Wastewater Treatment - Foaming and Denitrification
The Old Forge WWTP generally produces an effluent quality well within permit discharge limits. However in 1997, the plant experienced sporadic problems with high effluent settleable solids. Ted Riehle, the chief operator worked with NYSDEC's Operations Assistance group to try and correct the problem.
The plant operator identified two potential causes for the problem, escaping nocardia foam and denitrification. Since the plant design does not include a chlorine contact tank, any floating solids leaving the clarifier end up in the plant effluent. The operator has no safety factor to polish the secondary effluent.
The plant staff, working with DEC Regional inspectors and Technical assistance staff developed two unique steps to separately handle the foam and denitrification problems:
Nocardia foaming - The chief operator, Ted Riehle, utilized a foam wasting strategy to address the nocardia problem. The plant staff developed a low cost foam collection and pumping system - see figure 1 and 2 below. When a nocardia bloom occurs, the drum is lowered into position, the water spray turned on and the sump pumps the foam to the aerobic digester. Removing the foam provides positive nocardia control without affecting the treatment process.
To address the denitrification problem plant operators, the group developed a method to run the secondary clarifiers in series. The effluent line from clarifier #1 passes through clarifier #2. By valving this line, the plant staff can open the valve and run the clarifiers in series if needed. This provides additional clarification time to treat any denitrification or foaming problems that still occur in clarifier 1. The plant staff did all the work in-house.
As a result of the operator time and effort installing these modifications, the plant effluent has improved significantly, see Table #1 below
Table 1 - Improvements in Effluent Quality
| Time Period | Effluent BOD, mg/l |
Effluent TSS, mg/l |
Effluent Sett. Solids, ml/l |
|---|---|---|---|
| Before Assistance Program | |||
| June 97 - May 99 | 13 | 12 | 0.8 |
| After Assistance Program | |||
| June 99 - May 00 | 9 | 8 | 0.1 |
| Percent Improvement | 31 % | 33 % | 88 % |
For further information regarding these improvements call Ted Riehle at (315) 369-6280 or Tim Miller at (518) 402-8106.
Nocardia Foam Wasting Setup
35 gallon drum in aeration tank.
Hoist provides drum height adjustment.
Sump pump in drum. Concrete
weights covered by liquid.
Foam Waster in action. Foam
flows into drum. Water spray
knocks down foam. Pump
sends foam to aerobic digester
Final Clarifier Changes
New plastic piping installed.
Slide gate allows the operator
to easily switch from series to
parallel operation. Elbow added
to reduce inlet velocity and
minimize short circuiting.
This will serve as the effluent weir.
The lower elevation provides the
needed head difference.
Modified Scum Trough to allow
skimming at the lower elevation.
Clarifier #1 pipe in discharge box.
The installed elbow provides head
difference so flow enters clarifier #2
rather than going out the discharge box.
Contact Ted Riehle, chief operator, at (315) 369-6280 with questions and comments.
