Volume 10
Issue 2
Civil Engineering
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Available Online: http://www.ejpau.media.pl/volume10/issue2/abs-05.html
THE EXPERIMENTAL VERIFICATION OF RICHARDSON-ZAKI LAW ON EXAMPLE OF SELECTED BEDS USED IN WATER TREATMENT
Tadeusz Siwiec
Department of Civil Engineering and Geodesy,
Water Supply and Sewage Systems Section,
Warsaw Agricultural University, Poland
ABSTRACT
The paper presents and discusses the characteristics of various methods of determining the exponent for Richardson-Zaki [34] formula, which binds the flow velocity of rinsing water, sedimentation of bed grains in water, as well as bed porosity at various states of expansion. The characteristic of methods served for verification of their correlation with the results received from experimental tests, where the exponent was the degree of inclination in the relationship log V = n · log ε + log Vs, which is a logarithmic form of Richardson-Zaki formula. The tests were carried out for 8 minerals such as anthracite, barite, chalcedonite, diatomite, clinoptylolite, nevtraco, sand and pyrolusite. In order to make results more trustworthy, they were carried out for 10 fractions of each bed. It was shown that the formulas, from which the value of exponent n is commonly calculated, give results not differing much from one another, but considerably different from experimental ones, where the exponent was the degree of inclination of the above mentioned function. The results close to experimental ones were given by the formula containing sphericity of particles developed by Dharmajah and Cleasby [5]. Experimental results of testing enabled to develop the exponential functions describing the relationship of exponent n on Reynolds number in the state of free sedimentation.
Key words: backwashing filters, bed expansion, porosity, fluidization.
Tadeusz Siwiec
Department of Civil Engineering and Geodesy,
Water Supply and Sewage Systems Section,
Warsaw Agricultural University, Poland
Nowoursynowska St. 159, 02-776 Warsaw, Poland
Phone: +48 22 59 35 161
email: Tadeusz_Siwiec@sggw.pl
Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.