phẦn ii vsv vÀ cÁc quÁ trÌnh sinh hỌc trong …moitruong.com.vn/upload/48/nam_2013/thu vien...

L Xun Phng VI SINH VT HC MI TRNG

195

PHN II VSV V CC QU TRNH SINH HC

TRONG CNG NGH MI TRNG

CHNG VI

C S SINH HC CA QU TRNH X L NHIM MI TRNG

6.1 TNH HNH NHIM MI TRNG HIN NAY

6.1.1 nhim do nc thi sinh hot Nc ta c nn kinh t cha pht trin, h tng c s cn cha c pht trin

theo mt quy hoch khoa hc, h thng t lm sch ca knh rch, sng ngi b hu hoi nn nc thi sinh hot gy nhim nghim trng. Ch ring thnh ph H Ch Minh vi khong 3,95 triu dn ni thnh hng ngy thi ra mi trng khong 350.000 m3 nc thi sinh hot. Nc thi sinyh hot ny c thnh phn gy nhim cao hn tiu chun rt nhiu. Theo kt qu phn tch, ta c mt s liu trung bnh nh sau :

PH : 6,5 - 7,2 BOD : 98 - 260 mg/l COD : 146 - 447 mg/l Cn l lng > 100 mg/l Nc thi phn ln cha c x l trc khi vo knh. Phn tch mu nc

ti knh Tn Ho cho thy : PH : 4,7 - 6,8 BOD : 140 - 204 mg/l COD : 129 - 4241 mg/l SS : 91 - 662 mg/l E.coli : 6 - 14.000 tb/l 6.1.2 nhim do nc thi cng nghip Nc thi cng nghip c cha nhiu kim loi nng, cc cht mu du m, cc

cht hu c. S gy ra nhim bn mi trng do nc thi cng nghip phc tp hn nc thi sinh hot rt nhiu. V th vic x l chng gp khng t kh khn. Phn ln cc nh my x nghip khng qua x l s b m thi nc thi trc tip xung cc


196

knh rch gy nn tnh trng hi thi, lm bin mu nc, lm cht cc thu sn, lm kh nng t lm sch ca knh rch gim r rt, c ni khng th t lm sch c ...

6.1.3 nhim do rc thi : Mi trng khng ch b nhim bi nc thi sinh hot v nc thi cng

nghip, mi trng cn b nhim bi nhiu ngun khc. Trong ng quan tm nht l rc sinh hot. Phn ln cc thnh ph Vit Nam chua c mt cng ngh hon chnh x l rc thi sinh hot. Do vic nhim do rc thi cng ngy cng tr nn trm trng. Ch ring thnh ph H Ch Minh mi ngy thi ra mi trng 3.500 tn rc, s rc ny lun l ngun gy ra bao nhiu phin toi cho cuc sng. Rc sinh hot ca chng ta chim > 60% l rc hu c. V th sinh vt gy bnh pht trin rt mnh. 6.2 NGUYN L C BN CA CC QU TRNH

6.2.1 X l sinh hc nc thi Nu khng b nh hng nghim trng bi cc cht c hi trong nc thi, cc

knh rch ao, h c kh nng t lm sch nh hot ng sng ca vi sinh vt. Cc qu trnh c bn xy ra theo phn ng sau :

Vi sinh vt

Cht hu c + O2 + NH3 Sinh khi + CO2 + H2O Phn hu Vinh sinh vt Cht hu c + O2 ng ho Hin nay c hai phng php x l nc thi bng cng ngh sinh hc : hiu kh

v ym kh 6.2.2 X l nc thi trong iu kin hiu kh Qu trnh phn gii cc cht hu c trong iu kin hiu kh c th tm tt nh sau: Vi khun

Cht hu c + O2 CO2 + H2O + Sinh khi vi khun Cc cht dinh dng Hoc l : Vi khun Cc sn phm Cc sn Cht hu c + O2 xy ho + phm tng Cc cht hp dinh dng

Nng lng t do


197

Theo Eckenfekler W.W v Connon D.J th qu trnh phn hu cc cht hu c trong iu kin hiu kh c thc hin bi phn ng sau :

1. xy ho cc cht hu c

CxHyOz + O2 CO2 + H2O + AH 2. Tng hp xy dng t bo

CxHyOz + O2 Sinh khi vi khun + CO2 + H2O +

C5H7NO2 - H 3. xy ho cht liu t bo (t xy ho) T bo vi khun

C5H7NO2 CO2 + H2O + NH3 H

H nng lng c thi ra hoc hp th vo iu kin thc hin qu trnh x l sinh hc: m bo lin tc cung cp xy Lng cc nguyn t dinh dng cn thit cho qu trnh sinh ho xy ra trong

qu trnh ln men. Nng cc cht hu c cho php qu trnh ln men. Nng cho php ca cc cht c hi pH thch hp Nhit nc thi trong khong hot ng ca vi sinh vt.

Tham gia trong qu trnh phn gii cc cht hu c trong nc thi gm 3 nhm vi sinh vt.

- Nhm vi sinh vt phn hu cc hp cht mch h, ru, aldehyt axeton, cc axit. - Nhm vi sinh vt tham gia phn hu cc hp cht thm: benzen, Phol, Toluen,

Xilen. - Nhm cc vi sinh vt xy ho dy polimetyl (hydrocacbon du la) paralin. Ngoi lng vi sinh vt c sn trong cc ngun nc thi, ngi ta cn cung cp

thm cc loi vi sinh vt c chn lc k theo cc dng ging sau: * Bn hot tnh. Loi bn tham gia x l t nhin cc knh rch, ao, h.

Loi bn ny c hot ho vi sinh vt trc khi a vo s dng. * Nhn ging vi sinh vt ring dng lng v cho thm vo thit b x l hoc

h x l theo mt t l nht nh. * Nhn ging vi sinh vt ring dng bt kh v cho thm vo thit b x l hoc

h x l theo mt t l nht nh.

Enzym

Enzym

Enzym


198

* Gn vi sinh vt trn mt cht mang no (Phng php c nh t bo) v x l lin tc.

6.2.3 X l trong iu kin ym kh Trong iu kin ym kh vi sinh vt phn gii cc hp cht hu c qua 2 giai

on: * Giai on thu phn cc cht hu c s b thu phn di tc dng ca cc

enzym vi sinh vt. Sn phm cui cng ca qu trnh s l cc cht kh ch yu l CO2 v CH4. Giai on ny ngi ta gi l giai on to kh.

Theo Eckenfelder qu trnh ln men ym kh cht thi c chia lm 3 giai on. * Giai on ln men axit. Nhng hydrat cacbon (ng, tinh bt, cht x) d b

phn hu v to thnh cc axit hu c (axit axetic, axit butyric propionic) pH gim xung < 5 c km mi thi.

* Giai on chm dt ln men axit cc cht hu c tip tc c phn gii to thnh cc cht kh khc nhau nh CO2, N2, CH4, H2 ... pH ca mi trng dn dn tng ln. Mi thi ra rt kh chu do thnh phn ca H2S, indol, scatol, v mecaptan. Bn c mu en, nht, v to bi ni ln trn b mt.

* Giai on ln men kim Hay giai on ln men metan. Cc sn phm trung gian, ch yu l xelluloza, axit bo, cc hp cht cha nit tip tc b phn hu v to rt nhiu kh CO2, CH4, pH mi trng tip tc tng ln v chuyn sang dng kim.

6.2.4 X l rc sinh hot: Rc sinh hot cha trn 60% l rc hu c. m rc v ma nng l 45 - 60%,

ma ma c th trn 80%. m cao lm pht sinh nhiu vi sinh vt. Rc sau khi c loi b cc thnh phn khng hu c s c ln men. Hin nay c ba phng php x l rc bng vi sinh vt.

- Phng php chn rc: Rc c thu gom li ri em chn xung t. trnh rui, mui, cn trng ngi ta ph ln rc mt lp dy 30 - 50 cm dt, hoc than bn hoc ct. Thng dng than bn c hiu qu tt hn v than bn c kh nng hp th mi. Qu trnh ny (composting) ko di hng nm tri. Di tc dng ca vi sinh vt cc cht xenluloza, lingin, hemixelluloza b phn hu to thnh mn. Nhit khi tng dn c khi t ti 75%. Sau thi gian ngi ta ly ra sng lm phn bn.

- Phng php c o trn: Phng php ny da trn s hot ng mnh ca cc loi vi sinh vt hiu kh. Thng ngi ta cho rc vo cc thng quay. Thng quay ny gi l cc thng sinh ho. C s xo trn thng xuyn ca h thng quay v thi khng kh lin tc vo. Thi gian phn hu rc rt nhanh. Nhit trong thng quay thng cao hn 65oC. Sau mt hti gian khong 24 gi = 48 gi quay lin tc, rc c phn hu cha hon ton. Sau rc c m ra phn loi v thnh tng ng ngoi tri, ln men t nhin cho n mc ht v em lm phn bn. u im ca phng php ny l nhanh, d t ng v c gii ho.

- Phng php th cng c o trn: Phng php ny c ci tin trn c s phng php c truyn ca dn. Trong phng php ny c cung cp ging vi sinh vt ging lm rc chng phn hu hn. Cc ging vi sinh vt thng s dng l cc loi


199

nm mc, Bacillus v x khun. u im ca phng php ny l d thc hin v c th ph bin cho nng dn thc hin i tr c. 6.3 MT S LOI VI SINH VT S DNG TRONG X L NHIM MI TRNG

Hin nay, Vit Nam trong cng tc x l cht thi tn ti v c s dng ph bin mt s chng loi vi sinh vt hu hiu nh : vi sinh vt phn gii xenluloza, protein, lignin, tinh bt ... C th c cc loi chnh l :

1. Vi sinh vt hu hiu EM : c ngun gc t Nht Bn do Trung tm chuyn giao Cng ngh Vit - Nht, B Khoa hc, Cng ngh a vo th nghim Vit Nam.

2. Vi sinh vt Emuni v vi sinh vt xenluloza: l ch phm ca Trung tm ng dng Vi sinh vt thuc i hc Quc gia H Ni.

3. Vi sinh vt Micromic 3: l chng loi vi sinh vt ca Vin Cng ngh Sinh hc, Trung tm Khoa hc T nhin v Cng ngh Quc gia.

4. Chng loi vi sinh vt ca Trung tm ng dng Vi sinh vt thuc Trng i hc Quc gia H Ni.

6.3.1 Ch phm vi sinh vt hu hiu EM : 6.3.1.1 c tnh k thut ca EM: Em s cp (EM gc) l dung dch c mu nu vi mi d chu, c v ngt chua,

pH ca EM t mc di 3,5. Nu c mi nng hoc thi th pH > 4, khi EM gc b hng khng s dng c. EM gc l vi sinh vt khng hot ng. V vy, EM gc cn hot ng bng cch cung cp nc v thc n, bng cch thm nc v r ng. S dng dung dch EM pha long gi l EMtc, x l mi trng, phun cho cy trng, vt nui.

Bokashi l mt dng ca EM trng thi bt, y l cht hu c ln men v tng t nh phn trn compost. Nhng n c chun b bng cch ln men cht hu c EM. N c th s dng c t ngy th 3 n ngy th 14. Sau khi ln men Bokashi c th dng cho sn xut, cy trng, thm ch cho c cht hu c cha b phn hu trong thnh phn phn trn. Khi Bokashi bn vo t, cht hu c c th s dng nh l thc n cho vi sinh vt v c tc dng lm tng lng vi sinh vt hu hiu trong t cng nh nui dng cy trng. Bokashi c phn nhm thnh Bokashi a kh v k kh theo cc quy tnh sn xut.

6.3.1.2 Cc vi sinh vt chnh trong EM a. Vi khun quang hp b. Vi khun axit lactic c. Cc men. d. X khun e. Nm men


200

Mi loi vi sinh vt trn c chc nng quan trng ring. Tuy nhin, vi khun quang hp l xng sng hot ng ca EM v n h tr hot ng ca cc vi sinh vt khc.

6.3.1.3 Cch s dng : Ta c th s dng EM bng bn cch (EM1, EM Bokashi, dung dch EM5 v dch

chit cy ln men). a. Dung dch EM1 c th s dng bng cch: - Ti vo trong t, phun ln l. b. EM Bokashi: l cht hu c ln men, n c iu ch bng cch ln men cc

cht hu c (cm go, bnh du, bt c...) vi EM Bokashi c iu ch dng bt v l cht b sung quan trng tng vi sinh vt hu hiu trong t.

c. EM5 l hn hp ln men ca gim, ru (cn), r ng v EM1. N c s dng phun ln cy nhm ngn chn gy bnh v chng su hi xm nhp.

d. Dch cy ln men EM: Chit xut cy ln men l hn hp ca c ti c ln men vi r ng v EM1. N cung cp dinh dng v nh lng cho cy trng v ngn chn su bnh ph hoi.

* EM1 Cch s dng EM1 : EM1 (gc) l vi sinh vt khng hot ng. V vy, EM1 cn

c hot ng bng cch cung cp nc v r ng (l thc n ca EM). Dung dch EM pha long 0,1% dng phun cho cy trng:

- 1000 ml nc. - 1 ml ca EM1 - 1 ml r ng hoc 1g ng bt k Dung dch ny trong vng 24 gi ri phun cho cy, t hoc cht hu c. * Bokashi : - Bokashi c nhiu dng, n ph thuc vo cht hu c s dng. Bao gm: Cm

go : 100 lt, Bnh du : 25 lt (hoc v tru), Bt c (phn g) : 25 lt, EM1 : 150 ml, Ri ng : 150 ml, Nc : 15 lt

- m Bokashi cn t 30 - 40%. Qu trnh ln men t 3 - 4 ngy (ma h) v t 7 - 8 ngy (ma ng) vi nhit trung bnh 35 - 45oC.

Cch s dng Bokashi: 200 gam Bokashi cho 1m2 trn b mt ca t (rc) khi c cht hu c. C th s dng ti a 1kg/1 m2 khi t ngho v c t cht hu c.

* EM5 : L cht xua ui cn trng, khng c hi v n c tc dng chng bnh su hi cy trng. Thng thng n c phun ln cy vi nng 1/500 - 1/1000 trong nc.

