OPTIMIZATION OF CSO STORAGE AND TREATMENT SYSTEMS

Combined-sewer overflow (CSO) must be controlled by a storage-treatmen t system because storm flow in the combined sewerage system is intermi ttent and highly variable in both pollutant concentration and flow rat e. A treatment facility operating without the benefit of upstream stor age would need to be very large and costly in order to handle the rela tively high volume and flowrate of a CSO. Similarly, if storage is use d without treatment, the storage volume required would be very large a nd also expensive. This paper describes a strategy to optimize CSO con trol system. This optimized system maximizes the use of the existing s ystem before new construction and sizes the storage volume in concert with the wastewater treatment plant capacity to obtain the lowest-cost storage and treatment system.