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<br /> Biorcmcdiatiar�: The
<br /> Dy: Alex Vim, Project 7Yeatrr�erat For Tough Chlorinated Hydraaarb
<br /> Scientist and Sam Fogel, PhD, Director, Bioremterns ediation S S ons
<br /> W.
<br /> 1
<br /> Chlorinated hydrocarbons Glossary Gt y1 .�'�'
<br /> —PCE, TCE, DCE, VC--rani: could be dcgr another
<br /> high an anyanc•s list of danger- PCE Te(rachloroechylene specia3 m#crobiat process
<br /> ous pollutants because most or Rarchloroethyiene Anaerobic bacteria (bacteria
<br /> arc cutter suspected or known TCE TrichtOroethylene which grow in the absence of
<br /> carcinogens. Unfortunaccly, DCE Dichloroethylene oxygcnj were shown tp cruns.
<br /> they arc very persistent in VC Vinyl Chloride form PCE to a mixture of TCE,
<br /> • groundwater and slow to DCE, and VC. The proccss is
<br /> degrade under natural condi- water trcatment processes and [crmcd "reductive dehalogen-
<br /> tions. Since chlorinated hydro- pz55 through activated sludge ation:' The progressive pa[h
<br /> carbons are v or trickling tjl(er planes into of this conveys#on is shown in
<br /> otari2e chemicals,
<br /> � sir • air stripping is frequently used grounwr
<br /> datcand chc air. This Figure t•
<br /> r , atment. But, air strip- is due, in part, to the chlorinc Tm
<br /> The problem, as giverl in the
<br /> --, • ., as a tre
<br /> ping relea_scs the chemicals part of the nolecu 'which hich landU example, is that ti-c
<br /> . . •• into the atmosphere.'inch ccncis to shield the carbon can4R?-Q rccondicion5 dorninate.
<br /> • rccenc(y, the only other treat- atoms froth traumatic arcack. The reductive dechlorination
<br /> t [n addition, chlorinated hydrtransformation o- tnsformation process does
<br /> • .-, rncnt has been carbon adsorp_ carbons don't dissolve well in not mineralizc the PCE but
<br /> ' cion which is extremely water where bacteria arc most gene[-aces an e•ren more hazard.
<br /> Bioremediation is eme3in3 errccttve. ous product, vinvl chloride.
<br /> as an el ective and economical 0"
<br /> the la most common T:• m
<br /> O speciaJ biocheical"
<br /> "1 answer to the difhcutc problems tiolattle organic comoounds processes have been shown xo
<br /> „ posed by chlorinated hydro-
<br /> . Z4 ,r dccec[ed in drin_king water suo- degrade chlorinaccd solvcn s•
<br /> ` carbons_ Bioremediation is pUes, 10 are'`012CUC tw•o-carbon ; but c2ch proccss is incomolece
<br /> based, in-part, on a naturai#v• con'Potinds. Their presence in ; when taken alonc, So why hoc
<br /> • •+ chc water supply is of concern GI them? The firsr proc-
<br /> . ,... ��
<br /> occurring process. For exam- because of the toxiciry and sus_ ; ess invoives the anaero brc bac
<br /> Plc. tetrachloroethylene(PCe), petted carcinogensciry of the 1 tcria(known as rrsectr na a tris
<br /> dumped in a landfill, wilt etien comoounds. !n ltassachusetcs ttFst trarsiorm PCE 10TC:etc.
<br /> tually become a mixture of
<br /> TCE, DCE and V afonc, 2' out at Fhe 45 corn- s
<br /> The second process nvolvcs
<br /> C over t#me. municies chat havc retired
<br /> �• Left to nature, the oroCess rnav c i methane-tttiEzing bacteria
<br /> "accsuoaly w cls from (known an
<br /> s methanotroos)
<br /> Fake a decade or more, but the t fisndarn�ntal observation -service eice due eo g.roundwater that comc)icre the destruction.
<br /> V� is
<br /> instructivecontamirFation did so duc to The sc organisms, which arc
<br /> v! - 3iotransfor-rnation conLIM�narion by chlorinarrd ecologically linked in the ?and-
<br /> is taking f
<br /> C' C• g p ace_ �lacut-a-lav hydrocsrbons. ;�,
<br /> C-C Occurring bacteria arc at work .yr� fill CUinplc, a150 share affinity!and-
<br /> C; metabolizing the tetrlchta- hlonnated two foe chc sarnc class of hazordous
<br /> �C rCE roc[hytcnc—even under the Compounds wc;e once con- compounds. A trcarmcnc proc-
<br /> sidcrcd non-biodegradable. css based on this microbial
<br /> anaerobic conditions that are Howe-tr, in 1986, ABS Envi- model requires chc two groups f
<br /> i typical, not only for'chc land- ronmcrtud Services reported of bacteria be brought [ogeFher
<br /> C=C FF#1, but is basic
<br /> c waciDt well. the complete mineralization in the proper transforming
<br /> H Once this bas ie concept is '(conversion CO C:Lrbon dioxide' �aucnce. .�
<br /> vc accepted, chc possibW'ry of
<br /> H creating an effec-Live(and fir , or trichloroe h'rlc [c(TCE) in
<br /> =Hz faster) means of biodc mdin the presence of CI�r7727rC, WO-Zone Plume Interceptiom
<br /> g S ,methane-utiLLz ng bactcria Treatment Technology
<br /> vvlarile chlorinatcd aliphatic '(hacccna which obtain carbon o- ane umc-
<br /> 7e reductive dehal4genation hydrocirbons, such as PCE,
<br /> TCE and DCE becomes from methane acrd require oxxv� Interception Treatment is
<br /> hydrogen replaces thio �ecnj. SubSCQUcntJY, tetany other designed for the in-situ treat,
<br /> alta;rng;he Canoe ��
<br /> sif d r'sr4n to Pt�CLiCai, ,
<br /> y egraded compounds T bcse Chemicals have C'Nor-in3ccci'so(vencs weic also Ment of groundwater contain-
<br /> become widely distributed in Shown to be sirritlarly biodc- X09 rnultit)le concaminartt_s.
<br /> the environment as s rrsulr of gradable, but not;all. Hiphty e proccss is the pracdcal
<br /> industrial discharges and spins chlorinated compounds such appiicacion of chc anaerobic
<br /> dirccdy into surf�cc %raters and as PCE went not destroyed by mducrive dchalogenarion r_oe
<br /> groundwacers. Chlorinated sol- this Process. css foflowed by the aerobic
<br /> vents resist dcgr dation by Other res=rchcn, including trcarmcnt of the products.
<br />' torrverrciancrl biological, wa.src `S`B$scic:ttists,rdemonstraced --�-�'
<br /> in the labotar0 rhac PCE Continued on page 4
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