New Technology: New Method To Purify Wastewater And Produce Ammonia Simultaneously

In a paper published in the new issue of Nature · Catalysis, scientists reported an electrochemical method that can convert wastewater containing nitrate into ammonia and purified water.

Ammonia is one of the chemicals with the largest production in the world, and its global annual demand as fertilizer and other substances reaches 180 million tons. Because its production process depends on high temperature and high pressure conditions and uses hydrogen as raw material, ammonia production contributes 1.4% of global CO2 emissions every year and consumes 2% of global energy. At the same time, nitrate loss in agricultural and industrial production may pollute water resources.

After mixing the ammonia solution produced by the existing electrochemical device with the supporting electrolyte (salt), it must be concentrated to a high concentration, and then separated to obtain ammonia products. The team of Rice University in the United States has designed a three chamber electrochemical device that can convert wastewater into ammonia and purified water. The waste water is added into the device and flows through the porous solid electrolyte layer to convert the nitrate solution into water and ammonia. Nitrate pollutants are removed from water, and ammonia gas is generated at the same time, without further purification. This process is very effective, and purified water and ammonia gas can be generated at the common nitrate concentration of industrial wastewater, i.e. 2000ppm (1ppm is one millionth), without additional supporting electrolyte.

The research team concluded that this kind of device can realize a more environmentally friendly ammonia production mode, and is also conducive to wastewater treatment. However, they also mentioned that these results are based on laboratory settings, and future research needs to evaluate the applicability of this device in practical applications.