Làng nghề Vân Chàng

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Bi : nhim mi trng1. Thc Trng lng ngh Vn Chng Cch TP Nam nh kh xa ,khong hn 10km v pha Nam nhng lng ngh Vn Chng(TT Nam Giang, huyn Nam Trc, tnh Nam nh) mang m nt ca mt cm cng nghip si ng. n cha trong khng kh si ng y l sc sng ca mt vng qu hn nghn nm tui ang khng ngng vn ln bng chnh ngh truyn thng: ngh rn.Vn Chng l mt trong s t lng ngh ca Vit Nam tm c hng i cng t nc hi nhp v pht trin.

Lng ngh hn 700 tui Tng truyn, vo i vua Trn Nhn Tng (1279-1293), ngh rn c du nhp vo Vn Chng.Khi lng c 15 c t thuc 15 dng h gm on, Trn, V, Nguyn, , Ng... c su ng thy t ni khc n truyn dy. ghi nh cng lao, qu hng Vn Chng tn su ng thy dy ngh l Lc v Thnh s, lp n th lm Thnh hong ca lng.Hng nm ngi dn Vn Chng t chc hi lng vo ngy15/11 m lch tng nh cng n ng t a vo lng ngh rn Vn Chng c c nh ngy hm nay. Thi xa xa Vn Chng ch sn xut c mt s mt hng n iu mang tnh th cng nh dao, ko, bn l, inh, c vt, bp king, cuc xng, rng co... My chc nm tr li y, lng ngh Vn Chng tng bc pht trin. Sn phm ca h mt phn c c gii ha vi k ngh tinh xo, mu m p t bn cao trong s dng, nht l cc ph tng xe p. Chnh nh nhng mt hng ny, trn chc nm trc hai hp tc x Tn Tin v Tin Tin ca i phng tr thnh n v tin tin xut sc trong ngnh cng nghip tiu th cng nghip..

Lng ngh vn mnh thnh cm cng nghip Tng truyn, vo i vua Trn Nhn Tng (1279-1293), ngh rn c du nhp vo Vn Chng. Thi xa xa Vn Chng ch sn xut c mt s mt hng n iu mang tnh th cng nh dao, ko, bn l, inh, c vt, bp king, cuc xng, rng co... My chc nm tr li y, lng ngh Vn Chng tng bc pht trin. Sn phm ca h mt phn c c gii ha vi k ngh tinh xo, mu m p t bn cao trong s dng, nht l cc ph tng xe p. Chnh nh nhng mt hng ny, trn chc nm trc hai hp tc x Tn Tin v Tin Tin ca i phng tr thnh n v tin tin xut sc trong ngnh cng nghip tiu th cng nghip. Do c ch th trng, hai hp tc x c kh gii th, song ngh c kh Vn Chng li pht trin cha tng c. 95% s h trong lng vn tm huyt vi ngh; 2/3 s h, c s sn xut c trang b my mc. Tng gi tr my mc ca Vn Chng tiu th 40 n 45 tn ph liu c kim loi ln than, thu ht 1.000 n 1.200 lao ng t khp ni v. My mc a vo sn xut ngy mt nhiu, lm cho mt hng ca Vn Chng ngy mt phong ph, tn tin. Ring ko c my chc loi, cht lng tt. Mi my tht, my n, my nn Vn Chng mt ngy c th sn xut 150 m hoc xoong nhm, 100 i vnh hoc chn bn, 200-300 pan, 400-500 chn chng xe p. Mi ph liu c chuyn v Vn Chng, u tr thnh vt hu ch, t hiu qu s dng cao. Ngy ngy, hng ca Vn Chng i khp ni trong nc, sang c Lo, Campuchia. Hin Vn Chng c khong 200 h, thu nhp mi ngy 120 150 nghn ng. Vn Chng khng thiu ngi gii tay ngh v hu ht nhng tay ngh gii u c nh xng sn xut vi quy m t bn, nm n by, tm cng nhn. Nh th i sng ngi dn Vn Chng lun tng trng, nh ca xy ct khang trang, trong c 40% l cao tng, 90% s h c xe my, ti vi mu, khng cn h ngho. ng lng ng xm c b tng ha cao ro sch s. Lng c bn trm in, tng cng sut 2.000KVA, khong 400 my mc ln nh, hng thng tiu th hng nghn tn ph liu kim loi. i sng y ang i ln t ngh rn truyn thng. Lng c 80 ca hng dch v i sng, mt ch hp chiu, thng ngy lng thc, thc phm tiu th hng tn. Bi vy ngi Vn Chng i ti u lm giu ti . Ti qun Tn Bnh, thnh ph H Ch Minh, c c mt lng Vn Chng trn 300 h, khng t ngi c vn ln n hng t ng. H lin doanh vi nhiu ni trong nc v c vi ngi nc ngoi nh i Loan, Thi Lan, Singapo.

Nm 2005, Cm cng nghip Vn Chng c thnh lp trn c s lng ngh rn truyn thng Vn Chng tnh Nam inh. Cm cng nghip vi tng lai y ha hn Sau 5 nm quy hoch, Cm cng nghip Vn Chng c nhng bin i ng k v mt bng sn xut, phng thc sn xut, a dng ha sn phm v c bit l vn mi trng. i i vi s pht trin cng nghip l s suy thoi v mi trng ngy cng tr nn nghim trng,con sng Vn Chng ngy cng nhim bi hng ngy phi on mnh hng chu mt lng cht thi cng nghip ln..Quan tm n cuc sng ca ngi dn c quan chc nng u t hn 3 t ng xy dng cc cng trnh x l cht thi, cm cng nghip Vn Chng ang s hu mt h thng x l mi trng khp kn, hiu qu cao. ng Vn Dng, chuyn vin Phng Cng thng huyn Nam Trc, tnh Nam nh cho bit: Gi tr sn xut ca Cm cng nghip Vn Chng tnh thi im ny t khong 100-120 triu ng/ngy, li nhun trung bnh cho mi doanh nghip, c s sn xut khong 300 triu ng/nm. CCN Vn Chng ang thu ht c khong 2.500 lao ng c trong v ngoi a phng. Thu nhp cao ng thi gii quyt c s lng ln lao ng tht nghip trong vng,Vn Chng tr thnh khu vc pht trin nht trong huyn Nam Trc. Thnh cng trong gn gi lng ngh ca Vn Chng xut pht t nhiu nguyn nhn nhng quan trng hn c vn l yu ngh, say ngh ca cc th h ngi dn ni y.Nhiu ngi tr tui ni y tr thnh nhng ngi qun l gii da trn vic qun l v sn xut nhng mt hng m ng cha li. C l khc vi nhiu vt hu hnh khc, lng nhit huyt, gn b vi ngh cha ng ca bao lp ngi Vn Chng. khng b thi gian ph lp bi m mai mt. Lng ngh Vn Chng (Nam nh) i mt vi nhim Tng c truyn thng rt lu i, lng ngh Vn Chng (th trn Nam Giang, huyn Nam Trc, tnh Nam nh) l mt trong nhng lng ngh c kh ni ting. Ngh ny gp phn nng cao i sng ca ngi dn lng Vn Chng, vi thu nhp bnh qun 900 USD/ ngi/nm. Vn Chng - im sng Cm cng nghip lng ngh Nam nh

- m t trong r t nhiu cm cng nghip ng ngh ca t nh Nam nh, v i s n ng ng ca ngi dn, s gi p thi t thc t hot ng huy n cng, Vn Chng v ang vn n mnh m tr thnh m t im s ng v ph t trin cng nghip - tiu th cng nghip a phng. Nm 2005, Cm cng nghip (CCN) Vn Chng c thnh lp trn c s lng ngh rn truyn thng Vn Chng tnh Nam inh. Sau 5 nm quy hoch, CCN Vn Chng c nhng bin i ng k v mt bng sn xut, phng thc sn xut, a dng ha sn phm v c bit l vn mi trng. Vn l lng ngh rn truyn thng hn 400 nm tui, c thi k s pht trin mnh m nhng thiu quy hoch ca lng ngh, y Vn Chng ti nguy c thiu mt bng sn xut trm trng, cng vi l cc tc ng khng tt vi mi trng. Trc thc t , S Cng Thng tnh Nam nh phi hp vi Trung tm khuyn cng I, quy hoch CCN Vn Chng trn din tch 10,3ha v dnh cho cc DN, c s sn xut (CSSX) vo cm nhiu chnh sch u i nh: thi gian thu t, gi thu t, h tr xy dng c s h tng ban u Do vy, CCN Vn Chng thu ht 800 h ra thu t, dng xng vi hn 20 DN v khong 700 CSSX. M rng c mt bng sn xut, cc DN, CSSX trong CCN Vn Chng nhanh chng u t my mc, hin i ha qu trnh sn xut thay th dn phng thc sn xut th cng, km nng sut. V Vn Chng hm nay, khng cn cnh ngi dn thi la bng m, rn bng tay m c thay th bng my cn rt, my dp, my khoan, my tin, my mi, l nung C s chuyn mnh nh vy, ngoi n lc ca cc DN, CSSX cn c s gp sc khng nh t hot ng khuyn cng. Trung tm khuyn cng I ng ra bo lnh cho cc DN v CSSX vay vn t Ngn hng Nng nghip v pht trin nng thn vi mc li sut u i 12%/nm v s tin c vay t 100-150 triu ng/DN, i mi phng thc sn xut. Vi nhng thit b hin i mt phn c mua trong nc, mt phn nhp v t Trung Quc, Nht Bn cc DN, CSSX trong CCN Vn Chng chuyn sang chuyn mn ha sn xut. Mi DN, CSSX chuyn sn xut mt vi cng on, mt vi loi sn phm. iu ny khng ch gip nng cao nng sut lao ng m cn to s lin kt cng pht trin gia cc DN, CSSX. Vn Chng gi khng ch ni ting vi nhng sn phm truyn thng nh lim, cuc, inh, c vt m nhng sn phm c tnh chnh xc cao nh: ph tng xe

my, xe p, cc b phn ca my gt, ni hi hay nhng gia dng nh: dao, ko, chu thau cng rt c tin dng. ng Vn Dng, chuyn vin Phng Cng thng huyn Nam Trc, tnh Nam nh cho bit: Gi tr sn xut ca CCN Vn Chng tnh thi im ny t khong 100-120 triu ng/ngy, li nhun trung bnh cho mi DN, CSSX khong 300 triu ng/nm. CCN Vn Chng ang thu ht c khong 2.500 lao ng c trong v ngoi a phng. Ngay t khi quy hoch CCN Vn Chng, vn mi trng c S Cng Thng tnh Nam nh, Trung tm khuyn cng I, UBND th trn Nam Giang c bit ch trng. Bi trong qu trnh sn xut, ngh c kh ca Vn Chng to ra rt nhiu bi, ha cht, nc v rc thi V vy, cc cng trnh x l cht thi ca CCN Vn Chng, bao gm: hai h lng, hai b cha v x l rc thi, h thng thot nc quanh CCN lun c cc cp chnh quyn ch trng kim tra. Ngoi ra, Trung tm khuyn cng I cng phi hp vi cc DN, CSSX t chc nhng lp o to, nng cao k nng an ton lao ng, pht bo h cho ngi lao ng Vi ngun vn u t hn 3 t ng xy dng cc cng trnh x l cht thi, CCN Vn Chng ang s hu mt h thng x l mi trng khp kn, hiu qu cao. Nhng cng vi s pht trin, ngi dn ni y ang phi i din vi nhng nguy c nhim mi trng, bnh tt. Khi nh cng ni sn xu t

