I think what you're describing above is the Slow Sand Filter not the Rapid Gravity Filter. The slow sand filter is that filter that forms a dirt layer called Schumutdecker that traps and forms a colony of bacteria. Contrary to the slow sand filter, the RGF in a COAGULATION and FLOCCULATION water treatment process filters the carry over Flocs from the Clarifiers, just before Disinfection. The idea is to make sure the water passing out of the RGF has a turbidity less than 5.0 NTU/FTU and that is needed in order to achieve efficient disinfection. The consistent clogging/blockage of the RGF is as a result of those carry over flocs and that can be solved by checking the dosage rate of the Aluminum Sulphate or whatever coagulant they are using perhaps because of changes in the raw water quality seasonally certain changes needed to be done periodically. Another way is to look at the Alkalinity of the raw water if the alkalinity is low and pre-lime is used then secondary precipitation might result in that excess flocs carried over to the filters.

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I think what you're describing above is the Slow Sand Filter not the Rapid Gravity Filter. The slow sand filter is that filter that forms a dirt layer called Schumutdecker that traps and forms a colony of bacteria. Contrary to the slow sand filter, the RGF in a COAGULATION and FLOCCULATION water treatment process filters the carry over Flocs from the Clarifiers, just before Disinfection. The idea is to make sure the water passing out of the RGF has a turbidity less than 5.0 NTU/FTU and that is needed in order to achieve efficient disinfection. The consistent clogging/blockage of the RGF is as a result of those carry over flocs and that can be solved by checking the dosage rate of the Aluminum Sulphate or whatever coagulant they are using perhaps because of changes in the raw water quality seasonally certain changes needed to be done periodically. Another way is to look at the Alkalinity of the raw water if the alkalinity is low and pre-lime is used then secondary precipitation might result in that excess flocs carried over to the filters.