A demonstration project with participation of research institutions

and private companies funded by the EU LIFE-Environment programme

THE “SHORT-CIRCUIT” PROJECTShort circuiting the carbon and nutrient cycles between urban and rural districts byestablishing three new systems for source separation, collection and composting of

organic waste in the greater Copenhagen area (LIFE02/ENV/DK/00150)

SHORT CIRCUITING SHORT CIRCUITING THE ORGANIC THE ORGANIC

LOOPLOOP– Three waste treatment systems – Three waste treatment systems

for the futurefor the future

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Today the release of CO2 (via carbon from fossil fuels and coal) is

much faster than what can be tied up by plant growth. This challenge

is addressed in the Short-circuit project with three innovative ways of

recycling organic residues back to soil. By implementing these sys-

tems the short recycling circuits support community involvement and

clear steps towards sustainability. The circuit of food production, con-

sumption and transformation of leftovers to energy and compost

demonstrated in the project lives up to the health and safety stan-

dards we are used to in modern life concurrently with reduced impact

on nature’s balances.

The project was supported by the European Commission through

the LIFE-Environment programme and was a joint venture between

private and public partners: a food box scheme e-business, an organ-

ic waste treatment company and two universities. The project has

implemented three new systems for source separation and waste

treatment:

1. Collection of vegetable residues from the customers of the

Internet-based box scheme business Aarstiderne Ltd. and

composting of the residues at Krogerup farm (a supplier to

Aarstiderne)

2. On-farm composting (HI-LO-system) of urban waste, in-

cluding source-separated organic household waste, with

farm residues at an experimental farm at The Royal Veteri-

nary and Agricultural University of Copenhagen (KVL)

3. Community involvement in organic waste treatment by a

new combined biogas production- and composting system

(the AIKAN-plant) developed by Solum Ltd.

To evaluate the environmental impact of implementing these sys-

tems, The Royal Institute of Technology in Stockholm (KTH) used the

ORWARE waste management model to quantify the environmental

impacts and compare them with incineration

Organic farms collect leftovers from their own products

Aarstiderne (Danish for Seasons) is a web based trading company that deliv-

ers organic products on a weekly basis under a door to door box scheme. In

this system it is obvious to take back potato peels, carrot tops etc. to regain

organic matter and nutrients for the soil. A van delivers vegetables and takes

back leftovers to be composted. One of the vegetable producing organic farms

(Krogerup Avlsgård Ltd.) undertakes composting of the leftovers and uses the

compost to make new plants thrive. An innovative, very short circuit. Some of

the barriers to be overcome related to requirements from health authorities

concerning the handling of waste by a food delivering company.

To solve the dilemma separate sections of the van were designated to

waste and food respectively. The driver took care of food delivery, while an

assistant collected the waste. The benefit of this system is that organic farm-

ers get their own organic residues back. It must be emphasised that neither

collection nor treatment was financially supported by the local authority in

this project since it was contractually tied up with another company and the

scale was small. In larger scale, a permanent agreement might add economic

benefits to the farmer as well as to the local authority.

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Figure 1 · Aarstidernes waste collection and subsequent composting at Krogerup Farm

Recycling of urban waste to agriculture (HI-LO on-farm

composting system)

Ecologically based thinking and growing demands for water purification

eventually demand that we consider human urine and faeces as a resource

rather than a “getting rid of waste” issue. Toilets that by construction separate

urine from faeces have been available for several years. Urine contains most of

the nutrients, it is basically antiseptic and easy to handle. Contrary to this fae-

ces can contain harmful pathogens. Handling of faeces has thus been an

obstacle for the further development of alternative handling of this waste

fraction in residential areas. Separation toilets have thus been used mostly for

isolated houses, where the possibility of handling faeces separately can be eas-

ily overcome.

In this project KVL developed a HI-LO system (HIgh temperature, LOw

cost, LOw emission composting unit) that was tested to show that urban

wastes mixed with faeces can be turned into a product with safe and benefi-

cial use in agriculture.

The HI-LO composting system met the following specifications: the tem-

perature should be high enough to allow hygienisation of the compost, and at

the same time the system should be inexpensive and manageable using equip-

ment commonly available on farms.

As shown in Figure 2 the compost container can be loaded by a tractor

with a manure spreader in tow.

It was not possible during the project period to get sufficiently large

amounts of faeces to make full-scale tests in the Hi-Lo-system. Instead

source-separated household waste and animal manure were used as feed-

stock, and composting tests were carried out with this material mixed with

different plant residues including rape straw, wood chips and grass clippings.

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Figure 2 · The HI-LO on-farm composting system at KVL’s experimental farm.

Composting of human faeces was done in laboratory-scale experiments, and

these results are applicable to full-scale composting as well.

Process conditions and temperature development during a representative

optimised composting run were as follows: The feedstock was a mixture of

source-separated household waste, farm yard manure, and rape straw. In

total, the temperature was measured at 14 different locations and logged by a

computer every minute. Of these the most important measurements were the

temperatures at the hottest and coolest positions, i.e. in the middle of the

compost mass and at the surface of the composting container. The tempera-

ture in the middle of the compost mass exceeded 70°C for a total of approxi-

mately five days, and the material in this way complied with EU regulations

(at least one hour treatment at minimum 70°C to secure a sanitized product).

