Challenge

Glatfelter is a Wisconsin company which prides itself on its commitment to safeguarding the environment. It spends millions every year to reduce the effects of the papermaking facility on its surroundings and tries to minimize its use of fresh water by reusing process wastewaters whenever possible.

In a plant which processes more than 4.0 million gal/day of wastewater through its primary clarifier, Glatfelter was beginning to experience problems with its biological treatment system, resulting in substandard wastewater effluent. Also, frequent disturbances in the system were causing production to be halted, resulting in lost revenue.

Solution

The solution to this problem was to retrofit Glatfelter’s existing treatment plant with a Folded Flow DAF separator from Siemens Water Technologies. This system is especially suited for pulp and paper applications due to its high hydraulic loading capacity and its effluent quality in fiber recovery applications.

Economics:

• Provides 95% recovery of solids.
• Processes twice the flow of existing DAF savealls.
• Hydraulic design more than doubles the tanks plug flow character, allowing for great variations in flow and loading.
• Small footprint maintains good energy efficiency and float solids concentrations.

Design:

• Hydraulic current travels laterally →
• Heavier clean water peels away from the bottom of the mixture and flows downward →
• Separator ‘folds’ the flow by removing effluent from the same end of the tank where the influent is introduced.

Results

Glatfelter now produces a level of solids discharged from their effluent that is lower than that in Lake Winnebago, the water body the provides the process water intake.

• Despite processing over 4.0 mgd, the separator produces effluent with solids concentration of only a few ppm.
• Typical TSS removal is between 90-95%.
• The separator has treated influent with TSS concentration of greater than 2,500 ppm and processed more than 4,500 gpm.
• The installation provides substantially increased hydraulic throughput without taking up additional floor space.
• It is low maintenance and recovers quickly from overloading with high levels of solids.
• It is completely automatic and self-cleaning.