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UDC 628.356.5

Kevbrina M. V., KOZLOV M. N., Dorofeev A. G.

Secondary settlers: comparison of the calculation methods in designing and analysis of the parameters of efficient operation of the facilities

Summary

The results of the comparison of methods of calculating secondary settlers through the example of a model wastewater treatment plant (domestic method according to SNiP 2.04.03-85, German method according to Germany Standard ATV-DVWK-A131E, American method based on mass flow theory) are presented. It is shown that the surface area of settlers calculated according to Standard ATV has higher values compared to the calculations according to SNiP 2.04.03-85 and American method. The values of the surface area of settling tanks calculated according to SNiP 2.04.03-85 and American method are very close. At the same time the SNiP method is much simpler and requires much less initial parameters than the American method. For the domestic practice of operating secondary settlers it is proposed to introduce a new parameter – «dry matter loading on the settler surface» taken from the mass flow theory. This indicator indicates how much dry matter of the mixed liquor from aeration tanks enters per unit surface of secondary settlers per hour and corresponds to the incoming mass flow. By varying the dry matter loading on the surface of secondary settlers it is possible to provide for the standard suspended solids concentration in effluent. Through the example of the operating 54 m diameter settlers the dependence of the clarification efficiency on this parameter is shown.

Key words

wastewater , biological treatment , sludge index , secondary settling tank , activated sludge , calculation method

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