What is a normal dosing rate for pwtag PAC?

PWTAG recommends a normal dosing rate of 0.1ml/m 3 of the total flow rate, which it has also described as 0.005ml/m 3 as aluminium. There are now a number of different grades of PAC with aluminium concentrations between 9.5% and 18%. The concentration of aluminium is not the only consideration when selecting a grade of PAC to use.

How should Pac be dosed in a peristaltic pump?

PAC should be dosed continuously using a peristaltic pump. All grades of PAC should be dosed at a rate of 0.1ml/m 3 of the total flow rate. PWTAG Technical Note released in February 2014 about polyaluminium chloride (PAC) dosing. Continuous coagulation with PAC is recommended by PWTAG.

How much PAC should pwtag use?

The lower aluminium content products have a higher basicity, so the best advice that PWTAG can give is to use the same dosing rate for all grades of PAC, that is 0.1ml/m3 of the total flow rate. PAC should be dosed as far upstream of the filters as possible, but after the chemical controller’s sample point.

How is polyaluminium chloride dosed?

This was dramatically improved, to over 90%, by dosing polyaluminium chloride. PAC is directly and continuously dosed from the containers in which it is delivered at a rate of about 0.1ml/m 3 of the circulation flow. (It is very important that it is not diluted with water as it will form a gel.)

What is the coagulation removal rate of polyaluminium chloride (PAC)?

Without coagulation removal rates in a single pass of a medium-rate filter were about 50%. This was dramatically improved, to over 90%, by dosing polyaluminium chloride. PAC is directly and continuously dosed from the containers in which it is delivered at a rate of about 0.1ml/m 3 of the circulation flow.

How does polyaluminium chloride coagulation work?

Continuous coagulation with polyaluminium chloride has long been recommended by PWTAG – especially in the light of the threat from Crytposporidium. Like all coagulants PAC works by extracting and then clumping together dissolved, colloidal and suspended matter. The resulting floc is then trapped on the filter.