WEF Discussions — Now on LinkedIn!

WEF is pleased to announce the creation of free LinkedIn groups associated with its technical discussion forum topics. Through these LinkedIn groups, members will be able to view and participate in discussions, as well as communicate with one another via direct messages. Share your experiences and knowledge, ask questions and respond to other discussions as frequently as you like!

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Biological Phosphorous Removal - Anaerobic Digestion
James Royer
Posted: Tuesday, May 4, 2010 3:33 PM
Joined: 9/21/2009
Posts: 98

I read an article about the Biosolids Management at the Charlotte-Meckenburg McAlpine Creek WWTP recently. This 64 MGD plant utilizes biological P removal and then anaerobically digests the solids to make a class B biosolid for land application.

Their discharge limit for phosphorous is stated at 1067 lbs/day on a monthy average which would be a 2.0 mg/L P in the effluent. It would appear that their bio P removal is mostly a waste of treatment effort. I do not know what their influent P levels are but even without P removal treatment 40% would be removed just with activated sludge.

I would hope that they are looking into a procedure such as Ostara or some other chemical method to remove the phosphorous from the sludge dewatering centrate so that phosphorous removed during bio P will be kept out of the recycle to the head of the plant. Bio P should result in a discharge of 0.5 mg/L on a routine basis.

I think that Bio P removal and anaerobic digestion should have chemical sequestering of the P in the recycle stream as a requirement. This would help reduce phosphorous entering our waterways.