Filtration CCP

Dear all,

I have a question about our developping-HACCP plan.

Our drinking water treatment plant is equipped with the folllow steps:

1) Spring source (by-the-way, is a karst spring, r

1.1) Raw water turbidity measurement (minimum 0.17 fnu, max 30 fnu during 2012)

2) Flocculation step (it works only by a turbidity greater than 0.30 fnu measured at the point #3.1)

3) Rapid sand filtration

3.1) Turbidity measurement

4) Ozonation

4.1) Residual ozone concentration measurement

5) Activated carbon filtration

5.1) Turbidity measurement

6) Chloration (NaClO) for distribution network protection

6.1) Reservoir tanks

7) Residual Chlorine measurement

8) Distribution network

Now, we have identified our CCP as the final chloration step (measured at the point #7).

The question is:

I am analyzing arguments to decide if the turbidity measurement @ the point 5.1 can be a CCP for the effectiveness of the global filtration process / (included the flocculation step) ..... or must be simply a control point?

Our statistical values are showing that during 2012 the maximum value of turbidity leaving our plant was 0.12 fnu, with a mediane value of 0.06 fnu, and never we had problems with biological growth.

Any thoughts on this ?

Your opinion ?

Thank you,

Joe

Joe,

I would pose this question to you, why would you consider step 5.1 turbidity as a CCP? What hazard is present and could turbidity harm or cause illness.

I would said turbidlity is a quality control point.

From your listed steps, CCP of your system, would be ozonation and chlorination. The CP would be your various filtration steps

I can ask why Ozonation is a CCp for you?

Ozonation products can be an health problems?

Turbidity: you is right! After the filtration step we have a desinfection to kill bacteria associated to solid particles.

Ozonation is a control/kill step for bacteria. if your ozone concentration level is too low, bacteria can survive and possible contaminated product.

the same applies to chlorination, too low of a concentration will result with the same issue,

Also too high of a concentation for both, can it can be a health hazard for the consumer.

It looks like this HACCP isn't for a bottle water product.

Water sources usually contain natural organic matter. Concentrations are measured as dissolved organic carbon and can vary. Organic matter creates problems such as odor and taste and can also create problems such as organic disinfection by products formation. To produce pure drinking water, the removal of this organic matter is important.

Ozone seldom achieves a complete removal of organic matter.  Combined with a subsequent filter and coagulant is usually the best approach. The removal of organic matter is required to reduce the development of disinfection byproducts which are mainly formed during the reaction between organic material and a disinfectant e.g. chlorine. The reaction of chlorine with organic matter can lead to the formation of byproducts such as trihalomethanes (THM).

While ozone is considered a better biocide thank chlorine in terms of immediate effect, ozone rapidly decomposes in water, its life-span in aqueous solutions is very short (less than one hour). This can make it difficult to confirm disinfection of the water at a later stage.

So, both Ozonation and Chorlination can be considered CCP’s. Operationally Chlorination is probably the key one. However you need to consider whether THM is a significant hazard and therefore the controls in place to deal with this e.g. ozonation and filtration need to be CCP’s? Do some research, and conduct a risk assessment.

George

Thank you for both opinions.

The HACCP is not for bottled water. We produce drinking water for network distribution.

Two remarks:

i) For CCP's, the experts said is to choose only the last step for desinfection (step 7, free chlorine measurement). For step 4.1 (ozone measurement), it will be a double as "desinfection-step" check, so it can act as a "Control Point" or "PRPo".

ii) We don't have possibilities to monitor on-line the THM's formation (we need a gas-chromatograph on-line), so I cann't consider ozonation and filtration as CCP's. But a normal CP or PRPo.

Remarks?

Thank you,

Joe

Dear Joe,

Similarly to George, I suggest some people (ie other "experts") might ask whether the chlorination step will achieve the required microbiological effect for the specific hazard in the event of no ozonation.

If the answer is yes, i rather agree with you, otherwise i doubt that it is a single step CCP in a traditional haccp presentation sense (ie no OPRPs are available :smile: ).

Rgds / Charles.C

That's correct.

If ozonation go down, chlorination must ensure the correct desinfection log's for microbiology is ensured.

In this point of view, this step is a CCP.

Joe,

Here another potential hazard you may want to review as part of your HACCP process. Like George mention, there is a high chance of THM formation especially in the process you described. TTHMs will form from the oxidation reaction between the ozone and chlorine. Also bromide will convert to bromate in presence of ozone. You'll have to research what are the acceptable levels of these compounds in die Schweiz 

You are correct SPL,

but levels are very low for both TTHM and Bromide.

Absolute no problems.

Thank you.