how to eliminate floating floc during wwt
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Industrial Water Management Technologies, Services and Solutions:
Tech Beullletin: How to Eliminate Flotating Floc During Chemical Treatment of Wastewater
www.chemalliance.us864.201.5418
Floating floc can be a nagging problem when running an industrial WWT system. The floc contains the contaminants being dropped out of the wastewater stream during treatment. If these get flushed through the clarifier and are not settled or filtered out before discharge you may be over your discharge limits.There are many things that cause floating floc. Some of the more notable ones are:1. Water flow too high2. Oxidants such as peroxide in the waste stream3. Floc too light and large for flow rate being used4. Polymer over dose5. Biological outgassing
Oxidants in the Waste StreamAn oxidant, such as hydrogen Peroxide (H2O2) can and will cause floc to float. A way to isolate this is run a jar test. If no floc is observed floating right away, wait. Sometimes it can take as long as 15 – 30 minutes to observe the floc floating (see below)
Water Flow Too HighTurn the flow down. You may be at the limits of flow which the clarifier was designed for so the floc doesn’t have time to settle. If you normally treat at this flow rate investigate other causes.
Industrial Water Management Technologies, Services and Solutions:
www.chemalliance.us864.201.5418
Water can be treated by adding a reducing agent such as bisulfate or a proprietary metal precipitant. Consult your WWT services vendor as to the best procedure for adding these to your waste stream.
Tech Bulletin: How to Eliminate Flotating Floc During Chemical Treatment of Wastewater (cont’d)
Floc too Light and LargeSometimes when treating water a large fluffy floc results. Fixes for this include considering a heavier coagulant, changing to a more compatible polymer or altering how polymer is dosed. A polymer dosing method change can be as simple as altering dose rate or changing polymer concentration being used (perhaps, if it is an emulsion or dry polymer, it is being dosed at 0.3% by volume, try 0.15% by volume). Another option to consider is changing where it is dosed. Sometimes dosing in last reaction tank as well as clarifier can prevent floating floc.
Polymer OverdoseOverdosing polymer leads to floating and suspended floc that will not settle out. These flocs are very small and light and called pin-floc. Jar testing can solve this issue by optimizing polymer dose rate
Industrial Water Management Technologies, Services and Solutions:
www.chemalliance.us864.201.5418
Biological OutgassingAs anaerobic bacteria grow they will outgas oxygen. Large chunks of sediment floating in the clarifier when the system isn’t running and bubbles rising to the surface are signs of biological activity. The clarifier can be treated with a compatible biocide after flushing with an air sparger to retard flora and fauna growth.
Tech Bulletin: How to Eliminate Flotating Floc During Chemical Treatment of Wastewater (cont’d s’more)
There are many causes of floc floating when performing industrial wastewater treatment. Most can be solved by jar testing and observation. Consultation with your wastewater treatment services partner, such as ChemAlliance, will aid in a rapid solution to this problem and help avoid any NOVs (Notice of Violations). Contact us on web at www.ChemAlliance.us or email to [email protected].