BÀI TIỂU LUẬN XỬ LÝ NƯỚC THẢI CN GIẤY - NHÓM 4

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<p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>GII THIU CHUNGGiy l mt sn phm x si xenlulose c dng tm, trong si v cc phn si c lin kt vi nhau to mng khng gian 3 chiu. Giy l sn phm c vai tr quan trng trong mi lnh vc hot ng ca con ngi. Cng vi s pht trin ca cc ngnh cng nghip, dch v khc, nhu cu v cc sn phm giy ngy cng tng. Giy c sn xut t bt giy, bt giy li c sn xut ra t nguyn liu ban u l cc loi thc vt nh g, tre na, cc loi cy thn thoBt giy c thnh phn ha hc ch yu l xenluloza. cc loi thc vt ni chung c thnh phn chnh nh sau: Xenluloza, hemoxenluloza, lignin v cc hp cht khc. Cng nghip sn xut giy chim v tr kh quan trng trong nn kinh t nc ta. p ng nhu cu s dng giy ngy cng tng, cc nh my, x nghip sn xut giy xut hin nhiu trong nhng nm gn y nht l cc tnh v thnh ph ln. Vi thit b cng ngh sn xut hin i em la hiu qu kinh t cho ch u t, song cng nh cc ngnh cng nghip khc bn cnh li nhun em li trc mt th vn nhim mi trng t ngnh cng nghip ny ang lm au u cc nh u t cng nh ton x hi. Trong cc dng thi th nc thi t ngnh cng nghip ny gy ra nhiu vn nhim ng quan tm cc nc pht trin, cc nc tin tin th cc nh my lm vic vi dy chuyn khp kn c thm cc khu thu hi ti s dng v x l cht thi. Dch kim en sau nu c thu hi a i c c, t, xt ho ti s dng ho cht; nc trng xeo, nc ra li v chn cng c lng, tuyn ni tn dng bt v nc trong, gim thiu cc cht thi ra mi trng. Cn Vit Nam a s cc nh my u khng c cc h thng thu hi c c v t dch en, m thi trc tip ra mi trng hoc mi ch c cng ngh x l s b, iu ny gy mt vn khng nh i vi mi trng. Mt iu cp thit t ra y l phi tm c cng ngh x l, ph hp, ng b, ton din m chi ph x l li khng qu cao i vi cc nh my sn xut.</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>1</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>I.</p> <p>S cng ngh sn xut v cc ngun thi ca qu trnh sn xut giyx l nc sng (khng x l phn) nc sng ( x l phn) NaOH Cl2 NaClO ph gia (Al2(SO4)3 Ca(OH)2 giy nu ra sng ty xeo</p> <p>un nng (NaOH, Na2S)</p> <p>Nguyn liu th</p> <p>x l nguyn liu</p> <p>- BOD - V cy - Ct sn dch trng (NaOH, Na2S)Ca(OH)2</p> <p>- BOD - Dch en long (NaOH, Na2S). - H.cht cha S.</p> <p>- BOD - Hp cht cha Clo. - S si. NaCl</p> <p>- BOD - S si. - Cht ph gia.</p> <p>dch ngng</p> <p>chng</p> <p>dch en c</p> <p>Xt hoH2O</p> <p>C thu hi</p> <p>sn xut ho cht</p> <p>dch xanh</p> <p>Dch (Na2CO3, Na2S, Na2O)</p> <p>NaOH Cl2 NaClO HCl</p> <p>S cng ngh sn xut v cc ngun thi Cng ngh sn xut giy l mt trong nhng cng ngh s dng nhiu nc. Ty theo tng cng ngh v sn phm m lng nc cn thit sn xut 1 tn giy giao ng t 200 n 500m3 nc. Nc c dng trong cc cng on ra nguyn liu, nu, ty, xeo giy v sn xut hi nc. Nh vy trong qu trnh sn xut giy, hu nh tt c lng nc ua vo s dng s l lng nc thi ra, c 2 ngun sn sinh ra nc thi l: qu trnh xeo giy v trong qu trnh lm vic Nhng yu t gy nhim chnh l: - pH cao do kim d l nguyn nhn chnh. - Thng s cm quan ( mu en, mi, bt) ch yu l do dn xut ca ligin gy ra l chnh. Cn l lng (do bt giy v cc cht n nh cao lin gy ra).