[TT 17/7] La.i chuye^.n ddo^? cha^'t tha?i ra bie^?n DDo^ng

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La.i chuye^.n ddo^? cha^'t tha?i ra bie^?n DDo^ng

Kho^ng the^?, ne^'u Lua^.t mo^i tru+o+`ng co`n hie^.u lu+.c ! 

Mo.i vie^.c tu+o+?ng nhu+ dda~ ke^'t thu'c vo+'i y' kie^'n chi? dda.o
cu?a Thu? tu+o+'ng Vo~ Va(n Kie^.t, va`o tha'ng 2-1996, ve^` vie^.c
"kho^ng ddu+o+.c ddo^? ra so^ng, ra bie^?n VN ca'c loa.i cha^'t tha?i
kho^ng dda.t tie^u chua^?n cho phe'p", cu~ng nhu+ tra? lo+`i cu?a Bo^.
tru+o+?ng Bo^. Khoa ho.c - co^ng nghe^. & mo^i tru+o+`ng Pha.m Gia
Khie^m vo+'i dda.i bie^?u Quo^'c ho^.i cu?a ti?nh Ba` Ri.a - Vu~ng Ta`u:
"Bo^. kho^ng cho phe'p tie^'n ha`nh tie^'p tu.c thi' nghie^.m loa.i na`y
(ddo^? cha^'t tha?i sau le^n men ra bie^?n)". 

     The^' nhu+ng mo+'i dda^y, la.i co' y' kie^'n dde^` nghi. vo+'i Thu?
tu+o+'ng gia?i pha'p "cho Co^ng ty Vedan VN tie^'p tu.c thi' nghie^.m"
na`y. Trong khi ddo', ra^'t nhie^`u nha` khoa ho.c dda~ ba`y to? y'
kie^'n pha?n ddo^'i thi' nghie^.m tre^n vi` nhie^`u le~... 
     Nhie^`u na(m la`m vie^.c trong nu+o+'c va` o+? nu+o+'c ngoa`i trong
ca'c li~nh vu+.c vi sinh va^.t (VSV), di truye^`n pha^n tu+?, ngoa`i
ca'c kie^'n thu+'c co' ti'nh ly' thuye^'t ve^` qua' tri`nh pha^n hu?y
tu+. nhie^n ca'c phe^' lie^.u, to^i la` ngu+o+`i tru+.c tie^'p la`m
sa.ch mo^i tru+o+`ng ba(`ng co^ng nghe^. pha^n hu?y sinh ho.c. To^i dda~
trao ddo^?i vo+'i ca'c nha` khoa ho.c ve^` mo^i tru+o+`ng ta^`m co+~
quo^'c te^'. Vo+'i tra'ch nhie^.m va` lu+o+ng ta^m cu?a ngu+o+`i la`m
khoa ho.c luo^n quan ta^m dde^'n mo^i tru+o+`ng, to^i cho ra(`ng: kho^ng
the^? tie^'n ha`nh thi' nghie^.m ddo^? phe^' tha?i sau le^n men axit
glutamic ra bie^?n! 

