Seaweed-based ingredient can help turn dirt into 3D-printed walls

University of Colorado at Boulder

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Earthen Rituals, exhibited at the 2026 Venice Architecture Biennial, is constructed with 3D-printed earthen materials.

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Credit: Alessandro Terranova

An ingredient that gives ice cream a creamier texture could make natural earthen materials like clay and sand easier to 3D-print into durable structures, according to new research led by scientists at the University of Colorado Boulder.

The discovery could help turn construction waste into building materials with lower environmental impact. 

“From termite mounds to adobe buildings, humans and animals have been building with earth since the dawn of time,” said Wil Srubar, professor in the Department of Civil, Environmental and Architectural Engineering. “But there hasn’t been a lot of science to how earthen builders design the materials. So, we wanted to use scientific knowledge and tools to understand it.”

In nature, termites construct towering mounds. Wasps build intricate nests, and honeycomb worms create reef-like structures along coastlines. Rather than relying on cement, these organisms use biopolymers, which are large biological molecules that act like glue, often found in saliva, to bind natural materials like soil and clay together. 

Inspired by nature’s designs, Srubar and his team, including researchers at Columbia University in New York, set out to investigate which biopolymer could bind earthen materials and make them 3D-printable. 

The team tested five biopolymers, including legume-derived guar gum, locust bean gum and cassia gum. These compounds are commonly found in food products like salad dressings to keep oil and water from separating. They also studied sodium alginate, derived from seaweed, and xanthan gum, produced by fermenting sugar. 

The researchers found that locust bean gum could hold earthen materials tightly together by binding soil particles into a stronger network. But that same effect made the material harder to push through a 3D-printer nozzle. 

Sodium alginate, often found in ice cream and used to make spherical foods like popping boba, produced the opposite effect. Instead of functioning like a glue, the polymer changed the electrical charges on clay particles, causing them to repel one another, similar to how the same poles of two magnets push each other away. 

As a result, adding sodium alginate to clay and sand produced materials that allowed the particles to suspend in a stable mixture while still flowing smoothly through a 3D printer.

Then the team searched for the best formulation. To natural earth excavated from a granite quarry near Golden, Colorado, they added just 0.12% of sodium alginate, which produced a material that was both strong and printable.  It could withstand 25% more pressure than earth without the biopolymer and could be printed 33% faster. 

Using the formula, the team printed an 8-millimeter-thick (0.3-inch) wall that leaned outward at dramatic angles. They found that the structure could remain stable even when tilted to 60 degrees, far steeper than the Leaning Tower of Pisa.  

While the current study focuses primarily on improving the printability of earthen materials, Srubar said scientists could use the same framework to test other biopolymers for enhanced properties such as strength and durability.

“There are some good indoor environmental benefits of having earth in a building,” said Samuel Armistead, a research associate in the Department of Civil, Environmental and Architectural Engineering. “It can regulate indoor moisture and uptake air pollutants. It can also serve as a thermal insulator, keeping things cool in the summer and warm in the winter.”

Construction projects often generate large amounts of excavated soil when workers dig foundations, basements, or parking structures. Much of that material ends up in landfills. 

“Our study suggests that there are ways to reuse waste earth material onsite, and that could largely reduce the environmental footprint of construction,” Armistead said.

Because clay and sand are widely available, Srubar said the team's findings could help builders around the world to tap into local resources. 

“Clay and sand are among the most abundant building materials on Earth,” Srubar said. “The science and engineering we're developing can be applied almost anywhere in the world.” 

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Journal

Nature Communications

DOI

10.1038/s41467-026-71885-z 

 

3D-printed earth-fiber objects by Lola Ben-Alon and the Natural Materials Lab were exhibited at the London Craft Week. 

Credit

Dan Weill

 

Illinois study explores feasibility of creating sustainable jet fuel from food waste

University of Illinois College of Agricultural, Consumer and Environmental Sciences

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Sabrina Summers and Yuanhui Zhang, University of Illinois Urbana-Champaign, hold vials of the sustainable aviation fuel developed in their lab.

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Credit: Marianne Stein/College of ACES

URBANA, Ill. – The aviation industry accounts for a large portion of global greenhouse gas emissions. Biobased, sustainable aviation fuel (SAF) can mitigate climate impacts, but transitioning to SAF faces critical supply chain constraints. A research team at the University of Illinois Urbana-Champaign has developed a method to produce jet-grade fuel from food waste, contributing to a circular bioeconomy. In a new paper, published in Nature Sustainability, they focus on technical and economic considerations.

