Environmental Engineering Reference
In-Depth Information
and. particulate. matter;. however,. this. interpretation. may. not. be. correct..
Snyder.et.al..(2007).presented.much.more.data.from.their.study,.and.it.is.up.
to.the.readers.to.digest.the.information.and.to.draw.their.own.conclusions.
from.them.
The. traditional. POSTW. removes. POPs. and. CECs. based. on. sorption. and.
biodegradation..It.would.be.desirable,.therefore,.to.make.use.of.removal.data.
to. show. the. sorption. and. biodegradation. properties. of. target. compounds..
Snyder.et.al..(2007).had.selected.29.target.compounds.for.an.extensive.study,.
and.the.results.are.presented.in.Table.8.2.where.the.sorption.and.biodegra-
dation. properties. were. interpreted. and. rated. as. low. (L),. medium. (M),. and.
high. (H).. The. data. from. other. literature. reviews. were. studied. before. the.
biodegradation. property. for. each. CEC. was. assigned,. especially. when. the.
biosorption.level.was.strong.and.the.biodegradation.properties.could.not.be.
deduced.from.the.original.data..The.data.as.presented.in.Table.8.2.were.from.
experiments.with.relatively.clean.river.water.and.not.from.sewage.inluent..
The.studies.have.reported.that.the.overall.removal.rates.of.POPs.and.CECs.
in.full-scale.POSTWs.clearly.show.that.their.elimination.is.often.incomplete.
(Table. 8.3).. As. a. consequence,. signiicant. fractions. of. POPs. and. CECs. are.
discharged.with.the.inal.efluent.either.into.the.aquatic.environment.or.into.
sludge. discharge.. The. deposition. of. POPs. and. CECs. on. land. from. sludge.
reapplication. can. be. another. signiicant. pathway. for. releasing. these. sub-
stances.into.the.environment..Studies.report.on.the.removal.of.the.POPs.and.
CECs.by.comparing.inluent.and.efluent.concentrations,.but.without.distin-
guishing.between.the.three.major.fates.of.a.substance.in.POSTWs,.which.are.
as.follows:.(a).degradation.to.lower-molecular-weight.inactive.fractions,.(b).
degradation.to.smaller.or.aggregation.to.higher-molecular-weight.but.active.
species,.and.(c).physical.sorption.to.solids.and.removed.as.sludge.
Compounds. with. either. properties. of. sorption. or. biodegradation. can. be.
removed. by. sewage. treatment. systems. effectively;. however,. compounds.
that. lack. such. properties,. such. as. carbamazepine. and. iopromide,. will.
persist. in. the. efluent. for. a. long. time. as. shown. in. Tables. 8.2. and. 8.3.. The.
removal. eficiencies. of. diclofenac. and. ibuprofen. are. quite. similar. to. each.
other,. as. reported. for. several. POSTWs. that. are. located. all. over. the. world..
The.results.indicated.that.the.elimination.of.such.compounds.seems.unre-
lated. to. the. designs. of. each. POSTW.. The. reported. removal. eficiencies. of.
hormones,.including.estrone,.17-β-estradiol,.and.17-α-ethinyl-estradiol,.were.
found. to. vary. greatly. between. studies,. which. can. be. demonstrated. by. the.
following. different. behaviors. observed:. (a). an. increase. along. the. passage.
of. the. POSTW. (Baronti. et. al.. 2000,. Carballa. et. al.. 2004),. (b). no. signiicant.
removal. (Ternes. et. al.. 1999a),. and. (c). eficiencies. higher. than. 80%. (Ternes.
et. al.. 1999b,. de. Mes. et. al.. 2005,. Nakada. et. al.. 2006).. However,. the. factors.
that.may.explain.these.deviations.cannot.be.fully.elucidated,.since.many.of.
the. cases. did. not. report. adequate. operational. data.. Complete. oxidation. of.
17-β-estradiol.to.estrone.would.be.expected.to.occur.in.less.than.3.h,.whereas.
further. oxidation. of. estrone. should. occur. at. a. slower. rate. (50%. after. 24.h),.
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