A statistical model of pressure drop increase with deposition in granular filters

Abstract

As deposits accumulate in a granular filter, pressure drop across the filter bed required to maintain a constant fluid flow rate may increase. Two pressure drop increase patterns had been observed. In slow sand filters pressure drop remains unchanged for a certain period of time then increases exponentially with the volume of filtrate; in granular aerosol filters pressure drop increases linearly with the amount of deposits from the beginning of the filtration process. New concepts of homogeneous and heterogeneous depositions were introduced in this paper. A statistical model based on these new concepts was developed. This non-linear model was able to reproduce both observed pressure drop increase patterns, including the linear one. Excellent agreements between the present model and experimental measurements were obtained. It was concluded that the two pressure drop increase patterns were indeed caused by different deposit distributions rather than different pressure drop increase mechanisms.

Comparative Study and Evaluation of Sediment Deposition and Migration Characteristics of New Sustainable Filter Media in Micro-Irrigation Sand Filters

“…The quartz sand filter column showed the best hydraulic performance and a more stable flow rate in the filtration cycle compared with the other two materials; the glass bead filter column showed the greatest fluctuation in flow rate, the greatest decrease in filtration rate, and the most unstable flow field. The speed at which the pressure rises in the filter column directly affects the head loss during the filtration period [34], and the pressure variation is another key indicator for evaluating the hydraulic performance of filtration [35][36][37]. A two-factor (type and particle size) variance analysis were conducted for filtration pressure, and it was found that both type and particle size had significant influence on pressure variation.…”

A simulation study of surface water purifying through a polystyrene foam filter

“…The problems of research [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] on water filtration can be divided into several directions.…”

Experimental study of dust deposition in dynamic granular filters

“… 14 Hence, the structure of the granular bed and dust cake formation and growth play important roles in the filtration performances of granular beds. Much research work has been done in this area on granular filters, including that by Rodon and Lee, 15 Otoom, 16 Chen and Hsiau, 17 Qin and Pletcher, 18 etc. Various filter structures and flow patterns of granular material have been proposed.…”

“…Choi 22 concluded that the dust cake was compressed by former cake layers with drag forces of later-formed dust layers, which was based on the dust build up model proposed by Schmidt. 23 Moreover, Qin and Pletcher 18 proposed that two increasing patterns of pressure drop were caused by different deposit distributions, termed homogeneous and heterogeneous depositions, rather than different increasing mechanisms of pressure drop. Although much work has been carried out in this field, in-depth understanding of the mechanism of cake formation/growth and design principles of granular filters is still missing, which is essential to the collection efficiency, filter system resistance and further industrialization of moving granular filters.…”