Hin ti, lng Vn Chng c 875 h vi 3.450 nhn khu nhng c ti 700 h lm ngh c kh truyn thng. Nhng sn phm do ngi dn lng ngh Vn Chng lm ra cng rt phong ph. T cuc, xng, xoong, ni n nhng vt liu xy dng nh thp, ca hoa, bn l... thm ch c ph tng xe p, xe my. Hu ht mi nh u c mt xng sn xut. Nh ng Trn Vn Vn, mt ngi dn trong lng, vi din tch t l 150m2, nhng c ti 100m2 dng lm c s sn xut xoong, ni. tit kim din tch, nhng nguyn vt liu ngn ngang di sn. Nhng bao ti than dng lm cht t c xp t ngoi cng n tn trong nh. Thm ch, chng li c t ngay cnh phng ng. Anh Trn Trng Hng, Ph Ch tch UBND th trn Nam Giang cho bit: Din tch hp, nn ngi dn trong lng phi tn dng din tch t ca mnh dnh cho sn xut, thng chim ti 2/3 din tch t . Hu ht, h thng nc thi c thi chung ging nh nc thi sinh hot. V vy, nhng cng rnh nc thi ca ngi dn ni y lun c mt mu vng, c st.

Theo iu tra ca Vin Cng ngh sinh hc, mi trng ti Vn Chng: Hm lng bi khu vc sn xut vt qu 3 ln tiu chun cho php; kh SO2; CO; No vt qu 5 ln ti khu trung tm, ting n vt qu 10-11 ln. Nc thi ra con knh Vn Chng, cha c x l , trong c cha nhiu ho cht nguy him, c bit hm lng cht c Cyanua vt 65-117 ln tiu chun cho php. Bc s V Vn Sn, Trm y t th trn Nam Giang, cho bit: Tnh t nm 2007 n 5 thng u nm ca 2008, c 14.678 lt ngi Vn Chng n khm. Trong s , bnh vim phi, vim ph qun, bnh ngoi da l nhng bnh ch yu ngi mc phi. Ch tnh ring lng Vn Chng c 743 ngi mc bnh vim phi; 864 ngi mc bnh vim ph qun; 357 ngi mc bnh ngoi da, v 790 ngi mc cc bnh khc. Cng theo iu tra cho thy, tui th trung bnh ca ngi dn Vn Chng l 55 tui, thp hn nhiu so vi mc bnh qun ca c nc. Lng ngh c kh Vn Chng (Nam nh) nhim t, ngun nc v khng kh lm cho phn ln c dn trong lng mc cc bnh v ng h hp, bnh ngoi da v ph khoa, 4,7% s ngi trong lng b mc bnh lao phi, 8,3% mc bnh vim ph qun, s ngi cht v ung th ngy cng tng. iu ng lu l tr em sng lng c t l mc cc bnh vim phi, vim ph qun, tiu chy, ci hn so vi tr em cc lng khc C khu lng m mt khi bi, ngt ngt vi ting ba, ting my t, dp, v hm hp nng. Ngi dn Vn Trng (Nam Trc, Nam nh) thng ni, nu ra tay bng nc ma trn mi nh xung th 15 pht sau da s b phng rp do axit st n da v kim loi nng ngm vo. Hn 400 nm tn ti, lng ni ting giu c nh ngh c kh, hng st, m, c nhm truyn thng. Nhng cng vi s pht trin kinh t, dn lng lm mc nhim tng cao. Theo S Khoa hc Cng ngh Mi trng Nam nh, Vn Chng b nhim nng nht trong s 15 lng ngh nhim loi 1 ca tnh. Lng bi l lng trong khng kh mc 4,28 mg/m3 vt tiu chun cho php 5-10 ln. Nhit trung bnh trong khu vc sn xut lun mc bo ng trn 38,5 C. Phn ln cc c s sn xut t ngay trong cc khu dn c, nh xng cht hp, h thng cng dn thot nc thi cha c quy hoch v khng m bo v sinh cng nghip. 30 l b rng rc chy sut ngy m, 346 my t, dp, khoan, tin, hng

chc my ba, cn nhm hot ng ht cng sut tiu th t 50-70 tn st, nhm... v 400 kg ho cht khin lng ngy cng ngt ngt. Mc nhim t, ngun nc v khng kh nng lm cho phn ln c dn Vn Trng mc cc bnh v ng h hp, da liu v ph khoa. Theo i V sinh phng dch x, tui th ca dn lng l 55, 150 ngi mc bnh lao phi (4,7%), 246 ngi mc bnh vim ph qun (8,3%), 80 ngi au mt ht, s ngi cht v ung th phi ngy mt tng ln. ng on Hu Minh, mt ngi dn lng, cho bit do khng kh v cng bc bi, kh chu nn ma ng d tri c rt n my nh ng vn phi bt qut lm tn hi nhim."Gia nh ti khng c ai trnh c bnh vim mi, au mt", ng Minh bc xc cho bit. Trc tnh trng ny, UBND x Nam Giang b tr mt khu t rng 2.000 m2 xy dng nh xng tin cho vic qun l v x l nhim mi trng nhng mi ch c rt t h tch sn xut ra khi khu dn c. Bi n t ng ca Cm cng nghip ng trc thc trng , UBND th trn Nam Giang tin hnh nhiu bin php tch cc gim thiu nhim lng ngh. Mt trong nhng bin php c coi l hiu qu gim thiu nhim mi trng ti lng Vn Chng l dch chuyn lng ngh sang sn xut ti Cm cng nghip. D n xy dng Cm cng nghip c khi cng nm 2002, hon thnh nm 2004 vi din tch 30 hecta c chia thnh 2 giai on. Tuy nhin, mi hon thnh giai on 1 vi din tch 14 hecta a vo s dng. Vi s u t ca UBND tnh cng nh s ng gp ca ngi dn trong lng Vn Chng, mt cm cng nghip ca lng ngh ra i. C s vt cht nh h thng cng rnh, h thng x l nc thi... c xy dng mt cch y v khoa hc. Tnh n nm 2003, c 72 h sn xut kinh doanh n khu cng nghip sn xut. Cng vi vic nhp vo cm cng nghip, cc h ny ko theo c gia nh ra sinh sng. Do vy li m rng thm din tch b nhim v vic hn ch ngi dn tip xc vi nhng cht thi c hi tht bi. Do vy, k hoch xy dng giai on 2 cng nh " sp x". Cho n nay, tnh trng nhim mi trng ti lng ngh Vn Chng vn l mt bi ton cha c li gii p

M hnh x l kh thi v nc thi nguy hi do Cng ty c phn Cng ngh thn thin mi trng Bch Khoa (Trng i hc Bch Khoa H Ni) thit k, lp t theo hp ng vi Cc Kim sot nhim, va c bn giao l nc thi i gia nh ng Nguyn i bc lng ng Ci ti lng ngh Vn Chng v ng Ci (Nam nh). Sau khi nhn trch nhim t vn thit k m hnh, Cng ty tin hnh kho st thc t tnh hnh thc hin x l kh thi lng ngh Vn Chng. Kt qu kho st cho thy, hin trng kh thi lng ngh Vn Chng cao hn rt nhiu so vi tiu chun an ton Y t v TCVN 6993 - 2001 (bi tng gp hn 3 ln, kh SO2 gp 1,6 ln, CO gp hn 3 ln, hp cht amoni gp gn 4 ln ). Tng t nh vy nc thi lng ngh Vn Chng cng ang mc bo ng. Trc thc t , Cng ty c phn Cng ngh thn thin mi trng Bch Khoa thit k m hnh th im ti h gia nh ng V Nam Xun chuyn sn xut mm nhm. Ton b hn hp kh thi cha hi kim, hi axt pht sinh ti cc v tr x l b mt nhm c h thng thu gom vo thit b ra kh (thp hp th) thc hin qu trnh tch bi v x l cc thnh phn gy nhim mi trng. Kh thi sau x l t chun c thi ra mi trng bng ng khi. Hi dung mi v dung dch x l thu ti y thit b c tch bn v b sung ha cht theo nh k . x l nc thi nguy hi c cha kim, axit pht sinh trong qu trnh x l b mt sn phm nhm gia dng ti nh ng V Nam Xun, Cng ty Lp t thit b x l nc thi ng b vi thit b x l kh. Thit b ny gm b x l 3 ngn thu gom nc thi mang tnh axt, kh crm 6 (ngn 1), nc c tnh kim (ngn

