A team of scientists from Chinese research institutes has managed to use bacteria to purify wastewater from organic pollutants and obtain a series of chemical compounds for the semiconductor industry. This process could pave the way for sustainable and environmentally friendly production of valuable semiconductor materials. The results of the research were published in the peer-reviewed journal Nature Sustainability on October 16.

Research led by Professor Gao Xiang of the Shenzhen Institute of Synthetic Biology of the Chinese Academy of Sciences and Professor Lu Lu of the Harbin Institute of Technology in Shenzhen has revealed the possibility of obtaining materials used to make semiconductors from sewage-modified bacteria. Researchers have succeeded in converting wastewater pollutants into semiconductor biohybrids composed of biological and non-biological components.

The research team chose the marine microorganism Vibrio natriegens as the starting point for modifying bacteria. According to scientists, “These are some of the fastest-growing bacteria that thrive in high-salt environments and are very resistant to sewage. They can utilize more than 200 organic substances as nutrients, including sugars, alcohols, amino acids and organic acids, making them ideal candidates for this research.” brings it.”.

The team then “rebooted” the sulfate reduction mechanism of Vibrio natriegens by teaching the species to take up sulfate directly from the environment and produce hydrogen sulfide; this was then combined with metal ions in the wastewater to form semiconductor nanoparticles. The method proved to be versatile and can be applied to a variety of metal ions, yielding compounds such as cadmium sulfide, lead sulfide and mercury sulfide.

Semiconductor biohybrids were created by fixing nanoparticles to the surface of bacteria. The semiconductor material absorbed solar energy under the influence of light and converted it into electrons, providing additional energy to the bacteria. In a laboratory experiment using biohybrids to treat wastewater, 99% of cadmium ions were removed in the form of cadmium sulfide particles.

Such nanoparticles, also known as quantum dots, were the centerpiece of a discovery that won another group of scientists this year’s Nobel Prize in Chemistry. “After a complete cycle, biohybrids in wastewater can be collected by filtration or sedimentation (sedimentation of particles) to obtain semiconductor materials., – reported Gao Xiang. — “This system could become an effective and cost-effective method of producing extremely valuable quantum dots.”

When biohybrids grow in wastewater, they also convert organic pollutants into 2,3-butanediol (BDO), a valuable chemical widely used in cosmetics, agriculture and healthcare. Laboratory tests showed that with artificial lighting, biohybrids produced BDO twice as fast as unmodified bacteria, and carbon conversion rates increased by 26%.

“The additional energy produced by nanoparticles through light absorption increased the efficiency of biohybrid synthesis and the rate of conversion of organic substances in wastewater. Traditionally, all the energy required for bacterial growth and BDO production is provided by the bacteria themselves, including self-metabolism and digestion of organic matter.” “The additional energy gained by absorbing light apparently speeds up both processes.” Gao explained.

In an experiment conducted in a 5-liter reactor, biohybrids were successfully grown using real industrial wastewater, achieving a BDO efficiency of 13 grams per liter, exceeding the results of all previous studies.

Scientists are currently working on possibilities to scale up the process. The main obstacle is the poor transparency of industrial wastewater. Therefore, reactors with larger surface areas that will provide sufficient illumination for the active activity of bacteria are needed.

“Semiconductor biohybrids combine the best properties of biological integral catalysts and semiconductor nanomaterials, allowing non-photosynthetic industrial microbial cell plants to harness solar energy for chemical production,” the researchers concluded.. Source