Fertilizer Production Research Articles

Consequential LCA of NPK fertilizers from microbial, animal, plant, and mineral origin highlights resource constraints and environmental impacts

The production and use of mineral fertilizers lead to severe environmental impacts, therefore initiatives such as the European Green Deal promote organic farming and nutrient circularity. However, many organic fertilizers (those containing organic carbon and nutrients of exclusively biological origin) face constraints due to resource availability, and it is paramount to understand their environmental impacts to prevent unforeseen effects. This study employed a consequential life cycle assessment (LCA) to compare the environmental impact of mineral fertilizer to three types of organic fertilizers: animal-, plant-, and innovative microbe-based, considering market constraints and marginal suppliers. Organic fertilizers were complemented with mineral products to yield NPK compound fertilizers containing 1 t of nitrogen, 0.44 t of phosphorus, and 0.83 t of potassium (multi-substance functional unit). The findings reveal that 9 out of the 17 studied organic fertilizers are constained products, and that their demand is met through the supply of mineral fertilizers, soybean meal, and maize or barley grain. Consequently, for the transition to a circular and organic agrifood system, the focus should shift toward untapped resources like microbial fertilizers sourced from food and beverage industry wastewater, and sewage sludge. Constrained markets vary with time and geographical location, emphasizing the importance of context-specific decision-making. The impact of mineral fertilizers is relatively low across impact categories, but the gap between them and energy-intensive organic fertilizers narrows in an industrial symbiosis scenario where waste heat is available. An additional assessment of soil organic carbon estimated the contribution of organic fertilizers to the “4 per 1000" initiative's goal for soil carbon storage. Organic fertilizer application alone only achieves this goal in one scenario (rapeseed meal), but combining it with other management practices like crop rotation offers a promising strategy. The scenario that included fertilizer transport showed the potential for reduced environmental impacts by applying locally available by-products as organic fertilizer instead of imported mineral fertilizers. Overall, the results call for caution when transitioning from mineral to organic fertilizers as their availability and environmental impact are not self-evident.

Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst.

Ammonia (NH3) is a critical chemical for fertilizer production and a potential future energy carrier within a sustainable hydrogen economy. The industrial Haber-Bosch process, though effective, operates under harsh conditions due to the high thermodynamic stability of the nitrogen molecule (N2). This motivates the search for alternative catalysts that facilitate ammonia synthesis at milder temperatures and pressures. Theoretical and experimental studies suggest that circumventing the trade-off between N-N activation and subsequent NHx hydrogenation, governed by the Brønsted-Evans-Polanyi (BEP) relationship, is key to achieving this goal. Recent studies indicate metal phosphides as promising catalyst materials. In this work, a comprehensive density functional theory (DFT) study comparing the mechanisms and potential reaction pathways for ammonia synthesis on Fe(110) and Fe2P(001) is presented. The results reveal substantial differences in the adsorption strengths of NHx intermediates, with Fe2P(001) exhibiting weaker binding compared to Fe(110). For N-N bond cleavage, multiple competing pathways become viable on Fe2P(001), including routes involving the pre-hydrogenation of adsorbed N2 (e.g., through *NNH*). Analysis of DFT-derived turnover rates as a function of hydrogen pressure (H2) highlights the increased importance of these hydrogenated intermediates on Fe2P(001) compared to Fe(110) where direct N2 dissociation dominates. These findings suggest that phosphorus incorporation modifies the ammonia synthesis mechanism, offering alternative pathways that may circumvent the limitations of traditional transition metal catalysts. This work provides theoretical insights for the rational design of Fe-based catalysts and motivates further exploration of phosphide-based materials for sustainable ammonia production.

