chuyn : Cng ngh x l nc thi

Kha Lun Tt Nghip

TRNG I HC NNG LM TP H CH MINHKhoa Mi trng v Ti nguyn

BO CO CHUYN CNG NGH X L NC THI

B mn: Qun lmi trng v pht trin bn vngGio vin: Ts. Nguyn Huy VNhm thc hin: Nhm nc thiThnh vin nhm: MSSV:1. Nguyn Hong Phc 111271662. V Quang Nam 111271423. Trnh V Nam 111271414. To Tin t 111270765. Lu Minh Tun 111271486. L Quang Thnh 111273157. H Tn Phanh111270268. Trn Nht Tun 111273259. Hunh Vit Tin 1112732010. Phm Ngc Tun 11127326

LI M U

Trong sut thi gian va hc qua, chng em c cc thy c trong khoa mi trng tn tnh ch dy, truyn t nhng kin thc qu bu, bi bo co ny l dp chng em tng hp li nhng kin thc hc, gip chng em trang b c hnh trang k lng t tin bc vo cng vic mai sau.Xin chn thnh cm n cc thy c trong khoa Mi trng v ti nguyn ging dy, ch dn, to iu kin thun li cho chng em trong sut thi gian va quaVi kin thc v kinh nghim thc t cn hn ch nn trong bi bo co ny chc chn chng em cn nhiu thiu st, em rt mong nhn c s gp ca cc thy c v bn b nhm rt ra nhng kinh nghim cho cng vic sp ti.

T VN

Trong qu trnh pht tin khng ngng ca x hi, loi ngi t c nhiu thnh t to ln trong cc lnh vc kinh t, x hi vi mt trnh khoa hc k thut hin i, nhng dng thi cng gy ra nhiu hu qu nghim trng cho mi trng, c bit l mi trng nc.Cng vi vic bo v v cung cp ngun nc sch th vic thi v x l nc b nhim trc khi vo ngun tip nhn l vn tt yu. Vit Nam mi ngy c hng triu m3 nc thi sinh hot c a vo mi trng do s pht trin ca th ha v dn s ngy cng gia tng. Nc thi sinh hot x thi trc tip ra ngun tip nhn s nh hng trc tip n ngun nc mt gy nn cc tc ng tiu cc n mi trng v sc khe con ngi. pht trin m khng lm suy thoi mi trng th vic u t xy dng h thng x l nc ph hp l vic lm cn thit. T vic cn phi thit k nhng h thng x l nc thi t hiu qu cao, hm nay nhm chng em lm bi bo co c chuyn Cng ngh x l nc thi vi mc ch cng c li kin thc cho bn thn, ng thi chia s kin thc vi cc bn sinh vin trong mn hc.

chuyn : Cng ngh x l nc thi

27

CHNG I: NGUN GC V TNH CHT CA NC THI

1. Ngun gc pht sinh:1.1. Nc thi sinh hot:Nc thi sinh hot l nc c dng cho cc mc ch n ung, sinh hot, tm ra, v sinh nh ca,... ca cc khu dn c, cng trnh cng cng, c s dch v,...Nh vy, nc thi sinh hot c hnh thnh trong qu trnh sinh hot ca con ngi. Mt s cc hot ng dch v hoc cng cng nh bnh vin, trng hc, bp n,..cng to ra cc loi nc thi c thnh phn v tnh cht tng t nh nc thi sinh hot.Lng nc thi sinh hot ti cc c s dch v, cng trnh cng cng ph thuc vo loi cng trnh, chc nng, s lng ngi.Lng nc thi t cc c s thng mi v dch v cng c th c chn t 15- 25% tng lng nc thi ca ton thnh ph.c trng nc thi sinh hot l: hm lng cht hu c cao (55-65% tng lng cht bn), cha nhiu vi sinh vt c c vi sinh vt gy bnh, vi khun phn hy cht hu c cn thit cho cc qu trnh chuyn ha cht bn trong nc thi.Nc thi sinh hot giu cht hu c, cht dinh dng, l ngun gc cc loi vi khun (c vi khun gy bnh) pht trin l mt trong nhng ngun gy nhim chnh i vi mi trng nc.Nc thi sinh hot c thnh phn ging nhau cc th nhng khc v hm lng, phng php x l ging nhau v x l sinh hc c u tin la chn.Lu lng NT khng iu ha, ph thuc vo thi im trong ngy (Vd: lng ngi trong khu th,...). S lng ngi cng ng ch thi cng iu ha

1.2. Nc thi cng nghip:Trong cc x nghip cng nghip thng to thnh 3 loi NT: Nc c s dng nh nguyn liu sn xut, gii nhit, lm sch bi v khi thi,... Nc c s dng v sinh cng nghip, nhu cu tm ra, n ca ca cng nhn,... Nc ma chy trnNhu cu v cp nc v lng nc thi sn xut ph thuc vo: loi hnh, cng ngh sn xut, loi v thnh phn nguyn vt liu, cng sut nh my,...Cng ngh sn xut nh ln n lng nc tiu th, lng nc thi to thnh, ch x thi v thnh phn tnh cht nc thi. p dng cng ngh tin tin v trang thit b cng hin i, lng nc s dng s gim rt nhiu.

