Wastewater Treatment Plant
Graves Engineering, Inc. provided engineering design and bid phase services and is currently providing construction administration and resident engineering services for Phase 2A Capital improvements at the Hooksett Wastewater Treatment Plant. The plant is being converted from a conventional activated sludge plant to a tertiary treatment facility utilizing an Integrated Fixed Film Activated Sludge (IFAS) process for BOD and ammonia nitrogen (NH3-N) removal in combination with Biological Nutrient Removal (BNR) utilizing a variation of the Bardonpho® process for bio P removal and denitrification.
The IFAS process utilizes high density polyethylene media (Biofilm chips). Each chip has an effective surface area for biofilm growth of 365.8 ft2/ft3. Added to the existing aeration tanks, the biofilm chips create an equivalent of 80 acres of surface area, making it possible to expand plant capacity from 1.1 MGD to 2.2 MGD without constructing additional aeration tanks.
Other improvements include:
• Aerated grit chamber
• Rapid mix chambers
• Flocculation chambers
• Ferric Chloride (chemical P removal)
• Polymer (coagulation)
• Sludge transfer pumps
• 2.0 meter belt press
• Polymer Batching (sludge conditioning)
• Serpentine sludge conveyor
• Converting two abandoned secondary clarifiers to sludge holding tanks
• SCADA system.
Project Summary
Project Highlights:
➢ First treatment plant in the United States to utilize the high surface area Biofilm Chip™ -M media.
➢ Biofilm Chip™-M media made it possible to expand plant capacity without the need to construct additional aeration tanks, which saved the Hooksett Sewer Commission over a $1.0 million.
➢ Obtained a waiver of the American Recovery and Reinvestment Act “Buy American” requirements for the foreign made Biofilm Chip™ -M media.
Project: Phase 2A Capital Improvements
Client: Hooksett Sewer Commission
Project Cost: $4.9 million
Project Status: Substantial Completion April 2011