6.3.1.4 ng dng EM 1. ng dng trong x l ph thi


201

- Ti dung dch Emtc pha long 1/1000 phun vo rc cha phn loi. - Rc sau khi phn loi lng vo b 150 m3 tip tc phun EM o trn

m bo m 40 - 50%. - a vo b ho kh thi gi ch 2h/ngy (8%) 2. ng dng trong nng nghip Kh nng s dng EM trong nng nghip ch yu l cy trng. S dng EM1 + EM5 cho cy trng nh bng 6.3.1 Bng 6.3.1

Loi cy Cch s dng c th

Vi thiu ang kt tri Phun 1/2 cy cn li ang i chng

Cam, qut, bi Qu ang non phun ln mt s cy

Nho Phun 1/2 cy dn trn cc chm qu xanh

u Phun ln 2 cy trong s 3 cy

Roi Phun ln mt s chm qu

Hng Thch Tht Phun ln 1/2 cy

Rau ngt, rau ti Phun ln 1/2 din tch

Rau mung Phun 50m2

Ray ay Phun 10 m2

Thi gian theo di cha di song theo bo co ca nhng ngi trc tip tin

hnh th nghim c mt vi nhn xt sau : - Vi thiu l cy mu xanh m, qu chn sm hn, v bng p hn so vi i chng. - Cam, qut, bi: l pht trin tt hn, qu ln nhanh hn. - u : l xanh m, qu pht trin nhanh hn i chng. - Nho, roi : qu chn u v sm hn, nng sut tng 10% - Cc loi rau : l c mu xanh m hn, dy, to ln v cho thu hoch sm hn t

3 - 4 ngy, nng sut tng khon t 15 - 20%. Rc Bokashi x l chung li, chung g, ging nc b thi. Kt qu cc

chung tri ht mi sau 3 ln rc Bokashi vi lng rc 100g/m2. Mt ng cng b thi c x l bng Bokashi nay sch mi.

Bokashi trong chn nui : my ngy u cha quen, sau n mnh v chng ln. 6.3.2 Ch phm emuni, ch phm phn gii xenluloza Cc chng loi vi sinh vt ca Trung tm ng dng Vi sinh vt thuc i hc

Quc gia H Ni.


202

6.3.2.1 Ch phm vi sinh vt Emuni - Cc vi sinh vt c kh nng phn gii Xenluloza nh vi khun Bacillus SP,

Cellulomonas sp, x khun Streptomyces, Nm si Aspergillus japonicus. A.oryzae. - Cc vi sinh vt c kh nng phn gii tinh bt, protein nh nm men

Saccharomyces cerevisiae. - Vi khun Azotobacter sp c kh nng c nh nit kh quyn, vi khun sinh

cht kch thch cho s tng trng ca thc vt. - Vi khun Pseudomonas SP c kh nng chuyn ho ln kh tan thnh d tan, vi

khun sinh cht khng sinh Bacterioxin. Tc dng : - X l ph thi nng nghip lm phn hu c vi sinh. - Phn gii nhanh rc thi, phn bc, phn chung, gim thiu ti a mi hi thi,

hn ch rui mui, dit nhiu mm bnh v trng giun. - Chng ch tc b pht. - Bn phn hu c sn xut t ch phm Emuni s lm cho t ti xp, tng

ph nhiu, gi nc, tng kh nng chng chu su bnh, nng cao nng sut v cht lng sn phm cy trng.

Cch s dng : - Dng kh mi h x, chung tri chn nui, gia sc, gia cm : 100 g ch phm

cho vo 40 lt nc, phun ti u chung tri (1 ln trong mt tun). - Dng x l mi trng t rc thi : 100g ch phm ho vo 100 lt nc phun

vo rc, ng. - Dng x l h x b phn, b pht: 100 g ph phm trn u vi 2 lt nc

phun vo h x cui ngy (t 1 - 1,5m3) dng hai thng mt ln. - Dng phn hu c : 100 g ch phm cho 1 tn phn rc c m 45%, c

th b sung thm phn gia sc hoc than bn, che y k trnh mt nhit. Sau mt n hai tun c th o trn, khong 20 ngy phn hoai l c th dng c.

6.3.2.2 Ch phm vi sinh vt xenluloza Ch phm ny c phn lp t cc mu t cc tnh pha Bc. Cc chng vi

sinh vt c nui cy trn cc ngun xenluloza t nhin nh b ma, cm tru, mn ca, v lc, rm, v c ph vi m 50%, n c hot tnh mng trn v c ph vi m 50%, n c hot tnh mnh trn v lc, rm, cm tru, yu nht ph thi t ngun c ph.

Cch s dng : - Dng kh h x, chung tri chn nui gia sc gia cm : 100g ch phm cho

vo 40 lt nc phun ti u ln chung tri (1 ln trong mt tun). - Dng x l mi trng t rc thi: 100 g ch phm ho vo 100 lt nc phun

vo rc (ng ).


203

- Dng x l h x, b phn, b pht 100g ch phm trn u vi 2 lt nc phun vo h x cui ngy (vi dung tch b t 1 - 1,5 m3) dng 2 thng mt ln.

- Dng phn hu c : 100g ch phm cho 1 tn rc vi m t 45% c b sung thm phn ca gia sc hoc than bn (sau che y kn) trnh mt nhit. Sau t mt n hai tun ta o trn, khong 20 ngy sau phn loi c th dng .

Sn phm cui cng ca qu trnh x l ph thi hu c cha xenluloza l phn hu c. Phn hu c c xc nh thnh phn ho hc.

Bng 6.3.2 Cc thnh phn ho hc trong cc loi phn

Loi phn Mc N,% P2O5,% K2O,% Ti a 0,358 0,250 1,60

Ti thiu 0,246 0,115 1,129 Tru Trung bnh 0,306 0,171 1,360

Ti a 0,380 0,294 0,902 Ti thiu 0,302 0,164 0,924 B

Trung bnh 0,341 0,227 0,958 Ti a 0,861 1,958 1,412

Ti thiu 0,537 0,932 0,954 Ln Trung bnh 0,669 1,253 1,194

Ti a 0,973 0,800 0,612 Ti thiu 0,450 0,450 0,350 Phn rc

Trung bnh 0,740 0,625 0,481 Ti a 0,550 0,614 0,350

Ti thiu 0,250 0,350 0,150 Phn than bn v b bn Trung bnh 0,450 0,482 0,250 Trong thnh phn ho hc phn hu c ch bin t ph thi hu c thy c

cc yu t vi lng. S lng nguyn t vi lng c trnh by bng 6.3.2 6.3.3 Vi sinh vt micromix 3 L tp hp cc chng vi vt hiu kh v a nhit c kh nng phn gii xenluloza

mch b sung vo b x l rc thi, nhm phn hu nhanh cht thi hu c, rt ngn thi gian phn hu v nng cao hiu sut s dng b x l. Vi sinh vt c nghin cu v a ra quy trnh sn xut ch phm ti phng Nghin cu cc Cht hot tnh Sinh hc t Vi sinh vt do Vin Cng ngh Sinh hc, Trung tm Khoa hc t nhin v Cng ngh Quc gia nghin cu.

6.3.3.1 Thnh phn ca vi sinh vt Micromix 3 Cc

nguyn t AI Si Mg Ca Sr Fe V Mn Ba Ti

Cc thnh phn, % 10 >10 0,5 10 0,01 5 0,002 0,05 0,01 0,5

Cc nguyn t Ni Cr Mo Sn Cu Pb Ga Zn Na Ag


204

Cc thnh phn % 0,01 0,01 0,0005 0,02 0,02 0,02 0,01 0,02 0,5 0,0001

1. Tuyn chn cc chng a nhit tng hp xenlulaza S lng chng c hot tnh xenlulaza ca cc nhm vi sinh vt cao phn lp

c t b rc cao; vi khun 40%, x khun 90% v nm mc 36,37%. Cc chng x khun phn lp phn theo nhm mu cho thy nhm xm

(GY) l cao nht chim 67,5%, sau d l nhm - 23,75% v nhm trng (W) - 8,75%. Khng thy xut hin cc chng thuc nhm lc (Gn), xanh da tri (B) v tn (V).

Kh nng phn gii CMC - Na v bt thy ca cc chng vi sinh vt cng khc nhau (bng 6.4).

Bng 6.4 T l cc chng vi sinh vt c hot tnh xenlulaza (nui 45oC)

Hot tnh Cx(%) Hot tnh C1,(%) Tng s chng c hot tnh xenlulaza Yu Mnh Yu Mnh

140 43,02 56,98 66,1 33,9

Ghi ch : yu : (D-d) < 20 mm; mnh (D - d) > 20 mm tuyn chn cc vi sinh vt a nhit c kh nng sinh tng hp xenlulaza

mnh, cc chng thun khit c nui trn mi trng c bt xenlulaza v CMD 50oC. Trong s 40 chng c hot tnh xenlulaza chn dc 12 chng x khun (k uhiu C1, C3, CD30, CD31, CD6,2, CD6,9 , CD6,10, N24, N43, CD99, CD108, CD5,12) v tm chng vi khun (k hiu CD-1, CD-2, CD-3, CD-4, CD-14, CD45 v C5) c hot tnh xenlulaza (c C1 v Cx) mnh tip tc nghin cu.

2. c im sinh hc v c im phn loi ca cc chng vi sinh vt tuyn chn

a. Vi khun : Kt qu phn loi : T kt qu th nghim cc chng vi sinh vt vi b KIT API

50 CHB i vi vi khun Gram dng, cc c im hnh thi t bo, tnh cht nui cy so snh vi im phn loi cc chng Bergey cho thy : cc chng : CD-1, CD-3, v CD-14 ging loi Bacillus stearothermophylus, Donk (1920) 373 A1 ATCC 12980 : CD-2, CD4, CD-9 ging loi Bacillus polymyxa, Prazmowski (1880), Mac (1889), 588 A1 ATCC 842. Nh vy, tt c cc chng vi khun Gram dng tuyn chn c u thuc chi Bacillus ring chng C5 thuc nhm vi khun Gram m. Chng C5 thuc nhm vi khun Gram m. Chng ny c cc c im pha loi gingchi pseudomonas, nhng cha nh tn loi.

b. X khun: Kt qu phn loi: Cc chng x khun tuyn chn c u thuc chi

Streptomyces (Waksman v Henryci, 1943). Da vo kho phn loi x khun ca Nnmura v so sh vi cc phn m t c im phn loi ging cc loi sau :


205

- Cc chng C3, C69, v N43 ging loi Streptomyces thermoflavus (Kudrima v Makximova) Pridham 1970 ISP 5252.

- Chng CD-30 ging loi S.flavoviridis krasilnikov, 1941 ISP 5153

- Cng CD-31 ging loi S.pulcher Rao, Renn v Marsh 1967 ISP 5566

- Chng CD-62 ging loi S,tendae, Ettlinger et al, 1958 ISP 5101

- Chng CD-512 ging loi S.seleroliolus thirumalchar ISP 5269

- Chng CD-108 ging loi S.flarovirens, Pridham 1958 ISP 5152

- Chng N24 ging loi S.gedanensis, Waksman 1953 ISP 5518 - Chung CD-99 c hnh dng, cu trc cun sinh bo t dng chm khng ging

loi no c m t, v hu ht cc loi tuc nhm ny nu cung sinh bo t xon chm th bo t ca chng c cu trc nhn. Do vy, tm tn chng ny l Streptoverticillium SP. CD-99.

6.3.3.2 Nghin cu quy trnh sn xut ch phm Micromix 3 T cc kt qu nghin cu c im sinh hc, cc yu t nh hng ln sinh

trng v sinh hc tng hp xenlulaza v kh nng phn gii xenlulaza ca hn hp cc chng vi khun v x khun cho thy: c th s dng cc chng tuyn chn nhn ging sn xut ch phm vi sinh vt a nhit b sung vo b x l rc thi hiu kh. Ch phm Micromix 3 c sn xut t hn hp cc chng:

Vi khun : CD4, CD-2, CD-3, CD-4, CD-9, CD14 v CD45. X khun : C1, C3, CD30, CD-62, CD69, CD-99, CD-108, CD-512, CD-610, N24 v N43 Chng C5 l chng vi khun Gram m cha phn loi c n loi cho nn

chng ti khng dng sn sn xut ch phm Micromix 3. u im ca cc chng trn c nhit sinh trng v sinh tng hp xenlulaza

tt t 45 - 55oC, ph hp vi nhit ca cc b x l rc thi ca cc x nghip ch bin rc hiu kh nc ta to = 50 2oC. pH ban u thch hp cho sinh trng v sinh tng hp enzym t 6 - 10. Chng sinh trng d dng trn cc ngun c cht r tin nh xenluloza, tinh bt, r ng v bt u tng. Nghin cu cc iu kin ln men, nhm a ra quy trnh nhn ging sn xut ch phm Micromix 3 ph hp vi iu kin hin nay nc ta.

1. Nhn ging trong bnh tam gic:

Cc chng ging trc khi cy vo bnh tam gic c cy li trn cc ng thch nghing cho pht trin tt sau mi cy vo bnh tam gic v lc trn my lc 220 vng trn pht t 24 - 36 gi 45oC.

2. Nhn ging trong bnh ln men 10 lt (ging cp 2)

Sau khi nhn ging cc chng vi khun v x khun trong cc bnh tam gic mc tt c b sung t 5 - 10% hn hp cc chng vi khun v x khun vo hai bnh ln men c sc kh v nui nhit t 40 - 45oC. Kt qu phn tch s lng ca tng vi khun ln nht t 24 - 36h, cn cc chng x khun t 48 - 60h. V vy,


206

thi gian lm ging cp hai ca hn hp cc chng vi khun trong bnh ln men tt nht 24 - 36h, cn cc chng x khun 48 - 60h. y l thi gian cc chng vi sinh vt ang sinh trng tt b sung vo mi trng nhn ging xp.

Bng 6.5 S sinh trng ca hn hp vi khun v x khun trong bnh ln men 10 lt

Thi gian, h Mt t bo vi khun (OD, = 560 mm) Sinh khi x khun, mg/ml

0 0,147 0,12

12 0,767 0,20

24 1,95 2,31

36 2,23 4,78

48 1,98 6,85

60 1,73 7,43

72 1,52 7,25

3. Nhn ging trn mi trng xp

Mi trng xp phi m bo m 50 - 55%, c p thnh ng cao 0,5m, hng ngy c o trn, nhit 40 - 50oC. Kt qu phn tch s lng cc nhm vi sinh vt trn mi trng xenluloza c trnh by bng 5.6.

Bng 6.6 S pht trin ca cc nhm vi sinh vt trong quy trnh sn xut ph phm Micromix 3 (CFUg-4, nui kim tra 45oC)

Thi gian ln men

1 3 6 9 12 Nhm vi sinh vt

Mi trng

kim tra S lng vi sinh vt (CFU/g)

Vi khun Xenluloza 3,2.105 2.7.109 7,5.1012 8,5.1013 8,9.1012

X khun Xenluloza 3,5.105 2.5.105 8,2.108 7,4.109 8,2.109+

Nm men Xenluloza 1,1.101 2.7.102 2,1.102 3,5.102 2,7.102

Thi gian ln men sn xut ch phm Micromix 3 trn mi trng xp thng ko di t 10 - 12 ngy. Mc d khng b sung nhng nm mc vn pht trin trn b mt ca ng vi s lng khng nhiu.

6.3.3.3 Thi gian bo qun ch phm Micromix 3:


207

Kt qu nghin cu thnh phn v s lng ca nhm vi sinh vt trong ch phm Micromix 3 c bo qun trong ti polime hn kn ni thong mt, ch phm Micromix 3 c th bo qun nhit bnh thng trong thi gian hai thng.

