Do or dye: Synthetic colors in wastewater pose a threat to food chains worldwide

The ecological and health threats of synthetic dyes entering wastewater systems have been detailed in a new study, which calls for new laws worldwide on water management, and urgent investment in new sustainable treatment processes

Peer-Reviewed Publication

UNIVERSITY OF BATH

 

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SOURCE OF DYE CONTAINING WASTEWATER

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CREDIT: UNIVERSITY OF BATH

Dyes widely used in the textile, food and pharmaceutical industries pose a pressing threat to plant, animal and human health, as well as natural environments around the world, a new study has found.

Billions of tons of dye-containing wastewater enter water systems every year, and a group of researchers from the UK, China, Korea and Belgium say that new sustainable technologies including new membrane-based nano-scale filtration are needed to solve the issue, adding that legislation is needed to compel industrial producers to eliminate colourants before they reach public sewage systems or waterways.

Published today in Nature Reviews Earth & Environment, the study Environmental impacts and remediation of dye-containing wastewater was written by academics from the University of Bath, the Chinese Academy of Sciences, the Fujian Agriculture and Forestry University, the Korea Institute of Energy Technology (KENTECH), and KU Leuven, Belgium.

The research highlights that currently, up to 80% of dye-containing industrial wastewaters created in low- and middle-income countries are released untreated into waterways or used directly for irrigation. The authors say this poses a wide range of direct and indirect threats to human, animal and plant health.

Despite these ‘severe’ threats to health and ecosystems, the authors underscored that there is inadequate infrastructure, investment and regulatory effort for making dye usage more sustainable, or for treatment of dye-containing wastewater.

Dr Ming Xie, a lecturer in the Department of Chemical Engineering at the University of Bath (UK), believes that a multi-pronged approach is needed to combat the issue. He says: “Dyes create several problems when they reach water systems, from stopping light reaching the microorganisms that are the bedrock of our food chains, preventing their reproduction and growth, to more direct consequences like the toxic effects on plants, soils, animals and humans.

“There are several potential ways to remove dyes from water including chemical, biological and membrane-based techniques, but different dyes required different approaches, and once they reach wastewater systems treatment processes can be highly energy intensive.

“A worldwide regulatory effort is needed to stop dyes reaching wastewater or other water systems such as irrigation. Given the complexity of treating dye-containing wastewater, one solution would be to shift from the concept of centralised or regional treatment methods, to decentralised and site-specific treatment at source, by compelling industries to remove dyes from the wastewater they create before it reaches public water systems.”

Textile industry is biggest dye consumer

Mauveine, the first organic synthetic dye, was discovered in 1865, spurring the creation of the global dye industry. Since then, more than 10,000 different types of dyes have been synthesized, with annual global production today estimated at 1 million tons.

Dyes are used in the rubber, leather tanning, paper, food, pharmaceuticals and cosmetic industries, while the biggest user, the textile business, consumes 80% of produced synthetic dyes and generates about 70 billion tons of dye-containing wastewater annually.

China, India and Bangladesh combined discharge around 3.5 billion tons of textile wastewater each year. Water contamination is aggravated by synthetic dyes, which in light of water scarcity issues, makes dyes a fundamental environmental and sustainable development issue.

Untreated dyes cause colouration of water bodies, reducing the degree of visible light that passes through the surface layer – hindering photosynthesis for aquatic plants and creating impacts along the food chain.

Microalgae, which form the foundation of the aquatic food chain, are most sensitive to photosynthesis reduction, suffering growth inhibition and cell deformation when exposed to a synthetic dye. This effect, and the knock-on suppressed transfer of energy and nutrients up the food chain, could lead to breakdown of entire aquatic ecosystems.

The effects have also been observed in fish. Dyes can deposit in fishes’ gills, lateral lines or brains, leading to toxicological effects such as uncoordinated movement, respiratory distress, liver damage and kidney dysfunction. These effects not only reduce the nutritional value of the fish to predators, but also lower their reproductive rates. Toxic dyes can also bioaccumulate in the fishes’ fatty tissue, presenting health risks to humans and animals throughout the food chain.

