Chng 4Phn tch nc4.1 Gii thiu4.1.1 Thy quynMc d nc l mt trong nhng mt hng qu gi nht, nhng n c dng cho nhiu mc ch khc nhau. N c rt nhiu ng dng, l nn tng cho cuc sng v x hi. Nc quan trng ung, con ngi v ng vt khng th tn ti m khng c nc, v s dng cho vic duy tr v sinh c nhn. Nng nghip v cng nghip s dng mt lng ln nc cung cp cho nhiu mt hng tiu dng v thc phm. Mc d, c ci m chng ta n ph thuc hon ton vo nc. Chng ta khng th lm cn kit ngun cung cp nc cho chu trnh thy vn; tuy nhin, chng ta c th lm gim cht lng nc n mt im m ti nc khng th s dng c, thm ch gy hi hoc gy cht ngi. nhim ngun nc nh hng nghim trng n nhiu sng, h v thm ch cc b phn ca i dng.97% nc trn th gii c tm thy trong cc i dng. Ch c 2,5% nc trn th gii l nc ngt khng b nhim mn. Tuy nhin, 75% nc ngt trong cc sng bng v chm bng. Ch c 1% nc ngt c tm thy trong h, sng v t v 24% hin nay l nc ngm. Dn s ngy cng tng nn vic s dng nc cng tng ln, gy p lc cho nhng ngun ti nguyn nc. Trong nm 1975, tng s ton cu s dng nc l di 4000 km3/nm v iu ny d kin s tng ln khong 6.000 km3/nm vo nm 2000. Vic tm kim ngun nc ngt cung cp y p ng nhu cu ngy cng tng ca con ngi v duy tr cht lng tr thnh mt vn . Mc d lng nc c sn khng phi l mt vn trn quy m ton cu, nhng vic tm kim nhng ngun nc c cht lng ti nhng ni c nhu cu dng nc ln l mt vn kh khn.4.1.2 nhim ncKhu dn c v cc ngnh cng nghip t lu c tp trung dc theo sng, ca sng v vng ven bin do u th ca nc trong ngnh thng mi. Vic s dng nc ca khu dn c lm gim cht lng nc bi s xut hin ca cc cht gy nhim khc nhau. Trong lch s, nhim ngun nc khng phi l mt vn ln cho n khi cc trung tm dn s ln pht trin. Sng v bin c kh nng t lm sch, nhng nhim ngun nc s tr thnh mt vn khi n vt qu kh nng t lm sch. Cht gy nhim nc l cht sinh hc, vt l, ha hc hin din qu mc c kh nng gy nguy hi cho cc sinh vt sng, bao gm c con ngi. Cht lng nc xc nh tim nng s dng ca n. V d, cht lng nc cn thit cho cng nghip ph thuc vo cc qu trnh cng nghip. Nc b nhim c th c s dng cho mt s quy trnh nhng khng cho cc qu trnh khc. nhim ngun nc l mi nguy him sc khe nghim trng. Mi ngi c th b bnh t vic ung, git hoc bi li trong nc b nhim. Mi nguy him sinh hc ca nc gm c vi khun gy bnh, vi rt v k sinh trng, trong khi mi nguy him ha hc bao gm nitrat, ch, asen v cc cht phng x. Quan tm ln nht l cht lng nc cung cp cho ngun nc sinh hot nhng phi c loi b cc cht c hi cho sc khe con ngi. T quan im sc khe cng ng iu quan trng nht l ngun cung cp nc sinh hot phi c loi b cc mm bnh vi sinh vt. Tc nhn gy bnh c th c truyn qua nc bao gm nhng vi sinh vt v nhim trng ng rut (bnh l, bnh t, bnh thng hn) v v vim gan truyn nhim v bnh bi lit. cc nc pht trin ca chu u v Bc M, ngun cung cp nc thng loi b nhng sinh vt ny, nhng iu ny khng th lm c cc nc ang pht trin, ni bng pht dch bnh t nc nh st thng hn, t vn cn xy ra. Tuy nhin, ngay c cc nc pht trin, bnh lin quan n nc vn cn l mt mi e da tim nng v ngun cung cp nc thng xuyn c kim tra vi khun coliform, ci m hin din trong phn thi. Ngun cung cp nc cng nn c loi b cc ha cht c hi nh thuc dit cc loi gy hi, thuc tr su, kim loi nng v cc cht phng x.Mt hnh thc ph bin ca nhim nc vt l l nhim nhit. Ngnh cng nghip s dng nc cho mc ch lm mt v nc ny sau c tr li nhit cao hn mi trng xung quanh. Th phm chnh trong lnh vc ny l cc nh my in, cc nh my s dng lng ln ngun nc sinh ra hi nc lm quay cc tuabin to ra in. Nc nng sau c thi tr li sng, h, ca sng v bin. C rt nhy cm vi nhit v tng vi c th tn ph cuc sng ca cc c th trong nc. V l do ny, nhit ca nc phi c gim trong thp lm mt ti nh my in trc khi thi ra ngoi mi trng. Nh cun sch ny cp n cc cht nhim ha hc, l hc v sinh hc, mc d quan trng nhng s khng tho lun chi tit.Bng 4.1 Cht nhim ha hc chnh trong thy quyn nhimNgun tiu biuNhn xt

Cht phng xThi t tai nn ngnh cng nghip ht nhn, vn chuyn vt liu ht nhn v th nghim ht nhn.Ch bc xc. Vn sc khe c tranh lun thng xuyn.

Ha cht hu cS dng cht dit c v thuc tr su nng nghip. Nc thi cng nghip v sinh hot. nhim du trn bin do tai nn ch du. Mt lot cc ho cht c thi (xng du, thuc tr su, cht ty ra). nh hng n sc khe con ngi v h sinh thi thy sinh.

Kim loi nngCht thi t ngnh cng nghip, nng nghip, thot nc th v nc thi t cc h gia nh.Nhiu cht nhim kim loi nh hng n sc khe con ngi v h sinh thi thy sinh (v d nh thy ngn, ch, cadimi)

AxitThot nc t cc m, cht thi t ngnh cng nghip v lng ng axit t bu kh quyn.C th gy tn hi cho cc h sinh thi thy sinh (v d nh axit sulfuric, axit nitric) bng cch tp trung cc kim loi c hi.

Cht dinh dngS dng cc loi phn bn nng nghip v nc thiGy ra hin tng ph dng (v d nh cc hp cht pht pho v nit). Nitrat c th nh hng n sc khe con ngi.

