Design of SBR systems for nutrient removal from wastewaters subject to seasonal fluctuations.

Designing SBR systems for simultaneous biological nitrogen and phosphorus removal is evaluated and defined for wastewaters from small coastal areas subject to seasonal fluctuations in quantity and quality. A design procedure is developed using basic process stoichiometry and significant operating parameters. A stepwise approach was utilized to secure full nitrification, available nitrate limitation for denitrification, a mixed phase with enough anaerobic fraction for P removal. A fundamental relationship between the effective sludge age, the recycle ratio and the cycle time was developed and used for the determination of physical design parameters.