Negative impacts of dyes are also found on land – where they disturb the balance of microbial communities in soil – and in humans. Exposure to dyes can trigger allergies, asthma and diseases including dermatitis and central nervous system disorders, as well as organ dysfunction and increased cancer risk.

No single treatment offers solution

The review explores the variety of remediation technologies for dye-containing wastewater, including chemical, biological, physical and emerging advanced membrane-based techniques. The authors found that no single technique presents a ‘silver bullet’ for removing dyes, while several promising methods are not yet technologically ready at scale.

In light of this, they suggest a collective effort, led by policymakers, to increase the adoption of advanced remediation technologies and change textile processing methods to minimize the use of the most toxic dyes.

The authors also highlight a potential commercial impetus - the scope for industries to create new revenue streams from the processing, separation and reuse of wastewater materials.

Co-author Dr Dong Han Seo, from the KENTECH Energy Materials and Devices/Environmental and Climate Technology Track, says: “Dye containing wastewater is one of the most challenging wastewater streams, which impacts lives and the environment in several countries. Our review provides the latest insight on how we can effectively manage the challenge from the perspective of circular economy, effectively recycling dyes from wastewaters using treatment strategies such as advanced membrane-based separation to recover both useful dyes as well as clean water.”

Dr Jiuyang Lin, from the Chinese Academy of Sciences, adds: “This review provides the examples on how we can reduce the dye footprints from production stages using new dyeing techniques. Guidance on effective solutions to dye containing wastewaters could be used to treat other challenging wastewater streams, safeguarding lives and the environment for future generations.”

 

ENDS

For more information or to request interviews, contact Will McManus in the University of Bath press office at wem25@bath.ac.uk or press@bath.ac.uk.

The research paper is available at: https://doi.org/10.1038/s43017-023-00489-8

Images from the paper are available at: https://tinyurl.com/yswjwh8h

The University of Bath 

The University of Bath is one of the UK's leading universities for high-impact research with a reputation for excellence in education, student experience and graduate prospects. 

We are named ‘University of the Year’ in The Times and The Sunday Times Good University Guide 2023, and ranked among the world’s top 10% of universities, placing 148th in the QS World University Rankings 2024. We are ranked 5th in the UK in the Complete University Guide 2024, 6th in the Guardian University Guide 2024 and 8th in the The Times and Sunday Times Good University Guide 2024. 

Bath is rated in the world’s top 10 universities for sport in the QS World University Ranking by Subject 2023. We produce some of the world’s most job-ready graduates and were named University of the Year for Graduate Jobs by the Daily Mail University Guide 2024, as well as ranking as one of the world’s top 90 universities for employer reputation according to the QS World University Rankings 2024.

Research from Bath is helping to change the world for the better. Across the University’s three Faculties and School of Management, our research is making an impact in society, leading to low-carbon living, positive digital futures, and improved health and wellbeing. Find out all about our Research with Impact: https://www.bath.ac.uk/campaigns/research-with-impact/

 

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JOURNAL

Nature

DOI

10.1038/s43017-023-00489-8 

METHOD OF RESEARCH

Systematic review

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Environmental impacts and remediation of dye-containing wastewater

ARTICLE PUBLICATION DATE

26-Oct-2023

COI STATEMENT

The authors declare no competing interests.

 

Financial insecurity common among frontline healthcare workers during COVID-19

Peer-Reviewed Publication

UNIVERSITY OF NORTH CAROLINA AT GREENSBORO

Many frontline health care workers in the United States experienced food insecurity and other significant financial challenges during the COVID-19 pandemic, according to a recent study led by UNC Greensboro (UNCG) researcher Mathieu Despard and published in Compensation & Benefits Review.

Despard said he and his collaborators – Dr. Haotian Zheng and Dr. Sophia Fox-Dichter at Washington University in St. Louis – were surprised by their findings, especially their discovery that a higher salary did not necessarily shield a health care worker from struggling to make ends meet. 

“You can be a frontline healthcare worker with a college degree and making decent money within healthcare, but that does not mean that you’re not going to have problems like trouble paying your rent,” Despard said.

Among 2321 frontline healthcare workers, whose incomes ranged from less than $25k to over $75k, one-third experienced food insecurity, one-fifth had difficulty paying their bills and medical care hardship, and one-quarter experienced housing hardship.