Ngun chnh gy nhim nc: Nc cng, nc thi cng nghip, h thng nc ti cy trng, s c trn du. Cc cht gy nhim v ngun c cp trong bng 4.1. Nhiu cht nhim lin tc thi vo ngun nc mi ngy. Thnh thong vic thi mt s lng ln cc cht thi i hi s quan tm ln ca cng ng. V d in hnh l cc s c gy g r cht phng x t nh my ti ch ht nhn Sellafield Anh vo bin Ailen, th nghim ht nhn ca Php Thi Bnh Dng v tai nn ch du nh Exxon Valdez.4.1.3 Nhu cu oxy sinh ha (BOD)Nc thi i vo sng hoc bin t cng nc thi c th c coi nh l mt ngun nhim im, cng xa ngun thi th nng cht nhim cng gim do s pha long. Cc cht nhim hu c trong nc thi hin nay l vn nhim nghim trng. Vi khun trong nc lm gim nhim hu c, chng s dng oxy ha tan (DO) trong qu trnh ny. Lng oxy cn thit phn hy cht hu c trong mt n v th tch nc c gi l nhu cu oxy sinh ha (BOD). BOD c th l dng c o lng nhim hu c v thng xuyn c xc nh trong cc nh my x l nc v cc phng th nghim cht lng nc. Nu cht hu c hin din qu nhiu v hu qu BOD qu cao, DO trong nc c th qu thp cung cp cho sinh vt thy sinh. S phn hy cht nhim hu c bt u ngay sau khi nc thi vo sng khu vc gn ngun im gi l khu vc nhim, khu vc ny c BOD cao v DO thp. Vng h lu, c mt khu vc hot ng phn hy, ni m DO mc ti thiu do phn hy sinh ha cc cht hu c nhim. Cui cng, c mt khu vc phc hi trong khu vc ny DO tng trong khi BOD gim bi v hu ht cc cht hu c b phn hy. Hu ht cc loi nc c kh nng phn hy cht thi hu c; tuy nhin, vn pht sinh khi nc nhn lng ln cc cht hu c, nhu cu oxy gim. Nu kh nng t lm sch ca nc t nhin qu mnh, tt c oxy ha tan trong nc c th c s dng ht, dn n c cht. BOD c tho lun chi tit trong phn 4.7.4.1.4 Hin tng ph dng haS gia tng nng cc cht dinh dng trong nc c gi l hin tng ph dng ha. Cc cht dinh dng l nhn t cn thit cho s pht trin ca vi sinh vt (C, N, P, K, S v cc kim loi vt). Hin tng ph dng ha l mt qu trnh t nhin v nn c; tuy nhin, hot ng ca con ngi c th lm tng s hin din cc cht dinh dng, dn ti hin tng ph dng ha, l vn chnh trong khu vc rng ln. Nc thi v nc thot ra t t nng nghip giu phn bn, c cha hm lng cao photpho v nito, thi vo ngun nc c th dn n s gia tng s lng thc vt ph du, ci gi l to n hoa. To tr nn qu dy lm nh sng khng th xm nhp vo nc dn n to bn di b mt cht do thiu nh sng. Khi to phn hy oxy ha tan c s dng, c thiu oxy v cng bt u cht.Vn ph dng ha thng gp trong h nhn ngun thi giu cht dinh dng. Gn y, kh nng ph dng ha ca nc thi vng bin ven b vng nhit i c quan tm v tc ng ca n c kh nng gy hi trn cc rn san h. Vn ph dng ha c th c gii quyt bng cch m bo rng nc thi vo ngun nc khng cha qu nhiu cht dinh dng. iu ny c th t c bng cch s dng cc phng php x l nc thi tin tin c kh nng loi b nhng cht ny.Bng 4.2 Tiu chun nh gi hin tng ph dng ha cho h v h cha ncTham sNgho dinh dngDinh dng va phiPh dng

