PAC Slurry Dosing Suytems

[Hasanf]

thread164-41936
Hi I need some basic design information on PAC slurry dosing systems, capable of achieving 30-50mg/l for pesticide removal as part of a drinking water treatment process stream.
What does the system comprise of - ie bulk PAC storage tank, day tank, pumps?
How is PAC to be dosed - eg concentrations in the day tank, carrier water requirements, wetting and mixing of PAC etc

kind regards

 

[bimr]

A slurry tank is desirable. You can pump directly out of the slurry tank with a metering pump. The slurry tank is based on 1 lb carbon/gal of water and is mixed. Allow 20% extra capacity.

On smaller systems, feed control is achieved by regulating the flow of dry carbon through a dry feeder equipped with a slurry pot.

Carbon slurry piping systems are designed to provide approximately 1 gal/lb of carbon. Velocities 3.5 to 5 ft/sec are best.

 

[ashtree]

You probably should think about a pipe and pump flushing system that swings over to clean water for a few minutes before shutdown. You dont mention how big your system is but small metering pumps, under about 20 litres per hour may have problems because of the passages are a bit small through the pump. If you are really careful and flush the pump everytime you may get away with it.
Talk to your metering pump supplier but they usually have stainless steel bodies.
Dust can be an issue when you are batching up the slurry.
I assume you have done the labwork on the pesticide removal because some pesticides like atrazine are not removed very effectively with PAC.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"