T cc kt qu nghin cu trn c th a ra quy trnh nhn ging sn xut ch phm Micromix 3.

Qua nhiu ln th nghim c th nhn thy ph phm Micromix 3 m bo cht lng tt, khng s dng ch phm lm ging ln men sn xut ch phm tip, nu s dng nh vy th hiu sut x l rc thi s gim.


208

Hnh 6.1 S quy trnh sn xut ch phm Micromix 3

ng dng ca ch phm Micromix 3 trong phn hu rc thi giu xenluloza

Chng vi khun Chng x khun gc

Hot ho

Chng hot ho

Nhn ging lc 40-50oC, 18 - 24h

Mi trng nhn ging II

Ging cp I

Mi trng ln men xp

S dng Bo qun

(ni kh mt)

Hot ho

Chng hot ho

Nhn ging lc 40-50oC, 30 - 36h

Ging cp II

Ging cp II

Micromix 3

Ln men (10 ngy, c o trn)

Hn hp ging

Mi trng thch nghin cu

Nhn ging sc 40 - 45oC, 24h

Bao gi

Ging cp II

Nhn ging sc 40 - 45oC, 36 h

Mi trng nhn ging I

Kim tra vi sinh vt


209

1. Kh nng phn hu rc thi quy m x nghip Th nghim c thc hin ti X nghip Ch bin Ph thi Cu Din H Ni,

dung tch b 150 m3. B th nghim c b sung 30kg ch phm Micromix 3 v b i chng b sung ch phm ca X nghip. Quy trnh th nghim c tin hnh theo quy trnh ca X nghip. Nhit ca b c khng ch khng qu 50oC 2oC bng qut thi kh hon ton t ng.

S bin ng ca cc nhm vi sinh vt trong phn hu rc thi c s dng ch phm Micromix 3

Kt qu nghin cu s bin ng ca cc nhm vi sinh vt cho thy vi khun v x khun a nhit c kh nng phn gii xenluloza trong b th nghim sinh trng nhanh hn v nhiu hn trong b i chng. Trong qu trnh phn gii cc cht hu c bng phng php hiu kh, nhit lng trong ng to ra nhiu hn ng ngha vi tc sinh trng ca vi sinh vt trong b mnh hn.

S ln qut hot ng trung bnh trong mt ngy ca b th nghim cao hn hai ln b i chng. iu chng t rng, trong thi gian gn y vi sinh vt phn gii cc cht hu c trong b th nghim pht trin tt hn, nhit lng to ra nhiu hn nn qut phi hot ng nhiu hn.

Vic b sung ch phm Micromix 3 vo b x l rc thi rt ngn c thi gian x l c thi kh t 47 ngy xung cn 32 ngy.

2. Cht lng mn sau khi : Lng mn b b sung ch phm Micromix 3 nhiu hn b i chng: vi 150

m3 rc , b i chng ch thu c bnh qun 45 m3 mn, trong khi b th nghim thu c 55,5 m3 mn tng t 20 - 25%.

Bng thnh phn mn rc ca b rc thi sinh hot

B Mn, % C, % N, % N phn hu, % P,% K,% Axit

humic, %

i chng 1 30,72 2,52 0,08 0,01 0,52 0,95 0,47

i chng 2 37,64 3,78 0,09 0,12 0,67 1,05 0,52

i chng 3 122,52 150 112,5 120 128,85 110,53 110,64

Kt qu nh gi cht lng mn rc sau khi (bng 5.7) cho thy cc ch tiu

phn tch b th nghim u cao hn b i chng trn 10%, trong lng mn cao hn 22,52%, hm lng nit d tiu - 20%, axit humic tng 10%.


210

3.2 nh hng ca ch phm Micromix 3 v mn rc ln s sinh trng ca cy:

Mt ch phm mun c p dng trong nng - lm nghip, ngoi vic ch phm c hot tnh sinh hc kch thch s sinh trng ca cy, khng gy c cho cy, khng nh hng n kh nng ny mm ca ht v qu trnh pht trin ca cy. Do , ch phm phi c kim tra c tnh v cht lng trc khi bn cho cy.

nh hng ln bo tm (Lamna acquinotialis welwitsch T93): Bo tm lemna l mt loi thc vt pht trin rng ri v rt mm cm vi tc ng ca mi trng. Cc nh khoa hc Thu in v M la chn chng bo tm Lemna acquinotialis lm biotest v a ra quy trnh nh gi cht lng nc thi v cc cht c c tnh bng cch xc nh nng c ch sinh trng 50% (EC 50).

- EC 50 ca ch phm Micromix 3 : 198 g/l - EC 50 ca mn rc th nghim ti Vin Cng ngh Sinh hc : 292 g/l - EC 50 ca mn rc X nghip Ch bin Ph thi Cu Din : 293 g/l Nh vy ch phm Micromix 3 v mn rc c x l bng ch phm ny u

khng gy c cho cy, v i vi bo tm Lemna acquinotialis T93 nhng cht c xem l gy c c EC 50 di 100 g/l.


211

CHNG VII: TC NHN VI SINH VT TRONG QU TRNH X L

NHIM MI TRNG NC 7.1. VI SINH VT GY BNH V CH TIU V SINH V VI SINH VT TRONG NC CP SINH HOT:

7.1.1. Cc vi sinh vt gy bnh: Mt s vi sinh vt c th gy bnh cho ngi, ng vt v thc vt.

Nhng vi sinh vt gy ra bnh l do chng thc hin cc phn ng trao i trong vt ch. a s vi sinh vt gy bnh l loi sng k sinh v ly thc n t vt ch. Cn dng khc ca vi sinh vt gy bnh l chng sn ra cc c t i vi vt ch. C rt nhiu loi bnh truyn nhim lin quan n nc. V vy ton b cc cng trnh k thut v v sinh phi c kh nng tiu dit c nhng vi sinh vt c mt trong nc. cng chnh l trch nhim to ln ca nhng ngi lm cng tc x l nc.

7.1.1.1. Khi nim v dch t hc v cc ng truyn nhim: C nhiu loi bnh khc nhau, l: Bnh n pht, bnh dch din ra trong mt

thi k hoc trong tng a phng hay trong mt vng rng ln, thm ch trong nhiu nc trn th gii. Bnh n pht khng c tnh lan truyn. Nhng bnh dch lan truyn thng qua ban khu l : ngun gy bnh ng truyn bnh ngi, vt b nhim bnh.

Ngun gy bnh c th l ngi, vt m b mc bnh hoc ngi, vt kho nhng c mang vi khun gy bnh. ng truyn bnh c th :

- Qua nc: Do n, ung nc, tm ra, git gi, ra thc n, rau c, bt a... - Qua thc n hay thc phm ni chung. V trong nhiu loi thc phm c th

cha nhiu loi vi khun gy bnh. - Qua tip xc trc tip hay gin tip gia ngi bnh vi ngi khe. Tip xc

trc tip l do bt tay, hn .... Tip xc gin tip l do cng chung qun o, bt a, dng sch v ...

- Qua khng kh : L do ht th khng kh cha hi nc, bi, vi sinh vt gy bnh; k c m, nc bt ca ngi bnh.

- Qua cn trng : rui mui, b nhng .... Nhng ngi lm cng tc v sinh phi to iu kin sng sao cho vi sinh vt

gy bnh khng th xm nhp vo nc, thc n, khng kh ... nhng ni chng c th xm nhp c th phi c bin php ty trng mi trng. Khi vi sinh vt gy bnh xm nhp c vo ngi. ng vt ch th tu thuc vo nhiu yu t m vt ch c th b hoc khng b mc bnh. a s vi sinh vt gy bnh l loi sng k sinh v ph thuc vo vt ch, ph thuc v tr xm nhp vo vt ch. (V d khng th gy bnh c khi vi khun l (Disenterie) xm nhp vo vt thng) tu thuc s lng


212

vi sinh vt ban u xm nhp vo, iu kin mi trng, bin php tim chng phng bnh.

Nhng loi vi khun gy bnh c kh nng to ra c t ngoi hoc c t ni. c t ngoi l c t do vi sinh vt to ra v tit ra mi trng qua qu trnh sng - hot ng ca chng. c t ni l nhng c t sn ra trong t bo vi sinh vt - tc l nm trong thnh phn ca t bo., Chng ch thi ra mi trng sau khi vi sinh vt cht. Thng thng th c t ngoi nguy him hn c t ni.

Khi xm nhp vo vt ch, cc c t ca vi khun s gy tc ng v lm hi cc chc nng ca c th vt ch. a s cc c t ca vi khun c tc dng c hiu: c loi lm thng tn mng no, c loi lm hi cc c quan trong c th nh thn, gan, phi ...

Khng nht thit bnh pht ra mnh lit ngay t u. Nhiu bnh nh lao... din ra rt nhiu nm v thm ch c mt i ngi bnh.

Ni chung khng bnh no pht ra ngay sau khi ngi bnh b nhim bnh m thng phi qua mt thi gian cc loi vi khun kp pht trin. Thi gian k t lc nhim bnh n lc pht bnh m - gi l thi k bnh.

tiu dit bnh, ngi ta phi trit mt trong nhng khu truyn bnh. Nhng ngi lm cng tc cp thot nc lin quan nhiu nht v trc tip n ng bnh qua nc v c trch nhim dit trng gy bnh trn ng truyn bnh ny.

7.1.1.2. Cc bnh truyn nhim qua nc:

Trong s nhng bnh truyn nhim qua nc th nhng bnh ng rut chim nhiu nht. a s cc loi vi khun gy bnh ng rut u ging nhau v hnh thi, sinh l v thuc h Enterobacteriaceae. Chng l loi trc khun kch thc 1 - 3 x 0,5 - 0,6 , gram m, khng to ra bo t v khng c gip mc. Cc loi vi khun ca tng bnh khc nhau v hot tnh men, kh nng vn ng.

a. Vi khun gy bnh ng rut cho ngi, gia sc, gia cm l: Trc khun ng rut (Escherichia), vi khun bnh thng hn v ph thng hn - typhor v paratyphos (Saimonella), vi khun bnh l Disenterie (Shigella), vi khun bnh t (Vibrio cholerae).

Vi khun Escherichia coli


213

Vi khun E.coli

Salmonella


214

Shygella

Vibrio cholerae - Vi khun Escherichia coli: L trc khun ng rut gy bnh Colenterit tr

em v bnh l Disenterie ngi ln. Trc khun ng rut thng l loi vi khun loi i khng vi vi khun thi ra. C kh nng sinh cht khng sinh nh Colicin lm cht cc vi khun gy bnh khc. Khi dng cht khng sinh dit trc khun ng rut th s kch thch vi khun thi ra v nhng vi khun gy bnh khc.

Nhm trc khun ng rut t bit rt nguy him ch chng rt d thch nghi vi c th ngi. Chng bn vng c vi dch v ca ngi. Trong iu kin t nhin nh nc, t, k c thc phm, da, chng c th tn ti hng tun thm ch hng my thng. Tuy nhin khi un si c th dit cht ngay c. Cc dung dch cht khng sinh 3-5% (nh dung dch Chioramin, phnon, formalin) trong vng 10-15 pht c th tiu dit c chng.

- Vi khun Salmonella: L loi gy bnh thng hn typhos v paratyphos. Trong s cc vi khun ny, c loi ch gy bnh i vi ngi (typhos), c loi gy bnh c i vi ngi ln ng vt (paratyphos). Salamonella rt ph bin trong thin nhin, tn ti trong cc ng vt c sng, ch, mo, chim, chut, c v.v...


215

Khi b bnh typhos hoc paratyphos th rut non b thng tn, ng thi ton c th b nhim c do c t ni (tc l sau khi trc khun typhos b phn hu). Ton b h thn kinh trung ng b tc ng - thng tn - ngi bt tnh.

Salmonella khng sinh sn mi trng bn ngoi nhng c th t bo tn nc sng trong 6 thng, nc bng gi sut ma ng, nc ging khi trong 4 thng, nc cp thnh ph di 3 thng.

Trong nc thi v c s cnh tranh vi cc loi vi khun khc nn Salmonella ch sng c khong 40 ngy, Chng c th sng trong thc phm, rau qu ... cho ti khi rau qu b thi ra, sng trong bia c 2-4 ngy.

Salmonella bn vng c i vi nhng khng sinh hoc iu kin kh ro. Dung dch thu ngn 10/00 v dung dch axit cacbonic 5% phi sau na gi mi tiu dit c chng. Tt nhin khi clorua ho nc cp s tiu dit c Salmonella.

- Vi khun Shigella: Xm nhp vo c th qua ming ri pht trin nim mc, i trng. Khi t bo vi khun cht, gii phng c t ni. c t ngm vo thn kinh v phn ng li gy tn thng rut.

Khi bnh pht ra th thng b a chy c mu ln mi. So vi l amibs th s ln i ngoi nhiu hn.

Ngun bnh l ngi mc bnh. Trc khun l Shigella c th truyn do tip xc trc tip, qua thc n nc ung, c bit l do rui nhng.

So vi Salmonella th Shigella khng bn vng bng. Nhng n c th chu ng c nhit thp ti hng thng. Chng c th tn ti nc sng ti 3 thng, nc cp thnh ph 1 thng, nc thi 1 tun.

i vi dung dch st trng axit cacbonic 1%, sau na gi th chng b tiu dit. Kh trng nc cp th bng clorua ho c th tiu dit hon ton trc khun l.

- Vi khun Vibrion gy bnh t Cholera: y l in hnh ca bnh truyn nhim qua nc. Dch t l bnh rt khng khip, lan truyn nhanh v c t l t vong cao.

Vi khun Vibrion l loi phy khun 1,5 - 2, i khi dai ging trc khun hoc c khi ngn ging cu khun. N bt mu tt, gram m, khng gip mc, khng to nha bo, nu soi ti th rt di ng. L loi hiu kh, d dng nui cy trn cc mi trng kim yu; khng bn vng i vi mi trng axit. Khi axit ca d dy yu i th rt d mc bnh ny. Vi khun vibrion xm nhp vo c th bng thc o, pht trin nim mc tiu trng, gii phng ni c t gy ra mt lot triu chng in hnh: lng nc ngng t rt ln (ti 30lt/ngy m), nn ma v i ngoi lng. C th b mt nc nghim trng, cng cc qu trnh gy oxy ho gim v cc sn phm cha kp chy ht (CO2) s ng li cc m ... T l t vong rt cao.