Tng N (g/l)500

Tng P (g/l)20

DO trong nc h (% bo ha)>8010-80 Ksp, dung dch c bo v mui s kt ta.IAP = Ksp, c s cn bng gia dung dch bo ha v mui.IAP < Ksp, dung dch khng c bo ha v mui s ha tan.Trong trng hp trn, IAP (3,19. 10-9) < Ksp (Ksp = 8,7. 10-9) v dung dch khng bo ha. Do canxit s ha tan.Mc ha tan = IAP/Ksp = 3,19. 10-9/8,7. 10-9 = 0,37Qu trnh oxy ha ca ion st (Fe2+) thnh ion st (Fe3+) sn xut thm acid sulfuric:4FeSO4 + 10H2SO4 +H2O 4Fe(OH)3 +4H2SO4H thng thot nc t m c kim sot bng cch nim phong cc m b b hoang, kim sot h thng thot nc v x l ha hc bng vi.t phn cng c th hot ng nh mt ngun axit di iu kin mi trng thch hp. t phn rt giu pyrite (FeS2) v chng c xu hng xy ra m ly v ng bng ven bin. Khi nc mang oxy vo t, st b oxy ha bi sufuric : axit theo phn ng tng t nh trn cho h thng thot nc m axit. pH ca nc c th gim xung di 4 v mc c hi ca nhm c pht tn vo dung dch, t ra mt mi nguy him ng k cho i sng thy sinh. t phn c tm thy ch yu vng nhit i, v d ni ting nht l ng bng Bangkok Thi Lan, ni t phn chim khong 600 000 ha. nh hng ca nhim mi trng c tnh axit bao gm : Ph hy cc sinh vt thy sinh. pH di 4, hu ht cc dng sng cc vng nc b mt cht. Tng n mn. iu ny c th c nh hng n tu thuyn, phn cu trc nm di nc (v d nh cu tu) v h thng ng ng dn nc. Thit hi cho cy trng nng nghip. Nu pH ca git nc ti di 4.5, cc cht c hi i vi cy trng c th b ra tri vo dung dch.4.1.6 mn Trong khi hu ht nc trn th gii l nc mui (tc l nc bin), trong nc ngt khng mong mun c mn. Tuy nhin, nc ngt c th tr thnh nc mn do : Nc thi cng nghip c xu hng cha hm lng cao cc mui v c c hnh thnh bi cc qu trnh cng nghip khc nhau. ng thot nc c cha mui c s dng lm tan chy bng tuyt trn ng cao tc. Ti tiu ha tan mui t t. Nc bin xm nhp vo sng khi triu cao v dng chy thp. Nc mn t cc ging du v m m i khi c pht thi vo nc ngt. mn trong nc ngt c th gy ra mt s vn : Nc mn khng thch hp nh mt ngun nc ung. mn c th nh hng xu n sinh vt sng trong vng nc ngt bi v, khng ging nh cc sinh vt bin, sinh vt sng trong vng nc ngt thng khng thch nghi vi mn cao. mn trong nc ti c th nh hng xu n tng trng thc vt v sn xut cy trng.4.1.7 nhim vng ven bin Cc thnh phn ca nc bin l kh khc so vi cc vng nc ngt, (bng 4.4); nc bin l dung dch in phn tp trung cha s tp trung cao ca vi ion. Hn na, nc bin c kh nng chng thay i pH khi b sung axit hoc kim hn nc ngt do kh nng m ln hn ca n. Mc d l h cha ln nht trong thy quyn, kh nng ca i dng cho hp th cht thi khng phi l v hn v c bng chng v nhim nc bin trn ton th gii. Tuy nhin, cc vng ven bin ang b nh hng ti t nht. Vng nc ven bin nhn c c hai ngun thi trc tip l nc thi vo v sng b nhim chy ra. nhim vng ven bin t lu l mt vn ln trn ton th gii v cc vn ang ngy cng pht trin. nhim ven bin c bit nghim trng cc nc ang pht trin, ni m nc thi v cht thi c thi vo ca sng v vng nc ven bin khng qua x l trc. Thng thng, cc dng thi cha y cht thi hu c cao trong hm lng dinh dng. Mt dn s cc vng ven bin, ngay c trong cc khu vc m cho n gn y c th c coi l xa hoc nguyn s, tng ln do s m rng ca du lch nh mt ngun thu ngoi t ln nhiu quc gia ang pht trin. nh hng ca nhim mi trng ven bin trn sc khe cng ng l mt mi quan tm nghim trng nh thy sn l ngun chnh v a thch ca dinh dng trong cc quc gia. Tng nhim vng nc ven bin e da cho c du lch v sn xut hi sn. nhim ven bin mang theo n nhng mi e da : S thiu oxy trong nc. Nc x thi vi nng cc cht dinh dng cao c th sn xut to n hoa v dn n kh oxy ca vng nc ven bin. Phn hy ca cht hu c s dng oxy v suy gim DO qu mc c th dn n ci cht ca c v cc sinh vt khc trong c trang tri nui c ven bin v nh bt thy sn, lm gim nng sut bin tng th v gim ngun cung cp thc phm. Tch ly sinh hc cc kim loi c hi. Kim loi c hi trong nc thi c th c tch ly trong hi sn, c bit l ng vt c v nh s, trai v s huyt, n mc vt qu tiu chun sc khe cng ng, mt mi nguy him sc khe cho nhng ngi n hi sn. nhim vi sinh vt. Vic x nc thi th lm cho nc bin ven b mang theo n s e da ca nhim vi sinh vt ca nc v thy sn. Tng mc ca vi khun E. coli trong vng nc ven bin c lin quan ti cc triu chng ca ng tiu ha v bnh ngoi da ca ngi tm bin. Tiu th thy sn b nhim bn cng l mt vn y t quan trng cc nc ang pht trin. Tuy nhin, s bng pht ca ng c thc phm bi hi sn, c bit l ng vt c v, khng phi l him ngay c cc nc pht trin, bng chng l cnh bo cng khai a ra theo thi gian. Thy triu . Tim nng tch ly ca nhim ven bin l s n hoa ca to c, ci gi l thy triu , l mt iu quan trng trong khu vc ven bin ca nhiu nc ang pht trin. Thy triu l do s hin din ca mt loi to c th, mt loi c bit quan trng ng l Pyrodinium bahamense var.compressa. Thy triu phi chu trch nhim cho ci cht ca nhiu sinh vt hn hai thp k qua, ch yu l trong s c nhng ngi n ng vt c v t vng h tr n hoa ca to c. Mt li gii thch c th c xut cho s xut hin ngy cng tng ca thy triu l s thay i t l nit pht pho trong nc thi v ti lng dinh dng ngy cng tng c th gp phn vo mt s thay i trong a phng thng tr loi thc vt ph du, vi trng to c hi di di to ct.

4.1.8 nhim nc ngm Nc ngm t lu c s dng cho nc ung v n vn rt quan trng n ngy nay. M, c khong 50% dn s da vo ngun nc ngm nh l ngun nc ung. Bi v nc ngm nm cch li vi mt t, nn hu ht mi ngi u cng nhn rng nc ngm tng i tinh khit v khng nhim. Mc d hu ht nc ngm c cht lng cao, ti mt s a im n ang tr nn kh khn duy tr tinh khit ca nc ngm. S nhim ngun nc ngm bao gm : S xm nhp mn. Qu trnh khai thc nc ngm qu mc l nguyn nhn gy nn h thp mc nc ngm, lm cho nc bin xm nhp v gy nhim tng ly nc. Bi chn lp: R r ha cht t cc bi rc thnh ph v cng nghip c th xm nhp qua t v lm nhim nc ngm. Phng php kim kim sot s nhim ny bao gm vic s dng ming lt ngn chn s r r v h thng thu thp nc thi r ra t bi chn lp. Nhng b cha ngm. Bc M c th c ti 1.4 t b cha du ngm v hp cht nguy hi khc. S r r ch mt vi lt ca nhng hp cht ny c th gy nh hng n cht lng nc ngm. Nng nghip. Mt vi hot ng nng nghip ng gp vo s nhim nc ngm: s dng phn bn v thuc tr su, thy li v hot ng chn nui gia sc. Nc thi nng nghip c th r ra t v gy nhim bn ngun nc ngm. B t hoi. B t hoi thng c s dng nng thn v khng kt ni vi cng thot. Thm ch mt t nc pht trin nh l M vn c hn 20 triu b t hoi. R r t b t hoi thit k t v hot ng km c th gy nhim ngun nc ngm vi cc cht dinh dng, cht c v vi khun. Ging du. Cc ging du b b hoang c th gy nhim ngun nc ngm vi nc bin khi v bc ca n b v. H thng thot nc ng. Mui c dng lm tan tuyt, cc cht ha hc t nhng tai nn trn du v cc cht khc thot ra h thng thot nc ng c th r r qua tng cha nc. Vn cn mt s ngun khc bao gm cc bi thi cht phng x, khai thc m v bi xy dng. Nc ngm khc so vi nc b mt. S phn hy cc cht nhim ca vi khun v cng chm do khng c mt ca vi khun hiu kh trong nc ngm bi v thiu oxy. Nh vy, t l dng chy ca nc ngm thm qua l rt chm so vi tc chy ca nc b mt v s nhim khng th pha long v phn tn mt cch d dng c. Tuy nhin, v t c th lc mt s cht nhim.