2). Sau nc thi c x l cc thnh phn gy nhim ti ngn th 3, nc sau x l c chuyn sang b cha ti s dng hoc bm tun hon vo thit b x l kh thi. Cng thi im ny, Cng ty cn thit k, lp t m hnh th nghim x l nc thi sau m ti gia nh anh Nguyn i Bc, lng ngh ng Ci. Dng nc thi cha kim v dng nc thi cha axt v Crom c dn vo 2 b khc nhau. B cha axit v crm, s dng lp phoi x st kh crm 6 thnh crm 3. Nc thi sau khi qua hai b cha c tp trung vo b iu ha n nh v iu ha lu lng nc thi. Khi a sang thit b hp khi, nc thi c b sung dung dch kim iu chnh pH v kt ta kim loi c trong nc thi; sau nc thi s t chy sang ngn lng tch bn. Nc thi sau khi thu v b cha c bm tip sang thit b lc ni gi li cc cht hu c ha tan, cc cht mu cn st trong dng thi. Nc thi sau x l t quy chun c thu vo bn cha nc sch s dng li. Bn thi lng ti y thit b hp khi c ht sang sn phi bn. iu ng mng l cc h gia nh lp t m hnh x l th im hi dung mi, nc thi nguy ti hai lng ngh u hi lng vi thit b. ng V Nam Xun cho bit, trc y gia nh ng tham gia d n x l kh thi lng ngh Vn Chng, nhng thit b khng c bn vng "thit b x l hi nhim ln ny c thit k gn nh, chc chn, hiu qu tt; thit b x l nc thi nguy hi cng n gin, d s dng". Cn anh Nguyn i Bc cho rng, thit b x l nc thi nguy hi sau m lp t ti gia nh anh khng tn km lm, li ti s dng c nc thi. Tuy nhin, iu ng lo ngi nht l vic nhn rng cc m hnh x l kh, nc thi nhim ny ra ton a bn. Ngi dn lng ngh th trn Nam Giang khng thiu tin, nhng h chp thun b tin vo x l nhim l kh. Ngoi vic nng cao nhn thc, a trch nhim x l kh thi, nc thi t tiu chun mi trng vo hng c lng ngh, cn cn s rng buc cht ch ca php lut. ng Trn Trng Hng, Ph Ch tch th trn Nam Giang tha nhn m hnh ny ph hp vi quy m h gia nh nhng vn ni " Nu c Nh nc h tr khong 30% kinh ph th d trin khai". B n cnh tnh Nam nguy hi: nh: Ch ng hp t c quc t gii quy t r c thi

D n "Qun ch t thi nguy hi Nam nh" t th ng 08/2003 n th ng 05/2007 s hp t c trc ti p ca S TN&MT Nam nh v i C quan Hp

t c v Ph t trin Thy S. V i nhng phn tch v th ch v hung ph p , cng v i vic xy dng chi n c, hoch thc hin chi n c ny, Nam nh ang ti p cn c ch gii quy t v n hc b a ny m t c ch tng th... D n "Qun l cht thi nguy hi Nam nh" t thng 08/2003 n thng 05/2007 l s hp tc trc tip ca S TN&MT Nam nh vi C quan Hp tc v Pht trin Thy S. Vi nhng phn tch v th ch v khung php l , cng vi vic xy dng chin lc, k hoch thc hin chin lc ny, Nam nh ang tip cn cch gii quyt vn hc ba ny mt cch tng th... Ngi dn lng ngh Vn Chng "d th" hn... Lng Vn Chng cch thnh ph Nam nh 10 km v pha Nam, hi c th trn Nam Giang v sng Kinh Lng tr thnh tr ph. Nhng cuc sng ngi dn cng ngn li bi cht thi c hi cha y axit v st t ngh c nhm truyn thng su, by trm nm li. Ti liu t nhiu cuc kho st ca S TN&MT tnh, Vin a cht v trng i hc Greifwald (c) cho thy nhim t ngh c nhm khin cho tui th bnh qun ca ngi dn Vn Chng khng qu ngng 55. By gi th ngi lm ngh c th th d dng. Sn phm ni nhm c ln ca gia nh ch V Th Dung, ngi xm c Long c h thng lu thng a ti Kon Tum, k Lk, thm ch Lo, Campuchia. Ging nh tt c ngi dn Vn Chng, gia nh ch tch cc tham gia d n, t nhng bui hc tp ti vic ng gp tin xy dng h thng thot nc thi kn t gia nh qua xm, qua lng vo 2 h sinh hc tp trung. Hn th, ch cn l h t nguyn ng k sn xut sch hn, v l mt trong 3 gia nh tham gia tiu d n ny. Dy chuyn sn xut ca gia nh ch vn th cng. Nhng c mt ng khi cao 8 mt ht kh thi t ni nu st ln cao; st ri vi c hng li khng cho nhim xung cng rnh; mt h ga 2 ngn s lc nc thi trc khi theo ng ng chy vo cng chung ca lng; nhng chic thng xanh cha st v a xt do d n cp... Tt c nhng chi tit cha phi l cng ngh gip cho gia nh ch tit kim nguyn liu, khng thi cht nhim ra t, v "y" kh c ln cao. By gi th thn Vn Chng c hng c bo v mi trng lng ngh, t thu gom cht thi, c h thng cng cp I thu gom ton b nc thi lng ngh ra h sinh hc, c kho cha cht thi nguy hi... Mi vic vn cn pha trc Cng thi im ny D n tin hnh lp danh mc cht thi nguy hi t cc c s cng nghip, cc im nng, tnh ton khi lng cht thi nguy hi v s lng pht sinh n 2015 trn a bn ton tnh. ng thi thit lp chin lc qun l cht thi nguy hi c li cho mi trng, c UBND tnh ph duyt vo ngy 25/12/2006. Chng trnh gim thiu cht thi c thc hin thng qua cc tiu d n v Chng trnh sn xut sch hn. 24 doanh nghip tham gia chng trnh u t dy chuyn sn xut gim lng cht thi ra mi trng, ci tin qun l , tit kim 2,2 t ng cho doanh nghip v hn ch ng k ngun thi nguy hi. Tuy nhin y mi l nhng cng vic c tnh khi im .i vi tiu d

n Ci thin iu kin sn xut, mi trng v sc khe cho lng ngh Vn Chng c coi l thc hin thnh cng nht ca d n n thi im ny, vn cn nhiu vn phi tip tc trin khai. Bi l theo ng Trn Trng Hng, Ph Ch tch th trn Nam Giang, d n ny mi gp phn "y kh" ra khi Vn Chng v "dn" nc thi nguy hi vo h sinh hc. gii quyt trit cn rt nhiu cng sc, tin ca, tr tu ca cc nh khoa hc. Tnh Nam nh c thc chun b cc iu kin tip tc thc hin k hoch chin lc x l cht thi nguy hi. Nu C quan Hp tc v Pht trin Thy S tip tc ng gp tr lc i vi chng trnh ny trong thi gian ti, vn x l cht thi nguy hi Nam nh s c c hi thnh cng. Vn cn pha tr c Cng thi im ny D n tin hnh lp danh mc cht thi nguy hi t cc c s cng nghip, cc im nng, tnh ton khi lng cht thi nguy hi v s lng pht sinh n 2015 trn a bn ton tnh. ng thi thit lp chin lc qun l cht thi nguy hi c li cho mi trng, c UBND tnh ph duyt vo ngy 25.12.2006. Chng trnh gim thiu cht thi c thc hin thng qua cc tiu d n v Chng trnh sn xut sch hn. 24 doanh nghip tham gia chng trnh u t dy chuyn sn xut gim lng cht thi ra mi trng, ci tin qun l , tit kim 2,2 t ng cho doanh nghip v hn ch ng k ngun thi nguy hi. i vi tiu d n "Ci thin iu kin sn xut, mi trng v sc kho cho lng ngh Vn Chng" c coi l thc hin thnh cng nht ca d n n thi im ny, vn cn nhiu vn phi tip tc trin khai. Bi l, theo ng Trn Trng Hng, Ph Ch tch th trn Nam Giang, d n ny mi gp phn "y kh" ra khi Vn Chng v "dn" nc thi nguy hi vo h sinh hc. gii quyt trit cn rt nhiu cng sc, tin ca, tr tu ca cc nh khoa hc. Tnh Nam nh c thc chun b cc iu kin tip tc thc hin k hoch chin lc x l cht thi nguy hi. Nu C quan Hp tc v Pht trin Thu S tip tc ng gp tr lc i vi chng trnh ny trong thi gian ti, vn x l cht thi nguy hi Nam nh s c c hi thnh cng Mt trong cch nhm gim thiu nhim lng ngh Vn Chng l a ra cc cch s l mc nhim ngun nc hay vn gii quyt nc thi c thi ra t lng ngh B.N c thi v phn oi n c thi

I. N c v vai tr ca n c: Nh c nc, s sng trn tri t c hnh thnh, tn ti v pht trin t xa xa cho n nay. Nc chnh l ngun gc ca s sng. Cc qu trnh sng c thc hin rt phc tp v chng ch c th din ra trong iu kin c s tham gia ca nc. Nc l cht lng trong sut, khng mu, khng mi, khng v, nc c nhng tnh cht vt l v ho hc khc hn so vi cc cht lng khc. Nc l loi cht duy nht n ra khi ng bng, bng li ni trn mt nc, iu ny dn n hin tng phn tng nhit trong cc h v bin c. Nhit dung ring ca nc ln nht so vi mi cht lng v cht rn nn qu trnh un nng v lm ngui nc cng lu hn. Chnh v th, s sng din ra trong nc khng b bin ng t ngt v nhit. Nhit ha hi ca nc cng cao nht so vi tt c cc cht lng khc. Do , hi nc tch lu mt lng nhit ln v gii phng khi ngng t. V vy, nc l yu t chnh nh hng n kh hu ton cu. V mt ho hc, nc l hp cht c kh nng tham gia vo nhiu loi phn ng. Nc ho tan cc cht nhiu hn bt k mt dung mi no khc. Nc cng l tc nhn tham gia vo nhiu phn ng ho hc. Nc ho tan kh xy nhiu hn bt k cht lng no (1 lt nc 200C ho tan c 31 ml kh xy). V th, s sng xut hin trong lng ao, h, sng ngi, bin c v y i dng. Nc c mt trong cc c th sng v mang dinh dng n tt c cc t bo sng. C th ni, nc tham gia vo vic vn chuyn tt c cc cht tan i khp sinh quyn. Chu trnh vn ng ca nc trong t nhin din ra theo mt vng tun hon. Hi nc bc ln t i dng c khng kh mang vo t lin ho cng vi hi nc bc ln t ao, h, sng sui v s thot nc t thc vt, ng vt ngng t to thnh ma hoc tuyt ri xung mt t, lng nc cn li ch yu theo cc ngun nc mt hoc nc ngm chy ra bin v i dng. Nc l nguyn liu c bit, khng cht no c th thay th c. Nc l ngun ti nguyn v cng qu gi ca mi quc gia. Tng tr lng nc trn tri t rt ln (1.386 triu km3), nhng nc ngt v nc sch dng cho con ngi th c

