The efficacy of inclined tube and plate modules in a high lime clarification process

The introduction of inclined tube and plate modules into the upper section of a high lime clarifier effected a decided improvement in the quality of the overflow. The performance of these modules, within defined limits, was relatively insensitive to pH, hydraulic loading and temperature. However, flocculant dosage and clarifier turbidity strongly influenced module performance. The modules became particularly useful at clarifier turbidities in excess of three Jackson turbidity units, effecting reductions in the carry-over of suspended material of more than 50%. In a high lime process, these modules would require at least a three-monthly hosing and brushing down. Annual acid washes would most probably be required to ensure satisfactory continuous operation.