THE MAKING OF LIQUID ORGANIC FERTILIZER FROM GINGER WASTE BY HIGH SCHOOL STUDENTS AT AL HIDAYAH DLANGGU MOJOKERTO

Introduction: After the production of "Hidayah" ginger drinks, there has been a significant accumulation of ginger waste around AL Hidayah High School. This waste has led to unpleasant odors, attracting flies and creating an unsightly environment. This community service program aims to repurpose ginger waste into something beneficial, such as liquid organic fertilizer. Methods: The community service project employed an educational approach followed by practical sessions in producing organic liquid fertilizer through a biorefinery system. All students at AL Hidayah High School in Dlanggu Mojokerto were involved in this activity, which took place on May 25, 2023. Results: The outcome of this initiative was the production of organic liquid fertilizer using biorefinery methods. Conclusion: The liquid organic fertilizer derived from ginger waste through biorefinery methods has the potential to mitigate several associated issues. It proves to be advantageous for the local community, serving as a plant nutrient and potentially contributing to the school's economic growth if produced in sufficient quantities for market distribution. Furthermore, this endeavor nurtured creativity and entrepreneurial skills among the students.

A Study on the Valorization of Rice Straw into Different Value-Added Products and Biofuels

This work depicts that rice straw (RS), which is one of the major lignocellulosic wastes all over the world and causing many environmental problems, has considerable amounts of protein, ash, macronutrients, and micronutrients of approximately 11.38%, 16.77%, 2.27 mg/kg, and 771.9 mg/kg, respectively; besides, a C/N ratio of 15.18, a total N, P2O5, and K2O content of 1.85%, and a considerably low concentration of undesirable heavy metals and silica of approximately 77.69 mg/kg and 109 mg/kg are also present, which recommends its applicability as a precursor feedstock for the production of organic fertilizer and animal fodder. The batch solid-state fermentation (SSF) of RS by Trichoderma longibrachiatum DSMZ 16517 produced considerable amount of total reducing sugars (TRS) of approximately 339.2 mg TRS/g RS under the optimum operatic conditions of 20% (w:v) substrate concentration, pH 7, 1% inoculum size, a 9-day incubation period, and 30°C incubation temperature. The readily available and cost-effective agroindustrial waste, sugarcane molasses, proved to enhance the fungal biomass growth and (hemi) cellulolytic enzymes activities. The inoculated RS-SSF batch process with T. longibrachiatum precultured on 10% molasses enhanced the (hemi) cellulolytic enzymatic activities and TRS production rate by approximately 5.82 and 3.8 folds, respectively, relative to that inoculated by T. longibrachiatum precultured in the conventional potato dextrose broth medium. The separate hydrolysis and fermentation processes by different yeast strains Candida tropicalis DSM 70156, C. shehatae ATCC 58779, and Saccharomyces cerevisiae ATCC 64712 revealed an efficient bioethanol yield and productivity that ranged between 0.36 and 0.38 g/g sugars and 0.22 and 0.23 g/L/h, respectively, with concomitant competent fermentation efficiencies that ranged between 48.35% and 51.25%. The proximate analysis of rice straw before and after fungal hydrolysis proved calorific values of approximately 15.8 MJ/kg and 16.05 MJ/kg, respectively, recommending their applicability as primary and secondary solid biofuels. Thus, this study proved the waste prosperity of RS for environmental opulence and sustainability.

Microbiology of post-fermentation leachate

Using post-fermentation leachate as fertilizer is a good alternative and solution to the problem of waste at wastewater treatment plants and contains the principles of sustainable development. Leachate from anaerobic treatment of sewage sludge contains valuable elements such as phosphorus, nitrogen and potassium, which can improve soil properties. The production of liquid fertilizer minimizes the negative impact of leachate on the main biological stream in the WWTP and improves the energy efficiency of the entire wastewater treatment system. This transfers into the operating costs of the facility. When thinking about the agricultural use of digestion leachate and its introduction into the environment, a very important issue is its microbiological contamination. The purpose of the conducted research was to determine the microbiological quality of digestion leachates from municipal wastewater treatment plants and to determine the parameters of their hygienization. The number of bacteria in raw leachate is indicative of a sanitary risk in the case they are used in agriculture as fertiliser. Heating the leachate at 60°C for 15 minutes produces an effect comparable to that achieved by heating the leachate to 70°C. The sonication process itself did not affect the better temperature effect. Heating the leachate for 20 minutes after prior sonication for 20 minutes does not result in the complete elimination of microflora.

