Tech
From sewer to furnace: How wastewater sludge is greening steel production
By turning wastewater sludge into biocoal and green hydrogen, EU researchers are helping reduce the steel industry’s environmental impact.
What comes out of our wastewater treatment plants may not be very appealing, but the real problem is what is left behind after water treatment. Wastewater plants produce a liquid sludge that is usually dried and then burned or dumped. This is costly, polluting, and has long been considered wasteful.
A group of researchers see it differently. This sludge, they argue, could become an unlikely ally in the fight against climate change—a feedstock for producing the hydrogen and carbon needed to make greener steel.
“This sludge has value, it is not just waste,” said David Chiaramonti, professor of energy systems, energy economics and bioeconomy at the Polytechnic University of Turin in Italy. “With it we can create things like carbon and hydrogen.”
Towards green steel
Chiaramonti is leading an EU research initiative called H2STEEL that brings together academics and steel industry experts from France, Italy, the Netherlands, Spain and the UK. Their goal is to design a process to extract the useful materials from wastewater sludge so that they can be reused and help reduce the steel industry’s emissions.
Steel production is essential for everything from airplanes and cars to buildings and wind turbines. It is also a major driver of climate change.
According to a 2023 report by the International Energy Agency, the steel sector alone accounts for 8% of global CO2 emissions. By comparison, the aviation industry emits about 2.5% of global CO2 emissions.
Cutting these emissions is particularly difficult. Steelmaking is complex and typically requires carbon-rich ingredients, which inevitably release greenhouse gases. That makes it one of the hardest industries to decarbonize—and one of the most expensive to transform.
Traditional steel production methods face increasing carbon pricing pressures across Europe under the EU’s Emissions Trading System. According to market forecasts, carbon prices could reach €120–150 per metric ton of CO2 by 2030, potentially adding significant costs per ton of steel produced.
For a global steel market worth more than €2.5 trillion annually, finding affordable low-carbon alternatives is urgent.
Hot sludge
This is where H2STEEL comes in. “It’s a good example of the circular economy,” said Chiaramonti. “We take a little-used resource, wastewater sludge, and make it useful again.”
The process works in two main steps. First, sludge is heated without oxygen to create biocoal, in a process called “carbonization.” Then methane from biogas plants is processed using this biocoal as a catalyst to produce hydrogen.
During this process, the biocoal becomes even richer in carbon, making it valuable for steelmaking. Another by-product, phosphorus, is separated for use in fertilizers.
Both outputs—hydrogen and carbon-rich biocoal—could help make steel cleaner. Traditional steelmaking burns coal with iron ore, releasing CO2. With H2STEEL’s approach, hydrogen can replace some of that coal. Meanwhile, the biocoal substitutes regular coal, turning waste into a useful industrial input.
The team is now building a 4-meter-tall processing machine in Turin to demonstrate the technology. “We break the biomethane into carbon and hydrogen by using the carbonized sludge at 900°C,” explained Chiaramonti. “That’s how we turn it into biocoal and circular hydrogen.”
Carbon and hydrogen
Official results are not available yet for the project, which will finish in March 2026, but the potential is significant.
Decarbonizing steel is attracting intense research efforts, from electrical furnaces to hydrogen-based processes. H2STEEL’s sludge-based approach could slot into this wider transformation.
“This technology is very flexible,” said Jan Wiencke, team leader for sustainable carbon at steelmaker ArcelorMittal’s research center in Maizières, northern France.
Headquartered in Luxembourg, ArcelorMittal is the second-largest steel producer in the world.
The company is also a partner in the H2STEEL project and hopes to be able to use the technology being developed at their steel plants.
“Whether we use a hydrogen furnace or an electrical one, we will still need ingredients like carbon and hydrogen in our processes,” said Wiencke.
“With this technology we can already reduce emissions now, and it will continue to be useful in the future.”
Other partners include Leiden University in the Netherlands and Imperial College London.
Next steps
One of H2STEEL’s biggest advantages is speed. If trials succeed, the technology could be rolled out within a few years—unusually fast in an industry where infrastructure changes often take decades.
Still, challenges remain. “We need to secure the sludge, transform it, and deliver it to the steel plants,” said Chiaramonti. Setting up supply chains and minimizing costs will be crucial.
ArcelorMittal, which aims to be carbon neutral by 2050, is watching closely. “This is a great technology for the steel industry, but it must prove itself economically,” said Wiencke.
