The unexpected similar increase in BODf for the
filtered and nonfiltered effluents is likely the result of the low
sensitivity of the measurement method, especially at the low
BOD range. TSS and CODf remained relatively unchanged for
the nonfiltered effluent while an increase in TSS and a decrease
in CODf were observed in the filtered effluent. The increase in
TSS in the filtered sample may indicate the formation of
particles (and TSS) by ozone-induced polymerization/flocculation
of DOM.11,16 This phenomenon was not seen in the
nonfiltered effluent, probably due to equilibrium between the
formation and disintegration of particles by ozone. The
decrease in CODf by ozone in the filtered effluent, as opposed
to the unchanged CODf level in the nonfiltered effluent,
demonstrates once again the simultaneous reaction of ozone
with particles and DOM (thus with less particles, more ozone
reacts with DOM).