The original focus of this installation was to reduce the effluent COD and BOD without having to dredge. The BOD and COD were significantly reduced along with the TSS which prevented the mill from closing due to tight effluent restrictions on a small discharge stream during the droughts of 1997, 1998, 2010 and 2011. There has been no dredging since the baffles were installed.
The original 3D sludge survey indicated just over 1.0 million cubic yards of sludge in the lagoon in 1996, a second survey in 1998 showed there was less than 800,000 cubic yards of sludge in the lagoon even though the effluent TSS dropped from 70 mg/l down to 30 after the installation was completed. A third survey in 2003 showed there was less than 750,000. Original testing of the existing sludge showed a very high organic content (>80%) due to the tremendous amount of fiber in the front third of the lagoon from lengthy clarifier outages.
Nine baffles totaling 10,020’ were installed in 1996 and are still in operation today.
The drawing below shows the lengths and layout of each baffle. The aerators were spaced 225’ apart and the baffles were designed to create 225’ channels.
Google Earth image shows the actual layout as it is today.
BOD removal rates were improved from 78% to 90%.
BOD removed/HP/day improved from 9.5 to 25.0.
Contacts: Available on request