Environmental Engineering Reference
In-Depth Information
Measurements for Biodegradation
For. screening. the. microbial. growth,. some. studies. measured. the. oxygen.
uptake.in.the.aerobic.degradation.process..Aichinger.et.al..(1992).conducted.
a. research. to. develop. a. respirometric. protocol. for. detecting. low-soluble.
organic.compounds.. They.used.a.modiied.model.to.simulate.the.relation-
ship. between. substrate. concentration,. biomass. concentration,. and. oxygen.
uptakes..The.results.showed.that.the.protocol.can.only.be.applied.when.the.
concentration. of. a. chemical. was. below. its. solubility. limit.. The. proportion.
of. organic. chemicals. above. the. solubility. limit. cannot. be. determined. with.
precision..This.restricted.the.protocol's.application.
However,.if.the.measurement.of.oxygen.consumption.is.to.be.viewed.as.
the.sole.evidence.of.microbial.growth,.it.is.useful.to.record.oxygen.uptakes.
as.demonstrated.in.other.studies.(Wang.et.al..1999,.Juneson.et.al..2001,.Wang.
2004).. Wang. et. al.. (1999). used. calcium. alginate. gel. beads. to. immobilize.
microorganisms. to. degrade. DBP.. The. oxygen. consumption. indicated. that.
the.immobilized.cells.absorbed.oxygen.at.a.lower.rate.than.the.free.cells.with.
reduced. available. oxygen.. Juneson. et. al.. (2001). measured. oxygen. uptakes.
to.conirm.whether.the.sequencing.batch.reactor.(SBR).system.has.a.higher.
degradation. rate. than. standard. batch. reactor. and. found. evidence. afirm-
ing. the. higher. degradation. rate. possible. with. using. the. SBR.. Wang. (2004).
also.compared.the.degradation.ability.of.unacclimated.activated.sludge.ver-
sus. acclimated. activated. sludge.. The. results. showed. that. activated. sludge.
eliminated. higher. COD. when. acclimated. in. 300.mg/L.and. that.it.was.able.
to. degrade. DBP. better. than. the. unacclimated. activated. sludge.. The. unac-
climated. activated. sludge. was. found. to. inhibit. the. oxygen. uptake. process.
when.the.DBP.concentration.is.at.a.higher.level..However,.the.opposite.was.
found. for. to. be. the. case. for. acclimatedly. activated. sludge;. the. uptake. rate.
slightly.increased.with.the.rise.of.substrate.concentration..Sharanagouda.and.
Karegoudar.(2000).used.fungal.strain. A. niger .to.degrade.DMP.and.proved.
that.the.cell.grown.with.DMP.as.a.sole.substrate.had.a.higher.oxidation.abil-
ity.than.those.grown.in.glucose,.by.measuring.the.oxygen.consumption.
The.CO 2 .evolution.test.is.frequently.used.as.part.of.the.biodegradation.
experiment. to. evaluate. the. extent. of. degradation. process.. Gledill. (1975).
mentioned. CO 2 . evolution. can. assess. the. ultimate. level. of. biodegradation.
(Sharanagouda. and. Karegoudar. 2000).. Sugatt. et. al.. (1984). determined. 14.
biodegradable.PAEs,.on.the.basis.of.shake-lask.CO 2 .evolution..The.level.of.
BBP.and.DTDP.found.was.no.more.than.80%.for.primary.degradation.and.
50%.for.ultimate.degradation..The.primary.degradation.was.expressed.by.
the. loss. of. PAEs. during. the. degradation. process,. and. the. ultimate. deg-
radation. was. expressed. by. the. difference. between. the. percentage. of. CO 2 .
actually. measured. and. the. theoretical. CO 2 . value. set. for. the. experiment..
Comparison. of. these. results. indicated. the. existence. of. an. important.
relationship. between. bacterial. utilization. and. chemical. degradation..
Recently,.an.improvement.on.the.CO 2 .evolution.test.method.was.proposed.
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