Ngnh cng nghipn v tnhNhu cu cp ncLng NT

Sn xut biaL.nc/ l.bia10-206-12

Cng nghip ngm3 nc/tn ng30-6010-50

Cng nghip giym3 nc/tn giy300-550250-450

Dt nhumm3 nc/tn vi400-600380-580

Nc thi sn xut khng bn: ch yu to ra khi lm ngui thit b, gii nhit trong cc trm lm lnh, ngng t hi nc,...Nc thi sn xut bn: c th cha nhiu loi tp cht vi nng khc nhau (v c, hu c, hoc hn hp). Thnh phn, tnh cht nc thi rt a dng v phc tp. Mt s Nc thi cha cc chtc hi nh kim loi nng (Vd: nc thi xi m), cha nhiu vi khun gy bnh,Nc thi cng nghip ph thuc vo qu trnh sn xut, quy trnh cng ngh. x l cng nghip kh khn hn, mc nhim phc tp hn so vi nc thi sinh hot.Tnh ton lng nc thi ti a: da trn cng sut ca nh my v h thng x l nc thi s khng b qu ti.Nc thi sn xut cha nhiu cht bn khc nhau v c s lng ln thnh phn do khng th c tiu chun v cc ch tiu, thnh phn ha l cho mt loi nc thi no c.2. Nhng c im,tnh cht c trng ca nc thi :Nc thi sinh hot:nc thi c ngun gc pht sinh t cc h gia nh, cng trnh cng cng v khu cng s, c nng cc cht hu c rt cao.Nc thi cng nghip:Tnh cht ca nc thi cng nghip rt a dng do thnh phn v nng cc cht nhim rt khc nhau. Nc thi t cc loi hnh cng nghip nh ha du, ch bin thc phm, bia ru v ha cht thng c hm lng cc hp cht hu c ln, ch s BOD, cht rn l lng v cht rn ha tan cao, PH, mi v cc hp cht sunfua thng hay bin i. nc thi ca cc nh my ha cht thng cha nhiu cc ha cht c hi, c hi i vi cc vi sinh vt trong nc, ngay c khi cc loi cht c ny tn ti vi nng nh trong nc.Mt s ch tiu c trng ca nc thi:2.1. Tng cht rn (TS)Tng cc cht rn c th chia ra lm hai thnh phn: Cht rn l lng (c th lc c, TSS) v cht rn ha tan (khng lc c, TDS).Tng cc cht rn (Total solid, TS) trong nc thi l phn cn li sau khi cho nc thi bay hi hon ton nhit t 103 - 105oC. Cc cht bay hi nhit ny khng c coi l cht rn. Tng cc cht rn c biu th bng n v mg/L. Trong nc thi sinh hot c khong 40 - 65% cht rn nm trng thi l lng.2.2. MiVic xc nh mi ca nc thi ngy cng tr nn quan trng. Mi ca nc thi cn mi thng khng gy ra cc cm gic kh chu, nhng mt lot cc hp cht gy mi kh chu s ta ra khi nc thi b phn hy sinh hc di cc iu kin ym kh. Hp cht gy mi c trng nht l hydrosulfua (H2S - mi trng thi). Hp cht khc, chng hn nh: Indol, skatol, cadaverin... c to di cc iu kin ym kh c th gy ra nhng mi kh chu hn H2S.2.3. mu mu ca nc thi l do cht mn, cc cht ha tan, cht dng keo hoc do thc vt thi ra, s c mt ca mt s ion kim loi (Fe, Mn), to, than bn... N c th lm cn tr kh nng khuch tn ca nh sng vo ngun nc gy nh hng n kh nng quang hp ca h thy sinh thc vt. mu cn lm mt v m quan ca ngun nc nn rt d b s phn ng ca cng ng ln cn.2.4. c c ca nc thi l do cc cht l lng v cc cht dng keo cha trong nc thi to nn. n v o c thng dng NTU2.5. Nhit Nhit ca nc thi thng cao hn so vi nhit ca nc cp do vic x ra cc dng nc nng hoc m t cc hot ng sinh hot, thng mi... v nhit ca nc thi thng thp hn khng kh. Nhit ca nc thi l mt trong nhng thng s quan trng bi v phn ln cc s x l nc u ng dng qu trnh x l sinh hc m qu trnh thng b nh hng mnh bi nhit . Nhit ca nc thi nh hng i sng thy sinh vt, s ha tan oxy trong nc. 2.6. pHpH ca nc thi c mt ngha quan trng trong qu trnh x l. Cc cng trnh x l nc thi p dng cc qu trnh sinh hc lm vic tt khi pH nm trong gii hn t 7 - 7,6. Nh chng ta bit mi trng thun li nht vi khun pht trin l mi trng c pH t 7 - 8. Cc nhm vi khun khc nhau c gii hn pH hot ng khc nhau. Ngoi ra pH cn nh hng n qu trnh to bng cn ca cc b lng bng cch to bng cn bng phn nhm. Nc thi sinh hot pH dao ng trong khong 6,9 - 7,82.7. Nhu cu oxy sinh hc (Biochemical Oxygen Demand, BOD)Nhu cu oxy sinh ha l lng oxy cn thit vi sinh vt oxy ha cc cht hu c trong mt khong thi gian xc nh v c k hiu bng BOD c tnh bng mg/l. Ch tiu BOD phn nh mc nhim hu c ca nc thi. BOD cng ln th nc thi (hoc nc ngun) b nhim cng cao v ngc li.Thi gian cn thit cc vi sinh vt oxy ha hon ton cc cht hu c c th ko di n vi chc ngy ty thuc vo tnh cht ca nc thi, nhit v kh nng phn hy cc cht hu c ca h vi sinh vt trong nc thi. chun ha cc s liu ngi ta thng bo co kt qu di dng BOD5 (BOD trong 5 ngy 20oC). Mc oxy ha cc cht hu c khng u theo thi gian. Thi gian u, qu trnh oxy ha xy ra vi cng mnh hn v sau gim dn2.8. Nhu cu oxy ha hc ( Chemical Oxygen Demand, COD)Ch tiu BOD khng phn nh y v lng tng cc cht hu c trong nc thi, v cha tnh n cc cht hu c khng b oxy ha bng phng php sinh ha v cng cha tnh n mt phn cht hu c tiu hao to nn t bo vi khun mi. Do nh gi mt cch y lng oxy cn thit oxy ha tt c cc cht hu c trong nc thi ngi ta s dng ch tiu nhu cu oxy ha hc. xc nh ch tiu ny, ngi ta thng dng potassium dichromate (K2Cr2O7) oxy ha hon ton cc cht hu c, sau dng phng php phn tch nh lng v cng thc xc nh hm lng COD.2.9. Oxy ha tan(Dissolved oxygen, DO)Oxy ha tan (DO) l mt trong nhng ch tiu quan trng trong qu trnh x l sinh hc hiu kh. Lng oxy ha tan trong nc thi ban u dn vo trm x l thng bng khng hoc rt nh. Trong khi , trong cc cng trnh x l sinh hc hiu kh th lng oxy ha tan cn thit khng nh hn 2mg/l.2.10. Cht hot ng b mt.Cht hot ng b mt l nhng cht hu c gm 2 phn: k nc v a nc, to nn s ha tan ca cc cht trong du v trong nc. Ngun to ra cc cht hot ng b mt l vic s dng cc cht ty ra trong sinh hot. S c mt ca cht hot ng b mt trong nc thi nh hng n tt c cc giai on x l, cc cht ny lm cn tr qu trnh lng v cc ht l lng, to nn hin tng si bt trong cc cng trnh x l, km hm cc qu trnh x l sinh hc.2.11. NitNit c trong nc thi dng cc lin kt dng v c v hu c. Trong nc thi sinh hot, phn ln l lin kt hu c l cc cht c ngun gc protit, thc phm d tha. Cn cc Nit trong cc lin kt v c gm cc dng kh NH4+, NH3 v cc dng oxy ha: NO2" v NO3". Tuy nhin trong nc thi cha x l, v nguyn tc thng khng c NO2" v NO3".2.12. PhotphoPhotpho la mt cht dinh dng a lng cn thit i vi s pht trin ca sinh vt. Vic xc nh Photpho tng l mt thng s ng vai tr quan trng m bo qu trnh pht trin bnh thng ca cc vi sinh vt trong qu trnh x l cht thi bng phng php sinh hc. Photpho v cc hp cht cha Photpho c lin quan cht ch n hin tng ph dng ngun nc, do s c mt qu nhiu ca cc cht ny kch thch s pht trin ca to v vi khun lam.2.13. Kim loi nng2.14. Vi khun v sinh vt khc

Cc vi sinh vt hin din trong nc thi sinh hot bao gm cc vi khun, vi rt, nm, to, ng vt nguyn sinh, cc loi ng v thc vt bc cao.Mc nhim bn vi sinh vt ca ngun nc ph thuc nhiu vo tnh trng v sinh trong khu dn c v nht l cc bnh vin. i vi nc thi bnh vin, bt buc phi x l cc b trc khi x vo h thng thot nc chung hoc trc khi x vo sng h.Ngun nc b nhim bn sinh hc khng s dng ung c, thm ch nu s lng vi khun gy bnh cao th ngun nc ny cng khng th dng cho mc ch gii tr nh bi li, cu c c. Cc loi thy sn trong khu vc nhim khng th s dng l thc n ti sng v n l vt ch trung gian cho cc sinh vt gy bnh.3. Tc ng ca nc thi n mi trng v con ngi:Tc hi ca nc thi n mi trng l do cc thnh phn nhim tn ti trong nc thi gy ra: COD, BOD: s khong ho, n nh cht hu c tiu th mt lng lnv gy thiu ht oxy ca ngun tip nhn dn n nh hng n hsinh thi mi trng nc. Nu nhim qu mc, iu kin ym kh c th hnh thnh. Trong qu trnh phn hu ym kh sinh ra cc sn phm nh H2S, NH3,CH4,..lm cho nc c mi hi thi v lm gim pH ca mi trng. SS: lng ng ngun tp nhn, gy iu kin ym kh. Nhit : nhit ca nc thi sinh hot thng nh hng n i sng ca thu sinh vt nc. Vi trng gy bnh: gy ra cc bnh lan truyn bng ng nc nh tiu chy, ng c thc n, vng da,... N, P: y l nhng nguyn t dinh dng a lng. Nu nng trong nc qu cao dn n hin tng ph dng ho ( s pht trin bng pht ca cc loi to, lm cho nng oxy trong nc rt thp vo ban m gy ngt th v dit vong cc sinh vt, trong khi vo ban ngy nng oxy rt cao do qu trnh h hp ca to thi ra ). Mu: mt m quan. Du m: gy mi, ngn cn khuch tn oxy trn b mt.Nc thi sinh hot gy ra cc tc ng tiu cc n sc khe con ngi v mi trng sng, v vy cn c nhng phng php x l thch hp loi b cc tc ng khng mong mun .

CHNG II: CNG NGH X L NC THI

1. Phng php x l nc thi bng c hc:Phng php ny thng c p dng giai on u ca quy trnh x l, qu trnh c xem nh bc m loi b cc tp cht v c v hu c khng tan hin din trong nc v mt phn cc cht dng keo ra khi nc thi nhm m bo tnh an ton cho cc thit b v cc qu trnh x l tip theo.X l c hc nhm mc ch: Tch cc cht khng ha tan, nhng vt cht c kch thc ln nh nhnh cy, g, nha, l cy, gi rch, du m... ra khi nc thi. Loi b cn nng nh si, thy tinh, ct... iu ha lu lng v nng cc cht nhim trong nc thi. Nng cao cht lng v hiu qu ca cc bc x l tip theo.Ty vo kch thc, tnh cht ha l, hm lng cn l lng, lu lng nc thi v mc lm sch m ta s dng mt trong cc qu trnh sau: lc qua song chn rc hoc li chn rc, lng di tc dng ca lc ly tm, trng trng, lc v tuyn ni.Cc cng trnh x l c hc bao gm:1.1. Song chn rc v li chn rc:Song chn rc hoc li chn rc c chc nng chn gi nhng rc bn th (giy, rau, c, rc), nhm m bo m cho my bm, cc cng trnh v thit b x l nc thi hot ng n nh. Song v li chn rc c cu to bng cc thanh song song, cc tm li an bng thp hoc tm thp c c l ty theo kch c cc mt li hay khong cch gia cc thanh m ta phn bit loi chn rc th, trung bnh hay rc tinh.Theo cch thc lm sch thit b chn rc ta c th chia lm 2 loi: loi lm sch bng tay, loi lm sch bng c gii

