The purpose of this study was to compare the energy use and climate impact of extracting phosphorus (P) from sewage sludge, compared with mineral phosphorus from mining. The two processes that are studied are struvite precipitation and extraction of phosphorus from sludge ash (AshDec). We also looked at the potential recycling rate of plant nutrients in the different systems.

In the study, we have calculated the environmental impact of introducing the processes for P-recovery, related to a conventional sewage treatment plant with chemical precipitation. It is therefore only the differences that arise in comparison with the reference plant that are included in the calculations. You can think like this: there is an existing sewage treatment plant, where you introduce P recycling. All changes in environmental impact that arise in connection with the investment in this new process are burdens the new P-product.

The results show that the AshDec scenario has the best recovery rate of phosphorus and energy balance, while the struvite scenario shows the best return rate of nitrogen and the lowest climate impact. However, the sensitivity analyzes show that the results are strongly influenced by different assumptions. For the AshDec scenario, assumption about nitrous oxide emissions from incineration of sludge as well as the handling of energy surplus is crucial. For the struvite scenario, assumptions around the reconstruction of the sewage treatment plant to biological phosphor cleaning is of great significance, especially if the biogas production is affected.

Ecotechnologies have the potential to reduce the use of finite resources while providing a variety of co-benefits to society, though they often lack in market competitiveness. In this study, we investigate the sustainability of ecotechnologies for recovering carbon and nutrients, and demonstrate how a so-called “bottom-up” approach can serve as a decision-making instrument. Based on three case study catchments with a focus on domestic wastewater in Sweden and Poland, and on manure, grass and blackwater substrates in Finland, we apply a cost–benefit analysis (CBA) on system alternatives derived from a participatory process. After drawing on an initial systematic mapping of relevant ecotechnologies, the scope of the CBA is determined by stakeholder suggestions, namely in terms of the considered assessment criteria, the physical impacts and the utilised data. Thus, this CBA is rooted in a localised consideration of ecotechnologies rather than a centralised governmental approach to systems boundaries. The key advantage of applying such a bottom-up approach is that it has gone through a robust participatory selection process by local stakeholders, which provides more legitimacy to the decisions reached compared with traditional feasibility studies. Despite considering the revenues of the recovered products as well as the provision of the non-market goods CO2 mitigation and reduced eutrophication, findings from this study indicate that the benefits of the considered ecotechnologies are often outweighed by their costs. Only anaerobic digestion of agricultural wastes appears to be economically feasible under the current conditions, highlighting that further efforts and incentives may be required to mainstream ecotechnologies. © 2021, The Author(s), 

Restoring nutrient circularity across scales is important for ecosystem integrity as well as nutrient and food security. As such, research and development of technologies to recover plant nutrients from various organic residues has intensified. Yet, this emerging field is diverse and difficult to navigate, especially for newcomers. As an increasing number of actors search for circular solutions to nutrient management, there is a need to simplify access to the latest knowledge. Since the majority of nutrients entering urban areas end up in human excreta, we have chosen to focus on human excreta and domestic wastewater. Through systematic mapping with stakeholder engagement, we compiled and consolidated available evidence from research and practice. In this paper, we present ‘Egestabase’ – a carefully curated open-access online evidence platform that presents this evidence base in a systematic and accessible manner. We hope that this online evidence platform helps a variety of actors to navigate evidence on circular nutrient solutions for human excreta and domestic wastewater with ease and keep track of new findings. 

There exist numerous ecotechnologies for recovery and reuse of carbon and nutrients from various waste streams before they are lost to runoff. However, it remains largely unknown how growing implementation of such ecotechnologies affect nutrient emissions to surface waters at catchment scale. Here, this knowledge gap is addressed by application of SWAT model in three case study catchments draining to the Baltic Sea: Vantaanjoki (Finland), Fyrisån (Sweden) and Słupia (Poland). Sustainability analysis with Multi-Criteria Analysis was applied in the stakeholder workshops in the case study areas to assess different ecotechnology alternatives. The following ecotechnologies received the highest sustainability scores: in Vantaanjoki anaerobic digestion, based on mostly agricultural residues; in Fyrisån source-separation of wastewaters; in Słupia nutrient extraction within the wastewater treatment process. The effect of application of digestate on agricultural soils in the Vantaanjoki catchment was simulated by adjusting the model parameters describing the organic carbon content and physical properties of soil. The results showed small reductions of nutrient loads to the Gulf of Finland. Larger reductions of nutrient loads to Lake Mälaren in Sweden and the Baltic Sea in Poland were achieved as a result of the wastewater treatment upgrades. In the Fyrisån catchment, higher relative reductions were simulated for TN than TP, and in dry years than in wet years. Although the studied ecotechnologies did not show as high effectiveness in nutrient load reduction as combinations of traditional Best Management Practices reported in literature, they do have other multiple benefits including crop yield increase, electricity, heat and bio-based fertilizer production.

