What is Equalization tank for Primary treatment in STP?
Flow equalization is the act of reducing fluctuations in flow rate across a segment of a system by providing storage to keep water when it arrives too quickly and supplying extra water when it arrives less quickly than intended.
Because the pace at which wastewater enters the treatment process might fluctuate substantially during the day, it's a good idea to equalize the flow before feeding it to the various treatment processes. In either scenario, the technical challenge is determining the size of the equalization basin necessary to allow the treatment operations to run at a constant, average flow.
The equalization tank receives sewage from the bar screen chamber as well as the oil, grease, and grit trap. In STPs, the equalization tank is the first collection tank. Its primary role is to act as a buffer, collecting entering raw sewage at varying rates and passing it on to the remainder of the STP at a constant (average) flow rate. Sewage flows at a high pace during peak hours. The sewage is stored in the equalization tank and released during non-peak times when there is no or little incoming sewage.
Considerations of the design
The incoming sewer pipe is normally gravity-fed and is located below ground level at a significant depth. As a result, it is advised not to create STP tanks excessively deep, as this would need very deep excavations and costly construction. It also makes the cleaning and maintenance activities extremely dangerous. Compressed air must be forced into the sewage housed in the tank.
This is required for two reasons:
1: It keeps the raw sewage aerated, which prevents septicity and reduces odour creation.
2: It maintains sediments in suspension and prevents solids from settling in the tank, eliminating the need for manual tank cleaning.
The tank can be of any shape as long as it allows for the installation of air diffusers to give full floor coverage and consistent mixing throughout the whole floor surface. The diffusers should be able to be retrieved: For routine maintenance, individual diffusers (or sets of diffusers) may be pulled out and cleaned. This will minimize the number of times the Equalization tank needs to be stopped down for manual cleaning.
Maintenance and operation of the equalization tank
· Always have the air mixing on.
· Ensure that the air flow/mixing is consistent across the tank's floor. Adjust the diffuser positioning as well as the required air flow rate.
· Before the projected peak load hours, keep the equalization tank in wastewater treatment virtually empty (otherwise it will over flow).
· At regular intervals, inspect and clear blocked diffusers.
· At least once a year, manually evacuate settled mulch/sediments.
Why are Equalization Tanks used?
· To bring the temperature of the Equalization tank down.
· For the purpose of uniform mixing.
· To provide the best HCl dose for neutralization.
· To boost bacterial growth in the FBBR.
· To minimize the system's insoluble BOD and COD.
· To avoid solids cloaking in the air distribution system.
· In the wastewater treatment process, to increase the air volume in the equalization tank.
· Due to anaerobic reaction, the odour in the Equalization tank has to be removed.
· To improve the biological system's efficiency.
· In an EC system, to minimize current and electrode usage.
What can Netsol Water offer?
Netsol is a proud manufacturer of WWTPs, WTPs and the related equipment’s. We strive to provide our customers the best value for their investment. We understand that customer satisfaction is the most important thing when it comes to the installation of wastewater or water treatment units that is why we provide expert solutions for your queries.