</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>2</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>- COD &amp; BOD do cc cht hu c ha tan gy ra l chnh, cc cht hu c y l ligin v cc dn xut ca ligin, cc loi ng cao phn t v mt lng nh cc hp cht c ngun gc sinh hc khc, trong trng hp dng Clo ty trng th nc thi c thm dn xut hu c c cha Clo. II. Thnh phn, tnh cht ca nc thi sn xut giy. 1. Thnh phn, tnh cht. Nc thi ca cc nh my sn xut giy thng c pH trung bnh 9-11, hm lng BOD5 , COD, SS cao gp nhiu ln so vi tiu chun cho php. c bit nc c cha c kim loi nng, lignin (dch en), phm mu, xt, cc cht a vng thm clo ha l nhng hp cht c c tnh sinh thi cao v c nguy c gy ung th, rt kh phn hy trong mi trng. Cc ngun gy nhim trong qu trnh sn xut: - Dng thi ra nguyn liu bao gm cht hu c ha tan, t , thuc bo v thc vt, v cy - Dng thi ca qu trnh nu v ra sau nu cha phn ln cc cht hu c ha tan, cc cht nu v mt phn x si. Dng thi c mu ti nn thng c gi l dch en. Dch en c nng cht kh khong 25 n 35%, t l gia cht hu c c th thu hi ti s dng v v c 70:30. - Thnh phn hu c ch yu l trong dch en lignin ha tan v dch kim. Ngoi ra, l nhng sn phm phn hy hydratcacbon, axit hu c. Thnh phn hu c bao gm nhng cht nu, mt phn nh l NaOH, Na2S, Na2SO4, Na2CO3, cn phn nhiu l kim natrisunfat lin kt vi cc cht hu c trong kim. - Dng thi t cng on ty ca cc nh my sn xut bt giy bng phng php ha hc v bn ha cha cc cht hu c, lignin ha tan v hp cht to thnh ca nhng cht vi cht ty dng c hi. Dng ny c mu, gi tr BOD5 v COD cao. - Dng thi t qu trnh nghin bt v xeo giy ch yu cha x si mn, bt giy dng l lng v cc cht ph gia nh nha thng, phm mu, cao lanh. - Dng thi t cc khu ra thit b, ra sn, dng chy trn c hm lng cc cht l lng v cc cht ri vi. - Nc ngng ca qu trnh c c trong h thng x l thu hi ha cht t dch en. Mc nhim ca nc ngng ph thuc vo loi g, cng ngh sn xut. - Nc thi sinh hot. 2. Tc hi n mi trng - Cht huyn ph: l nhng ht cht rn khng chm trong nc, bao gm cht v c, ct, bi qung hoc nhng cht hu c nh du, cn hu c. Nhiu vt huyn ph x xung ngun nc dn dn s hnh thnh bi si v to ra qu trnh ln men, t tiu hao lng oxi ha tan trong nc, tc ng n s sng ca cc sinh vt trong nc, ph lp khng gian sinh tn, gy cn tr cc hot ng binh thng</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>3</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>- Vt ha hp d sinh ha phn gii: l nhng thnh phn nguyn liu vi s lng tng ng tan trong qu trnh to bt xeo giy d sinh ha phn gii, bao gm cc vt c lng ph t thp (cht bn si, metanol, axit, ccs loi ng) Nhng cht ny d b oxi ha, do cng tiu hao oxy ha tan trong nc, gy tc hi n sinh vt. - Vt ha hp kh sinh ha phn gii: bt ngun ch yu t cht ng phn t ln v ligin trong nguyn liu si. Nhng cht ny thng c mu, do nh hng ti s chiu ri ca nh sng vo ngun nc. Nhng vt cht ny cng c th gy bin d trong c th sinh vt nu b hp thu. - Cc vt cht c c: trong nc thi ca cng nghip giy c rt nhiu cht c i vi sinh vt nh colophan v axit bo khng bo ha trong dch en, dch thi ca n ty trng, dch thi on rt xt. - Dng nc thi ca ngnh cng nghip giy c th lm mt s cn bng sinh thi trong mi trng nc. III. Phng php x l nc thi ca nh my giy 1. X l nc thi ngay ti cng on u (cng on to bt giy) Trong