{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,22]],"date-time":"2025-12-22T08:15:51Z","timestamp":1766391351734,"version":"build-2065373602"},"reference-count":27,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2023,9,20]],"date-time":"2023-09-20T00:00:00Z","timestamp":1695168000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sustainability"],"abstract":"<jats:p>Phosphorus is a critical, irreplaceable raw material, and developing methods to recover P from secondary sources such as sewage sludge ash (SSA) is crucial. Two-compartment electrodialytic extraction (2C-ED) is one method where an electric DC field is applied to extract P and separate heavy metals simultaneously. Several process parameters influence 2C-ED, and they influence each other mutually. This paper explores chemometrics modeling to give insight into the 2C-ED process and, specifically, optimization of the experimental parameters towards 80% P extraction. A projections-to-latent-structures model was constructed based on new 2C-ED experiments conducted with one SSA type. The model was stable (high correlation factor and predictive power). Variable importance in the projection (VIP) plots showed that the influence of the variables was in the order: current &gt; duration &gt; L:S ratio &gt; stirring velocity &gt; dispersion solution (weak acid or distilled water). Contour plots were used for exploring different P extraction strategies. For example, more P mass per unit current was extracted at an L:S ratio of 7 compared to L:S 14. This shows that treating a thicker SSA suspension is preferable to optimize the current efficiency. The chemometric model proved valuable for optimizing the 2C-ED process and future scale-up.<\/jats:p>","DOI":"10.3390\/su151813953","type":"journal-article","created":{"date-parts":[[2023,9,20]],"date-time":"2023-09-20T21:26:32Z","timestamp":1695245192000},"page":"13953","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Extraction of Phosphorus from Sewage Sludge Ash\u2014Influence of Process Variables on the Electrodialytic Process"],"prefix":"10.3390","volume":"15","author":[{"given":"Lisbeth M.","family":"Ottosen","sequence":"first","affiliation":[{"name":"Department of Environment and Resource Engineering, DTU Sustain, Technical University of Denmark, 2800 Lyngby, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gunvor M.","family":"Kirkelund","sequence":"additional","affiliation":[{"name":"Department of Environment and Resource Engineering, DTU Sustain, Technical University of Denmark, 2800 Lyngby, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pernille E.","family":"Jensen","sequence":"additional","affiliation":[{"name":"Department of Environment and Resource Engineering, DTU Sustain, Technical University of Denmark, 2800 Lyngby, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kristine B.","family":"Pedersen","sequence":"additional","affiliation":[{"name":"Akvaplan-Niva AS, Fram Centre\u2014High North Research Centre for Climate and the Environment, Hjalmar Johansens Gate 14, 9007 Troms\u00f8, Norway"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,9,20]]},"reference":[{"key":"ref_1","unstructured":"European Commission (2020). Critical Raw Materials Resilience: Charting a Path towards Greater Security and Sustainability, European Commission."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1016\/j.chemosphere.2017.07.089","article-title":"Trends in the recovery of phosphorus in bioavailable forms from wastewater","volume":"186","author":"Melia","year":"2017","journal-title":"Chemosphere"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1136","DOI":"10.1016\/j.scitotenv.2015.08.059","article-title":"Sewage sludge ash\u2014A promising secondary phosphorus source for fertilizer production","volume":"542","author":"Herzel","year":"2016","journal-title":"Sci. Total. Environ."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1016\/j.envres.2017.01.002","article-title":"Fertilisers production from ashes after sewage sludge combustion\u2014A strategy towards sustainable development","volume":"154","author":"Gorazda","year":"2017","journal-title":"Environ. Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1809","DOI":"10.1016\/j.wasman.2007.08.011","article-title":"Phosphate fertilizer from sewage sludge ash (SSA)","volume":"28","author":"Franz","year":"2008","journal-title":"Waste Manag."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1634","DOI":"10.1016\/j.wasman.2010.04.009","article-title":"Production of technical grade phosphoric acid from incinerator sewage sludge ash (ISSA)","volume":"30","author":"Donatello","year":"2010","journal-title":"Waste Manag."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"963","DOI":"10.1016\/j.chemosphere.2013.01.101","article-title":"Extracting phosphorous from incinerated sewage sludge ash rich in iron or aluminum","volume":"91","author":"Ottosen","year":"2013","journal-title":"Chemosphere"},{"key":"ref_8","unstructured":"Ottosen, L.M., Jensen, P.E., Kirkelund, G.M., and Ebbers, B. (2015). Electrodialytic Separation of Heavy Metals from Particulate Material. (Patent no. WO 2015\/032903 Al)."