turbidity is Routine monitoring Start or more than 0.2 of coagulant monitoring iron, or NTU residuals in filtered programme. polymer. water. colour is more than 10 TCU aluminium residual is more than 0.15 mg/L elevated residual levels of other coagulants. 1 The consequences of the event, and therefore the level of risk, will be influenced by the quality of the source water and the effectiveness of treatment processes after coagulation, flocculation and flotation, ie, filtration and disinfection. Preventive measures Checking preventive measures Corrective action Causes What to check that action is needed Event: PARTICLES NOT REMOVED cont’d P5.2.1.2 Determine and Plant flow No jar test Determine document rate. records. relationships Dosing rates relationships and document. set incorrectly Chemical No dosing control between source or dosing based on source Install water quality and flows. water quality. appropriate coagulant type and dosing control Visual Elevated turbidity, demand, flocculant equipment. inspection colour and type and demand, for floc residual coagulant Adjust dose and optimum pH. stability. in filtered water. rates. Make sure that Source and chemical dosing is post-filter: able to respond to changing source turbidity water quality and colour quantity, ie, pH appropriate choice of manual, flow alkalinity proportional or coagulant automatic dose and/or control (eg, streaming current detector, colour, turbidity). P5.2.1.3 Stand-by generator. Electricity Poor continuity of Obtain a supply. power supply. generator or Power failure. alternative power source. Refuel generator if necessary.
or iron, or polymer. turbidity is more than 0.2 NTU colour is more than 10 TCU aluminium residual is more than 0.15 mg/L elevated residual levels of other coagulants. Routine monitoring of coagulant residuals in filtered water. Start monitoring programme. 1 The consequences of the event, and therefore the level of risk, will be influenced by the quality of the source water and the effectiveness of treatment processes after coagulation, flocculation and flotation, ie, filtration and disinfection. Causes Preventive measures Checking preventive measures Corrective action What to check that action is needed Event: PARTICLES NOT REMOVED cont’d P5.2.1.2 Dosing rates set incorrectly or Determine and document relationships between source water quality and coagulant type and demand, flocculant type and demand, and optimum pH. Make sure that chemical dosing is able to respond to changing source water quality and quantity, ie, appropriate choice of manual, flow proportional or automatic dose control (eg, streaming current detector, colour, turbidity). Plant flow rate. Chemical dosing flows. Visual inspection for floc stability. Source and post-filter: turbidity colour pH alkalinity coagulant and/or No jar test records. No dosing control based on source water quality. Elevated turbidity, colour and residual coagulant in filtered water. Determine relationships and document. Install appropriate dosing control equipment. Adjust dose rates. P5.2.1.3 Power failure. Stand-by generator. Electricity supply. Poor continuity of power supply. Obtain a generator or alternative power source. Refuel generator if necessary.
treatment-dissolved-air-flotation-feb14-v2.docx