4.1.9 X l nc thi Cng tc phng chng bnh lin quan n nc l nguyn nhn chnh ca vic gii thiu cc phng php kim sot nhim. Trong thi trung c Chu u, nc thi c thi ra ng ph v ng li . Anh, nc c thi ra sng bt u vo khong nm 1810. Trong sut thi k cuc cch mng cng nghip, nhiu dng sng rt nhim v dch t, dch bnh rt ph bin. H thng thot nc u tin c t Hamburg, c, nm 1843 v h thng thot nc u tin M c xy dng nm 1855. B lc nc u tin c gii thiu u tin ti Anh vo u th k 19 nhng n khng loi b c tc nhn gy bnh. Vo nm 1875 lut y t cng ng u tin c thng qua ti Vng Quc Anh, lm cho chnh quyn a phng c trch nhim hn trong vic x l nc thi. Lut ny ni rng nc thi khng c cha cc vi khun gy bnh, nhng cng ngh cn lm iu ny cha c. Lut ngn chn nhim cc dng sng c thng qua Vng Quc Anh vo nm 1876, cm x trc tip nc thi cng nghip ra cc con sng. Cc ngnh cng nghip c yu cu x nc thi vo h thng cng v hi ng th trn chu trch nhim cho vic x l nc thi. M, h thng x l nc thi c xy dng u tin vo nm 1870 v vo nm 1910 c khong 10% nc thi ti M c x l. Cng ngh kh trng c gii thiu u tin vo u th k 20 ti Anh v ngy cng c s dng rng ri nhiu nc gim tc nhn gy bnh trong nc. Hin nay, nhiu quc gia pht trin, gn 100% nc thi c x l v nhiu quc gia ban hnh lut v tiu chun cht lng nc (xem ph lc III). Tuy nhin, nhiu nc ang pht trin, x l nc thi l hu nh khng c v nc thi c x trc tip ra cc ngun nc gy ra cc vn nhim nghim trng. H thng x l nc thi c thit k t nhng v tr c bit sao cho n c th tip nhn nc thi t nhng h gia nh v nh my cng nghip. Mt s nh my c h thng x l nc thi ring c thit k gim cht nhim ti ch. Sau x l, nc thi c thi ra ngun tip nhn (sng, h hay bin). X l nc thi c phn loi nh sau: x l s b, x l bc hai v x l bc cao, theo th t tng dn kh nng thanh lc. X l s b. y l x l th s nht loi b hu ht cc cht rn trong nc v gim hm lng BOD. Nc thi s c a qua song chn rc loi b ht cc vt rn ni ln. Tip theo, nc thi s i qua b lng ct y ct, v si s lng nh trng lc xung y ca b. Cn lng s c chn lp. Sau nc thi s chuyn qua b lng cp hai ni m cc cht rn l lng c lng hnh thnh bn v s c thu thp v x l. Cc cht ha hc c thm vo gip qu trnh lng xy ra. X l s b loi b khong 60% cht rn v xp x khong 35% BOD. N l loi x l ph bin nht v nhiu nh my s dng x l. X l bc hai. X l ny s dng qu trnh sinh hc loi b cc vt liu l lng v lm gim BOD. X l bc hai thng dng qu trnh bn hot tnh, mt d lc nh git cng c s dng. Nc thi c a vo b sinh hc hiu kh, n c trn vi khng kh v bn hot tnh c tun hon cc b lng pha sau. Nc thi c lu trong b vi gi v vi khun hiu kh c mt trong bn s phn hy cc cht hu c trong nc thi. Nc thi sau s chuyn qua b lng tch bn ra khi nc thi. Mt t bn s c tun hon tr li b hiu kh. Hu ht bn c a n b phn phn hy bn ni m bn c x l bng vi khun k kh, gim lng bn. Mtan c to ra trong qu trnh phn hy c t chy hoc s dng lm nhin liu trong cc nh my. Bn sau c lm kh v chn cc bi chn lp. Trong lc nh git, nc thi c phun u trn b mt ca b lc vi lp vt liu c khe rng (, mnh gch v, vv). Cc vi sinh vt hnh thnh nn lp mng trn vt liu v tiu th cht dinh dng t nc thi,v nc c thu y b. Xp x 90% cht rn v BOD c th c gim bi x l bc hai. X l bc ba hay x l bc cao. X l bc ba c thit k lm gim nng ca cc cht nhim c bit trong nc thi. Nhiu qu trnh x l c s dng da vo cht nhim cn loi b. X l bc ba c th loi b cht rn l lng, hp cht hu c ha tan, cht dinh dng ho tan (photpho v nito) v nhiu kim loi nng. Phng php ny bao gm lc ct, lc carbon, in thm tch, RO, trao i ion v s dng ha cht thm vo nh keo t to bng v oxi ha (ozone, H2O2). Mt vi qu trnh c th tng i t tin. X l bc cao c th loi b hn 95% cht nhim trong nc thi, nhng n khng c s dng rng ri trong h thng x l nc thi. Bt k loi x l no c s dng, nc thi c x l cui cng vi kh clo trc khi thi ra mi trng. Lm nh vy vi khun gy bnh s c tiu dit. Nh hiu qu ca qu trnh x l s b v x l bc hai m n c s dng rng ri trong h thng x l v c tm tt trong bng 4.3. Nc thi vo v ra khi h thng x l nc thi c phn tch mt s thng s c tho lun trong chng ny. Nhiu qu trnh x l phi c thit k c bit cho loi nc thi yu cu x l v v th rt cn thit cho vic phi bit loi v nng cht nhim trong dng thi c th x l. Thm na n rt cn thit xc nh rng nc thi c x l t tiu chun v mt php l ban hnh v c th c thi ra mt cch an ton vo mi trng. Nhiu qu trnh yu cu kim sot cn thn trong iu kin vn hnh (vd pH) v n c th cn thc hin phn tch vi cng on trong sut qu trnh x l. Mt nh my x l nc thi hin i c th ci t lin tc, theo dng, ci t dng c phn tch.

Bng 1.3 Hiu qu ca loi b cht nhim trong dng thi bi qu trnh x l nc thi thng thng trong cc nh my:Hiu qu loi b (%)