Thit b song chn rc t ng Thit b song chn rc th cngLi chn rc dng kh cc cht l lng c kch thc nh, thu hi cc thnh phn qu khng tan hoc khi cn phi loi b rc c kch thc nh. Kch thc mt li t 0,5 ^ 1,0 mm.Li chn rc thng c bao bc xung quanh khung rng hnh tr quay trn (hay cn gi l trng quay) hoc t trn cc khung hnh a.1.2. Thit b nghin rc:L thit b c nhim v ct v nghin vn rc thnh cc ht, cc mnh nh l lng trong nc thi khng lm tc ng, khng gy hi cho bm. Trong thc t cho thy vic s dng thit b nghin rc thay cho thit b chn rc gy nhiu kh khn cho cc cng on x l tip theo do lng cn tng ln nh lm tc nghn h thng phn phi kh v cc thit b lm thong trong cc b (a, l phn phi kh v dnh bm vo cc tuabin. Do vy phi cn nhc trc khi dng.1.3. B lng ct:B lng ct nhm loi b ct, si, dm, cc loi x khi nc thi. Trong nc thi, bn thn ct khng c hi nhng s nh hng n kh nng hot ng ca cc cng trnh v thit b trong h thng nh ma st lm mn cc thit b c kh, lng cn trong cc knh hoc ng dn, lm gim th tch hu dng ca cc b x l v tng tn s lm sch cc b ny. V vy trong cc trm x l nht thit phi c b lng ct.B lng ct thng c t pha sau song chn rc v trc b lng s cp. i khi ngi ta t b lng ct trc song chn rc, tuy nhin vic t sau song chn c li cho vic qun l b lng ct hn. Trong b lng ct cc thnh phn cn loi b lng xung nh trng lng bn thn ca chng. y phi tnh ton th no cho cc ht ct v cc ht v c cn gi li s lng xung cn cc cht l lng hu c khc tri i.B lng ct gm nhng loi sau: B lng ct ngang: C dng nc chuyn ng thng dc theo chiu di ca b. B c thit din hnh ch nht, thng c h thu t u b. B lng ct ng: Dng nc chy t di ln trn theo thn b. Nc c dn theo ng tip tuyn vi phn di hnh tr vo b. Ch dng chy kh phc tp, nc va chuyn ng vng, va xon theo trc, va tnh tin i ln, trong khi cc ht ct dn v trung tm v ri xung y. B lng ct tip tuyn: l loi b c thit din hnh trn, nc thi c dn vo b theo chiu t tm ra thnh b v c thu v mng tp trung ri dn ra ngoi. B lng ct lm thong: trnh lng cht hu c ln trong ct v tng hiu qu x l, ngi ta lp vo b lng ct thng thng mt dn thit b phun kh. Dn ny c t st thnh bn trong b to thnh mt dng xon c qut y b vi mt vn tc trnh hin tng lng cc cht hu c, ch c ct v cc phn t nng c th lng.B lng ct minh ha*Sn phi ct:Cn x ra t b lng ct cn cha nhiu nc nn phi phi kh sn phi ct hoc h cha ct t gn b lng ct. Chung quanh sn phi ct phi c b p cao 1-2m. Kch thc sn phi ct c xc nh vi iu kin tng chiu cao lp ct h chn bng 3-5m/nm. Ct kh thng xuyn c chuyn i ni khc.

1.4. B iu ha:B iu ha c dng duy tr dng thi v nng cc cht nhim vo cng trnh, lm cho cng trnh lm vic n nh, khc phc nhng s c vn hnh do dao ng v nng v lu lng ca qu trnh x l nnguyen tac

Trong hieu khi cong nghe nao can be lang ki khi tuan hoan bunKy khi uasb va be bioga Nguyen ly hoat dong uu nhuoc diem Bun nguy hai tu he thong xu ly qcvn 40 2003Chat thai nguy hai thong tu 12hoat dong be lang dung be lang nganggc thi gy ra v nng cao hiu sut ca qu trnh x l sinh hc. B iu ha c th c phn lm ba loi nh sau: B iu ha lu lng. B iu ha nng . B iu ha c lu lng v nng .Cc phng n b tr b iu ha c th l b iu ha trn dng thi hay ngoi dng thi x l. Phng n iu ha trn dng thi c th lm gim ng k dao ng thnh phn nc thi i vo cc cng on pha sau, cn phng n iu ha ngoi dng thi ch gim c mt phn nh s dao ng . V tr tt nht b tr b iu ha cn c xc nh c th cho tng h thng x l, v ph thuc vo loi x l, c tnh ca h thng thu gom cng nh c tnh ca nc thi.Li ch:-Lm tng hiu qu ca h thng sinh hc do n hn ch hin tng qu ti ca h thng v lu lng cng nh hm lng cc cht hu c, gim c din tch xy cc b sinh hc (do c tnh ton chnh xc hn). Hn na cc cht c ch qu trnh x l sinh hc s c pha long hoc trung ha mc thch hp cho cc hot ng ca vi sinh vt.-Cht lng NT sau x l v vic c c bn y b lng th cp c ci thin do lu lng np cht rn n nh.-Din tch b mt cn cho h thng lc nc gim xung v hiu sut lc c ci thin, chu k lm sch b mt cc thit b lc cng n nh hn.B iu ha minh ha1.5. B lng:B lng tch cc cht khng tan dng l lng trong nc thi theo nguyn tc trng lc. Cc b lng c th b tr ni tip nhau. Qu trnh lng tt c th loi b n 90 ^ 95% lng cn c trong nc thi. V vy, y l qu trnh quan trng trong qu trnh x l nc thi, thng b tr x l ban u hay sau x l sinh hc. c th tng cng qu trnh lng ta c th thm vo cht ng t sinh hc.Lng l phng php n gin nht tch cc cht bn khng ha tan ra khi nc thi. Da vo chc nng v v tr c th chia b lng thnh cc loi: B lng t 1: c t trc cng trnh x l sinh hc, dng tch cc cht rn, cht bn l lng khng ha tan. B lng t 2: c t sau cng trnh x l sinh hc dng lng cc cn vi sinh, bn lm trong nc trc khi thi ra ngun tip nhn Cn c vo chiu dng chy ca nc trong b, b lng cng c chia thnh cc loi ging nh b lng ct trn: b lng ngang, b lng ng, b lng tip tuyn (b lng radian).B lng minh radian minh ha1.6. Lc:Lc c ng dng tch cc tp cht phn tn c kch thc nh khi nc thi, m cc b lng khng th loi c chng. Ngi ta tin hnh qu trnh lc nh cc vt liu lc, vch ngn xp, cho php cht lng i qua v gi cc tp cht li. Vt liu lc c s dng thng l ct thch anh, than cc, hoc si, thm ch c than nu, than bn hoc than g. Vic la chn vt liu lc ty thuc vo loi nc thi v iu kin a phng. C nhiu dng lc: lc chn khng, lc p lc, lc chm, lc nhanh, lc chy ngc, lc chy xuiB lc thng lm vic vi hai ch lc v ra lc. Qu trnh lc ch p dng cho cc cng ngh x l nc thi ti s dng v cn thu hi mt s thnh phn qu him c trong nc thi. Cc loi b lc thng c phn loi nh sau: Lc qua vch lc.( phn ny cn phn bit cc u nhc im v phm vi p dng ca cc phng php lc) B lc vi vt liu lc dng ht. B lc chm. B lc nhanh. Ct lc p lc

B lc minh ha

1.7. B tuyn ni, tch du m:Cc cng trnh ny thng c ng dng khi x l nc thi cng nghip. Nhm loi b cc tp cht c khi lng ring nh hn nc. Cc cht ny s b bt kn l hng gia cc vt liu lc trong b sinh hc...v chng cng ph hy cu trc bn hot tnh trong b Aeroten, gy kh khn trong qu trnh ln men cn.Phng php tuyn ni thng c s dng tch cc tp cht ( dng ht rn hoc lng) phn tn khng tan, t lng km ra khi pha lng. Trong mt s trng hp qu trnh ny cng c dng tch cc cht ha tan nh cc cht hot ng b mt. Qu trnh nh vy c gi l qu trnh tch hay lm c bt.Trong x l nc thi v nguyn tc tuyn ni thng c s dng kh cc cht l lng v lm c bn sinh hc. Qu trnh tuyn ni c thc hin bng cch sc cc bt kh nh (thng l khng kh) vo trong pha lng. Cc kh kt dnh vi cc ht v khi lc ni tp hp cc bng kh v ht ln s ko theo cc ht cng ni ln b mt, sau chng tp hp li vi nhau thnh cc lp bt cha hm lng cc ht cao hn trong cht lng ban u. ng dng cc cng trnh c hc trong x l nc thi Cc cng trnh ng dng Li chn rc Tch cc cht rn th v c th lng Nghin rc Nghin cc cht rn th n kch thc nh hn ng nht B iu ho iu ha lu lng v ti trng BOD v SS Lng Tch cc cn lng v nn bn Lc Tch cc ht cn l lng cn li sau x l sinh hc hoc ha hc Mng lc Tng t nh qu trnh lc, tch to t nc thi sau h n nh Vn chuyn kh B sung v tch kh Bay hi v bay kh Bay hi cc hp cht hu c bay hi t nc thi.B tuyn ni minh ha

1.8. Cng trnh ng t v keo t:Qu trnh lng ch c th tch c cc ht rn huyn ph nhng khng th tch c cc cht gy nhim bn dng keo v ha tan v chng l nhng ht rn c kch thc qu nh. tch cc ht rn mt cch hiu qu bng phng php lng cn tng kch thc ca chng nh s tc ng tng h gia cc ht phn tn lin kt thnh tp hp cc ht nhm lm tng vn tc lng.Kh cc ht keo rn bng trng lng cn theo 2 bc: Trung ha in tch ca chng. Lin kt chng li vi nhau. Qu trnh trung ha in tch: qu trnh ng t. Qu trnh lin kt to thnh cc bng ln hn: qu trnh keo t.

