This work evaluates the release of phosphorus contained in the digestate from the anaerobic digestion of pig manure, through an acidification process. The objective of this acidification is to increase the amount of phosphorus available in the digestate liquid fraction and, subsequently, recover this element by chemical precipitation in the form of struvite or calcium phosphate. Two digestate samples (one fresh and one old) were studied and treated by adding various amounts of sulphuric acid to the different digestate fractions (raw digestate, solid fraction and liquid fraction). For the raw digestate, phosphorus releases higher than 95% were obtained for pH 4.0. In the last part of the experiment, the influence of acid pre-treatment on the reaction yield of phosphorus precipitation, in the form of struvite or calcium phosphate, was determined. Improvements in reaction yield were obtained up to 15% for struvite and 80% for calcium phosphate, increasing also in 7.5 times the amount of phosphorus available in the digestate liquid fraction, for both cases.
", "keywords": ["Biofertiliser", "FEASIBILITY", "NUTRIENT RECOVERY", "PH", "Struvite", "Swine", "SWINE WASTE-WATER", "0211 other engineering and technologies", "02 engineering and technology", "7. Clean energy", "01 natural sciences", "CALCIUM", "Acidification", "ANAEROBIC-DIGESTION", "Environmental Chemistry", "PHOSPHORUS REMOVAL", "Animals", "Chemical Precipitation", "Toxicology and Mutagenesis", "Anaerobiosis", "Organic waste", "SLUDGE", "0105 earth and related environmental sciences", "Phosphorus", "General Medicine", "Pollution", "6. Clean water", "Manure", "Nutrient recovery", "Health", "Earth and Environmental Sciences", "Release", "PRECIPITATION", "Waste and Biomass Management & Valorization", "CRYSTALLIZATION"]}, "links": [{"href": "https://link.springer.com/content/pdf/10.1007/s11356-020-10918-6.pdf"}, {"href": "https://doi.org/10.1007/s11356-020-10918-6"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Science%20and%20Pollution%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s11356-020-10918-6", "name": "item", "description": "10.1007/s11356-020-10918-6", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s11356-020-10918-6"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-10-03T00:00:00Z"}}, {"id": "10.1016/j.scitotenv.2020.143726", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:16:01Z", "type": "Journal Article", "created": "2020-11-24", "title": "A systematic comparison of commercially produced struvite: Quantities, qualities and soil-maize phosphorus availability", "description": "Production of struvite (MgNH4PO4\u00b76H2O) from waste streams is increasingly implemented to recover phosphorus (P), which is listed as a critical raw material in the European Union (EU). To facilitate EU-wide trade of P-containing secondary raw materials such as struvite, the EU issued a revised fertilizer regulation in 2019. A comprehensive overview of the supply of struvite and its quality is presently missing. This study aimed: i) to determine the current EU struvite production volumes, ii) to evaluate all legislated physicochemical characteristics and pathogen content of European struvite against newly set regulatory limits, and iii) to compare not-regulated struvite characteristics. It is estimated that in 2020, between 990 and 1250 ton P are recovered as struvite in the EU. Struvite from 24 European production plants, accounting for 30% of the 80 struvite installations worldwide was sampled. Three samples failed the physicochemical legal limits; one had a P content of <7% and three exceeded the organic carbon content of 3% dry weight (DW). Mineralogical analysis revealed that six samples had a struvite content of 80-90% DW, and 13 samples a content of >90% DW. All samples showed a heavy metal content below the legal limits. Microbiological analyses indicated that struvite may exceed certain legal limits. Differences in morphology and particle size distribution were observed for struvite sourced from digestate (rod shaped; transparent; 82 mass%\u202f<\u202f1\u202fmm), dewatering liquor (spherical; opaque; 65 mass% 1-2\u202fmm) and effluent from upflow anaerobic sludge blanket reactor processing potato wastewater (spherical; opaque; 51 mass%\u202f<\u202f1\u202fmm and 34 mass%\u202f>\u202f2\u202fmm). A uniform soil-plant P-availability pattern of 3.5-6.5\u202fmg P/L soil/d over a 28\u202fdays sampling period was observed. No differences for plant biomass yield were observed. In conclusion, the results highlight the suitability of most struvite to enter the EU fertilizer market.", "keywords": ["2. Zero hunger", "Struvite", "0211 other engineering and technologies", "Magnesium Compounds", "Phosphorus", "02 engineering and technology", "Zea mays", "01 natural sciences", "6. Clean water", "Phosphates", "12. Responsible consumption", "Chemistry", "Soil", "Bio-based fertilizers; Circular economy; Magnesium ammonium phosphate; Nutrient recovery; Phosphorus recovery; Struvite characterization; Magnesium Compounds; Phosphates; Soil; Struvite; Phosphorus; Zea mays", "Biology", "Engineering