The Swedish project P-to-Product focused on developing and adapting methods to promote recirculation of phosphorus (P) products extracted from sewage and sewage sludge. The project consisted of three work packages: 1) market introduction, 2) environmental impacts and 3) agricultural requirements. In wp 1 opportunities and barriers were identified and policy recommendations developed. This was done through interviews, surveys and workshops with stakeholders from sewage utilities, innovation companies, the fertilizer industry, the federation of Swedish farmers and national authorities. In wp 2 a simplified Life Cycle Assessment (LCA) was developed focused on nutrient recycling, global warming potential and energy use. In addition to this a chemical checkpoint was formulated with chemical analysis of a wide range of pollutants. For the development of methods in wp 2, granulated or pelleted nutrient products from the companies EkoBalans (a struvite based product with nitrogen and potassium added) and Outotec (a P-product with origin from incinerated sewage sludge) were used as case products. These products were also used in wp 3 where physical properties were evaluated and spreading tests were executed using existing machinery. The project provided a useful set of methods which soon will be complemented with methods to assess plant nutrient efficiency.

There has been an increased focus on nutrients recycling specifically in Europe over the last years. This paper gives an overview of the situation in nine countries regarding status, policies and future perspectives in the area of phosphorus and nitrogen recycling from wastewater and sewage sludge. The study includes the situation in Sweden, Germany, Switzerland, Denmark, Netherlands, Great Britain, Norway, Finland and Canada. The information was received through interviews with national coordinators complemented with information from literature and other sources. The following topics were included:

- Main management of sewage sludge and phosphorus extraction today

- Expected future management of sewage sludge and phosphorus extraction, 5-10 years ahead

- Experiences of nitrogen extraction from sewage

- Experiences of source separated sewage systems

- National targets, regulations and financial instruments to promote nutrients recycling from sewage

- Ongoing research, development and innovation activities

From the compilation of the results the countries were categorized in three groups 1)

The Legislation group, 2) the Investigation group, and 3) the Limit group. The categorization was based on the current management of sewage sludge in combination with ambitions and future perspectives.

The legislation group includes Germany and Switzerland where the latter is the only country with a prohibition of spreading sewage sludge in agriculture, implemented 2006. Germany is a frontrunner with a newly implemented legislation. Spreading of sewage sludge is today rare in Germany since limits are getting more and more strict over time. Incineration is a common method in both Switzerland and Germany and both countries are in the frontline regarding the introduction of phosphorus extraction from the ashes.

Six countries still use considerable amounts sewage sludge on agriculture, where four countries; Great Britain, Denmark, Norway and Canada has no plans in changing this (the Limit group). The Netherlands is also part of the Limit group but is different since they do not spread any sewage sludge on agriculture due to tough limits.

The investigation group contain Finland and Sweden. They are spreading relatively large amounts of sewage sludge but has also an ambition to start extract and recycle phosphorus. This is done with support of a policy in Finland and in with a governmental investigation in Sweden with aim at formulating new regulations.

A general observation is that the current handling of sewage sludge in each country is more dependent on local conditions than a more scientific evaluation of different opportunities. The explanations can rather be found in the structure of the agriculture (the access of manure or the access of agricultural land convenient for spreading sewage sludge), traditions and attitude to incineration, possibilities of alternative use of sludge (cover of mines and landfills), debate of sewage sludge or other reasons.

