Immediate Free Chlorine Correction for Fluctuating Flow & Changes in Water Quality
Over the years, chlorine disinfection has played a critical role in protecting drinking water supplies from infectious diseases. Currently there are three main methods of dosing chlorine into a water source (i) Manual dosing with adjustments based on sampling (ii) Chlorine dosing based on water flow ratio, and (iii) Online free chlorine measurement and using a closed control loop to adjust the dosing of chlorine. Each of these methods has limitations and is prone to dosing additional or insufficient amount of disinfectant.
The most inconsistent chlorine dosing method is to take manual samples and adjust the pumps accordingly. This system does not allow for immediate correction to the changes in flow rate or water quality. The accuracy depends on the intervals of the sample and human error.
Dosing using chlorine to water ratio is set this is certainly an improvement. With this system the changes in the flow rate will have an instant effect on the disinfectant dosing. However if the water quality changes, this can result in not being able to maintain the desired residual chlorine levels.
Using a free chlorine online sensor combined with a close loop controller is one of the better methods to maintain a preferred dead band. One of the shortcomings of the online free chlorine measurement technologies is the response time, which can range between 120 seconds to 5 minutes. During this period it is possible for a reasonable amount of untreated water to be dispensed.
Due to the gap in the industry, Burkert has developed an online chlorine sensor based on an electrochemical measurement principle with an industry leading response time of 30 seconds. This sensor is used on a system which also takes the flow measurement into consideration. The 8619 multiCELL uses multiple logic blocs to immediately increase or decrease chlorine dosing based on changes to the flow rate and a true free chlorine measurement based on a closed PID loop.
Regardless of changes to the water quality or flow fluctuations, an intelligent system like this will help kill pathogens, control biological growth, destroy hydrogen sulphide, remove ammonia, control odour and improve drinking water taste while using the correct amount of chlorine, regardless of changes to the water quality or flow fluctuations.