Source separation systems – a solution for future generations
Source separation systems can be the way leading to a sustainable environment for islands, lakes and seas for future generations. That's the main result shown in the final report for a development project. The project has been prepared to provide support to Swedish municipalities and water companies in building and planning for the future. The researchers' experience will be used for the expansion of the H+ city district in Helsingborg.
Project contact: Marinette Hagman, Research Manager, Sweden Water Research
Summary of the project
Future requirements regarding water emissions and nutrient recycling can be fullfilled with the introduction of source separated waste and wastewater systems. The objective with this project was to support municipalities and water companies who consider source separating systems through 1) a compilation of experiences of planning, decision making and implementation of source separated systems, 2)Life cycle cost and socio-economic analysis, and 3) highlight important planning and implementation issues. The starting point of the project was a system solution planned for the new city district H+ in Helsingborg including separate handling of 1) blackwater, 2) greywater and 3) food waste milled with waste disposers. The project group consisted of representatives from SP Urban Water Management, Lund University and NordVvästras Skånes Vatten och Avlopp AB.
Challenges identified regarding planning and implementation are 1) adaptation to laws and regulations, 2) cooperation with the agriculture, 3) anchoring with contractors, and 4) communication with residents. Regarding the technology, experiences of sewer transport of Blackwater are few but promising. It was indicated that elderly vacuum systems have quite many disruptions compared to conventional sewer systems. There are on the other hand no negative experiences of new applications of vacuum systems. The treatment and extraction of nutrients from blackwater is not
a very developed area and there is a need for a market for recycling in order to further develop the area. A life cycle cost model was used to estimate the costs of a conventional versus a black water system using an annuity method. The starting point is that all infrastructure must be changed and with a 50 year perspective. The life cycle cost analysis showed that source separation systems for blackwater and solid organic waste are 20% more costly than a conventional system. It is not an easy task to estimate the socio-economic value of applying source separation systems due to environmental benefits and decreased generation of greenhouse gases. First of all there is a lack of good data. The result from a limited analysis was that the increased economic value with
introduction of source separation systems corresponds to 4% of the total system costs. This corresponds however to 24% of the increased costs of introducing a separation system compared to a conventional system. Therefore socio-economics, in spite of the incompleteness, can still be a decision support together with a life cycle cost analysis.
In summary, source separation systems have the potential to fulfil the environmental target of nutrient recycling and could therefore be considered for new city districts or in areas where the sewer system and the buildings need renovations. This study shows that the experiences of Blackwater separation system are few but promising. Development of planning and implementation issues is however needed.