Case Study 1

WTS provided the manpower, equipment, tools, materials and supervision required to receive and process Flue Gas Desulfurization sludge, lime, and fly ash to produce a processed material for landfill placement.  This facility was part of a 450MW power generating station that was one of the first units to install advanced pollution control equipment known as a Flue Gas Desulfurization. (FGD)

Key Project Highlights: 

  • Orchestrated the maintenance of the centrifuge through the OEM (original equipment manufacturer) and obtaining a warranty on this maintenance.
  • Responsible for removal and processing of the existing sludge material.
  • Obtained all necessary permits and licenses required to comply with all regulatory codes, criteria, and standards.
  • Provided all technical support as part of continued monitoring and support effort aimed at achieving process optimization at the facility.

Cost Savings:  WTS ran this facility with half as many employees and half of the cost of the incumbent contractor.   Our management plan included 1 plant manager, 2 supervisors, and 2 full-time operators/maintenance personnel.  Cost savings were also realized in turning the maintenance budget over to the plant.  WTS also improved the sludge dewatering process to save $150,000/year.

WTS took over management of the process from there and was hired to make all of the decisions on how and when to process the scrubber waste water to produce a final product that would be ready for landfill or other.

The thickener solids were managed and pumped as necessary to be processed.  This consisted of first pumping the solids to a surge tank where a large mixer was used to maintain the slurry in suspension.  All pumping equipment, automatic valves, manual valves, gear boxes, motors, and mixers were WTS’s responsibility to maintain.  From the surge tank the solids were pumped to 1 of 2 centrifuge systems where the slurry was dewatered.  The centrifuges were each at one million dollar pieces of equipment that WTS was responsible for operating and maintaining.  The water was returned to the thickener while the solids were combined with fly ash and lime to create poz-o-tec material.  This material was either sent to a landfill or could be used as a base for secondary roads (beneficial use product) if needed.

WTS was responsible for maintaining all the equipment that was used to feed and measure the fly ash and lime to make the material.  This included lime and fly ash silos, blowers, rotary feeders, slide gates, screw conveyors, belt conveyors, soft start electrical controls, variable frequency drives, PLCs, flowmeters, pH meters, electric pneumatic valves, motorized pinch valves, scrapers, plant air scroll compressor, air dryer, dodge torque arms, dust collectors, sump pumps, and a large pug-mill mixer.  The final product was conveyed to a concrete pad via a conveyor and radial stacker.  The material was loaded onto trucks 23 tons at a time with a front end loader and taken to the landfill for disposal or sent to DOT/State/Township for beneficial use.

Case Study 2

WTS First Defense will provided a 1-meter BDP sludge press system to process the sludge out of the equalization basin.  Samples taken from the basin on the day of the walkthrough were analyzed and revealed a TSS level of 3400ppm.  This means the basin contains 0.34% solids mixed in with the water.

Basin Volume

Basin sides were measured to be about 108’ on each length with a slope angle assumed to be about 30 degrees.  Based on this information a calculation can be performed to determine the volume. The basin volume can be calculated by calculating the volume of a truncated pyramid.  Which is based on the length of sides at the base, truncate, and height.  Basin volume was calculated to be approximately 622,592 gallons.

Blowdown from Clarifiers

Once the volume was known an approximate blowdown volume could be calculated.  During a 3-day testing period the blowdown from the plant was sent to the equalization basin.  Level in the basin increased to 50% during this time.  This equated to about 311,296 gallons or about 72gpm of continuous flow.

Solids Removal in Sludge Press

The BDP press will be utilized to remove solids from the equalization basin. A pump will recirc the basin to stir the solids and a second pump will take suction and transfer to the press.

The 3DP has an independent gravity and pressure zones. This allows optimizing the porosity of the belt in gravity and pressure sections allowing thickening of low solids (<0.5%) in the gravity zone.  In addition, speed for the gravity and pressure zones are independent. This allows adjustments to be made separate maximizing filtrate removal.  This press will allow us to produce the driest cake possible given the low solids in the basin.

  1. Feed Distributor
  2. Independent gravity zone
  3. Entry to pressure zone
  4. Independent pressure zone
  5. Perforated roll increases dewatering
  6. Tubular steel designed for years of use
  7. Discharge area (at top) onto conveyor and into roll-off box