Research and Innovation Agenda for Recovery of Nutrients from Wastewater

Projects funded on the topic of nutrient recovery and reuse in Sweden over the past years have been scattered, lacking a coherence in direction and coordination between the numerous research funding organizations. This agenda has been developed with the purpose of creating a framework and common understanding of what research and innovation is necessary to move forward in a transition to a circular nutrient economy. The goal was to identify and prioritize the R&I needs in order to enable a productive dialogue between investors, researchers and other crucial societal actors including organizations, the public sector and the industry.

The results and conclusions presented in this report are mainly drawn from a workshop in September 2019, with around 40 participants representing the water and wastewater sector, municipalities, academia, the agricultural sector, the industry and Swedish national agencies.

In the transition to a more circular management of nutrients including waste streams, several challenges were identified. The identified challenges in a nutshell:

- Current system solutions are not optimized, there is a lack of holistic approach- Business models and incentives to choose products based on recovered nutrients on the market are missing- Technology needed for circular management of nutrients are in general on a low technology readiness level- Recovered nutrient products must maintain a uniform and high quality in order to compete on the market and the requirements should be the same for all fertilizers.

The agenda concludes that the research and innovation actions to meet the challenges should follow a holistic approach that includes the entire value chain of nutrient management in the food system. All essential nutrients in the food system and other resources in its waste streams should be considered, to maximize efficient and circular nutrient management. Based on this understanding, that a holistic approach is of such importance to target the identified challenges, the research and innovation needs were identified as:

- Develop a national plant nutrient management strategy that describes holistically how to manage nutrients overall in a circular economy- Develop goals and targets for nutrient recovery from wastewater based on this nutrient management strategy (the Swedish inquiry on sludge management suggested a requirement of 60 % phosphorus recovery from wastewater treatment plants, this should just be the beginning and goals should also be set for other nutrients)- A larger interdisciplinary R&I effort regarding the recovery goals should be coordinated to analyze how the transition to a circular management of nutrients best can be accomplished on a systems level- Provide support to develop business models for optimal collaboration between different actors in different parts of the value chain and maximized resource efficiency- Technology development and demonstrations aligned with the holistic approach for circular management of nutrients in the suggested national nutrient management strategy

A paradigm shift to waste reuse has started in the wastewater sector with many experts calling for greater resource recovery, often facilitated by alternative solutions such as source separation. Source separation has been shown to be advantageous for improving treatment capacity, food security, and efficiency; yet these systems are still immature, considered risky by professionals and scarcely implemented. This study attempts to answer the question of why source separation is still marginalized by examining the Swedish experience with source separated wastewater from the perspective of Technology Innovation Systems (TIS) in order to identify obstacles and policy recommendations. Considering that source-separation is still in a development phase, the study found that source separation works moderately well within the on-site niche and that blackwater systems in general perform better than urine diversion. Knowledge development is found to be the weakest function. A major blocking mechanism is the weakness of interchange between knowledge development and entrepreneurial activity. Policy recommendations include: increased R&D; building networks and communication platforms; and establishing guidelines for technologies, legislation interpretation and organizational models.

Source separation of urine for recycling has been applied in small-scale and decentralized wastewater systems in Sweden for the past 25 years and for blackwater for pollution control even longer. The Swedish experience with source separating nutrient recycling systems is relatively well documented; however, few reports have specifically studied the potential for expansion of this practice. The aim of this study is to fill this knowledge gap by assessing the status of source-separating technologies in Sweden based on transition theory. This study uses a multi-level perspective to determine how ready the Swedish wastewater sector is for transitioning to alternative systems. Given the stability of the existing sewage wastewater regime, it seems unlikely that changes within the regime will lead to a quick and large-scale transition to source separation. Instead, the initiative must come from the niche itself, exploiting institutional cracks in the regime and opportunities from shifting trends in the landscape. If source separation is to be mainstreamed in Sweden, it will need to break into markets within the wastewater jurisdictions. In order to do so, further knowledge needs to be developed that will overcome glitches with immature technologies, uncertain legal conditions/status, investigate potential risks, and clearly define complementary system advantages. This may require the use of new perspectives that focus on holistic sustainable use of resources, including other nutrients than phosphorous, and taking into account global issues such as planetary boundaries and effects from climate change, such as water scarcity. This knowledge can then be used to establish guidelines, norms, and standards, as well as clarify the legislative structures that can support such a transition. There is also a strong need to improve knowledge dissemination regarding best-practices for implementing source-separation technologies and supporting organizational structures. Similarly, support for entrepreneurial activities within the niche needs to increase, not least through strengthening social networks and communication platforms.