Despard said multi-pronged pressures contribute to healthcare workers’ financial difficulties across salary ranges. “Income only tells part of the story,” he says. “We’re talking about people who may be struggling with student debt, childcare, and unaffordable housing.”

The researchers also investigated an often-overlooked factor in assessments of financial wellbeing: workers’ access to benefits. 

“When we have this conversation about a living wage, we tend to think in terms of pay,” Despard says. “We tend not to think in terms of the number and quality of benefits, yet benefits are 31% of total compensation.”

The researchers examined whether access to a variety of benefits – including health and dental insurance, paid time off, and retirement – were related to nine different measures of financial insecurity.

Their results indicate that frontline healthcare workers’ access to benefits is strongly related to financial insecurity, with workers with less access to benefits having higher levels of financial insecurity, even when controlling for income.

The relationship between benefits and financial insecurity was strongest among healthcare workers without a college degree who work in private duty settings, such as home health aides.

Despard said these findings have key applications for both employers and employees. By providing ample benefits, employers can help mitigate healthcare workers’ financial insecurity. Healthcare workers on the job market can also heed these findings by closely considering not only a job’s salary but also the benefits available.

“The takeaway is workers need to pay attention to benefits, not just pay,” Despard said. “But employers need to do a much, much better job of making all of that information more transparent and easier to understand.”

 

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JOURNAL

Compensation & Benefits Review

DOI

10.1177/08863687231189 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Access to Employer Benefits and Financial Insecurity Among Frontline Healthcare Workers

 

New data: Car buyers are more likely to consider an electric vehicle if their neighbors drive one

First-of-its-kind “Peer Influence and Electric Vehicle Adoption” report pinpoints EV hotspots in 11 cities linked to neighborhood effect

Reports and Proceedings

GENERATION180

 

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COVER PHOTO OF NEW REPORT ILLUSTRATING PEER INFLUENCE ON EV ADOPTION

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CREDIT: GENERATION180

New York, NY — A new report from Generation180, a national, clean energy nonprofit, finds that car buyers are more likely to consider an electric vehicle if their neighbors drive one. While multiple factors can influence purchasing decisions, this analysis of new EV retail registrations over a five-year period finds that EV ownership is highly concentrated in key hotspots – indicating the influence of a “neighborhood effect” on EV adoption.

In the report, Peer Influence and Electric Vehicle Adoption, researchers performed geospatial analysis to determine EV registration “hot spots” for 2018 and 2022, for a 5-year look. The maps in the report demonstrate the presence of a “hot spot” (zip codes with high concentrations of EV registrations per capita), whereas a “cold spot” indicates regions with low EV registration clusters. However, even in areas with below-average growth, researchers found concentrations indicating a neighborhood effect. EV retail registration data was provided by, and analysis performed using data and insight commissioned from S&P Global Mobility.

“This new report shows how an individual’s personal influence really matters when it comes to encouraging clean energy behaviors like driving electric. And the collective actions of individuals can add up to make a big impact,” said Stuart Gardner, Program Director, Electrify Your Life, Generation180. 

This report represents the first time that this type of cluster analysis has been conducted broadly across key U.S. markets to identify zip codes experiencing high EV registration per capita, while accounting for the neighborhood effect. 

During the study period (2018-2022), this report shows that: 

• Analyses of new retail vehicle registrations in 11 cities, or “designated market areas” (DMAs) studied, indicate strong evidence of a peer effect influence on the growth in EV sales.
• EV registrations experienced significant growth across all 11 DMAs studied.
• Compared to the national average growth (328%), the following cities saw:
  • Above national average growth: Miami (571%), New York City (479%), Charlotte (476%), Philadelphia (426%), Austin (377%), Los Angeles  (357%)
  • Below national average growth: Washington, DC: (319%), Raleigh-Durham (316%), Atlanta (295%), Denver (253%), Seattle (226%).
• Interviews with EV owners, highlighted in ten case studies, illustrate the peer effect qualitatively, including stories about the benefits of driving electric shared by commuters, parents, urban and suburban drivers, and others. 

While other factors, such as income, education, age, and product availability, can influence whether someone buys an EV, researchers say, these concentrations of high EV registrations in zip codes point to a neighborhood effect as a significant factor. 

