New method clears micropollutants from water

Researchers at MIT have developed an electrochemical system to remove very small concentrations of specific pollutants from water.

Everyone can agree that pollutants need to be removed from water, but removing very diluted concentrations of pollutants requires a great deal of energy and the use of high concentrations of chemicals. Now, a method developed at the Massachusetts Institute of Technology (MIT) can remove even very low levels of unwanted contaminates. The method, described in the journal Energy and Environmental Science, in a paper by scientists at MIT and at the Technical University of Darmstadt in Germany, uses an electrochemical process to remove selective contaminants such as pesticides and chemical waste products.

In the new system, water flows between chemically treated surfaces that act as positive and negative electrodes. The amount of charge can be altered or ‘tuned’ to bind strongly with a particular type of pollutant. The researchers found that this process can effectively remove pollutant molecules down to concentrations of a few parts-per-million. The system of using two electrodes eliminates the need for high voltages that can create additional polluting compounds, as well as allowing simultaneous selective removal of both positively and negatively-charged toxic compounds at the same time. Researchers also hope that the process can be used to recover high-value compounds during the chemical production process, lowering waste. According to researcher Xiao Su, “Such systems might ultimately be useful for water purification systems for remote areas in the developing world, where pollution from pesticides, dyes, and other chemicals are often an issue in the water supply. The highly efficient, electrically operated system could run on power from solar panels in rural areas for example.”

The researchers have applied for a patent on the new process and are working on scaling up their prototype devices. Still to come are testing the process under real-world conditions, and for long periods, to check durability. In the future, this system may join other innovations, such as drones that ‘eat’ floating trash and biodegradable fishing nets to help clean rivers and oceans of pollutants. What other innovations might be needed to create clean water for all?