shortened filter runs after cl2 entry point change
shortened filter runs after cl2 entry point change
(OP)
We recently moved our cl2 injection point from the head of our plant, to the top of our filters in order to help our disinfection by-products{tthms and haa5s).This has succesfully lowered our haa5's, but our filter run times have been reduced from 50-60 hours down to 15-20 hours.We have tried adjusting our alum to lime ratio in order to lower the ph,but this has had basically no effect.We also started feeding potassium permanganate at the head od the plant, still no change.Our plant is a 2 mgd, class two, conventional sand filter plant.





RE: shortened filter runs after cl2 entry point change
Unless you provide additinal information on the treatment plant, it is difficult to understand. For example, is this surface water?, is there a clarification?, is the lime for pH adjustment?, what are you trying to ozidize with potassium permanganate?, etc.
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
How long have you left the system to aclimatise to the new dosing arrangements? Some strange things can happen as the various chemistries and bio chemical systems adjust.
RE: shortened filter runs after cl2 entry point change
Was the transition to the shorter filter runs spontaneous or did it occur over a period of time?
From what you are describing, it seems that you are now growing algae in the sedimentation basins and filtering out the algae in the filters. Is it possible to schock chlorinate in the basins?
RE: shortened filter runs after cl2 entry point change
The transition was almost instantaneous, within 4-5 hours, which is our detention time from the head of the plant to the filters.
We have'nt tried "shock chlorination", but certainly plan on investigating it !
RE: shortened filter runs after cl2 entry point change
Your backwash duration should not have changed. One would expect it to be about 7-8 minutes.
Has the effluent turbidity changed?
RE: shortened filter runs after cl2 entry point change
Their filters take about 4-6 hours worth of operation before boiling, but are getting around 20 hours worth of run times. If a filter that has only been in service for a few hours is backwashed there is no bubbles.
Has your settled water trubididty changed since changing the location of the chlorine feed?
ch81pc - what would you anticipate adding the pot.per. before the lime and coagulant do?
If you find a cure please do post, and I'll do the same.
Mike
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
With regards the boiling I have seen this on a small scale when we altered dosing points. We generated much finer particulates which got carried deeper into the bed. After a 2-3 day period of being in service, the back wash would liberate all of the accumulated gases generated by the bugs eating the Particulate BOD.
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
It would seem that you have a build up of particles in the upper region of the filter. This in turn may cause a zone of negative pressure. This is undesirable because the negative pressures may cause air pockets to develop.
Examine your backwash procedures to ensure the backwash is being done properly.
If the backwash procedures are correct, then take a core sample of the media and evaluate the media.
You also may not have enough water head on top of the filter and/or the filter effluent is free draining to the atmosphere.
RE: shortened filter runs after cl2 entry point change
The name looks familiar, you talking about the Glade Ck. plant?
RE: shortened filter runs after cl2 entry point change
RE: shortened filter runs after cl2 entry point change
oxidized.
Water treatment plants should not have anaerobic sludge conditions except for the residual treatment processes.
Overfeeding of KMnO4 may cause excess manganese (insoluble) to pass through the treatment plant. Overfeeding of KMnO4 will be evident since the water will be pink and have brown/black solids. Other than that, the use of potassium permanganate has little impact on other treatment processes at the water treatment facility.
h
RE: shortened filter runs after cl2 entry point change
This has occured at plants removing manganese with chlorine prior to filtration and where the filter media has become coated with manganese oxide.
If the chlorine is stopped, the "greensand" effect is stopped and operational problems begin.
This can cause significant manganese slough off. The manganese will have to be removed with backwashing, filter-to-waste, or other procedure.