“A growing body of evidence finds that if your neighbors adopt clean energy behaviors, you will too,” said Kenneth Gillingham, Professor of Economics, Yale University. “This report is the latest to point to the role of a contagion effect of the good kind. Unlike a pandemic, this contagion can lead peers and neighbors to influence each other to adopt greener technologies.”

“There is unprecedented momentum for clean energy right now in our country,” said Wendy Philleo, Executive Director, Generation180. “As we find ourselves in the ‘decisive decade’ for climate action and emissions reduction, tapping the power of peer influence should be considered more widely as a strategy for helping us achieve a clean energy future for all.”

As governments, EV advocates, and the auto industry look to promote the uptake of electric vehicles, in part to support reductions in carbon emissions, this report provides an important benchmark. With millions of financial incentives available over the coming decade through the U.S. Inflation Reduction Act, the country must ensure that all Americans are able to benefit from EV adoption.

For more information on the report, study methodology, and Generation180, please visit generation180.org.

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METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

 

Virginia Tech awarded $2 million to advance groundwater availability and quality

Mark Widdowson and a team of interdisciplinary researchers will advance aquifer monitoring research to help communities design safe practices for ensuring sustainable groundwater.

Grant and Award Announcement

VIRGINIA TECH

 

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MARK WIDDOWSON.

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CREDIT: MARK WIDDOWSON. PHOTO BY PETER MEANS FOR VIRGINIA TECH.

Groundwater is a necessary resource for communities around the world, but in some areas, it’s being depleted faster than it’s being recharged naturally. Is sustainable groundwater possible? The answer is yes, and Virginia Tech is leading an effort to solve this water security crisis.

Researchers from the College of Engineering have been awarded $2 million from the U.S. Environmental Protection Agency to research the use and risks of enhanced aquifer recharge to improve groundwater availability and quality. With the funding, part of a larger $7,837,196 award to four institutions, Virginia Tech is developing a web-based decision-support tool to guide communities, agencies, and practitioners in designing safe and sustainable implementation methods that replenish existing groundwater and restore streamflow.

Mark Widdowson, principal investigator and department head of the Charles E. Via, Jr. Department of Civil and Environmental Engineering, will lead a team of researchers to advance safe and sustainable implementation of enhanced aquifer recharge in the U.S. coastal plain and equivalent hydrogeologic settings throughout the world.

“Our project team of engineers and scientists aims to advance sustainable groundwater usage by addressing recharge risk and performance factors,” said Widdowson. “We are committed to solutions for safe drinking water and economic growth that are protective of the public and the resource.”

Joining Widdowson are co-principal investigators Amy Pruden and Jingqui Liao from civil and environmental engineering, Madeline Schreiber and Ryan Pollyea from the Department of Geosciences in the College of Science, and Kang Xia from the School of Plant and Environmental Sciences in the College of Agriculture and Life Sciences.

Widdowson has firsthand experience with successful aquifer recharge as co-director of the Potomac Aquifer Recharge Monitoring Laboratory in Hampton, Virginia. He works with graduate students, faculty, and Hampton Road Sanitation District (HRSD) engineers on research related to advanced water treatment, aquifer recharge, and groundwater monitoring.

Groundwater withdrawals by companies, municipalities, and homeowners in eastern Virginia have diminished the groundwater supply in the Potomac Aquifer, making the region vulnerable to land subsidence, sea-level rise, and saltwater intrusion. The aquifer’s groundwater is a limited natural resource because the surrounding clay and bedrock prevent water from recharging naturally.

The Sustainable Water Initiative for Tomorrow (SWIFT) is a managed aquifer recharge initiative that will take highly treated wastewater that would normally be discharged into surrounding rivers and put it through additional advanced water treatment to produce water that matches existing groundwater chemistry throughout eastern Virginia. That will enable the water supply to remain productive for generations to come by repurposing wastewater into groundwater. The sanitation district is currently recharging the aquifer with as much as 1 million gallons of repurposed water per day.  

“Our approach builds on the experience of our team with the ongoing demonstration of enhanced aquifer recharge at the SWIFT Research Center in partnership with HRSD,” said Widdowson. “We are honored to have this opportunity to translate practical knowledge in support of greater water security and improved groundwater quality.”

