Environmental Engineering Reference
In-Depth Information
Other PhACs and PCPs
PhACs. include. prescription. drugs,. over-the-counter. medications,. drugs.
used. in. hospitals,. and. veterinary. drugs.. After. intake,. drugs. are. generally.
absorbed. and. subjected. to. further. metabolic. reactions,. including. hydroly-
sis,.alkylation.and.dealkylation,.and.oxidation.and.reduction.of.the.parent.
compound.. Another. major. route. of. interaction. is. forming. conjugates. such.
as. glucuronides. and. sulfonates. to. enhance. excretion. (Cunningham. 2004)..
Signiicant.portion.of.PhAC.remains.unmetabolized.and.is.excreted.out.of.
the.body.in.urine.or.feces..In.addition,.other.sources.of.PhACs.that.enter.the.
environment.are.ones.that.are.directly.discarded..Concentrations.of.PhACs.
in. wastewater. treatment. inluent. were. estimated. to. range. from. less. than.
1.ng/L. to. approximately. 130,000.ng/L,. but. the. majority. were. between. 100.
and.1,000.ng/L.(AWWARF.2007).
PCPs.include.products.for.personal.health.and.cosmetic.purposes.such.as.
fragrances,. lotions,. and. cosmetics.. Currently,. the. most. commonly. detected.
compound. from. PCPs. is. triclosan,. a. potent. wide-spectrum. antibacterial.
and.antifungal.agent..Triclosan.is.used.primarily.in.soaps,.toothpastes,.and.
detergents.
CurrentInformationontheRemovalof
POPsandCECsinPOSTW
Typical.wastewater.treatment.facilities.are.designed.to.meet.efluent.quality.
parameters.such.as.TSS,.BOD,.and.COD.and.would.involve.one.to.three.stages.
of.sewage.treatment.referred.as.primary,.secondary,.and.tertiary.treatment..
Some. POSTW. utilize. only. the. primary. treatment. stage,. whereas. modern-
ized.types.have.adopted.both.the.primary.and.secondary.treatment.stages.
and. more. advanced. POSTW. have. incorporated. all. three. stages. of. sewage.
treatment..POPs.and.CECs.cover.a.broad.range.of.chemical.structures.with.
diverse. physical. properties. such. as. molecular. weight,. water. solubility. and.
dissociation. constant. (pKa),. octanol-water. partition. coeficient. (Kow),. and.
charge.density..A.single.treatment.process.cannot.be.designed.to.remove.all.
POPs.and.CECs.from.sewage.inluent.
The primary treatment process
.in.a.POSTW.involves.coagulation,.loccula-
tion,.and.chemical.softening.in.order.to.separate.suspended.solids.during.
water. treatment.. Coagulation. uses. iron. or. aluminum. salts. to. precipitate.
metal.hydroxides..Softening.involves.the.use.of.lime.or.soda.ash.to.remove.
calcium.(at.pH.≥.9).and.magnesium.(at.pH.≥.11)..Both.coagulation.and.soft-
ening.remove.suspended.solids.and.colloidal.material;.meanwhile.organic.
compounds.are.absorbed.into.the.suspended.particles.and.removed.with.
the. solid. particles.. Synthetic. polymers. with. positively. charged. groups,.
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