Improving the evaluation of filtration robustness

Drinking water filtration systems should be as robust as possible to consistently provide finished water of high quality to protect public health. The quantification of robustness makes it possible to evaluate the status of a given system. This paper introduces a newly developed turbidity robustness index, which differentially weights average performance and deviations from average. A second new robustness evaluation method — the probability method — was also developed. This method provides the basis to implement almost real-time online monitoring of filtration robustness as the filter cycle develops. This may be particularly useful in smaller systems, which usually have less direct operator oversight. Both of the newly developed robustness approaches were applied to assess filtration turbidity performance at selected full-scale water treatment plants.