WEF Discussion Forums
Operation and Maintenance
Digester Gas Piping
We have digester gas piping flow issues due to reduced ID caused by a buildup of scale in the pipe. This is causing reduced flow to our co-gen engine and making the dome relief valve do its job and open to atmosphere hence the loss of gas.
We've been trying backflushing with water with little effect. Any ideas for a short term "fix" for this problem. I've been trying to access the Kendall Barry article with no luck.
“Removal of Interior Scale from Digester Gas Piping, by Kendall J. Barry © 1965”
OK,,The only way to get that kind of build up in a digester gas line is to have the digester overflow into the line.HAve you tried to have the line cleaned by a highpreassure sewer cleaning truck?
What kind of prerasure are you running at the engines?
We went thru an episote where this happened durinf some foaming events and in the end we replaced some piping to remove the scale buildup.
Dr. Jenkins is adament that foaming in the activated sludge just turns into foam in the anaerobic digester.
Our Piping was glass lined, when the Digester was Dismantled there was no sign of scale anywhere.
Agreed with Dr. Jenkins, in that foaming from the aeration basins
becomes the primary source of foaming in the digesters. As a
manufacturer of foam control additives that actually work on biofoam, we
see most of our digester foaming in the late winter, when higher MLSS
are maintained for successful treatment. Of course, such higher MLSS
means older sludge age, which means more foaming tendencies. When these
late-winter WAS solids are fed to the digesters, foaming is typically
much more likely. ESP's FC REL will counter this problem, and so the foam will not build in the lines.
Glass lined pipe always good idea, pigging lines, jetting lines. ALso victaulic connections to make removing pieces of pipe easier. So in looking at some of the responses nocardia foam in AT is a primary cause of foaming in Digester? Rich
We are going CCTV route to inspect extent of phosphate scaling in digester piping. The piping is insulated. Any experiences/suggestions with CCTV inspection for pressure piping or alternative inspection methods will be helpful.