In a previous study, the researchers outlined the process of developing SAF that meets aviation standards. This study follows the same general approach, converting food waste to crude oil through hydrothermal liquefaction (HTL), a process that mimics natural formation of crude oil in a fraction of the time, and refining it with a catalyst.

“However, here we use a simpler approach with less catalytic intensity and greater focus on distillation, which is commonly used for industrial purposes. This is a more economical and environmentally friendly method. But the quality of the fuel is not as good, and it needs to be mixed with regular jet fuel,” said corresponding author Yuanhui Zhang, Founder Professor in the Department of Agricultural and Biological Engineering (ABE), part of the College of Agricultural, Consumer and Environmental Sciences and The Grainger College of Engineering at the U. of I.

Zhang compared this to the use of ethanol for cars; it must be blended with fossil fuel to work in car engines.

“It would be very difficult to produce enough SAF to meet industry needs, so it makes sense to take a biodiesel approach with a percentage blend,” he explained. “Our tests are based on a 50-50 blend, so it will certainly be feasible to use a 10% or 20% blend of SAF with regular fuel.”

The researchers conducted tests on key parameters to ensure their SAF product meets jet fuel standards set by the American Society for Testing and Materials (ASTM) and the Federal Aviation Administration.

“We are still doing this work on a very small scale. But my lab is now set up to produce several liters of upgraded fuel, which is enough for diesel engine tests. After that, the next step will be jet engine tests,” Zhang said. 

The biggest bottleneck in SAF production is getting the waste from disposal to reclamation and recovery, Zhang noted. Most food waste ends up either in a landfill or a wastewater treatment plant, where it is separated and converted into sludge. Collecting and reusing food waste presents logistical challenges, but the HTL process enables use of treated wastewater as feedstock.

While HTL offers a promising approach to create SAF from wet waste, it leaves a toxic, nutrient-rich byproduct called HTL aqueous phase, or HTL-AP. Zhang and his team explored ways to recover acid and nutrients from HTL-AP through electrochemical (EC) treatment. 

The researchers also conducted techno-economic and lifecycle analysis for the integrated process of upgrading the biocrude oil and treating the HTL-AP byproduct. They developed three scenarios for the analysis: A baseline where HTL-AP was sent to a centralized wastewater treatment plant; treatment with EC technology to recover and valorize HTL-AP; and a future scenario based on improved EC technology. 

Compared to the baseline scenario, using EC technology nearly tripled the cost per gallon due to higher capital and operating costs. However, technological advances are expected to lower the EC costs, so they become equivalent to baseline in the future. 

The team also evaluated global warming potential (GWP), which indicates how much global warming is affected by CO2 emissions. They estimated that both the baseline and the improved EC treatment would be able to achieve negative carbon emissions, leading to lower GWP.

The study outlines a technically feasible and environmentally beneficial pathway for turning urban organic waste into SAF and promoting a circular bioeconomy, the researchers concluded.

The paper, “A circular hydrothermal refinery for sustainable aviation fuel from food waste,” is published in Nature Sustainability [DOI: 10.1038/s41893-026-01848-1].

Research in the College of ACES is made possible in part by Hatch funding from USDA’s National Institute of Food and Agriculture. This study was also supported by the National Science Foundation (award no. 1804453), the Department of Energy (project no. DE-EE0009269), and the 2115 Talent Development Program of China Agricultural University.

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Journal

Nature Sustainability

DOI

10.1038/s41893-026-01848-1 

Article Title

A circular hydrothermal refinery for sustainable aviation fuel from food waste

Article Publication Date

23-Jun-2026

 

Tracking melanoidins to improve food-waste biogas recovery

Maximum Academic Press

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By combining ultraviolet-visible spectroscopy, three-dimensional excitation-emission matrix fluorescence spectroscopy, parallel factor analysis, methane production tests, and microbial community analysis, the team found that higher hydrothermal temperatures continuously promoted melanoidin formation, especially above 140 °C. These compounds showed a clear dose-dependent inhibitory effect: low doses reduced digestion efficiency and methane quality, while high doses triggered near-complete system collapse.

Food waste is rich in organic matter and is widely considered a promising substrate for anaerobic digestion, a process that converts biodegradable materials into methane-rich biogas. Hydrothermal pretreatment is often used to accelerate the breakdown of complex food-waste components and overcome the slow hydrolysis stage of digestion. However, higher pretreatment temperatures can also promote Maillard reactions between sugars and amino compounds, generating melanoidins. Because melanoidins are structurally complex, difficult to isolate, and lack standard reference materials, their formation and biological effects have remained hard to quantify. These uncertainties have limited the optimization of hydrothermal pretreatment coupled with anaerobic digestion.