Phy khun t Vibrion rt nhy vi nhit cao. un nng ti 52oC sau 30 pht l cht, ngc li rt thch nghi vi nhit thp. nc sng, nc ging chng bo tn c 3 thng, nc cp sinh hot 1 thng. Nc thi l mi trng tt nht i vi chng nn chng c th tn ti c ti 7 thng. nc bin phy khun t cn c th sng lu hn, c th sinh sn vi tc cao hn nc ngt


216

Phy khun t b tiu dit dung dch axit cacbonic 1% trong 5 pht, dung dch thu ngn 0,1 % th cht ngay trong nc khng c cht hu c hoc vi nng Clo 0,01% th chng cng cht trong vng 15 pht. phng bnh t nn ra hoa qu bng dung dch axit axtic long v khuy khun t khng chu ni mi trng axit. Cc vi khun gy bnh ng rut, trong c vibrion, u b cht khi un si nc.

b. Cc bnh khc ly truyn qua nc: Ngoi cc bnh ng rut cn c cc bnh khc c th ly truyn qua nc nh: - Bnh do Leptospira l bnh in hnh truyn qua nc. Nhim bnh ny l do

dng nc b nhim khun do tm. Nc b nhim khun l do chut a vo. Ngi ta phn bit hai dng bnh do leptospira l : Veilia (st da vng) v st rt nc. Leptospira l loi vi khun hiu kh nhng chng chu ng c mi trng t oxy, rt di ng thch nghi nhit thp, tn ti c 5 thng nc sng, 2 thng nc ging.

+ Bnh st da vng l bnh truyn nhim. Triu chng ban u l st cao t ngt, au cc c v au u. Vi khun xm nhp v lm hu hoi gan, thn hoc chy mu rut.

+ Bnh st rt nc khc ch vi khun thng xm nhp qua cc ch xy da do tm v ngi bnh khng vng da - mt .

phng bnh do Leptospira ngi ta phi c bin php bo v ngun nc, dit chut, tim chng vacxin. i vi h thng cp nc th, phi tin hnh kh trng bng clo hoc cc cht dit trng khc.

- Bnh l amit (amebs) - trong thi gian m cng din ra nh bnh l thng. Amip l thng gp trong nc, t v trong c th ngi. Amip gy bnh l c tn l Eltamoeba histolytica.

- Bnh bi lit - Polyomealit - thng xy ra tr em. Bnh do virut xm nhp vo cc c quan h tiu ho. Loi virut ny rt bn vng. N chu ng c iu kin kh ro, nhit thp, un si ti 600C l cht trong vng 15 n 20 pht. Cc cht st trng nng thng dng u tiu dit c virut bi lit.

- Bnh Tular : Bnh ny biu hin b ngoi c im ging bnh dch hch. Tuy nhin ch l b ngoi m thi. Bnh ny truyn bng nhiu ng nhng phn ln truyn qua nc l chnh. c trng ca bnh ny l hu hoi tuyn bch huyt. Tuyn ny sng ln. Vi khun gy bnh l loi hiu kh nhng khng to bo t, lc non dng trc khun, khi gi dng cu khun bt ng. Nhit thch hp nht i vi chng l khong 37oC. Vi nhit cao 56 -58oC trong vng 10 pht l chng b cht. Chng chu ng c nhit thp. nc sng chng bo tn c 1 thng, nc ging 2 thng, nc cp th 3 thng. dung dch thy ngn 1% ch trong 3 giy l chng cht ht. Kh trng bng Clo cng tiu dit chng.

Ngun truyn bnh l chut cng, chut ng v chut nh. phng v chng bnh Tular ngi ta dit chut v dng vacin.

- Bnh vim kt mc: Trong cc th c nhiu b tm th nhng ngi tm b hay b bnh vim kt mc.


217

c. Cc bnh truyn nhim do virus: Ngoi nhng bnh truyn nhim do vi khun cn c nhiu bnh khc truyn qua

nc do virut. in hnh nht l bnh poliomielit. - Bnh bi lit tr em hay cn gi l bnh vim tu xm. Bnh do loi virut. l loi virut rt bn vng. N chu ng c c nhit sy nng v nhit thp. Tuy nhin nu tng nhit ti 600C th hot tnh ca chng gim v trong vng 15 + 20 pht l chng b tiu dit. Loi virut ny c rt nhiu trong nc thi. Nhng khi x l nc thi trong b arten hoc x l cn trong b mtan th chng u b tiu dit.

Cc cng trnh x l nc cp kh c hu ht cc loi virut ny bng cch kh trng nc cp bng Clo vi nng d 0,2 - 0,5 mg/l.

Sau y l hnh nh v mt s vi sinh vt gy bnh:

Candida albicans (dng lng hnh) Gy bnh nhim nm men ngi

Bacillus cerens Gy bnh ng c thc phm ngi


218

Staphylococcus aurens gy bnh ng c thc phm

Pseudomonas acruginosa gy bnh c hi trn ngi

Chostridium perfringens gy bnh ng c thc phm


219

7.1.2. Cc ch tiu v sinh v vi sinh vt 7.1.2.1. Cc khi nim chung v nhng vi sinh vt ch th v sinh Mc ch ca vic kim tra v sinh trong nc l xc nh mc an ton ca

nc i vi sc kho con ngi. V mt vi trng hc, ta phi tm nhng loi vi sinh vt gy bnh truyn nhim cho ngi. Tuy nhin c rt nhiu loi vi sinh vt gy bnh c th tn ti trong nc do phn lp chng trong nc l mt vic lm rt kh, khng th thc hin c. Mt khc c th c c kt qu phn tch t nht cng phi mt 2 -3 tun l - (tc l khi dn chng ung nc nhim trng ri). V vy t lu (cui th k 19) ngi ta c gng tm ra mt loi vi khun in hnh no d d gy bnh hay khng gy bnh nhng c trong phn ngi v i din cho tt c cc loi vi sinh vt gy bnh trong nc. Ni cch khc, s c mt ca nhng vi sinh vt i din trong nc cng ni ln s c mt ca nhng vi sinh vt gy bnh khc trong nc, tc l nc b nhim bn bi phn ngi. Cui cng ngi ta cng thnh cng. Trong phn ngi thng xuyn c mt ba loi vi sinh vt :

- Trc khun ng rut Escherichia coli - Cu khun: Streptococcus - Vi khun ym kh to nha bo Clostridium theo Huston v Klein trong 1ml

nc thi sinh hot cha t 100.000 - 800.000 trc khun ng rut; t 1000 - 60.000 cu khun v t 100 n 2000 vi khun ym kh to nha bo. Nh vy trong nc thi sinh hot lng trc khun ng rut chim nhiu nht. Tuy nhin y khng phi l vn chng nhiu v s lng, l gi tr ch yu ca vi sinh vt ch th v s nhim phn l tc cht ca chng phi xp x vi tc cht ca a s vi sinh vt khc. Ch c loi vi sinh vt no thng xuyn c trong phn ngi v tun theo iu kin trn mi c th dng lm ch tiu v s nhim bn do phn c.

Xt 3 loi vi khun c trong phn ta thy: Vi khun nhm Clostridium bo tn trong nc lu hn nhng vi sinh vt gy bnh. Cu khun li chng cht hn. Cn trc khun ng rut c thi gian bo tn trong nc gn ging nhng vi sinh vt gy bnh khc. Do trc khun ng rut l ch tiu v sinh ch yu v s nhim bn nc.

Ngoi ra ngi ta cn kin ngh hai loi na l vi sinh vt a nng v thc khun th (bacteriophage) lm hai ch tiu ph. Tuy nhin tt c cc ch tiu v sinh trn u gi l ch tiu gin tip v chng cho bit mt cch gin tip v s nhim nc bi vi sinh vt gy bnh. Nu khi c bnh dch xy ra, cc nh vi sinh vt phi xc nh chnh xc loi vi khun no gy ra bnh dch. Khi gi l ch tiu v sinh trc tip v s nhim bn nc.

7.1.2.2. ngha ca ch tiu v sinh v trc khun ng rut Trc khun ng rut l ngun gc u tin gy ra cc bnh thng hn, ph

thng hn v l. Trong qu trnh tin ho ca mnh n c kh nng k sinh vo vt th sng ng thi mt dn kh nng s dng trc tip cc cht ho hc khc lm thc n. T hnh thnh cc loi trc khun gy ra cc bnh trn y. Nhm trc khun ng rut Escherichia Coli c rt nhiu trong rut gi ca ngi: t 100 triu n 1 t


220

con trong 1 gam phn ngi. Con ngi sau khi sinh ra c 20 gi trong rut gi a tr c cha nhiu vi khun, nhng vn cha c trc khun ng rut. Qua hng tun, hng thng khi a tr bt u c nui bng thc n tp th E. Coli mi theo vo rut v c tr rut gi ca tr, t chng tn ti trong ngi mi mi cho n lc ngi cht. Trong qu trnh sng - hot ng sinh l ca ngi. E.Coli theo phn thi ra mi trng. E.Coli c trong phn tt c cc loi sc vt, chim mung hoang di (nhng loi khng tip xc vi ngi). Nh vy E.Coli l ch tiu v sinh r rng, hin nhin v s nhim bn mi trng do hot ng ca con ngi.

nh ga mc nhim bn ca nc v vi sinh vt, ngi ta dng hai ch tiu l cli titre v Coli ch s.

Chun coli (coli titre) l th tch nh nht ca nc (tnh bng ml) trong 1 t bo cha 1 Coli. Chng hn khi ni Cli titre l 333, ngha l c 333ml nc c cha 1 trc khun ng rut.

Ch s coli: l s Coli cha trong mt lt nc. Th d: Coli ch s l 3, tc l c 3 Coli trong mt lt nc.

Mi quan h gia Coli ch s v Coli titre l s nghch o ca nhau : 1000

Coli ch s Coli titre

7.1.2.3. ngha ca ch tiu v sinh v vi sinh vt a nng tng sn lng thu hoch nng nghip, ngi ta thng dng phn ngi, sc

vt, nc thi bn rung. Nhng v nhng cht bn trn u cha rt nhiu trc khun ng rut v u c th dn n nhim bn ngun nc, nht l ngun nc ngm. Khi c dch xy ra, ngi ta phi tm nguyn nhn v cn bit r bnh dch xy ra do bn rung bng phn ngi hay sc vt. Mun vy, ngoi ch tiu v E.Coli ngi ta phi phn tch xc nh lng vi khun a nng. Phn ngi v nc thi cha rt t vi khun a nng, nhng phn sc vt - phn chung th li cha rt nhiu. Nh th ngi ta s xc nh c nguyn nhn ca s nhim bn t v nc thi l do bn loi phn no.

7.1.2.4. ngha ch tiu v sinh v Thc khun th: (phage) Thc khun th (phage) sng k sinh vo vi khun. Khi vng mt vi khun tng

ng ca thc khun th th thc khun th vn tn ti c kh lu trong nc. Chng ch cht khi khng nhn c thc n m thi. V vy nu pht hin thy thc khun th (ng vi loi vi sinh vt gy bnh) trong nc th chc chn cng c vi sinh vt gy bnh hay ang tn ti.

7.1.2.5. ngha ch tiu v sinh an ton v giun

C hai loi giun sn l : giun sn a cht v giun sn sinh hc. Giun sn a cht l loi giun sn m trong qu trnh pht trin khng cn nh vt ch trung gian. Giun sn sinh hc l loi phi sng nh vo hai hoc ba vt ch trung gian.

Giun a cht gm: Giun a, giun kim, giun tc... Giun sinh hc gm giun bi, sn ch, sn x mt, giun xon ...


221

Mi trng bn ngoi (t, nc) b nhim bn bi giun sn l do nhim phn cha giun sn.

Con ngi b nhim giun sn l do n phi trng giun hoc b trong nc, tri cy, thc n, ... ti sng.

Trong nc thi sinh hot v do nc sng h b nhim bn bi nc thi nn cng cha nhiu loi giun nh giun a , giun kim, .... Trong rut ngi, ng vt cha rt nhiu trng giun, trng giun ny theo phn ra mi trng bn ngoi - ln vo t, nc, tri cy, rau ti... T chng li xm nhp vo ngi, ng vt v gy ra khng t nhng bnh him ngho.

7.1.2.6. nh gi nc dng n ung: p ng yu cu v cht lng cht lng thc n ung l mt vn kh v

phc tp. Nc dng n phi p ng c nhng yu cu sau : - Khng nguy hi i vi c th ngi, phi hp khu v. - Tin cho vic nu thc n. - Tin cho vic ra, git r qun o ... y ch yu ch xt yu cu u tin : - Nc dng n ung phi c nh

gi theo cc mt: vi trng hc, sinh hc, l ho hc, gic quan v sinh, a hnh ... 1. nh gi v vi trng hc Nc dng n ung khng c cha bt k loi vi khun gy bnh no.

Nhng ng thi c rt nhiu loi vi khun gy bnh, nn khng th xc nh s c mt ca tng loi trong mt mu nc, tc l khng th phn tch ch tiu trc tip. V vy ch tiu v sinh v vi trng hc c nh gi mt cch gin tip, bng trc khun ng rut, v tng s vi khun (MNP - Most Probable Number).

2. nh gi v sinh hc Trong nc n ung khng c cha trng giun sn, ng thc vt ph du.

Nhng loi ng thc vt ph du tuy khng c hi nhng nu c trong nc cng lm ngi dng nc nhn thy gh s, v chc chn cng mang theo vi khun.

Trong cc ngun nc mt, nht l h m thng c hin tng ph dng n hoa (Eutrofication). Do trong nc s cha cc sn phm trao i hoc cc sn phm phn hu t bo to ru v lm nc c mi v khc thng: tanh, hi,thi ...

3. nh gi v vt l Nc dng n ung phi trong sch, khng mu, mi, v, pH v nhit phi

nm trong gii hn quy nh theo quy phm. 4. nh gi v ho hc

Trong thnh phn nc t nhin cha nhiu tp cht ho hc khc nhau k c cc cht phng x. - Cc cht khong cha rt nhiu trong nc thin nhin, trong c nhiu hp cht cn cho c th con ngi. Tuy nhin, nhng cht (amino, cation) c b sung ch yu t thc n ch khng phi t nc (tr iod v fluor). Nh vy s c mt ca nhng ion s lm cho nc c cm gic ph hp l chnh.


222

- Iod cn thit cho s hot ng bnh thng ca tuyn gip (mi ngy c th ngi cn 300g iod). Nu thiu th tuyn gip hng b km pht trin, b ngoi gi l bnh bu c, kh nng t duy km - con ngi sinh n n mt thng minh. Ngun chnh b sung iod cho c th ngi l nc, nht l nc bin. T nc bin, iod theo hi nc bay vo kh quyn ri theo ma vo t lin - sng - h - t. Cng nhng vng cao v xa bin lng iod trong kh quyn cng t. Do nc nhng vng cao nguyn cha t iod v bnh bu c pht sinh nhiu. chng bnh bu c ngi ta phi ioduor ho nc, b sung mui iod vo thc n.

