I'm in good old England! So it can get cold in Winter.
The sewage is domestic waste.
Concrete tanks.
Tanks are in the ground (the top is pretty much level with the ground).
Sludge concentration is about 3% dry solids.
The sludge temp is above ambient as the secondary digester tanks recieve...
Thanks for the reply,
The setup we use is that everything gets fed into the primary digester: primary settled sludge, surplus activated sludge from the aeration lanes and any sludge imports. The secondary digesters were added to reduce pathogen levels in the sludge and the sludge is literally...
Thanks for the help guys. I've had a go at this and I think I've got a reasonable answer for the heat transfered to the tank and lost at the surface. You've also given me enough so I know what I'm looking for now.
I think the best I can hope for is to get an idea of where the major heat losses...
I have a very basic understanding of heat transfer, so forgive my ignorance! I've been looking at the arrangement of secondary digesters on a sewage works I visit occasionally and would like to understand what is going on a bit better. Secondary digesters are basically holding tanks that are...