Environmental Engineering Reference
In-Depth Information
(Strotmann. et. al.. 2004).. The. improved. test. system. was. found. to. be. more.
suitable.for.poorly.water-soluble.and.high-volatile.chemicals.
Anaerobic Degradation
Apart.from.aerobic.degradation,.some.of.the.studies.focused.on.bioremedia-
tion.under.anaerobic.condition..The.main.anaerobic.biodegradation.methods.
involve.using.activated.sludge,.acclimated.activated.sludge,.biomass.support.
particles,. and. methanogenic. consortia. to. degrade. several. PAEs,. including.
DMP,.DMIP,.and.DMTP..As.early.as.1985,.activated.sludge.applied.to.degrade.
commercial.phthalate.esters.was.reported.by.O'Grady.et.al..The.procedure.
was. designed. using. two. different. tests,. a. semicontinuous. activated. sludge.
test.and.an.acclimated.19.day.die-away.procedure.(O'Grady.et.al..1985)..The.
results.showed.that.within.5.days.most.of.the.PAEs.could.be.eliminated.down.
to.less.than.20%.of.the.original.level,.demonstrating.that.most.of.the.PAEs,.
including. DMP,. DEP,. and. DEHP,. were. eliminated. by. the. activated. sludge..
Detailed.kinetics.of.anaerobic.degradation.by.the.acclimated.activated.sludge.
was.presented.in.another.study.(Wang.et.al..1996b)..DMP.showed.the.fast-
est.degradation.rate.with.
k
1
.(0.033/h).and.
t
1/2
.(21.0.h),.but.di-
n
-octyl.phthal-
ate.(DnOP).was.found.having.the.slowest.degradation.rate..Apparently,.the.
kinetics.constant.of.biodegradation.was.found.to.be.correlated.to.the.kinet-
ics.constant.of.hydrolysis.rate..Other.new.techniques.like.biomass.support.
particles. were. also. introduced. in. the. treatment. of. organic. pollutants.. The.
bacterial.biomass.was.immobilized.to.be.applied.in.the.bioreactors.on.sup-
port. particles. such. as. polyurethane. reticulated. foam.. Sharma. et. al.. (1994).
reported.the.existence.of.high.levels.of.COD.on.the.basis.of.an.experiment.
conducted. using. wastewater. lux. from. a. DMTP. manufacturing. plant.. The.
biomass.support.particles.were.applied.to.treat.the.waste.water.outlow..The.
system.had.a.longer.sludge.retention.time.(SRT).than.the.unsupported.bio-
mass.particles,.which.implies.a.higher.tolerance.to.the.toxicity.of.the.outlow..
Although.no.concentration.of.DMTP.was.stated.in.the.report,.biomass.sup-
port.particles.could.be.applied.to.degrade.various.PAEs,.including.DMTP.
Several. works. regarding. the. anaerobic. degradation. of. phthalate. iso-
mers. by. consortia. were. published. in. 1999. (Kleerebezem. et. al.. 1999a,b,c,d)..
In. one. such. work,.
ortho
-phthalate,. isophthalate. terephthalate,. DMP,. DMTP,.
para
-toluate,. and.
para
-xylene. were. all. tested. for. their. biodegradability. by.
the. anaerobic. consortium. (Kleerebezem. et. al.. 1999b).. Results. showed. that.
three. isomers,. namely,. dimethylphthalate,. isophthalate,. and. terephthal-
ate,. are. the. substrates. that. had. different. a. lag. phase. and. in. the. sequence.
dimethylphthalate.<.terephthalate.<.isophthalate. occurring. over. a. period. of.
17-156.days..This.sequence.might.relect.the.methanogenic.activity.of.cultures.
that. degrades. these. three. isomers. and. is. closely. related. to. the. amounts. of.
these.isomers.appearing.in.the.environment..For.exploring.the.internal.rela-
tionship. among. different. species. and. their. contribution. in. the. cooperation,.
Kleerebezem.conducted.a.broad.investigation.on.the.anaerobic.biodegradation.
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