Advances in Water Treatment and Enviromental Management

GROUNDWATER POLLUTION BY VOLATILE ORGANIC SOLVENTS 211Fig 8 Removal of trichloroethene by Air Stripping (Case A)Snowflake Type II and this was the first occasion that this has been used for such applicationsin the UK although experience exists in the USA. This packing has the benefit of a low pressuredrop thereby allowing the full flow to pass through a single tower in the event of a fan failure.As stated in Section 2 the well has a history of organic contamination and therefore activatedcarbon was installed after the stripping columns as a “polishing” stage.Removal efficiencies specified were 88% for TCE 90%, PCE and 80% for CTC.CommissioningPoor removal efficiencies were observed during the commissioning of the works. As can beseen from the results in Table 2, the TCE removal was only 72% as compared with a designvalue of 88%.Clearly the performance fell considerably short of the target with K L a from Eq 3 equal to 26.2.The theoretical value of K L a expected for the towers as designed (calculated from Eq 4) was 99.5