Papers by Eeva-Liisa Viskari
There is increasing awareness and concern about water pollution and water scarcity, and sanitatio... more There is increasing awareness and concern about water pollution and water scarcity, and sanitation has been acknowledged as a critical dimension of both. This paper summarises the findings from the 2nd International Dry Toilet Conference 2006 (DT2006), held 16-19 August, 2006, in Tampere, Finland. The main objective is to publicise a range of research and real life experiences dealing with an uncommon subject: dry sanitation (DS). It was concluded, among other things, that continued technical and institutional development is needed because DS as a decentralised option calls for innovative approaches. Dry toilets based on urine diversion were recommended also for urban areas as urine has high concentrations of both nutrients and such micro-pollutants as pharmaceuticals and oestrogens, both of which are difficult and costly to remove by conventional wastewater treatment processes. The Conference urged continued serious and systemic research, also in the real life context, and taking s...
Promoting the circular economy of water supply in the urban environment Efficient nutrient recove... more Promoting the circular economy of water supply in the urban environment Efficient nutrient recovery plays an important role in the transition to a circular economy and a more sustainable food system, and the role of cities should also become an increasingly prominent part of the circular economy and nutrient recovery. The development and implementation of new solutions is also supported by the interest of cities in profiling themselves as pioneers for sustainable development. In cities, e.g. nutrient recovery can mean nutrient-wise sanitation, such as separating and treating black water separately from other wastewater. This makes it possible to produce more nutrient-rich products with fewer pollutants than in current system and enable energy production locally. The Nutricity project which is coordinated by the City of Tampere and promotes nutrient recovery, has explored the possibility of applying sanitary technologies based on source separation and technical solutions for nutrient recovery in the new Hiedanranta residential area on a super-block scale. The project has e.g. piloted various sanitation system alternatives at Hiedanranta Manor and Drying Plant, conducted surveys on their use, tested techniques for further processing of sanitation wastewater fractions and researched source-separated urine treatment options in a real environment. The operating model presented in this report is aimed at cities and municipalities as a tool to promote nutrient recycling in new urban housing areas and, where applicable, also in areas under renovation. The experience gained from the project shows that it is a challenge to break the current business and service models. The change challenges existing organizations to develop their operations and find new partners and practices that can be limited by legislation. The implementation of circular economy in cities requires the development of cooperation between different sectors and the creation of new ways of working, as well as e.g. training of designers. There is a gap between strategic goals and practical planning and implementation, which makes it difficult to achieve the goals. Urban planning as well as urban investments should be increasingly used as experimental and development environments. International examples show that experiments in smaller-scale source-separating sanitation sites have enabled a shift to larger-scale design and implementation. Source-separation systems based on nutrient recovery are seen as contributing to a sustainable future and pioneering as a whole. In urban areas, such solutions could be particularly relevant in new residential areas or areas undergoing renovation, in which case the integration of source-separating sanitation into measures to reduce the carbon footprint of housing would be a key. Construction should be guided holistically in a more sustainable direction, with nutrient recovery as an area that is strongly linked to other areas such as local energy production and consumption. In addition to technical changes in wastewater collection and treatment, sanitation solutions that support nutrient recovery also require legislative changes. Source-separating sanitation can produce completely new recycled nutrients of human origin, the utilization of which should be allowed under certain boundary conditions.
Frontiers in Environmental Science, 2020
Alkaline dehydration can treat human urine to produce a dry and nutrient-rich fertilizer. To eval... more Alkaline dehydration can treat human urine to produce a dry and nutrient-rich fertilizer. To evaluate the technology at pilot-scale, we built a prototype with capacity to treat 30 L urine d −1 and field tested it for the first time at a military training camp in Finland. We operated the system for 3 months and monitored the recovery of nutrients, end-product composition, physicochemical properties and energy consumption. Results revealed that the system received less urine than anticipated, but achieved high dehydration rates (30-40 L d −1 m −2), recovered 30 ± 6% N, and yielded end-products with 1.4% N, 0.9% P, and 8.3% K. However, we demonstrated that the system had potential to recover nearly 70% N and produce fertilizers containing 13.2% N, 2.3% P, and 6.0% K, if it was operated at the design capacity. The energy demand for dehydrating urine was not optimized, but we suggested several ways of reducing it. We also discussed concerns surrounding non-essential heavy metals, salts, and micropollutants, and how they can be overcome to safely recycle urine. Lastly, we pointed out the research gaps that need to be addressed before the technology can be implemented at larger scale.