cng on nu thu dc loi dch nu mu en, rt giu ligin(loi hp cht hu c t thc vt rt kh phn hy v cc ha cht nu. gim thiu nng nhim trong dch en ta nn s dng mt s bin php sau: - Tch dch en m c ban u t li gn bt giy v tun hon dng li ni nu s gim c lng kim trong dch thi - Thu hi ha cht t dch en bng cng ngh c c-t-xt ha s gim ti nhim COD 85% Thu hi kim t dch en ca phng php nu sunfat nh sau: + C c. + t dch c c t0 5000C cht hu c chy hon ton, phn cn li l thnh phn v c ca kim en s to tro hoc cn noings chy cn gi l kim . + Xt ha kim bng dung dch kim long v s vi. Sau tch bn vi, dung dch trng gm NaOH, Na2S, Na2CO3, Na2SO4 c thu h v tun hon li cho cng on nu. Ta c th thay ha cht ty trng l Cl2 bng H2O2 v O3 v dng Cl2 c th sinh ra hp cht AXO l hp cht halogen hu c c nguy c gy c tnh tch ly cho c th ngi v cng c kin cho rng l tin t gy ung th.</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>4</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>2. X l nc thi giy ca nh my giy (giai on to giy). Nh chng ta bit, nc thi ca nh my giy ni chung cha nhiu x si xenlulozo, nhiu cht rn l lng dng bt, nhiu cht hu c ha tan dng kh v d phn hy sinh hc cng vi cc ha cht dng ty v hp cht hu c ca chng. i vi nc thi ny chng ta s s dng phng php lng, keo t v sinh hc. a. Phng php lng Phng php lng nhm tch cc cht rn dng bt hay dng x si, trc ht nc thi t cng on nghin v xeo giy. Vi mc ch thu hi li x si, bt giy, ngi ta thng dng thit b lng hnh phu. Trong qu trnh lng cn phi tnh ton thi gian lu thch hp v vi thi gian lu di d c hin tng phn hu k kh khi bn lng khng c ly ra thng xuyn. nc thi loi ny lng c tt v to iu kin cc ht lin kt vi nhau to thnh bng cn d lng, ngi ta thng tnh ton vi ti trng b mt t 1 n 2m3/m2.h (lu lng dng thi tnh cho 1 n v b mt b lng trong n v thi gian). gim thi gian lu trong b lng, nng cao hiu sut lng c th thi kh nn (p sut t 4 n 6 bar) vo b lng. Loi b lng - tuyn ni ny thng c ti lng b mt 5 - 10m3/m2.h.s b. Phng php keo t Phng php keo t ha hc nhm lm keo lng cc ht rn l lng, mt phn cht hu c ha tan, hp cht phospho, mt s cht c v kh mu. - c trc v sau cng trnh x l sinh hc. - Cht keo t thng s dng l phn st, phn nhm v vi. C th dng cht tr keo t l cc cht polymer tng tc lng (phn st dng pH thch hp t 5 11, phn nhm pH thch hp t 57, vi pH 11).</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>5</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>c. Phng php sinh hc. c im ca nc thi giy thng c t l BOD : COD 0,55 v hm lng COD 1000 mg/l.Do vy trong x l c bn (bc II) bng phng php sinh hc thng c hai cng on: Cng on x l k kh (metan ho) t trc. Cng on x l hiu kh t sau trong quy trnh cng ngh .</p> <p>Trong nc thi giy thng giu hidrocacbon ha tan, nhng ngho Nito v phospho dinh dng i vi vi sinh vt. Khi x l sinh hc cn ch cn bng dinh dng cho vi sinh vt pht trin. Cn bng theo t l BOD5:N:P = 100:5:1 vi qu trnh hiu kh l 100: 3: 0,5 vi qu trnh k kh .