What is a flow equalization tank?
Waste water and sewage treatment company generally provide flow equalization tank at all small-scale installations to normalize the flow over a twenty-four (24) hour period. (Note: Larger facilities designed on the basis of both average day and maximum day flows will not be required to provide flow equalization unless otherwise needed for a specific unit operation/process.) Pumps shall normalize flow through the use of timers and not floats. Float controls for pump activation shall only be utilized for high and low water alarm events or to prevent overflow conditions.
Were shall the flow equalization tank be located waste water and sewage treatment company?
The flow equalization tank shall be located after the primary settling tank(s) and prior to all other treatment processes, however some waste water and sewage treatment company at any independent location subjected it has good pumping system for downstream treatment.
What should be the Capacity of flow equalization tank?
The flow equalization tank shall have an adequate effective liquid capacity to accommodate variations in the influent flow rate when the effluent is pumped (or gravity flow is controlled) at a constant rate equal to the average design flow for the facility. For treatment plants serving residential developments with design flows of less than 40,000 gallons per day (151 m3 /d) the waste water and sewage treatment company provides flow equalization tank shall have a minimum effective liquid capacity of fifty (50) percent of the design flow. For treatment plants serving residential developments with design flows between 40,000 and 100,000 gallons per day (151 – 379 m3 /d) the flow equalization tank shall have a minimum effective liquid capacity of thirty-three (33) percent of the design flow. For treatment plants serving residential developments with design flows greater than 100,000 gallons per day (379 m3 /d) the flow equalization tank shall have a minimum effective liquid capacity of twenty-five (25) percent of the design flow. Smaller or larger capacity flow equalization tanks may be warranted for nonresidential uses depending on the expected variations in sewage flow rates.
What are the construction and other requirements of Flow equalization tank?
The flow equalization tank shall be watertight and shall be constructed of reinforced concrete. The tank and covers shall be designed and constructed so as to withstand an H-20-wheel load. Any tank installed in a location by a waste water and sewage treatment company where there is high ground water shall be weighted to prevent the tank from floating when emptied. Buoyancy calculations shall be included on the design plans for any tank with any portion installed below the anticipated high ground water elevation.
Base – The flow equalization tanks shall be installed on a level stable base that will not settle.
Material – The flow equalization tank may be constructed of poured reinforced concrete or precast reinforced concrete.
Access Manholes – The flow equalization tank shall be provided with at least two 24- inch (61 cm) diameter manholes (over inlet and tank center) with metal frames and covers at finished grade. Additionally, a double leaf, hinged pump access frame and lid at grade, large enough to accommodate the removal of pumps without entering the tank, shall be provided by the waste water and sewage treatment company over the flow equalization pumps. Distance between access manholes shall not exceed fifteen feet (4.57 m) on center.
Accessibility – The flow equalization tank shall be located so as to be accessible for servicing and cleaning.
Backfill – Backfill around the flow equalization tank shall be placed in such a manner as to prevent damage to the tank and piping.
Groundwater – The invert elevation of the inlet and outlet and any joint of the flow equalization tank shall be at least one foot (0.3m) above the maximum ground water elevation.
Pumps – The flow equalization tank shall be equipped with at least two (2) submersible sewage pumps. Pumps shall be non-clog or grinder type. The design criteria for pump removal, level controls, alarms, valves, electrical, motor control, pump motor, and power cords, shall be the same as those listed under sewage pump stations. Centrifugal suction lift pumps may be used by waste water and sewage treatment company provided a separate dry well is provided or the pumps are located within the treatment plant building. Air lift pumps are also acceptable. Gravity flow through the equalization tank should be considered where the hydraulics permit.
