Environmental Engineering Reference
In-Depth Information
The. same. unique. properties. that. make. nanomaterials. so. promising. in. a. wide.
variety.of.industrial,.medical,.and.scientiic.applications.may.pose.challenges.with.
respect.to.wastewater.treatment.
In.2004,.because.the.toxicity.of.nanomaterials.and.
their. fate. and. transport. in. the. environment. were. not. well. understood. at. the. time,.
the. British. Royal. Society. and. the. Royal. Academy. of. Engineering. recommended.
that.“factories.and.research.laboratories.treat.manufactured.nanoparticles.and.nano-
tubes. as. if. they. were. hazardous,. and. seek. to. reduce. or. remove. them. from. waste.
streams”.[1].
Although.the.body.of.research.regarding.the.toxicity,.fate,.and.trans-
port.of.nanoparticles.has.grown.[2],.literature.surveys.in.2006.and.2007.indicate.that.
the.behavior.of.nanomaterials.during.wastewater.treatment.has.not.been.well.studied.
[3,.4].
An.abstract.for.a.research.project.to.evaluate.the.removal.of.various.types.of.
nanoparticles. during. wastewater. treatment,. which. was. funded. by. the. U.S.. EPA's.
National.Center.for.Environmental.Research.(NCER).for.the.period.from.2007.to.
2010,.states:.“Today,.almost.no.information.is.available.on.the.fate.of.manufactured.
nanoparticles.during.biological.wastewater.treatment”.[5].
This.chapter.discusses.the.potential.for.various.treatment.processes.to.remove.
nanoparticles.from.waste.streams.
A.general.description.of.each.process.is.provided,.
as. well. as. an. evaluation. of. how. particular. properties. of. nanomaterials. can. reduce.
or.enhance.the.effectiveness.of.the.process.
Research.indings.are.provided.where.
available,. or. an. indication. is. given. as. to. whether. research. is. ongoing. at. the. time.
of. writing. this. topic.
While. the. primary. focus. is. treatment. processes. in. a. typical.
municipal.wastewater.treatment.plant,.many.of.these.processes.are.used.in.industrial.
wastewater.treatment.
Certain.processes.also.may.apply.to.drinking.water.treatment.
and,.where.relevant,.the.indings.from.water.treatment.research.are.also.discussed.
. Mass balanCe ConsideRations
Concerns. over. the. presence. of. nanoparticles. in. wastewater. streams,. which. could.
eventually.accumulate.in.sewage.sludge.or.discharge.to.the.environment.in.treated.
wastewater,.must.be.put.into.context.
The.concentration.of.a.nanomaterial.in.waste-
water.depends.primarily.on:
•
The.amount.of.local.production.or.use.of.commercial.products.containing.
nanomaterials
Whether.the.nanomaterials.are.ixed.in.a.matrix.(such.as.the.carbon.nano-
tubes.in.a.tennis.racket).or.free.(such.as.TiO
2
.nanoparticles.in.sunscreen)
The.amount.of.the.free.nanomaterial.in.the.product
The.fraction.that.is.washed.down.the.drain
The.degree.of.agglomeration.or.adsorption.occurring.in.aqueous.solution.
that.changes.the.form.of.the.nanoparticle.or.removes.it.from.solution
The.extent.of.dilution
•
•
•
•
•
No.studies.have.been.published.of.which.the.authors.are.aware.that.attempt.to.
quantify.the.discharge.of.nanomaterials.into.wastewater.treatment.plants.
Given.the.
recent.growth.of.the.industry,.the.wide.variety.of.materials.entering.the.market,.and.
the.conidentiality.of.their.formulation,.this.comes.as.no.surprise.
Two.case.studies.