Cc cht ng t thng dng: cc mui nhm, st hoc hn hp ca chng. Vic la chn ph thuc vo: tnh cht ha l, chi ph, nng tp cht trong nc, pH, thnh phn mui trong nc. Hay dng:Al2(SO4)3.18H2O, NaAlO2, NH4Al(SO4)2.12H2O,KAl(SO4)2.12H2O, FeCl3, Fe2(SO4)3.2H2O trong Al2(SO4)3 c dng nhiu hn v d ha tan trong nc.Al2(SO4)3 + 3Ca(HCO3)2Al(OH)3 + 3CaSO4 + 6CO2i vi cc mui st cng hay dng:FeCl3 + 3 H2O Fe(OH)3 + HCl( phng trnh sai)V n nhiu u im hn so vi cc mui nhm do: tc dng tt hn nhit thp, c khong pH ti u ca mi trng rng hn, bn ln v kch thc bng keo c khong gii hn rng ca thnh phn mui, c th kh c mi v khi c H2S. Nhc im: to cc phc ha tan nhum mu qua phn ng ca cc cation st vi mt s hp cht hu c.

2. Phng php x l bng sinh hc:Nguyn tc ca phng php ny l s dng cc vi sinh vt k kh v vi sinh vt tu nghi phn hu cc hp cht hu c v v c c trong nc thi, iu kin khng c oxi ho tan vi nhit ,Ph thch hp cho cc sn phm dng kh (ch yu l CO2, CH4).Qu trnh phn hu k kh cht bn c th m t bng s tng qut:(CHO)n NS + CO2 + H2O + CH4 + NH4 + H2 + H2S + T bo VI SINH( phng trnh khng r )Trong 10 nm tr li y do cng ngh sinh hc pht trin, qu trnh x l k kh trong iu kin nhn to c p dng x l cc loi b cn cht thi cng nghip, sinh hot cng nh cc loi nc thi m c c hm lng cht bn hu c cao: BOD > 10 - 30 (g/l).Hin nay cc nh khoa hc ang c gng u t nghin cu ng dng t phng th nghim n quy m pilot vi cc m hnh c th tch nh n quy m ln. c trn di vi chc nh my x l sinh hc k kh nc thi cc nc nh H Lan, Hoa K, Thy S, Cng ho lin bang c.. .do phng php c cc u im: Thit k n gin, th tch cng trnh nh, chim t din tch mt bng; cng trnh c cu to kh n gin v gi thnh khng cao; chi ph vn hnh v nng lng thp; kh nng thu hi nng lng - Biogaz cao; khng i hi cung cp nhiu cht dinh dng; lng bn sinh ra t hn 10 - 20 ln so vi phng php hiu kh v c tnh n nh tng i cao c th tn tr trong mt thi gian kh di v l mt ngun phn bn c gi tr; ti trng phn hu cht bn hu c cao. Chu c s thay i t ngt v lu lng.( ci ny ch i vi k kh, cn hiu kh th u nhc im nh th no)Ngoi cc u im trn phng php cng c nhng hn ch l rt nhy cm vi cc cht c hi vi s thay i bt thng v ti trng ca cng trnh; x l nc thi cha trit ; nhng hiu bit v cc vi sinh vt k kh cn hn ch; thiu kinh nghim v vn hnh cng trnh.Cng trnh x l sinh hc thng c t sau khi nc thi c x l s b qua cc cng trnh c hc, ha hc, ha l.2.1. Cng trnh x l trong iu kin t nhin :a. Cnh ng ti, cnh ng lc:Vic x l nc thi bng cnh ng ti, cnh ng lc da trn kh nng gi cc cn nc trn mt t, nc thm qua t nh i qua lc. Nh c oxy trong l hng v mao qun ca lp t, cc VSV hiu kh hot ng phn hy cc cht hu c nhim bn, cng xung su lng oxy cng t v qu trnh oxy ha cc cht hu c gim dn. Qu trnh oxy ha nc thi ch xy ra lp nc mt su 1,5m.Cnh ng ti v cnh ng lc l nhng mnh t c san phng hay to dc khng ng k v c ngn cch to thnh cc bng cc b t.b. H sinh hc:y l phng php x l n gin nht v c p dng t xa. Phng php ny cng khng yu cu k thut cao, vn u t t, chi ph hot ng thp, qun l n gin v hiu qu cng kh cao. Quy trnh c tm tt nh sau:Nc thi loi b rc, ct, si... Cc ao h n nh Nc xl. H hiu kh:Ao nng 0,3 - 0,5 m c qu trnh oxy ha cc cht bn hu c ch yu nh cc vi sinh vt. gm 2 loi: H lm thong t nhin v h lm thong nhn to.( kim tra li mnh phn ny) H k kh:Ao k kh l loi ao su, t hoc khng c iu kin hiu kh. Cc vi sinh vt k kh hot ng sng khng cn oxy ca khng kh. Chng s dng oxy t cc hp cht nh nitrat, sulfat... oxy ha cc cht hu c v cc loi ru v kh CH4, H2S,CO2,...v kh v nc. Chiu su ca h kh ln khong 2 - 6 m.( kim tra li) H ty nghi:L s kt hp hai qu trnh song song: phn hy hiu kh cc cht hu c ha tan c u trong nc v phn hy k kh (ch yu l CH4) cn lng vng lng.Ao h ty nghi c chia lm ba vng: Lp trn l vng hiu kh, vng gia l vng k khi ty tin v vng pha y su l vng k kh. Chiu su ca h khong 1 - 1,5 m.2.2. Cc cng trnh x l hiu kh nhn to:X l sinh hc hiu kh trong iu kin nhn to c th k n hai qu trnh c bn:+ Qu trnh x l sinh trng l lng.+ Qu trnh x l sinh trng bm dnh.Cc cng trnh tng thch ca qu trnh x l sinh hc hiu kh nh: Aeroten bn hot tnh (vi sinh vt l lng), b thi kh sinh hc tip xc (vi sinh vt bm dnh), b lc sinh hc, thp lc sinh hc, b sinh hc tip xc quay...

a. Cng trnh x l sinh hc hiu kh:Qu trnh x l nc thi s dng bn hot tnh da vo s hot ng sng ca si sinh vt hiu kh. Trong b Aeroten, cc cht l lng ng vai tr l cc ht nhn cho vi khun c tr, sinh sn v pht trin dn ln thnh cc bng cn gi l bn hot tnh. Bn hot tnh l cc bng cn c mu nu sm cha cc cht hu c hp th t nc thi v l ni c tr pht trin ca v s vi khun v vi sinh vt khc. Cc vi sinh vt ng ha cc cht hu c c trong nc thi thnh cc cht dinh dng cung cp cho s sng. Trong qu trnh pht trin vi sinh vt s dng cc cht sinh sn v gii phng nng lng, nn sinh khi ca chng tng ln nhanh. Nh vy cc cht hu c c trong nc thi c chuyn ha thnh cc cht v c nh H2O, CO2 khng c hi cho mi trng.Qu trnh sinh hc c th din ra tm tt nh sau:Vi sinh vt + cht hu c + O2 -> CO2 + H2O +Vi sinh vt mi.Hay c th vit:Cht thi + Bn hot tnh + Khng kh => Sn phm cui + Bn hot tnh d. B AerotenB Aeroten l cng trnh b tng ct thp hoc bng st thp, hnh khi ch nht hoc hnh trn. Nc thi chy qua sut chiu di b v c sc kh, khuy o nhm tng cng oxy ho tan trong nc, thc y qu trnh phn hu cht hu c ca vi sinh vt hiu kh. Qu trnh phn hu cc cht hu c xy trong Aeroten bao gm ba giai on Giai oan mt: thc n dinh dng trong nc rt phong ph, lng sinh khi trong thi gian ny li t. Sau khi thch nghi vi mi trng, vi sinh vt sinh trng rt nhanh v mnh theo cp s nhn, v vy lng oxy tiu th tng dn Giai oan hai: sinh vt pht trin n nh, tc tiu th oxy cng gn nh t thay i chnh giai on ny cht hu c b phn hu nhiu nht Giai on ba: Sau mt thi gian kh di, tc oxy ho cm chng, c chiu hng gim li thy tc tiu th oxy tng ln. y l giai on nitrat ho mui amon.