sciences. Technology", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://arpi.unipi.it/bitstream/11568/1138036/1/STOTEN_struvite.pdf"}, {"href": "https://doi.org/10.1016/j.scitotenv.2020.143726"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Science%20of%20The%20Total%20Environment", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.scitotenv.2020.143726", "name": "item", "description": "10.1016/j.scitotenv.2020.143726", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.scitotenv.2020.143726"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2021-02-01T00:00:00Z"}}, {"id": "10.1016/j.jtice.2020.11.031", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:15:53Z", "type": "Journal Article", "created": "2020-12-03", "title": "Struvite production from dairy processing wastewater: Optimizing reaction conditions and effects of foreign ions through multi-response experimental models", "description": "Abstract Struvite is the preferred form of phosphorus recovery for fertilizer by chemical precipitation. The concentration of phosphorus in raw wastewater from dairy processing is higher than acceptable values for prevention of water pollution. Along with phosphorus, potassium and calcium are its main counterions with high concentration. Thus, calcium phosphate salts are prompt to precipitate and decrease struvite production. The effect of such phosphate counter-ions were optimized using design of experiments and desirability function to maximize both phosphorus recovery and struvite production. Under optimum conditions, the yields were 98.6\u00a0\u00b1\u00a01.1 and 85.7\u00a0\u00b1\u00a02.5 percent for phosphorus recovery and struvite precipitation, respectively. Factors optimization was achieved with desirability D\u00a0=\u00a00.995. By in-vitro assay of nutrients release, the product demonstrated better phosphorus availability than the one obtained with high calcium dose in reactor. The obtained molar ratios of dose can serve in wastewater treatment coupled to phosphorus precipitation with a fertilizer value product.", "keywords": ["Nutrients release kinetics", "Counterions effect", "Phosphorus recovery", "Struvite precipitation", "Multi-response", "Desirability", "01 natural sciences", "6. Clean water", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.jtice.2020.11.031"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20the%20Taiwan%20Institute%20of%20Chemical%20Engineers", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.jtice.2020.11.031", "name": "item", "description": "10.1016/j.jtice.2020.11.031", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.jtice.2020.11.031"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-12-01T00:00:00Z"}}, {"id": "10.2139/ssrn.4633350", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:18:43Z", "type": "Journal Article", "created": "2023-11-14", "title": "Nutrient Recovery from Digestate: Pilot Test Experiments", "description": "A series of technologies have been employed in pilot-scale to process digestate, i.e. the byproduct remaining after the anaerobic digestion of agricultural and other wastes, with the aim of recovering nutrients and reducing the load of solids and organics from it, hence improving the quality of digestate for potential subsequent reuse. In this case the digestate originated from a mixture of dairy and animal wastes and a small amount of agricultural wastes. It was processed by the application of several treatments, applied in series, i.e. microfiltration, ultrafiltration, reverse osmosis, selective electrodialysis and combined UV/ozonation. The initially applied membrane filtration methods (micro- and ultra-filtration) removed most of the suspended solids and macromolecules with a combined efficiency of more than 80%, while the reverse osmosis (at the end) removed almost all the remaining solutes (85-100%), producing sufficiently clarified water, appropriate for potential reuse. In the selective electrodialysis unit over 95% of ammonium and potassium were recovered from the feed, along with 55% of the phosphates. Of the latter, 75% was retrieved in the form of struvite.", "keywords": ["Struvite", "Ammonium Compounds", "Animals", "Anaerobiosis", "Nutrients", "Phosphates"]}, "links": [{"href": "https://doi.org/10.2139/ssrn.4633350"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Environmental%20Management", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.2139/ssrn.4633350", "name": "item", "description": "10.2139/ssrn.4633350", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.2139/ssrn.4633350"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-01-01T00:00:00Z"}}, {"id": "10.3390/agronomy12010182", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:19:01Z", "type": "Journal Article", "created": "2022-01-12", "title": "Evaluating the Fertilising Potential of Blended Recovered Nutrients in Horticultural Growing Medium on Viola x wittrockiana L.", "description": "Viola x wittrockiana L. is an ornamental plant in high demand in horticulture. It is becoming more critical for greenhouse growers to focus on sustainable production to enhance plant quality while