Biological Processes

SPIRAC > Seletar STP Sludge, Screenings and Grit Conveying Storage


Singapore ConveyorsSetlar STP is situated in the northeastern part of Singapore and handles 114,000 m3/day of sewage flow from an equivalent population of 480,000 persons.

Over 1,000m of SPIRAC shaftless spiral conveyors were installed in 1998, handling sludge, screenings and grit.

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CB&I > Biosolids Profile - ESD Class A System

London, OH

In 2006, the City of London embarked on a major expansion of its' wastewater plant including a new biosolids processing facility to replace existing conventional digesters. The new digestion system was designed as a two phase, Class A system with CB&I's ATP/ESD process.

The Phase 1, thermophilic ATP Reactor acidifies the incoming feed sludge and provides pathogen reduction in a batch feed process in compliance with the USEPA time-temperature requirements. The Phase 2, mesophilic Egg Shaped Digester (ESD), utilizes the volatile acids, generated in the first phase, to further reduce solids and produce methane, completing the solids reduction process.

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Aqua-Aerobic Systems, Inc. > Buxahatchee WWTP

Calera, AL

The Buxahatchee Wastewater Treatment Plant in Calera, Alabama was built in 1960. It upgraded in 1985 to a 0.75 MGD capacity extended aeration system with integrated clarifier and traveling aeration bridge for nitrification. By 2004, the system could no longer handle the flow capacity brought on by community growth, nor the increased stringent nutrient limits set by the Alabama Department of Environmental Management (ADEM). To resolve the plant's issues an upgrade was in order. The CIty of Calera decided to investigate several other treatment technologies, and required a written process performance guarantee. The only company that met the criteria was Aqua-Aerobic Systems with the AquaSBR® sequencing batch reactor (SBR) and AquaDisk® cloth media filters. Not only was Aqua the most cost-effective choice due to the technologies' small footprint, but the new treatment train could also provide advanced nitrogen and phosphorous removal without the use of alum or other chemicals.

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CB&I > Biosolids Profile - ESD Class B System

Spokane, WA

In 2006, the City of Spokane contracted with Garco Construction and CB&I to construct improvements to its' Riverside Park Water Reclamation Facility. The work involved the replacement of a 30 year old concrete anaerobic digester with new steel Egg Shaped Digesters (ESD) and related systems for mixing, heating and process control.

The City evaluated several factors, resulting in selection of steel ESD, including:

  • A need to install more capacity in an extremely limited footprint.
  • Steel ESD provided better safety relative to the failed post-tensioned concrete digester.
  • The vessel is completely gas tight so it minimizes impact on the surrounding neighbors and environment.
  • A faster construction schedule and improved constructability could be realized with steel ESD.

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