RAW MATERIAL BASE FOR THE PRODUCTION OF PHOSPHATE FERTILIZERS IN GEORGIA

For the full functioning of agriculture a significant place is occupied by its provision of fertilizers. The development of the chemical industry in the world has driven the development of production of minerals and especiatly nitrogen fertilizers. Similar situation in Georgia. 99% of the fertilizers produced in the country is nitrogen fertilizers. As for phosphorus and potassium fertilizers, they are almost not produced in the country and the need for them is met by imported products. Analisis of mineral resources of Georgia shows that the country has sulficient resources for the development of the fertilizers industry. The resources base of phosphorites is being considered, its geological existing estimates are being considered and the necessary additional research is being considered in order to develop new technological solutions the development of the production of phosphorus and complex fertilizers. Keywords: Fosforite, Fertilizers, Production, Rav material, Ore, Industry.

Sustainable transition in the fertilizer industry: alternative routes to low-carbon fertilizer production

Sustainable transition in the fertilizer industry: alternative routes to low-carbon fertilizer production

Combining anaerobic digestion slurry and different biochars to develop a biochar-based slow-release NPK fertilizer

In this research, we developed a biochar-based fertilizer using biogas slurry and biochar derived from lignocellulosic agro-residues. Biogas slurry was obtained through the anaerobic digestion of the organic fraction of municipal solid waste (fresh vegetable biomass and/or prepared food), while biochars were derived from residues from quinoa, maize, rice, and sugarcane. The biochar-based fertilizers were prepared using an impregnation process, where the biogas slurry was mixed with each of the raw biochars. Subsequently, we characterized the N, P and K concentrations of the obtained biochar-based fertilizers. Additionally, we analyzed their surface properties using SEM/EDS and FTIR and conducted a slow-release test on these biochar-based fertilizers to assess their capability to gradually release nutrients. Lastly, a bioassay using cucumber plants was conducted to determine the N, P, and K bioavailability. Our findings revealed a significant correlation (r > 0.67) between the atomic O/C ratio, H/C ratio, cation exchange capacity, surface area, and the base cations concentration with N, P, and/or K adsorption on biochar. These properties, in turn, were linked to the capability of the biochar-based fertilizer to release nutrients in a controlled manner. The biochar-based fertilizer derived from corn residues showed <15 % release of N, P and K at 24 h. Utilization of these biochar-based fertilizers had a positive impact on the mineral nutrition of cucumber plants, resulting in an average increase of 61 % in N, 32 % in P, and 19 % in K concentrations. Our results underscore the potential of biochar-based fertilizers in controlled nutrient release and enhanced plant nutrition. Integration of biochar and biogas slurry offers a promising and sustainable approach for NPK recovery and fertilizer production in agriculture. This study presents an innovative and sustainable approach combining the use of biochar for NPK recovery from biogas slurry and its use as a biochar-based fertilizer in agriculture.

Carbon footprint of synthetic nitrogen under staple crops: Afirst cradle-to-grave analysis.

More than half of the world's population is nourished by crops fertilized with synthetic nitrogen (N) fertilizers. However, N fertilization is a major source of anthropogenic emissions, augmenting the carbon footprint (CF). To date, no global quantification of the CF induced by N fertilization of the main grain crops has been performed, and quantifications at the national scale have neglected the CO2 assimilated by plants. A first cradle-to-grave life cycle assessment was performed to quantify the CF of the N fertilizers' production, transportation, and application to the field and the uses of the produced biomass in livestock feed and human food, as well as biofuel production. We quantified the direct and indirect inventories emitted or sequestered by N fertilization of main grain crops: wheat, maize, and rice. Grain food produced with N fertilization had a net CF of 7.4 Gt CO2eq. in 2019 after excluding the assimilated C in plant biomass, which accounted for a quarter of the total CF. The cradle (fertilizer production and transportation), gate (fertilizer application, and soil and plant systems), and grave (feed, food, biofuel, and losses) stages contributed to the CF by 2%, 11%, and 87%, respectively. Although Asia was the top grain producer, North America contributed 38% of the CF due to the greatest CF of the grave stage (2.5 Gt CO2eq.). The CF of grain crops will increase to 21.2 Gt CO2eq. in 2100, driven by the rise in N fertilization to meet the growing food demand without actions to stop the decline in N use efficiency. To meet the targets of climate change, we introduced an ambitious mitigation strategy, including the improvement of N agronomic efficiency (6% average target for the three crops) and manufacturing technology, reducing food losses, and global conversion to healthy diets, whereby the CF can be reduced to 5.6 Gt CO2eq. in 2100.