 

Community-developed guidelines for publishing images help address reproducibility problem in science

Peer-Reviewed Publication

ROCKEFELLER UNIVERSITY

Images created by a plethora of high-tech instruments are widely found in scientific research as both illustrations and sources of data. Recent advancements in light (or optical) microscopy in particular have enabled sensitive, fast, and high-resolution imaging of diverse samples, making image use in scientific papers more popular than ever.

And yet there are no common standards for the publication of images. This causes major snags in an essential element of the scientific process: reproducibility. Any researcher looking to replicate the results of a study without full information on how images key to those results were produced has an impossible task before them.

“A lot of imaging scientists around the world have been very concerned by the reproducibility crisis,” says Alison North, senior director of the Bio-Imaging Resource Center (BIRC) at Rockefeller University. “People publish so little information about how they acquire their images and how they analyze them.”

That’s why an international consortium of experts, including North and BIRC image analyst Ved Sharma, recently put together easy-to-follow guidelines for publishing images and image analyses born of their collective knowledge of best practices. These guidelines were recently published in an open-access study in Nature Methods.

The guidelines were assembled in a two-year project involving dozens of imaging scientists from QUAREP-LiMi (Quality Assessment and Reproducibility for Instruments & Images in Light Microscopy), a group that includes 554 members from 39 countries.

They include practical checklists for scientists to follow with the goal of publishing fully understandable and interpretable images.

Each checklist is divided into three levels: minimal, which describes essential requirements for reproducible images; recommended, which bolsters image comprehensibility; and ideal, which includes top-tier best practices.

For example, the checklist includes standards for formatting, color handling, and annotation. Indicating the origin of an inset from an image is minimal; providing intensity scales for grayscale, color, and pseudocolor is recommended; and annotating image details such as pixel size and exposure time are ideal.

North says, “We advise everyone to publish their images in black and white rather than color, because your eye is much more sensitive to details in monochrome. Many investigators like color images because they’re pretty and they look impressive. But they don’t realize they’re actually throwing away a lot of information.”

The image-analysis checklists cover three different kinds of workflows: established, new, and machine-learning. Citing each step is a minimal requirement of an established workflow, for example, while providing a screen recording of or tutorial for a new workflow is ideal.

This is especially relevant because NIH-funded researchers now have to include data management protocols to meet the requirements of the new NIH data management policy, North says. “People have been saying, ‘What are we supposed to write in that?’ This paper gives them those guidelines.”

That scientists have a clearly articulated image-analysis workflow is important for scientific journals as well; as the primary disseminators of scientific knowledge, journals have a vested interest in ensuring that the papers they publish are transparent about how results were produced. To that end, journal editors took part in discussion with the study authors.

The guidelines can only increase accessibility to the data in a paper, Sharma says. “There is so much information that could be included for each image in a paper, but most of the time it’s not available, or the reader has to dig deep into the paper to find out where the information is in order to make sense of the image,” Sharma says. “If scientists start adopting even the minimal standard for image publication, reproducibility would be so much easier for everyone.”

 

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JOURNAL

Nature Methods

DOI

10.1038/s41592-023-01987-9 

 

A potentially cheaper and 'cooler' way of hydrogen transport

Researchers develop a compound that can store hydrogen energy at room-temperature for an extended period of time

Peer-Reviewed Publication

KYUSHU UNIVERSITY

 

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COMPARISON OF THE HYDROGENASE CYCLE FOUND IN NATURE WITH THE COMPOUND DEVELOPED IN THE STUDY. HYDROGENASES EXTRACT AN ELECTRON FROM A SINGLE HYDROGEN MOLECULE AT ROOM TEMPERATURE FOR USE IN OTHER BIOLOGICAL PROCESSES. THE COMPOUND DEVELOPED IN THE CURRENT STUDY UNDERGOES A SIMILAR PROCESS TO STORE ELECTRONS FROM HYDROGEN.

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CREDIT: KYUSHU UNIVERSITY/OGO LAB

Fukuoka, Japan—In the continued effort to move humanity away from fossil fuels and towards more environmentally friendly energy sources, researchers in Japan have developed a new material capable storing hydrogen energy in a more efficient and cheaper manner. The new hydrogen energy carrier can even store said energy for up to three months at room temperature. Moreover, since the material is nickel based, its cost is relatively cheap. The results were reported in Chemistry—A European Journal.