hn v s ti to li dng nh phn b khng u v khng kp cho nhu cu s dng. Nc ngt ch chim khong 2,7% tng lng nc trn tri t; trong nm dng bng 77,22%, nc ngm 22,42%, h m 0,35%, sng sui 0,01% lng nc ngt. Ngun nc ngm thng c xu hng gim do khai thc nhiu m khng c b sung kp thi. Con ngi phi dng nc cho sinh hot v sn xut. Trong i sng, ng vt c th cht nu b mt t 10% n 20% lng nc trong c th. Trung bnh mi ngy, mt ngi cn a vo c th (qua n, ung nc) t 2,5 n 4 lt nc, cn nc dng cho sinh hot ca mt ngi li ln hn nhiu. X hi cng pht trin th nhu cu nc cho sinh hot cng tng ln. Nhu cu nc dng sn xut ra mt tn bn hoc bnh ph trung bnh cn 10 m3 nc, sn xut mt tn thp cn khong 25 m3, cn sn xut 1 tn giy cn ti 100 m3 nc. II. Nc thi: Hin chng Chu u nh ngha nc nhim nh sau: nhim nc l s bin i ni chung do con ngi i vi cht lng nc, lm nhim bn nc v gy nguy him cho con ngi, cho cng nghip, nng nghip, nui c, ngh ngi, gii tr, cho ng vt nui v cc loi hoang d. Theo Tiu chun Vit Nam 5980-1995 v ISO 6107/1-1980: Nc thi l nc c thi ra sau khi s dng hoc c to ra trong mt qu trnh cng ngh v khng cn gi tr trc tip i vi qu trnh . Ngi ta cn nh ngha nc thi l cht lng c thi ra sau qu trnh s dng ca con ngi v b thay i tnh cht ban u ca chng. Thng thng nc thi c phn loi theo ngun gc pht sinh ra chng. cng l c s trong vic la chn cc bin php gii quyt hoc cng ngh x l . * Nc thi sinh hot: l nc thi t cc khu dn c, khu vc hot ng thng mi, khu vc cng s, trng hc v cc c s tng t khc. * Nc thi cng nghip (hay cn gi l nc thi sn xut): l nc thi t cc nh my ang hot ng hoc trong nc thi cng nghip l ch yu. * Nc thm qua: l lng nc thm vo h thng ng bng nhiu cch khc nhau, qua cc khp ni, cc ng c khuyt tt hoc thnh h ga hay h x. * Nc thi t nhin: nc ma c xem nh nc thi t nhin nhng thnh ph hin i, chng c thu gom theo h thng ring.

* Nc thi th: nc thi th l mt thut ng chung ch cht lng trong h thng cng thot ca mt thnh ph, th x; l hn hp ca cc loi nc thi trn. Tnh cht c trng ca nc thi sinh hot v nc thi th c trnh by bng I. Bng trc gic, con ngi c th nhn thy c cc cht ho tan trong nc thi c hm lng tng i cao. Nc thi c nhng biu hin c trng sau: * c: Nc thi khng trong sut. Cc cht rn khng tan to ra cc huyn ph l lng. Cc cht lng khng tan to dng nh tng l lng hoc to vng trn mt nc. S xut hin ca cc cht keo lm cho nc c nht. * Mu sc: Nc tinh khit khng mu. S xut hin mu trong nc thi rt d nhn bit. Mu xut pht t cc c s cng nghip ni chung v cc s s ty nhum ni ring. Mu ca cc cht ho hc cn li sau khi s dng tan theo ngun nc thi. Mu c sinh ra do s phn gii ca cc cht lc u khng mu. Mu xanh l s pht trin ca to lam trong nc. Mu vng biu hin ca s phn gii v chuyn i cu trc sang cc hp cht trung gian ca cc hp cht hu c. Mu en biu hin ca s phn gii gn n mc cui cng ca cc cht hu c. * Mi: Nc khng c mi. Mi ca nc thi ch yu l do s phn hu cc hp cht hu c trong thnh phn c nguyn t N, P v S. Xc ca cc vi sinh vt, thc vt c Prtin l hp cht hu c in hnh to bi cc nguyn t N, P, S nn khi thi ra bc mi rt mnh. Cc mi: khai l Amniac (NH3), tanh l cc Amin (R3N, R2NH-), Phophin (PH3). Cc mi thi l kh Hir sunphua (H2S). c bit, cht ch cn mt lng rt t c mi rt thi, bm dnh rt dai l cc hp cht Indol v Scatol c sinh ra t s phn hu Tryptophan, mt trong 20 Aminoaxit to nn Prtin ca vi sinh vt, thc vt v ng vt. * V:

Nc tinh khit khng c v v trung tnh vi pH=7. Nc c v chua l do tng nng Axt ca nc (pH7). Cc c s cng nghip dng Baz th li y pH trong nc ln cao. Lng Amniac sinh ra do qu trnh phn gii Prtin cng lm cho pH tng ln. V mn cht l do mt s mui v c ho tan, in hnh l mui n (NaCl) c v mn. Bng I: Cc tnh cht c trng ca nc thi v ngun gc ca chng * Nhit : Nhit ca nc s thay i theo tng ma trong nm. Nc b mt Vit Nam dao ng t 14,3-33,50C. Ngun gc gy nhim nhit chnh l nhit ca cc ngun nc thi t b phn lm lnh ca cc nh my, khi nhit tng ln cn lm gim hm lng xy ho tan trong nc. * dn in: Cc mui tan trong nc phn li thnh cc ion lm cho nc c kh nng dn in. dn in ph thuc vo nng v linh ng ca cc ion. Do vy, dn in cng l mt yu t nh gi mc nhim nc. * DO (lng xy ho tan): DO l lng xy ho tan trong nc cn thit cho s h hp ca cc sinh vt sng di nc (c, lng th, thu sinh, cn trng ). DO thng c to ra do s ho tan t kh quyn hoc do quang hp ca to. Nng xy t do trong nc nm khong 8-10 mg/l v dao ng mnh ph thuc nhiu vo nhit , s phn hu ho cht, s quang hp ca to Khi nng DO thp, cc loi sinh vt trong nc gim hot ng hoc cht. Do vy, DO l mt ch s quan trng nh gi s nhim nc ca cc thu vc. * Ch tiu vi sinh vt: Nc thi cha mt lng ln cc vi khun, vi rt, nm, ru to, giun sn... nh gi mc nhim bn bi vi khun, ngi ta nh gi qua mt loi vi khun ng rut hnh a in hnh c tn l Cli (NH4Cl). Cli c coi nh mt loi vi khun v hi sng trong rut ngi, ng vt. Cli pht trin nhanh mi

trng Glucoza 0,5% v Clorua amoni 0,1%; Glucoza dng lm ngun nng lng v cung cp ngun Cacbon, Clorua amoni dng lm ngun Nit. Loi c hi l vi rt. Mi loi vi rt u sng k sinh ni t bo. Bnh thng khi b dung gii, mi con Cli gii phng 150 con vi rt. Trong 1 ml nc thi cha ti 1.000.000 con vi trng Cli. Ngoi vi khun ra, trong nc thi cn c cc loi nm meo, nm mc, rong to v mt s loi thu sinh khc... Chng lm cho nc thi nhim bn sinh vt. III. Cc phng php x l nc thi: * X l c hc: Phng php x l c hc s dng nhm mc ch tch cc cht khng ho tan v mt phn cc cht dng keo ra khi nc thi. Phng php x l c hc c th loi b c n 60% cc tp cht khng ho tan trong nc thi sinh hot v gim BOD (nhu cu xy sinh ho) n 20%. Thng thng, x l c hc ch l giai on x l s b trc khi cho qu trnh x l sinh hc. * Phng php x l ho - l: Thc cht ca phng php x l ho - l l a vo nc thi cht phn ng no gy tc ng vi cc tp cht bn, bin i ho hc, to thnh cht khc di dng cn hoc cht ho tan nhng khng c hi, khng gy nhim mi trng. V d phng php trung ho nc thi cha Axt, Baz, phng php xy ho... Phng php ho l c th l gii php cui cng hoc l giai on x l s b cho giai on tip theo. * Phng php x l sinh hc: Phng php ny thng dng loi cc cht phn tn nh, keo v hu c ho tan (i khi c v c) khi nc thi. Nguyn l ca phng php l da vo hot ng sng ca cc vi sinh vt c kh nng phn hu, b gy cc i phn t hu c thnh cc cht n gin hn, ng thi chng cng s dng cc cht c trong nc thi lm ngun dinh dng nh Cacbon, Nit, Phtpho, Kali... Qu trnh x l sinh hc trong iu kin nhn to c th t mc hon ton (x l sinh hc hon ton) vi BOD gim ti 90-95% v khng hon ton vi BOD gim ti 40-80%. Phng php sinh hc l phng php trit nht, n to ra nhng sn phm thn thin vi thin nhin hoc bin i nhng cht c hi tr thnh hu ch. Ngy nay,

phng php sinh hc v ang c nghin cu, p dng x l nhim mi trng C. xu t phng ph p x n c thi

S CC QUI TRNH X S dng b t hoi v bi lc ngm x l s b nc thi sinh hot

Phn thit k b t hoi v bi lc ngm s c trnh by k trong mn X L Nc Thi II. Cc qui trnh x l nc cng rnh hoc nc thi cc nh my cng nghip

