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by Riverina Water County Council Joined 01-01-0001 12:00 AM Posts 25

Hi All, My chemistry is a bit sketchy so please excuse my poor desciption of our issue... I'm currently investigating the continued blocking of our hypo dosing (PE) lines post carrier/process water. A white substance is accumulating immediately after the addition carrier/process water which I think is a carbonate based (????) compound, as the carrier/process water is treated potable bore water. We don't experience this issue at our other WTPs where we directly inject hypo into the injection point, and unfortunately I can't consider this at the WTP in question due to chemcial dosing response times with respect to plant flows. Any advice here would be appreciated. Jason Ip, Riverina Water jip@rwcc.nsw.gov.au / 0269220658

by patrick.duiveman@midcoast.nsw.gov.au Joined 24-06-2021 05:38 PM Posts 2

G'day Jason. The high pH of sodium hypochlorite is likely causing scaling due to the precipitation of calcium out of the carrier water. Bore water can be very hard (high calcium carbonate) and the addition of hypo causes calcium to come out of solution. There are a few options to deal with the issue - increasing the flow of carrier water, heating the carrier water, using an alternate carrier water, switching to chlorine gas, flushing the line intermittenly with acid (flushing the line pre and post dosing to re-dissolve scaling), dosing hypo direct into the dosing point, treating the carrier water with a small amount of acid to balance the pH... and more. Happy to discuss further if you want to give me a call. Patrick Duiveman, MidCoast Council, Patrick.duiveman@midcoast.nsw.gov.au / 0279557377