Every year, thousands of cases of river and lake pollution are recorded in Russia, a significant part of which is associated with industrial and urban wastewater. One of the key problems is the high content of ammonium nitrogen, which provokes water bloom and the death of ecosystems. Scientists from Perm Polytechnic University have developed a method that not only purifies wastewater, but also extracts a valuable fertilizer from it — struvite.
Struvite is a mineral consisting of magnesium, ammonium, and phosphates. In nature, it is found in the form of crystals, and in industry it is used as an effective fertilizer and additive for animals. However, its extraction from wastewater has remained a difficult task: crystals form unevenly, which reduces the efficiency of the process.
The researchers conducted a series of experiments, studying the effect of acidity (pH), temperature, and mixing speed on the formation of struvite.
Optimal conditions:
- pH 8-9;
- High temperature;
- Mixing speed — 300 revolutions per minute;
To extract high-quality struvite, it is important to maintain the acidity of the water and consider the mixing speed of the components. Experiments with solutions under different conditions revealed that crystals grow faster at high temperatures and a water acidity value of about 8-9 pH. The faster the mixing rate, the smaller the particles. We have established an optimal speed – 300 revolutions per minute. It allowed us to obtain large and uniform crystals of about 10 micrometers, which are suitable for filtering and treating wastewater.
An experiment conducted by scientists also revealed that the addition of silicon-containing substances made it possible to obtain smaller and more uniform crystals (about 10 micrometers), which simplifies their filtration. The technology increases the efficiency of wastewater treatment up to 98%, while simultaneously producing a useful fertilizer. This solution can be implemented:
- At wastewater treatment plants in cities;
- In livestock complexes;
- At industrial enterprises that discharge nitrogen-containing wastewater;
The study was conducted as part of the "Priority 2030" program, and its results are published in the materials of the international conference "Chemistry. Ecology. Urbanistics."
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