Advances in Water Treatment and Enviromental Management

GROUNDWATER POLLUTION BY VOLATILE ORGANIC SOLVENTS 213ii)iii)Assuming 2 pumps operatingFlow equivalent 2 pumps 10 hours+1 pump 14 hoursActual Theoretical Transfer EfficiencyK L a K L a %Case 1 23.5 59.1 40Case 2 50.5 99.5 51Case3 34.3 77.2 44All of these transfer efficiencies are considerably higher than that achieved duringcommissioning and it is therefore clear that a significant change in performance occurredbetween commissioning and operation.It has long been known that etching of packing has the effect of increasing the specific surfacearea and therefore increasing mass transfer rates. Improvements in mass transfer performanceof up to 50% have been observed from such effects (Norman and Soloman, 1959). Precipitationof calcium carbonate scale upon packing surfaces might cause such improvements but theFig 9 Removal of trichtoroethene by Air Stripping (Case B)