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Phosphorus (P) in societal waste streams can be recycled and used as recycled P fertilisers (RPFs). When developing new technologies for P recycling, life cycle assessment (LCA) can be used to assess their environmental impact and support environmentally friendly decisions. In LCA calculations, inventory factors describe, for example, the emissions, resource requirements and potential substitution of products. The Phosphorus Life Cycle Inventory (PLCI) model is a tool for estimating such inventory factors for the use of RPFs. The main objective of this study was to develop the PLCI model from its previous parameterisation for Denmark to make it applicable to all countries and regions of the EU. This was undertaken by considering parameters that describe regional conditions affecting the loss of P, crop P uptake and potential mineral fertiliser substitution. Such parameters include soil type, soil P status, soil erosion, groundwater leaching, crop types, productivity and crop P concentrations. Several RPFs were incorporated into the model, including coefficients describing the partitioning to the labile, plant-available P fraction. To illustrate the applicability of the model, a case study was performed. Applications of RPFs were modelled in the Copenhagen region in Denmark and the Piedmont region in Italy. The higher soil erosion rate in Piedmont resulted in over six times greater P loss than in Copenhagen. The difference in P fertilisation practice between the regions had a strong impact on the mineral fertiliser substitutions. The results point to the importance of defining the fertilisation regime of the region being modelled, and this is now possible with the new, more dynamic version of PLCI. In conclusion, the new PLCI 2.0 model provides a dynamic tool for LCA practitioners to estimate region-specific inventory factors for RPFs. The model is relatively easy to use and captures differences between fertilisers with varying P availability and between applications in different regions of the EU. [Display omitted] • A life cycle inventory model for recycled P fertilisers was developed. • Regionalisation allowed differentiation in fertilisation effects between regions. • The model was applied to case studies in Denmark and Italy. • Higher soil erosion in Piedmont caused six times higher P loss than in Copenhagen. • The model captured differences between fertilisers with varying P availability. [ABSTRACT FROM AUTHOR]

Use of recirculating aquaculture systems (RAS) to grow fish is on the rise. Fish feed typically contains 25–60% protein and is the only significant input in RAS. Fish recover 20–30% of the applied feed as biomass, and the unassimilated nitrogen is released into the water, mainly as ammonia, which is toxic to fish. Nitrification is the most common treatment practice, converting ammonia to the less toxic nitrate, and nitrogen removal is achieved by either water exchange or denitrification. The aim of this study was to develop and test a novel approach to remove nitrogen based on a microaerophilic assimilation side-reactor. In the suggested system, fish solid waste and dissolved nitrogen are assimilated into protein-rich microbial biomass, which has the potential to partially offset fish feed input. Initially, a theoretical model based on the system's nitrogen mass balance was established. Then, an intensive pilot-scale RAS was constructed, growing ∼50 kg fish/m3. The system consisted of a fish tank, solids filter, and microaerophilic assimilation reactor based on activated sludge treatment. Intrinsic solid waste and wheat-flour waste were used as carbon source. After a trial run of about 2.5 months, the RAS was tested for 101 days. Average total ammonia nitrogen, nitrite, and nitrate removal were 89.1, 69.4 and 100%, respectively. Of the introduced solids, over 82% were lost as carbon dioxide by respiration, 11.7% were recovered as microbial biomass and 6.5% as fish biomass, and only 0.6% remained in the water. Biomass organic content was similar to aquafeed and nitrogen content was equivalent to 40% crude protein. Daily energy demand for the system's designed capacity of 80 kg/m3 would result in a low energy consumption of 7.72 kW h/kg fish. Overall, a novel concept for sustainable production in intensive aquaculture was developed and successfully demonstrated in a pilot-scale RAS. Image 1041268 • A novel sustainable RAS based on assimilation side-reactor was modeled and tested. • TAN and NO 2 concentrations in the fish tank were < than 0.89 and 0.1 mg/L. • Low feed conversion ratio and energy consumption were demonstrated. • The collected biomass (biofloc) has 40% crude protein similar to aquafeed. [ABSTRACT FROM AUTHOR]

