Particle counters as tools for managing Cryptosporidium risk in water treatment

Outbreaks of waterborne cryptosporidiosis have been a major concern for the Water Industry in the UK and US over the past ten years. Management of risk from Cryptosporidium in water supplies relies heavily upon operation and control of water treatment processes to maximise oocyst removal. Difficulties in measuring oocyst concentrations in water supplies have led to evaluation of surrogate parameters with which to assess oocyst removal by treatment. Whilst turbidity measurement can give an indication of the risk of oocyst breakthrough from filters, a more sensitive indicator appears to be particle counts in filtered water. The paper gives a demonstration of the potential for particle counting as a tool for managing Cryptosporidium risk, and describe ways in which particle counting can be used for monitoring and controlling water treatment plant operation. With the present level of knowledge, the most suitable application for particle counting is as a diagnostic tool for the identification of operating conditions which reduce or minimise particle counts in filtered water at individual sites.