Thng s/cht nhimCh x l s bX l s b v x l bc hai

Cht rn l lngTng NTng PKhong ha tanBODCOD6020100353090503059080

4.1.10 X l nc cp Trung bnh, mi ngi dn M s dng 300 n 400 lt nc mi ngy cho mc ch sinh hot (ung, tm git, nu n,v sinh, nc ti vn). Xp x 8% ngun nc ngt trn th gii c s dng cho mc ch sinh hot. Nc s dng cho sinh hot c ly t ngun nc ngm v ngun nc b mt. Nc ngm, c ly ra t tng cha nc di tng nc, l ngun nc quan trng cho nc sinh hot. Ging vn c s dng bm nc ngm nhiu vng nng thn. Mc d thng thng nc ngm c cht lng cao hn nc b mt nhng n cng d b nhim (phn 4.1.8 cp). Nc s dng cho sinh hot phi c x l t tiu chun quc gia v nc ung (tham kho ph lc III). Xp x 60% nc c s dng cho mc ch sinh hot c thi ra sng nh nc thi. nhng t nc ng dn v hot ng cng nghip pht trin, thi ng gp vo tng dng chy ca sng cao, c bit trong thi k kh hn. Do , nc thi c x ra sng c th ha vo h lu v cung cp nh mt ngun nc sinh hot cho cng ng khc. Ni cch khc, nc thi ca ngi ny l nc ung ca ngi khc v l iu quan trng phi duy tr cht lng nc mc cao bo v sc khe cng ng. Ni chung nc c s dng cho sinh hot u tin c lu tr trong mt h cha, cn s lng v c loi b, ci thin cht lng nc. Nc sau s c x l trong nh my x l nc trc khi cung cp nc cho thnh ph. X l khc nhau da vo cht lng ca ngun nc, nhng ni chung bao gm lc v x l ha hc (vd Oxi ho bng clo, flo). mt vi ni, ni m c t ngun nc ngt, nc bin c kh mui. Phn tch nc c tin hnh hng ngy trong nh my x l nc m bo t tiu chun. Do vn lin quan n cng ng (c coi l khng c c s) v cht lng nc sinh hot, v v v ca nc kh trng bng clo, nhiu ngi thch ung nc khong ng chai hn. Phn tch nc c thc hin hng ngy ti nh my sn xut nc ng chai, v nh sn xut c yu cu cung cp c th thnh phn trong nc. Mc d c nc ung ng chai v nc sinh hot cc nc pht trin ni chung l an ton ung, n s b loi b trong trng hp nhim bn, khng c kim sot cht lng trong phng th nghim. iu khng c g ngc nhin khi c xp x 1000 cht c th hin din trong ngun nc c cung cp cho cng ng, v cc phng th nghim. Nc c th b nhim bn trong sut qu trnh phn phi. V d, xem st s c mt ca ch trong nc ung. Ngun gc ca ch chnh l gia ng dn nc chnh v nh, ng dn trong cc ta nh, hn ch trong ng ng v cc van nc bng ng. Ngy nay, nhim ch trong nc ung l vn chnh trong cc ta nh c. Nc c th v tnh b nhim trong sut qu trnh x l nh l kt qu ca s l l, v nh l s c trong cc bo co cho nc khong ng chai v nc sinh hot. 4.1.11 Phn tch ncPhn tch nc c th lin quan n bt k loi nc no sau y: Nc mt t h, sng, bin, nc ngm, nc ung, nc thi cng nghip, thnh ph v nc ca l hi. Nng cc ion chnh trong nc b mt c lit k trong bng 4.4. Cht lng nc theo di mt cch thng xuyn trong cc nh my x l nc thi v x l nc.Cc phng php c pht trin cho mt lot cc cht phn tch v c v hu c s dng mt lot cc k thut phn tch. Cc phng php c thng qua bi cc ngnh cng nghip nc ny c gi l phng php chun. Cc phng php m c th d dng thc hin bng cch s dng thit b c bn c a ra trong cun sch ny, v mt s trong s ny c chuyn th t cc phng php tiu chun.C nhiu thit b phn tch nc t ng c bn trn th trng. Trong lnh vc phn tch nc th phng php so mu v in ha c s dng ch yu. Hu ht cc phng php th nghim lin quan n vic b sung cc cht phn ng dng vin hoc dng bt, sau ny c cung cp trong gi.Bng 4.4 Nng cc ion chnh trong nc bin, h ngp mn v nc sngTHNH PHNNC BINH NGP MNNC SNG