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"191","DOI":"10.3389\/fenrg.2020.00191","article-title":"Review of Power-to-X Demonstration Projects in Europe","volume":"8","author":"Wulf","year":"2020","journal-title":"Front. Energy Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"113839","DOI":"10.1016\/j.apenergy.2019.113839","article-title":"Exploring hydrogen production for self-energy generation in electroremediation: A proof of concept","volume":"255","author":"Magro","year":"2019","journal-title":"Appl. Energy"},{"key":"ref_11","unstructured":"Government of Denmark (2023, February 06). Danmark Uden Affald (Denmark without Waste), Available online: http:\/\/mst.dk\/media\/130620\/danmark_uden_affald_ii_web-endelig.pdf."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1016\/j.wasman.2016.02.015","article-title":"Phosphorous recovery from sewage sludge ash suspended in water in a two-compartment electrodialytic cell","volume":"51","author":"Ottosen","year":"2016","journal-title":"Waste Manag."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"118684","DOI":"10.1016\/j.conbuildmat.2020.118684","article-title":"Sewage sludge ash as resource for phosphorous and material for clay brick manufacturing","volume":"249","author":"Ottosen","year":"2020","journal-title":"Constr. Build. Mater."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"404","DOI":"10.1016\/j.wasman.2018.01.007","article-title":"Change in re-use value of incinerated sewage sludge ash due to chemical extraction of phosphorus","volume":"74","author":"Li","year":"2018","journal-title":"Waste Manag."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2503","DOI":"10.1007\/s12649-018-0215-z","article-title":"Utilisation of Electrodialytically Treated Sewage Sludge Ash in Mortar","volume":"9","author":"Kappel","year":"2018","journal-title":"Waste Biomass Valorization"},{"key":"ref_16","unstructured":"Pedersen, K.B. (2015). Applying Multivariate Analysis to Developing Electrodialytic Remediation of Harbour Sediments from Arctic Locations. [Ph.D. Thesis, The Arctic University of Norway]."},{"key":"ref_17","unstructured":"U.S. EPA (2007). Method 3015A (SW-846): Microwave Assisted Acid Digestion of Aqueous Samples and Extracts, Revision 1."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1016\/j.electacta.2014.12.003","article-title":"Comparison of 2-compartment, 3-compartment and stack designs for electrodialytic removal of heavy metals from harbour sediments","volume":"181","author":"Pedersen","year":"2015","journal-title":"Electrochim. Acta"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"107138","DOI":"10.1016\/j.mineng.2021.107138","article-title":"Wastewater treatment plant processes affect P-phases in sewage sludge ashes","volume":"173","author":"Guhl","year":"2021","journal-title":"Miner. Eng."},{"key":"ref_20","first-page":"320","article-title":"Electrodialytic phosphorous recovery from suspended sewage sludge ash\u2013continuous or periodical stirring","volume":"2017","author":"Ottosen","year":"2017","journal-title":"Proc. Symp. EREM"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1016\/j.chemosphere.2014.12.013","article-title":"Comparison of two different electrodialytic cells for separation of phosphorus and heavy metals from sewage sludge ash","volume":"125","author":"Ebbers","year":"2015","journal-title":"Chemosphere"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1007\/s42768-020-00037-w","article-title":"Leaching behavior of phosphorous compounds from sewage sludge ash based on quantitative X-ray diffraction analysis","volume":"2","author":"He","year":"2020","journal-title":"Waste Dispos. Sustain. Energy"},{"key":"ref_23","unstructured":"Carlson, R., and Carlson, J.E. (2005). Design and Optimization in Organic Synthesis, Elsevier. [2nd ed.]."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1016\/j.electacta.2012.07.002","article-title":"Electrodialytic versus acid extraction of heavy metals from soil washing residue","volume":"86","author":"Jensen","year":"2012","journal-title":"Electrochim. Acta"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"100092","DOI":"10.1016\/j.cscee.2021.100092","article-title":"Electric resistivity during electrodialytic recovery of phosphorous from sewage sludge ash","volume":"3","author":"Ottosen","year":"2021","journal-title":"Case Stud. Chem. Environ. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/j.wasman.2016.03.040","article-title":"Valorisation of ferric sewage sludge ashes: Potential as a phosphorus source","volume":"52","author":"Guedes","year":"2016","journal-title":"Waste Manag."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1251","DOI":"10.2166\/wst.2016.620","article-title":"Comparison of phosphorus recovery from incineration and gasification sewage sludge ash","volume":"75","author":"Viader","year":"2017","journal-title":"Water Sci. Technol."}],"container-title":["Sustainability"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2071-1050\/15\/18\/13953\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:53:45Z","timestamp":1760129625000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2071-1050\/15\/18\/13953"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,9,20]]},"references-count":27,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2023,9]]}},"alternative-id":["su151813953"],"URL":"https:\/\/doi.org\/10.3390\/su151813953","relation":{},"ISSN":["2071-1050"],"issn-type":[{"type":"electronic","value":"2071-1050"}],"subject":[],"published":{"date-parts":[[2023,9,20]]}}}