Environmental Engineering Reference
In-Depth Information
techniques.available.in.detecting.them.at.concentrations.as.low.as.1.ng/L..
Literature.reviews.on.wastewater.treatments.showed.that.many.POPs.and.
CECs. are. only. partially. removed. by. typical. sewage. treatment. processes.
(Pickering.and.Sumpter.2003)..The.main.removal.pathways.for.the.removal.
of.POPs.and.CECs.during.wastewater.treatment.processes.are.the.following.
(Birkett.and.Lester.2003):
•. Compounds.being.adsorbed.onto.suspended.solids
•. Compounds.going.through.aerobic.and.anaerobic.biodegradation
•. Compounds.going.through.hydrolysis
•. Compounds.going.through.volatilization.into.the.air.space
A. completed. public-owned. sewage. treatment. works. (POSTW). would.
include. physical,. biological,. and. chemical. treatment. processes. in. order. to.
remove. any. corresponding. contaminants,. where. each. sewage. treatment.
generally. involves. three. stages. called. primary,. secondary,. and. tertiary.
treatments.. More. than. one. tertiary. treatment. process. may. be. used. at. any.
treatment. plant. in. which. its. purpose. is. to. provide. a. inal. treatment. stage.
to.raise.the.efluent.quality,.before.it.is.discharged.into.the.receiving.envi-
ronment. such. as. seas,. rivers,. lakes,. and. ground.. Sometimes,. the. conver-
sion.of.toxic.ammonia.to.nitrate.alone.is.referred.to.as.a.tertiary.treatment..
“Efluent.polishing”.is.the.term.used.when.chemical.disinfection—such.as.
with.NaOCl,.ozone,.or.physical.disinfection,.or.with.UV.radiation,.microil-
tration,.and.so.on—is.involved.in.treatment.and.is.always.the.inal.process.
if.present..Only.advanced.sewage.treatment.facilities.include.three.stages.of.
treatment,.whereas.most.other.facilities.will.only.include.the.primary.stage.
or.a.combination.of.primary.and.secondary.treatments.
The. major. objectives. for. this. review. came. about. in. light. of. the. indings.
from.the.literature,.which.examined.the.removal.of.contaminants.by.drink-
ing-water.and.sewage.treatment.processes..The.objectives.were.to.evaluate.
the.removal.eficiencies.of.groups.of.POPs.and.CECs.in.POSTW.and.to.sug-
gest.other.alternatives.if.removal.eficiencies.were.insuficient.
BackgroundonPOPsandCECs
The.United.Nations.Environment.Programme.Governing.Council.in.May.of.
1995.decided.to.begin.investigating.POPs,.with.a.short.list.of.12.compounds,.
known.as.“the.dirty.dozen”:.aldrin,.chlordane,.DDT,.dieldrin,.endrin,.hepta-
chlor,. hexachlorobenzene,. mirex,. PCB,. polychlorinated. dibenzo-p-dioxins,.
polychlorinated. dibenzofurans,. and. toxaphene.. Since. then,. this. list. has.
been. extended. to. include. PAHs. and. certain. brominated. lame. retardants..
Search WWH ::
Custom Search