Published by Ashish Yadav, Assistant Director at Ministry of Defence, India
Hello Everyone,
Suggestions are invited on replacement of sand media with AFM in Rapid Sand filter. We are facing problems of Rapid Sand filter clogging, mud ball formation, and turbid water after filtration.
We already had that problem.
You sould review the back wash flow rate and eventually the back wash parameters.
Published by Márcia Reis, engª
Sounds like your water supply has gotten higher in suspended solids, especially clay particles. Addition of a flocculant like Alum, deeper sand bed layers and more frequent and longer duration backwash possibly at higher pressure should do a better job of suspended solids removal. Do you know if your turbidity after filtration is being caused by suspended solids or dissolved salts/organics?
Published by Robert Duff, UtraPure Water/ Wastewater Engineer at SUNY Polytechnic Institute - CNSE
Dear Ashish,
As I suppose, in both cases you will have the same suspended solids, and maybe you could continue with the same cogging period in both media if both media have the same particle size.
Other gestion could be that you use a multimedia filtration system in which you could use a larger size antracite layer over the sand filter to retain the higher particles over, and the smaller particles down in the sand layer.
Whatever case, it will be good that you do a pilot test with all this technologies before exchance the media.
We can help with an innovative containerized technolgy that can be used to filtrate drinking water repleacing clarifiers and sand filtratio in one equimpent, and in just one container you can filtrate from 20 to 100 l/s, depending the inlet parameters savign area and chemicals.
Regards,
Orlando D. Gutiérrez Coronado
Published by Orlando D. Gutiérrez Coronado
Please check stepwise
Inlet water characteristic changed from the designed one?
System feed pumps are adequately designed or changed recently from previously installed or their VFD are not working
Air release valve on Sand filters are working?
How old is the Sand media and what are the layers you have placed I.e. at least 4 layers of media are there properly
Check the strainers are not loosen due to pressure built up and if these are tightened properly or not.
If media filter vessels are sized properly according to flow rate?
I think one by one you need to look into this aspect and solve the problem.
Also check if the feed water quakltiy is worsen then you may need any coagulation flocculation pipe Flocculator sedimentation prior to sand filters....
Do not jump to simply change this to Carbon Filter.
Published by Engr. Mansoor Ahmed PhD. Scholar, Consultant/Advisor Water/Wastewater Treatment - Consultant
Great suggestion! The plant was designed in 1992 and sand media hasn't been changed since then. 6 Layers of media with gravels and different grading sand is used. Flocculator is also being used prior to sand filters and we are using Alum. But i will also try and check the other things you suggested. Thanks
Published by Ashish Yadav, Assistant Director at Ministry of Defence, India
Please replace your media at all as it has been 25 years of sand media not changed.
Published by Engr. Mansoor Ahmed PhD. Scholar, Consultant/Advisor Water/Wastewater Treatment - Consultant
Increase sand-bed height.
proper pressure & time of air scoring.
Increase backwash water flow rate will be solve your problems.
Published by Brijesh Panchal, Executive at reliance industries limited
AFM is used to removed specific substance, perhaps the substances cause this issue when it adheres to media surface. You also have to look into the backwash flow rate and perform air scrubbing as recovery.
Published by WEI CHOEW LEE, Employee at Organo (Asia) Sdn Bhd
You seem to have backwash issues
Published by Kevin Khan MTO Eng, PO Eng , TTI, Licensed Power Operations Engineer 1st Class , Licensed Technical Instructor ;
It sounds like you need to sort out the backwash system. Sand should work okay if it is washed properly. Amirtharajah's work from 1990s with collapse pulse backwashing is key.
Published by Michael Chipps, Thames Water Utilities Ltd - Principal Research Scientist