Wastewater Treatment

Wastewater Treatment

Preload wastewater tanks are reliable, efficient, and cost-effective

Since 1930, Preload has provided municipalities and private industry with the highest quality, most dependable wastewater and process tanks. Not only is a Preload wire-wound prestressed concrete tank a superior containment structure, it’s a good value because it requires negligible maintenance throughout its long life.

With their proven reliability, efficiency, and long-term cost savings, Preload wire-wound prestressed concrete tanks deliver the ideal wastewater CSO/SSO/EQ storage, wastewater treatment, and wastewater reuse storage solutions.

You can choose from a wide range of styles and sizes. Our tanks can be built at grade or partially buried, incorporate a clear-span dome roof or designed as an open top. They can accommodate almost any floor configuration or wall connection to accommodate equipment commonly associated with wastewater treatment processes.

Wet Weather Storage

Communities continue to grapple with severely aging conveyance infrastructure and undersized combined sewer systems. Peak flow from wet weather events and infiltration create sanitary sewer overflows (SSO’s) These SSO’s are environmentally harmful and problematic with state and federal regulatory agencies.

Combined sewer overflow (CSO) and sanitary sewer overflow (SSO) reduction projects utilize PRELOAD tanks as a cost-effective solution to mitigate overflows by equalizing wet weather inflow while protecting streams and waterways.

  • PRELOAD tanks can be constructed above or below ground, conforming to the project’s hydraulic requirements.
  • Open top or covered PRELOAD tanks can be constructed depending on configuration and odor control needs.
  • PRELOAD wet weather tank configurations and optional equipment include:
    • Conical Floors
    • Odor Control Systems
    • Wash-down Systems
    • Architectural Features
    • Mixing Systems

Reuse and Reclaimed Water

Water reuse: Recycling is not just for bottles, papers, and cans

Reclaimed water reuse has become a common feature at wastewater treatment plants, especially in regions where water is at a premium due to arid conditions or depleted aquifers. PRELOAD tanks reliably store water reclaimed after the treatment process until it is distributed to businesses, homeowners and the agricultural industry for irrigation, cooling and industrial processes.

Recycling treated water reduces both wastewater treatment plant effluent and potable water consumption for high demand water uses such as irrigation. Additionally, injecting reclaimed water back into the ground can replenish depleted aquifers.

Primary and Secondary Clarification

Primary and secondary clarifiers are the backbone of most wastewater treatment plants and remove vast amounts of solids from the influent flow. The proven reliability and durability of prestressed concrete tanks make them ideal for this application. The watertightness characteristics of PRELOAD tanks eliminate leakage and unsightly cracking which is characteristic of convention cast-in-place concrete tanks.

PRELOAD clarifier tanks include various types of effluent launders with connections for weir plates, internal or external drop boxes, conical floors and solids collection sumps. A center pier foundation can be designed to support any manufacturer’s mechanism or treatment equipment.

Sequencing Batch Reactors

PRELOAD tanks are uniquely suited for sequencing batch reactors. Our tanks include excellent hydraulic mixing characteristics, floor designs for diffuser installation and geometrically true, smooth wall caps for bridge mounted diffusers.

Numerous options are available for installation of air piping, below floor or through wall influent/effluent piping, weirs and aerators.


PRELOAD digesters can be designed for both aerobic and anaerobic process applications. Our concrete dome roof is well suited to provide a reliable gas tight cover without interior columns which interfere with mixing and process.

Additionally, the geometry of PRELOAD’s dome and wall shell provides the most efficient design for resistance of internal pressure. Our tanks can be constructed using chemical resistant concrete, an interior coating or interior high-density polyethylene (HDPE) liner, depending on the nature of the process. Gas collection piping or covers can be designed to recover methane created by the digestion process.

Prestressed concrete aerobic digesters typically do not require a roof so open top prestressed concrete tanks provide an excellent tank option for this process. Prestressed concrete tanks are watertight and do not weep or produce unsightly cracking like conventional cast-in-place concrete tanks. Additionally, since the concrete is in a permanent state of compression, prestressed concrete tanks are much more robust.

Influent Equalization Storage

As part of our wastewater solutions, PRELOAD has designed and constructed equalization storage tanks that can be sized for normal plant influent flow and surge flow during wet weather events.

We offer a broad array of capacity options and custom design features, including:

  • Elevated perimeter concrete walkways
  • External access stairs
  • Internal mechanical mixers
  • Tank wash down systems
  • Sloped floors with sump pumps
  • Odor control sleeves

Package Plants

Circular prestressed concrete Package Plant tanks provide excellent value and versatility. These tanks commonly include multiple chambers within and outer ring and center tank. Various treatment processes occur in each chamber such as equalization, clarification, aeration, digestion and thickening. Together these chambers provide a full wastewater treatment process contained in single tank thereby simplifying and minimizing the treatment process footprint.

PRELOAD tanks can be customized to incorporate a wide variety of manufacture’s process equipment, piping and configurations. Our can engineers work closely with your designers and process equipment suppliers to integrate the treatment system for project success.

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