A study (DOI: 10.48130/een-0026-0008) published in Energy & Environment Nexus on 21 April 2026 by Guangsuo Yu’s & Lu Ding’s team, East China University of Science and Technology, reports that melanoidins increase with hydrothermal temperature and inhibit methane production by disrupting methanogenic microbial communities.

The researchers first prepared simulated food waste composed of cooked rice, pork, and cabbage, representing starch-rich, protein-rich, and cellulose-rich components. The waste was hydrothermally treated at 120, 140, 160, 180, and 200 °C for one hour, and the resulting hydrothermal liquid products were analyzed. Dissolved organic carbon increased up to 160 °C, indicating enhanced hydrolysis of macromolecules, but declined at higher temperatures as polymerization and condensation shifted carbon into less soluble products. Meanwhile, pH decreased from 5.62 to 3.59 as temperature increased, showing stronger acidification. The team then used UV-Vis spectroscopy to assess aromaticity and color-related absorption. SUVA254 and absorbance at 350 nm both rose markedly when temperatures exceeded 140 °C, indicating increased formation of aromatic, brown-colored melanoidin-like compounds. To strengthen semi-quantitative characterization, they applied three-dimensional fluorescence spectroscopy and parallel factor analysis. The model identified two fluorescent components, with Component 1 assigned mainly to melanoidins. Its maximum fluorescence intensity increased continuously from untreated samples to the 200 °C group, reaching 374.14 a.u., confirming that melanoidins accumulated progressively with hydrothermal severity. The researchers next prepared food-waste-derived melanoidins and added them to anaerobic digestion systems at four dosage levels: 2.08, 4.16, 6.24, and 8.32 mg·mL−1. Low-dose additions reduced methane content and impaired digestion performance without causing full acidification failure. In contrast, high-dose additions sharply suppressed methane production by 98.15% and 99.24%, with methane content dropping below 10% and final pH values falling well below the optimal range for methanogens. Microbial sequencing showed that melanoidins reshaped bacterial and archaeal communities. Bacterial groups related to acid fermentation remained active, but methanogenic archaea, including key methane-producing taxa, were strongly disrupted. This suggests that melanoidins mainly block the methane-production stage rather than the early acid-production stage.

Overall, the study reveals that hydrothermal pretreatment is a double-edged strategy for food-waste resource recovery. While it can enhance hydrolysis and accelerate substrate breakdown, excessive thermal severity promotes melanoidin accumulation, which weakens methane production and may collapse anaerobic digestion systems. By establishing a semi-quantitative approach for tracking melanoidins and linking dosage effects to microbial responses, the work offers practical guidance for selecting hydrothermal conditions that balance organic-matter solubilization with biological digestibility. Future applications may include pretreatment-temperature control, melanoidin monitoring, and microbial management strategies to improve stable biogas production from food waste.

###

References

DOI

10.48130/een-0026-0008

Original Source URL

https://doi.org/10.48130/een-0026-0008

Funding Information

This work was supported by the project of the National Key Research and Development Program of China (Grant No. 2022YFC3902404), and the National Natural Science Foundation of China (Grant No. 22278142).

About Energy & Environment Nexus

Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.

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DOI

10.48130/een-0026-0008 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Semi-quantitative characterization of melanoidins during hydrothermal treatment of food waste and their impact on anaerobic digestion

 

Researchers find evidence of daily body clock for humidity

Some insects' days are governed by humidity. Does it affect us, too?

University of Cincinnati

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Researchers at the University of Cincinnati found that fruit flies and other insects have a daily body clock tied to humidity. 

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Credit: Andrew Higley

In a novel experiment at the University of Cincinnati, researchers isolated kissing bugs, fruit flies, mosquitoes and spider beetles in a climate- and light-controlled environment and found that they responded predictably to cycles of humidity in the same way they do temperature and daylight. After the humidity cue was removed, the insects continued to respond to the cyclical fluctuations of humidity and dryness established in the experiment.

“They take humidity cues as a biological clock,” UC Professor Joshua Benoit said.

The study was published in the Nature journal Biological Timing and Sleep. It was supported with grants from the National Institute of Allergy and Infectious Diseases.

Circadian rhythms can affect everything from body temperature to hormones. But few studies have examined circadian rhythms for humidity, said lead author Shyh-Chi Chen, a former researcher in Benoit’s lab.

“Light and temperature are well-known environmental factors that can entrain the circadian clocks,” said Chen, now an assistant professor at Georgia College & State University. “Humidity, like light and temperature, fluctuates daily.”

For people, extremely high or low humidity is a mere annoyance. But for insects, it can mean life or death, Chen said.

“This could be critical for terrestrial organisms, as their survival depends on staying hydrated or avoiding dehydration,” Chen said.