- Fluor cng l mt trong nhng nguyn t ph bin trong thin nhin. Nc mt cha t Fluor hn so vi nc ngm. Nu nng Fluor trong thc n ung qu thp (di 5,5 - 0,7 mg/l) s lm mc xng rng (b rng rng). Nu nng Fluor qu cao (trn 1,5mg/l) s lm ngi ta nhim c Fluor. Do vy nng Fluor ti thch trong nc ung l 0,7 - 1mg/l. Nu ngun nc khng Fluor ngi ta phi cho thm vo.

- Cht phng x cng c trong nc thin nhin v trong khng kh xung quanh ta vi mt lng rt t. Tng lng cc cht phng x trong c th ngi khng ng k. S c mt ca cc cht phng x vi mt lng ng k trong c th ngi s dn n hu qu l c th thng b tc ng ca cc atia , , .

S pht trin ca cng nghip hin i s lm cho nc thi cha nhiu cht phng x v do c nc thin nhin, ngay c ng thc vt, thc n ca ngi, cng cha nhiu cht phng x.

- Nitrat: l mui ca axit nitric, cha nhiu trong nc mt v nc ngm. C nitrat trong nc chng t c cc loi mui ho tan v chng t c cc mui ho tan v chng t c qu trnh khong ho cc cht bn hu c din ra.

Nitrat qu nhiu trong nc ung (trn 10 mg/l) gy nguy him i vi tr s sinh 2-3 thng, v n gy ra bnh thiu mu methemoglobine.

- Cht hu c: Trong nc thin nhin, theo ngun gc, nhng tp cht hu c c th chia ra:

+ Cc cht hu c sng.

+ Cc cht hu c cht (cn b hu c)

+ Sn phm trao i ca cc vi sinh vt sng ln vo nc.

+ Cc cht hu c cng vi nc thi sinh hot, cng nghip x vo ngun nc.

Theo mc phn hu, ngi ta chia ra: cc cht d phn hu, kh phn hu v nhng cht c.

Ch tiu COD (oxy ho) nh lng tng cng tt c cc cht hu c trong nc nhng khng xc nh c lng cc cht d hoc kh phn hu. Khi tt nht l xc nh ch tiu NOS (BOD) - tc l i lng phn nh lng cc cht hu c d phn hu. Nc ngun dng cp nc sinh hot c NOS = 2 - 3 mg/l, i khi hn mt cht nhng khng c qu 4mg/l.


223

5. nh gi theo gic quan

i vi nc dng n ung, khi nng cc tp cht rt thp, i khi cc phng php phn tch ho hc khng chnh xc th ngi ta dng gic quan th. C th dng 3 trong 5 gic quan ca ngi (v, khu, th gic) nh gi cht lng nc ung. Tt nhin khi nc c, c mu, mi, v khc thng th con ngi s cm thy c. l phn x t v t nhin ca ngi.

- Mu: Nu nc trong sch th nc khng mu. Nu c mu, chng t nc thin nhin cha tp cht nh hutnic, tanin, mui st ...

- Mi: Nc dng n ung, khng c c mi. Nu c mi chng t nc b nhim bn v nguyn nhn c th l : do to thnh H2S, sn phm ca s phn hu cc cht hu c c cha S hoc do c FeS2, cht ny tc dng vi axit cacbonic ri to thnh H2S. C th do cc sn phm thi ra hay do cc vi sinh vt ph du pht trin trong nc.

- V: Nc dng ung c v "ngon" c bit. Tt nhin y c th sai lch do cm gic ch quan ca tng ngi, ca dn tng a phng. Thng nu nc c cha CO2 th lm cho nc c v ti mt. Nu nc c cha cc loi mui khong ngi ta cng d thy: nh mui NaCl thy mn, cc loi mui khc c th cht, axit hu c thy chua...

6. nh gi theo trng thi v sinh a hnh

Tt c cc phng php nh gi trong phng th nghim trn ch c trng cho mt dung tch nh ca mu nc phn tch (1-2lt). Trong khi nh ta bit :cc loi vi khun, cc cht hu c phn b khng u ton khi ngun nc. Do cn phi nh gi v trng thi v sinh a hnh. Ni dung cng vic bao gm:

a) Nghin cu bn a l, a cht khu vc xung quanh ngun nc: y ta s xc nh c nhng h, nhnh sng chy ti b cp, nhng vng dn c, cng nghip c kh nng gy nhim bn ngun nc... V mt ct a cht, tnh cht ca hai b, y sng, h.

b) Quan st ngun cp nc, cc im gy nhim bn ngun nc : nc thi sinh hot, cng nghip, nh tm, git cng cng, lc s tnh hnh dch bnh vng dn c... Nu ngun cp nc l ngun nc ngm th song song vi mt ct a cht phi xt tr lng nc, v tr v bin php khai thc nc, tnh trng mng li thot nc vng dn c ln cn.

7.2. S NHIM BN NGUN NC, QU TRNH T LM SCH CA NC NGUN (SNG, H)

Nhn chung nhng qu trnh sinh ha din ra khi x l nc thin nhin khng phc tp nh khi x l nc thi, v cc cht hu c trong nc thin nhin, nc cp


224

t hn c v lng cng nh loi cc cht. Chng ta hy xt cc loi ngun nc, s nhim bn v qu trnh t lm sch ca nc ngun, t bit l ngun nc mt to c s cho qu trnh lm sch nc trong cng ngh x l nc.

7.2.1. Cc loi ngun nc: Tt c cc loi nc trong thin nhin u qua dng nc ma. Nc bay hi t

i dng, ngng t li thnh nhng m my ri li ri xung lc a thnh ma, tuyt. Sau nc tp trung vo sng h r li chy ra bin, i dng. Chu trnh thy vn gm 3 ngun nc: Nc ma, nc mt, nc ngm.

- Nc ma: V mt v sinh, vi trng hc v ha hc, th nc ma sch nht,

ch c nhc im l nng mui trong qu t. Nc ngm: V mt v sinh th nc ngm km nc ma, nhng sch hn nc

mt. Nhiu khi khng phi x l m vn s dng c. Thc cht nc ngm l do nc mt thm xung t. Thnh phn ha l ca nc ngm ty thuc cu to a cht v thnh phn nc mt.

i vi nc ngm, s nhim bn v vi khun rt a dng. Thng thng nc ngm mch nng b nhim bn nhiu hn so vi nc ngm mch su. Cng thm su xung lng t, vi khun cng t i bi v nhng lp t trn cng c kh nng gi li hu ht vi khun. Nhiu s liu cho thy di cc h phn, vi khun khng th thm nhp xung chiu su 30-40cm cch mt t. Tuy nhin c khi su 1.5m v hn na cng pht hin thy vi khun v lm nc ngm b nhim khun.

Hnh 7.2 S chu trnh thu vn


225

Cc cht ha hc thm xung lng t su hn. Nhng trong qu trnh thm thu cng vi nc xung t, cc cht c th b thay i thnh phn. Chng hn cch mt t 0.5m nhiu cht hu c b phn hy hoc oxy ha. Ngi ta nghin cu, phn tch v cho thy su 30.5cm NOS khng vt qu 5ml/l, thm ch khi NOS ban u trn mt t l 100mg/l, su khng cn thy phosphat na.

Vi khun v ha cht khng ch thm thu theo chiu su m cn khuych tn theo chiu ngang. Th nghim cho thy cng vi nc ngm, cc ha cht khuych tn xa hn vi khun (xem bng sau).

Khong cch gii hn khuych tn (m)

Tc gi Vi khun Ha cht

Stibes, Croburst (Buthor 1954) Stibes, Croburst (Buthor 1954) Caldwell (Buthor 1954) Muscat (1941) Kipichnicoy (1946)

20 70 15

Hng chc 6

34 135 90 150 40

Khong cch khuych tn ty thuc lng bn ban u, tnh cht t, kch thc

ht. Tuy nhin, c th coi rng vi sinh khng th thm vo ging nc cch xa ngun bn 20m i vi t st, 200m i vi t ct (Jucp & Ampolski 1951).

- Nc mt: Khi nc ma ri xung t, chy vo cc sng h gi l nc mt. Nc mt bn nht c v vi sinh vt, cht hu c, v c. Nc mt rt giu cc cht dinh dng mi trng tt cho nhiu vi sinh vt pht trin, k c nm v ng vt h ng.

7.2.2. S nhim bn ngun nc mt: S nhim bn ngun nc c th do t nhin hoc nhn to. Cc cht bn c th

dng cht l lng, keo, tan, cht c, vi sinh vt, sinh vt S nhim bn t nhin l do ma ri xung mt t, ko theo cc cht bn xung sng h hoc do cc sn phm sng, hot ng pht trin ca sinh vt, vi sinh vt - k c xc cht ca chng. S nhim bn nhn to ch yu do nc thi vng dn c th, cng nghip cng nh tu thuyn x ra.

- Nhim bn t nhin: Nc ma hay tuyt l ngun b cp cho ngun nc mt, nc ngm. Thnh

phn nc ma bin i theo thi gian, khng gian v ty thuc lng cc tp cht bn trong khng kh, trn mt t. Nu trong nhng khu vc nghin cu ht nhn th nc ma cha c nhng cht phng x. Ngay c lng ma cng nh hng ti thnh phn nc sng h. nu tnh rng vi thi gian 20, th lng nc ma H Ni hay cc thnh ph Vit Nam s l bao nhiu v tp trung vo sng h cha bao nhiu cht bn t cc mt ph, mt t cc vng?


226

Nc ma cng rt bn v nh hng nhiu ti ch dng chy ca sng h v cht lng nc trong .

- Nhim bn nhn to: - Nc thi th: l nc thi sinh hot v cng nghip trong phm vi

th. Trong nc thi th cha rt nhiu vi sinh vt, giun sn, c vi sinh vt gy

bnh, nht l vi sinh vt gy bnh ng rut. Chng chim mt khi lng ng k trong cc cht hu c trong nc thi.

V thnh phn c l, cht bn trong nc thi bao gm cc cht l lng khng tan (huyn ph), keo v tan. Theo Heukelekian v Balmat, trong nc thi sinh hot cc cht dng huyn ph cha 80% l hu c, keo, cc cht tan ch yu l cc cht khong. Cc cht hu c trong nc thi sinh hot ch yu l cc cht bo, m (cha nit), ng (cha carbon) nh xenlulo, hemixenlulo, pectin, tinh bt Ngoi ra trong nc thi cn cha cation Na+, K+

- Nc thi sn xut cng nghip: Nhiu lnh vc cng nghip tiu th v thi ra mt lng nc khng l nh cng nghip luyn kim en, ha hc, ch bin lc ha du, dt nhum, thc phm Thnh phn tnh cht nc thi cng nghip rt a dng. Ngoi cc cht bn thng thng, trong nc thi cng nghip cn cha cc cht c hi. Khi ln vi nc ngun, chng s tiu dit cc loi thy sinh vt. Khi nn cng nghip cng pht trin, cc cht bn mi xut hin cng nhiu, mc c ca chng i vi sinh vt li cha r. V vy phi xc nh c ca chng cng nh nng gii hn cho php i vi cc loi sinh vt, phi xc nh mc cn thit lm sch, cc phng php x l nc thi.

Trong cc x nghip cng nghip cn c c cc loi nc thi quy c sch. l cc loi nc lm ngui thit b, sn phm, nht l cc nh my nhit in. Tuy nc ny khng bn, nhng c th ngu nhin do s c thit b nn cng c th lm nhim bn ngun nc. Cc loi nc ny c th lm nhit nc ngun tng ln, lm ngo oxy trong hoc lm sinh vt b tiu dit.

- Nc ti tiu, thy li: Trong nng nghip s dng nhiu nc ti rung. H thng nc tiu ca thy li l sn phm quan trng trong cch mng xanh. Nc ti rung, phn ln thm xung t v bay hi, mt phn quay li h. Phn nc ny mang theo cht l lng xi mn t t, nhiu loi cht c, thuc tr su V khi lng nc ny qu nhiu, khng th thc hin x l lm sch c. Kt qu mt mt gy nhim ngun nc, mt khc lm gim ph ca t. Mt iu nguy him i vi cc vng kh, bay hi mnh: nhng knh mng ti rt nng cn, nn lng nc mt i do bay hi rt ln. Kt qu lm tng hm lng mui trong nc ti v t trng, lm thay i thnh phn nc ngm.

- S nhim bn do vn ti ng thy: Vn ti thy l dng vn ti kinh t nht. Tuy chm nhng ngy nay hnh thc ny rt ph bin. C th ni cc nc, t 50-90% hng ha c vn ti bng ng thy. Trong cng nghip lc ha du, bt k loi du no cng u cha nc. Khi vn chuyn, nc tch li di y tu. Sau khi bm du i, trnh nhim sng bin, ngi ta cm x nc ny gn b bin nu


227

hm lng du vt qu 50mg/l. Cho d x bng cch no cng lm bin b nhim v tiu dit sinh vt bin - nht l thc vt - ngun cung cp oxy cho kh quyn t lin.

Ngoi cc sn phm du, cc tu thuyn cn lm nhim bn sng bin do x nc thi sinh hot. V vy phi c thit b ring trn tu thuyn x l hoc cha ri x ra nhng vng quy nh.

7.2.3. Qu trnh t lm sch ca ngun nc mt: Sng h l nhng cng trnh thin nhin hoc nhn to, l nhng ngun cung cp

nc mt, ng thi l ni tip nhn nc ma, nc thi sinh hot, cng nghip Tt c cc dng nc chy v sng h u mang theo cc cht bn hu c, v c. nhng iu kin bnh thng thch hp th nhng cht kch thch s pht trin ca sinh vt. nhng vng sng, sui vng ni cao th s sng ca sinh vt n iu, ngho nn hn, v t cht dinh dng hn. Nhng nhng con sng chy qua nhng vng ng bng ph nhiu mu m, dn c ng c, tr ph th hot ng sng ca sinh vt rt phong ph v y cht hu c, cht dinh dng. Nu cc cht bn (theo lng tng cht v s loi cht) va ph hp vi kh nng ng ha ca sinh vt th cc qu trnh sinh ha s din ra trong iu kin hiu kh v c li cho con ngi. Nu cc cht bn qu nhiu, vt qu kh nng ng ha ca sinh vt th cc dng sinh vt thng ng s phi b i, ch cn li vi khun pht trin, to iu kin ym kh, gy tn tht cho con ngi. Khi , ngun nc sng h b nhim bn. Ngy nay, do s pht trin th, cng nghip v nn kinh t x hi ni chung, cc dng sng s b nhim bn qu mc, v l mi lo ngi ln cho con ngi.

7.2.3.1. Qu trnh t lm sch: Qu trnh t lm sch ca ngun nc c th chia lm 2 giai on: - Qu trnh xo trn, pha long gia cc dng cht bn vi khi lng nc

ngun. l qu trnh vt l thun ty. - Qu trnh t lm sch vi ngha ring ca n. l qu trnh khong ha cc

cht bn hu c hay rng hn, l qu trnh chuyn ha, phn hy cc cht bn hu c nh cc thy sinh vt, vi sinh vt. mc nht nh, d t d nhiu, tt c nhng c th sng u tham gia vo qu trnh, ng thi chng sinh trng, sinh sn (k c cht) v pht trin. Sinh khi ca chng tng ln.