A patent is already pending, and the partners are eager to see results from the demonstrator. “What we’re doing looks very promising,” said Chiaramonti. “Now it’s a question of taking the last steps.”
If successful, H2STEEL could deliver more than a technical breakthrough. By turning waste into valuable raw materials, it embodies the principles of the circular economy, helping Europe stay competitive while moving closer to its net-zero goals.
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Tech
The Latest Repair Battlefield Is the Iowa Farmlands—Again
Iowa lawmakers voted to advance state House bill 751 last week, legislation that would ensure farmers in the state can freely repair their own agricultural equipment, like tractors. This Tuesday, the bill was renamed to House File 2709, and it will be voted on again. Should the political winds align, it will go through the Iowa House and Senate before the Iowa Legislature adjourns on April 21.
The bill is the first of nearly 57 state bills supported by repair advocates across the country in 2026. Many of them focus on farm equipment in states like Oklahoma, Wyoming, Delaware, and West Virginia. Repair advocates hope a win in Iowa—the second-highest-grossing state in the US for agricultural products, behind California—will help further legislative and broader efforts to make phones, cars, and other devices more repairable.
“This isn’t just a blue state thing; this isn’t just a Colorado activist thing,” says Elizabeth Chamberlain, director of sustainability for the right-to-repair advocate arm of iFixit. “Its real. Farmers have trouble repairing their equipment and want change.”
Farmers and their tractors have long been a focal point of the right-to-repair movement, the ever-growing global effort to let product owners fix their own devices and equipment without manufacturer approval. Farmers who use tractors to plant, cultivate, and harvest crops often need to repair their equipment while they work. Waiting for manufacturer approval to get something fixed, or taking the time to bring the equipment to an approved dealership, can cause delays, frustration, and missed opportunities to harvest crops.
The Iowa bill defines which agricultural equipment it covers, including tractors, trailers, combines, sprayers, balers, and other equipment used to cultivate and harvest crops. It excludes aircraft and irrigation equipment, along with jet skis and snowmobiles.
Manufacturers would also be required to provide owners with data—documentation, like manuals, and access to embedded operating software—on their tractors, including future patches and fixes, all without charging for it or requiring authorization for internet access. The bill also limits the use of digital locks—software restrictions that prevent accessing features without manufacturer approval.
Oh Deere
The most prominent opposition to the Iowa bill is tractor manufacturer John Deere, which has a long history of opposing repair efforts and frustrating farmers who want to take more control of their equipment. The company is still fighting a lawsuit the US Federal Trade Commission levied against John Deere in January 2025 for “unlawful” repairability policies. The company has lobbied against the Iowa bill and outright opposes its passing.
“John Deere is steadfast in supporting farmers’ ability to repair their equipment,” wrote a John Deere representative in a statement responding to WIRED’s inquiry. “And we back that up by offering industry-leading self-repair tools and resources to both equipment owners and alternative service providers.”
John Deere points to its online repair hub that catalogs ways its product owners can repair their products. Chamberlain says it is true that John Deere offers self-repair options, but they are not always in line with the reality of what farmers need to make fixes in the moment.
“Ultimately, it doesn’t matter if the vast majority of repairs are possible if there’s a repair that takes your equipment down and that means loss of harvest or having to wait weeks for a dealer representative to come out,” Chamberlain says.
John Deere has said it supports third-party and self-repair of its equipment before. In 2023, John Deere and the American Farm Bureau agreed to a memorandum of understanding about how the company would allow access to repairs on its products in response to repair laws passing in states like Colorado. But repair advocates criticized the move, saying the memorandum did little to make John Deere adhere to new regulations.
Tech
We Gave These Android-Ready Earbuds a 9/10, and They’re Just $180
If you’re an esteemed Android user like me, and you felt left out of yesterday’s deal on the AirPods Pro 3, I’ve got you covered today with an even bigger discount on the Pixel Buds Pro 2. Both Amazon and Best Buy have the hazel color marked down from $229 to $180, a $49 discount on Google’s most upgraded wireless earbuds.
The first change you’ll notice from the previous generation Pixel Buds Pro is that the newer model is much lighter, and the buds are 27 percent smaller. As a result, these are an excellent choice for anyone with small ears, and they stay put super well. Reviewer Parker Hall “had no problem doing hours of tree pruning and going on long sweaty runs in Portland’s early fall heat wave.”
