The past few weeks, I’ve enjoyed the opportunity to work with some skilled, dedicated wastewater personnel: Suffield, Connecticut’s Bernie Gooch and Craig O’Neil; East Hampton, Connecticut’s Scott Clayton; and Warwick, Rhode Island’s Joel Burke.
Both the Suffield and East Hampton municipal wastewater treatment plants are on their way to compliance with their 5-6 mg/L total-nitrogen limits. Warwick’s Joel Burke is facing a more complicated task, but he too is ratcheting down the discharge. A future blog entry will provide an update on Joel’s successes. Today, I’d like to share the successes being enjoyed by Suffield (2.03 MGD design flow) and East Hampton (3.8 MGD design flow).
Here’s the irony: both Suffield and East Hampton are realizing improved effluent quality by using less equipment. Better treatment at less cost; what a concept!
The situations are similar: nitrification in extended aeration tanks and denitrification in pre-anoxic tanks. Suffield utilizes oxidation ditches, East Hampton plug-flow extended aeration.
At both plants, the anoxic tank retention time has been doubled by dialing down the rate of internal recycle. Doing so has made both anoxic tanks somewhat anaerobic. So say the DO and ORP meters. The nose can’t tell. This is nice: the anaerobic conditions provide enhanced phosphorus removal. Suffield is seeing total-P numbers of less than 0.5 mg/L.
The nitrogen discharge from Suffield has been cut in half; East Hampton’s not quite. Yet. Both facilities anticipate meeting their nitrogen discharge limits for the first time in years. And, since Connecticut has a nitrogen “trading” program, both municipalities are on track to cut their nitrogen credit purchases by more than a thousand dollars monthly.
Thanks for reading.
Grant