HCO3-

140180-17 400

17.9-183

SO42-2649

264-13590

0.44-289

Cl-18980

1960-112900

2.6-113

NO3-2

1.2-1.6

0.3-1.9

Ca 2+400

3.9-15800

5.4-94

Mg2+1272

23-41 960

0.5-30

Na+105561630-67500

1.6-124

K+380112-75600.0-11.8

Cc cht phn ng thng s dng tng t nh trong phng php chun nhng c ly vi lng cn trc. Cc quy trnh c pht trin cho nhng b dng c kim tra c thun tin v d lm. Mt v d l b kim tra Hach (xem ti liu tham kho trong danh sch di y). Mt s b dng c cng bao gm cc u d di ng cho pH, nhit , dn in v oxy ha tan. u d cm tay da trn chn lc ion in cc ngy cng tr nn ph bin phn tch cc thnh phn ha hc khc nhau. Cc phng php s c tho lun y rt thch hp cho bt k loi mu nc no, nhng gi s rng hu ht cc mu l mu nc mt c ly t sng, h, nc ven bin hoc nc thi. Bn cng c th p dng cc phng php phn tch ny phn tch nc ngm v nc khong ng chai.4.1.12 Ly mu v bo qun muTh tch mu c thu thp s ph thuc vo s lng cc phn tch s c thc hin. Nu mt phn tch ton din nc c thc hin, th phi thu thp 2L mu. Nu phn tch ch xc nh mt hoc mt vi thng s th th tch mu cn ly nh hn v ty thuc vo khi lng cn thit cho phn tch . C th dng chai nha hoc thy tinh ty thuc vo cht phn tch. Trong mt s trng hp vic thu thp cc mu chai khc nhau l cn thit. Phn tch oxy ha tan i hi chai ring bit.Bn nn nh rng cc mu m bn thu thp ch i din cho a im v thi im m bn ly mu. kho st chi tit v nc th cn iu tra nhiu v tr v thi im khc nhau. Cc thnh phn ca mu cng c th thay i trong qu trnh vn chuyn v lu tr, ch yu l do phn ng sinh ha v phn ng b mt. Hy chc chn bn thc hin theo cc quy trnh c ngh cho mi phn tch.Mu nc b mt th d ly nht. Vic ly mu nc su th yu cu nhng k thut ly mu c bit, trong c mt s loi (Ruttner, Kemmerer, Dussart, Valas, Watt, vv). Vic ly mu ph bin nht l ly mu Van Dorn, th hin trong hnh 4.1. Dng c ly mu bao gm mt hnh tr rng bng nha PVC v hai van cao su t hai u. Hai van c ni vi nhau bng mt ng cao su v cng c mt chui gn lin vi chng. Trc khi ngm trong nc hai van c ko ra v cc dy c gn vo bn ngoi xi lanh. Xi lanh, m hai u, c h xung n su mong mun bng dy c chia di. Mt vt ly mu bng kim loai c di chuyn theo dy. Cc vt ly mu ny lm dy cao su cng ra v ng xilanh li. Cc mu sau c ko ln khi mt nc v mu chuyn vo mt chai lu tr. N cng c th ly mu t su khc nhau bng cch bm nc qua mt ng nha h xung n su mong mun. Bn thng s thu thp mu ti mt nc hoc nhng v tr gn mt nc. Hy ly chai ly mu sch, cha y nc tinh khit trong phng th nghim n a im. nc trong chai ra v sau ra sch nhiu ln vi nc s c ly. Mi ln ly cch xa v h lu. Cui cng in vo cc chai mu, nim phong, dn nhn v mang n n phng th nghim phn tch. Chai cn c y t t trnh nhiu lon khng kh v bt kh. Khi ly mu nc ging v vi nc, my bm hay vi nc nn cho nc chy tun ra ng y cung cp cho mt mu i din. Vt liu lm chai, cht bo qun v thi gian lu tr c a ra trong bng 1.4. Thi gian lu tr trch dn t bng cn c xem xt nh ln cho php ti a. Mu c ly tin hnh phn tch cng sm cng tt, nhng thc t iu ny c th khng thc hin c. Khi , i vi tng phn tch chng ta s tin hnh cc quy trnh bo qun, lu tr v x l mu c th. V d, vic phn tch DO th yu cu cn thm cht bo qun mu ti hin trng. Vic phn tch cc cht dinh dng ( nito, photpho) cn c thc hin cng sm cng tt, nu tr hon th trong mu s din ra cc qu trnh trao i cht dn n kt qu phn tch khng cn i din cho mu. Mt s quy trnh bo qun c khuyn co cho cc mu cht dinh dng khi chng khng th c phn tch kp thi: Lm lnh: H nhit xung nhng khng loi tr cc phn ng sinh ha; t l phn ng 40C ch bng 250C. Lm ng: Lm gim cc phn ng sinh ha hn na. Thm acid: H thp pH, lm gim hot ng ca vi sinh vt. Thm cht dit khun: Nhiu chng ca vi khun c s dng loi b hon ton cc hot ng ca vi sinh vt; chloroform v thy ngn (II) clorua l ph bin nht.4.1.13 LcLc thng c s dng trong phn tch nc tch cc thnh phn ha tan t nhng cht l lng c hin din trong nc. Tuy nhin, lc c th tn ti mt s vn : S xm nhp ca cc cht khng ha tan qua b lc: Qu trnh c bn ca lc l mu di chuyn qua lp vt liu lc c kch thc khe rng khong 0.45 pm, v cc phn t di chuyn qua b lc c gi l cht ha tan. Trong thc t th nh ngha ny mang tnh c on v khng chnh xc khi keo v polime c th di chuyn qua b lc cng vi cc cht tht s ha tan. S nhim bn: Cht c trong vt liu lc c th ha tan vo mu trong qu trnh lc. iu ny l mt mt vn c bit khi phn tch kim loi vt trong cc mu tng i sch. B lc phn tch kim loi vt phi c ra bng axit trc khi s dng, loi b bt k cht gy nhim kim loi no t cc vt liu lc. Hp ph: Mt s cht phn tch c th hp th vo vt liu lc hoc n v lc. V d, mt s kim loi c th c hp ph trn thnh ca cc n v lc thy tinh. Hng dn lc c a ra trong cc th nghim thch hp. Cc b lc nn c lm lnh trc bng cch ra, u tin bng nc trong phng th nghim v sau vi mt s mu cn c lc. Ch sau khi mu thch hp c lc. Cc n v b lc lm bng thy tinh v nha c sn.Tt c tay cm thy tinh v bnh chn khng th hu nh thch hp cho vic phn tch vt khi quan st thy khng c s hp ph. Tuy nhin, cc thit b khc c th ph hp cho cc phn tch chung (v d nh phu Buchner v bnh lc). Mt n v lc in hnh c th hin trong hnh 4.2. Chn khng c to ra bng cch ni bnh vi mt my bm khng kh hoc mt ci ng ht nc v bt my bm trc khi ni vo bnh. Khi lc xong, cc ng ni phi c ngt ni t ng ht nc hoc bm trc khi bm hoc ng nc tt.Vi phn tch kim loi, mu phi c axit ha sau khi lc.A xit ha trc khi lc c th ha tan mt s kim loi, v do cc kt qu phn tch s khng cn chnh xc. Qu trnh lc l cn thit khi lu tr mu trong thi gian di v n loi b mt lng ln yu t sinh hc, nhng vt liu sinh hc ny c th gy phn ng vi cc cht cn phn tch trong qu trnh lu tr mu.4.1.14 Nhng vn v cu hi1. Mc d nc l mt trong nhng ngun ti nguyn di do nht, s c sn v cht lng ca n trong tng lai li ang tr thnh mi quan tm? Tho lun.2. Din t v cc mc ch s dng nc, v gii thch s nh hng cht lng nc n vic s dng ny.3. Ch ra nhng cht gy nhim nc khc nhau v ngun gc ca chng.4. Din t qu trnh ph dng ha.5. Gii thch ch s DO v BOD thay i nh th no khi cch xa ngun thi?6. Din t cc cch x l nc nhim ( s cp, th cp, trung cp)7. thu c mu i din chng ta cn quan tm ti nhng vn g?8. Tnh ton thi gian lu trung bnh ca Na+, Cl-, Ca2+, trong bin, khi ly th tch ca bin l 1,23. 1021lt. Dng chy ca sng bin l 3,6.1016 lt.a-1, nng trung bnh trong nc sng ca Na+, Cl-, Ca2+ l 6,3; 7,8; 15 m/l. Gi tr trung bnh ca cc cht to nn s hp thnh nc bin c ghi bng 4.4 v t trng ca nc bin l 1.025 kg/l. Khng quan tm n nhng u vo ca nc bin nh nc ma,v chng trng thi n nh.9. Tnh ton lc ion trong mu nc sng vi cc thnh phn nh sau (mg/l): 108 HCO3-, 19 SO42-, 0,5 F-, 4,9 Cl-, 0,3 NO3-, 23 Ca2+, 6,2 Mg2+, 16 Na+, v 0,1 K+ ( xem v d 5.1)Tr li cu hi:Cu 1: Mc d nc l mt trong nhng ngun ti nguyn di do nht, s c sn v cht lng ca n trong tng lai li ang tr thnh mi quan tm:97% nc trn th gii c tm thy trong cc i dng. Ch c 2,5% nc trn th gii l nc ngt khng b nhim mn. Tuy nhin, 75% nc ngt trong cc sng bng v chm bng. Ch c 1% nc ngt c tm thy trong h, sng v t v 24% hin nay l nc ngm. Dn s ngy cng tng nn vic s dng nc cng tng ln, gy p lc cho nhng ngun ti nguyn nc. Trong nm 1975, tng s ton cu s dng nc l di 4000 km3/nm v iu ny d kin s tng ln khong 6.000 km3/nm vo nm 2000. Vic tm kim ngun nc ngt cung cp y p ng nhu cu ngy cng tng ca con ngi v duy tr cht lng tr thnh mt vn . Mc d lng nc c sn khng phi l mt vn trn quy m ton cu, nhng vic tm kim nhng ngun nc c cht lng ti nhng ni c nhu cu dng nc ln l mt vn kh khn.Cht lng nc trong tng lai ngy cng gim st. Nguyn nhn l do cc khu cng nghip thi mt lng ln nc thi vo ngun nc, dn s ngy cng tng dn n lng nc cng c s dng nhiu hn v lng nc thi thi ra cng nhiu hn. Nhiu cht nhim lin tc thi vo ngun nc mi ngy. Nhng s c trn du trn bin gy nhim ngun nc, v cc s c lm r r cc cht phng x ra ngoi mi trngCu 2: Nhng cng dng ca nc v s nh hng ca cht lng nc n vic s dng ny:Nc l nn tng cho cuc sng v x hi. Nc quan trng ung, con ngi v ng vt khng th tn ti m khng c nc, v s dng cho vic duy tr v sinh c nhn. Nng nghip v cng nghip s dng mt lng ln nc cung cp cho nhiu mt hng tiu dng v thc phm.Khi ngun nc b nhim th s lm nh hng n cng dng ca n. Khi nc b nhim th chc nng ung ca n khng cn na v nu ung th s nh hng nghim trng n sc khe ca con ngi. Nc b nhim s khng cn c dng duy tr vic v sinh c nhn. Hn th na, mt khi nhim th nc khng cn th hin c vai tr vn c ca mnh trong cc hot ng cng nghip v nng nghip, ngi ta khng th dng nc nhim nng ti cho cy trng, v cng khng th dng nc nhim phc v cho cc ngnh cng nghip ch bin thc phm. Tm li, khi nc nhim th thay v th hin cng dng hu ch th chng li th hin tc hi ca mnh trong mi lnh vc ca i sng x hi.Cu 3: Cc cht nhim v ngun gc ca chng: Cht nhim trong nc gm cht ha hc, vt l v sinh hcCht nhim ha hc nhimNgun tiu biu