With some help from top-notch physical sound isolation, the active noise-canceling on these is just as good as Apple’s and even goes toe-to-toe with big hitters like Bose and Sony. The transparency mode works just as well, too, with a wider range and clearer audio than a lot of other headphones offer. When it’s time to actually turn up the tunes, you can enjoy a wide, natural soundstage that has excellent detail in the midrange and clear, sparkling treble.
The Gemini integration, unfortunately, leaves a bit to be desired. It’s not the smoothest experience, particularly when asking multiple questions, and the Pixel Buds Pro 2 aren’t offering anything that other earbuds can’t do. Apple’s live translations and heart rate monitors are more useful features, but if you’re on Android, you’re locked out of them anyway.
If you’re interested in upgrading your earbud game, and you already have a Pixel, you can grab the Pixel Buds Pro 2 in hazel for $180 from either Amazon or Best Buy. If that color doesn’t suit you, I also spotted lesser discounts on the peony color for $189, or the porcelain color for $210. For anyone who isn’t already sold on the Pixel Buds Pro 2, make sure to swing by our guide to the best wireless earbuds, with picks for both Apple and Android owners.
Tech
‘Uncanny Valley’: Pentagon vs. ‘Woke’ Anthropic, Agentic vs. Mimetic, and Trump vs. State of the Union
Guys, before we go to break, there’s something very near and dear to my heart that WIRED wrote about this week. It’s something I love even more than biathlon. It is undersea internet cables.
Leah Feiger: I love when you talk about this. I think that the first time you brought this up to me was approximately one week into your tenure as executive editor, and you’re like, “Leah, do you know what I love?” and it’s undersea internet cables.
Brian Barrett: Yeah. I was like, “Number one, undersea internet cables. Number two, my children. Number three …” that was sort of the gist of it. That’s how I always introduce myself. I want to take everybody back to December 14th, 1988. The top movie in theaters is Twins starring Arnold Schwarzenegger and Danny DeVito.
Zoë Schiffer: Legitimately never heard of it.
Leah Feiger: Wait, Zoë. What?
Brian Barrett: What? Anyway, Arnold is agentic and Danny DeVito’s mimetic. The top song—
Zoë Schiffer: Now I get it.
Brian Barrett: —the top song is “Look Away” by Chicago. Now that, I also am not—I don’t remember that one at all. And the first undersea fiber optic cable connecting the United States, UK and France went live. This was the day that the internet went global, which is crazy—
Zoë Schiffer: That is crazy.
Brian Barrett: —that it was relatively recent. The reason we’re writing about it now is that that original cable, which is called TAT-8, is being pulled up. It’s out of commission. It’s old, it’s decrepit, so I identify, and it’s being pulled up and put out to pasture because the technology’s gotten better. But in this great feature that we published, it is a look at how this changed the world basically, and how we take for granted—but the reason I am so into undersea cable stories is because it’s so easy to forget that the internet is a physical thing and that the maintenance of those things is really what makes all this connectivity happen. So yeah, TAT-8. Any other fond memories of TAT-8? Or, no. What did you guys think reading this feature?
Zoë Schiffer: Well, famously we were not alive in 1988.
Leah Feiger: Yeah. Sorry, Brian. You’re older than us. Just a reminder.
Brian Barrett: Hurts.
Zoë Schiffer: But the part of this story that I wanted to talk about, which felt like a real intersection of both of your interests was the myth of the shark attacks.
Brian Barrett: Oh, yeah.
Leah Feiger: OK. So to back up a little bit, these cables, at the very beginning, when they were put in, Brian would be able to talk about this way more because he’s kind of a freak about cables if you haven’t realized already. These cables would sometimes have unexplained damage, and looking back on it years later, engineers figured out that this kind of happens, that if you are putting cables underseas, there will be wind, there will be changes, things will get moved around. Of course, there will be damages, but that is not how they felt at the time. These engineers assumed that it was sharks, that sharks were biting their cables, that they were destroying the internet. The cables were reinforced with all these protective layers, all of these things, because they were like, “Oh, my God, the sharks are quite literally ending all of this for us.” But this article goes into great detail of how they figured out it wasn’t the sharks, and by thinking that it was the sharks, it actually helped make all of this technology that much better and stronger, but the sharks were innocent, you guys. The sharks were innocent.
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