In this study, the efficiency of different types of
pulsed electrical discharges for the removal of organic pollutants from
wastewater has been determined. Three discharge types, either in the water
volume or in close proximity to the water surface are studied. The
production of hydrogen peroxide in pure water, and the degradation of two
typical pollutants (4-chlorophenol and 4-nitrophenol) is measured together
with the amount of electrical energy dissipated in discharges. It is shown
that the energy yield for the degradation of organic pollutants, expressed
in terms of degraded moles per Joule, strongly depends on the discharge
type. The highest efficiency is obtained with pulsed corona discharges in
humid air above the water surface. A lower efficiency is found with spark
discharges in water, and the less efficient process is constituted by
streamer discharges in water. The influence of ferrous ions added to
solutions is also very different according to the discharge type. This helps
to get a better understanding of the degradation processes involved with the
different discharge types.