Utilizing plasma-generated N2O5 gas from atmospheric air as a novel gaseous nitrogen source for plants

Fixing atmospheric nitrogen for use as fertilizer is a crucial process in promoting plant growth and enhancing crop yields in agricultural production. Currently, the chemical production of nitrogen fertilizer from atmospheric N2 relies on the energy-intensive Haber–Bosch process. Therefore, developing a low-cost and easily applicable method for fixing nitrogen from the air would provide a beneficial alternative. In this study, we tested the utilization of dinitrogen pentoxide (N2O5) gas, generated from oxygen and nitrogen present in ambient air with the help of a portable plasma device, as a nitrogen source for the model plant Arabidopsis thaliana. Nitrogen-deficient plants supplied with medium treated with N2O5, were able to overcome nitrogen deficiency, similar to those provided with medium containing a conventional nitrogen source. However, prolonged direct exposure of plants to N2O5 gas adversely affected their growth. Short-time exposure of plants to N2O5 gas mitigated its toxicity and was able to support growth. Moreover, when the exposure of N2O5 and the contact with plants were physically separated, plants cultured under nitrogen deficiency were able to grow. This study shows that N2O5 gas generated from atmospheric nitrogen can be used as an effective nutrient for plants, indicating its potential to serve as an alternative nitrogen fertilization method for promoting plant growth.

Nitrogen fixation‐driven carbon sequestration: Brief communication

AbstractPrior to the commercial nitrogen fertilizer production in 1919, all the world's terrestrial and aquatic carbon was supported by nitrogen fixation. Annual N deposition to semi‐arid lands and temperate forests is less than 5 kg/ha‐year and 10 kg/ha, respectively. Plant and soil C/N ratios range from 9.9 to 29.8 and 9 to 14, respectively. In an equilibrium, sustainable ecosystem where N is not removed from soil pools and is only dependent on annual N inputs, maximum C sequestration rates are approximately 3.25 kg to 46 kg/ha for arid ecosystems and 23 to 101 kg/ha for forest ecosystems. Commercial N applications range from approximately 70 to 160 kg/ha‐year. Managed nitrogen fixation rates range from approximately 50 to 130 kg N/ha‐year. For each additional kg N‐entering forests, the additional C is approximately 13 kg. N‐fixing plants range from alder and lupines in the arctic, to Prosopis and Acacias in semi‐arid lands and the large trees Inga and Pentaclethra in tropical rainforests. If N‐fixing plants achieving 50 kg N/ha‐year were planted on the equivalent of a 447 km square, on six continents, the IEA target of 1.7Gt CO2 (0.72 Gt of carbon) capture capacity by 2030 https://www.ief.org/news/whats‐the‐target‐for‐carbon‐sequestration‐and‐how‐do‐we‐get‐there could be achieved.