Cht phng xThi t tai nn ngnh cng nghip ht nhn, vn chuyn vt liu ht nhn v th nghim ht nhn.

Ha cht hu cS dng cht dit c v thuc tr su nng nghip. Nc thi cng nghip v sinh hot. nhim du trn bin do tai nn ch du.

Kim loi nngCht thi t ngnh cng nghip, nng nghip, thot nc th v nc thi t cc h gia nh.

AxitThot nc t cc m, cht thi t ngnh cng nghip v lng ng axit t bu kh quyn.

Cht dinh dngS dng cc loi phn bn nng nghip v nc thi

Cht nhim vt l l nhit , th phm chnh l cc nh my in, cc nh my s dng lng ln ngun nc sinh ra hi nc lm quay cc tuabin to ra in. Nc nng sau c thi tr li sng, h, ca sng v bin.Cht nhim sinh hc gm c vi khun gy bnh, vi rt v k sinh trng.Cu 4: Qu trnh ca hin tng ph dng ha:Nc thi v nc thot ra t t nng nghip giu phn bn, c cha hm lng cao photpho v nito, thi vo ngun nc c th dn n s gia tng s lng thc vt ph du, ci gi l to n hoa. To tr nn qu dy lm nh sng khng th xm nhp vo nc dn n to bn di b mt cht do thiu nh sng. Khi to phn hy oxy ha tan c s dng, c thiu oxy v cng bt u cht.Cu 5: S thay i ca BOD v DO l:S phn hy cht nhim hu c bt u ngay sau khi nc thi vo sng khu vc gn ngun im gi l khu vc nhim, khu vc ny c BOD cao v DO thp. Vng h lu, c mt khu vc hot ng phn hy, ni m DO mc ti thiu do phn hy sinh ha cc cht hu c nhim. Cui cng, c mt khu vc phc hi trong khu vc ny DO tng trong khi BOD gim bi v hu ht cc cht hu c b phn hy.Cu 6: Cc qu trnh x l ncX l bc 1 (s b)X l bc haiX l bc ba (bc cao)

loi b hu ht cc cht rn trong nc nh song chn rc, lng trng lc trong cc b lng. Gim hm lng BOD Loi b khong 60% cht rn v lm gim c 35% BOD. N l loi x l ph bin nht v nhiu nh my s dng x l.

X l ny s dng qu trnh sinh hc loi b cc vt liu l lng v lm gim BOD. X l bc hai thng dng qu trnh bn hot tnh, lc nh git t c s dng. Xp x 90% cht rn v BOD c th c gim bi x l bc hai.

X l bc ba c thit k lm gim nng ca cc cht nhim c bit trong nc thi. Lc ct, lc carbon, in thm tch, RO, trao i ion v s dng ha cht thm vo nh keo t to bng v oxi ha (ozone,H2O2) X l bc cao c th loi b hn 95% cht nhim trong nc thi Khng c s dng rng ri.

