In last years, limits of NOx emission are more and more strict. Selective non-catalytic reduction (SNCR) is one of the most used technologies in thermal power plants. The process has also some disadvantages. One of them is contamination of coal combustion fly ash, which is as a secondary energetic products used in many branches. It is the most commonly used for recultivation of coal mines and in the construction industry as an ingredient for  Portland cement production. Unutilized coal combustion fly ash is stored on repositories.  The main problem of SNCR fly ash is the presence of ammonium soluble salts, which could be washing out and ammonia release in an alkaline environment.

In 2017, at Faculty of Chemistry at Brno University of Technology, there was patented the method of fixation ammonium ions presented in a fly ash structure. Patent describes using of organic compounds, tannins, as stabilization agents. Tannins are plant polyphenols with high molecular weight, which occur in wine, berries and wood. Water extraction from wood is relative simple process. When mixing of tannin solution with SNCR fly ash, insoluble compounds are created. They inhibit ammonia wash out and release.

Requirements for waste disposal and natural resources mining are decreased by using of coal combustion fly ash. It is convenient from an economical and ecological point of view. Using of renewable natural material is a low-tech and innovative solution, which enables using of SNCR fly ash, contaminate by ammonium, without adverse impact on the environment.