Cac Yeu to Danh Gia Chat Luong Nuoc

8/7/2019 Cac Yeu to Danh Gia Chat Luong Nuoc

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1. Mi v

- Nc ging ngm: mi trng thi l do c kh H2S, kt qu ca qu trnh phn

hy cc cht hu c trong lng t v ha tan vo mch nc ngm. Mi tanh ca

st v mangan.

- Nc mt (sng, sui, ao h): mi tanh ca to l do s xut hin ca cc loi tov vi sinh vt. Trong trng hp ny nc thng c mu xanh.

- Nc my: mi ha cht kh trng (clo) cn d li trong nc.

Mi v khc l s gy cm gic kh chu khi dng nc. Tu theo loi mi v m

c cch x l ph hp nh dng ha cht dit to trong ao h, keo t lng lc, hp

ph bng than hot tnh,

2. Mu

- Mu vng ca hp cht st v mangan.

- Mu xanh ca to, hp cht hu c.

Nc c mu cao thng gy kh chu v mt cm quan. Vi cc quy trnh x

l nh sc kh ozn, clo ha s b, keo t, lng lc c th lm gim mu ca

nc. Cn lu , khi ngun nc c mu do hp cht hu c, vic s dng Clo c

th to ra cht mi l trihalomethane c kh nng gy ung th. Tiu chun nc

sinh hot quy nh mu ca nc < 15 TCU.

3. pH

Ngun nc c pH > 7 thng cha nhiu ion nhm carbonate v bicarbonate (do

chy qua nhiu tng t ). Ngun nc c pH < 7 thng cha nhiu ion gc

axit.

Ngoi vic pH thp c th gy h men rng, cha c bng chng c th no lin

quan gia pH v sc khe ca ngi s dng. Theo Tiu chun, pH ca nc

s dng cho sinh hot l 6,0 8,5 v ca nc ung l 6,5 8,5. Tuy nhin, cc

loi nc ngt c gas c pH t 2,0 4,0. Cc loi thc phm thng c pH =

2,9 3,3. Gi tr pH ca nc c lin quan n tnh n mn thit b, ng ng

dn nc v dng c cha nc. c bit, trong mi trng pH thp, kh nng

kh trng ca Clo s mnh hn. Tuy nhin, khi pH > 8,5 nu trong nc c hp

cht hu c th vic kh trng bng Clo d to thnh hp cht trihalomethane gy

ung th.

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4. c

c l i lng o hm lng cht l lng trong nc, thng do s hin din

ca cht keo, st, to v vi sinh vt.

Nc c gy cm gic kh chu v mt cm quan, ngoi ra cn c kh nngnhim vi sinh. Tiu chun nc sch quy nh c nh hn 5NTU, nhng gii

hn ti a ca nc ung ch l 2 NTU. Cc quy trnh x l nh keo t, lng, lc

gp phn lm gim c ca nc.

5. kim

kim ca nc l do cc ion bicarbonate, carbonate v hydroxide to nn.

Trong thnh phn ha hc ca nc, kim c lin quan n cc ch tiu khc

nh pH, cng v tng hm lng khong. Vic xc nh kim ca nc gip

cho vic nh lng ha cht trong qu trnh keo t, lm mm nc cng nh x

l chng n mn.

Hin nay, khng c bng chng c th no lin quan gia kim v sc khe ca

ngi s dng. Thng thng, nc dng cho n ung nn c kim thp hn

100 mg/l.

6. cng

cng l i lng o tng cc cation a ha tr c trong nc, nhiu nht l ion

canxi v magi. Nc mt thng khng c cng cao nh nc ngm. Hin

nay, ty theo cng ca nc ngi ta chia thnh cc loi sau:

cng = 0 50mg/l -> Nc mm

cng = 50 150mg/l -> Nc hi cng

cng = 150 300mg/l -> Nc cng

cng > 300mg/l -> Nc rt cng

Nc cng thng cn nhiu x phng hn to bt, hoc gy hin tng ng

cn trng trong thit b un, ng dn nc nng, thit b gii nhit hay l hi.

Ngc li, nc cng thng khng gy hin tng n mn ng ng v thit

b.Theo tiu chun nc sch, cng c quy nh nh hn 350 mg/l. i vi

nc n ung, cng nh hn 300 mg/l. Tuy nhin, khi cng vt qu 50

mg/l, trong cc thit b un nu xut hin cn trng. Trong thnh phn ca

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cng, canxi v magi l 2 yu t quan trng thng c b sung cho c th qua

ng thc n. Ch ngoi tr cc chng bnh v si thn cn hn ch vic hp th

canxi v magi hm lng cao. C th kh cng bng phng php trao i

ion. Sau mi chu k lc, ht nha cation c ti sinh bng dung dch mui n.

7. Tng cht rn ha tan (TDS)

TDS l i lng o tng cht rn ha tan c trong nc, hay cn gi l tng cht

khong.

Tiu chun nc sch quy nh TDS nh hn 1.200 mg/l. Tiu chun nc ung

quy nh TDS nh hn 1.000 mg/l.