Cu 7: c c mu i din chng ta cn phi: Chun b trc khi ly muTh tch mu: Nu phn tch mu nc ton din th ta ly 2L mu, cn nu ch phn tch mt vi thng s th ta ly th tch mu nh hn ty thuc vo khi lng mu cn thit cho phn tch. Dng c ly mu: dng chai nha hoc thy tinh ty thuc vo bn cht ca cht cn phn tch. Khi phn tch mt s thng s c bit chng hn nh DO th cn dng chai rin cha mu. Ly mu: tin hnh ly mu theo ng trnh t hng dn. i vi nhng thng s cn phn tch ti hin trng th ta s tin hnh phn tch ti hin trng cn i vi nhng mu phi em v phng th nghim phn tch th chng ta tin hnh bo qun mu cn thn v thm vo cc cht c nh mu ph hp vi tng mu c th.Sau khi ly mu ta tin hnh ghi tn v dn vo chai cha mu sau em v phng th nghim tin hnh phn tchCu 8:Cu 9: 108 HCO3-, 19 SO42-, 0,5 F-, 4,9 Cl-, 0,3 NO3-, 23 Ca2+, 6,2 Mg2+, 16 Na+, v 0,1 K+Lc ion ca mu nc: = CiZ2i = . (. (-1)2 + . (-2)2+ . (-1)2+ . (-1)2+ . (-1)2+ . 22+ . 22 + .12+ . 12). 10-3 = 7,796. 10-34.1.15 Gi cho vn 1. Quan tm nhng thng tin trong nc thi, v x l chng trong khu vc ca bn (huyn/thnh ph) bao gm:* S to thnh ca nc thi* Th tch nc thi thi ra ngoi* Cng ngh x l nc thi* Tiu chun dng ra ca quc gia hoc i phng.Phn loi v xc nh s lng, phn loi nc thi da vo ngun gc nh: sinh hoat, cng nghip, nng nghip. Bn c th thu thp c cc thng tin hu dng t vic s dng nc cng a phng, v cng c kim sot nhim ca ban qun l ca a phng (hi ng, qun l huyn)Nu s lng thng tin cn tm c sn bn c th tnh ton phn trm ca tng cht nhim (nng x th tch tng cht).Bn c th sp xp n tn hin trng cng nc x thi v bn s c cc cch x l nc thi khc nhau, a ra nhng kin xem xt nhng cng ngh x l nc thi, tiu chun v chin lc qun l ngi lao ng x hi.Thu thp s liu m bn c c bng vic quan st bng mt rt k lng v biu din chng ra 1 dng no (bng, th, biu trn, biu ng) v chun b thuyt trnh v nhng g bn tm kim c. Hin ti bn c th trnh by nghin cu ca mnh trong cuc tho lun, v tho lun thm na vi cc bn ca mnh.2. em kin thc ca bn thn vo quan trc cht lng nc mt ti khu vc ca bn bng cch thu thp 1 s mu nhng v tr khc nhau, v phn tch chng theo cc trnh t chun c sn cc chng trn. Bn xem xt phn tch mi mu 2 hoc 3 ln v trnh by li cch o chng.bn s c nhiu tng trong qu trnh phn tch ca bn. Tip tc th hin kt qu ca bn ra 1 bng, bn c th thay i mu sc nhn th v hn, thch hp ch theo di.3. a vo chi tit cch phn tch dng ra ca cng nc thi c din t bng cc phng php chng tip theo v tip tc a kt qu ra 1 bng s liu.4. Phn tch mu nc my t 1 s gia nh ca khu vc bn, ngoi ra phn tch nhng chai nc khong v c khc nhau cc siu th. Sau i chiu cht lng nc my v nc ng chai.4.1.16 Ti liu tham kho:CF C Mason, cc kha canh sinh hc ca nhim nc ngt trong quyn sch : nhim, nguyn nhn, nh hng, kim sot xut bn ln th 2 ca RM Harrison, ng hong ca ngnh ha, cambridge, 4.1.17 c thm ti liu: practical environmental analysis trang 1574.2 Cht rn trong nc:4.2.1 Gii thiu:Gii hn cht rn c cp n s lng cht rn cn li trong mu nc sau khi sy, gia nhit 1 nht xc nh. Phn loi cht rn c nh ngha nh: tng s, ha tan, huyn ph, lng, c nh v d bay hi. Tr s gia cht rn ha tan v cht rn l lng trong nc c thc hin bi qu trnh lc. Cht rn trong nc khng c mong mun v nhiu l do, cht rn lm gim cht lng nc ung v gim cht lng nc ti tiu cy trng v cng nghip. Nc vi hm lng cht rn cao, x l bng cc bin php vt l, ha hc, cng vi vic lm sch nn gi thnh x l nc t. Hn na hm lng cht rn trong nc cao lm tng t trng ca nc, nh hng n s thm thu ca sinh vt trong nc v lm gim cc kh ha tan. Cht rn l lng cha c x l trong nc thi c th dn n vic tch ly bn v to iu kin k kh xy ra nc mt.Cc ngun chnh ca cht rn trong nc t nhin l nc, ma v gi xi mn b mt t. Xm thc ca nc th hin r rt hn trong khu vc m t v bn m t, vi nhng cn bo ln hoc ma ko di, (v d khu vc kh hu gi ma). Xm thc ca gi rt ph bin vng kh hn, (tho nguyn nc M, ng c ln nhit i. Cht rn c ngun gc t t, gim trong ca nc, hn ch qu trnh quang hp v dn n tng b dy ca lp trm tch y, gim su ca mc nc trong h, ao, sng. V sau, c th lm tng tn s, mc nghim trng ca l lt.Nc thi ca thnh ph v khu cng nghip, b nhim bi cht rn c ngun gc t cht thi sinh hot h gia nh, nc chy mt ng v ca qu trnh cng nghip. Khng ging nh nhng ngun phn tn cht rn trong t nhin nh cp trn, nhng cht rn ny c th c pht ra t nc thi trong cc nh my x l nc thi. S lng cht rn l lng tng theo qu trnh nhim nc. Trong bn, phn ln cht rn dng huyn ph v mt phn nh ca cht rn ha tan. Nng cc loi cht rn trong nc thi dn c cha x l c cho trong bng 4.5. Tng cht rn ha tan trong nc ung dao ng t 20 n 1000 mg/l, bao gm ch yu mui v c, mt s hp cht hu c v kh ha tan.Bng 4.5 Thnh phn cht rn trong nc thi dn c vi nhng mc cht nhim khc nhauThnh phn cht rn (mg/L)Mc nhim

tTrung bnhNng

Tng cht rn (TS)3007001000

Tng rn ha tan (TDS)200500700

Rn ha tan c nh (FDS)120300400

Rn ha tan bay hi (VDS)80200300

Rn l lng (SS)100200300

Rn l lng c nh (FSS)205060

Rn l lng bay hi (VSS)80150240

Rn c th lng (SETS)4815

Vic xc nh cht rn l lng l v cng hu ch trong vic nh gi nhim nc. N c s dng rng ri xc nh nng ca nc thi sinh hot v nh gi c hiu qu ca qu trnh x l nc. Vic xc nh cht rn c th lng cng quan trng trong phn tch nc thi. N phc v cho vic nh l c s xc nh nn la chn phng php no x l nc thi. Trc y ngi ta dng tng cht rn xc nh mc nhim trong nc thi. Ngy ny kim tra cht lng nc c thay th bng vic kim tra ch s BOD, COD, c s dng nh gi chnh xc hn nng cht nhim trong nc thi. Gi tr ca tng cht rn l lng c th d dng xc nh c t vic o dn. Nng tng cht rn ha tan c ghi bng 4.6. Bi v cht rn c nh v d bay hi c lin quan n s lng cht v c v hu c hin din trong thnh phn cht rn ca nc thi, bn hot tnh v cht thi cng nghip, vic xc nh chng l hu ch trong vic kim sot hot ng nh my x l nc thi. Tuy nhin, vic xc nh BOD, COD v cacbon hu c s cung cp cc bin php tt hn trong o lng cc thnh phn hu c.Bng 4.6: Tng cht rn ha tan (TDS) trong 1 s mu ncLoi ncTDS (mg/L)

Nc bin35000

Khuyn co cho nc ung c