Food waste kitchen sink disposers – Malmo
VA Syd (Water Treatment Plant, Malmo) Malmo Municipality
WHERE: Sweden / Malmo
WHEN: Implemented in period: Ongoing
WASTE MANAGEMENT HIERARCHY: Recycling: Reuse – Reprocessing
TYPE OF INSTRUMENT: Voluntary / promotional (e.g.: business support schemes, green public procurement, infrastructure, fiscal measures)
WASTE STREAMS: Food and organic waste
About: The proposed practice from City of Malmö consists of a pilot project in which kitchen waste disposers have been installed as an easy-to-manage method of dealing with food waste.
The waste disposers have proved to be an effective way of dealing with organic household waste in order to produce biogas.
In cooperation with the developers, the municipality initially installed waste disposers in the kitchens of 200 homes, within the Housing Fair Bo01 area. The waste disposers are the size of a large thermos and were installed beneath the sink.
To avoid the risk of leakage to already polluted watercourses, the municipality did not want to be more organic particles in the sewage system. Separate pipes were therefore routed from the waste disposer. The pipes run to a collecting tank below the ground outside the building. The ground food waste falls to the bottom of the tank, while the water runs onward to the wastewater pipes. A sludge suction truck sucks up the collected waste and transports it to the local wastewater treatment plan, where it is digested and produces biogas.
The developers themselves had to install and maintain the waste disposers and the pipes that were needed in their buildings. The municipally owned water company VA Syd installs and maintains tanks, empties and manages the waste slurry.
VA Syd has started offering waste disposers as an alternative to the separation of food waste in the development areas in Malmo. It was originally intended that the nutrients in the digestion residues would be extracted and used, but this project has not been implemented.
• Funding; budget: The municipality received grants from the Local Investment Programme (LIP) in 2000 for a pilot project with sink waste disposers.
• Programme details: Local Investment Program: LIP Malmö, Bo 01 2000, Action 6
• Environmental investment: SEK 2 Million
• Grant: SEK 1 Million
• The system produces 0.9 – 4.9 m3 biogas per apartment and year, compared with 0.6 – 1.8 m3 per apartment and year for ordinary refuse separation.
• The energy generated by using food waste is 209 kWh/year per capita.
• It is estimated that 10 kg of food waste can ensure sufficient energy to drive an autovehicle about 10 kilometers.
Urban metabolism relevance
The practice aimed on reducing organic wastes while producing energy and fertilisers. In addition, the gases released in the composting processes are captured and used for biogas production. The practice encourages the reduction of materials used in the city and improve citizen life which will breathe a much cleaner air.
•The biogas is used to produce electricity and heating, which lowers CO2 emissions.
•The quality of the organic matter is been high. No post-processing or processing is needed for it to be possible for the waste to be used for biogas production, which saves costs.
•Waste disposers can provide efficient management of organic waste, replacing the need for waste transport.
•Food waste becomes biogas, which is an important aspect of the switch of society from fossil to renewable fuels.
•Polluted air generated by storing the food waste is filtered before being expelled to outside air.
Engaged participatory processes
This project proved a very successful cooperation between different kind of stakeholders (local authorities, private companies and citizens). Also, it had an important impact on the community, as food waste disposers acted as a catalyst for increasing environmental responsibility of many residents.
The practice has an innovative approach, especially in the technique that is using a ground tank for the collection of waste.
The project has provided knowledge on how it is appropriate to design future systems for the separation of organic waste.
Sustainability and replicability
The sustainability of this project have been calculated, its indicators being superior to other similar techniques:
• The system produces 0.9–4.9 m3 biogas per apartment and year, compared with 0.6–1.8 m3 per apartment and year for ordinary refuse separation.
• The biogas is used to produce electricity and heating, which lowers CO2 emissions.
• The food waste disposer has acted as a catalyst for personal environmental thinking for many residents.
• The quality of the organic matter has been high. No post-processing or processing is needed for it to be possible for the waste to be used for biogas production, which saves costs.
The project has shown that cooperation across traditional organisational boundaries makes it easier to start and run projects of this type.
Although home composting have been implemented in different ways and various projects (therefore is easily replicable) , this practice has some innovation issues that could bring more value to the common used techniques.
Other municipalities from Sweden have shown interest in the system.
An increasing interest is expressed in sorting food waste by households, schools, restaurants and groceries in Sweden in 2009, more than 15.000 households sorted the food waste).
Sink disposers proved to be so successful that it subsequently became standard in Fullriggaren neighbourhood, where all 600 dwellings were fitted with waste disposal units from the start.