Nc thi Bn hoc cht rn

1.TI S DNG NC THI Nc thi nu khng c x l ng mc s gy nhim mi trng. Tuy nhin trong nc thi sinh hot c cha mt lng kh ln nng lng, m v cc cht khong nh kali, photpho, canxi... l nhng phn bn c gi tr i vi nng nghip. Cho nn vic ti s dng cc gi tr ny ca cht thi s gp phn bo v ti nguyn thin nhin v bo v mi trng. Mc tiu ca vic ti s dng cht thi hu c l x l cc cht thi v gi li cc cht dinh dng c gi tr ti s dng. Cc cht dinh dng ny gm Carbon, Nitrogen, Phospho v cc khang vi lng. Chng c ti s dng : Sn xut nng nghip Cc cht thi hu c c th s dng lm phn bn hoc ci to t. Tuy nhin, nu s dng cht thi cha c x l th t c hiu qu khng cao bi v cy trng ch hp thu cc cht dinh dng dng v c (v d NO3- v PO43-), cc vi khun v k sinh trng trong cht thi cha c x l c th ly nhim cho ngi s dng hoc tiu th cc sn phm. Qu trnh phn hy hiu kh hay ym kh bin i cc cht thi hu c thnh cc cht v c thch hp cho cy trng v tiu dit phn ln cc vi khun v k sinh trng. Sn xut Biogas Biogas, mt sn phm ca qu trnh phn hy ym kh cc cht hu c, c xem l mt ngun nng lng ti ch thay th du ha, ci... Biogas l mt hn hp kh bao gm methane (khong 65%), CO2 (khong 30%) v mt t NH3, H2S v cc

cht kh khc. Nng lng ca Biogas ch yu l t kh methane. Methane c nhit tr l 1012 BTU/ft3 (hoc 9.005 Kcal/m3) 15.5oC v 1 atm. Nhit tr ca Biogas khong 500 700 BTU/ft3(4.450 6.230 Kcal/m3). i vi hm Biogas loi nh (1 5 m3) lp t cho cc h gia nh x l cht thi sinh hot hay phn gia sc, Biogas c s dng un nu, thp sng v si m. i vi hm Biogas loi ln dng x l nc thi cng nghip hoc ca cc tri chn nui ln, Biogas c s dng un nc cho cc ni hi, hoc chy cc ng c t trong. Cht thi ca hm Biogas giu cht dinh dng l mt ngun phn bn c gi tr. Nc thi c dng nui to hoc phiu sinh ng vt (Moina) lm thc n cho c hoc bn thng xung ao c. Cht thi rn c phi kh ri ri trn ng rung, hoc bn cho ao c. Sn xut thy sn nhng vng nhit i cht thi hu c c ti s dng trong sn xut thy sn qua 3 hot ng chnh sau:

Sn xut to (m n bo). Phiu sinh thc vt (macrophytes, bo, lc bnh) Nui c

Ti s dng gin tip Khi nc thi c thi trc tip ra sng rch, qu trnh "t lm sch" ngun nc do hot ng phn hy v c nh cc cht hu c trong nc thi ca vi khun c sn trong t nhin s din ra. Do h lu cch xa ngun thi mt khong cch nht nh ngi ta c th s dng ngun nc ti tiu cho cy trng m khng lm nhim mi trng.

1. X n c thi bng phng ph p sinh hc, cn gi l h thng x l phn ng sinh hc nh git. Quy trnh hot ng ca h thng l cho dng nc thi i t trn xung di, xuyn qua mt lp vt liu tip xc nh v nh c cha vi sinh phn hy cc cht nhim trong nc thi. Kt qu qu trnh phn hy s to ra CO2 , H2O v sinh khi. Vi sinh hu c trn cht nn c cung cp xy vi p lc thp bi qut gi n gin thi khng kh t bn di ca b phn ng. Nh c ch ny m cc ht vt liu c y chuyn ng lin tc tip xc vi cc cht thi, tiu th nng lng rt thp. Theo TS Lutz Haldenwang, Trng Phng Cng ngh sinh hc ca DAS, nh thit k t ng, h thng c kh nng vt lng sinh khi d mt cch u n ty theo thi gian c ci t sn. Mt u im khc l b phn ng v ng ng c lm bng nha polyethylene nn khng cn bo v chng n mn, gip tit kim chi ph. H thng ny c th c p dng trong cc ngnh dt nhum, ha cht, phn bn, dc phm, thc phm v nc ung.. X NC THI BNG PHNG PHP SINH HC a.S DNG AO H X NC THI

C c oi ao h thng s dng v c im ca n Phn Tn thng C c c im C c ng dng

oi Hiu kh

dng a) H x l chm c thit k sao cho iu kin hiu kh t c sut chiu su ca ao, h. X l cht hu c ha tan v nc thi qua x l s cp

b) H cao tc

c thit k Loi cc cht dinh t sn lng cao. dng, cht hu c ha tan Ging nh h x l chm nhng lu lng np cht hu c rt thp Su hn h x l cao tc; thit b thng kh v qu trnh quang hp cung cp oxy cho h thng lp nc mt; lp gia l qu trnh k kh khng bt buc; lp y h l qu trnh k kh X l cp ba nc thi t h thng x l th cp t cht lng cao hn X l nc thi qua lc hoc cha qua lc, nc thi cng nghip

c) H x l cp ba

Kt hp H hiu Facultative kh-k c thng kh kh (c thng kh)

Kt hp H hiu kh facultative - k kh (ngun oxy t to) K kh H x l k kh

Ging nh trn nhng khng c thit b thng kh

X l nc thi qua lc hoc cha qua lc, nc thi cng nghip

iu kin k kh trong ton h, thng c thm h hiu kh hoc facultative x l tip nc thi sau giai on k kh ny.

X l nc thi th, nc thi cng nghip

K kh H thng h kt hp x l vi k kh hiu kh

Kt hp gia cc loi h nu trn. Thng c thm giai on hon lu nc t h hiu kh sang h k kh.

X l trit nc thi th vi hiu sut kh vi sinh vt gy bnh cao.

Ngun: Wastewater Engineering: treatment, reuse, disposal, 1991 C c thng s tham ho trong qu trnh thi t

Thng s HK x l chm Ch np nc thi Cch khong c khuy trn HK cao tc Cch khong c khuy trn HK x l cp ba Cch khong c khuy trn 2 10

oi H Facultative B H k kh Thng kh c hc Khuy trn trit

Khuy trn trn b mt

Din tch h (acre) Vn hnh

< 10

0,5 2

2 10

0,5 2

2 10

ni tip hoc song song 10 40

ni tip

ni tip hoc song song

ni tip hoc song song

ni tip

ni tip hoc song song

Thi gian lu tn nc (ngy) Su, ft pH Nhit hot ng

46

5 20

5 30

20 50

3 10

34

1 1,5

35

48 6,5 8,5 0 50

8 16 6,5 7,2 6 50

6 1 20 6,5 8,0 0 30

6,5 10,5 6,5 10,5 6,5 10,5 0 30 5 30 0 30

(oC) Nhit ti u (oC) Lu lng np BOD (lb/acre.d) Hiu sut chuyn ha BOB (%) SS nc thi u ra (mg/L) 20 20 20 20 30 20

60 120

80 160

15

50 180

200 500

80 95

80 95

60 80

80 95

50 85

80 95

80 140

150 300

10 30

40 60

80 160

80 250

Ngun: Wastewater Engineering: treatment, reuse, disposal, 1991 B: c thit b thng kh (nu khng th lu lng np BOD gim xung cn 1/3) acre 0,4047 = ha ft 0,3048 = m lb/acre.d 1,1209 = kg/ha.d

C c hu vc trong m t ao x n c thi (facultative CC PHNG PHP X YM KH M t s d iu v qu trnh hot ng ca h thng y m h dng x n c thi cng nghip

oi hm

COD u vo (mg/L) 1.500 5000

Thi gian u tn n c (h) 2 10

u ng np ch t hu c ( b COD/ft3.d) 0,03 0,15

Hiu su t h COD (%) 75 90

Hm c khuy o Hm UASB

5.000 15.000

4 12

0,25 0,75

75 80

Thi gian tn lu (HRT) ca hn hp np ti u bin thin t 10 60 ngy. Thi gian tn lu ph thuc vo loi nguyn liu np v iu kin mi trng ca hm . HRT Th tch hm = ---------------------------

--Th tch nguyn liu np

i vi hm khng c gi bm gi tr HRT = 1 10 ngy cho ct lc ym kh v 0,5 6 ngy cho loi hm UASB (Brown and Tata, 1985). S d loi hm c gi bm c th chu c lng cht hu c np cao v thi gian lu tn ngn l do mt vi khun trong hm cao do vi khun bm vo cc gi bm trong hm . C c oi hm Ngi ta c th chia cc loi hm theo 3 cch vn hnh chnh

Vn hnh theo m

Trong cch vn hnh ny, hm c np y nguyn liu trong mt ln, cho thm cht mi v y kn li v qu trnh sinh kh s din ra trong mt thi gian di cho ti khi no lng kh sinh ra gim thp ti mt mc no . Sau ton b cc cht thi ca hm c ly ra ch cha li 10 20 % lm cht mi, nguyn liu mi li c np y cho hm v qu trnh c tip tc. Theo kiu vn hnh ny th lng kh sinh ra hng ngy khng n nh, n thng cao vo lc mi np v gim dn n cui chu k .

Vn hnh bn lin tc

Nguyn liu c np vo cho hm 1 hoc 2 ln/ngy v cng mt lng cht thi ca hm s c ly ra ngay cc thi im . Kiu vn hnh ny thch hp khi ta c mt lng cht thi thng xuyn. Th tch ca hm phi ln lm 2 nhim v: phn v cha gas. Theo kiu vn hnh ny th tng th tch gas sn xut c trn mt n v trng lng cht hu c thng cao.

Vn hnh lin tc

cch vn hnh ny vic np nguyn liu v ly cht thi ca hm ra c tin hnh lin tc. Lng nguyn liu np c gi n nh bng cch cho chy trn vo hm hoc dng bm nh lng. Phng php ny thng dng x l cc loi nc thi c hm lng cht rn thp.

Cng nn ni thm rng nu khng c cht thi hm lm cht mi, th phn gia sc cng c th s dng lm cht mi (trong trng hp nguyn liu np khng phi l phn ngi hay phn gia sc). Trong trng hp ny, hm s hot ng n nh sau 20 30 ngy k t lc bt u vn hnh (ph thuc vo nhit , th tch hm , nguyn liu v lng cht mi). C c mu hm

Hm np vm c nh (Trung Quc)

Loi hm ny c phn cha kh c xy dng ngay trn phn phn. Do , th tch ca hm bng tng th tch ca 2 phn ny. Hm c dng bn cu c chn hon ton di t tit kim din tch v n nh nhit . Phn cha kh c t bng nhiu lp va bo m yu cu kn kh. phn trn c mt np y c hn kn bng t st, phn np ny gip cho thao tc lm sch hm khi cc cht rn lng y hm. Loi hm ny rt ph bin Trung Quc, nhng c nhc im l phn cha kh rt kh xy dng v bo m kn kh do hiu sut ca hm thp. Gn y cc nh khoa hc ca c v Thi Lan hp tc trong vic pht trin hm Biogas Thi Lan dng k thut CAD (Computer Aid Design) tnh ton li kt cu ca hm ny v cho ra i mu hm TG - BP (Thai German - Biogas Program). Loi hm ny c Trung Tm Nng Lng Mi, i Hc Cn Th th nghim v pht trin c hiu qu min Nam Vit Nam trong vic x l phn ngi v gia sc.