</p> <p>C th, ta c cc phng n x l nc thi nh my giy nh sau: Ghi ch: : ng nc thi : ng bn cn : ng cp kh : ng ct t b lng ct</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>6</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>Phng n 1:</p> <p> Thuyt minh s : Nc thi sau sn xut c a qua song chn rc gi li cc tp cht th sau nc tip tc c a sang b iu ha nhm iu ha lu lung v nng , nc thi a qua b phn ng ( c trn ha cht) hnh thnh bng cn sau a nc sang b lng 1 v tip tc a sang b lc biofor (k kh- qu trnh vi sinh dnh bm) nhm lm gim lng BOD, khng gy qa ti trong b hiu kh, ti b hiu kh c h thng thi kh cung cp oxi cho b hiu qu ca qu trnh xy ra hon ton, nc tip tc qua b oxi ha bc cao bng ozone n thit b cht xc tc (my pht ozone) n b lc p lc sau kh trng bng clo v nc c x ra ngun tip nhn loi A. u im: - Qua nhiu cng on lc v kh trng bng ozone nn ngun nc m bo cht lng. - B phn ng c lp cn l lng c hiu qu cao, cu to n gin, khng cn my mc c kh, khng tn chiu cao xy dng. - Chim mt din tch kh nh trong xy dng bi s lng cng trnh t. Nhc im: - B phn ng c lp cn l lng thng khi ng chm, lp cn l lng c hnh thnh v lm vic c hiu qu ch sau 3-4 tun. - B lng ng khng p ng c cng sut ln trong x l. - Chi ph vn hnh cao.</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>7</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>Phng n 2:</p> <p> Thuyt minh s : Nc thi t 2 cng on xeo giy v sn xut giy c a qua song chn rc nhm gi li nhng tp cht th sau c a qua lng ct ngang lng cc tp cht v c m bo cho cc qa trnh x l sau, ct t b lng c dn n sn phi ct lm ro nc v em i chn lp hoc tri ng. Nc tip tc a sang b iu ha nhm n nh lu lng v nng , t b iu ha nc c bm trc tip sang b phn ng c trn ha cht hnh thnh bng cn v nng PH ca nc sau a nc sang b lng 1 loi b cc bng cn sinh ra trong qu trnh keo t. y ta thu hi bt cn mt phn bn c a sang b cha bn cn nc a sang b arotank (qu trnh bn hot tnh vi sinh vt l lng) c qu trnh thi kh sau tip tc c a sang b lng 2 (lng ly tm) sau qua lc nhanh v tip tc qua kh trng (c thi kh) bng clo v x ra ngun tip nhn. Mt phn bn hot tnh (sinh vt l lng) t b lng 2 c dn tr li arotank tip tc tham gia qu trnh x l ( bn hot tnh tun hon), phn cn li (bn hot tnh d) c dn n b ch bn ri n b nn v p bn nhm lm gim m v th tich</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>8</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>sau em chn lp hoc dung lm phn bn, nc tch bn t b nn bun v cng on p bn s c dn li b arotank tip tc x l. o u im: Hiu qu x l cao B phn ng c lp cn l lng c hiu qu cao, cu to n gin, khng cn my mc c kh S dng 2 b lng ngang thun li cho qu trnh qun l v v sinh vo ma ma. o Nhc im: Phc tp ha dy chuyn cng ngh trong x l B phn ng c lp cn l lng thng khi ng chm, lp cn l lng c hnh thnh v lm vic c hiu qu ch sau 3-4 tun. Tn nhiu chi ph xy dng cng nh vn hnh</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>9</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>Phng n 3:</p> <p> Thuyt minh s : Nc t thi cng on sn xut giy c a qua h thu nhm iu chnh pH thch hp v nc t cng on xeo giy c a qua song chn rc nhm gi li nhng tp cht th (ch yu l rc) c trong nc thi. Sau nc c a qua b lng ct lng cc tp cht v c m bo cho cc qa trnh x l sau, ct t b lng c dn n sn phi ct lm ro nc v em i chn lp hoc tri ng; Nc tip tc a sang b iu ha nhm n nh lu lng v nng , t b iu ha nc c bm trc tip sang b trn ha cht (trn phn) nhm