Mixed Contamination of Polyaromatic Hydrocarbons and Metals at Manufactured Gas Plant Sites: Toxicity and Implications to Bioremediation - Environmental Contamination: Health Risks and Ecological Restoration - page 352

TABLE 16.1
Summary.of.the.Principal.Waste.Types.at.Gasworks.Sites

PrincipalWasteType Source Contaminants

Coal.tar
Tar.oils

Separated.from.gas.and.liquors.at.
various.stages.of.the.puriication.
processes

PAHs
Petroleum.hydrocarbons,.
including.BTEX
Phenols
Complex.cyanides

Spent.oxides Used.to.remove.sulfur.during.gas.

puriication

Free.cyanides
Metals

Coke,.coke.breeze,.ash,.
clinker.residues

By-products.and.furnace.residues PAHs

Metals

Light.oils Light.oils.used.around.all.

machinery.and.as.scrubbing.agent.
in.recovery.process

Petroleum.hydrocarbons.
(including.BTEX)

Drip.oils Drip.oils.condensed.from.gas

Ammoniacal.wastes Nitrogen.removal.during.gas.

puriication.processes

Phenols,.nitrates,.sulfates,.
sulides,.PAHs

Asbestos Used.as.lagging.around.many.of.the.

“hot”.processes.and.pipes

Asbestos

Pb,.mercury,.Zn Pb.from.batteries,.pipelines,.paints,.

etc..Mercury.sometimes.used.in.
metering.switches

Metals

Source: . New.South.Wales.Environmental.Protection.Agency.(NSW.EPA),.Information.about.

assessing.gasworks.sites,.Department.of.Environment.and.Conservation,.New.South.
Wales,. Australia,. http://www.environment.nsw.gov.au/clm/gasworksassessment.
html,.2005.

Coal.or.water-gas. tar,.the.primary.by-products.of.gas.manufacture.from.
MGP. sites,. are. of. particular. concern. because. elevated. PAH. concentrations.
and.tar.form.a.dense.nonaqueous.phase.liquid.(DNAPL).that.is.capable.of.
migrating.downward.in.the.subsurface.below.the.water.table..Thus,.the.sub-
surface.of.old.gasworks.sites.consists.of.a.mixed.ill.contaminated.with.coal.
tar. and. its. distillation. products,. organics,. and. heavy. metals.. The. contami-
nants. are. heterogeneously. distributed,. but. are. found. throughout. the. area..
Several. authors. reported. the. presence. of. PAHs. and. metals. together. in. the.
former.MGP.sites.(Thomas.and.Lester.1994,.Haeseler.et.al..1999,.Reddy.et.al..
2006,. Thavamani. 2010,. Thavamani. et. al.. 2011).. The. PAH. concentrations. in.
MGP.sites.varied.from.150.to.40,000.mg/kg,.and.most.of.the.studies.reported.
a. total. PAH. concentration. >10,000.mg/kg. (Table. 16.3).. PAHs. are. present. in.
high. concentrations. in. coal. tars,. up. to. 70%-80%. by. weight.. Tar,. pitch,. and.
ash. once. spilt. or. deposited. in/on. the. grounds. persist. for. longer. periods,.
mostly. in. the. form. of. soil-polluted. PAHs.. The. puriier. waste. of. MGP. sites.
often. contains. signiicant. quantities. of. metals. like. cadmium,. lead,. arsenic,.
and.zinc.compounds..Inorganic.contamination.at.the.former.gasworks.sites.
usually. occurs. at. or. near. the. ground. surface.. Some. metals. can. leach. from.