MODELING OF THE PROCESS OF BIOLOGICAL PURIFICATION IN AEROTANK-DISPLACER WITH BIOCENOSIS, FIXED ON CYLINDRICAL ELEMENTS
Abstract
Biological purification is an important element in the technology of processing household waste water. At many biological purification stations aerotanks are used. At relatively low concentrations of organic pollution, aerotanks-displacer are used. An analysis of existing methods of intensifying the work of aerotanks showed that the application of fixed biocenose is promising. The location of the immobilized biocenose is assumed to be on elements of various shapes. The fixed biocenose has the best extraction ability. The concentration of the fixed biocenose is much greater than the concentration of active sludge.
A two-level mathematical model of biological purification in aerotanks-displacers with fixed biocenosis is improved. Elements with an fixed biocenosis of cylindrical shape are considered. The model takes into account the degree of oxygen supply on the process.The mathematical model is based on the equations of transport along the length of the aerotank of the concentration organic pollution and also the equation of transport of organic pollution and the oxygen over the thickness of the biofilm. These equations are written in a cylindrical coordinate system. The rate of oxidation of organic pollution and oxygen consumption by a suspended and fixed biocenosis is described by the Mono equation. The system of equations is solved by the method of finite differences. The results of theoretical studies of the influence of the oxygen regime, and also the location and distribution of elements with an fixed biocenosis on the purification efficiency are presented.
The efficiency of using cylindrical and rectangular elements is compared. The advantages of cylindrical elements are explained. When using cylindrical elements, their arrangement along the length of the aerotank has less influence in comparison with elements of a rectangular shape. The distribution of the concentration of organic pollution and the concentration of oxygen in the thickness of the biofilm using elements of cylindrical and rectangular shape was studied. The contribution of the concentration of organic pollution and the concentration of oxygen on the oxidation process in biofilm is estimated, and their limiting effect is estimated. When using cylindrical elements, the limiting effect of the oxygen regime decreases. When using cylindrical elements, the volume of biofilm decreases, more complete oxygenation is performed, and the process of oxidation of organic pollution is greatly intensified.
Keywords: wastewater, aerotank-displacer, cylindrical elements, fixed biocenosis, organic pollution, mathematical model
References
Література
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References
Von Sperling, M., (2007). Biological wastewater treatment series. Vol 5: Activated sludge and aerobic biofilm reactors. London: IWA Publishing, 328.
Gebara, F. (1999). Activated sludge biofilm waste water treatment system. Wat. Res., 13(1), 230-238.
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Liao, Q., Tian, X., Chen, R., Zhu, X. (2007). Mathematical model for gas liquid two-phase flow and biodegradation of a low concentration volatile organic compound (VOC) in a trickling biofilter. Internal. J. of Heat and Mass Transfer, 1–13.
Wanner, O., Ebert, N.I., Rittman, B.E. (2006). Matematical modeling of biofilms. Scientificand Technical report, 18, 208.
Kolpakova, О. (2015). Theoretical studies and calculations of wastewater treatment in trickling biofilters MOTROL. Commission of motorization and energetics in agriculture: Polish Academy of sciences, Lublin-Rzeszow, 17(8), 165-173.
Oleynik, A., Airapetian, Т. (2017) Оxygen regime in re-search on the work of plugflow aeration tanks with fixed bio-masses. Eastern-European Journal of Enterprise Technologies, 4/10 (88), 4-12.
Airapetian, Т. (2017) Determination of rational parameters of aerotanks- displacers with fixed biocenosis and taking into account the oxygen regime. Problems of water supply, sewerage and hydraulic. Kyiv, KNUCA, 28, 12-18.
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