>9S cng ngh b Aeroten

B lc sinh hcL cng trnh c thit k nhm mc ch phn hy cc cht hu c c trong nc thi nh qu trnh oxy ha din ra trn b mt vt liu tip xc. Trong b cha y vt liu tip xc, l gi th cho vi sinh vt sng bm. C 2 dng: B lc sinh hc nh git: L b lc sinh hc c lp vt liu lc khng ngp nc. Gi tr BOD ca nc thi sau khi lm sch t ti 10 ^ 15mg/l. Vi lu lng nc thi khng qu 1000 m3/ngy. B lc sinh hc cao ti: Lp vt liu lc t ngp trong nc. Ti trng nc thi ti10 ^ 30m3/m2ng tc l gp 10 ^ 30 ln b lc sinh hc nh git.

Lc sinh hc RBCLc sinh hc RBC (Rotating Biological Contactor) l cng ngh tin tin trong x l nc thi nhm gim thiu cc cht nhim cacbon (BOD) hoc BOD/nitrat ho ng thi l cng ngh tit kim nng lng, tit kim chi ph x l. RBC c nghin cu v pht trin ti c vo nhng nm 1960, n nay h thng RBC c ng dng rng ri ti 140 quc gia trn th gii. cc loi nc thi thch hp cho h thng l nc thi c ngun gc sinh hot nh nc thi ti cc to nh, khu dn c, bnh vin v nc thi mt s ngnh sn xut cng nghip. Nguyn l hot ng Da vo nguyn l tip xc ca h vi sinh vt bn dnh trn a quay (mng sinh hc) i vi nc thi v xy c trong khng kh. Khi khi a quay ln, cc vi sinh vt ly xy oxy ho cc cht hu c v gii phng CO2. Khi khi a quay xung, vi sinh vt nhn cht nn (cht dinh dng) c trong nc. Qu trnh tip din nh vy cho n khi h vi sinh vt sinh trng v pht trin s dng ht cc hu c c trong nc thi. Cu to H thng gm mt lot cc a trn, phng c lm bng PVC (Poly vinyl clorua) hoc PS (Poly styren) lp trn cng mt trc thp nm ngang cch nhau mt khong nh. Cc a ny c t ngp vo nc mt phn (khong 30-40% theo ng knh, c khi ngp ti 70-90%) v quay chm khi lm vic.y l thit b x l nc thi k thut mng sinh hc da trn s sinh trng gn kt ca vi sinh vt trn b mt ca cc vt liu a. H vi sinh vt hiu kh sinh trng v pht trin c nh trong lp mng bm trn b mt a. Khi trc quay, lp mng vi sinh vt c lun phin tip xc vi cht hu c (cht bn) trong nc thi v ly oxy t khng kh oxy ha cc cht hu c v gii phng CO2. Nh , nc thi c lm sch vi hiu sut x l BOD5 > 90% v nito > 35%.

u im Thit b lm vic t hiu qu x l cht hu c (BOD) trn 90%; cht dinh dng (N, P) t trn 35%; Khng yu cu tun hon bn. Khng yu cu cp kh cng bc. Hot ng n nh, t nhy cm vi s bin i lu lng t ngt v tc nhn c vi vi sinh; T ng vn hnh. Khng yu cu lao ng c trnh cao; Khng gy mi, n thp, tnh thm m cao; Thit k theo n nguyn, d dng thi cng theo tng bc, tit kim s dng mt bng. RBC c s dng vi cc loi nc thi cha hm lng nhim cht hu c BOD5 500 mg/l, dinh dng N tng 100 mg/l. B sinh hc theo m SBR (Sequence Batch Reactor)SBR l mt b dng ca b Aeroten. Khi xy dng b SBR nc thi ch cn i qua song chn rc, b lng ct v tch du m nu cn, ri np thng vo b. u im l kh c cc hp cht Nit, photpho khi vn hnh ng quy trnh hiu kh, thiu kh v ym kh.B SBR hot ng theo 5 pha: Pha lm y (fill): Thi gian bm nc vo b ko di t 1 - 3 gi. Dng nc thi c a vo b trong sut thi gian din ra pha lm y. Trong b phn ng hot ng theo m ni tip nhau, ty thuc vo mc tiu x l, hm lng BOD u vo, qu trnh lm y c th thay i linh hot: Lm y - tnh, lm y - ha trn, lm y sc kh. Pha phn ng, thi kh (React): To phn ng sinh ha gia nc thi v bn hot tnh bng sc kh hay lm thong b mt cung cp oxy vo nc v khuy trn u hn hp. Thi gian lm thong ph thuc vo cht lng nc thi, thng khong 2 gi. Trong pha phn ng, qu trnh nitrat ha c th thc hin, chuyn nit t dng N-NH3 sang N-NO22- v nhanh chng chuyn sang dng N-NO3-. Pha lng (settle): Lng trong nc. Qu trnh din ra trong mi trng tnh, hiu qu thy lc ca b t 100%. Thi gian lng trong v c c bn thng kt thc sm hn 2 gi. Pha rt nc (draw): Khong 0.5 gi. Pha ch: Ch i np m mi, thi gian ch ph thuc vo thi gian vn hnh 4 quy trnh trn v s lng b, th t np nc ngun vo b.X bn d l mt giai on quan trng khng thuc 5 giai on c bn trn, nhng n cng nh hng ln n nng sut ca h. Lng v tn xut x bn c xc nh bi nng sut yu cu, cng ging nh h hot ng lin tc thng thng. Trong h hot ng gin on, vic x thng c thc hin giai on lng hoc giai on tho nc trong. c im duy nht l b SBR khng cn tun hon bn hot ha. Hai qu trnh lm thong v lng u din ra ngay trong mt b, cho nn khng c s mt mt bn hot tnh giai on phn ng v khng phi tun hon bn hot tnh gi nng .

Qu trnh vn hnh b SBR

b. Cc cng trnh x l sinh hc k kh:Phn hy k kh (Anaerobic Descomposotion) l qu trnh phn hy cht hu c thnh cc cht kh (CH4 v CO2) trong iu kin khng c oxy. Vic chuyn ha cc acid hu c thnh kh mtan sn sinh ra t nng lng. Nng lng hu c chuyn ha thnh kh vo khong 80 - 90%.Hiu qu x l ph thuc vo nhit nc thi, pH, nng MLSS. Nhit thch hp cho phn ng sinh kh l t 32 - 35 c.u im ni bt ca qu trnh x l k kh l lng bn sinh ra rt thp, v th chi ph cho vic x l bn thp hn nhiu so vi cc qu trnh x l hiu kh.Trong qu trnh ln men k kh, thng c 4 nhm vi sinh vt phn hy vt cht hu c ni tip nhau: Thy phn: Cc vi sinh vt thy phn (Hydrolytic) phn hy cc cht hu c dng polyme nh cc polysaccharide v protein thnh cc cc phc cht n gin hoc cht ha tan nh amino acid, acid bo.... Kt qu ca s b gy mch cacbon cha lm gim COD. Acid ha: giai on ny, vi khun ln men chuyn ha cc cht ha tan thnh cht n gin nh acid beo d bay hi, alcohols cc axt lactic, methanol, CO2, H2, NH3, H2S v sinh khi mi. s hnh thnh cc acid c th lm ph gim xung 4.0. Acetic ha (acetogenesis):Vi khun acetic chuyn ha cc sn phm ca giai on acid ha thnh acetate, H2, CO2 v sinh khi mi. Metan ha (methanogenesis): y l giai on cui cng ca qu trnh phn hy k kh. Axt acetic, H2, CO2, axt formic v methanol chuyn ha thnh mtan, CO2 v sinh khi B UASB ( Upflow anaerobic Sludge Blanket).Nc thi c a trc tip vo pha di y b v c phn phi ng u, sau chy ngc ln xuyn qua lp bn sinh hc dng ht nh (bng bn) v cht hu c b phn hy.Cc bt kh mtan v NH3, H2S ni ln trn v c thu bng cc chp thu kh dn ra khi b. Nc thi tip theo chuyn n vng lng ca b phn tch 2 pha lng v rn. Sau ra khi b, bn hot tnh th hon lu li vng lp bng bn. S to thnh bn ht v duy tr c n rt quan trng khi vn hnh UASB.Thng cho thm vo b 150 mg/l Ca2+ y mnh s to thnh htbn v 5 - 10 mg/1 Fe2+ gim bt s to thnh cc si bn nh. duy tr lp bng bn trng thi l lng, tc dng chy thng ly khong 0,6 - 0,9 m/h.

chuyn : Cng ngh x l nc thi

*B UASB.1. u vo, 2. u ra, 3. Biogas 4. Thit b gi bn (VSV), 5. Khu vc c t bn hn21

Hin nay, nc thi ti cc khu chung c ti Vit Nam phn ln u cha c x l thi ra ngun tip nhn gy ra nhng nh hng tiu cc n mi trng v sc khe con ngi. V vy, vic p dng cc bin php k thut x l nc thi sinh hot ti cc khu chung c l vic lm cn thit nhm loi b cc tc ng tiu cc .3. Phng php x l bng ha hc v ha l:

3.1. Phng php ng t:Mc ch: tng nhanh qu trnh lng cc cht l lng phn tn nh, keo,... ngi ta dng phng php ng t, khi nng cht mu, mi, l lng s gim xung.Cc cht ng t thng dng l nhm sunfat, st sunfat, st clorua,...Al2(SO4)3 khi vo nc s tc dng vi bicacbonat trong nc to thnh Al(OH)3 dng bng v s hp ph , kt dnh cc ht huyn ph, cc cht dng keo llng trong NT. Cc bng ny s lng xung y dng cn.Al2(SO4)3 + 3Ca(HCO3)2 2Al(OH)3 + 3CaSO4 + CO2 Khi dng cc mui st:2FeCl3 + 3Ca(OH)2 3CaCl2 + 2Fe(OH)3Hiu sut ng t cao nht khi pH 4-8,5. to cc bng ln, d lng ngi ta dng thm cht tr ng. l cht cao phn t tan trong nc v d phn ly thnh ion, gm cht tr ng t loi anion v cation. Hay dng l poliacrylamit (CH2CHCONH2)n , natri silicat hot tnh,...Gii hn s dng: chn la ha cht, liu lng ti u, th t cho vo nc, lng cn to thnh,... phi c tin hnh bng thc nghim, thng dng 1-5mg/l.iu kin: phn ng din ra hon ton v tit kim, cn phi: khuy u c th s dng cc loi my trn khc nhau. Loi hay dng: cnh qut c gii th NT s chuyn ng vng v to bng d dng ton b th tch.3.2. Phng php trung ha:Nc thi sn xut trong nhiu lnh vc c cha nhiu axit hoc kim. ngn nga hin tng xm thc cc cng trnh thot nc v trnh cho cc qu trnh sinh ha cc cng trnh lm sch v trong h, sng khng b ph hoi, ngi ta phi trung ha cc loi nc thi . Trung ha cn vi mc ch lm cho mt s mui kim loi nng lng xung v tch ra khi nc.( xem li gip mnh xem mc ch ny ng hay khng)Cng ngh u tin: tnh n kh nng trung ha ln nhau gia cc loi NT cha axit vkim.Qu trnh trung ha c thc hin trong cc b trung ha kiu lm vic lin tc haygin on theo chu k. nc thi sau khi trung ha c th cho lng cc h lng tp trung v nuiu kin thun li, cc h ny c th tch c th tr c cn lng trong khong 10-15 nm.Th tch cn lng ph thuc vo nng axit, ion kim loi nng trong NT, vo dng v liu lng ha cht, vo mc lng trong,...V d: khi trung ha NT bng vi sa ch bin t vi th trng cha 50% CaO hot tnh s to nhiu cn nht.Vic la chn bin php trung ha ph thuc vo lng NT, ch x thi, nng , ha cht c a phng.i vi NT sn xut, vic trung ha bng ha cht kh kh khn v thnh phn v lu lng NT trong cc trm trung ha dao ng rt ln trong ngy m. Ngoi vic cn thit phi xy dng b iu ha vi th tch ln cn phi c thit b t ng iu chnh lng ha cht vo. Thng s chnh iu chnh ph bin l i lng pH. Trong thc t cn phi tin hnh thc nghim vi tng loi NT tin hnh bin php trung ha v trong NT ny cha nhiu hp cht hu c, axit, mui phn ly yu c nh hng n vic o pH bng in ha hc.a. Trung ha bng cch trn NT cha axit v NT cha kim:Phng php ny c dng khi NT ca x nghip l axit cn x nghip gn c NT kim. C hai loi NT ny u khng cha cc cu t gy nhim khc.b. Trung ha NT bng cch cho thm ha cht:Nu NT cha qu nhiu axit hay kim ti mc khng th trung ha bng cch trn ln chng vi nhau c th phi cho thm ha cht.Phng php ny thng trung ha axit.Ha cht s dng: ph liu cng nghip a phng trung ha axit v c c th dng bt k dung dch c tnh baz no. Ha cht r tin v d kim l Ca(OH)2, CaCO3, MgCO3, lmit, cn NaOH v xa Na2CO3 ch c dng khi chng l ph liu.Liu lng ha cht c xc nh theo iu kin trung ha hon ton axit t do v ly ln hn tnh ton mt cht.Vic a dung dch cng tc vo nc thi c tin hnh nh bm hoc cc thit b nh lng (kiu phao, nh mc vi p lc c nh,...)

c. Trung ha nc thi cha axit bng cch lc qua nhng lp vt liu trung ha:S dng cho NT cha HCl, HNO3, H2SO4 vi hm lng di 5g/l v khng cha mui kim loi nng.Cch tin hnh: cho NT tip xc cc b vt liu lc l vi, magiezit, hoa cng, lmit,. kch thc ht 3-8 cm vi tc ph thuc vo vt liu nhng khng qu 5m3/h v thi gian tip xc khng qu 10 pht, nc thi c th chuyn ng ngang hoc ng trong b lc.d. . Dng kh thi, khi t l hi trung ha NT cha kim:y l bin php kh kinh t trung ha NT cha kim v kh t ng khi chy tt thng cha khong 14% CO..3.3. Phng php oxy ha kh:Cc cht bn trong NT cng nghip c th phn ra hai loi: v c v hu c.Cc cht hu c thng l m, m, ng, cc hp cht cha phenol, cha nit,... nn c th b phn hy vi sinh vt, do c th dng phng php sinh hc x l.Cc cht v c thng l nhng cht khng x l bng phng php sinh hc c. Cc ion kim loi nng khng th XL bng VSV cng nh khng loi c di dng cn, ch 1 phn b hp ph bng BHT. Thy ngn, asen,...cn l nhng cht rt c kh XL m cn tiu dit cc VSV c li trong NT.a. XLNT cha xianua bng phng php oxy ha kh:Vic la chn bin php XLNT ph thuc vo tnh cht l ha ca NT. Cch thc thng dng l oxy ha xianua chuyn sang dng xianat, feri, fero, cc cn kt ta t nhng xianua n gin, phc cht ri sau tch khi nc thi bng phng php lng hoc lc.Cn u tin la chn bin php oxy ha xianua c thnh xianat khng c v y l bin php tt nht. y, nhm CN" b phn hy hon ton v nc s khng nhim bn tr li bi cc cht xianua.

Mt s cc cht hay dng: Dng hypoclorit:+ oxy ha xianua n gin, tan c: CN- + OCl-CNO- + Cl-+ oxy ha xianua phc hp, tan, c .) Dng clo lng trong mi trng kim:+ oxy ha xianua n gin, tan c: CN- + Cl2 + .OH- CNO- + Cl-+ H.O+ oxy ha xianua phc hp, tan c: Dng permanganat:+ oxy ha xianua n gin, tan c:+ oxy ha xianua phc hp, tan c:Lu :- qu trnh oxy ha l nh oxi nguyn t mi sinh, khng phi l O2 nn nu lm thong th xianua khng th b oxy ha c m ch mt phn b thi i m thi.b. XLNT cha crom bng phng php oxy ha kh:-Nguyn tc: chuyn Cr6+ s bin v Cr3+, tip tch dng hidroxit kt ta.-Cc cht kh c th dng: Na2S, Na2SO3, NaHSO3, FeSO4, SO2, khi cha kh SO2,...-Cc phn ng chuyn Cr6+ v Cr3+:Cr2O72- + 3S2 + 14H+2Cr3+ + 3S0 + 7H2OCr2O72- + 3HSO3' + 5H+ 2Cr3+ + 3SO42' + 4H2OCr2O72- + 6Fe2- + 14H+2Cr3+ + 6Fe3+ + 7H2ONu dng nc Na2S th trong dung dch Na2S b thy phn mnh v to kt ta Cr(OH)3 nn khng cn thm vi: S2- + 2H2O H2S + 2OH'Nu dng NaHSO3, FeSO4 th cn cho thm vi sa (hoc loi kim no ) kt ta Cr(OH)3.Cng ngh x l nh sau: u tin NT c iu ha lu lng v nng . Sau kim tra pH nu thy pH > 4 cn iu chnh sao cho pH 2-4 trc khi thc hin phn ng kh, ng thi cn xc nh lng Cr6+ tnh ton lng cht kh ( thng dng gp 1,25 ln lng tnh ton theo l thuyt).Cht kh thng c chun b di dng dung dch 10% v cho vo b phn ng nh thit b nh lng. Thi gian khuy trn b phn ng di 30 pht, sau khi phn ng kh kt thc cho vi sa vo ( c chun b vi nng khong 2,5%) cho t pH 9, tip tc khuy khong 3-5 pht sau cho NT sang b lng vi thi gian khong 2h.