European agriculture is a large importer of nutrients in the form of chemical fertilizers. Additionally, countries with livestock-intensive farming face problems with disposal of nutrients in animal manure. The availability of chemical fertilizers has changed farmers' past dependence on manure. Nowadays, despite its nutrient content, manure is sometimes considered as a waste product. However, if the characteristics of manure and other waste streams could be enhanced through processing, it could be transformed into an alternative bio-based fertilizer recycling the nutrients within the farming sector. This would also create opportunities for nutrient exchange between different European regions. However, a key question is what is needed for farmers to accept these products as replacements for their current chemical fertilizer use? In this paper, key attributes determining the acceptance of alternative bio-based fertilizer products are identified. Based on the identified attributes, a discrete choice experiment was designed to reveal farmers' preferences and Willingness-To-Pay for these attributes. Identical experiments were conducted in seven different European countries. The results indicate that farmers from the different countries have common preferences for concentrated products that have certainty in the nitrogen content and at a lower price than chemical fertilizer. Other attributes such as the presence of organic carbon, hygienization of the product and fast release of nutrients were only statistically significant in some countries. The results imply that a bio-based fertilizer similar to chemical fertilizers could be sold at around 65% of the price of mineral fertilizer. Additionally, we show which attributes industry should take into consideration when estimating the demand for new bio-based fertilizer products. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of food waste within urban areas can generate decentralised renewable energy and support community enterprise activities, thereby contributing to closing the waste-energy-food loop. However, widespread uptake of small-scale, urban anaerobic digestion networks is limited by economic costs and the safe disposal of surplus digestate. This paper uses an interdisciplinary approach to assess the feasibility of anaerobic digestate management through the installation of hydroponics or algae cultivation systems, based on a case study of a micro anaerobic digestion system in London, England. Results show that installing a dewatering sifter together with a hydroponics system is a technically and economically feasible option for digestate enhancement in the urban environment. Its installation is, however, not currently justified for the system under consideration due to cost, regulatory, spatial, and contextual constraints identified using actor-network analysis. Nevertheless, if regulatory and wider contextual issues are accommodated, and more than 30 L of digestate are produced daily, a dewatering and vertical hydroponic system could result in a profit of approximately £100,000 over 10 years. While the microalgal system was also able to upgrade digestate, at present productivity is too low and the capital cost of photobioreactor technology is prohibitively expensive. This underlines the need for technical improvements and low-cost enhancement options to achieve justifiable paybacks until regulatory reforms and the wider economic situation are more favourable to anaerobic digestion treatment within cities. [ABSTRACT FROM AUTHOR]

Boron (B) fertilizers are essential for global crop production. Sustainable B use demands a higher efficiency of B fertilizers through controlled B release and an enhanced B recycling from secondary sources, e.g. B-impregnated cellulose fiber insulation (CFI) waste. In this study, thermochemical treatments based on combustion and pyrolysis were investigated for processing CFI waste into a slow-release B fertilizer. Hot-water extractions of obtained materials confirmed that slow-release properties were achieved, and material characterization with XRD, FTIR and 11B-NMR showed that these were largely the result of formation of sparingly soluble Ca–B phases. A seedling toxicity test with fodder rape demonstrated the benefit of this slow-release B in comparison with conventional soluble B to circumvent toxicity, suggesting potential for B application via seed coatings. Finally, a fertilization trial with fodder rape and poppy seed showed that most slow-release B compounds were equally effective as soluble B at recommended B doses, while slow-release B can still benefit from reduced B leaching losses. [Display omitted] • Thermochemical processing of B-rich cellulose fiber insulation (CFI) was tested. • Obtained combustion and pyrolysis products had slow-release B characteristics. • Slow-release B was largely the result of formation of sparingly-soluble Ca–B phases. • B toxicity to plants could be avoided using treated CFI instead of soluble B. • In a plant fertilization trial, treated CFI was equally effective as soluble B. [ABSTRACT FROM AUTHOR]