Trong cc dng sng chy, cc dng cht bn s pha long vi nc sng trn mt khong nht nh. Trong sut khong chiu di , c th phn bit cc vng sau y:

Vng x cht bn;

Vng xo trn hon ton;

Vng bn nht, hm lng oxy ha tan t nht;

Vng phc hi, kt thc qu trnh t lm sch.


228

Cng qu trnh t lm sch ty thuc nhiu yu t: dung lng nc sng,

tc dng chy, iu kin lm thong ha tan oxy theo b mt, chiu su dng chy, nhit , thnh phn ha l ca nc, tnh cht cc cht bn

Trc ht, xt mt s khi nim c bn: a- Tng sn phm s cp trong nc ngun: Theo phng thc dinh dng, tt c cc c th sng trn tri t c chia

thnh 2 loi: sinh vt sn xut v sinh vt tiu th. Sinh vt sn xut l cc loi t dng, to cht hu c bng cch c nh CO2. Sinh vt tiu th l cc sinh vt d dng, ch s dng cht hu c c sn. Sinh vt sn xut bao gm tt c cc thc vt, vi khun t dng (tr nm). Sinh vt tiu th gm tt c nhng loi sinh vt cn li.

Cht hu c to ra trong qu trnh quang ha hp c gi l sn phm s cp. Khi lng ch yu ca sn phm s cp c tng hp nh thc vt. vai tr ca vi khun trong qu trnh ny khng ln lm.

Vic tng hp sn phm s cp l c s s sng trn tri t. Vic ti to cc cht hu c lin quan mt thit vi quang ha, tc l ty thuc iu kin chiu sng. Tuy nhin, lng sn phm s cp khng ch ph thuc cng quang ha m cn ty thuc lng thc vt. D quang hp c mnh nhng lng thc vt trong sng h t th lng sn phm s cp cng t. Ngc li d quang hp c hi yu nhng trong sng h nhiu thc vt ph du v thc vt thng ng th lng sn phm s cp s rt ln. su ngun nc cng tng th chiu sng cng gim v lng sn phm

ng - hot ng Hnh 7.3 nh hng ca cht bn i vi s sng - hot ng

ca sinh vt trong nc sng.


229

s cp s ty thuc nhiu vo s phn b thc vt theo chiu dy lp nc. Thc vt nm lp su, t c chiu sng th sn lng s cp s gim.

Giai on quang hp ngoi nh sng thng ngn hn giai on quang hp trong bng ti, nn to c th sng, tn ti ngoi vng chiu sng tt. Khi ni ln mt nc, chng nhn mt lng bc x mt tri cn thit, khi chm xung su chng s thc hin quang hp ti. Khi kh hu n ha, to phn b trong sng, h khng u, lp trn nhiu to hn lp di. Nh vy phn to b i nh sng bao gi cng t hn so vi khi chng phn b u theo chiu dy lp nc.

Thnh phn ca nc, c th l lng nit, phospho cng nh hng ti lng sn phm s cp. Nhu cu cc nguyn t dinh dng i vi cc loi thc vt khng ging nhau.

- Lng sn phm s cp c biu th bng khi lng (hoc n v nng lng tng ng), c tng hp trong mt n v thi gian. Sn phm c th tnh theo n v dung tch, din tch hoc ton b ngun nc.

Khi quang hp, cc qu trnh ti to sinh khi mi ca thc vt ph du, vic to oxy v nng lng lin quan vi nhau.

Cn ch rng khng phi lc no s tng sinh khi ca to cng ng nht vi lng sn phm s cp.

b- Chuyn ha v phn hy cht hu c: - Sinh khi ca cc sinh vt t dng: To, thc vt nc bc cao, vi khun l

ngun thc n cho cc loi d dng vi khun, nm, ng vt ph du, Necton. Trong s ny c nhm sinh vt c bit gi l sinh vt hoi sinh, khong ha cht hu c cht, chng cung cp cc nguyn t khong cho cho loi t dng.

- Vi khun v nm phn hy cc loi to cht nh h men ngoi bo. Mt phn cht hu c s b khong ha, phn cn li chuyn thnh cc cht n gin hn m chng c th s dng c. Trong t bo cc vi sinh vt , cc cht n gin ny c chuyn ha v nm trong thnh phn ca t bo dng protein v cc cht dinh dng d tr. Nh vy, nhng vi sinh vt hoi sinh tham gia vo vic phn hy cht hu c ca loi t dng v tng hp cht hu c cho t bo ca mnh. Chng l loi d sinh bc 1. Nhng loi d sinh bc 1 cn bao gm c loi ng vt s dng thc vt, k c c hoa. Nhng cht hu c to nn loi ng vt n thc vt (phytophage) l loi d sinh bc 2. C nh vy, to nn cht hu c- sn phm bc 3

c trng cho trnh t chuyn ha cc cht hu c, ngi ta dng khi nim mc dinh dng. Cc loi s dng phytophage - bc 3 Vic chuyn ha cht hu c (v c nng lng trong ) t mc dinh dng ny sang mc khc, s loi v sinh khi ca chng thng gim dn v to ra nhiu thp sinh khi. Nhng loi nh nhng tc sinh sn nhanh vi cng mt sinh khi thng to ra nhiu cht hu c hn cc loi to ln. Tuy nhin cng c khi, sinh khi ca loi thuc mc dinh dng sau ln hn sinh khi ca loi thuc mc dinh dng trc. Sinh khi l tng khi lng ca tt c cc sinh vt thuc mt mc dinh dng no , cn sn phm l sinh khi to ra mt mc dinh dng no trong mt khong thi gian nht nh (trong k c khi lng tiu th, cht hoc tch khi h thng).


230

Khc vi sinh khi, nng lng ca mt cht hu c no khi chuyn t mc dinh dng ny sang mc dinh dng khc th lun lun gim.

Trong bt k mc dinh dng no, thc n do nhng vi sinh vt s dng u khng hp th c ht v bao gi cng cn li mt t. lng hp th c, mt phn tiu hao cho vic tng sinh khi, mt phn b oxy ha sinh nng lng. Nng lng ny li c th s dng cho mc dinh dng tip theo. Phn nng lng tiu th trong cc qu trnh sng, hot ng ca sinh vt, c tn vo khng gian v b loi khi qu trnh chuyn ha cht hu c. Tuy nhin khi tn nng lng, cng din ra qu trnh khong ha cht hu c. ng thi vi vic gii phng nng lng cng gii phng CO2 v cc nguyn t dinh dng vo nc. CO2 v cc nguyn t dinh dng li to ra sn phm s cp - tc l li tch ly nng lng.

Tng nng lng, bao gm tch ly khi tng sinh khi (S), tiu hao trong cc qu trnh trao i cht (T) v cn li phn thc n cha hp th c (C) bao gi cng bng nng lng cha trong thc n ban u (A):

A = S + T + C (n v nng lng hoc lng oxy) Hiu sut s dng thc n c c trng bng cc h s khng th nguyn:

ASK =1 H s s dng thc n tiu th cho sinh trng

TSS

CASK

+=

=2 H s s dng phn thc n hp th tiu th cho sinh

trng K1 v K2 cng cao th hiu qu s dng thc n cho vic tng sinh khi cng cao. S mc nng lng ca loi pelagian (sinh vt ph du) thng l 3-4, ca sinh

vt y l 2-3. VD: Mc dinh dng 1: Vi khun Mc dinh dng 2: Trch trng n vi khun Mc dinh dng 3: ng vt ph du n trch trng Mc dinh dng 4: C b n ng vt ph du Mc dinh dng 5: C ln

C th ni vi khun l nhn t chnh ca qu trnh sinh ha bnh thng trong

ngun nc thin nhin. Chng bin cc cht hu c ha tan thnh t bo ca mnh v

Hnh 7.4 Chu trnh sinh ho t nhin trong sng h


231

cc cht v c. Nhng cht v c li c to s dng xy dng t bo. Nhng vi khun v to li l thc n cho cc sinh vt h ng s dng. ng vt h ng, to, vi khun li l thc n cho c b ri cc loi c li l thc n cho con ngi. Chu trnh c th tip din. Cn ch rng sinh khi ca c chim phn rt nh trong sn phm s cp. Nu trong nc ch c loi c n c - tc l loi thuc mc dinh dng th 2 th sinh khi cui cng s nhiu hn ng k.

7.2.3.2. Vai tr ca cc loi thy sinh trong qu trnh t lm sch ngun nc:

Vai tr ca cc loi thy sinh vt trong qu trnh phn hy cht bn hu c trong nc ngun c th tm tt nh sau:

- Thc vt ph du lm giu oxy trong nc. Oxy th cn cho qu trnh phn hy cht hu c, lm gim cc nguyn t dinh dng trong nc. Thc vt ph du l ngun thc n cho cc loi sinh vt n thc vt. Tuy nhin nu thc vt ph du pht trin qu mnh th li lm ngun nc b nhim bn ln th hai.

- Nhng loi thc vt ln cng lm giu oxy trong nc v lm gim lng cc cht dinh dng, tham gia tch cc vo vic kh cc sn phm du, cc cht c, d tch khi bn nc. nhng sng h t nc, chng d bin thnh m ly.

- Vi khun ng vai tr chnh trong qu trnh phn hy cc cht hu c, chng c kh nng phn hy bt k loi hp cht hu c no trong thin nhin, l ngun thc n cho cc sinh vt mc tip theo.

- ng vt ph du n thc vt v vi khun, ng thi cng tham gia qu trnh phn hy cc cht hu c. C th tch cc cht l lng v lm cho nc trong. Chng lm gim hm lng oxy trong nc do h hp cng nh do chng n thc vt ph du. Chng lm xo trn nc v hp th cc sinh vt gy bnh, c th kh trng trong nc.

- Cc loi ng vt ph du ln n thc vt ph du, tham gia qu trnh phn hy cht hu c - mc no cng nh hng ti ch oxy trong nc. C l tt nh ca cc mc dinh dng. Nhng loi c n thc vt s lm cn tr hin tng n hoa trong ngun nc v gy nh hng i vi thnh phn tt c cc loi thy sinh vt cc mc dinh dng khc nhau.

Mi quan h v thc n gia cc loi thy sinh vt rt phc tp , nn gp nhiu kh khn trong nghin cu. Vic tnh ton cc sn phm ca cc mc dinh dng rt cn thit, do mt mt ta hnh dung ngun thc n ca con ngi v c, mt khc xc nh s phn hy cht hu c trong ngun nc din ra ti mc no. Trong ngun nc s mc dinh dng cng nhiu th phn sn phm s cp nm trong sn phm cui cng cng t.

7.2.3.3. nh hng ca cc cht bn i vi nc ngun: Ty thuc s lng, thnh phn tnh cht ca mnh m cc cht bn c th gy ra

nhng hu qu khc nhau i vi nc ngun: - Lm thay i tnh cht ha l, trong, mu, mi, v, pH, hm lng cc cht

hu c, v c, xut hin cc cht c, cht ni, cht d lng cn...


232

- Lm gim hm lng oxy ha tan do phi tiu hao cho cc qu trnh oxy ha sinh ha cc cht bn hu c.

- Lm thay i s lng v cc chng loi vi sinh vt, sinh vt, xut hin cc loi vi sinh vt gy bnh, lm c cht... Kt qu khng th s dng lm ngun cung cp nc c.

Nhnh chung tt c nhng thay i c lin quan mt thit vi nhau. c bit cc cht bn trong nc thi sn xut l nhng cht c hi i vi thy sinh vt. Nng cc cht hu c qu cao s to iu kin ym kh trong nc, cc cht sulfure s lm gim kh nng oxy ha kh ca nc. Nu hm lng cc cht dinh dng trong nc ngun tng ln s dn n hin tng n hoa - pht trin ru to...

- nh hng c hi: Cc cht bn c hi c th gy tc ng khc nhau i vi thy sinh vt, ty thuc bn cht, nng ca chng. Mt cht c no c th ph hoi ch trao i cht hoc nhp sinh trng, pht trin ca thy sinh vt, ti mt gi tr nng no , chng s b tiu dit. i vi nhiu loi sinh vt, c th cha thy ngay tc ng c hi, m mi ch lm hng c quan sinh sn, hoc gy nh hng ti nhiu th h sau. Kt qu l s lng c th sinh vt, s loi s b gim dn...

Cc loi sinh vt c kh nng chu ng khc nhau i vi tng loi cht c. VD: As c th lm tm, Daphnia, Xiclop cht nng 0.25-2.5mg/l; i vi c: 10-2mg/l.

Trong thc t bo v v sinh ngun nc, ngi ta xc nh nng gii hn cho php ca tng cht c i vi vi sinh vt v sinh vt. Nng gii hn cho php lgi tr nng cao nht, vi gi tr , cc qu trnh khong ha cc cht hu c khng b ph hy, khng lm xu gi tr thc phm ca nc, khng gy c hi i vi qu trnh sng, hot ng ca thy sinh vt - nhng tc nhn quan trng trong qu trnh chuyn ha cht hu c. Nh vy nng gii hn cho php s m bo cho qu trnh sinh ha din ra bnh thng, m bo cho cht lng nc c tt, ng thi khng lm gim gi tr hng ha ca cc sinh vt.

- S thay i ch ha tan ca oxy trong nc ngun; lng vi khun v nm trong nc ty thuc nhiu yu t. Trong ngun nc sch thng khng cht hu c (cht dinh dng) cho cc loi hoi sinh. Khi cc cht hu c ln vo nc ngun th cc vi sinh vt pht trin nhy vt. Trong qu trnh sinh trng pht trin, cc vi sinh vt tiu th cng nhiu oxy. Kt qu nng oxy trong nc gim, thm ch b tiu th hon ton, lm thay i th nng oxy ha kh ca mi trng; cc phn ng kh din ra ch yu: kh nitrat, kh sulfat, hnh thnh cc cht sulfure v to iu kin ym kh trong mi trng. S thay i ch kh oxy ha tan s ko theo s thay i qun th sinh vt. Cc loi thch nghi vi nc sch trc y th by gi khi thiu oxy s b cht (u tin l c ri tip l nhng ng vt thng ng), ng thi cc loi qun th thch nghi vi iu kin thiu kh s pht trin, oxy ha cc cht hu c gim v trong nc ngun s tch ly sn phm khng b oxy ha hon ton.


233

- Nng oxy trong nc sng bn rt thp, 20oC ch khong 8mg/l (Hnh 7-5). Khi nhit tng ln, ha tan oxy li gim. Trong khi cng cc qu trnh oxy ha v tc tiu th oxy li tng ln v ngc li.

- Trong cc dng sng chy xit, do dng chy ri nn cc lp nc trn cng gn bin gii nc khng kh s ha tan c nhiu oxy. Khi khuy trn vi cc lp di t oxy th vic cung cp oxy cho vi sinh vt s c y (Hnh 7-6).

