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Danish technology purifies pharmaceutical wastewater sustainably

Researchers at the Technical University of Denmark have developed a better and more cost-effective solution to purify pharmaceutical wastewater.

The technology patented by the researchers comprises a novel microbial electrochemical ultraviolet cell that integrates the microbial management of hydrogen peroxide with ultraviolet radiation to produce hydroxyl radicals. These radicals can efficiently remove the organic pollutants from pharmaceutical wastewater, thus making the water pure and safe for the environment.

“Our method uses a very efficient and sustainable living system to drive the degrading of residual pharmaceutical components,” says Yifeng Zhang, Associate Professor, Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby.

Bacteria harness energy for purifying wastewater

Bacteria that use domestic wastewater as a food source are the key to the new invention. These bacteria are ubiquitous in the environment and can use various organic molecules as food for themselves and convert them into electrons they release into the environment. The researchers use the microbial electrochemical ultraviolet cell to harness these electrons and use their energy to make chemicals that can degrade the harmful organic pollutants in pharmaceutical wastewater.

The process produces highly-reactive hydrogen peroxide, which is then subjected to ultraviolet radiation to produce active hydroxyl radicals that can degrade complex dissolved organic matter in pharmaceutical wastewater. The radicals are strong oxidants that bind to and mineralise virtually all organic molecules.

The experiment used a two-chamber microbial fuel cell with a working volume of 180 ml. The researchers started the process, and the bacteria in the domestic wastewater generated enough energy to produce hydroxyl radicals, thereby rendering the pharmaceutical wastewater harmless to humans between a few minutes and a few hours. The process removed 100% of the ciprofloxacin, completely decolourised the wastewater and reduced the chemical oxygen demand by 99.1%. The technology also removed virtually all protein- and humic-like substances from decomposed organic material from animals and plants. Ecotoxicity testing with luminescent Vibro feschri bacteria confirmed that the treated water was non-toxic.

“The treated wastewater was not only completely pure but had been purified in a very sustainable process.”

“The treated wastewater was not only completely pure but had been purified in a very sustainable process, with 75% of the energy used coming from wastewater. We hope that the remaining 25% can come from renewable energy sources such as wind or solar energy,” explains Yifeng Zhang.

Creating a spinoff company

Zhang explains that the researchers are not the first to try to develop methods to use bacteria to extract energy from wastewater but are the first to use this energy to treat pharmaceutical wastewater. The discovery has led to the researchers creating a spinoff company collaborating with various industrial partners to market the technology. The intended customers are primarily private companies that commercially treat pharmaceutical wastewater and can probably see the benefits of using less energy and money and being more sustainable.

“Our technology can expand their market, and we have also established a company to treat pharmaceutical wastewater in Denmark. There is considerable potential to do this more cost effectively and sustainably,” says Zhang.

The next step is to scale up the results to 1,000 litres of wastewater.

Source: Kristian Sjøgren/Novo Nordisk Foundation

Photo: iStock