GAC over Sand filter design for 60mgd plant
GAC over Sand filter design for 60mgd plant
(OP)
I am having problems designing GAC over sand filter for a 60mgd plant. Do you have any suggestions determining the depth of sand, and any idea for the EBCT for GAC, influent turbidity is around 120 NTU to the system, and it is conventional water treatment plant with, flash mixing, flocc. and sed.
thanks
thanks





RE: GAC over Sand filter design for 60mgd plant
As far as sand depth, I have used 12" of sand for both shallow and deep bed filters (18" through 60" anthacite or GAC).
The EBCT for the GAC depends the purpose for the GAC. GAC in high rate filters is typically good for biofiltration when ozonating and removal of some taste and odor compounds because of the low EBCT (2 to 7 minutes). If you are trying remove TOC, then you may need as much as 10 to 20 min EBCT. To get these high EBCTs you may want to condider seperate carbon contactors after filtration. You really need to pilot to select the correct type of GAC (lignite, bituminous, coconut shell...) and EBCT for your water source and your desired finished water quality. I have found GAC to cost 50% to 100% more than anthracite. You may want to put GAC in one filter as a trial to see how it works.
I hope this helps. You may want to look for additional papers on this topic in the conference proceedings from the Water Quality and Technology Conference and Annual Conference of the AWWA.
RE: GAC over Sand filter design for 60mgd plant
RE: GAC over Sand filter design for 60mgd plant
It depends on the geographical location of the plant. In Asia and the Middle East, 60 USGPD per person per day is sufficient. While in the US and Europe, design of WTP based on 100-150 USGPD per person per day are very common.
Hope this helps.
Ver