Technology that generates electricity through the process of cleaning organic waste has been found to kill pathogens too.
In 2011 a team of researchers at the University of the West of England (UWE Bristol) announced the viability of urine as a fuel for microbial fuel cells (MFCs). The same process, in which wastewater flows through a series of cells filled with electroactive microbes, can now be used to destroy Salmonella.
According to UWE Bristol, the MFC technology could one day be used in the developing world in areas lacking sanitation and installed in homes in the developed world to help clean waste before it flows into the municipal sewerage network, reducing the burden on water companies to treat effluent.
Lead researcher Prof Ioannis Ieropoulos said it was necessary to establish the technology could tackle pathogens in order for it to be considered for use in the developing world.
The findings of the research have been published in PLOS ONE. Prof Ieropoulos, director of the Bristol BioEnergy Centre, based in the Bristol Robotics Laboratory at UWE Bristol, said it was the first time globally it had been reported that pathogens could be destroyed using this method.
“We were really excited with the results – it shows we have a stable biological system in which we can treat waste, generate electricity and stop harmful organisms making it through to the sewerage network,” he said in a statement.
It had already been established that the MFC technology created by Dr Ieropoulos’ team could successfully clean organic waste, including urine, to the extent that it could be safely released into the environment. Through the same process, enough electricity is generated to charge a mobile phone.
In the system, being developed with funding from the Bill & Melinda Gates Foundation, the organic content of the urine is consumed by microbes inside the fuel cells, breaking it down and creating energy.
For the pathogen experiment, Salmonella enteritidis was added to urine flowing through the system, then checked at the end of the process to identify if bacteria numbers had been reduced. Results are said to have revealed that pathogen numbers had dropped significantly, beyond minimum requirements used by the sanitation sector.
Other pathogens, including viruses, are now being tested and there are plans for experiments which will establish if the MFC system can eliminate pathogens entirely.
John Greenman, Emeritus Professor of Microbiology, said: “The wonderful outcome in this study was that tests showed a reduction in the number of pathogens beyond the minimum expectations in the sanitation world.
“We have reduced the number of pathogenic organisms significantly but we haven’t shown we can bring them down to zero – we will continue the work to test if we can completely eliminate them.”
Prof Ieropoulos said his system could be beneficial to the wastewater industry because MFC systems fitted in homes could result in wastewater being cleaner when it reaches the sewerage system.
“Water companies are under pressure to improve treatment and produce cleaner and cleaner water at the end of the process,” he said. “This means costs are rising, energy consumption levels are high and powerful chemicals are being used.”