolisms to an extent where recycling of waste products is near complete. In the industrialised world, waste management systems have originally been designed to ensure a high local hygienic standard and has been developed to maturity without primary concern for recycling. Jakob Magid, Dept. Agriculture and Ecology
Current Household Waste Production pr. person / yr
Total volume(including water for bathing and washing): Organic household waste: Thus: 90-95 % of the nutrients, much of the organic matter and >99% of pathogens, is contained ca. 1% of the waste volume….
The disposal of this waste is estimated at an annual cost of ca. 350 Euros pr. Danish citizen Jakob Magid, Dept. Agriculture and Ecology
Present day distribution
of Nitrogen
14 g mostly from urine and faeces delivered via wastewater to sewage treatment 1,7 g in solid waste (organic waste from household and garden) N distribution after
increased utilization
of urine and faeces
12 g utilised as fertiliserfor agricultural land 1,5 g delivered via waste water to sewage treatment 2,2 g in solid waste (organic waste from household and garden)to be recycled upon treatment (composting or bio-gas production) Jakob Magid, Dept. Agriculture and Ecology
Future waste management systems could be based on a
separate handling of these fractions
avoiding the need to purify sewage effluent with regard to nutrient content and returning the nutrients to land based production systems Jakob Magid, Dept. Agriculture and Ecology
Future inclusion of food production in cities?
Urban Agriculture Narratives
Currently, we import food from all over the world and in some cases, the food generates its own weight in CO2 during its journey around the world - such as New Zealand gala apples As industrial agriculture fails due to a scarcity of oil- and gas-based inputs, we will certainly have to grow more of our food closer to where we live, and do it on a smaller scale.
The reason why we need vertical farming is that horizontal farming is failing, Urban Agriculture Narratives: Canada/US/EU
Urban agriculture is an environmental and social movement acting on the critique of the industrialized food system, with the desire to reconnect to food and develop and implement sustainable and local alternatives. The urban farming initiatives often build on a culture of community values by re-integrating the production / consumption cycle within the local community were the production is carried out in a social context by active members of the community. Roles of urban agriculture in Japan (MAFF):
Source of fresh and safe products, including organic and low-
chemical crops, that are increasingly demanded by urban
consumers, based on relationships of trust between farmers and
city dwellers.
Opportunity for urban residents' engagement in agricultural
activities, both directly (e.g., allotment gardens) and through
exchange between producers and consumers with the sales of
agricultural products at local farm stands.
Open space for disaster management, including fire spread
prevention, evacuation space for earthquakes and open space in
case of other disasters.
Resource for recreation and well-being, including green space for
personal leisure and spiritual comfort.
Education and awareness-raising for improving urban residents'
understanding of agriculture and food issues.
Children with no understanding of where
food comes from
Obesity - lifestyle
Human / Nature interrelationship
Short break
A pointer for estimation of nutrient production on campus Jakob Magid, Dept. Agriculture and Ecology
A ballpark figure for prescence 3500 students might spend 25 hours per week, 40 weeks per year (max) appr. 400 person 1500 employees would spend 40 hours per week 46 weeks per year appr. 315 person years Jakob Magid, Dept. Agriculture and Ecology
In current practise we could recycle solid waste
Magid,J., Eilersen,A.M., Wrisberg,S., Henze,M., 2006. Possibilities and barriers for
recirculation of nutrients and organic matter from urban to rural areas: A technical
theoretical framework applied to the medium-sized town Hillerod, Denmark. Ecological
Engineering 28, 44-54.
Low – techLocal Results in a loss of N 0.2 kg NPK N
0.6 kg NPK N
High – techCentralised How far does that take us?
10 g N per m2 equals100 kg N ha-1 Intensive vegetable production requires 200 kg N ha-1 High yield fruit and berry 100 kg N ha-1 0.2 kg NPK N
One single person could fertilize 10 – 20 m2with compost from household waste System approaches Storage tank
Collection tank Sludge truck
Storage tank
Sewage pipe
Sewage plant
Sludge truck
Sludge truck
Storage tank
Sewage pipe
Sewage plant
Jakob Magid, Dept. Agriculture and Ecology
What would be the potential problems in applying a recycling strategy ? Jakob Magid, Dept. Agriculture and Ecology

Heavy metals and Xenobiotics in human urine (from grassroot–
projects) compared to standard values for Danish sewage sludge
and Municipal Solid Waste compost (1998).
