Refurb of Slow Sand Filters
Refurb of Slow Sand Filters
(OP)
Anyone have experience of refurbhising slow sand filters? What are the chracteristics of a slow sand filter in good condition- ie. good quality sand (uniformity coefficient), best practice for skimming?
Cheers,
Jim
Cheers,
Jim





RE: Refurb of Slow Sand Filters
RE: Refurb of Slow Sand Filters
For skimming the key is to get the sand depth as uniform as possible, areas with less sand depth or a higher permiabilty (for what ever reason) will obviously take more flow, becoming blind and anearobic long before the rest of the bed which could lead to quality issues.
As mentioned by CCOR, your filter will only be as good as the pre-treated water you are putting on to it (exponential relationship between loading and run time). Is you raw water from a river or a borehole?
I have managed to acheive 0.1m3 (water)/m2 (sand) per hour for well over 18 weeks feeding the filter with water from the Thames pre-treated with pre-chlorination (no Cl residual must reach the SSF's!!), pre-ozonation, rapid filtration (assisted at times of high turbidity with ferric chloride dosing).
Hope this helps.