8. oxy ha (Cht hu c)

oxy ha c dng nh gi mc nhim ca ngun nc. C 2 phng

php xc nh oxy ha ty theo ha cht s dng l phng php KMnO4 v

K2CrO7.

Tiu chun nc sch quy nh oxy ha theo KMnO4 nh hn 4 mg/l. Tiu

chun nc ung quy nh oxy ha (theo KMnO4) nh hn 2 mg/l.

9. Nhm

Nhm l thnh phn chnh trong cc loi khong, t st. Nhm c dng

trong cc ngnh cng nghip sn xut cht bn dn, thuc nhum, sn v c bit

l ha cht keo t trong x l nc. Nc khai thc t vng t nhim phn

thng c pH thp v hm lng nhm cao.

Nhm khng gy ri lon c ch trao i cht, tuy nhin c lin quan n cc

bnh Alzheimei v gia tng qu trnh lo ha. Tiu chun nc ung quy nh hm

lng nhm nh hn 0,2 mg/l.

10. St

Do ion st hai d b oxy ha thnh hydroxyt st ba, t kt ta v lng nn st t tn

ti trong ngun nc mt. i vi nc ngm, trong iu kin thiu kh, st

thng tn ti dng ion Fe2+ v ho tan trong nc. Khi c lm thong, st

hai s chuyn ha thnh st ba, xut hin kt ta hydroxyt st ba c mu vng, d

lng. Trong trng hp ngun nc c nhiu cht hu c, st c th tn ti dng

keo (phc hu c) rt kh x l. Ngoi ra, khi nc c pH thp, s gy hin

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tng n mn ng ng v dng c cha, lm tng hm lng st trong nc.

St khng gy c hi cho c th. Khi hm lng st cao s lm cho nc c v

tanh, mu vng, c v mu tng nn kh s dng. Tiu chun nc ung

v nc sch u quy nh hm lng st nh hn 0,5 mg/l.

11. Mangan

Mangan thng tn ti trong nc cng vi st nhng vi hm lng t hn. Khi

trong nc c mangan thng to lp cn mu en ng bm vo thnh v y

bn cha.

Mangan c c tnh rt thp v khng gy ung th. hm lng cao hn 0,15

mg/l c th to ra v kh chu, lm hoen qun o. Tiu chun nc ung v nc

sch u quy nh hm lng mangan nh hn 0,5 mg/l.

12. Asen (thch tn)

Do thm qua nhiu tng a cht khc nhau, nc ngm thng cha asen nhiu

hn nc mt. Ngoi ra asen c mt trong ngun nc khi b nhim nc thi

cng nghip, thuc tr su.

Khi b nhim asen, c kh nng gy ung th da v phi. Tiu chun nc sch quy

nh asen nh hn 0,05 mg/l. Tiu chun nc ung quy nh asen nh hn 0,01

mg/l.

13. Cadimi

Do thm qua nhiu tng a cht khc nhau, nc ngm thng cha hm lng

cadimi nhiu hn nc mt. Ngoi ra Cadimi c mt trong ngun nc khi b

nhim nc thi cng nghip khai thc m, nc r bi rc. Cadimi c th xut

hin trong ng ng thp trng km nu xy ra hin tng n mn.

Cadimi c tc ng xu n thn. Khi b nhim c cao c kh nng gy i ma.

Tiu chun nc ung quy nh Cadimi nh hn 0,003 mg/l.

14. Crm

Crm c mt trong ngun nc khi b nhim nc thi cng nghip khai thc m,

xi m, thuc da, thuc nhum, sn xut giy v gm s.

Crm ha tr 6 c c tnh mnh hn Crm ha tr 3 v tc ng xu n cc b

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phn c th nh gan, thn, c quan h hp. Nhim c cp tnh c th gy xut

huyt, vim da, u nht. Crm c xp vo cht c nhm 1 (c kh nng gy ung

th cho ngi v vt nui). Tiu chun nc ung quy nh crm nh hn 0,05

mg/l.

15. ng

ng hin din trong nc do hin tng n mn trn ng ng v cc dng c

thit b lm bng ng hoc ng thau. Cc loi ha cht dit to c s dng

rng ri trn ao h cng lm tng hm lng ng trong ngun nc. Nc thi t

nh my luyn kim, xi m, thuc da, sn xut thuc tr su, dit c hay phim nh

cng gp phn lm tng lng ng trong ngun nc.

ng khng tch ly trong c th nhiu n mc gy c. hm lng 1 2 mg/l

lm cho nc c v kh chu, v khng th ung c khi nng cao t 5 8

mg/l. Tiu chun nc ung v nc sch u quy nh hm lng ng nh hn

2 mg/l.

16. Ch

Trong ngun nc thin nhin ch pht hin hm lng ch 0,4 0,8 mg/l. Tuy

nhin do nhim nc thi cng nghip hoc hin tng n mn ng ng nn

c th pht hin ch trong nc ung mc cao hn.

Khi hm lng ch trong mu cao c th gy tn thng no, ri lon tiu ha, yu

c, ph hy hng cu. Ch c th tch ly trong c th n mc cao v gy c.

