Most tastes and odors in water supplies come from naturally-occurring
or manmade organic material contamination. Bacterial decomposition of
humic material imparts taste to surface waters. The action of algae and
actinomycetes gives rise to objectionable tastes. Chlorination of humic
material leads to chlorophenols that are of far stronger odor and more
antigonistic to taste than the original phenol and unreacted Chlorine.
Most of these odors are removed with Ozone treatment. Even some sulphur
compounds such as hydrogen sulfide, mercaptans or organic sulphides can
be oxidized to Sulfates with Ozone.