Problems with cold weather

[CivilEngineer401]

I am working on a small municipal wastewater treatment plant (50,000 gpd) which is primarily fed by a low pressure sewer system. We have an activated sludge process and the problem we are having is the influent gets too cold in the winter for nitrification (our plant is in northeast Pennsylvania). Originally we thought that we were losing too much heat at the plant but after some field verification, we believe the issue is the sewage influent. We recorded the sewage entering the plant between 1 and 5 degrees Celsius at the worst part of winter. What we believe is happening is that all of the heat is being lost while the sewage sits within the individual onlot grinder pumps.

The only thing I can think of to solve our problem is to heat the influent before it enters with plant with some form of steam injection system or to add another process to the plant with biomedia which has a thermal mass and can provide extra protection for the bugs. Does anyone have any other suggestions?

 

[bimr]

It will not be economical to heat the wastewater. A fixed film process is the best option.

http://www.nelsonenvironmental.com/sagr/default.asp

http://www.iwaponline.com/wst/03312/wst033120155.htm

http://www.gov.mb.ca/conservation/eal/registries/4864wpgww/cow_nitstudy/presect-04.pdf