More Floc

Question: Steve, in your March 2003 “Increased Floc” article, you responded to a reader’s question regarding increasing amount of floc in the wastewater pretreatment clarifier even though “nothing in our operations or chemistries has changed...” Chances are that something did indeed change, and detective work is needed to find the culprit.

Question:

Steve, in your March 2003 “Increased Floc” article, you responded to a reader’s question regarding increasing amount of floc in the wastewater pretreatment clarifier even though “nothing in our operations or chemistries has changed...” Chances are that something did indeed change, and detective work is needed to find the culprit. Let me tell you about an experience several years ago. Just like S.T., we were seeing higher solids in our clarifier, sometimes causing non-compliance. Of course, initially the process line and wastewater operators responded, “nothing has changed.”

We did not accept these responses at face value. After much detective work, we found the culprit, excessive dosage of anionic polymer. Due to equipment failure, the anionic polymer was continuing to be fed into the system even when no wastewater was being fed to the system. Once this was corrected and the polymer dosage returned to its target value, the amount of floc and metals in the clarifier’s effluent dropped back to historical levels. D.E.

Answer:

Thanks D.E. This is another example that with many wastewater pretreatment chemistries “more is NOT necessarily better,” in fact, “more is bad.” I am sure your experience will help others.

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