I

SUMMARY

OBJECT

II

III

The objective of this work was to perform a review of available

literature with the aim of determining the suitability of granular (GAC)

and powdered (PAC) activated carbon for treating water containing

pesticides.

REASONS

Water Authorities and companies have been proposing the use of GAC in

water treatment for the removal of one or more pesticides from drinking

water. The DOE have been concerned that the applications 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 GAC to reduce

concentrations of any of the 19 pesticides (that have been detected in UK

drinking water supplies at concentrations above the EC Directive

standard) from water.

CONCLUSIONS

The overall conclusion from the study would be that there is very little

experience with the use of GAC to remove any of the pesticides on the DoE

list of 19 from water. Of the list of 19 pesticides, there is information

about only 7 pesticides that relate to the use of GAC for their removal.

These were atrazine, simazine, propazine, 2,4-D, linuron, malathion and

MCPA .

The type of information available on these 7 pesticides varied from

detailed pilot and full scale process performance to laboratory isotherm

tests. GAC was capable of removing or reducing to below O,lpg/l, all of

these compounds from water but the capacity of the GAC for these

compounds varied widely. Of these 7 pesticides all but malathion and MCPA

were apparently strongly adsorbed by GAC.

(i)

A WRc cost model for adsorption onto GAC was used to compare the costs of

removing these 7 pesticides from water. The costs were estimated for a

range of plant water throughputs and pesticide concentrations. However,

for a plant treating lOMUd of water containing 5ug/l of pesticide, the

increased cost of water resulting from GAC treatment ranged from about

1.9p/m3 for simazine to about 8.1p/m3 for malathion.

IV RECOMMENDATIONS

The lack of information about the removal of pesticides from water by GAC

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 REsd OF CONTJSNTS

A review of literature related to the use of activated carbon for the

control or removal of the listed pesticides from water is presented. The

data, presented in the papers found, is reproduced as isotherms and/or

volumes of water treated per kg carbon in column tests. Where possible

operating conditions have been given.

The best isotherm and GAC capacity data have been used to develop costs

for treating water, contaminated by individual pesticides. It is hoped

that this allows a relative comparison between the effectiveness of GAC

to treat pesticide contaminated water to be made.

(ii)