3.4. Phng php oxy ha in ha:c dng x l NT vi mc ch phn hy cc cht c trong NT hoc thu hi cc kim loi qu trn in cc.p dng: X l NT cc phn xng m niken, m bc, cc nh my lm giu kim loi, phn xng ty ra g kim loi.V d: trn cc anot c th thu hi khong 60-70% ng trong NT cha cc hp cht ng xianua bng oxy ha in ha.V d: in phn cc dung dch cha st sunfat v axit sunfuaric t do bng mng trao i anion s phc hi ti 80-90 % axit sunfuaric v thu hi wc bt st vi lng 20-50 kg/m3 dung dch.Nu dng phng php in phn, NT sau x l c th dng li chun b cho cc dung dch m v dung dch axit sunfuaric c th dng li cho cc qu trnh in phn sau. Theo kinh nghim cc nghin cu v thc t cho thy: nu nc thi cha xianua vi nng ln hn 1g/l dung phng php in phn s r tin hn so vi phng php dung ha cht.

CHNG III: MT S CNG TRNH V CNG NGH X L NC THI

1. Mt s h thng x l nc thi p dng ph bin:1.1. Cng ngh x l nc p dng ti nh cng ty c phn gm Vit Thnh:

SCRB IU HOB TUYN NILNG 1H THU BNLNG 2AEROTANKB KH TRNGMY NN BNNGUN TIP NHN, CT A TCVN-5945, 1995BunBunHO THUBunBun tuan hoanQuy trnh x l nc thi gm m ngh cng ty c phn gm Vit Thnh( xem li )

Thuyt minh quy trnh cng ngh:Nc thi t nh my c tp trung ti mng dn qua li chn rc, tip tc chy vo h thu gomNc t h thu c dn vo b iu ho iu ho lu lng v nng . Hai bm t cui b bm nc ln bnh to p, kh c sc vo b iu ho t my thi kh ngn nga hin tng lng xy ra v mt phn to ra mi trng hiu kh c tc dng tng hiu qu x l cng trnh x l sinh hc pha sau.Kh c sc vo b to p c tc dng to s bo ho kh. Nc thi c dn t b to p vo b tuyn ni t y b. Du, m c thu gom bi mt dn gt du t trn b mt b tuyn ni. Sau khi qua b tuyn ni nc thi t chy vo b lng ITi b lng I cc cht hu c v v c lng c s b gi li. Ti y cn c thit b vt vng ni, lng vn ny cng vi lng du m b tuyn ni c thu gom a n h thu bn. Bn b lng I s c bm n b cha bn, cn nc thi sau lng s t chy qua b Aerotank.Ti b Aerotank c h thng ng ng dn kh v cc a phun kh. Kh phn phi ra vi vn tc cao theo tnh ton nc thi v bn hot tnh tip xc v lng oxy cung cp tt nht to iu kin cho vi sinh vt hiu kh tip xc vi thc n v oxy.Nc thi t b Aerotank t chy qua b lng II, nc thi sau lng II t chy vo b kh trng theo trng lc. Nc sau khi c kh trng c thi ra ngun tip nhn l sng ng Nai, t chun A (TCVN 5945, 1995)( cng ngh t chun lu,cn a ra cng ngh ang p dng ti nahf my t chun QCVN 40:2011)

1.2. Cng ngh x l nc thi c p dng ti nh my ch bin sa Vinamilk thng nht:(xem li, phm b UASB ng khng hay l b biogas,ni chung xem k li s c ng cha)

Dinh dngMy thi khMy thi khNgun tip nhnQCVN 40/2011 BTNMT (loi B)Hm tip nhn Song chn rcB iu haB tuyn niB UASBB AerotankB lng Chnh pHNc thiB lc p lcDu mBn dBn tun hon Ch thchng ng dn nc thi ng ng dn bnng ng dn khng ng dn nc tch bn My nn khDung dch cloB kh trngB nn bnMy p bnXe ch bnNc tch bn B trung gianQui trnh x l nc thi nh my ch bin sa vinamilk Thng Nht Thuyt minh quy trnh cng ngh:Ton b nc thi t cc cng on sn xut, khu sinh hot ca cng nhn, nh v sinh s c tp trung n trm x l. Nc thi qua Song chn rc:Nc thi t hm tip nhn, chy qua Song chn rc loi b cc tp cht th c kchthc to nh bao nilong, giy, vi vnv theo mng dn chy vo b iu ha. Cc tp cht ny c th gy ra s c trong qu rnh vn hnh h thng nh lm h hng bm tc nghn ng ng mng dn. Rc dnh trc song phi c co i bng c gii hoc bng phng php th cng. Rc c th tp trung li a n bi rc hoc n b phn hy bn. Nc thi t song chn rc chy sang B iu ha:B iu ha l ni tp trung nc thi t cc khu vc lm vic khc nhau, thnh mt ngun thi duy nht.Lu lng v cht lng nc thi thng xuyn dao ng theo cc gi trong ngy. Khi h s khng iu ha K 1,4 th xy dng b iu ha cc cng trnh x l lm vic vi lu lng u trong ngy s kinh t hnMc ch: Do tnh cht nc thi thay i theo tng gi sn xut v ty tnh cht nc thi ca tng cng on. V vy, b iu ha rt cn thit trong vic iu ha nng v lu lng nc thi, lm gim kch thc v to ch lm vic n nh lin tc cho cc cng trnh pha sau, trnh s c qu ti.Ngun nc thi u vo c pH vt qu ngng cho php v thay i theo tng cng on sn xut. Trong khi , qu trnh x l nc thi bng phng php sinh hc rt nhy cm vi s dao ng ca tr s pH, n i hi gi tr pH phi trong khong 6.5 n 8.5 ( ti u l 6.8 n 7.4). Do , ti b iu ha cn b tr thit b iu chnh pH t ng. u d t ng trong thit b kt hp vi h bm nh lng v ha cht gip ngun nc thi lun c pH n nh. Nc thi t b iu ha chy sang b tuyn ni:Ti b tuyn ni cn nh kh lng, du, m c tch ra khi nc. Qu trnh tch cn, du, m xy ra khi ha tan vo nc nhng bt kh nh, cc bt ny bm vo cc ht cn lm cho t trng ca t hp cn kh gim, v lc y ni ln y hn hp cn, kh ni ln mt nc v c gt ra ngoi.Qu trnh tuyn ni ph thuc rt nhiu vo loi ht b mt l lng, v vy th nghim qui m phng th nhim v qui m va (pilot scale) cn c xy dng tm cc thng s thit k hp l. Yu t cn quan tm trong thit k cng trnh tuyn ni bao gm: hm lng cht l lng, lng kh s dng, vn tc ni ca ht v ti trng cht rn.Trong tuyn ni kh ha tan, khng kh ha tan trong nc thi p sut vi atmosphere (275 350 kPa), sau p sut gim xung p sut kh quyn, kh ha tan tch ra khi nc thnh nhng bt kh mn. Hiu qu ca qu trnh tuyn ni ny ph thuc vo t s th tch kh trn khi lng cht rn (A/S). T s ny ph thuc nhiu vo loi cht l lng, v phi c xc nh bng thc nghim. Nc thi t b tuyn ni chy sang B UASB:Nh vo s hot dng phn hy ca cc vi sinh vt k kh bin i cht hu c thnh cc dng kh sinh hc. Chnh cc cht hu c tn ti trong nc thi l cc cht dinh dng cho cc vi sinh vt.S pht trin ca vi sinh vt trong b thng qua 3 giai on: Giai on 1: Nhm vi sinh vt t nhin c trong nc thi thy phn cc hp cht hu c phc tp thnh cc cht hu c n gin c trng lng nh nh Monosacarit, amino axit to ra ngun thc n v nng lng cho vi sinh hot ng. Giai on 2 : Nhm vi khun to men axt bin i cc hp cht hu c n gin thnh cc axt hu c thng l axt acetic, nhm vi khun ym kh to axt l nhm vi khun axit focmo. Giai on 3: Nhm vi khun to mtan chuyn ha hydro v axit acetic thnh kh mtan v cacbonic. Nhm vi khun ny gi l Mtan Focmo.Vai tr quan trng ca nhm vi khun mtanfocmo l tiu th hydro v axit acetic, chng tng trng rtchm v qu trnh x l ym kh cht thi c thc hin khi kh mtan v cacbonic thot ra khi hn hp.Hiu qu x l ph thuc vo cc yu t mi trng nh nhit , pH Cc yu t sinh vt nh : s lng v kh nng hot ng phn hy ca qun th vi sinh vt c trong b. Hiu qu x l theo COD t 60 80 %. Nc thi t b UASB chy sang B Aerotank:Ti b AEROTANK ,cc cht hu c cn li s c tip tc phn hy bi cc vi sinh vt hiu kh.Qu trnh oxi ha trong b AEROTANK xy ra qua 3 giai on : Giai on 1: Tc oxy ha xc nh bng tc tiu th oxi . Giai on 2 : Bn hat tnh khi phc kh nng oxi ha, ng thi oxi ha nhng cht hu c cn li . giai on ny, tc oxy ha cng xc nh bng tc tiu th oxi nhng nh hn giai on 1 (tc oxy ha giai on 2 bng 1/3 tc oxy ha giai on 1). Giai on 3: giai on nitr ha cc amon. Xy ra sau mt thi gian di, tc oxy ha cm chng.Bn hot tnh l loi bn xp c cha nhiu vi sinh vt c kh nng oxy ha v khong ha cc cht hu c c trong nc thi. gi cho bn hot tnh trng thi l lng v m bo cho oxi dng cho cc qu trnh oxi ha cc cht hu c th phi lun lun duy tr vic cung cp kh. S lng qun th vi sinh vt trong bn hot tnh ph thuc vo nhiu yu t nh thnh phn cht thi, hm lng cc cht thi, lng oxy ha tan, ch thy ng hc ca b. S lng vi khun trong bn hot thh dao ng trong khong 108 : 10 12 khun lc/mg MLSS. Phn ln, chng thuc cc chng sau: Pseudomonas, Achromobacteria, Alkligches, Bacillus, Micrococcus, Flavobacrerium.Trong bn hot tnh lun c mt ca cc vi khun nitrit: Nitrosomonas v nitrobacter. Vi khun nitrat Sphacrotilus v cladothric.Hiu qu x l ca b tc AEROTANK t t 75%: 95% v ph thuc cc yu t nh nhit , pH, nng oxy, lng bn nc th sau khi qua b AEROTANK cc cht hu c d phn hy sinh hc b loi hon ton . Nc thi t b Aerotank chy sang B lng ly tm:Sau khi qua b Aerotank, hu ht cc cht hu c ha tan trong nc thi b loi hon ton. Tuy nhin, nng bn hot tnh c trong nc thi l rt ln, do vy bn hot tnh v cc cht rn l lng s c tch b lng. Nc thi t b lng ly tm chy sang b trung gian:Nh b trung gian, nc thi c n nh, sau bm trc tip vo b lc p lc. Nc thi t b trung gian chy sang B Lc p lc:B lc c dng lc mt phn hay ton b cn bn c trong nc, ty thuc vo lp vt liu lc, tc lc Do vy, qua B Lc p lc, hu ht cc cn s b gi li bi 2 lp vt liu lc l than v ct thch anh. Nc thi t B Lc p lc chy sang B kh trng:B tip xc mang tnh cht l kh trng nc thi trc khi thi ra ngoi ngun tip nhn. Kh trng nc thi l nhm mc ch ph hu, trit b cc loi vi khun gy bnh nguy him hoc cha c hoc khng th kh b trong qu trnh x l nc thi.B tip xc c thit k vi dng chy ziczc qua tng ngn to iu kin thun li cho qu trnh xc tc gia Clo v nc thi.Clo l cht oxy ho mnh bt k dng no nu c chn lm cht kh trng.Khi cho Clo vo nc, phn ng din ra nh sau:Cl2 + H2O HOCl + HClHoc c th dng phng trnh phn ly:Cl2 + H2O H+ + OCl- + Cl-Axit hypoclorit (HOCl) c tc dng dit trng rt mnh. Khi cho Clo vo nc, cht dit trng s khuch tn qua v t bo vi sinh vt gy phn ng vi men bn trong ca t bo, lm ph hoi qu trnh trao i cht dn n vi sinh vt tiu dit.

