SURVEY OF THE EFFECTIVENESS OF OZONE AND ULTRAVIOLET LIGHT IN REDUCING THE CONCENTRATION OF PESTICIDES IN DRINKING WATER (WTT 981 SLG)
Report No DWI0114

Aug 1989

SUMMARY

I OBJECT

The objective of this work was to perform a review of available literature with the aim of determining the suitability of ozone and ultra-violet light for treating water containing pesticides.

II REASONS

Water Authorities and companies have been proposing the use of ozone and/or ultra-violet light in water treatment for the removal of one or more pesticides from drinking water. The Department of the Environment (DoE) have been concerned that programmes for capital expenditure in this area are based on inadequate process design data for some of the pesticides present in water. Therefore, they commissioned WRc to perform a literature review to assess the potential of ozone, as well as ultra-violet light, to reduce concentrations of any of the 19 pesticides that have been detected in drinking water supplies at concentrations above the EC Directive standard from water.

III CONCLUSIONS

The overall conclusion from the study is that there is very little experience with the use of ozone and/or ultra-violet light to remove any of the pesticides on the DoE list of 19 from water. Of the list of 19 there is only information on 8 that relates to the two processes. These are atrazine, simazine, propazine, linuron, 2,4-D, MCPA, MCPB and malathion.

Most of the information available is from laboratory scale work, with high pesticide concentrations at the mg/l level. Ozone is effective at removing pesticides at these concentrations, but the results indicate that the reactivity is low.

Contact times of greater than 15 minutes are required for pesticide removal. However, from the published data it is not possible to demonstrate a relationship between contact time and degree of removal.

No assessment of the required dose was possible for individual pesticides. Therefore, no cost estimates were possible for the removal of pesticides by ozone.

IV RECOMMENDATIONS

The lack of information about the removal of pesticides from water by ozone and/or ultra-violet light indicates that there is a need for more work to be performed in this area, particularly for the listed pesticides encountered in drinking water at concentrations above the EC Directive standard.

V RESUME OF CONTENTS

A review of literature related to the use of ozone and/or ultra-violet light for the control or removal of the listed pesticides from water is presented.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.