The material adjacent to the surface of the container, the coolest part, did not

reach 70°C, but even at this position a maximum temperature of 62°C was

measured and the temperature exceeded 60°C for more than 24 hours in total.

Thus farmers should be capable of handling household waste and faeces

in a farm scale system. An objective that was not completely met was reach-

ing a temperature of 70°C in the entire composting mass for one hour. But

microbial testing has shown the satisfactory result that the HI-LO system did

produce a good quality of compost acceptable for food production.

Community involvement by compost and biogas production

(The AIKAN system)

The AIKAN system is a scalable new treatment plant invented to combine the

benefits of the biogas and the compost processes to obtain energy and clean,

useful compost. The plant can treat different organic solid wastes differently.

Thus sludge, biowaste, faeces etc. are all candidates for treatment. In the proj-

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Figure 3 · From the AIKAN plant.

ect source-separated household waste from different residential areas in

greater Copenhagen was treated, and it was demonstrated to many citizen

groups that the system is reliable and that targets for energy and compost pro-

duction were reached continuously.

The achievements are important: Denmark has recently set up legal

framework conditions primarily for incineration, thus leaving very little space

for recycling of organic wastes. Some 10 to 15 years ago a number of biolog-

ical pilot scale projects failed due to incomplete technology leaving the

impression that the effort of source separation is not worthwhile. By this proj-

ect it has clearly been demonstrated that source separation is an option for the

future and that citizens are willing to make an effort if they believe in the ben-

efits. The AIKAN system can be adapted to different scales, and wastes are

tuned to meet requirements for different compost qualities and energy forms.

Thus the features of the plant make it suitable for application in both inte-

grated waste systems and in developing countries.

A critical angle by ORWARE, a Life Cycle Assessment model

Life cycle assessments (LCA) are very simplified pictures and yet complex

tools used to assess how a product influences the environment in a defined

span of years. It is not evident to understand a waste management system as

an isolated product in itself, but this is exactly what different waste manage-

ment planning academics have been doing over the last years to get closer to

the decision-making process and to assist it with new angles. The Swedish

ORWARE model was used to evaluate the three new systems described above.

Interesting points have been explored: For instance the transport distance and

the moisture content of the waste have a large influence on the superiority of

the Aarstiderne waste collection and composting scheme in comparison with

incineration; and the effectiveness of the biogas engine is important for the

AIKAN system.

Generally, LCA is favourable to incineration because energy considera-

tions are strongly weighed in the LCA tools. This implies that substitution of

energy is determining when oil and coal is our main energy source instead of

renewable energy sources such as wind, water or solar power (with low or no

CO2 emission). Thus, substitution of oil and coal results in major benefits for

energy productive system regardless parts of the wastes originally came part-

ly from oil and coal, which mean they do not replace oil and coal in total, but

prolongs the life cycle of products.

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In this project, however, the ORWARE model demonstrated that all three

systems under certain conditions resulted in environmental improvements

compared to incineration.

Sustainability measures for the future

The three systems demonstrated in this project add considerable value to each

other and show that integration is a keyword for sustainability. By decreasing

collection costs, ensuring that the organic wastes are acceptable as resources

and inventing a reliable energy and compost production system, the circuit

can be made as short and effective as needed. A division of work between

farmers, responsible citizens, local authorities and treatment plants raises

awareness and gives rise to more sustainable resource efficiency. To balance

the CO2 account using organic matter as a fuel is only possible when plant

growth and soil fertility in a global perspective are maintained to balance the

fuel consumption and consequent releases of emissions to the atmosphere.

Therefore it is crucial to focus on the recycling of organic matter and nutri-

ents to soil. In this project the local circuits demonstrate this responsibility to

future generations. What is still missing is clear political targets and econom-

ic drivers to make source separation a must.

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Contact to partners

The Royal Veterinary and Agricultural University (KVL)40, ThorvaldsensvejDK-1871 Frederiksberg CDenmarkAtt.: Jakob Magid (project manager)Phone: +45 35 28 28 28E-mail: jma@kvl.dkHomepage: www.kvl.dk

Solum Ltd.6, Vadsby StrædeDK-2640 HedehuseneDenmarkAtt.: Morten BrøggerPhone: +45 43 99 50 20E-mail: solum@solum.dkHomepage: www.solum.dk

Aarstiderne Ltd.34, BarritskovvejDK-7150 BarritDenmarkAtt.: Svend Daverkosen (also contact person to Krogerup Avlsgaard Ltd.)Phone: +45 70 26 00 66E-mail: info@aarstiderne.comHomepage: www.aarstiderne.com

The Royal Institute of Technology (KTH)79, ValhallavägenSE-100 44 StockholmSwedenAtt.: Otto DüringPhone: +46 8 790 60 00E-mail: otto@ket.kth.se