Adaptive Clarifier Inlet

    Distributor for Passavant® hydrograv® adapt

    What is the Passavant hydrograv adapt System?

    Passavant hydrograv adapt System is an adaptive inlet structure for clarifiers. The system comprises of: a telescopic adaptive cylinder, flow guiding plates, encasing of existing inlet concrete structure (optional), a drive station and instrumentation and controls. It includes a proprietary control algorithm developed based on model calibration of more than one thousand clarifiers. The system is usually designed based on Computational Fluid Mechanics (CFD) simulations with the customer’s recent operating data taken into account. This ensures that the system is optimally adapted to the individual requirements.

    Limitations of Cast-in-Place Concrete Inlet Structures

    Cast-in-place concrete inlet structures are widely constructed in clarifiers as a conventional clarifier inlet in water resources recovery facilities (WRRFs). Although considered as a durable structure, the cast-in-place concrete inlet is typically designed based on specific hydraulic conditions and properties of activated sludge. The performance of a secondary clarifier in a WRRFs are impacted by multiple variable factors, including mix liquor suspended solids (MLSS) concentrations, sludge volume index, return activated sludge ratio and hydraulic surface loadings. The conventional cast-in-place concrete inlet structure cannot be optimized according to the current loading situations and misses the opportunity to fully utilize the capacity of a clarifier and provide the best achievable performance.


    Passavant hydrograv adapt System provides an adaptive inlet flow guiding plates that are adjustable to different submerging depths controlled by a drive station based on the current hydraulic conditions and properties of activated sludge. A proprietary algorithm is built into drive station that simulates the proper sludge inlet location and directs the submergence of the inlet structure.:

    • Horizontal flow guiding plates ensure that the feed flow direction is correct as it enters the clarifier and minimizes turbulence
    • Under normal/low flow conditions, inlet sludge flow is directed at a proper depth beneath the sludge blanket and fully utilizes the filtration effect of the sludge blanket to achieve superior effluent quality
    • Under peak flow conditions, the inlet sludge flow is directed at a proper depth above the sludge blanket minimizing turbulence of the sludge blanket and fully utilizes the sludge storage capacity of the clarifier

    Performance Benefits

    Achieves lower than 3 mg/L of effluent suspended solids of a secondary clarifier
    Achieves a capacity increase of 25% to 50% of the design capacity of an existing secondary clarifier; in several full-scale installations, Passavant hydrograv adapt System demonstrated a 130% increase in hydraulic capacity under peak flow conditions
    Provides consistent sludge blanket filtration benefit under normal/low flow conditions and removes nitrogen and phosphorus in particular forms
    Available Literature


    Passavant hydrograv adapt System



    Passavant Hydrograv Adapt Reference List



    Advanced Biosolids Treatment



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