Equalization (EQ) is a means of buffering or equalizing the characteristics of wastewater prior to entering the wastewater treatment system. Industrial waste streams vary considerably in both level of contaminants (pH, total suspended solids, etc.) and flow rates. To minimize the impact of these fluctuations on down stream processes, equalization should be considered. Benefits of EQ include:
- Substantially reduced chemical costs, especially associated with pH fluctuations, and coagulants and flocculants required for solids removal.
- Smaller downstream treatment components. Downstream treatment components do not have to be sized to handle instantaneous flow peaks.
- Ease of operations. EQ substantially reduces process adjustments required in day-to-day operations.
Most EQ systems consist of a tank that is mixed or aerated to keep solids from settling in the EQ tank. Depending on the waste stream, aeration may be required to keep the waste from becoming septic and odorous.
CWS recommends that the equalization system be capable of holding one-day of peak wastewater flow. If the waste stream has large settleable solids, screening may be required prior to the equalization. Also, considerations must be made with regard to the type of coating on the tank, especially if the waste stream is very acidic or caustic.