Jun 19, 2019 | Updated: 09:31 AM EDT

Sewers Could Help Clean Our Atmosphere

May 02, 2019 11:16 AM EDT

Princeton team
(Photo : Princeton University)

Last year, December 18, in an article published in the journal, Nature Sustainability, researchers at Princeton University identified several potentially viable paths to use sewage water as a carbon sink, which basically means using sewage water to clean the atmosphere while undergoing treatment. They reasoned out that in most cases, sewer plants are already located near industrial facilities that emit large quantities of carbon dioxide, thus it only makes sense to try and develop methods to use wastewater to capture enough carbon to offset the amount that these plants initially generated.

In a very recent breakthrough, one which was published in Energy & Environmental Science, the same team, led by Zhiyong Jason Ren, professor of civil and environmental engineering and the Andlinger Center for Energy and the Environment at Princeton, was finally able to come up with the technology to do just this.

The researchers chose wastewater from breweries, wherein they ran the wastewater through a specially designed chamber with a black silicon interface that splits water and isolates the hydrogen gas. The splitting process itself was aided by sunlight and bacteria that generates an electrical current, and in a process called photocatalysis, organic compounds breakdown and the pure hydrogen bubbles up. Besides treating and cleaning the water, the hydrogen it produces can then be combined with carbon or nitrogen to create high-value chemicals such as methanol and ammonia.

For such a long now, the creation of hydrogen has relied on fuel (oil, gas, or coal), all of which are extremely energy-intensive and this particular development would be very much appealing to refineries and chemical plants since not only will they be able to save on wastewater treatment, but they'd be saving on energy usage as well.

"It's a win-win situation for chemical and other industries," said LuLu, the first author on the study and an associate research scholar at the Andlinger Center, since they were able to analyze initially the potential environmental and economic benefits of implementing such a change. Millions of tons of CO2 could be captured and used to generate revenue.

According to the researchers, this is the first time that hydrogen has been produced out of wastewater. They were able to produce the gas continuously over four days until the wastewater ran out, which is significant, according to them because previously designed systems have failed after a couple of hours.

Ren also mentioned that from a pilot scale, given the design, the technology they're presenting is completely scalable and cost-effective and may be recreated at an industrial level.

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