Hnh 7.5 Mi quan h gia nng trung ho tan v s vi khun cc vng khc nhau

Hnh 7.6 ho tan oxy trong nc cc vng nhit khc nhau


234

cc dng sng chy chm hoc cc h, cc lp nc trn cng c oxy ha

tan, nhng oxy ch khuch tn xung cc lp di vi lng t nn ni chung cc lp nc di thng to thnh iu kin ym kh.

- Nng cc cht dinh dng: S tiu th oxy l kt qu trc tip ca cc qu trnh trao i hiu kh ca vi sinh vt. Thng thng, cng qu trnh trao i cht cn b gii hn bi thiu cht dinh dng trong nc ngun. Nng cht hu c thp th ch cho php mt t vi khun v nm pht trin. Do hn ch s pht trin ng vt trong ngun.

Khi x nc thi vi cht hu c vo ngun, tc pht trin ca vi khun, nm cng tng ln. Kt qu li t l nghch vi nng oxy. Nu cht hu c qu nhiu, ngun oxy khng , s to iu kin ym kh. Nh vy tc trao i cht ca vi khun phi lun lun thp hn tc ha tan oxy vi nng gii hn ca cc cht dinh dng. Vi iu kin hiu kh, protozoa ko theo c cc ng vt thng ng cng pht trin. Nh vy nng oxy cng cao th cng nhiu ng vt c th tn ti

Hnh 7.7 S ho tan oxy trong dng chy

Hnh 7.8 S ho tan oxy trong dng chy chm


235

v cng c cung cp nhiu thc n. Cui cng, iu kin sinh ha tt nht nn duy tr sng l cung cp va , c gii hn cht dinh dng v t loi vi sinh vt..

Trong nc thi th thng cha nhiu lng nguyn t dinh dng (N, P). Nhng cht ny kch thch to pht trin rt mnh, sng h khng dng lm ngun cp nc c. To pht trin lm nc c mu, to xanh Aphanizomenon blos-aquae, Anabaena, microcystic v.v... lm nc c mu xanh lam; to xanh Oscilatoria rubecens lm nc ng mu hng; Aphanocapsa pulchre to mt lp vng en trn mt nc. To lc lm nc c mu lc, khu to (Melosira, Navicula) lm nc c mu vng nu; Chrisophit lm nc c mu vng vng.

To pht trin cn lm cho nc c mi v kh chu, nh mi c, mi m kht, thi Ngoi ra cn gy tc c hc cc li chn ca cng trnh thu nc, cc b lc ca nh my nc. Hin tng trn cn gi l hin tng n hoa (Eutrofication).Khi to cht s gy thi ra trong nc, vi sinh vt oxy ha cc cht hu c v tiu th oxy lm oxy ha tan b ngho i. Theo tnh ton ca D.Ulman, oxy ha lng cht bn hu c do 1 ngi thi ra, cn 80g oxy trong mt ngy, cn oxy ha cht hu c ca to (to pht trin do phospho trong nc thi tnh theo 1 ngi) i hi ti 320g O2. V vy ngi ta phi kh N, P trc khi x nc thi ra ngun v phi tm bin php chng n hoa trong nc ngun.

nh hng ca cc cht lng cn v cc cht ni: Nc ma, nc thi sinh hot, cng nghip, nc tiu t cc h thng thy li, cha rt nhiu cht l lng v l cy. Khi ra ti sng h, tc dng chy gim. Kt qu gy lng cn y sng h, lm thay i hnh dng dng sng. Nhng cht hu c lng cn l i tng hot ng pht trin vi sinh vt . Kt qu cng lm gim lng oxy ha tan, gy thi ra tiu dit thy sinh vt. Cc cht ni nh du m cha nhiu trong nc thi sinh hot, cng nghip cng lm hn ch oxy ha tan.

7.2.4. Phn loi ngun nc theo mc nhim bn: Cht lng nc ngun c nh gi trn c s cc s liu phn tch ha l, vi

sinh vt. Mi dng phn tch u c u nhc im nht nh v khng thay th nhau c. nh gi tt nht th nn c c 3 dng phn tch trn.

Cc ch tiu phn tch ha hc cho php nh gi v lng v c tnh cc cht bn, nh hng ca chng i vi s thay i cht lng nc ngun. Cc ch tiu phn tch vi sinh vt cho php xc nh sc xut tn ti trong nc ca cc loi vi sinh vt gy bnh. Phn tch sinh vt gip xc nh mc bn ca nc trn ton cc din, nhiu khi cng cho php xc nh hu qu ca s nhim bn t xut m cc phng php nghin cu ha l, vi sinh vt cha th thc hin kp thi ngay c.

Phn tch sinh vt l da trn s thch ng ca mt s sinh vt i vi nc c cht lng nht nh.

Do kh nng t lm sch ca ngun nc, cc cht bn ln vo s c pha long v b phn hy. S phn hy cht bn din ra dn dn v do vy cc iu kin bnh thng ca ngun nc cng dn dn c phc hi tr li nh trc khi c cht bn (nc thi) x vo. Qu trnh ny l mt qu trnh lu di v vng nhim bn ca sng c th ko di hng chc, hng trm cy s. Quy m ca vng ny ty thuc vo


236

t l gia lng nc thi v nc sng , nng & tnh cht cc cht bn, tc dng chy v nhiu yu t khc.

Ty thuc bn ca nc m ngi ta chia cc sng, h v cc on sng thnh cc vng sau y (xem bng 7-2):

Bng 7-2: Phn loi cc on sng theo nhim bn (theo R.Kolvints, M.Marson, G.Lipman)

Vng hoi sinh (Theo R.Kolvints v M.Marson)

Mc sch (Theo G.Lipman)

- Polixaprophit, k hiu : P

- Alpha-Mezoxaprophit, k hiu : -m

- Beta-Mezoxaprophit, k hiu : -m

- Oligoxaprophit, k hiu : O

IV III II I

Khi ngun nc b nhim bn th iu kin ha l ca n b thay i, mt s loi

thy sinh vt pht trin, mt s loi b tiu dit - tc l cc qun th b thay i. Nhiu sinh vt ch thch ng vi cc iu kin cht lng nht nh, tc l ch sng nhng vng nhim bn nht nh.

- Vng P: Hm lng cc cht hu c khng bn vng kh cao, nhiu sn phm phn hy ym kh. Trong nc nhiu cht m protein. NOS ti hng chc mg/l. Khng c quang hp. Oxy ch c th hatan trong nc qua mt thong v tiu th ngay cho vic oxy ha cc lp nc trn mt cho nn thc t trong nc khng c oxy. Nc cha CH4 v H2S. vng ny cha rt nhiu vi sinh vt hoi sinh, ti hng trm ngn hoc hng triu t bo trong 1ml. cn y khng c oxy, cha nhiu detrit, din ra cc qu trnh kh st dng FeS: bn c mu en, mi tanh H2S. vng ny pht trin nhiu sinh thc vt dng d dng: cc loi vi khun (k c vi khun dng ch Sphaerotilus), vi khun lu hunh (Beggiatoathiopthrix), vi khun dng nhy (Zoogleea ramigera), cc loi vi khun h ng trch trng tin mao.

- Vng -m: vng ny bt u din ra s phn hy hiu kh cc cc cht hu c & to ra amoniac, cha nhiu CO2 t do, mt t oxy, khng c metan v H2S. Lng cht bn theo NOS vn cn cao ti hng chc mg/l. Lng vi khun hoi sinh ti hng chc, hng trm ngn t bo trong 1ml.

Trong nc v cn lng y din ra cc qu trnh oxy ha kh. St dng oxyt v dioxyt (Fe2+ v Fe3+), bn xm mu en. vng -m c cc loi vi sinh vt chu c iu kin thiu oxy v nhiu CO2. C cc loi thc vt d dng v x khun. Pht trin nhiu loi vi khun dng nhy, dng ch, nm; c cc loi to: Oscilatori stigeochlonium.


237

Trong s cc ng vt, pht trin nhiu l loi trch trng (Carchesium), c loi lun trng Rotatoria brachionus v nhiu loi c tin mao - gi tc. Trong bn nhiu turbiphycid v b Chironomid.

- Vng -m: L nhng vng hu nh khng c cht hu c, tc l phn hy (khong ha) hon ton. Lng vi khun hoi sinh ti hng ngn t bo trong 1ml v tng nhanh vo thi k thc vt nc b cht. Nng oxy rt cao v CO2 dao ng mnh trong sut ngy m. Ban ngy lng oxy rt cao v c th ti bo ha, CO2 hon ton khng c, v m li thy thiu ht oxy. Trong bn c nhiu detrit v qu trnh oxy ha din ra rt mnh. Bn mu vng. vng ny c nhiu ng thc vt khc nhau. Cc loi thc vt t dinh pht trin mnh. Hin tng n hoa - thc vt ph sinh xut hin, pht trin: cc loi to xanh dng ch, khu to apirit. Trong bn c giun, b, chironomit, nhuyn th.

- Vng O: L vng nc sch, lng cht hu c khng ng k v lng cc sn phm khong ha cng t. Hm lng CO2 v oxy n nh, t dao ng c ban ngy ln ban m. Khng thy xut hin hin tng n hoa. Cn lng di y cng cha t detrit, cc vi sinh vt t dinh v ng vt y (giun, b chironomid v nhuyn th). Du hiu chng t nc rt sch v c 1 t to hng (thoria, Batrachospermum) v b nc (Mchi).

Cc loi sinh vt ch th ring bit khng nh gi nhim bn ca nc. Chng hn khi phn hy protit ca nc thi sinh hot s to ra nhiu sulfure, nn c nhiu vi khun lu hunh loi Beggiatoa v thiothrix. Trong khi nhng vi khun ny cng c th sng nhng ngun nc khong c lu hunh m khng cha cc cht bn hu c. Vi khun lu hunh l ch th c lu hunh trong nc nhng khng cho bit xut x ca lu hunh - hu c hay v c. V vy khi nh gi mc bn ca ngun nc, ch c th cn c theo cc qun th c trng i vi tng vng hoi sinh ch khng phi theo tng loi ring bit.

Ngy nay c nhiu kiu phn loi ngun nc theo bn. VD: ngi ta phn ra 6 nhm ngun nc theo bng 7-3:

Bng 7-3: Ch tiu ha hc v vi trng hc v mc nhim bn ca cc loi ngun nc.

Ch tiu ha hc, mg/l Ch tiu vi trng hc

Oxy ha tan

Mc bn

H ng

L lng NOS5

oxy ha

Nit amn Coli titre, ml

S vi khun

m trc

tip s v.k

Rt sch

Sch

Hi bn

Bn va

Bn

Rt bn

9

8

7-6

5-4

3-2

0

14-13

12-11

10-9

5-4

5-1-0

0

1-3

4-10

11-19

20-50

51-100

>100

0.5-1

1.1-1.9

2-2.9

3-3.9

4-10

>10

1

2

3

4

5-15

>15

0.05

0.1

0.2-0.3

0.4-1

1.1-3

>3

10-100

10-1

1-0.05

0.05-0.005

0.005-0.001

a.101

a.102

a.103

a.104

a.105

0.001

105

106

106

107

107

a.10P


238

nhng ngun nc rt sch th hon ton khng thy du vt tc ng ca con

ngi. , bo ha oxy ti 95%, NOS5 khng qu 1mg/l, cht l lng 3mg/l. Ngun ny dng cho tt c cc i tng cp nc.

Nhng ngun nc sch v cc ch tiu ha hc khng khc lm so vi nhng ngun nc rt sch nhng thy du vt hot ng ca con ngi - c th l lng vi khun hoi sinh tng ln. Ngun ny cng dng cho cc i tng cp nc. kh trng ch cn chlore ha l .

Ngun nc hi bn, hm lng cht hu c tng ln, c ion chlore v amon. l du hiu nhim bn bi nc ma trn mt t, nc thi sinh hot chy xung. Nc hi bn phi c x l thch ng mi c dng cp nc sinh hot dn dng. Nc ny c th dng nui c hoc cc mc tiu khc.

Loi ngun nc bn va l nhng sng h b thay i tnh cht t nhin do c nc thi chy vo. Ma ng c th to iu kin ym kh trong h nhng vng x lnh, v b bao ph bi lp bng trn mt. Nc ny khng dng cp nc sinh hot c, cng khng dng cho mc ch vn ha th thao, nui c. Phm vi s dng ngun nc ny rt b hn ch, ch dng cho 1 s qu trnh sn xut hoc ti tiu, giao thng ng thy.

Ngun nc bn v rt bn: hon ton mt tnh cht t nhin. Ma h xng mi kh chu. Trong nc cha nhiu CO2, cc hp cht sulfure, chng t do hot ng ca tu b, cng. Do vy ngun nc ny ch dng cho giao thng tu b. Cn vic dng ti rung cng b hn ch v khng thch hp vi nhiu loi cy trng.

Khi nh gi bn ca ngun nc, trc khi phn tch ha hc, nhiu khi cc ch tiu: mu, mi, trong, c cng l cc du hiu quan trng chng t s c mt ca nhiu cht bn. VD: mi cc cht c x vo nh phenon, dichloretan, orezon, du Du ln vo chng nhng c mi m cn c vng ni ln.

7.3. CC QU TRNH VI SINH VT TRONG CC CNG TRNH X L NC THIN NHIN

Cc qu trnh vi sinh ha din ra khi x l nc thin nhin khng phc tp nh khi x l nc thi v cc cht hu c trong nc thin nhin t hn nhiu c v lng tng cht cng nh c v s loi cht. Nc ngm cha t cht bn v vi sinh vt hn so vi nc mt. Nc mt cha cc cht bn nh cht l lng, mu, cht hu c, v c, vi khun v nhiu loi vi sinh vt khc. Nhng cht bn phi c loi tr trc khi a n ngi s dng. Cc loi cng trnh x l ty thuc c tnh nc th. Chng hn nc cha cc cht khng tan d lng th c th cho lng cc b lng loi cc cht ; nc c mu v cha cc cht keo, phi x l bng cch cho keo t ri lng v lc sau . Nc cng phi c lm mm; nc cha mui th phi kh mui; nc cha st th phi kh st. Nu nc cha nhiu loi cht bn v vi khun th phi x l rt phc tp. Nhn chung khi x l nc thin nhin, vi sinh vt tham gia ch yu vo cc qu trnh lng v lc.


239

7.3.1. Lng: Mt trong nhng phng php n gin nht x l nc thin nhin l lng.

Khi lng, nhng ht l lng nng s lng xung. Vi khun hp ph v dnh vo cc ht cng dnh v lng theo. Kt qu nng cc cht l lng, lng nit amn, vi khun gim i rt nhiu, thm ch trong mt s trng hp gim c c mu.

