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Sewage could be purified for drinking and extracted as treasure


Wastewater treatment produces toxins, but scientists think they can turn them into treasure.

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In a world where one in four people still do not have access to safe drinking water – a disproportionate amount of which resides in poor areas – scientists have routinely found ways to purify wastewater so it can be added to humanity’s fresh water supply.

A mechanism, called anaerobic filtration, led the charge because it uses very little energy to convert a large amount of wastewater into a consumable form. But there is a glaring problem. When cleaning water, anaerobic filtration tends to create dangerous by-products called sulfides. These are extremely harmful to our health and polluting the environment.

The Centers for Disease Control and Prevention, for example, writes that inhaling hydrogen sulfide can lead to symptoms such as difficulty breathing, tremors, eye and skin irritation, loss of consciousness and, at high concentrations, even death. You only need to be close enough to the chemical to breathe it in, which means on-site workers at wastewater treatment plants are directly in the line of sight.

Focusing on this pressing dilemma, in an article published Wednesday in the journal ES&T Engineering, Stanford researchers reveal a way to reframe the so-called cost of anaerobic filtration as a hidden treasure. Not only has the team developed an intriguing way to transform toxic wastewater-based sulfides into safe compounds, but also into highly valuable resources for agricultural and refillable technologies.

“We are always looking for ways to close the loop on chemical manufacturing processes,” Will Tarpeh, assistant professor of chemical engineering at Stanford University and lead author of the study, said in a statement.

Typically, according to the study, scientists attempt to solve the sulfide problem by using certain chemicals to separate sulfur derivatives into non-toxic components. But this, according to the researchers, often corrodes the pipes of the purification system, reducing the overall efficiency of producing clean water.

The team behind the new study, meanwhile, is dealing with sulfides using what’s called electrochemical sulfur oxidation. “The process I’m working on involves electrochemically converting sulfides from wastewater into something more valuable, such as sulfuric acid, which can be used in many manufacturing processes as well as in fertilizers,” Xiaohan said. Shao, Ph.D. civil and environmental engineering student at Stanford University and lead author of the study, said in a video presentation of the study.

Basically, this electrochemical system gives researchers the ability to transform toxic sulfides into other sulfur derivatives, thereby completely removing the threatening chemical from anaerobic filtration. According to the team, this procedure requires so little energy that it could be powered entirely by renewable sources and be applied to the wastewater supply of entire cities.

“We can integrate our process with other advanced wastewater treatment technologies to [make] the gap between wastewater and drinking water is smaller,” Shao said in the video presentation. it will help agriculture – and manufacturing, you will [reduce] consumption of raw materials.

Part of the group of scientists aiming to address water shortages around the world, some of which are focusing on stand-alone solar panel systems that extract water from the air, Shao remarked, “Hopefully this study will help to accelerate the adoption of technology that mitigates pollution. , recovers valuable resources and creates clean drinking water at the same time.”

CNET

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