Chlorination

Introduction and Objectives

Chlorination is the final step in the treatment process. Chlorine disinfects the effluent, killing whatever pathogens may remain. AguaClara plants use a flow control module (FCM) to regulate chlorine dose. The chlorine flow is driven by available head in the FCM and the dose is changed by increasing or decreasing this available head. Chlorine is added in the plant. The residual from this chlorine should guarantee protection from pathogens along the distribution line. In this study, the chlorine residual was measured daily in the storage tank, and three houses along the distribution line. Additionally, samples were taken from the storage tank and the chlorine residual was measured in them over time. The flow rate in the chlorinator was measured to make sure the FCM was delivering the expected dose.

Methods

Chlorine residual was monitored daily in four locations in the distribution system. The tank, the first house in the distribution line, a house in the middle of the line and the last house in the line. Chlorine residual was measured with a Pentair Pool Products™ Pool and Spa Test Kit which used ortotolidine to detect chlorine. However, in should be noted that the test is a fairly subjective colorimetric test and that the measurements were taken by three different people. Therefore the results only show relative levels of chlorine not exact amounts. To measure how long the chlorine residual lasts at different effluent turbidities. Water samples were taken from the storage tank and then the residual was measured.
FCM

Results and Discussion

Monitoring the chlorine residual along the distribution line was a good method of ensuring that that water was safe to drink. The residence time from the plant to the end of the distribution line depends on the demand on the system making it difficult to determine how long the chlorine residual lasts. Furthermore, samples were not taken at the same time each day at each location. More information about chlorine residual was gained from the samples taken from the tank. An effluent sample with turbidity of 26.49 NTU and an initial chlorine residual of 1.5 mg/L had measurable chlorine residual for fifteen and a half hours. At this point the residual was 0.3 mg/L. Effluent samples with less than 4 NTU turbidity and chlorine concentrations of 1.5 mg/L taken on different days contained detectable chlorine for over

FCM Measurements

Conclusions

The chlorine residual should be sufficient. The FCM needs to be kept clean. The hose for the FCM might be too short as well.
seventy-two hours.