Ammonia: From a Forgotten Element in Sewage to a Valuable Resource
▲ Department of Environmental Research, KICT
- Adsorbent Material Developed for the Selective Recovery of Ammonia from Sewerage
- Key Technologies Acquired for the Establishment of a Carbon-Neutral Sewerage Treatment Facility
The Korea Institute of Civil Engineering and Building Technology (KICT) has developed an adsorbent material that selectively removes and utilizes ammonia from sewage, which contains a range of pollutants.
The ammonia found in wastewater is a prominent contaminant. If left untreated, it can lead to eutrophication (algal bloom) in rivers and generate foul odors in wastewater treatment plants. It also contributes to soil acidification and is a cause of particulate matter generation, compounding environmental concerns.
Currently, nitrogen compounds in sewage undergo a process of conversion to ammonia, followed by nitrification and denitrification in wastewater treatment facilities. However, this treatment process poses challenges, as it requires substantial energy and resources. As of 2019, the electricity consumption in domestic wastewater treatment facilities reached 3,650 GWh. This accounts for only 0.7% of the total electricity supply in Korea (520,499 GWh), and yet approximately 30% of this energy is utilized for the removal of nitrogen compounds such as ammonia from the water.
Ammonia is a valuable resource used to produce fertilizers and aqueous urea solutions, and also is utilized in a range of industrial activities. While its production continues to increase, Korea still relies fully on imports for its industrial ammonia. As well, the conventional production method of the energy-intensive Haber-Bosch process under high temperature and pressure further contributes to energy consumption. What if we could recover and reuse ammonia, instead of simply removing it? This approach could dramatically reduce the energy consumption involved in wastewater treatment and ammonia production, ultimately leading to a reduction in carbon emissions.
Research on ammonia recovery from sewage is being conducted globally. However, due to the odor issue caused by ammonia leakage during the recovery process and the technical limitations of the developed materials, finding commercially viable technologies has been challenging.
To address this, the research team from the KICT’s Department of Environmental Research, led by Dr. Kang Sung-won, has achieved a breakthrough in the development of an ammonia adsorbent material that offers simple production processes and enables mass production. Previously, the selective adsorption of ammonia using Copper hexacyanoferrate (CuHCF), a nano-material, had limitations in terms of its practical applicability in wastewater treatment due to difficulties in recovery. The adsorbent developed by Dr. Kang's research team chemically combines CuHCF with ion exchange resin, featuring particles measuring 1-2 mm, which are suitable for wastewater treatment.
In addition, this adsorbent shows remarkable ammonia selectivity even under conditions with a range of coexisting contaminants, surpassing the efficiency of other adsorbents. The adsorbed ammonia can be easily separated from wastewater through a simple regeneration process, enabling the recovery of a highly-concentrated ammonia solution.
The developed technology is expected to significantly contribute to achieving carbon neutrality by dramatically reducing the greenhouse gases emitted during the ammonia treatment process.
This achievement was developed with the support of the Ministry of Science and ICT, as part of the Research on Next Generation Environmental Technology for Carbon Neutrality project (2021 to 2022). The findings have been published in the February issue of the Chemical Engineering Journal, a leading international journal in the field of environmental engineering.