As humanity combats the ongoing climate crisis, one avenue researchers focus on is the transition into alternative sources of energy such as hydrogen. For several decades now Kyushu University has been investigating ways to more efficiently use and store hydrogen energy in the effort to realize a carbon neutral society.

"We have been working on developing new materials that can store and transport hydrogen energy," explains Professor Seiji Ogo of Kyushu University's International Institute for Carbon-Neutral Energy Research who led the research team. "Transporting it in its gaseous state requires significant energy. An alternative way of storing and transporting it would be to 'split-up' the hydrogen atoms into its base components, electrons and protons."

Many candidates have been considered as possible hydrogen energy carries such as ammonia, formic acid, and metal hydrides. However, the final energy carrier had not yet been established.

"So, we looked to nature for hints. There are a series of enzymes called hydrogenases that catalyze hydrogen into protons and electrons and can store that energy for later use, even at room temperature," continues Ogo. "By studying these enzymes our team was able to develop a new compound that does exactly that."

Not only was their new compound able to extract and store electrons at room temperature, further investigations showed that it can be its own catalyst to extract said electron, something that had not been possible with previous hydrogen energy carriers. The team also showed that the energy could be stored for up the three months.

Ogo also highlights the fact that the compound uses an inexpensive element: nickel. Until now, similar catalysts have used expensive metals like platinum, rhodium, or iridium. Now that nickel is a viable option for hydrogen energy storage, it can potentially reduce the cost of future compounds.

The team intends to collaborate with the industrial sector to transfer their new findings into more practical applications.

"We would also like to work on improving storage time and efficiency as well as investigate the viability of cheaper metals for such compounds, " concludes Ogo. "Hopefully our findings will contribute to the goal of decarbonization so that we can build a greener and environmentally friendly future."

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For more information about this research, see "Single-Step Synthesis of NiI from NiII with H2," Chiaki Takahashi, Takeshi Yatabe, Hidetaka Nakai, and Seiji Ogo, Chemistry—A European Journal, https://doi.org/10.1002/chem.202302297

About Kyushu University 
Kyushu University is one of Japan's leading research-oriented institutes of higher education since its founding in 1911. Home to around 19,000 students and 8,000 faculty and staff, Kyushu U's world-class research centers cover a wide range of study areas and research fields, from the humanities and arts to engineering and medical sciences. Its multiple campuses—including one of the largest in Japan—are located around Fukuoka City, a coastal metropolis on the southwestern Japanese island of Kyushu that is frequently ranked among the world's most livable cities and historically known as Japan's gateway to Asia. Through its Vision 2030, Kyushu U will 'Drive Social Change with Integrative Knowledge.' Its synergistic application of knowledge will encompass all of academia and solve issues in society while innovating new systems for a better future.

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JOURNAL

Chemistry - A European Journal

DOI

10.1002/chem.202302297 

METHOD OF RESEARCH

Experimental study

ARTICLE TITLE

Single-Step Synthesis of NiI from NiII with H2

 

Inspection method increases confidence in laser powder bed fusion 3D printing

Peer-Reviewed Publication

DOE/OAK RIDGE NATIONAL LABORATORY

 

IMAGE: 

ORNL RESEARCHER ZACKARY SNOW COMPARES DATA FROM DIFFERENT TYPES OF IMAGES COLLECTED DURING AND AFTER METAL PARTS WERE ADDITIVELY MANUFACTURED USING A POWDER BED PRINTER LIKE THE ONE BEHIND HIM.

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CREDIT: CARLOS JONES/ORNL, U.S. DEPT. OF ENERGY

Researchers at the Department of Energy’s Oak Ridge National Laboratory have improved flaw detection to increase confidence in metal parts that are 3D-printed using laser powder bed fusion. This type of additive manufacturing offers the energy, aerospace, nuclear and defense industries the ability to create highly specialized parts with complex shapes from a broad range of materials. However, the technology isn’t more widely used because it’s challenging to check the product thoroughly and accurately; conventional inspection methods may not find flaws embedded deep in the layers of a printed part.