This study aimed to develop a regional nutrient demand-based approach to assess the potential use of digestate nutrients from a planned biogas plant investment as a part of a regional circular economy concept. The assumed biogas plant is expected to treat urban wastes; biowastes (23,500 t/y) and sewage sludges (120,000 t/y) from the Tampere region, Finland (total population of 500,000). The calculation of the regional nutrient balance was based on the fertilizable crop areas, fertilization regimes and biomass nutrient amounts, with an assumption that livestock manures were primarily utilized in crop production. Subsequently, a Geographic Information System (GIS)-based methodology was applied to evaluate the transportation distances of nutrients from the biogas plant to the closest crop fields. As a result from the presented approach, livestock manure covered 41% and 12% of the phosphorus (P) and soluble nitrogen (N) need of the studied region. There was a residual potential for the regional utilization of biogas plant nutrients, which together with the livestock manure accounted for 50% of P and 15% of soluble-N need. Transportation of nutrients up to 40 km from the biogas plant is necessary if all nearby fields receive the waste-based nutrients, while the distance increased to 66 km if 30% of the local farmers are willing to use the nutrients. The approach presented in this study acts as a tool for planning nutrient cycles, which can be used to sustainably manage the regional nutrient flows when planning a new biogas plant investment. [ABSTRACT FROM AUTHOR]

Cycling of nutrients, such as phosphorus (P) and nitrogen (N), is essential for all life: Nutrients are crucial for securing societies' food systems and valuable raw materials for industrial processes. Recycling nutrients from various side and waste streams instead of virgin nutrients has attracted considerable interest in the society, particularly as geopolitical and epidemic issues have caused many nations to reconsider how they ensure flows of critical resources by increasing the Circular Economy (CE) principles. This study examines what drivers and barriers catalyze nutrient circulation in national settings, requiring diverse actors to support intentional nutrient recycling. By taking multidisciplinary and ecosystem approaches, we examine diverse sociotechnical drivers and barriers and the actor ecosystem involved. We conduct an extensive qualitative case study on nutrient circulation (P and N) in a Finnish context, analyzing over 150 documents and interviewing over 20 diverse actors (from diverse companies through ministries to farmers) involved in nutrient recycling, from biowaste through agricultural biomasses and sludge from municipal wastewater treatment plants. Our study 1) generates an ecosystem actor map uncovering diverse actors enabling nutrient recycling in society; and 2) exposes technological, business, organizational, regulatory, linguistic, visual, and psychological drivers and barriers shaping nutrient circulation. It explains the sociotechnical preconditions for different actor/stakeholder groups to adopt and advocate circular economy (CE) principles for nutrient recycling, which are generalizable to other critical resources. The study contributes to CE research and advises practitioners by providing a comprehensive catalyst toolbox to advance nutrient circulation and facilitate its acceptability and diffusion. [Display omitted] • Qualitative study analyzes drivers/barriers for recycling of critical resources, nutrients. • "Ecosystem" is applied as a metaphor for a multi-actor constellation enabling recycling. • Key actors for nutrient recycling ecosystem vary from farmers and businesses to policymakers. • Catalysts are technical, business, organizational, regulatory, linguistic, visual, and psychological. • A framework is developed for sociotechnical drivers advancing circular economy diffusion. [ABSTRACT FROM AUTHOR]

Efficient use and recycling of resources by utilizing nutrients of waste water and CO 2 from flue gases are considered through comparing two conceptual systems: a conventional small scale waste water treatment plant (base case) and a waste water treatment plant combined with algae cultivation unit (algae case). The used algae case concept is based on interviews of experts working with algae cultivation in Finland. Hotspots related to the algae case are assessed from environmental perspectives. According to model calculations, in high latitudes effective algae production may be achieved, although the areal production rates are very low in winter. In the algae case concept nutrients of waste water can be more effectively recycled using bio-based chitosan as flocculant. Also energy is produced in the biogas production plant, which increases the resource recycling of the algae case. When considering the energy balance, a positive net energy ratio (NER) >1 is possible to achieve with maximum methane production potential of algal biomass. [ABSTRACT FROM AUTHOR]