--------- mg kg-1 N ------------- Jakob Magid, Dept. Agriculture and Ecology
Fecal contamination and microbial die-off was studied for a 6-months period in tanks containing urine collected from urine separating toilet systems, including family-based and public separating toilets (urban ecology demonstration projects). E. coli was found only in a few samples in low numbers in the first month of study, whereas Salmonella and Campylobacterspp. were not found in any sample. The initial concentrations of fecal enterococci varied, but were usually around 105-106/ml with a rapid reduction to below the detection limit (<10/ml) following 3 to 4 months of storage. The protozoan parasites, Cryptosporidia and Giardia, were found in a few samples. Jakob Magid, Dept. Agriculture and Ecology
Relative risk assessment – a level Comparison analyses of pig and cattle slurry used for fertilization in agriculture showed in general much higher concentrations of bacterial indicators and parasites than found in urine. These initial results indicate that urine may be used as fertilizers in agriculture with little if any additional risks compared with animal slurry. Jakob Magid, Dept. Agriculture and Ecology
Microbial divertity, antibiotic resistance and horizontal gene transfer Soil sampled right after fertilizer amendment: Isolation of Pseudomonas from soil using selective media (NAA 1:100) - NAA, NAA+Gentamycin, NAA+Tetracycline Antibiotic resistance in Pseudomonas Average CFU g-1 soil (all treatments, all sampling times):NAA Abundance of Gentamicin-resistant Pseudomonas Abundance of Tetracycline-resistant Pseudomonas Multiresistance in Pseudomonas Multiresistance of Gentamycin-resistant Pseudomonas Multiresistance of Pseudomonas in general Multiresistance of Teteracycline-resistant Pseudomonas The chemical quality of sludge in Western countries has constantly improved and concentrations of potentially harmful and persistent organic compounds have decreased to near background levels. There is an overwhelming body of evidence indicating that recycling of sewage sludge on farmland is not constrained by concentrations of organic contaminants found in contemporary sewage sludges. Risks and controvercies – reductionist vs holistic assessment of urban agriculture Jakob Magid, Dept. Agriculture and Ecology
Faculty of Science Denmark is a highly regulated society Occasionally one
would think that
fear for
Report from the EPA environmental
risks is
disproportionately
affecting the
environmental
legislation
Jakob Magid – Institut for Jordbrug og Økologi Faculty of Science The studied compounds were only to a very limited extent taken up by roots and transported to other parts of the plants, but could be transferred via direct contact with soil The substances were found in the highest (very low) concentrations in root vegetables (potatoes and carrots) but could be almost completely removed by peeling Since contact with soil and soil dust is not practically avoidable there might be a possibility for an unacceptably high exposure towards children for vegetables….
Growing fruit and berries may happen without contact with soil and soil dust – so this is not a problem….
Faculty of Science Presently Urban Farmers in DK are constrained by
the environmental regulations that are tied to soil
polution – but is this the real problem?
Jakob Magid – Institut for Jordbrug og Økologi Faculty of Science The soil eater ……
Jakob Magid – Institut for Jordbrug og Økologi Faculty of Science What about air polution? Jakob Magid – Institut for Jordbrug og Økologi Faculty of Science A tentative relative risk assessment based on the EPA report Additional cancer cases over 70 years (per 1,000,000 inhabitants) as a result of high intake of vegetables grown in Annual: 0.009 - 0,036 BaP-contaminated soil Additional early deaths pr. ýårdue to. urban background airpollution i PM2,5 Additional annual hospitalizations due to cardiac and respiratory diseases Faculty of Science Is it dangerous to eat urban grown food? What about food from the supermarkets? Might active ingredients be transferred from the packing ? Jakob Magid – Institut for Jordbrug og Økologi Jakob Magid, Dept. Agriculture and Ecology
Jakob Magid, Dept. Agriculture and Ecology
Conclusions on risk assessment It is unlikely that urban grown food constitutes a threat to human health – rather the opposite Occasionally reductionist environmental risks assessments are disproportionately affecting the environmental legislation We need to work on a holistic assessment of the urban agriculture food system Potentials and Needs – how do we • How much land should we use for recycling? • How much land do we need for food? • How much water do we need for food? Using the Person Equivalent (PE) –
a simple robust bottom up approach
Jakob Magid, Dept. Agriculture and Ecology
Jakob Magid, Dept. Agriculture and Ecology
How much water do we need for food? Blue: surface and ground water Grey: water to assimilate pollutants Jakob Magid, Dept. Agriculture and Ecology
PE water footprint Jakob Magid, Dept. Agriculture and Ecology
Some facts and figures
The production of one kilogram of beef requires 15000
litres of water (15 m3)
The water footprint of a 150-gram soy burger produced in
the Netherlands is about 160 litres. A beef burger from the
same country costs about 2000 litres.
The water footprint of Chinese consumption is about
1070 cubic meter per year per capita. About 10% of the
Chinese water footprint falls outside China.
The water footprint of US citizens is 2840 cubic meter per
year per capita. About 20% of this water footprint is
external.
Jakob Magid, Dept. Agriculture and Ecology
Heavy meat eater 4000 m2; Demitarian 2000 m2
Vegetarian: 1000 m2
Jakob Magid, Dept. Agriculture and Ecology
Putting it all together – a standard • Food derived land allocation 3000 m2 • Food derived water allocation 1500 m3 (equivalent to the rain falling on 1900 m2 in • Waste derived land allocation 250-350 m2 Jakob Magid, Dept. Agriculture and Ecology
Going back to the earlier part of todays lecture … Jakob Magid, Dept. Agriculture and Ecology
Jakob Magid, Dept. Agriculture and Ecology
Is vertical farming the grand Jakob Magid, Dept. Agriculture and Ecology
Thank you for your attention ….
Jakob Magid, Dept. Agriculture and Ecology

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