The paper deals with the physical properties and chemical composition of rice husk and dust, which are the waste of the Regulus raw rice growing in the Krasnodar Region of the Russian Federation. Rice dust is formed as a result of the discharge upon the receipt of raw rice from vehicles, removal of impurities, sorting by size, during separation of membranes, crushing, grinding, polishing, moving grain along the elevators and conveyors, i.e. during all technological operations production of rice groats. In order to remove dust, the group cyclone and the bag filter-cyclone are installed in the pneumatic conveying systems and suction plants of "Southern Rice Company", LLC. The paper shows the chemical composition of samples of husk, dust retained by the group cyclone, and dust retained by the bag filter-cyclone. Rice husk contains a significant amount of silicon dioxide -14.8%. The dust collected from the group cyclone contains ferrum (109 mg/kg), plumbum (1.1 ± 0.4 mg/kg), and copper (1.2 ± 0.4 mg/kg). The bag filter-cyclone retains finer dust particles. The dust collected in the cyclone is of yellowish-pink color, and the dust, collected from a bag filter-cyclone, is gray. Fine dust, which has passed through the filter, is drier than the dust, segregated in a cyclone, so it is more explosive and easily ignited. Dust can cause the explosion. The dust properties give an indication of the degree of its danger and the ability to form explosive concentrations in air.

Quantitative chemical composition of ash and slag mix generated upon combustion of Donetsk culm is determined. It is established that ash and slag mix of Novocherkassk state district power plant (SDPP) (Rostov region, Russia) after coal combustion has the following composition: iron -2.3%; mineral constituents -75.8%; calcium oxide -20.4%; aluminum oxide -0.0118%; water -1.3022%; manganese oxide -0.18%; copper oxide -0.0043%; plumbum -0.0017%; it is qualified as hazard class IV for environment. Cadmium, mercury, arsenic, selenium, antimony, bismuth are contained in trace amounts < 0.1 mg/kg. In order to reduce dust emissions the cleaning stage I of gas scrubbing facility is equipped with group cyclone comprised of four cyclone units. Medium and coarse particles under the action of centrifugal force are deposited in the cyclone. This promoted decrease in dust load on bag filters, the cleaning stage II. Qualitative chemical composition of ash captured by group cyclone and that of ash captured by bag filter are determined. Cadmium, copper, plumbum, zinc, iron, manganese, and calcium are contained in coarse and fine particles captured by group cyclone and bag filter. Aluminum referred to light metals is completely captured by cyclone. The ash dust in its bulk is of dark gray color. The ash captured by cyclone contains coarse particles of black color and the ash captured bag filter contains fine particles of light colors (gray-yellow color producing silky gloss). This is characteristic for ash dust after combustion of Donetsk culm. The main component of the ash is silicon dioxide, its content in the ash captured by filter reaches 91%. These fine particles create light tone of this ash.

A calcined sorbent from ash and slag waste of thermal power plants was used for water purification from ammonium ions. Experiments were carried out under static conditions at a temperature of 25±2 °С. The concentration of ammonium ions in the solution was measured by the spectrophotometric method according to the established graduation characteristic tested for convergence and correctness. The sorption process was studied at a sorbent dose of 1.0 g per 50 cm3 of the model solution taking the specific pore volume of the sorbent into account. For a solution with an ammonium ion content of 20 mg/dm3, the following modifications were carried out: the frequency of magnetic stirrer rotation was varied from 50 to 500 rpm; the pH of the solution – from 4 to 9; and the time to equilibrium – from 10 to 210 min. The time to equilibrium was 180 min. The effect of initial concentration of ammonium ions (2.0; 5.0; 20; 50 and 100 mg/dm3) in the solution on the adsorption process was studied under optimal sorption parameters. The adsorption equilibrium in the “ammonium ions–calcined sorbent” system was studied for the initial concentration of ammonium ions from 5 to 300 mg/dm3. Experimental data were processed using Langmuir and Freundlich adsorption isotherms. The maximum value of adsorption comprised 1.1251 mg/g. The experimental data were found to agree with the Langmuir theory. To describe the adsorption kinetics, the parameters of pseudo-first and pseudo-second order equations were determined. The highest convergence between the experimental and calculated data was achieved by the pseudo-first order model.

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