Thickening and Dewatering of Wastewater from a Flue Gas Desulfurization Scrubber Facility
Situation: Wastewater from a forced oxidation FGD scrubber facility was first sent to a thickener and then a vacuum truck was used to remove the wet scrubber sludge to an on-site landfill. This process bypassed a filter drum that the plant was not using because it was not running correctly and the filter cake did not release from the cloth. This process was costing upwards of $300,000 year in removal costs and extra landfill weight fees. In addition, plant engineering was tasked with developing a new sludge dewatering system that was budgeted for at least 1 million dollars. WTS was asked to get the filter drum dewatering system back on line.
Solution: WTS reviewed the plant’s existing filter drum equipment for potential reuse. WTS used PSA (Particle Size Analysis) testing and utilization of filter cloths with different SCFM (Standard Cubic Feet per Minute) ratings and was able to choose the appropriate cloth that allowed the filter cake to dewater and release easily from the drum. WTS added a customized engineered polymer feed system that allowed polymer, a cationic polyacrylmide) to be fed to the thickener only when the underflow clarifiers were being pumped to it. This allowed appropriate doses of polymer to maximize thickener sludge density that further enhanced sludge dewatering from the new filter cloth. The flow rate of this system is 120gpm and the volume of sludge thickened and dewatered is ~13 to 18 tons per 8 hour shift.
Benefits: WTS was able to bring the plant’s filter drum system back into use creating significant cost savings of approximately $300,000/ year.
- The use of a vacuum truck was no longer necessary to suck up the wet scrubber sludge.
- The dewatered sludge cakes are significantly lighter and cost less money to add to the landfill.
- A 1 million dollar capital engineering project was eliminated from the budget.
See below for a video of the filter drum processing scrubber sludge.