SiEUGreen - D2.4 Blue Technology (T2) Ready 2

The SiEUGreen project aims to enhance the EU-China cooperation in promoting urban agriculture for food security, resource efficiency, and smart, resilient cities. Circular economy and utilization of domestic organic urban waste resources for the production of fertilizer and soil amendment products for urban and peri-urban agriculture, as well as energy for local use, are essential aspects of the showcases in Fredrikstad and Changsha, especially. The conversion of waste resources and water handling in the SiEUGreen project termed Blue Technology. This deliverable, D2.4 “Blue Technology (T2) Ready 2”, is based on research and investigations carried out in the first 18-month project period and presents blue technologies related to the collection of liquid waste for recycling that is ready for implementation in the SiEUGreen showcases and technologies for processing of grey and stormwater. The different technologies studied are presented in fact sheets. Presentation in fact-sheets facilitates later upgrading to practice abstracts. The latest updated status of the technologies and the potential challenges in the implementation of these technologies in urban settings are also presented. The majority of the nutrients in wastewater is found in toilet waste or blackwater. If blackwater is collected in a concentrated form further processing by anaerobic digestion yielding biogas or composting is facilitated. Low flush and dry toilet systems are therefore evaluated. Vacuum systems form the three leading manufacturers worldwide are investigated. Two of the manufacturers have most of their experience from the marine and one is specializing in the on-shore market. However, all three are gearing towards the on-shore market as this is the primary future market of vacuum toilet technology. All companies can deliver robust and reliable systems suitable for high-rise buildings as in the Fredrikstad and Changsha showcase. However, they are dependent on electricity supply and systems with small vacuum reservoirs are more vulnerable if the power goes than systems with large vacuum reservoirs (tanks or large piping systems). The systems require correct construction, operation, maintenance and trained caretakers. Urine is mostly sterile and can be utilized in agriculture without other processing than six months of storage. Urine diverting toilets can also be used in high-rise buildings. However, due to some technical problems and user acceptance, few toilets are available on the market today, but a new Swiss urine-diverting toilet has a promising design and function. This toilet will be available on the market next year and is therefore not recommended in the SiEUGreen showcases other than that for demonstration. Dry toilets are not suited for high-rise buildings but are ideal as a stand-alone toilet where there is no water infrastructure. However, user acceptance may be more difficult than for a vacuum toilet and similar to that of the urine-diverting toilet. A solar-driven toilet, developed at NMBU, is being used in the Århus showcase and will be investigated for user acceptance and compost quality. SiEUGreen aims at treating the greywater (water from showers washing and sinks) to swimming water quality in a facility next to the building in the showcases in Fredrikstad and Changsha. Treating greywater decentralized will reduce the pressure on the existing sewers as the high-quality effluent can be safely discharged to the storm-water system. NMBU and NIBIO have developed biofilter wetland systems for the cold climate that produces swimming 4 water quality. A system has been in operation in Oslo since the year 2000 with good results. A similar system is suggested in the Fredrikstad showcase. However, the system has a footprint and the septic tank used for 64 flats, as in Fredrikstad, becomes both expensive and large. Trials have therefore been performed in the NMBU laboratories with an aerated moving bed biofilter system. The tests are promising and can cut the footprint of the septic tank and biofilter in the planned system to 1/10th. If ready before installation, more compact components will be used. Fascinating trials have been performed in the NMBU laboratories using green walls for greywater treatment. The vertical greywater treatment system consists of vertical infiltration into porous media. Greywater treatment in a vertical vegetated wall can be integrated with hydroponic food production into a double skin facade for installation on new high-rise buildings or as a retrofit on existing buildings with adequate solar exposure.