Simultaneous Saccharification and Fermentation (SSF) of Blended Organic Fertilizer from Yam and Sweet Potato Peels

This study shows the production of organic fertilizer by utilization of yam and sweet potatoes peels through Simultaneous Saccharification and Fermentation (SSF) Method. Samples are categorized into sun-dried, sundried and autoclaved, Heat-dried, heat-dried and autoclaved, the fermentation process is carried out using alpha amylase and saccharomyces cerevisiae. Investigation of mineral elements (N, Cd, P, Zn, Pb, As, K, Hg.), in the eight varieties of Organic Fertilizer produced shows concentration of Cadmium (Cd) ranges from 0.0015 mg/kg to 0.0033 mg/kg), Nitrogen (N) in Percentage ranges from 2.3450% to 3.8550%; Phosphorus (P) ranges from 2.345 mg/kg to 3.607 mg/kg; Zinc (Zn) ranges from 2.215 mg/kg to 6.335 mg/kg. Lead (Pb) ranges from 0.00 mg/kg to 0.0015 mg/kg, potassium (K) ranges from 3.952 mg/kg to 6.213 mg/kg; Mercury and Arsenic nil. The study shows that Sweet Potato Peel (SDSPP) contains high Cadmium and potassium compare to other organic fertilizer produced. Sundried and Autoclaved Yam Peel (SDAYP) contains high percentage of Nitrogen (N), Heat Dried and Autoclaved Sweet Potato Peel (HDASPP) contains low Nitrogen, Sundried and Autoclaved Sweet Potato Peel (SDASPP) contains low phosphorus, Sundried Yam Peel (SDYP), Sundried and Autoclaved Yam Peels (SDAYP), Heat Dried Sweet Potato Peel HDSPP and Heat Dried Sweet Potato Peel (HDSPP) has zero trace of Lead (Pb) making it free of food intoxication from heavy metals, SDYP contains high phosphorus. These indicate that the samples will make quality organic fertilizer because it contains high Nitrogen, Phosphorus and potassium (NPK) which are essential elements required in plant structures.

Bipolar membrane electrodialysis for nutrient recovery from anaerobic digestion dewatering sidestream

Anaerobic digestion (AD) offers an efficient means for treating sludge generated in wastewater treatment plants (WWTPs), but nutrient-rich AD dewatering sidestream contributes as much as 30 % of the overall nutrient loading of WWTPs. Several electrochemical approaches are being developed as a sidestream treatment strategy to prevent return of nutrients to WWTP headworks and recover them for fertilizer production. One such method is to produce acids and bases, essential chemicals necessary to facilitate nutrient recovery, using bipolar membrane electrodialysis (BMED). In this study we show simultaneous separation of nutrients and production of acid/base streams with an additional consideration for increasing the concentration of ammonium and phosphate in the final product stream by systematically altering compartment flow rates and hence the retention time of each stream. Using a three-compartment BMED system with a synthetic sidestream containing 50 mM NH3-N and 2 mM PO4-P, we achieved up to 80 % ammonia removal (via a cation exchange membrane) and up to 60 % phosphate removal (via an anion exchange membrane) at a productivity of 34.2 L m−2 h−1. Separated ammonia was recovered (>90 %) in a subsequent membrane contactor (MC) that was fed with acid and base streams produced by the BMED unit. A phosphate recovery > 80 % was achieved by chemical precipitation (CP). In a combined BMED-MC-CP process, the concentrated final product contained 333.9 mM NH3-N and 3.1 mM PO4-P with an energy consumption of 8.9 kWh kg−1 N recovered. These results illustrate that the BMED-based treatment train is a promising strategy for nutrient recovery from AD dewatering sidestream.

Роль инвестиций в повышении экономической эффективности сельскохозяйственного производства

The research is aimed at studying the role of investments in increasing the economic efficiency of agricultural production. As a result of the analysis, a close relationship was revealed between the index of the physical volume of investments and the increase in gross output. More than 70 % of state support for agriculture is concentrated in the Central Federal District and the Volga Federal District. This fact determines the uneven development of rural areas. The authors note that the livestock industry, due to the high saturation of the domestic market, becomes less attractive to investors, as the risks of non-demand for products increase. A negative situation is also developing in grain production as a result of the lack of opportunities for the development of the production base, high export duties, reduced technological efficiency of cultivation, and high natural and climatic risks. A decrease in investments is also observed in the greenhouse industry, due to the highly competitive market and the lack of state support measures to reimburse capital costs for the construction of greenhouses. There is no stagnation in the industrial segment of dairy production. There is a tendency to suspend investment projects for the construction or modernization of livestock complexes, greenhouse complexes, grain terminals, as well as grain processing plants. The main attractive segments for investment at the moment are the production of fertilizers, grain cultivation, production of oils and fats, and production of dairy products.