Hm np tri ni (n )

Loi hm ny rt ph bin n , cn gi l hm kiu KVIC (c thit k bi Khadi and Village Industries Commission). Gm c mt phn hm hnh tr xy bng gch hoc btng li thp v mt chung cha kh tri ni trn mt ca hm . Chung cha kh thng c lm bng thp tm, btng li thp, btng ct tre, cht do hoc si thy tinh. Loi hm ny b nh hng nhiu bi cc nhn t mi trng nh nhit . Np hm d b n mn (trong trng hp lm bng st tm), hoc b lo ha (trong trng hp lm bng cht do). Mt nhc im khc l p sut gas thp do bt tin trong vic thp sng, un nu... khc phc nhc im ny ngi ta thng treo thm vt nng vo np hm .

Mt s loi hm Vit Nam

a) Hm CT1

Vit Nam ngoi vic p dng cc mu hm np vm c nh, np tri ni, TTNLM cn thit k mu hm CT1. Loi hm ny l bin dng ca hm np c nh, hm c dng hnh tr trn, c chung cha kh lm bng xi mng li thp, cc cu kin ca hm c c sn do thi gian thi cng rt ngn xung cn t 2 3 ngy. Loi hm ny c pht trin trn 100 ci khu vc Cn Th v vi chc ci cc tnh thuc BSCL, tui th ca hm trn 10 nm. Hin nay loi hm ny khng cn c a chung na do cc cu kin c sn cng knh gy kh khn tn km trong qu trnh vn chuyn, nguyn liu np phi c thu gom v np bng tay cho hm . Ngoi ra cc Trung Tm Khuyn Nng cn ang pht trin loi ti bng nylon. Loi ny c u im l vn u t thp ph hp vi mc thu nhp ca b con nng dn hin nay. Tui th ca ti ty thuc vo thi gian lo ha ca nguyn liu lm ti. Nhc im ca loi ti l rt d h hng do s ph hoi ca chut, gia sc, gia cm. b) Hm c chung cha kh ring bit Loi hm ny c th ging nh bt k mt kiu no nu trn ch khc l c chung cha kh nm ring, chung cha kh ny c th dng chung cho mt vi hm . u im chnh ca loi hm ny l kh nng cung cp gas n nh (ngay c trng hp theo m) vi mt p sut n nh. Tuy nhin loi hm ny khng c ph bin cc nc ang pht trin.

Cc loi hm c cung cp gi bm cho vi khun hot ng

a) Ct lc ym kh (Young and Mc. Carty, 1969) y l mt ct hnh tr cha , si, hoc mt s loi ht nha nhm cung cp gi bm cho cc vi sinh vt. Cc loi nguyn liu ny c tng din tch b mt cng rng cng thch hp cho vic bm v to mt lp mng vi sinh vt phn hy cht thi. Loi ct lc ym kh ny ch dng x l cc cht thi ha tan hoc nc thi c hm lng vt cht rn thp, v cc cht rn d gy hin tng nght ct lc. b) Hm loi UASB LKi hm ny c thit k bi Lettinga v cc cng s vin vo 1983 Netherlands. Loi hm ny thch hp cho vic x l cc cht thi c hm lng cht hu c cao v thnh phn vt cht rn thp. Hm gm 3 phn chnh: (a)

phn bn c di y hm , (b) mt lp thm bn gia hm, (c) dung dch lng pha trn. Nc thi c np vo hm t y hm, n i xuyn qua lp thm bn ri i ln trn v ra ngoi. Cc cht rn trong nc thi c tch ra bi thit b tch cht kh v cht rn trong hm. Cc cht rn s lng xung lp thm bn do n c thi gian lu tr trong hm cao v hm lng cht rn trong hm tng. Lc hm mi bt u hot ng kh nng lng ca cc cht rn rt thp nhng khi n c tch tr nhiu v to thnh cc ht bn th kh nng lng tng ln v s gp phn gi li cc VSV hot ng. Khong 80 90% qu trnh phn hy din ra thm bn ny. Thm bn ny chim 30% th tch ca hm UASB. S dng biogas Da trn c s nhit tr ca Biogas (4500 6300 Kcal/m3), Hesse (1982) c tnh rng 1m3 Biogas :

chy mt ng c 1 nga trong 2 gi cung cp mt in nng khong 1.25 KWh cung cp nng lng nu n ngy 3 bui cho gia nh 5 ngi thp sng trong vng 6 gi ( sng tng ng n 60 W) chy 1 t lnh 1 m3 trong 1 gi chy mt l m 1 m3 trong na gi

Nh vy 1m3 Biogas tng ng vi 0,4 kg du diesel, 0,6 kg du ha, 0,8 kg than.

S dng Biogas chy ng c Diesel: trong cc h thng x l kt hp ym kh v hiu kh ngi ta cn s dng in nng chy my bm, my nn kh... do Biogas c s dng chy ng c diesel, chng ta nn loi b CO2 v H2S t hiu qu cao v gim n mn my do H2S.

Cch lc CO2

V CO2 c th ha tan trong nc do vic sc Biogas qua nc c coi l phng php n gin nht loi CO2. Ngoi ra CO2 cn c th b hp thu bi nhng dung dch kim, do ta cng c th dng dung dch NaOH, Ca(OH) 2 and KOH loi CO2. Cc phng trnh phn ng nh sau: 2NaOH + CO2 ---> Na2CO3 + H2O (q)

Na2CO3 + CO2 + H2O ---> 2NaHCO3 Ca(OH)2 + CO2 ----> CaCO3 + H2O 1 kg vi nung ha tan trong 1m3 nc loi 300 L CO2.

Kh n ng ha tan ca CO2 trong n c ( g CO2 trong 100 kg H2O) p sut atm 1 10 50 100 200 kg/cm2 1,03 10,3 51,7 103 207 0 0,40 3,15 7,70 8,00 10 0,25 2,15 6,95 7,20 7,95 Nhit (oC) 20 0,15 1,30 6,000 6,66 7,20 30 0,10 0,90 4,80 6,00 6,55 40 0,10 0,75 3,90 5,40 6,05

(Theo Nonhebel (1972), trch dn bi Chongrak, 1989)

Loi H2S

NaCO3 pt (q) c th dng loi H2S trong Biogas qua phn ng sau: H2S + Na2CO3 ---> NaHS + NaHCO3 Mt cch n gin khc l cho Biogas i qua mt st trn ln vi dm bo. Phn ng loi H2S nh sau: Fe2O3 + 3H2S -----> Fe2S3 + 3H2O Sau khi s dng oxyt st c ti sinh bng cch em Fe2S3 phi nng, ta c: 2Fe2S3 + 3O2 -----> 2Fe2O3 + 3S2.

GII THIU CC C CH TRONG CNH NG C Trong mi trng t nhin, cc qu trnh l , ha v sinh hc din ra khi t, nc, sinh vt v khng kh tc ng qua li vi nhau. Li dng cc qu trnh ny, ngi ta thit k cc h thng t nhin x l nc thi. Cc qu trnh xy ra trong t nhin ging nh cc qu trnh xy ra trong cc h thng nhn to, ngoi ra cn c thm cc qu trnh quang hp, quang oxy ha, hp thu dng cht ca h thc vt. Trong cc h thng t nhin cc qu trnh din ra vn tc "t nhin" v xy ra ng thi trong cng mt h sinh thi, trong khi trong cc h thng nhn to cc qu trnh din ra tun t trong cc b phn ng ring bit. X n c thi bng c nh ng c Gii thiu X l nc thi bng cnh ng lc l vic ti nc thi ln b mt ca mt cnh ng vi lu lng tnh ton t c mt mc x l no thng qua qu trnh l , ha v sinh hc t nhin ca h t - nc - thc vt ca h thng. cc nc ang pht trin, din tch t cn tha thi, gi t cn r do vic x l nc thi bng cnh ng lc c coi nh l mt bin php r tin. X l nc thi bng cnh ng lc ng thi c th t c ba mc tiu:

X l nc thi Ti s dng cc cht dinh dng c trong nc thi sn xut Np li nc cho cc ti nc ngm

So vi cc h thng nhn to th vic x l nc thi bng cnh ng lc cn t nng lng hn. X l nc thi bng cnh ng lc cn nng lng vn chuyn v ti nc thi ln t, trong khi x l nc thi bng cc bin php nhn to cn nng lng vn chuyn, khuy trn, sc kh, bm hon lu nc thi v bn... Do t s dng cc thit b c kh, vic vn hnh v bo qun h thng x l nc thi bng cnh ng lc d dng v t tn km hn. Tuy nhin, vic x l nc thi bng cnh ng lc cng c nhng hn ch nh cn mt din tch t ln, ph thuc vo cu trc t v iu kin kh hu. Ty theo tc di chuyn, ng i ca nc thi trong h thng ngi ta chia cnh ng lc ra lm 3 loi:

Cnh ng lc chm (SR) Cnh ng lc nhanh (RI)

Cnh ng chy trn (OF)

Cc c ch x l nc thi trong cnh ng lc a) Cc c ch l hc: Khi nc thi ngm qua cc l rng ca t, cc cht rn l lng s b gi li do qu trnh lc. dy ca tng t din ra qu trnh lc bin thin theo kch thc ca cc cht rn l lng, cu trc t v vn tc ca nc thi. Lu lng nc thi cng cao, cc ht t cng ln th b dy ca tng t din ra qu trnh lc cng ln. i vi cnh ng lc chm do lu lng nc thi p dng cho h thng thp nn cc cht rn l lng c kch thc ln s b gi li ngay trn b mt t, cc cht rn l lng c kch thc nh v vi khun b gi li vi centimet t mt. Cc cht ha tan trong nc thi c th b pha long do nc ma, cc qu trnh chuyn ha ha hc v sinh hc c th loi b c cc cht ny. Tuy nhin nhng vng kh hn c tc bc hi nc cao, cc cht ny c th b tch t li (v d cc mui khong). Mt iu khc cn ch l nu hm lng cht l lng qu cao n s lp y cc l rng ca t lm gim kh nng thm lc ca t, cng nh lm nght cc h thng ti. Trong trng hp ny ta nn cho cnh ng lc "ngh" mt thi gian cc qu trnh t nhin phn hy cc cht rn l lng tch t ny, phc hi li kh nng thm lc ca t.