In a context of climate change and circular economy, it is fundamental to produce animal manure-based fertilizers attractive to farmers who are reluctant to use heterogeneous materials, poorly characterized and with unbalanced nutrient contents, namely N:P ratios different from plant requirements. Hence, the aim of the present study was to assess the potential of different treated and non-treated animal manures to produce tailor-made manure-based fertilizers with known N:P ratios. Seven manures were considered: cattle, caprine and poultry solid manures, two contrasting cattle slurries and two contrasting swine slurries. Slurries were further treated by solid-liquid separation, acidification, and acidification followed by solid-liquid separation. Raw and treated manures were fully characterized to assess the effect of manure type and treatment on their nutrient contents and N:P ratios, to incorporate them in manure-based fertilizers with selected N:P ratio. The present results were essential to support the manure-based fertilizer production and identify which materials could be considered: it appears clearly that the pig slurry with all stages of production and the correspondent liquid fraction cannot be used due to their low nutrients content. It was shown that the solid fractions rich in P and with a N T :N–NH 4 + ratio close to 1 are an excellent material to prepare manure-based fertilizers. Acidification, combined with solid-liquid separation, produced a liquid fraction rich in both N and P and with a N T :P T ratio close to 1, with the additional benefit of a slow N-release material. Some of the manures or sub-products obtained after treatment provided the usual N:P ratio required by farmers and could be used directly as substitutes of mineral fertilizers. Nevertheless, the blending of some of these materials has a stronger potential to the production of specific manure-based fertilizer. • Animal species and manure management influence manure composition and N:P ratio. • Slurry treatment is a good tool to modify N:P ratio of manure. • Combination of raw and/or treated manures allow producing manure based fertilizers. • Manure based fertilizers can have N:P ratio similar to mineral fertilizers.. [ABSTRACT FROM AUTHOR]

Abstract: Several ongoing projects are harvesting maritime biomass from the Baltic Sea for eutrophication mitigation and utilisation of the recovered biomass. Some of this biomass comprises common reed (Phragmites australis), one of the most widespread vascular plants on Earth. Reed utilisation from eutrophied coastal areas needs to be evaluated. Therefore, a system analysis was performed of reed harvesting for biofuel and biofertiliser production. The specific objectives of the analysis were to: investigate the methane yield associated with anaerobic co-digestion of reed; make a primary energy assessment of the system; quantify Greenhouse Gas (GHG) savings when a fossil reference system is replaced; and estimate the nutrient recycling potential of the system. The results from energy and GHG calculations are highly dependent on conditions such as system boundaries, system design, allocation methods and selected indicators. Therefore a pilot project taking place in Kalmar County, Sweden, was used as a case study system. Laboratory experiments using continuously stirred tank reactor digesters indicated an increased methane yield of about 220 m3 CH4/t volatile solids from co-digestion of reed. The energy balance for the case study system was positive, with energy requirements amounting to about 40% of the energy content in the biomethane produced and with the non-renewable energy input comprising about 50% of the total energy requirements of the system. The net energy value proved to be equivalent to about 40 L of petrol/t reed wet weight. The potential to save GHG emissions compared with a fossil reference system was considerable (about 80%). Furthermore an estimated 60% of the nitrogen and almost all the phosphorus in the biomass could be re-circulated to arable land as biofertiliser. Considering the combined benefits from all factors investigated in this study, harvesting of common reed from coastal zones has the potential to be beneficial, assuming an appropriate system design, and is worthy of further investigations regarding other sustainability aspects. [Copyright &y& Elsevier]

The study developed a holistic approach based on the thermal digestion (TD) technique for the rapid conversion of solid organic waste (SOW) into nutrient-rich organic fertilizer. The effect of digestion temperatures (110oC–170 °C) on the weight reduction from the SOW and the availability of the nutrients were thoroughly investigated. The potential weight reduction of 75.2% was achieved at a temperature of 150 °C for 135 min, as illustrated by response surface methodology (RSM). Scanning electron microscope (SEM) study was carried out to analyze the changes into surface morphology of the sample before and after the digestion. Fourier transform infrared (FTIR) analysis was conducted to study the mineralization process. Thermogravimetric-Differential thermal analysis (TG-DTA) was conducted to study the thermal decomposition behavior of the untreated and digested SOW. The digested SOW resulted high nutrient-rich end product (N-2.08 ± 0.01%, P-0.42 ± 0.00%, & K-1.65 ± 0.06%), which have potential to be used as organic fertilizer. Fertilizing potential of the digested SOW complied with the delineated norms of the organic fertilizer given by the Fertilizer Association of India (2019). Maturity and phytotoxicity of the digested SOW were explored on the basis of C:N ratio (18.07 ± 0.17), humification index (3.43 ± 0.02), heavy metals content, as well as through seed germination index (>90%). The proposed technology may lead to the paradigm shift in waste management and provides an efficient alternative for the recycling of nutrients. [Display omitted] • A cleaner technology for sustainable management of solid organic waste. • Rapid conversion of solid organic waste into nutrient rich organic fertilizer. • 150 °C was found to be the most optimum temperature for thermal digestion. • Phytotoxin free organic fertilizer suitable for agricultural sustainability. [ABSTRACT FROM AUTHOR]