Перспективы исследований фосфогипса как материала для строительства

Objective: analytical investigation of the potential use of hemihydrate (CaSO4 · 0.5H2O) and dihydrate (CaSO4 · 2H2O) calcium sulfate — phosphogypsum — a waste in the production of mineral fertilizers, as a construction material for the construction of roads, soil structures, material for the restoration of roads in the areas of repair of utility networks, as well as unloading of developed landfills for the storage of waste from processing phosphorus ores of chemical enterprises operating in the Russian Federation. Methods: analysis of the current situation at landfills of industrial enterprises, analysis of the knowledge of the issue of utilization and processing of phosphogypsum, as well as analytical (calculation) assessment of the possibility of replacing bulk materials (sand, crushed stone) with phosphogypsum common in construction. Results: this article discusses issues related to the assessment of the possibility of using phosphogypsum with a decrease in its local concentration in the zones of its application, as well as with the use of waste stored at landfills for many years. The considered options for prospective use of the material, which make it possible not only to preserve, but also to increase the operational characteristics of roads and other soil structures, while eliminating the potentially harmful effect of the material during operation associated with its dusting during storage. Practical significance: analysis of the current situation indicates that due to the active production in the Russian Federation, a huge amount of waste from such production — phosphogypsum — accumulates on the territory of industrial enterprises engaged in the processing of phosphorus ores and landfills assigned to these enterprises. The annual utilization of phosphogypsum at such enterprises is estimated at hundreds of thousands and millions of tons — huge dumps are formed, which pose a danger both from the point of view of groundwater pollution and from the point of view of man-made safety. With such large volumes of concentrated storage, the volumes of substances entering the soil and groundwater may repeatedly exceed the permissible values, but at the same time, with a lower concentration, the ingress of these substances into the soil may not only not harm the environment, but also have a positive effect in terms of increasing yield. The use of waste from such production facilities in road construction will solve the problems associated with the disposal of phosphogypsum.

Nutrient Recovery for Fertilizer Production and Wastewater Treatment for a Circular Economy

Nutrient Recovery for Fertilizer Production and Wastewater Treatment for a Circular Economy

Jalur Berkelanjutan dari Instalasi Pengolahan Air Limbah Bengkong Sadai di Batam

The urban center of Batam faces recurrent water crises. The introduction of the Bengkong Sadai Wastewater Treatment Plant (WWTP) offers a potential solution, converting domestic wastewater into reusable water, thereby addressing scarcity concerns. This research provides a comprehensive SWOT analysis of the WWTP, aiming to understand its potential for ensuring sustainable water management in Batam. We identified that while the WWTP capitalizes on state-of-the-art infrastructure, making a notable contribution to water reclamation and organic fertilizer production, it also confronts challenges like community engagement and operational complexities. Based on the analysis, the study emphasizes the criticality of proactive maintenance, robust stakeholder collaboration, and the need for a forward-thinking approach. This work sheds light on Batam's endeavors and offers a blueprint for other urban locales grappling with similar challenges.

