![\"\"](\"https:\/\/renewable-carbon.eu\/news\/media\/2026\/03\/Z1_fad871-1024x576.jpeg\")
MSWI ash consists of up to 95 percent bottom ash, and fly ash, which is produced from burning municipal solid waste. It is considered hazardous waste due to high concentrations of heavy metals, toxic dioxins, furans and soluble salts.<\/p>\n\n\n\n
To tackle this issue, scientists from the Cologne University of Applied Sciences (TH K\u00f6ln) and RWTH Aachen University, have started exploring whether this harmful residue ash could be repurposed into a climate-friendly raw material.<\/p>\n\n\n\n
Led by the Bergischer Waste Management Association (BAV), the project focuses on a natural reaction known as carbonation, in which the minerals inside MSWI ash chemically react with carbon dioxide (CO2).<\/p>\n\n\n\n
An eco-friendly solution<\/h3>\n\n\n\n
Germany produces around six million tons of bottom ash from municipal waste incineration each year. This byproduct is already processed in specialized facilities to recover materials and remove contaminants.<\/p>\n\n\n\n
It is ultimately converted into a cleaned finished ash through targeted screening and sorting steps. \u201cThe mineral components it contains are capable of absorbing and permanently binding CO2, a process known as carbonation,\u201d Bj\u00f6rn Siebert, PhD, a civil engineering professor at TH K\u00f6ln, stated.<\/p>\n\n\n\n
Siebert elaborated that the project\u2019s goal is to develop a practical carbonation process in order to assess whether the resulting material can be used in road construction or concrete production.<\/p>\n\n\n
![\"The](\"https:\/\/renewable-carbon.eu\/news\/media\/2026\/03\/Z2_1e8b02-1024x576.webp\")
To test the idea outside if the lab, BAV is building a new\u00a0technical pilot plant\u00a0at the Leppe Waste Management Center near Lindlar, Germany. The plant\u00a0will\u00a0trial multiple carbonation methods on ash supplied by industry\u00a0partner refer GmbH.<\/p>\n\n\n\n
Axel Wellendorf, PhD, a mechanical engineering professor at TH K\u00f6ln, said they plan to pursue at least two different approaches, each with its own advantages and drawbacks.<\/p>\n\n\n\n
\u201cWet carbonation under water allows greater CO2 uptake but requires energy for subsequent drying,\u201d Wellendorf highlighted. \u201cIn contrast, moist carbonation with limited moisture forms a relatively dense carbonated layer on the ash surface, which stores less CO2 because it cannot penetrate into the interior.\u201d<\/p>\n\n\n\n
Construction and concrete production<\/h3>\n\n\n\n
The team will first test the carbonation processes, and then build a flexible pilot plant which allows them to adjust the methods under real conditions. It will then focus on how to utilize the resulting material.<\/p>\n\n\n\n
\u201cOur goal is to substitute raw materials that are otherwise extracted with high energy input,\u201d Siebert pointed out. \u201cIn unbound form, our carbonated ash could replace gravel or sand in road construction or earthworks.\u201d<\/p>\n\n\n
![\"Municipal](\"https:\/\/renewable-carbon.eu\/news\/media\/2026\/03\/Z3_d6f09f-1024x576.webp\")
At the same time, the researchers are also studying whether the ash could work as a\u00a0concrete binder.\u00a0This application requires strict quality control, which is\u00a0why the\u00a0project includes tests on selective crushing and further material\u00a0processing to ensure consistent particle size and composition.<\/p>\n\n\n\n
\u201cIf we succeed in providing carbonated ash that meets the relevant standards and environmental requirements, this would be an important step for the circular economy and climate protection,\u201d Wellendorf concluded in a press release.<\/p>\n","protected":false},"excerpt":{"rendered":"
German researchers have been developing a new technique to permanently bind carbon dioxide within municipal solid waste incineration (MSWI) ash, and turn it into a usable substitute for sand, gravel, or even concrete components. MSWI ash consists of up to 95 percent bottom ash, and fly ash, which is produced from burning municipal solid waste. It is considered hazardous waste due to […]<\/p>\n","protected":false},"author":59,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","nova_meta_subtitle":"The researchers team from TH Cologne and RWTH Aachen University are comparing wet and moist carbonation to see which stores the most CO2","footnotes":""},"categories":[5572,17143],"tags":[13554,17617,12430,27608,21452,10416,13553,11749,27607,15993],"supplier":[27602,27603,27606,98,11186],"class_list":["post-174133","post","type-post","status-publish","format-standard","hentry","category-bio-based","category-recycling","tag-beton","tag-bioasphalt","tag-buildingmaterial","tag-carbonation","tag-carbonstorage","tag-circulareconomy","tag-concrete","tag-construction","tag-flyash","tag-wastemanagement","supplier-bergischer-abfallverband-bav","supplier-entsorgungszentrum-leppe","supplier-refer-gmbh","supplier-rheinisch-westfaelische-technische-hochschule-aachen-rwth","supplier-technische-hochschule-koeln"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/174133","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=174133"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/174133\/revisions"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=174133"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=174133"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=174133"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=174133"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}