The article compares linear hydraulic losses calculated from Colebrook-White, Prandtl-Karman and Blasius formulas with the measured on a test pressure in pipelines with the diameter of 63, 75 and 90 mm, made of PVC and PE. The pipelines were arranged in loops through which flew sewage with the suspension contents of about 460mg/dm3. As a result of the tests it was established that the accuracy of the Colebrook-White formula is higher than that of Prandtl-Karman and Blasius formulas (the only exception being the diameter of PVC63). However, it does not reflect properly the character of changes of linear pressure losses that accompany the increase of the speed. This character is better reflected by formulas for hydraulically smooth pipes, particularly by the Prandtl-Karman formula. Differences between values measured and calculated for the tested scope of diameters and speeds do not exceed 10%. In most cases, however, the calculated values are smaller than the measured ones.
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The paper presents the problem of crystallization of hydrated magnesium ammonium phosphate (struvite), a chemical formula MgNH4PO4 ∙ 6H2O often formed in the line of wastewater treatment plant sludge. Struvite crystallization tests were performed on a laboratory scale, assuming three independent variables which were pH, concentration of phosphate ions PO43- and the concentration of ammonium ion NH4+. The size of a search was required concentration of magnesium ions Mg2+, which occurs when struvite precipitation. It was found that the crystallization of struvite occurs in a wide range of concentrations of phosphate and ammonium ions, but most depend on the reaction. In the analyzed conditions, struvite is not precipitated at pH 7.0 from 7.5 and precipitated an increasing range of concentrations of individual components.
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To designing of the pressure sewage systems, built of pipes PE and PVC, essential are hydraulic calculations, which would consider physical properties of sewage. In the applying norm [PN-EN 1671 2001], missing right formulae which would consider these properties. In connection with it, in this article, remained introduced methodology and results of experimental researches, which was a pur-pose, determine empirical relation for calculate linear losses coefficients in pipes PE and PVC, during the pressure flow sewages. Showed that the flow of sewage had character in pipes of PVC and PE of flow in pipes hydraulic smooth, and linear losses coefficients s determined from experimental research in pipes of PVC and PE is taking comparable value, which in the range for the recommended speed v are bigger to value sBlasius calculated from the Blasiusa formula.
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