Tiu chun nc ung v nc sch u quy nh hm lng ch nh hn 0,01

mg/l.

17. Km

Km t khi c trong nc, ngoi tr b nhim t ngun nc thi ca cc khu

khai thc qung.

Cha pht hin km gy c cho c th ngi, nhng hm lng > 5 mg/l

lm cho nc c mu trng sa. Tiu chun nc ung v nc sch u quy nh

hm lng km < 3mg/l.

18. Niken

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Niken t khi hin din trong nc, ngoi tr b nhim t ngun nc thi ca

ngnh in t, gm s, c quy, sn xut thp.

Niken c c tnh thp v khng tch ly trong cc m. Tiu chun nc ung v

nc sch u quy nh hm lng niken nh hn 0,02mg/l.

19. Thy ngn

Thy ngn him khi tn ti trong nc. Tuy nhin cc mui thy ngn c dng

trong cng ngh khai khong c kh nng lm nhim ngun nc.

Khi nhim c thy ngn cc c quan nh thn v h thn kinh s b ri lon. Tiu

chun nc ung v nc sch u quy nh hm lng thy ngn nh hn 0,001

mg/l.

20. Molybden

Molybden t khi c mt trong nc. Molybden thng c trong nc thi ngnh

in, ha du, thy tinh, gm s v thuc nhum.

Molybden d hp th theo ng tiu ha v tn cng cc c quan nh gan, thn.

Tiu chun nc ung quy nh molybden nh hn 0,07 mg/l.

21. Clorua

Ngun nc c hm lng clorua cao thng do hin tng thm thu t nc

bin hoc do nhim t cc lai nc thi nh m km, khai thc du, sn xut

giy, sn xut nc t quy trnh lm mm.

Clorua khng gy hi cho sc khe. Gii hn ti a ca clorua c la chn theo

hm lng natri trong nc, khi kt hp vi clorua s gy v mn kh ung. Tiu

chun nc sch quy nh Clorua nh hn 300 mg/l. Tiu chun nc ung quy

nh Clorua nh hn 250 mg/l.

22. Amni Nitrit - Nitrat

Cc dng thng gp trong nc ca hp cht nit l amni, nitrit, nitrat, kt qu

ca qu trnh phn hy cc cht hu c hoc do nhim t nc thi. Trong ,

amni l cht gy c nhiu nht cho c v cc loi thy sinh. Nitrit c hnh

thnh t phn ng phn hy nit hu c v amni v vi s tham gia ca vi

khun. Sau nitrit s c oxy ha thnh nitrat. Ngoi ra, nitrat cn c mt trong

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ngun nc l do nc thi t cc ngnh ha cht, t ng rung c s dng phn

ha hc, nc r bi rc, nc ma chy trn. S c mt hp cht nit trong thnh

phn ha hc ca nc cho thy du hiu nhim ngun nc.

Tiu chun nc sch quy nh Amni nh hn 3mg/l. Tiu chun nc ung quy

nh Amni nh hn 1,5 mg/l.Tiu chun nc sch v nc ung u quy nh Nitrit nh hn 3mg/l.

Tiu chun nc sch v nc ung u quy nh Nitrat nh hn 50mg/l.

23. Sunfat

Sunfat thng c mt trong nc l do qu trnh oxy ha cc cht hu c c cha

sunfua hoc do nhim t ngun nc thi ngnh dt nhum, thuc da, luyn

kim, sn xut giy. Nc nhim phn thng cha hm lng sunfat cao.

nng sunfat 200mg/l nc c v cht, hm lng cao hn c th gy bnh

tiu chy.

Tiu chun nc ung quy nh sunfat nh hn 250 mg/l.

24. Florua

Nc mt thng c hm lng flo thp khong 0,2 mg/l. i vi nc ngm, khi

chy qua cc tng vi, dolomit, t st, hm lng flo trong nc c th cao

n 8 9 mg/l.

Kt qu nghin cu cho thy khi hm lng flo t 2 mg/l lm en rng. Nu

s dng thng xuyn ngun nc c hm lng Flo cao hn 4 mg/l c th lm

mc xng. Flo khng c biu hin gy ung th. Tiu chun nc ung quy nh

hm lng flo trong khong 0,7 1,5 mg/l.

25. Xyanua

Xyanua c mt trong ngun nc do nhim t cc loi nc thi ngnh nha, xi

m, luyn kim, ha cht, si tng hp.

Xyanua rt c, thng tn cng cc c quan nh phi, da, ng tiu ha. Tiu

chun nc ung v nc sch u quy nh hm lng xuanua nh hn 0,07

mg/l.

26. Coliform

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Vi khun Coliform (ph bin l Escherichia Coli) thng c trong h tiu ha ca

ngi. S pht hin vi khun Coli cho thy ngun nc c du hiu nhim.

Tiu chun nc ung v nc sch u quy nh hm lng E. Coliform bng 0.

Ring Coliform tng s trong nc sch c cho php 50 vi khun / 100 ml.

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Cac Yeu to Danh Gia Chat Luong Nuoc