P7.1.2.4 Use a control method FAC. FAC Replace that links dose control concentration is dose Low chlorine to FAC residual at more than 50% controller demand2 appropriate location. of its MAV. with more coupled with suitable unit. poor chlorine dose control. Manual monitoring and manual chlorine control when quality is variable. 2 Chlorine demand is the difference between the amount of chlorine to the water and the FAC residual remaining after the chlorine has reacted with other substances in the water. If the chlorine demand of the water increases without an increase in the dose, too little disinfectant will remain to disinfect the water properly. 3 The concentrations of disinfection by-products formed, and therefore the risk they present, will depend on the amount of natural organic matter in the water. Preventive measures Checking preventive measures Corrective Causes action What to check Signs that action is needed Event: TOO MUCH FREE AVAILABLE CHLORINE cont’d P7.1.2.5 Check that a FAC. FAC Determine satisfactory FAC level concentration is the cause of Chlorine dose Chlorine level is produced when a more than 50% the high solution in chlorine new chlorine of its MAV. chlorine strength too dosing container is brought high. solution. Chlorine levels into use. and rectify. in dosing solution too Provide high. training in the preparation of chlorine solutions (including P7.1.2.6 Train staff in handling FAC. FAC Identify the and labelling of concentration is reasons for Spillage of Chlorine level chemicals. more than 50% the spillage chlorine in chlorine of its MAV. and rectify if compound or dosing possible. solution into solution. Chlorine levels dosing in dosing solution. solution too high.
P7.1.2.4 Low chlorine demand2 coupled with poor chlorine dose control. Use a control method that links dose control to FAC residual at appropriate location. FAC. FAC concentration is more than 50% of its MAV. Replace dose controller with more suitable unit. Manual monitoring and manual chlorine control when quality is variable. 2 Chlorine demand is the difference between the amount of chlorine to the water and the FAC residual remaining after the chlorine has reacted with other substances in the water. If the chlorine demand of the water increases without an increase in the dose, too little disinfectant will remain to disinfect the water properly. 3 The concentrations of disinfection by-products formed, and therefore the risk they present, will depend on the amount of natural organic matter in the water. Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: TOO MUCH FREE AVAILABLE CHLORINE cont’d P7.1.2.5 Chlorine dose solution strength too high. Check that a satisfactory FAC level is produced when a new chlorine container is brought into use. FAC. Chlorine level in chlorine dosing solution. FAC concentration is more than 50% of its MAV. Chlorine levels in dosing solution too high. Determine the cause of the high chlorine and rectify. Provide training in the preparation of chlorine solutions (including P7.1.2.6 Spillage of chlorine compound or solution into dosing solution. Train staff in handling and labelling of chemicals. FAC. Chlorine level in chlorine dosing solution. FAC concentration is more than 50% of its MAV. Chlorine levels in dosing solution too high. Identify the reasons for the spillage and rectify if possible.
treatment-chlorination-feb14-v2.docx