b) Cc c ch ha hc: Hp ph v kt ta l hai c ch x l ha hc quan trng nht trong qu trnh. Qu trnh trao i cation chu nh hng bi kh nng trao i cation ca t (CEC), thng kh nng trao i cation ca t bin thin t 2 60meq/100g. Hu ht cc loi t c CEC nm trong khong 10 30. Qu trnh trao i cation quan trng trong vic kh nitogen ca amonium. Phospho c kh bng cch to thnh cc dng khng hoc t ha tan. cc vng kh hn kh trnh khi vic tch t ca cc ion Natri lm ph hy cu trc t v gim kh nng thm lc ca t. nh gi mc nguy hi ca qu trnh ny ngi ta thng dng t l hp ph natri (SAR)

C c oi t v u ng n c thi ng dng cho c c c nh ng c b) Cc c ch ha hc: Hp ph v kt ta l hai c ch x l ha hc quan trng nht trong qu trnh. Qu trnh trao i cation chu nh hng bi kh nng trao i cation ca t (CEC), thng kh nng trao i cation ca t bin thin t 2 60meq/100g. Hu ht cc loi t c CEC nm trong khong 10 30. Qu trnh trao i cation quan trng trong vic kh nitogen ca amonium. Phospho c kh bng cch to thnh cc dng khng hoc t ha tan. cc vng kh hn kh trnh khi vic tch t ca cc ion Natri lm ph hy cu trc t v gim kh nng thm lc ca t. nh gi mc nguy hi ca qu trnh ny ngi ta thng dng t l hp ph natri (SAR) C c oi t v u ng n c thi ng dng cho c c c nh ng c trong o Na, Ca, Mg la nong o cac cation tng ng co trong nc thai c tnh bang meq/L. Khi dung canh ong loc e x ly nc thai cong nghiep can phai co bc tien x ly nham khong che pH cua nc thai trong khoang 6,5 9 e khong lam hai tham thc vat. Neu nc thai co SAR cao phai tm cach loai bo Natri e khong che SAR khong ln hn 8 10. c) C che sinh hoc: Cac qua trnh sinh hoc thng dien ra phan re cua tham thc vat. So lng vi khuan trong dat bien thien t 1 3 t/g at, s a dang cua chung cung giup cho qua trnh phan huy cac chat hu c t nhien hoac nhan tao. S hien dien hay khong cua oxy trong khu vc nay cung anh hng rat ln en qua trnh phan huy va san pham cuoi cung cua he thong. Ham lng oxy co trong khu vc nay tuy thuoc vao cau truc (o rong) cua at. Do s phan huy cua cac vi sinh vat at, cac chat nitrogen, phosphorus, sulfur chuyen t dang hu c sang dang vo c va phan ln c ong hoa bi he thc vat. Lu y qua trnh kh nitrat cung co the dien ra neu lu lng nap chat hu c qua cao, at qua mn, thng xuyen ngap nc, mc thuy cap cao, pH at trung tnh hoac kiem nhe, nhiet o am...

Cac mam benh, ky sinh trung b tieu diet do ton tai ben ngoai ky chu mot thi gian dai, canh tranh vi cac vi sinh vat at, bam tren cac bo phan cua tham thc vat sau o b tieu diet bi tia UV trong bc xa mat tri CNH NG C CHM Cnh ng lc chm l h thng x l nc thi thng qua t v h thc vt lu lng nc thi np cho h thng khong vi cm/tun. Cc c ch x l din ra khi nc thi di chuyn trong t v thc vt, mt phn nc thi c th i vo nc ngm, mt phn s dng bi thc vt, mt phn bc hi thng qua qu trnh bc hi nc v h hp ca thc vt. Vic chy trn ra khi h thng c khng ch hon ton nu c thit k chnh xc.

S di chuyn ca n c thi trong c nh ng c chm

Lu lng np cho h thng bin thin t 1,5 10 cm/tun ty theo loi t v thc vt. Trong trng hp cy trng c s dng lm thc phm cho con ngi nn kh trng nc thi trc khi a vo h thng hoc ngng ti nc thi 1 tun trc khi thu hoch bo m an ton cho sn phm. thit k h thng ny ta cn cc cng thc tnh ton sau: Lh + Pp = ET + W + R (7.1) trong Lh: lu lng nc thi np cho h thng (cm/tun) Pp: lng nc ma (cm/tun)

ET: lng hi nc bay hi do qu trnh bc hi nc v h hp ca thc vt (cm/tun) W: lng nc thm qua t (cm/tun) R: lng nc chy trn (cm/tun) (= 0 nu thit k chnh xc)

trong I: kh nng thm lc ca t, mm P": m cui cng ca t, % trng lng P': m ban u ca t, % trng lng S: t trng ca t D: b dy ca lp t m do ti nc thi V d: m ca t trc khi ti nc thi l 19% kh nng thm lc ca t l 1.000 m3/ha t trng ca t l 1,5 b dy ca lp t m do ti nc thi l 90 cm Lng nc mt i do bay hi v h hp ca thc vt l 250mm/thng Xc nh chu k ti nc thi, m ca t sau khi ti nc thi?

Gii: Ta c: I = 1.000m3/10.000m2 = 0,1 m = 100 mm P" = 27,3%

Chu k ti nc thi: = 12 ngay

Nh vy ta c th dng 5 ngy cho vic ti tiu v 7 ngy t ngh qu trnh phn hy cc cht rn l lng xy ra hi phc kh nng ti tiu ca t. Ngoi ra trong qu trnh ti tiu vo ma ma cng nn tnh n lng nc ma trong tun theo phng trnh 7.1. Mc thy cp phi thp hn mt t 0,6 1,0 m trnh vn nhim nc ngm. dc ca cnh ng c trng trt khng ln hn 20%, ca cnh ng khng trng trt v sn i khng ln hn 40%. Kh nng kh BOD5, SS v coliform trong khong 99%. Nit b hp thu bi thm thc vt v nu cc thc vt ny c thu hoch v chuyn i ni khc th hiu sut c th t n 90% CNH NG C NHANH X l nc thi bng cnh ng lc nhanh l vic a nc thi vo cc knh o khu vc t c thm lc cao (mn pha ct, ct) vi mt lu lng np ln. Cc iu kin a l nh thm lc ca t, mc thy cp rt quan trng i vi vic ng dng phng php ny. Nc thi sau khi thm lc qua t c thu li bng cc ng thu nc t ngm trong t hoc cc ging khoan. Mc tiu ca phng php x l ny l:

Np li nc cho cc ti nc ngm, hoc nc mt Ti s dng cc cht dinh dng v tr nc thi li s dng cho cc v ma

Phng php ny gip x l trit cc loi nc thi v ngn chn s xm nhp mn ca nc bin vo cc ti nc ngm. Tuy nhin cc dng m hu c c th chuyn ha thnh m nitrt v i vo nc ngm, nu vt qu tiu chun 10mg/L khi s dng chng lm nc sinh hot s gy bnh methemoglobinenia tr em. nu khu vc x l nm trong tnh trng ym kh H2S s sinh ra lm nc ngm c mi hi. Hiu sut x l SS, BOD5, coliform trong phn ca h thng gn nh trit , hiu sut kh nit khong 50%, phospho khong 70 95%. Cc im cn lu cho qu trnh thit k l lu lng np nc thi 10 250 cm/tun. Thi gian np ko di

0,5 3 ngy sau cho t ngh 1 5 ngy. su ca mc nc ngm t 3 2 m. dc thng nh hn 5%. xc nh kh nng thm lc ca t ngi ta thng khoan cc l ng knh 100 300 cm. y ca l nm ngang mc vi tng t cn cho thit k, y nc, thm lc c xc nh theo hai cch: su ca lp nc rt i trong mt khong thi gian nht nh hay l thi gian cn thit nc trong l rt xung mt mc no . xc nh lng nit b kh i ngi ta dng cng thc:

trong Nt: tng lng nitrogen b kh i mg/L TOC: tng lng carbon hu c trong nc thi ban u mg/L -5 do lng TOC cn li sau khi nc thi thm qua lp t dy 1,5 m cn 5 mg/L /2 do cc thc nghim cho thy cn 2 gcarbon hu c khong ha 1g nit Lu lng np nc thi: Lw = (IR in/h) (1 ft/12 in) (24 h/d) (OD d/yr) (F) trong Lw: lu lng nc thi np hng nm; ft/yr IR: tc thm lc ca t; in/h OD: s ngy vn hnh trong nm; d F: h s thm lc cho tng loi hnh xc nh thm lc F: 10 15% gi tr thm lc nh nht khi th nghim bng knh o F: 4 10% gi tr thm lc khi o dn nc ca t theo chiu ng Din tch cn s dng:

Ghi ch: nn cng thm din tch cho ng i ni b, khu vc tr, khu vc m v d tr m rng trong tng lai.

CNH NG CHY TRN L phng php x l nc thi trong nc thi c cho chy trn ln b mt cnh ng c dc nht nh xuyn qua cc cy trng sau tp trung li trong cc knh thu nc. Mc ch:

X l nc thi n mc ca cc qu trnh x l cp II, cp III Ti s dng cht dinh dng trng cc thm c hoc to cc vnh ai xanh.