So it’s useful for creatures to anticipate when conditions will be optimal to forage or otherwise expend energy, he said.

While the results were statistically significant, insects are less connected to humidity than daylight and temperature, researchers said. And mosquitoes showed the least behavioral connection to humidity.

Many animals respond to predictable cycles, such as the lunar calendar which also governs the tides, or the solar calendar, which governs the hours of daylight. UC researchers discovered that monarch butterflies rely on daylight as a sun compass to navigate on their epic continental migration.

Could mammals like us also take our cues from cycles of humidity?

Researchers said it’s possible, but the effects are probably far too miniscule to notice.

“While our current study focuses on animal models, it opens a fascinating door to human biology,” Chen said. “Although mammalian circadian biology is heavily dominated by the light-dark cycle, the potential for subtle, multisensory integration — including humidity — cannot be ruled out.”

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Journal

npj Biological Timing and Sleep

DOI

10.1038/s44323-026-00082-4 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Humidity as a potential zeitgeber for circadian entrainment of insect systems

Article Publication Date

22-Jun-2026

 

Researchers at the University of Cincinnati found that mosquitoes and other insects have a daily body clock tied to humidity. 

Credit

Andrew Higley

MUTUAL AID

Communication cues and signals are key to interspecies cooperation

Oregon State University

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NEWPORT, Ore. – Even in the animal world, teamwork requires communication – just ask the fish, dolphins, birds and butterflies who rely on other species for help with food, protection from prey and even parasite removal.

A new review of the behaviors of animals who engage in interspecies cooperation, a type of behavior where animals from different species work together for mutual benefit, shows that the information exchanged through cues and signals play an important role in this unique kind of teamwork.  

Researchers reviewed a dozen documented types of interspecies cooperation, ranging from fish that clean other fishes to ants that guard butterfly larvae and humans who work with honeyguide birds to find bee nests. They found a striking commonality across many of these interactions.

“We found that communication through cues and signals plays an important role in this relatively rare interaction; this helps animals work together in the moment,” said Kyra Bankhead, a doctoral student at Oregon State University’s Marine Mammal Institute and one of the study’s co-authors.

“Animals can use sounds, movements or other signals to inform decisions about whether, when or how to cooperate with one another.”

The findings were just published in the journal Animal Behaviour. The work was led by Mauricio Cantor, a behavioral ecologist with OSU’s Marine Mammal Institute; Katie Dunkley of the University of Oxford; Dominic Cram of the University of East Anglia; and Jessica van der Wal of the University of Cape Town, South Africa.

Within-species cooperation is well-documented and widespread, but less is known about interspecies cooperation, where animals must communicate effectively across species boundaries while coordinating complementary actions.

“We often think of communication as something that happens between members of the same species, but many animals also exchange information with entirely different species to achieve shared goals,” said Cantor, who has extensively studied the cooperative fishing behavior of dolphins and humans.

“These interactions remind us that cooperation is not limited to families, social groups or even members of the same species,” he said. “Studying how animals communicate across species boundaries helps us understand how cooperation evolves, and more generally, how interactions between species help shape the natural world.”

Animals tend to cooperate across species boundaries in a few areas: cooperative foraging or hunting, where animals work together to increase success; food-for-cleaning services, where a cleaner such as a fish or shrimp removes parasites from the bodies of “client” species, which aids the health of the client; food-for-protection services, where food is exchanged for protection from predators; and shelter-for-protection, where shelter is provided in exchange for predator protection services.

This new review of these behaviors clarifies the vital role communication plays in these interactions at three stages: identifying and/or attracting partners; initiating cooperation; and maximizing benefits of cooperation through coordination and preventing harm by one partner to the other.

For example, when humans and dolphins work together to find and collect fish, a dolphin gives the human a visual cue that discloses where the fish school is, indicating the right time and place to cast a fishing net, which aids the dolphin in catching its own fish as the net traps the fish.

While the new paper offers additional insights into interspecies communication, additional study is needed to better understand this behavior, the researchers said. Those questions include: how do naturally occurring cues and signals in interspecies cooperation compare to those in trained cooperative interactions, such as between humans and trained dogs, birds or other animals? And to what degree are these cues and signals learned or passed down through genetics?

“We still have many unanswered questions about this behavior, and hope this work will spur further research,” Bankhead said.

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Journal

Animal Behaviour

DOI

10.1016/j.anbehav.2026.123611 

Method of Research

Systematic review

Subject of Research

Animals

Article Title

The ecology and evolution of cues and signals in animal interspecies cooperation

Article Publication Date

18-Jun-2026

How animals communicate to work together across species boundaries

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