ORNL researchers developed a method that combines inspection of the printed part after it is built with information collected from sensors during the printing process. The combined data then teaches a machine-learning algorithm to identify flaws in the product. Even more significantly, this framework allows operators to know the probability of accurate flaw detection just as reliably as traditional evaluation methods that demand more time and labor.

“We can detect flaw sizes of about half a millimeter — about the thickness of a business card – 90% of the time,” said ORNL researcher Luke Scime. “We’re the first to put a number value on the level of confidence possible for in situ (in process) flaw detection.” By extension, that reflects confidence in the product’s safety and reliability.

Laser powder bed fusion, the most common metal 3D-printing process, uses a high-energy laser to selectively melt metal powder that has been spread across a build plate. Then the build plate lowers before the system spreads and melts another layer, slowly building up the designed product.

Engineers know there will be flaws in the material.

“For regular manufacturing we know what those are and where and how to find them,” said ORNL researcher Zackary Snow. “(Operators) know the probability that they can detect flaws of a certain size, so they know how often to inspect to get a representative sample.”

3D printing has not benefited from the same confidence.

“Not having a number makes it hard to qualify and certify parts,” Snow said. “It’s one of the biggest hurdles in additive manufacturing.”

A paper by ORNL researchers and partner RTX, recently published in Additive Manufacturing, explains the process they developed to arrive at a 90% detection rate while reducing the probability of false positives, which can lead to scrapping good products.

For the first research step, aerospace and defense company RTX designed a part similar to one it already produces, providing opportunities to see realistic-looking flaws. Then, RTX 3D-printed the part multiple times monitoring during the build with a standard near-infrared camera and an added visible-light camera. Both RTX and ORNL researchers conducted quality inspections afterward using X-ray computed tomography, commonly called CT scans.

With consultation from RTX, ORNL additive manufacturing experts aligned the data into a layered stack of images, which essentially became the textbook for the machine-learning algorithm. During training, the algorithm took a first pass at labeling flaws using the CT scan images. Then a human operator annotated the rest based on visual cues in data collected during the printing process. Human feedback continues to train the software, so the algorithm recognizes flaws more accurately each time. Previous ORNL advances in in-situ monitoring and deep-learning frameworks were used as tools in this novel approach. Over time, this will reduce the need for human involvement in manufacturing inspection.

“This allows CT-level confidence without CT,” Snow said. A common method for checking some 3D-printed parts, CT imaging and analysis drives up costs because it requires extra time and expertise. Plus, CT cannot effectively penetrate dense metals, limiting its application.

When the algorithm is applied to a single design consistently manufactured with the same material and process, it can learn to provide consistent quality analysis within days, Scime said. At the same time, the software incorporates all that it learns from different designs and constructions, so it will eventually be able to accurately check products with unfamiliar designs.

The ORNL-developed inspection framework could help in expanding additive manufacturing applications. With statistically verified quality control, additive manufacturing could become viable for mass-producing products like car parts, Snow said.

It could also diversify the types of parts that can be 3D printed. Certainty about the smallest detectable flaw size allows more design freedom. This is important because the industry is already headed toward larger print volumes and faster print rates – meaning more lasers interacting to create bigger parts with different types of flaws, said Brian Fisher, senior principal engineer for additive manufacturing at RTX’s Raytheon Technologies Research Center.

“You can really start to save time and money and make a business case when printing larger assemblies – except those are also the hardest to inspect today,” Fisher said. “The vision is with additive, we can make large, highly-complex parts in very dense materials, which traditionally would be very difficult and expensive to thoroughly inspect.”

Next, the ORNL team will train the deep-learning algorithm to better differentiate between types of irregularities and to categorize flaws that have multiple causes.

Additional ORNL researchers who contributed to the project also include Amir Ziabari and Vincent Paquit. The research was sponsored by DOE's Advanced Materials and Manufacturing Technologies Office, or AMMTO, with support from RTX and took place at DOE's Manufacturing Demonstration Facility. 

UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

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JOURNAL

Additive Manufacturing

DOI

10.1016/j.addma.2023.103817 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Scalable in situ non-destructive evaluation of additively manufactured components using process monitoring, sensor fusion, and machine learning