Hiu sut x l SS, BOD5 ca h thng t 95 99%, hiu sut kh nit khong 70 90%, phospho khong 50 60%. Cc im cn lu

cho qu trnh thit k:

t t thm nc st hoc st pha ct Lu lng np nc thi th l 10 cm/tun Lu lng np nc thi sau x l cp I l 15 20 cm/tun Lu lng np nc thi sau x l cp II l 25 40 cm/tun.

su ca mc nc ngm khng cn thit. dc khong 2 4%, chiu di ng i ca nc thi khng nh hn 36 m. Thi gian np ko di 6 8 gi sau cho t ngh 16 18 gi, vn hnh 5 6 ngy/tun. Tnh lng BOD5 v TOC b kh theo cng thc:

BOD5:

TOC:

trong o C: BOD5 hoac TOC can at cua nc thai au ra C0: BOD5 hoac TOC cua nc thai au vao

A va A': he so thc nghiem ve kha nang kh BOD5 hoac TOC cua he thong K va k': hang so thc nghiem ve toc o kh BOD5 hoac TOC cua he thong K hoac k' = k/qn k va n: he so thc nghiem q: lu lng nap nc thai cho he thong 0,1 0,37 m3/hr.m (theo chieu doc)

Cac gia tr k va n Loai nc thai k Nc thai sau x ly cap I BOD5 TOC Nc thai sau x ly cap II BOD5 TOC 0,030 0,032 0,402 0,350 0,043 0,038 0,136 0,170 Cac he so n

Cac gia tr A va A' bien oi ln theo q do o e ap dung cac tnh toan nay ngi ta dung bien phap qui chieu t cac o th sau:

T le BOD5 va TOC con lai theo chieu dai ng i cua nc thai tho va nc thai a x ly cap I X NC THI BNG THY SINH THC VT l nc thi bng to To l nhm vi sinh vt c kh nng quang hp, chng c th dng n bo (vi loi c kch thc nh hn mt s vi khun), hoc a bo (nh cc loi rong bin, c chiu di ti vi mt). Cc nh phn loi thc vt da trn cc loi sn phm m to tng hp c v cha trong t bo ca chng, cc loi sc t ca to phn loi chng.

M t s oi to ti u biu

To c tc sinh trng nhanh, chu ng c cc thay i ca mi trng, c kh nng pht trin trong nc thi, c gi tr dinh dng v hm lng protein cao, do ngi ta li dng cc c im ny ca to :

X l nc thi v ti s dng cht dinh dng. Cc hot ng sinh hc trong cc ao nui to ly i cc cht hu c v dinh dng ca nc thi chuyn i thnh cc cht dinh dng trong t bo to qua qu trnh quang hp. Hu ht cc loi nc thi th, nng nghip, phn gia sc u c th c x l bng h thng ao to.

Bin nng lng mt tri sang nng lng trong cc c th sinh vt. To dng nng lng mt tri quang hp to nn ng, tinh bt... Do vic s dng to x l nc thi c coi l mt phng php hu hiu chuyn i nng lng mt tri thnh nng lng ca c th sng. Tiu dit cc mm bnh. Thng qua vic x l nc thi bng cch nui to cc mm bnh c trong nc thi s b tiu dit do cc yu t sau y: 1. S thay i pH trong ngy ca ao to do nh hng ca qu trnh quang hp 2. Cc c t tit ra t t bo to 3. V s tip xc ca cc mm bnh vi bc x mt tri (UV)

Thng thng ngi ta kt hp vic x l nc thi v sn xut v thu hoch to loi b cht hu c trong nc thi. Tuy nhin to rt kh thu hoch (do kch thc rt nh), a s c thnh t bo dy do cc ng vt rt kh tiu ha, thng b nhim bn bi kim loi nng, thuc tr su, cc mm bnh cn li trong nc thi. Cc phn ng din ra trong ao to ch yu l "hot ng cng sinh gia to v vi khun".

S o cua mot ao nuoi tao tham canh

Cc yu t cn thit cho qu trnh x l nc thi bng to Dng cht: Ammonia l ngun m chnh cho to tng hp nn protein ca t bo thng qua qu trnh quang hp. Phospho, Magnesium v Potassium cng l cc dng cht nh hng n s pht trin ca to. T l P, Mg v K trong cc t bo to l 1,5 : 1 : 0,5.

su ca ao to: su ca ao to c la chn trn c s ti u ha kh nng ca ngun sng trong qu trnh tng hp ca to. Theo cc c s l thuyt th su ti a ca ao to khong 4,5 5 inches (12,5cm). Nhng nhng th nghim trn m hnh cho thy su ti u nm trong khong 8 10 inches (20 25cm). Tuy nhin trong thc t sn xut, su ca ao to nn ln hn 20cm (v nm trong

khong 40 50 cm) to thi gian lu tn cht thi trong ao to thch hp v tr hao th tch mt i do cn lng.

Thi gian lu tn ca nc thi trong ao (HRT): thi gian lu tn ca nc thi ti u l thi gian cn thit cc cht dinh dng trong nc thi chuyn i thnh cht dinh dng trong t bo to. Thng th ngi ta chn thi gian lu tn ca nc thi trong cc ao ln hn 1,8 ngy v nh hn 8 ngy.

Lng BOD np cho ao to: lng BOD np cho ao to nh hng n nng sut to v nu lng BOD np qu cao mi trng trong ao to s tr nn ym kh nh hng n qu trnh cng sinh ca to v vi khun. Mt s th nghim Thi Lan cho thy trong iu kin nhit i su ca ao to l 0,35 m, HRT l 1,5 ngy v lng BOD np l 336 kg/(ha/ngy) l ti u cho cc ao to v nng sut to t c l 390 kg /(ha/ngy).

Khuy trn v hon lu: qu trnh khuy trn trong cc ao to rt cn thit nhm ngn khng cho cc t bo to lng xung y v to iu kin cho cc dinh dng tip xc vi to thc y qu trnh quang hp. Trong cc ao to ln khuy trn cn ngn c qu trnh phn tng nhit trong ao to v ym kh y ao to. Nhng vic khuy trn cng to nn bt li v n lm cho cc cn lng ni ln v ngn cn qu trnh khuch tn nh sng vo ao to. Moraine v cc cng s vin (1979) cho rng tc dng chy trong ao to ch nn khong 5 cm/s. Hon lu gip cho ao to gi li c cc t bo vi khun v to cn hot ng; gip cho qu trnh thng thong kh, thc y nhanh cc phn ng trong ao to.

Thu hoch to: to c th c thu hoch bng li hoc giy lc, thu hoch bng cch to bng cn hoc tch ni, thu hoch sinh hc bng cc loi c n thc vt v ng vt khng xng sng n to.

l nc thi bng thy sinh thc vt c kch thc ln

Thy sinh thc vt l cc loi thc vt sinh trng trong mi trng nc, n c th gy nn mt s bt li cho con ngi do vic pht trin nhanh v phn b rng ca chng. Tuy nhin li dng chng x l nc thi, lm phn compost, thc n cho ngi, gia sc c th lm gim thiu cc bt li gy ra bi chng m cn thu thm c li nhun.

Cc loi thy sinh thc vt chnh Thy thc vt sng chm: loi thy thc vt ny pht trin di mt nc v ch pht trin c cc ngun nc c nh sng. Chng gy nn cc tc hi nh lm tng c ca ngun nc, ngn cn s khuych tn ca nh sng vo nc. Do cc loi thy sinh thc vt ny khng hiu qu trong vic lm sch cc cht thi.

Thy thc vt sng tri ni: r ca loi thc vt ny khng bm vo t m l lng trn mt nc, thn v l ca n pht trin trn mt nc. N tri ni trn mt nc theo gi v dng nc. R ca chng to iu kin cho vi khun bm vo phn hy cc cht thi.

Thy thc vt sng ni: loi thy thc vt ny c r bm vo t nhng thn v l pht trin trn mt nc. Loi ny thng sng nhng ni c ch thy triu n nh.

Mot so thuy sinh thc vat tieu bieu oi Thu sinh thc vt sng chm T n thng thng Hydrilla Water milfoil T n hoa hc Hydrilla verticillata Myriophyllum spicatum

Blyxa Thu sinh thc vt sng tri ni tri ni Lc bnh Bo tm Bo tai tng Salvinia Thu sinh thc vt sng ni Cattails Bulrush Sy

Blyxa aubertii Eichhornia crassipes Wolfia arrhiga Pistia stratiotes Salvinia spp Typha spp Scirpus spp Phragmites communis

Nhim v ca thu sinh thc vt trong c c h thng x Phn c th R v/hoc thn Nhim v L gi bm cho vi khun pht trin Lc v hp thu cht rn Thn v /hoc l mt nc hoc pha trn mt nc nHp thu nh mt tri do ngn cn s pht trin ca to lm gim nh hng ca gi ln b mt x l

Lm gim s trao i gia nc v kh quyn Chuyn oxy t l xung r

M t s thu sinh thc vt ti u biu M t s gi tr tham ho thi t Thng s ao c Bnh x n c thi Ch t ng n c thi sau x

S iu thi t

Nc thi th

Thi gian lu tn nc Lu lng np nc thi su ti a Din tch mt n v ao Lu lng np cht hu c T l di : rng ca ao

> 50 ngy 200 m3/(ha.day) < 1,5 m 0,4 ha < 30kg BOD5/(ha.day) >3:1

BOD5 < 30mg/L TSS < 30 mg/L

Nc thi qua x l cp I

Thi gian lu tn nc Lu lng np nc thi su ti a Din tch mt n v ao Lu lng np cht hu c T l di : rng ca ao

> 6 ngy 800 m3/(ha.day) 0,91 m 0,4 ha < 50kg BOD5/(ha.day) >3:1

BOD5 < 10mg/L TSS < 10 mg/L TP < 5 mg/L TN < 5 mg/L

O'Brien (1981) trch dn bi Chongrak Polprasert (1989) X BN

Vic x l bn to ra t cc qu trnh x l l , ha, sinh hc cng rt cn thit hon thin mt h thng x l . i vi bn c cha kim loi nng kt ta trong qu trnh x l ha hc ngi ta thng c c, sau xi mng ha v thi i cc khu vc qui nh. i vi cc loi bn t b lng s cp, th cp ngi ta c th x l bng hm Biogas hoc qu trnh phn compost, sn phi bn... ty iu kin cho php.

San phi bun 2. X NC THI - ng ngh sn xu t m vi sinh Lng c ng Lm v ang dng loi vt liu thn thin vi mi trng m li c sn trong a phng (ct tre ti) sn xut ra loi m vi sinh dng cho ngnh x l nc thi bo v mi trng. y l loi vt liu khng gy nhim trong qu trnh sn xut, c bn cao khi ngm trong nc, c kh nng cho vi sinh lm t cao hn nhiu ln so vi m vi sinh hin ang c s dng trn th gii. loi vt liu ny khi cn tiu hy ch cn phng php tht n gin - t thu cng. cung cp cho ngnh x l nc thi mi nm nc ta c khong 1.200.000 m3 m vi sinh trong tng lai, ngi ta phi u t cc nh my sn xut nha vi vn u t ht hng trm t ng 3.