03760nas a2200445 4500 20260817173433.0 011298s1985 th r 000| 0eng d .b10151849 AIT Thesis no.EV-85-28 Yossarin Bhimsakka Comparison of declining rate coarse media filtration with constant rate dual media filtration at Bangkhen water treatment plant Bangkok : Asian Institute of Technology, 1985 115 p. Thesis ; no. EV-85-28 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development Thesis (M.Sc.) - Asian Institute of Technology, 1985 Bangkhen Water Treatment Plant used dual media filter to remove the suspended solids from the effluent of solid-contact clarifier. The dual media filters used contains 80 cm of anthracite (E.S. = 0.85 mm; U = 1.5) over 40 cm of sand (E.S. + 0.5 mm, U = 1.5) at a filtration rate of 13.75 m3/m2.h. In this study the possibility of using narrowly graded sand as sole filter medium was investigated. The two sand sizes studied (1.00 to 1.19 mm; 1.19 to 1.41 mm and 1.20 m depth) indicated that the narrowly graded coarse medium produces comparable filter quality while leading to less headloss development. In this case the headloss was found to be more uniformly distributed especially when high filtration rates (>15 m3/m2.h) were used. The backwash velocity computation made for single coarse medium and dual media filters indicated that the former required much higher backwash rate than the latter for comparable degree of expansion. The declining rate filter experiments conducted with single medium filters indicated that the headloss development is lesser in the case of declining rate filtration compared to constant rate filtration for the same water production. This indicates the declining rate filtration can be operated for a longer time before backwashing which will reduce the significantly the operating cost of filter. The headloss equation H/Ho = 1+KO is found to be valid for constant rate filters and the value of K decreased with the increase in filtration rate and increase in sand size. The prediction of headloss for declining rate filters was satisfactory when using the K value of the average (both arithmetic and geometric means) velocity. Water treatment plants Thailand Bangkok Filters and filtration Vigneswaran, S., Chairperson Samorn Muttamara, Examination Committee Lohani, B.N., Examination Committee Federal Republic of Germany (CDG), Scholarship Donor Asian Institute of Technology. Thesis ; no. EV-85-28 Full-Text http://203.159.5.9/ait-thesis/detail.php?q=B20027 .b10151849 mnait x 240411 2 951012 m a x 0 000:001:PDF:b1015184:004658:0:0:0:0:0:0 Abstract n mnait mnait mnarc 22 40 20 Barcode : 30050120804330 CREATED : 2014-05-28 RECORD # : i12804307 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050120224190 CREATED : 2016-09-05 RECORD # : i12972800 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050121073778 CREATED : 2023-10-04 RECORD # : i13442612 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 19896 19896 0 0 0 0 MAIN MAIN mnait 2026-08-17 50.00 0 AIT Thesis no.EV-85-28 30050120804330 2026-08-17 17:34:33 3 2026-08-17 22 0 0 0 0 MAIN MAIN mnarc 2026-08-17 0 AIT Thesis no.EV-85-28 30050120224190 2026-08-17 17:34:33 2026-08-17 40 0 0 0 0 MAIN MAIN mnait 2026-08-17 50.00 0 AIT Thesis no.EV-85-28 30050121073778 2026-08-17 17:34:33 1 2026-08-17 20