Greetings;

I'm trying to improve operations at our sites industrial WWTP and hoping to find some of the answers on this forum.

We have 3 clarifiers that, for some reason, have been modified from their original design.  The outlet from the scum box has been blocked so that all floatables eventually fill the the box.  Once full, an operator climbs onto the clarifier and the box is scooped out manually into a bucket, then disposed of into a dumpster.  

If I'm not mistaken, the floatables would normally run into a collection box, then evetually return to the head of the plant.  Is the collection box a place where manually cleaning can take place?

Is there a flushing system that is incorporated to help move the "scum" along.  Can modifications be made to this part of the system to improve the handling of the "scum."

The clarifiers are 40 years old and may need some upgrading.

Thanks in advance,

redeady

Has the scum box been blocked accidentially or on purpose?

All;

To Tom's question first.  Yes, the outlet was intentionally blocked.  Apparently the system never worked well and this was the procedure (although a poor one) that was established.

So the outlet was plugged intentionally as a result of "it" constantly plugging "itself."

I must point out that this practice was discontinued after sharing details with our she manager.

It's time to find a better solution!

On to Jeff's reply.  Our wastes are from the manufacture of pharma and food products.  They are the residuals from meat, soy, casein, wheat and corn products.

Some of our products produce the amino acid tyrisine which generally stays solubilized in our products, but some turns granular and makes it way to the WWTP.  It doesn't break down and, of course, it floats.  We also use use a filter aid (perlite) that will occassionally float and not break down.  

These two items mix with floating sludge, slime and algae to form the "goo" that deposits into the scum box.

I'm just wondering if others have had similar problems and how they solved the plugging issues through modifications and upgrades.

Commisioning Guy.  We our WWTP has only one set of claifiers that follow extended aeration tanks.  I'm not sure if that makes a difference or not.

Thanks,
redeady

All - more specifically Jeff N.

Nope, we have no primary clarifiers.  Plant wastes run to an equalization tank which primarily balances out caustic and acid additions for equipment cleaning, then proceeds to 3 - 210000 gallon
aeration tanks before entering the clarifiers.

Our system is (original) 40 years old and obviously needs re-evaluating and upgrading.

In many ways we are starting over.  Our parent company is lookig to aggressively expand business which will result in more waste down the pipe.  The problem is, we already haul excessive waste off site for processing and what we do waste, we do so with a 40 year old vaccuum filter.  We are lucky to get 10% solids.

I'm getting off topic, which was the clarifier issue.  I focused on that due to the safety concerns.

Any other thoughts on equipment and operations are appreciated.  Maybe I'll start a new "starting over" topic in the near future.

redeady





Do you mean that there is no type of "primary" clarifier, or DAF before the aeration tank(s)?  And, this scum is from the "final" clarifiers?  And, this for a food/pharma plant?  If so, it sounds like you need a whole re-thinking of the system.

I see not only here these scum boxes make trouble an so client does.
I would advice that the pipe diameters of these sum boxes must be minumum 150 mm for proper removal. If the diameter is not big enough this scum clogs the entire pipe till self-cleaning pipe so it does not work.
I have exprienced another solution, there is small basin located on the upper scrapper with a submersible pump that can be controlled by operator on the  bridge with a low-high cotroller. Operator lowers the basin and start the pump and pump sucks the foam. this is parctical but needs extra costs.