The globally growing demand to produce more food with fewer inputs, less energy, and lower greenhouse gas (GHG) emissions challenges current agricultural practices. Recycled fertilizers made of various side streams and types of biomass have been developed mainly to improve nutrient recycling in food systems. However, the knowledge of the impacts of different recycled fertilizers on GHG emissions and energy use is lacking. There is also a need for developing environmental assessment methods for quantifying the impacts of recycling processes, particularly in terms of choosing reasonable methods for co-product allocation. The aims of this study were to address the above mentioned research gaps by i) assessing energy use and GHG emissions of various recycled fertilizers, ii) comparing the recycled fertilizers with mineral fertilizers, and iii) comparing the impacts of using different co-product allocation methods for the recycled fertilizers. Attributional Life Cycle Assessment (LCA) was used for estimating energy use and GHG emissions of recycled fertilizers, including ammonium sulfate, biogas digestate, and meat and bone meal, using kg of nitrogen in the fertilizers as a functional unit. In addition, the energy use and GHG emissions of oat production when using the recycled and mineral fertilizers were quantified. The data were obtained from field experiments, LCA databases, published literature, and fertilizer companies. The life-cycle energy consumption and GHG emissions of recycled fertilizers were found to be lower than that of mineral fertilizer, but also differences between recycled fertilizer products were notable. The biggest differences between fertilizers occurred in manufacturing and transportation. However, this conclusion is highly sensitive to several decisions, such as data sources and LCA methods used. Handling the raw materials of recycled fertilizers as by-products instead of residues adds burdens from primary production to fertilizers. Also handling the materials as waste increases the impacts due to burdens from the recycling process. Since the raw materials of fertilizers have only little economic value, applying economic allocation results to significantly lower impacts than mass allocation. Consequential LCA studies would be needed to improve the understanding of the wider impacts of recycled fertilizers, e.g. considering the benefits of avoided waste management processes. • No statistically significant differences in yields between the fertilizers. • Lower energy use and emissions with recycled than mineral fertilizers. • Notable differences in emissions and energy use between recycled fertilizers. • Effect of data sources and allocation methods were considerable. [ABSTRACT FROM AUTHOR]

The present study focused on the integration of the non-sterile conversion of food waste (FW) into hydrogen (H 2) through dark fermentation with the subsequent electricity generation in a proton-exchange membrane fuel cell (PEMFC), and the assessment of the global warming potential (GWP) of the process. The acidogenic conversion of FW performed in continuous operation for 16 days produced 45.6 ± 0.1 L H 2 at an average H 2 productivity of 6.1 ± 1.3 L L−1 d−1. Butyric and acetic acid were simultaneously produced at average concentrations of 3.6 ± 0.5 and 1.6 ± 0.3 g L −1, respectively. The carbon dioxide (CO 2) from biogas product was sequestered by reaction with sodium hydroxide and the resulting H 2 -rich stream was fed to a PEMFC, producing 1.7 Wh L−1 H 2. The process scale-up was simulated based on the bench-scale conversion yields and was used to assess the GWP. Two of the developed scenarios, which considered the reuse of the fermentation sludge as nitrogen source in the acidogenic fermentation, diminished the GWP emissions by 63.8% and 64.3% when compared to the default condition. In the best-case scenario, an annual average of 0.18 t of CO 2 per t of FW separately collected was generated. • Acidogenic conversion of food waste (FW) for 16 days produces 6.1 ± 1.3 L H 2 (L d)−1. • The H2 yield reaches 74.9 ± 15.8 L kg−1 vs in continuous stirred tank reactor. • A proton exchange membrane fuel cell fed with the bioH2 generates 1.7 Wh L−1 H 2. • Alternate industrial scale scenarios are compared using the consequential approach. • Best-case biorefinery emits annually 0.18 t CO2 (t FW)−1. [ABSTRACT FROM AUTHOR]

