Event: NOT ALL THE MANGANESE REMOVED cont’d P8.2.1.12 During design do pilot Manganese. Manganese Replace or trials to check that concentration is modify the Poor design of the type of aerator more than 50% aerator. aerator. chosen, and its of the MAV. design, will provide No sign of adequate oxidation of insoluble the metals. manganese formation directly after oxidation (metals must be insoluble to be removed). show design is unsatisfactory. P8.2.1.13 See P6 Guide series for a discussion of events, causes, preventive measures etc. associated with the use of standard filters, and those using greensand for combined Poor removal oxidation and filtration. of precipitated metal by filtration. P8.2.1.14 Ensure KMnO4 dose Manganese. Manganese Adjust dose (in the influent, or in concentration is rate. Greensand off-line regeneration) more than 50% performance Undertake a is adequate to of the MAV. inadequate. more maintain the oxidising No sign of complete capacity of the bed. insoluble check on the Ensure that manganese water concentrations of formation chemistry and other chemically directly after reconsider reduced oxidation this treatment determinands in the (metals must be option if water (eg, organic insoluble to be reduced matter, nitrite, removed). determinand ammonia and hydrogen sulphide) are high. are not so high that Modify they exhaust the operational bed’s oxidising procedure. capacity. Start a filter Provide sufficient maintenance time for the bed to programme. after bringing “ripen” it back on-line. Schedule routine filter maintenance. This should check for channelling for example (see also Guide P6.1). P8.2.1.15 Provide stand-by Continuity of Loss of power. Refuel generator to ensure power. generator, if Power failure. continuity of power. appropriate. Event: OXIDANT DOSE TOO HIGH Possible hazards: Manganese (if KMnO4 used as an oxidant), chlorine, chlorine dioxide or KMnO4. Level of risk: Moderate
Event: NOT ALL THE MANGANESE REMOVED cont’d P8.2.1.12 Poor design of aerator. During design do pilot trials to check that the type of aerator chosen, and its design, will provide adequate oxidation of the metals. Manganese. Manganese concentration is more than 50% of the MAV. No sign of insoluble manganese formation directly after oxidation (metals must be insoluble to be removed). show design is unsatisfactory. Replace or modify the aerator. P8.2.1.13 Poor removal of precipitated metal by filtration. See P6 Guide series for a discussion of events, causes, preventive measures etc. associated with the use of standard filters, and those using greensand for combined oxidation and filtration. P8.2.1.14 Greensand performance inadequate. Ensure KMnO4 dose (in the influent, or in off-line regeneration) is adequate to maintain the oxidising capacity of the bed. Ensure that concentrations of other chemically reduced determinands in the water (eg, organic matter, nitrite, ammonia and hydrogen sulphide) are not so high that they exhaust the bed’s oxidising capacity. Provide sufficient time for the bed to “ripen” after bringing it back on-line. Schedule routine filter maintenance. This should check for channelling for example (see also Guide P6.1). Manganese. Manganese concentration is more than 50% of the MAV. No sign of insoluble manganese formation directly after oxidation (metals must be insoluble to be removed). Adjust dose rate. Undertake a more complete check on the water chemistry and reconsider this treatment option if reduced determinand are high. Modify operational procedure. Start a filter maintenance programme. P8.2.1.15 Power failure. Provide stand-by generator to ensure continuity of power. Continuity of power. Loss of power. Refuel generator, if appropriate. Event: OXIDANT DOSE TOO HIGH Possible hazards: Manganese (if KMnO4 used as an oxidant), chlorine, chlorine dioxide or KMnO4. Level of risk: Moderate
treatment-iron-manganese-removal-feb14-v2.docx