Improvements in water treatment have greatly reduced the risk posed by possible Cryptosporidia outbreaks following well published outbreaks around the world in the 1990s and later. As part of these improvements most filters have been fitted with turbidity meters that are great at picking up coagulation failures. In some regions filter banks have also been fitted with Particle Counters as they have proven to be better at picking up the initial stages of filter breakthrough or ‘channeling’ (where the water meter finds a way through the filter media without being filtered).
Using Turbidity Meters AND Particle Counters on the outlet of a filter not only provides an indication when there are more small particles (turbidity) but also when the larger Cryptosporidia size particles are coming through (particle counter).
Improvements in technology now means that a filter bank can be fitted with particle counters for a similar price to turbidity.
Coagulation Failure vs Filter Breakthrough
In most Cryptosporidium outbreaks there has been a failure of both coagulation and filtration. If coagulation fails then un-coagulated particles can pass straight through a filter. A turbidity meter would pick this up and show the operator that there was something wrong.
If, however, the filter starts to pass large, Crypto sized particles, or to break down, or to ‘channel’ (a channel opens in the filter from top to bottom) it is unlikely that this will be picked up by a turbidity meter, but can clearly be seen with a particle counter.
In the past, to install a bank of 8 filters with a particle counter would have meant a capital cost of approximately $45,000 which has been a stumbling block for many. Now Pi has made a multipoint analyzer providing the same functionality for approximately $25,000 taking away much of the price objection.
Particle Counter Vs Turbidity… Which One?
Turbidity Meters are more sensitive to smaller particles which are present if coagulation fails.
Particle Counters are more sensitive to filtration failures.
So which do you need?
You need both.
Why not contact us and see what we may be able to do to help you reduce your risk of a Cryptosporidia outbreak.