The article presents input data that were used in Pericault et al. (2018) for life cycle impact assessment and total cost assessment of five technical alternatives for heat and water services provision in a suburban development in Sweden. The data consists of a list of environmental impacts (cumulative exergy demand of energy carriers - CExDe, global warming potential - GWP, abiotic depletion potential of elements - ADPE), costs, amortisation periods, lifetimes and output flows of the system processes composing the alternatives. The data was derived from values collected in lifecycle databases, environmental product declarations, scientific publications and personal communications with companies.

This study presents an integrated sustainability assessment of technical alternatives for water and heating services provision in suburban areas affected by a cold climate. Each alternative combines a drinking water supply, sewerage (gravity or low-pressure), pipe freeze protection (deep burial or shallow burial with heat tracing) and heating solution (district heating or geothermal heat pumps). An innovative freeze protection option was considered, in which low-temperature district heating (LTDH) is used to heat trace shallow sewer and water pipes. First, the performance of each alternative regarding seven sustainability criteria was evaluated on a projected residential area in Sweden using a systems analysis approach. A multi-criteria method was then applied to propose a sustainability ranking of the alternatives based on a set of weights obtained from local stakeholders. The alternative with a deep buried gravity sewer and geothermal heat pumps was found to have the highest sustainability score in the case study. In the sensitivity analysis, the integrated trench solution with a gravity sewer, innovative heat tracing and LTDH was found to potentially top the sustainability ranking if geothermal energy was used as the district heating source, or if the weight of the cost criterion increased from 24% to 64%. The study highlights the need for integrated decision-making between different utility providers as an integrated solution can represent sustainability gains.

The provision of a safe drinking water is of primary importance in society and a prerequisite for public health and economic development. In order to secure a long-term, safe and reliable supply of drinking water, and to ensure a comprehensive and integrated water planning, the development of regional water supply plans is increasingly requested in Sweden. To implement the plans, the water utilities, regional planners and politicians need to make several complex decisions and prioritize between multifaceted strategic measures. There are, however, very few decision support tools adapted for water supply management on the regional level to aid the decision makers. In order to achieve a sustainable drinking water supply, socio-economic effects need to be carefully considered. Hence, this study focuses on the development of a decision support framework for assessing socioeconomic effects of strategic decisions and alternative water supply measures by adapting costbenefit analysis (CBA) and economic valuation techniques to a long-term and regional perspective. The Gothenburg region, with its newly presented regional water supply plan, serves as a case study for which five alternative measures are evaluated: (1) centralization of water supply production; (2) centralization of water supply organization; (3) shift of the main raw water intake from the river Göta älv, a raw water source exposed to a high contamination risk, to the cleaner water of lake Vänern; (4) maximization of groundwater usage; and (5) increased number of raw water resources. The effects of each alternative are identified through literature reviews, stakeholder workshops and dialogues with experts and policy makers. To assess the non-market costs and benefits of the alternative strategies, the benefit transfer method is used for adapting estimates from national and international valuation studies to the Gothenburg region. The monetized costs and benefits are then used to set up a longrun CBA to identify the best strategy from a social welfare perspective. The net present values (NPVs) of the alternative measures are estimated for three different discount rates (constant rates of 1.4 % and 3.5 % as well as a declining discount rate) and two different time periods (ranging to 2050 and 2100). Uncertainties concerning the NPVs are analyzed by means of statistical simulation (Monte Carlo), accounting for uncertainties in input data. For the Gothenburg region, the results show the effect of the various strategies and give a direct guidance on which measures are most favorable from a cost-benefit perspective. The case study results are then used to design a general decision support framework that allows for non-market valuations and economic and ecological tradeoffs under uncertainty, a novelty on the regional scale. In conclusion, it is expected that the results of this study will provide decision makers and regional planners with a framework of tools to improve their ability to make well-informed decisions and to ensure the society a safe and reliable water supply for generations to come.