reducing negative environmental impacts. Therefore, assessing the effect of recycled phosphorous (P) and nitrogen (N) sources on the growth of viola could become very useful for producers in terms of sustainability. This experiment analysed the optimal fertiliser composition to grow viola using recovered fertilisers in a greenhouse trial under controlled conditions. Well-rooted viola plugs were grown in a standard peat-based growing medium. Using recycled sources of P and N as struvite and potassium struvite, ammonium sulphate, and ammonium nitrate, 14 fertiliser blends were prepared, tested, and compared with the slow-release commercial fertiliser Osmocote. Plants treated with ammonium nitrate showed healthy growth and optimal plant N concentrations. In contrast, most blends using the recovered ammonium sulphate resulted in an unacceptable increase of ammonium concentrations in the growing medium. The combination of ammonium sulphate and potassium sulphate caused an increase in the electrical conductivity in the growing medium, negatively affecting plant growth. However, blend 13 containing struvite, ammonium sulphate and potassium struvite expressed the best chemical composition with non-significant differences in the biomass from the positive controls, as it reduced the amount of potassium sulphate needed. Our results indicate that fertiliser blends containing P as struvite, N as ammonium nitrate or reduced amount of ammonium sulphate, and K as potassium struvite can substitute the use of mineral fertiliser blends to grow ornamental plant species as viola.
", "keywords": ["Agriculture and Food Sciences", "nutrient recycling", "0301 basic medicine", "alternative fertilisers", "WASTE", "plant nutrition", "struvite", "PANSY", "12. Responsible consumption", "03 medical and health sciences", "PLANTS", "recovered nutrients; ornamental plants; greenhouse flowers; sustainable plant production; alternative fertilisers; plant nutrition; struvite; nutrient recycling", "ornamental plants", "recovered nutrients", "greenhouse flowers", "2. Zero hunger", "S", "Agriculture", "04 agricultural and veterinary sciences", "15. Life on land", "DIGESTATE", "sustainable plant production", "MINERAL FERTILIZERS", "GROWTH", "0401 agriculture", " forestry", " and fisheries", "info:eu-repo/classification/ddc/640", "Agronomy and Crop Science", "FORM"]}, "links": [{"href": "http://www.mdpi.com/2073-4395/12/1/182/pdf"}, {"href": "https://www.mdpi.com/2073-4395/12/1/182/pdf"}, {"href": "https://doi.org/10.3390/agronomy12010182"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Agronomy", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.3390/agronomy12010182", "name": "item", "description": "10.3390/agronomy12010182", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.3390/agronomy12010182"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-01-12T00:00:00Z"}}, {"id": "38280247", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:23:01Z", "type": "Journal Article", "created": "2023-11-14", "title": "Nutrient Recovery from Digestate: Pilot Test Experiments", "description": "A series of technologies have been employed in pilot-scale to process digestate, i.e. the byproduct remaining after the anaerobic digestion of agricultural and other wastes, with the aim of recovering nutrients and reducing the load of solids and organics from it, hence improving the quality of digestate for potential subsequent reuse. In this case the digestate originated from a mixture of dairy and animal wastes and a small amount of agricultural wastes. It was processed by the application of several treatments, applied in series, i.e. microfiltration, ultrafiltration, reverse osmosis, selective electrodialysis and combined UV/ozonation. The initially applied membrane filtration methods (micro- and ultra-filtration) removed most of the suspended solids and macromolecules with a combined efficiency of more than 80%, while the reverse osmosis (at the end) removed almost all the remaining solutes (85-100%), producing sufficiently clarified water, appropriate for potential reuse. In the selective electrodialysis unit over 95% of ammonium and potassium were recovered from the feed, along with 55% of the phosphates. Of the latter, 75% was retrieved in the form of struvite.", "keywords": ["Struvite", "Ammonium Compounds", "Animals", "Anaerobiosis", "Nutrients", "Phosphates"]}, "links": [{"href": "https://doi.org/38280247"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Environmental%20Management", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "38280247", "name": "item", "description": "38280247", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/38280247"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-01-01T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Struvite&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Struvite&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Struvite&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Struvite&offset=6", "hreflang": "en-US"}], "numberMatched": 6, "numberReturned": 6, "distributedFeatures": [], "timeStamp": "2026-09-20T21:03:43.872581Z"}