Ly' do ve^` khoa ho.c
     - Phe^' tha?i sau le^n men chu+'a ra^'t nhie^`u cha^'t, song chu?
ye^'u la` hydratcarbon. Qua' tri`nh pha^n hu?y ho+.p cha^'t na`y kho^ng
the^? xa?y ra mo^.t - hai nga`y dde^'n sa?n pha^?m cuo^'i cu`ng kho^ng
ddo^.c. Ngay khi ca'c ho+.p cha^'t na`y ddu+o+.c xu+? ly' trong ca'c
bioreactor thi` vo+'i BOD va` COD cao nhu+ va^.y, tho+`i gian xu+? ly'
cu~ng pha?i ma^'t i't nha^'t hai tua^`n. Du` co' pha loa~ng do ho`a
vo+'i nu+o+'c bie^?n thi` ta^'t ca? ca'c cha^'t chu+'a trong phe^' tha?i
cu~ng pha?i tra?i qua qua' tri`nh pha^n hu?y sinh ho.c. 
- Khi ddo^? xuo^'ng bie^?n ma` la.i ddo^? ha(`ng nga`y thi` kha? na(ng
pha^n hu?y ra^'t ke'm. Vi` o+? mo^i tru+o+`ng bie^?n, nha^'t la` trong
ddie^`u kie^.n ky. khi' hoa(.c thie^'u oxy, nhie^.t ddo^. o+? dda'y
bie^?n la.i tha^'p, lu+o+.ng nito+ va` pho^tpho cung ca^'p cho VSV ra^'t
tha^'p, ne^n VSV kho^ng the^? pha't trie^?n dde^'n ddu? so^' lu+o+.ng
dde^? co' the^? pha^n hu?y gio^'ng nhu+ trong ca'c bioreactor ma` mo.i
qua' tri`nh sinh ly' sinh ho'a cu?a VSV co' the^? ddie^`u khie^?n
ddu+o+.c. DDo' la` chu+a no'i dde^'n so^' lu+o+.ng VSV tham gia va`o
qua' tri`nh pha^n hu?y na`y nghe`o ho+n so^' lu+o+.ng VSV la`m nhie^.m
vu. tu+o+ng tu+. o+? mo^i tru+o+`ng dda^'t va` nu+o+'c ngo.t dde^'n
1.000 - 10.000 la^`n. Lie^.u co' kha? na(ng cho nito+ va`  pho^tpho o+?
da.ng pha^n bo'n ma` VSV co' the^? su+? du.ng dde^? nha^n le^n ta.i mo^i
tru+o+`ng bie^?n ddu+o+.c kho^ng? Cha('c cha('n la` kho^ng the^?! 
     - Ne^'u xe't dde^'n co+ che^' va` ca'c sa?n pha^?m ta.o ra sau qua'
tri`nh pha^n hu?y phe^' tha?i sau le^n men mi` chi'nh (bo^.t ngo.t),
thi` vie^.c ddo^? ra bie^?n la.i ca`ng kho^ng the^? ddu+o+.c. Sau qua'
tri`nh pha^n hu?y ky. khi' ra^'t cha^.m cha.p, se~ co' ca'c sa?n pha^?m
nhu+ ca'c axit hu+~u co+, CH4, CO2... Trong mo^i tru+o+`ng bie^?n la.i
co' ra^'t sa(~n SO42-, qua' tri`nh khu+? sulphat hoa`n toa`n va` kho^ng
hoa`n toa`n (nguo^`n cho ddie^.n tu+? la` acetat va` lactat), se~ ta.o
ra mo^.t lu+o+.ng H2S kho^ng nho?. Ta^'t ca? dda'y bie^?n no+i ddo^?
phe^' tha?i se~ co' ma`u dden do FeS hay cu?a kim loa.i kha'c va` bu`n
ho^i tho^'i se~ kho^ng the^? na`o loa.i bo? kho?i dda'y bie^?n. Vo+'i
no^`ng ddo^. 10mg/l H2S dda~ ha.i dde^'n sinh va^.t. Co+ che^' ga^y
ddo^.c na`y la` sulphuahydro la`m du+`ng qua' tri`nh pha^n chia te^'
ba`o, ne^'u no^`ng ddo^. cao ho+n ca^y se~ tho^'i vi` bo^. re^~ ca^y bi.
pha' hu?y dda^`u tie^n. 
     Co`n qua' tri`nh bie^'n tha`nh tra^`m ti'ch thi` kho^ng ddo+n gia?n
nhu+ chu'ng ta hie^?u, pha?i ca^`n dde^'n ha`ng trie^.u na(m ma` pha?i
co' ye^'u to^' nhie^.t ddo^. va` a'p sua^'t thay ddo^?i di. thu+o+`ng. 

Xe't ve^` khi'a ca.nh lua^.t pha'p va` dda^`u tu+
     To^i chu+a ddu+o+.c bie^'t va` chu+a ddu+o+.c ddo.c lua^.t cu?a
ba^'t cu+' nu+o+'c na`o co' mo^i tru+o+`ng sa.ch la.i cho ddo^? phe^'
tha?i ra bie^?n. Vedan kho^ng the^? ddo^? phe^' tha?i cu?a ho. ra bie^?n
ne^'u nha` ma'y na(`m o+? DDa`i Loan hay ba^'t cu+' nu+o+'c na`o ma`
Lua^.t mo^i tru+o+`ng co' hie^.u lu+.c. Ne^'u ai cu~ng mang ddo^? mo.i
thu+' phe^' tha?i ra bie^?n ma` kho^ng ca^`n xu+? ly', thi` bie^?n ca?
se~ cha(?ng co`n co' the^? thu+.c hie^.n ca'c chu+'c na(ng nhu+ hie^.n
nay ve^` ma(.t khi' ha^.u. Ha^.u qua? cu?a qua' tri`nh tha?i bu+`a ba~i
cha('c cha('n da^~n dde^'n thu+.c va^.t, ddo^.ng va^.t va` ca'c VSV se~
kho^ng co`n, do sinh tha'i thay ddo^?i theo chie^`u hu+o+'ng xa^'u. Ca'c
vu`ng chi.u cha^'t tha?i ddo^? xuo^'ng se~ hoa`n toa`n bi. pha' hu?y. Xu
the^' cu?a tho+`i dda.i hie^.n nay la` la^.p ke^' hoa.ch khai tha'c
be^`n vu+~ng nguo^`n ta`i nguye^n thie^n nhie^n cu?a bie^?n. 
     Ta.i sao Vedan kho^ng la`m nhu+ ca'c ddo+n vi. kha'c, dda^`u tu+
xu+? ly' phe^' tha?i va` sa?n pha^?m xu+? ly' phe^' tha?i la.i ddu+o+.c
du`ng la`m pha^n bo'n? 
     Mo^.t ddie^`u dda(.t ra tru+o+'c ma('t chu'ng ta la`: ca'c co^ng ty
nu+o+'c ngoa`i thu lo+.i nhua^.n va` sau ddo' ho. ve^` nu+o+'c, co`n
ngu+o+`i VN la.i pha?i chi.u thie^.t ha.i. Ma` thie^.t ha.i do mo^i
tru+o+`ng bie^?n bi. suy thoa'i thi` kho^ng the^? ddong dde^'m chi'nh
xa'c va` lu+o+`ng tru+o+'c ddu+o+.c.

TS DDa(ng Thi. Ca^?m Ha` 
(Vie^.n Co^ng nghe^. sinh ho.c, 
Trung ta^m Khoa ho.c tu+. nhie^n 
va` co^ng nghe^. quo^'c gia)