Treatment of stormwater to bathing water quality by dissolved air flotation, filtration and ultraviolet disinfection Available to Purchase

For the first time, a process for the treatment of urban stormwater has been designed in order to obtain treated water suitable for bathing activities. The degree of pollution removal is taken as far as the microbiological disinfection of the final effluent. This process, which combines air flotation, filtration and ultraviolet (UV) disinfection, has been tested at the pilot plant level in the eastern suburbs of Paris, France. The removal efficiency obtained on total suspended solids (TSS) and chemical oxygen demand (COD) through the flotation stage is close to 90% or better. The flotation facility has proved to be perfectly adapted to urban stormwater treatment with a maximal efficiency in the first minute of operation and with a TSS residual concentration consistently about 45 mg/L regardless of the variations in polluting loads entering the process. This is essential when taking into consideration the extreme variability of this load during rainfall. Sand filtration with a continuous washing system prevents operational interruptions during rainfall events. The UV disinfection process allows the microbiological contamination of the effluent to be reduced to a level in compliance with the regulations that define the quality of bathing water.