Cold Water Coagulation

[Zetaman]

I'm interested in discussing the experiences of people involved in using Alum as a coagulant in low temperature climates. A plant I look after suffers badly in the winter months and should 'ideally' have additional flocculation time added..but that's another story. I'd like to use a Polyaluminium chloride but cost is not on my side.

cheers.Chris

 

[Pump2005]

I use alum at my plant in our coagulation process. This is the first year we've ran in the cold weather months since i've been an operator. I get a real disturbing of the tank with the colder weather. I would also like to here some discussions on this.

 

[dicksewerrat]

Call the City of Minneapolis Water Dept. they operate a lot during cold weather. They get thier raw water from the Mississippi River.

http://WWW.ci.minneapolis.mn.us

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Zetaman]

Thanks for Replying chaps. I've tried getting hold of the WTW but no joy yet.

What I find is that the treatment works needs additional flocculation time when the water temperature drops below about 6 (celcius) but this is currently not available. Literature reviews (backed up by my own jar testing) shows that increasing the pH set point at these times is beneficial. We normally operate at 6.2 but I've suggested a rise to at least 6.8. This worked in the jar test but was mixed on the plant (probably because some Operators didn't buy into the changes and reset things before allowing the changes a chance).

Also the plant only uses alum and jar tests with a Polyaluminium chloride have produced significantly better turbidities. Again cost implications are standing in the way of this suggestion.

Interested to here anyone else's experiences.


cheers....Chris