Study the Physical Properties of Fertilizers and Plant Basin Parameters to Design the Tractor Operated Round Basin Maker cum Fertilizer Applicator for Orchard Crop

The physical form of fertilizer production is of extremely importance, both agronomically and in regard to satisfactory handling, transport, storage, and finally application to the field. The improvement of equipment for handling, storage, and application of granular fertilizer require a proper understanding of material properties and flow behavior. The most common problems encountered in fertilizers were caking, poor flow ability, segregation, dustiness and excessive hygroscopicity due to differences of physical properties. The physical properties such as moisture content, angle of repose and bulk density as important in designing the hopper and metering roller of fertilizer plays an important role in the storage, transport and application of fertilizer. The urea, Ammonium phosphate Sulphate, complex fertilizers and fertilizer ratio (10 26 26) per one orchard tree should be applied yearly trice based on crop requirement. The angle of repose value ranges 28° -37° the hopper angle was decided. For that, to flow the fertilizer freely from the hopper, the inclined angle of the hopper should be greater than 40° respectively. The lowest bulk density and tapped density observed 0.648 kg cm-3 and 0.708 kg cm-3 respectively. Coefficient friction for galvanized Iron (GI) material is very high So, based on the obtained results, a fertilizer applicator for orchard crops has been designed. The basin diameter of orchard palm varies from 1500 mm to 1750 mm the mean of 1650 mm. The root zone depth of orchard crop varies from 150 to 180 mm at radius of 1800 mm from the base of palm. The mean 171.66 mm hence depth of operation of machine was selected as 150 mm such that the machine does not interfere with root zone of orchard trees.

Practical strategies of phosphorus reclamation from sewage sludge after different thermal processing: Insights into phosphorus transformation

In the context of circular economy and global shortage of phosphorus (P) fertilizer production, it is crucial to effectively recover P during the treatment and disposal of sewage sludge (SS). Although thermal treatment of SS has been widely applied, a targeted P reclamation route is not yet well established. This study has comprehensively investigated and compared the physicochemical properties of SS and solid residues (hydrochar (HC), biochar (BC), sewage sludge ash (SSA), hydrochar ash (HCA), and biochar ash (BCA)) after application of three typical thermal treatment techniques (i.e., hydrothermal carbonization (180‒240 °C), pyrolysis (400‒600 °C) and combustion (850 ℃). P speciation and transformation during thermal processes were extensively explored followed by a rational proposal of effective P reclamation routes. Specifically, thermal processing decomposed organic P and converted non-apatite P to apatite P. Orthophosphate-P was found to be the main species in all samples. Physicochemical properties of the resulting thermal-derived products were significantly affected by the thermal techniques applied, thereby determining their feasibility for different P reclamation purposes. In particular, ash is not recommended for agricultural use due to higher harmful metals content, while acid leaching can be an alternative solution to synthesize non-Fe-containing P products because of the lower co-dissolved Fe content in the leachate. HC and BC offer the option for synthesis of Fe containing products. Eventually, HC and BC demonstrate great potential for agriculture application, however, a comprehensive risk assessment should be conducted before their real-world applications.

Urine-enriched biochar: Coupling sustainability in sanitation and agriculture

Linear models of fertilizer production and application are environmentally harmful. Predominant approaches to waste management treat human excreta as a pollutant rather than a source of nutrients for agriculture. Container-based sanitation (CBS) systems safely contain and transport excreta for treatment and reuse, though urine is often contained but not treated. A major challenge of urine-nutrient recovery is the shift in nitrogenous species in urine during storage, from urea to ammonia (NH3) and ammonium (NH4+), due to urease activity. This can lead to gaseous NH3 losses from urine that depletes its fertilizer potential. Urine-enriched biochar (UEBC) may act as a slow-release fertilizer of urine nutrients. We quantified the adsorption of nitrogen in fresh, stored, and CBS-style urine to wood waste, sewage sludge, and walnut shell biochars. These UEBCs were compared to urine-only treatments and fertilized and unfertilized controls in a greenhouse growth experiment. We found that the &amp;lt;500-µm biochar size fraction retained significantly more nitrogen than larger particles across biochars. Urine-nitrogen adsorption to biochar and uptake into plant tissue varied across biochar type and urine condition. The quantity of urine applied in urine-only treatments, regardless of type, was positively correlated with plant nitrogen uptake. Plant biomass did not differ significantly across treatments. These findings emphasize the need to optimize UEBC application for different urine and biochar conditions, particularly for CBS and other urine-diverting operations.