C th thc hin vic lng nc trong cc h ln - gi l h s lng. Vi thi gian, nc lu li trong 5-7 ngy th lng vi khun ng rut gim ti 90%. Tuy nhin cn 10% chng vn c th tn ti c my tun hoc hng thng. Khong thi gian ny ty thuc mc trong sch ca nc. Nc cng bn th vi khun gy bnh cng chng cht, v s c s i khng cnh tranh gia nhng loi vi sinh vt.

Khi s lng trong my ngy u s din ra qu trnh t lm sch. Tuy nhin, thi gian s lng cng ko di th s din ra qu trnh ngc li, cht lng ca nc s km i, v s pht hin v pht trin to ru, nng lng ca nh sng mt tri s bin thnh sinh khi ca chng v khi chng cht s lm nng cht hu c tng ln, xut hin vi sinh vt thi ra, nc s c mi v xu, gim lng oxy ha tan, th nng oxy ha b gim. Kt qu s gy kh khn cho vic x l tip theo. chng s pht trin to (n hoa) trong cc h lng, ngi ta dng cc bin php nh: th c, che ti b, dng cc alhycide.

Trong thc t, ngi ta thng li dng a hnh t nhin, chng hn cc vnh cnh b sng lm h s lng th s rt kinh t. Trong cng ngh x l nc thin nhin ngi ta xy dng nhiu loi b lng khc nhau vi thi gian lng khc nhau ty thuc cht lng nc, cc yu cu kinh t - k thut v cng ngh. tt c cc loi h, b lng, thng thy nhiu loi thc vt ph du v nhiu to xanh lam, khu to to thnh mng mng gi l ru. Trn cc mng mng, ru li c c cc loi ng vt ph du. Ngoi ra cn phi thy rng cc b lng cn din ra nhng qu trnh sinh ha lin quan n vic phn gii cc cht hu c trong iu kin ym kh.

7.3.2. Lc nc: B lc chm: Trong s cc cng trnh x l nc thin nhin th b lc chm l

cng trnh lin quan nhiu nht ti vi sinh vt. Ngay t u khi sng to ra loi cng trnh ny, ngi ta mun ti to cc qu trnh sinh ha t nhin ging nh khi cho nc thm lc qua t. Nhng khng nhng ch n thun ti to nhng iu kin t nhin , m ngi ta cn xy dng nhng cng trnh nhm ci thin iu kin t nhin theo hng c li hn na.

Lp trn cng ca vt liu lc l lp ct ht nh. s gi li cc ht cht bn v hnh thnh nhng qun lc sinh vt, din ra cc qu trnh sinh hc v lm sch nc. Nhng qun lc bao gm nhiu nht l nhng vi sinh vt khong ha (oxy ha nit ca mui amn thnh nitrit, ri nitrat, H2S thnh mui sulfat) v mt t ng thc vt ph du. Tt c nhng qun lc sinh vt s to nn mng sinh vt dy c. Tuy nhin chiu dy ca lp ct c mng sinh vt ny ch vi cm m thi v nhng vi sinh vt ny ch yu l loi hiu kh nn sng trn b mt b lc. Nhng yu t nh hng ti hiu qu cng tc ca b l: nhit , vn tc, kch thc ht. Nu ht ct qu nh th b nhanh chng b tc; nu ht qu ln th khng gi c cc cht l lng mng sinh vt m i theo nc lc.


240

Kch thc ht lp lc thng 0.2 0.4mm. V ht rt nh nn lp trn cng chng b vt tc v khong t 2-10 tun phi xc lp ra hoc thay mi. Tc lc ty thuc cht lng nc v thng chn 0.1-0.3m/h.

Nhit l yu t ch yu nh hng ti qu trnh lm sch nc v tc nhn hot ng ch yu y l qun lc sinh vt. Hiu qu lm sch nc ca b lc rt tt, hn 99.99% vi khun b gi li. Tc chm i hi din tch b lc rt ln nn ngy nay ngi ta thng t dng b ny. Ngoi ra v ma h, nc sng, h cha thng c to v lm lp ct lc chng b tc.

B lc nhanh: y ch yu din ra qu trnh vt l, ha v ha l. i khi ch gp mt vi hin tng sinh ha m thi. Chng hn khi thi tit m, nit amn b kh, trong nc lc, lng nitrit, nitrat tng ln.

Kh cc cht phng x bng cch lc nc: Vi sinh vt nc ni chung v qun lc sinh vt b lc ni ring l tc nhn c th hp ph cc cht phng x. Do hiu sut kh cc cht phng x ca b lc rt tt. Ty thuc tng loi cht v nng ca cc cht trong nc, hiu sut kh cc cht phng x c th t t 50-96%.

7.3.3. X l nc bng ha cht: Keo t bng phn nhm hoc st l mt trong nhng phng php ph bin

x l nc. Trong nc thin nhin cha nhiu loi ht keo dng vi khun, t st hoc hu c. Nhng ion nhm c in tch dng mnh, cn a s cc ht keo c in tch m. Vi gi tr pH thch hp chng s hp ph ri keo t vi nhau v to thnh bng cn kt ta. nhng iu kin tnh, bng cn s lng v ko theo c nhng vi khun. hiu sut kh vi khun khi keo t ty thuc loi b phn ng v b lng, c th t 90-99%.

7.3.4. Kh trng nc: Giai on kt thc ca vic x l nc thin nhin l kh trng. Nh ta bit,

tng hiu sut kh trng, trc ngi ta phi loi tr cc cht bn hu c, v c trong nc (ch tr mt s loi nc ngm rt sch, khng cn x l mi thc hin kh trng trc tip m thi). V vy ngi ta thng kh trng sau khi nc ra khi b lc, trc khi vo b cha. Trong b cha nc sch, chlore s gy phn ng git cht vi khun.

Nhng bin php kh trng thng thng ch nhm dit cc loi vi khun khng to nha bo v cc loi vi khun lin quan n ng truyn bnh qua nc u l nhng loi khng to nha bo.

Ngi ta phn bit cc bin php kh trng c th v tp trung. Cc bin php c th nh: un si, dng thuc vin st trng, dng nc bc (ion bc). Cc bin php tp trung: kh trng bng chlore v cc bin php khc.

Theo Chick, khi dng mt tc nhn vt l hay ha hc no kh trng th t l % gia lng vi khun cn sng st vi s vi khun ban u l mt i lng khng i v c biu th bng cng thc:

2

1lg1NN

tK = (X-I)


241

K - tc cht ca vi khun; t - thi gian tc ng ca tc nhn dit trng; N1 - Nng vi khun ban u; N2 - Nng vi khun cn sng st; ngha thc tin ca nh lut Chick l ch: Kt qu kh trng lun lun ty

thuc mc nhim khun ca nc. Chng hn, cng l 99% vi khun b tiu dit, nhng nu lng vi khun ban u l 100 th cn sng 1 vi khun, nu lng vi khun ban u l 10,000 th cn sng 100 c th. Nh vy, nu ni hiu sut dit trng u tt nh trng hp sau th cn xa mi an ton.

7.3.4.1. Kh trng nc bng chlore: a. C ch dit trng ca chlore trong nc : - Khi chlore ha, do tng th nng oxy ha, lm nguyn sinh cht ca t bo b

oxy ha. - Tc dng oxy ha bi oxy to ra: Khi chlore ha, chlore tc dng vi ncto

thnh hypoclor (HClO). Acid ny khng bn vng nn to ra oxy nguyn t v oxy ha t bo ca vi khun. Phn ng din ra nh sau:

Cl2 + H2O 2HClO (X-2)

HClO HCl + (X-3) - Acid hypoclor cng c th phn ly:

HClO H+ + ClO- (X-4) Ion ClO- cng c kh nng gy oxy ha t bo cht. Nhng theo Rose E.Mackiney th dng khng phn ly HClO c hot tnh mnh

hn nhiu so vi dng phn ly. Thc nghim cho thy hiu sut kh trng pH = 7 cao hn gi tr pH = 9. iu , theo R. E.Mackiney l do khi pH tng ln th dng phn ly s tng v hiu sut kh trng gim.

- Tc dng trc tip ca chlore: Bn thn chlore cng tc dng trc tip vi t bo vi khun, v chlore lin kt vi cc cht trong thnh phn t bo v lm vi khun cht.

- Tc ng bi tia cc tm: Do c phn ng ha hc xy ra gia chlore v cc cht hu c trong nc nn xut hin cc tia t ngoi v git cht vi khun.

Ni chung, kh trng bng chlore rt hiu qu v n to ra gc oxy ha lm gim h thng men ngn cn qu trnh h hp bnh thng ca vi khun.

b. Cc yu t nh hng ti hiu qu kh trng ca chlore: - Trong nc thin nhin thng cha cc cht d b oxy ha. Do khi cho

chlore - mt cht oxy ha mnh vo nc th n s tc dng mnh vi cc cht trong nc. Cc cht d b oxy ha trong nc c th l cht hu c (nh humus tan trong nc, cc sn phm phn hy protein, m, ng, nitrat, mui st ha tr 2, H2S).


242

Lng cc cht ny trong nc cnh nhiu th lng chlore tiu th oxy ha cc cht cng cng nhiu. Ta gi l mc hp th chlore ca nc.

Lng chlore tiu th cho t hp tt c cc phn ng ph thuc nhiu yu t: liu lng chlore cho vo ban u, thi gian tip xc, th nng oxy ha, nng ion hydro, nhit

nhng iu kin nht nh th hiu sut kh trng ca chlore ph thuc liu lng chlore cho vo nc, thi gian chlore t do tn ti trong nc, pH, nhit , lng vi khun

Liu lng chlore cn thit kh trng bao gm: lng chlore tiu th v lng chlore git cht vi khun. Trong thc t c th coi rng: t c hiu qu kh trng, nng chlore d cn li trong nc sau 1/2h tip xc phi khng di 0.1-0.33mg/l.

- nh hng ca liu lng chlore: Lng chlore d tn ti trong nc ty thuc lng chlore cho vo lc u. Mt khc liu lng chlore ban u cng cao th tc git cht vi khun cng cng mnh.

- nh hng ca thi gian tip xc: Nu thi gian tip xc cng lu, tc l b cha cng ln th liu lng chlore cn thit dit trng c th gim rt nhiu so vi b cha nh. Nhng cn thy rng thi gian tip xc cng lu th lng chlore d cng gim.

- nh hng ca nhit : Nhit nh hng ti tt c cc phn ng ha hc v c n qu trnh kh trng bng chlore. nhit thp 0oC th tc phn ng rt chm. Khi nhit tng th tc dit khun tng rt nhanh. C mi ln tng 100C th tc dit khun tng ln 2 ln. Tuy nhin nu nhit tng ln th lng chlore d cng nhanh chng b mt i.

- nh hng ca amoniac: Khi cho amoniac vo nc th s gim c lng chlore tiu th trong qu trnh kh trng. V khi cho amoniac vo nc th hin tng phn hy chlore do quang ha s chm dt ngay. Tuy nhin mt s nh nghin cu cho rng khi s to thnh chlore-amin. Cht ny c th nng oxy ha rt thp v lm hot tnh ca chlore b gim. Mt s kin khc li cho rng amoniac s tc dng vi cc cht hu c, v c trong nc v nhng cht ny s khng b oxy ha bi chlore na.

c. Tc dng ca vic kh trng bng chlore: - Kh trng bng chlore khng c: Chlore l mt cht c. Sau khi kh trng,

trong nc vn cn mt lng chlore nht nh. Nhng Trerkinski v nhiu ngi khc cho thy: nng chlore t do trong nc l 0.3-0.5mg/l th hon ton khng c vi c th ngi. Vi nng , ngi ta li thy ngon v thm mt hn.

- Dng chlore kh mi v ca nc: Chlore l cht oxy ha mnh, do i khi ngi ta dng n kh mi (nht l mi H2S) v v ca nc. Trong nhng trng hp ny, trong nc thng cn li mt lng chlore kh ln v ngi ta li phi kh lng chlore ny. Mun vy ngi ta phi cho mt lng cht no vo nc lin kt vi chlore nhng khng to thnh cht c i vi c th. Nhng cht


243

thng dng kh chlore: hyposulfit, sulfat natri, kh sulfure, chlore st, than hot tnh.

- Kh trng trn mng li cp nc: Trc khi s dng ng ng dn nc hoc khi ng dn nc b nhim trng gy bnh th ngi ta phi tin hnh kh trng i nc v ng dn vi liu lng chlore cao. Liu lng chlore cn thit l 30-50 mg/l theo chlore t do vi thi gian chlore ha l 24h hoc 80-100 mg/l chlore t do vi thi gian 8h.

trnh c bi chlore cho ngi dng, trc khi kh trng phi bo trc h m kha x nc i, khng s dng na.

7.3.4.2. Kh trng bng cc phng php khc: a. Phng php vt l: C nhng u im l: khng cho thm ho cht no vo

nc tc l khng lm nc c mi v g khc; khng cn duy tr mt lng d ca cht kh trng nn khng hi cho c th ngi; khng cn nhng thit b phc tp nh lng nn khng cn th nghim kim tra; khng cn b tip xc v cc tc nhn vt l c th dit trng ngay tc khc; khng phi chuyn ch ha cht, khng cn kho nn trm x l rt nh. Cc phng php vt l bao gm:

- Sng siu m: Khi sng siu m tc nh vo cht lng th s din ra hin tng p mnh v ct nc. Lc tc ng ca cc sng rt mnh n ni to ra hin tng kh thc trong nc v to ra p sut rt ln ti hng ngn tmtphe, tc khc t bo vi khun b n tung. Vi khun cng gn cc bt kh thc, cng b va p mnh. Tc dng kh trng s b gim t l nghch vi bnh phng khong cch t vi khun ti bt kh. Khi cng siu m ca my pht sng l 0,3 0,5 w/cm2 th s to ra hin tng kh thc. Tt nhin trong nc cng to nhiu bt kh th hiu sut kh trng cng cao. Mt khc nht ca nc cng cao th cng kh to thnh kh thc v hiu sut kh trng cng thp. Hnh dng vi khun trong nc s nh hng ti hiu sut kh trng.Cu khun bn vng nht v trc khun chng b tiu dit nht. Nhng khi tng cng sng siu m th c cu khun ln trc khun u cht, c vi khun to v khng to nha bo cng cht. Sng siu m dit c trng c trong nc c, nc cha bn.

- Tia t ngoi: Tia t ngoi nm trong khong sng t 136 4000 Ao. Khi chiu tia t ngoi qua nc s lm vi khun cht ngay v tia t ngoi c tc dng quang ha; thnh phn ca nc hon ton khng thay i. Nhng gi tr pH thay i rt nhiu v nhit nc cng tng, nh hng ti hiu sut kh trng. Tia t ngoi ch c th xuyn qua

phẦn ii vsv vÀ cÁc quÁ trÌnh sinh hỌc trong …moitruong.com.vn/upload/48/nam_2013/thu vien...

Documents