Small on-site sanitation systems are widely present in suburban and rural areas in many countries. As these systems often underperform and have an impact on receiving waters, understanding their overall sustainability is of interest for policy and decision-makers. However, the definition and estimation of indicators defining sustainability are challenging, as it is finding the methodological approach to combine qualitative and quantitative indicators into one comprehensive assessment. In this study, twelve indicators defined by environmental, economic, social, technical and health-related criteria were used to compare nine alternatives of on-site sanitation for single households. A non-compensatory method for multi-criteria decision analysis, ELECTRE III, was used for the assessment together with weights assigned to each indicator by a reference group. Several scenarios were developed to reflect different goals and a sensitivity analysis was conducted. Overall, the graywater-blackwater separation system resulted as the most sustainable option and, in terms of polishing steps for phosphorus removal, chemical treatment was preferred over the phosphorus filter, both options being implemented together with sand filters. Assessing the robustness of the systems was a crucial step in the analysis given the high importance assigned to the aforementioned indicator by the stakeholders, thus the assessment method must be justified. The proposed multi-criteria approach contributes to aid the assessment of complex information needed in the selection of sustainable sanitation systems and in the provision of informed preferences. © 2019 The Royal Society of Chemistry.

This report is written within the framework of the state's public inquiries M 2018:08, committee directive 2018:67 "Non-toxic and circular recycling of phosphorus from sewage sludge". One of the tasks in the directive is a task about mapping the technological development for phosphorus recovery, which this report highlights.

The methodology for answering the question has been to examine scientific articles published in recent years, and to review documentation from recent years' conferences, seminars and EU projects (completed and ongoing) in the field. Among the sources available on the internet, the German, Swiss and European phosphorus platforms have been the most important. A selection has been made of relevant processes, where the selection criteria are reported in the report. The starting point for recovering phosphorus is inside the waste water treatment plant (WWTP) where the sludge occurs. The reported processes have been subdivided on the basis of where in the process scheme they have their starting point, which is also the most common classification according to the literature.

The result is that the choice of method must be a balance of what one wants to achieve because no method meets all the wishes. A vast majority of processes meet the criterion of depollution, ie the degree of detoxification is very high, which is an important driving force for introducing them. The recycling potential of the processes is very variable, from 20 % of incoming phosphorus to the WWTP (usually struvite processes etc.) to just over 95 % of incoming phosphorus (usually thermal processes, e.g. biokol and extraction from ash), since it involves the whole sludge stream. In order to achieve a high recovery rate when internal processes are applied, it is also required that the phosphorus in the remaining dewatered sludge is recycled.

Only one category of processes is assessed to be fully developed, namely the struvite processes. All other processes are considered "new technology" or "promising innovations". Most of the internal processes in WWTP do not fit well in Sweden because most Swedish WWTPs use chemical precipitation of phosphorus instead of biologically.

An important aspect from the system- and economic point of view is in what form the phosphorus comes out of the process, which is highly variable for the processes studied. The processes in which phosphorus comes out in a form known to the agriculture (or industry) are considered to have the greatest potential to be viable in the long term. It has been difficult to obtain costs for introducing the studied processes, this because the processes are under development. It is often pointed out that phosphorus recovery processes are very expensive, but compared to today's costs that WWTPs has to get rid of the sludge, it is unclear how large the cost difference actually becomes.

The report also highlights the environmental impacts from a life-cycle perspective. The general conclusion is that it is difficult to obtain knowledge because most of the processes are under development, and that it is difficult to draw any clear results from the analyzes that have been fulfilled.

Three different ways of taking care of the entire sludge flow have been identified; bio-coal, ash and ash extraction. The first means that the entire sludge amount is dried and pyrolyzed and the remainder is a bio char which should be regarded as a carbon-sink and a long-term phosphorus source. The second way is to burn ash and direct spread of this ash. The third way involves the extraction of phosphorus from this ash in different ways and here there are three methods of this type that are at approximately the same level of development. Two other methods that are regarded as promising innovations are about HTC processes (hydrothermal carbonization) and extraction using CO2. Assessed advantages and disadvantages for these and other categories of processes can be found in the report.