keo t gim lng cht rn l lng sau a nc sang b lng 1 loi b cc cn sinh ra trong qu trnh trn ha cht. y ta thu hi bt cn mt phn bn c a sang b cha bn cn nc a sang b arotank (qu trnh bn hot tnh vi sinh vt l lng) c qu trnh thi kh sau tip tc c a sang b lng 2 (lng ly tm) qua kh trng (c thi kh) bng clo v x ra ngun tip nhn. Mt phn bn hot tnh (sinh vt l lng) t b lng 2 c dn tr li arotank tip tc tham gia qu trnh x l ( bn hot tnh tun hon), phn cn li (bn hot tnh d) c dn n b</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>10</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>ch bn ri n b nn v p bn nhm lm gim m v th tich sau em chn lp hoc dung lm phn bn, nc tch bn t b nn bun v cng on p bn s c dn li b aerotank tip tc x l. u im: - Gim lng ha cht ngay ban u (nc c a vo h thu iu chnh PH). - Dy chuyn cng ngh ny khng cn c b phn ng trc b trn ha cht. - Hiu qu x l t tiu chun loi B. Nhc im: - Xy dng v qun l kh tn km. - i hi ngi qun l c chuyn mn cao. Phng n 4: a. X l s b nc thi t cng on xeo giy:</p> <p>- Nc thi t cng on xeo giy c tch ring a qua h thng x l s b. - Nc thi chy qua SCR (song chn rc) n b tip nhn. SCR c nhim v gi li cc tp cht kch thc ln. - Nc thi tip tc c bm qua b iu ha iu ha lulng v nng . T y nc thi c bm qua b lng lng cn (ch yu l bt giy). - Sau nc thi c a n h thng x l chung. b. X l s b nc thi t cng on sn xut bt giy:</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>11</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>- Nc thi t cng on sn xut bt giy c tch ring a qua h thng x l s b. - Nc thi chy qua SCR (song chn rc) n b tip nhn. SCR c nhim v gi li cc tp cht kch thc ln. - Nc thi tip tc c bm qua b iu ha iu ha lu lng v nng . T y nc thi c bm qua b trn c b sung NaOH v phn. - Nc thi c cho qua b keo t kt hp vi b lng nhm mc ch to phn ng keo t v lng cn (ch yu l bt giy). - Sau nc thi c a n h thng x l chung. c. H thng x l chung sau khi ha trn hai ngun nc thi qua x l s b:</p> <p>- Sau khi qua mt s bc x l s b nc thi t c hai cng on sn xut c ha trn vi nhau v c iu chnh v khong pH thch hp cho hot ng ca vi sinh vt (pH = 6,5 7,5) ti b trung ha.</p> <p>SVTH: Nhm 4 - Lp: 09CQM</p> <p>12</p> <p>Tm hiu qui trnh x l nc thi cng nghip giy</p> <p>GVHD: Nguyn Th Hng</p> <p>- Nc thi tip tc c cho qua b lc sinh hc hiu kh nhm x l BOD5, COD, mi hi trong nc thi, - Sau khi x l b lc sinh hc hiu kh, nc thi tip tc chy sang b lng 2 loi b bn hot tnh. Lng bn ny c rt khi b lng bng h thng bm bn v tun hon v b lc sinh hc duy tr mt ca vi sinh vt, bn d c dn v b nn bn. - Nc thi b lng 2 tip tc chy qua b kh trng nhm tiu dit vi trng v mm bnh. Sau khi ra khi b kh trng nc thi s t tiu chun QCVN 12:2008 loi A, B ri thi ra ngun tip nhn. 3. Cc bin php hn ch lng nc thi ca ngnh cng nghip giy. a. Cc bin php lm gim lng nc thi: - Bo qun v lm sch nguyn liu u vo bng phng php kh s gim c lng nc ra. - Dng sng phun tia ra my mc, thit b, sn s gim c lng nc ng k so vi ra bng vi. - Thay i cng ngh tch dch en ra khi bt thit b hnh trng thng thng bng p vt thi, p hai dy hay lc chn khng gim th tch dng thi. - Bo ton hi v nc, trnh tht thot hi, chy trn nc. - Phn lun...</p>