THE DESIGN OF DISINFECTION CONTACT TANKS

The basic concept of chemical reaction engineering, as applied to the disinfection of water in a continuous flowing system, is summarized, a nd the effect of flow dispersion (i.e. the spread of residence time) o n the efficiency of the process is highlighted. It is shown that defic iencies compared with the ideal batchwise situation can be offset by a djustments to the residence time or the disinfectant concentration, pr ovided that the design is reasonable. The term 'compensation factor' i s offered as a means of characterizing tanks which are intended for a specific duty. Reference is also made to recently available software w hich now enables tanks to be evaluated at the design stage without res orting to specialist computing services.