Abstract:
The use of pesticides in modern agriculture is necessary in order to
maintain high crop yields, however this use of pesticides can risk contamination
of potable water sources. In order to prevent potable water contamination, the
movement of pesticides out from agricultural environments must be prevented.
In this work, adsorption media has been considered as a means to do this as it
can be used without external energy requirements and so can be used in
remote locations such as farmland catchments. To understand the issue of
pesticides in drinking water in the UK, a study on pesticide water quality
compliance was conducted using data available from the Drinking Water
Inspectorate water quality regulator. From this, a number of pesticides were
identified to be of particular concern. The physico-chemical properties of these
pesticides were then established and adsorption media suitable for their
removal from water was identified. A field study was conducted to understand
the specific conditions under which pesticide run-off occurs using a new
sampling methodology that was proportional to the local rainfall. The work then
researched in-field adsorption solutions for pesticide removal. This was
investigated by using different activated carbon media and determining their
speed and efficiency at removing three identified pesticides: metaldehyde,
metazachlor and propyzamide. The practical applicability of each medium was
then considered by understanding the headlosses that might be observed at a
range of realistic flow rates as observed in the field study. This resulted in the
selection of an activated carbon fabric for pilot testing in flowing water as a
result of its superior kinetic uptake and its effective performance in a complex
matrix (raw water) when compared with the other media tested. In addition, the
ability to orientate the fabric into a range of practical and flexible configurations
will enable reduced headlosses in agricultural environments. The results
showed that the activated carbon medium had great potential, achieving
approximately 46% removal of the pesticide metaldehyde during flume
experiments.