1.3. Cng ngh x l nc thi c p dng ti nh my x l nc Bnh Hng Ha:Quy trnh x l nc thi nh my Bnh Hng Ha Thuyt minh quy trnh cng ngh:Nc thi t knh en trc khi khi chy n b phn lu vc trc nh my s c ngn li p trn (hay cn gi l p x l). Ti p ny nu lng nc chy trong knh en qu ln, mc nc dng cao s chy trn qua p i tip su vo trong dng knh en pha sau; cn trong iu kin mc nc bnh thng th lng nc trong knh en s b chn li p trn v nc s chy vo trong trm bm. Trc khi chy vo trong trm bm, dng nc thi s c chy qua song chn rc th c lp t pha trc nh my. Sau nc thi s c chy vo trong trm bm, ti trm bm c lp t 3 my bm truc vit c nhn vin vn hnh lun phin nha mi t 2 my( mi bm co cng sut 0,176 m3/h) , nu chay 2 bm se x ly c 60% lng nc thai cau knh en, con nu hoat ng ca 3 bm se x ly c ti 80% lng nc thai cua knh en. ng thi vic x dung bm truc vit con giup giam thiu lng rac thai chay vao trong cac cng trinh x ly. Nc thi sau khi c bm vo trm x l chng s c a vao mng lng cat, trong mng lng cat co b tri mt song chn rac tinh giup loai bo nhng phn rac nho hn con cha trong dong nc thai. Nc chay vao mng lng cat c lng xung (mng lng cat co 2 ngn song song nhau nhng nu chay 2 bm thi nhn vin chi cho nc chay mt ngn, con nu chay 3 bm thi se cho vn hanh 2 ngn song song vi nhau) . Cat c loai khoi mng bng 2 bm hut cat c t trn cu cng tac, cu cng tac se duy chuyn theo chiu dai knh va cat c hut ra theo khi va nh h thng ng va may hut khi c lp t trn cu cng tac, hn hp khi nay se c thai vao mang t b bn knh lng cat,sau o cat se c phi va c loai bo bng thit bi xon cat.Nc sau khi qua mng lng cat se c a vao trong h suc khi A1 gm 2 ngn, mi ngn co 4 may suc khi ( 2 may hoat ng, 2 may d phong lun phin nhau tranh cac may qua tai dn n tinh trang hong hoc), cng sut cua mi may la 37KW . H suc khi A2 vn hanh ni tip vi h suc khi A1. Trong thi gian cao im (3 may bm cung hoat ng) thi h suc khi A1 va A2 se hoat ng song song vi nhau, nc t h A1 c chay vao h A2 thng qua mt mang mo vit.Nc t h suc khi c a vao h thu (p tran mo vit) a sang h lng. Trong h thu co phay chn nc iu chinh thi gian lu nc trong h.Nc qua h thu t h suc khi chay vao h lng S1 va S2, hai h lng nay chay song sog vi nhau. Muc ich cua h lng la lng bng bun cha trong nc thai.T h lng, nc c dn vao h hoan thin gm 2 bn( mi bn 3 b). Muc ich cua h hoan thin la tip tuc giam nng COD,BOD co trong nc va dit coliform,ecoli bng anh sang mt tri. Cui cung nc c dn ra mt mang thu chung xa tr lai lu vc knh en.2. Mt s cng ngh x l nc thi tin tin:2.1. Cng ngh Actiflo:Actiflol mt h thng hp khi nh gn, h thng nyhot ng nh nhng ht ct rt nh (ActisandTM)lm ht nhn to nn cc bng bn nng. ActisandTMvi din tch b mt cao gip gia tng hiu sut ca qu trnh to bng, ng thi hot ng nh l mt cht m gip cho qu trnh lng trng lc din ra nhanh chng.

2.2. Cng ngh AnoxKaldnes TM MBBR:Cng ngh AnoxKaldnesMBBR da trn nguyn lmng sinh hc c cy trn cc gi thbng nha l lng trong b phn ng. Cng ngh ny pht huy li th cabn hot tnhv cccng ngh mng sinh hc khc(v d nh biofilters, biorotors) m khng b nh hng bi nhc im ca cc cng ngh ny.

2.3. Cng ngh Byostyr TM:c thit k bi Veolia Water Solutions & Technologies, Biostyrlcng ngh lc sinh hcdn u th trng vi hn 25 nm kinh nghim v hn 160 cng trnh ang vn hnh trn ton th gii.2.4. Cng ngh Ecodisk TM:Ecodisk l gii php l tng cho cckhu th nh,khch snv cca im du lch.Cc a c t chm mt phn trong nc v khi quay, mng sinh hc pha trn mt nc s hp thu kh -xy v khi chm li dc nc, chng s n cc cht hu c nh mt ngun thc phm.

2.5. Cng ngh hydrotech Discfilter TM:Hydrotech Discfilter, da lc bao gmcc mng vi c bit kh cc cht rn rt nh v thu hi cc cht c gi tr, l qu trnh x l bc ba - s dng vi lc - chonc u ra vi c c thp v nng cht rn l lng thp.

CHNG IV: KT LUN

Qua bo bo co vi chuyn : Cng ngh x l nc thi chng em hiu c s cn thit ca vic lm sch nc thi. Nc thi trong sn xut v sinh hot c rt nhiu thnh phn d bn, c hi ng thi c nh hng trm trng n sc khe con ngi cng nh l cnh quang mi trng xung quanh.Chnh v th, ngy cng c nhiu nhng cng ngh mi c to ra v c nng cp ci tin hiu qu x l nc thi ng thi tit kim chi ph p dng cho cng ngh. Th nhng vic p dng cng ngh x l nc thi vn cha , chng ta bn phn l mt ngi cn dn Vit Nam,chng ta phi c thc bo v mi trng xung quanh, bo v ci ti p ca t nc mnh, v cng chnh l vic m bo mt cuc sng ti p cho con em chng ta tng lai.

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Nguyn Th Hng Giang - MT1301Page 16