Technologies to remove nitrogen from wastewater are employed to preserve drinking water and prevent environmental damage. Nitrification/denitrification and partial nitrification-anammox are two accepted nitrogen removal techniques for wastewater treatment plants. These processes require energy for aeration and can release fugitive greenhouse gases in the form of nitrous oxide. Electrodialysis could potentially be used as an alternative to remove ammonium from waste streams, but previous experimentation has concluded that concentrate streams experience rapid scaling and fouling of membranes. This analysis compiles literature values to compare the state-of-the-art of municipal nitrogen removal to the new electrodialysis technique on an economic basis. Results show that nitrogen removal and recovery by electrodialysis is estimated to lower both initial capital costs and subsequent operation costs than traditional N removal technologies. Image 1 • Modeled electrodialysis ammonium recovery on municipal sludge digester reject water. • Developed optimization method based on stack cost and influent conditions. • Electrodialysis estimated to be less expensive than existing N removal technologies. • Cost differences come primarily from inexpensive and compact installation. [ABSTRACT FROM AUTHOR]

Buildings in cities represent potential point sources of human excreta-derived nutrients, while agricultural land in (peri)urban areas demand nutrients as fertilizers. Here we present a new geographic information system (GIS)-based modelling tool, Resource Dynamo, that optimizes the allocation of excreta-derived nutrients from buildings in cities to nearby agricultural fields. The model minimizes the number of supply sites needed to match the demand by prioritizing sites with the highest nutrient supply, i.e. the hotspots. Furthermore the model delineates exact transport routes between the discrete supply and demand sites. The transport distances are minimized as transport costs are a key factor for economic viability of nutrient management. The high resolution of the model allows it to function as a decision-support tool for bringing cyclic nutrient management into practice. To disclose the potential of the model, we used it to match phosphorus supply in human-derived urine with phosphorus demands from agricultural fields within the municipality of Amsterdam on a temporal scale of 1 year. • Geospatial transport distance optimization between nutrient supply and demand sites. • In Amsterdam, 38% of phosphorus supply from human urine covers agricultural demand. • Average transport distances between supply and demand sites were under 11 km. • Visualization with Resource Dynamo can support decision-making towards nutrient cycling. [ABSTRACT FROM AUTHOR]

Previous and current agricultural practices have contributed to environmental pollution, which is further affecting food security, human health, and climate. Yet, agriculture cannot be eliminated, because, of its promising role in ending hunger, reducing poverty, improving nutrition, and achieving food security in low-middle income countries. Hence, there is a need for shift from 'unclean' practices to sustainable practices. Similarly, differences in pollution, among nations call for regional changes or intervention in agri-food practices to reduce global pollution. These practices are essential for African and Asian countries. Of the many methods proposed in this review, localized technology improvement and globalized sustainable intensification are of high impact models having the potential of mitigating greenhouse gases up to an extent of 30%. Various methods of achieving these measures include, but not limited to, the shift in management systems of crop and livestock production, encouraging agriculture and veterinary practices with less environmental impact and high adaptation, enabling nutrient recycling or recovery, resource-use efficiency, mitigation of nitrous oxide and methane from soil, implementation of integrated farming system and insect farming. Government agencies along with agri-food producers, processors, and farmers must be ready to change their current agricultural practices by adopting new methods. The review conclude that the sustainable agricultural production is possible through the use of low-priced local resources that are capable of increasing soil carbon storage, thus combating the pollution in countries with a transition economy. • Fungi and biochar can mitigate greenhouse gasses, recover nutrients and be used as feed additives. • Water hyacinth and seaweed can recover nutrients from wastewater and used as feed or fuel. • Carbon fiber reduced nitrous oxide emission by 85% in swine wastewater treatment. • Insect farming can be used for converting agricultural waste to high-quality protein for livestock. • Integrated farming can increase value derived per unit of water and other resource-input. [ABSTRACT FROM AUTHOR]