Frontiers in Sustainable Food Systems, 2018
The growing demand for food and the increasing costs of cultivation are posing a challenge for ag... more The growing demand for food and the increasing costs of cultivation are posing a challenge for agriculture. Diminishing phosphorus reserves, as well as the energy intensive method of producing nitrogen fertilisers are drivers for more intensive reuse of different organic fertilisers, such as manures and excreta. Source separation and fertilisation with human urine can be one option for nutrient reuse. Urine contains all the main nutrients as well as micronutrients in soluble form, but it also contains chemicals, like pharmaceuticals and hormones. The aim of this study was to examine the efficiency and safety of the use of source separated human urine as a fertiliser for barley (Hordeum vulgare). The fertiliser efficiency of source-separated urine was examined in field-scale experiments for the first time in Finland. Two separate cultivation experiments in two fields and barley varieties were conducted. The efficiency of urine as a fertiliser was compared to corresponding amount of mineral fertiliser. No fertiliser was applied to one plot in order to create a reference treatment. The two experiments were conducted using variety Wolmari with 54 kg N ha −1 and variety Harbinger with 100 kg N ha −1. The barley grain and straw yield grown with urine fertiliser was equivalent to the yield in mineral fertilised plots. The growth of barley in both fertiliser treatments was slightly faster, compared to non-fertilised treatment. There were no significant differences between the treatments in terms of protein content of the grain although the results varied in terms of the thousand grain weight (TGW) and germination. The urine analyses indicated that there were no pathogen indicators, nor heavy metal concentrations, exceeding the limit values set by legislation. The main nutrient concentrations (N, P, K) would also meet the requirements for a fertiliser product according to Finnish legislation. Pharmaceuticals and hormones were found from the urine, but apart from progesterone, all of them presented extractable values in soil below the detection limits, and they were not detected in measurable amounts in barley grain at the end of the growing season. These results suggest that source separated urine could be an efficient fertiliser in crop cultivation.
Journal of Cleaner Production, 2019
The availability of mineral fertilizers is becoming more challenging in the future. In source sep... more The availability of mineral fertilizers is becoming more challenging in the future. In source separated human urine, nutrient ratio is suitable for fertilizer use and nutrients are readily available for plants. In this study the aim was to acquire scientific data of the environmental impacts and nutrient potentials of wastewater separating systems, i.e. urine and blackwater source separation. At the same time, general acceptance on the use of human urine in agriculture wanted to be improved. In addition, the value of urine as a fertilizer was calculated. The focus of the study was on rural areas but comparison between different systems included also the nutrient potential of urban areas as well. Based on the results, human urine was found to be an environment friendly fertilizer. Applying source-separation systems in rural areas, four times more phosphorus and over thirty times more nitrogen could be recovered compared to the current wastewater treatment system. Furthermore, eutrophication impact is reduced to one fifth. However there is a risk of increased soil acidification but it can be minimized with advanced spreading techniques, like deep injection. The results of this study support the use of source-separation technologies for nutrient recovery.
The suitability of constructivist teaching strategies was studied in the context of environmental... more The suitability of constructivist teaching strategies was studied in the context of environmental engineering education. The object of this study was a course called Water and Soil Analyses, which is taught to third-and fourth-year environmental engineering students. Using pre-lecture assign-ments, focusing on peer interaction, having the students take responsibility for making their own research plans, taking advantage of the PDEODE method, doing fieldwork and laboratory analysis, and producing a report and presenting the results in a seminar, were all tools for motivating and engaging students to take responsibility for their learning. In addition, assessment of the course was spread throughout the course, without a traditional exam. When assessing the students' learning it was clear that the learning results were excellent. This includes both subject matter and other skills, such as social, teamwork and communication skills. The students' feedback was also mainly positive...
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Papers by Eeva-Liisa Viskari