Environmental Engineering Reference
In-Depth Information
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Unclear.fate.of.nZVI.after.a.spill.dries..If.spilled.nZVI.forms.iron.hydrox-
ides.and.salts,.then.risk.would.be.minimal..If.the.reaction.produces.nano-
sized. iron. oxide. particles,. additional. information. would. be. needed. on.
environmental.fate.and.toxicology.
Unknown.sensitivity.of.human.skin.to.nZVI.(and.some.concern.due.to.high.
pH.of.solution).
Ultimate.fate.of.injected.nZVI.unknown..Products.likely.to.be.soluble.iron.
hydroxides. and. salts,. which. would. present. no. long-term. concerns.. If. the.
reaction.produces.nano-sized.iron.oxide.particles,.then.additional.informa-
tion.is.needed.on.environmental.fate.
Insuficient. nZVI,. contact. time,. and/or. untested. reactions. can. result. in.
incomplete.contaminant.destruction..“Careful.design.and.testing.of.treat-
ment.systems.is.necessary.to.avoid.these.potential.problems.”
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Following.are.brief.descriptions.of.instances.where.those.responsible.for.ground-
water.remediation.have.chosen.to.use.nZVI.
10.1.6
C
ase
s
tudies
Table.10.1. summarizes. several. case. studies. of. the. use. of. nZVI.. Two. projects. are.
described.below.in.more.detail.
0...
nease Chemical site
Formerly.a.chemical.manufacturing.plant,.the.Nease.Chemical.Site.in.Ohio.is.now.
on.the.National.Priorities.List.of.Superfund.sites..Soil,.sediment,.and.groundwater.
contain.over.150.contaminants,.primarily.chlorinated.compounds..In.2005,.the.U.S..
EPA.signed.a.Record.of.Decision.that.included.treatment.of.groundwater.in.bedrock.
by.nZVI..Subsequent.work.has.included.bench-.and.pilot-scale.studies.[29-31].
Volatile.organic.compounds.(VOCs).contaminate.groundwater.in.both.overbur-
den.and.bedrock.aquifers..The.overburden.varies.from.silty.sand.to.silty.clay..Bed-
rock,.comprising.sandstone,.is.fractured.and.groundwater.low.occurs.primarily.in.
fractures..Dense.nonaqueous.phase.liquid.(DNAPL).contaminates.the.bedrock.and.
the. concentration. of. total. dissolved. VOCs. exceeds. 100. mg/L.. VOCs. include. tet-
rachloroethylene.(or.perchloroethylene,.abbreviated.PCE),.trichloroethylene.(TCE),.
cis
-1,2-dichloroethylene.(DCE),.dichlorobenzene,.and.benzene.
The.initial.bench-scale.test.examined.the.following.factors:
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Treatment.of.both.chlorinated.and.nonchlorinated.contaminants
Form.of.nZVI,.including.four.different.materials.(mechanically.produced.
or.chemically.precipitated.nZVI,.with.and.without.palladium.catalyst)
nZVI.dosage.ranging.from.0.05.to.10.g/L
Inluence.of.site.soils
Generation.of.byproducts
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