DA Xu Ly Nuoc Thai Nha May Bia2

8/3/2019 DA Xu Ly Nuoc Thai Nha May Bia2

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CHNG I TNG QUAN

1.1 Gii thiu

Bia l nc gi khc c t lu i 7000 nm trc cng nguyn c ghi chp

v sn xut bia. Hin nay nhu cu bia trn th gii cng nh Vit Nam rt ln v bial loi nc ung mt, b, c cn thp, c mn xp, c hng v c trng ca

hoa hoa houblon v cc sn phm trong qu trnh ln men to ra. c bit 2CO bo

ha trong bia c tc dng lm gim nhanh cn kht ca ngi ung, nh nhng u

im ny m bia c s dng rng ri hu ht cc nc trn th gii v sn lng

ngy cng tng.

Ngnh cng nghip sn xut bia Vit Nam c lch s hn 100 nm. Xng sn

xut bia u tin c t tn l xng sn xut bia Ch Ln, do mt ngi Php tn

l Victor Larue m vo nm 1875, l tin thn ca nh my bia Si Gn. min Bc,

vo nm 1889, mt ngi Php tn l Hommel m xng bia lng i Yn, Ngc

H, sau ny tr thnh nh my bia H Ni, nay tr thnh Tng cng ty Bia Ru

Nc gii kht H Ni. Trong qu trnh hnh thnh v pht trin ngnh sn xut bia

t mc tng trng cao vo nhng nm ca thi k m ca. Cng vi qu trnh hi

nhp, ngnh sn xut bia pht tirn v quy m v trnh cng ngh, tr thnh mtngnh cng nghip c th mnh khi Vit Nam gia nhp t chc WTO.Vic u t xy

dng cc nh my bia c trin khai mnh m t nhng nm 1990 tr li y.

Vit Nam cng vi s pht trin ca nn kinh t dn n thu nhp ca ngi

dn ngy cng cao. Nhu cu s dng cc loi nc gii kht cng nh bia ngy cng

tng, trong nhng nm qua nh my bia c u t xy dng ngy cng nhiu bng

kinh ph nh nc, t nhn v nc ngoi, p ng c nhu cu ca ngi tiu dng.

Vi s xut hin ca nhiu nh my bia th cc loi cht thi ra trong qu trnh sn

xut cng khng ngng tng ln. Cng vi nc thi sinh hot v nc thi ca cc

ngnh cng nghip khc gy gy ra s nhim nng n i vi mi trng v ngy

cng tr thnh vn cp bch. V vy vic nghin cu, thit k ra h thng x l

nc thi trong ngnh cng nghip sn xut bia l mt yu cu cp thit cho vic bo

v mi trng cng vi cc hot ng mang tnh thit thc i vi mi trng s m

bo cho s pht trin bn vng ca x hi loi ngi v cc loi sinh vt sng trn

hnh tinh chng ta.


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1.2. Qui trnh sn xut bia:

Cc cng on chnh ca cng nghip sn xut bia bao gm:

- Chun b nguyn liu: Malt i mch v nguyn liu thay th (go, la m, ng)

c lm sch ri a vo xoay, nghin t tng b mt hot ng ca enzym vgim thi gian nu.

- Lc dch ng thu nc nha trong v loi b malt. Qu trnh gm hai

bc:

Bc 1: Lc hn hp dch ng thu nc nha u;

Bc 2: Dng nc nng ra b thu nc nha cui v tch b malt.

- Nu vi hoa houblon to ra hng v cho bia, sau nc nha c qua

thit b tch b hoa.

- Lm lnh: Nc nha t ni nu c nhit xp x 100oC c lm lnh ti

nhit thch hp ca qu trnh ln men, nhit vo khong 10 16oC v qua hai

giai on. Giai on 1 dng nc lnh h nhit xung khong 60oC v giai on 2

dng tc nhn lnh glycol h nhit xung cn chng 14oC.

- Ln men chnh v ln men ph: y l cc qu trnh quan trng trong sn xut

bia. Qu trnh ln men nh tc dng ca men ging chuyn ho ng thnh alcoletylic v kh cacbonic:

+ 22

menln

612622 COOHHCOHC

Nhit duy tr trong giai on ln men chnh (6 n 10 ngy) t 8 n 10 oC. Sau

tip tc thc hin giai on ln men ph bng cch h nhit ca bia non xung 1

n 3oC v p sut 0,5 n 1 at trong thi gian 14 ngy cho bia hi v 21 ngy cho bia

ng chai, lon. Qu trnh ln men ph din ra chm v thi gian di gip cho cc cn

lng, lm trong bia v bo ho CO2, lm tng cht lng v bn ca bia. Nm men

tch ra, mt phn c phc hi lm men ging, mt phn thi c th lm thc n gia

sc. H nhit ca bia non thc hin giai on ln men ph c th dng tc nhn

lm lnh glycol.

- Lc bia nhm loi b tp cht khng tan nh nm men, protein, houblon lm

cho bia trong hn trn my lc khung bn vi cht tr lc l diatomit.

- Bo ho CO2 v chit chai: Trc khi chit chai, bia c bo ho CO2 bngkh CO2 thu c t qu trnh ln men cha trong bnh p sut. Cc dng c cha bia


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(chai, lon, kt) phi c ra, thanh trng m bo tiu chun v sinh, sau thc

hin qu trnh chit chai iu kin chn khng hn ch khc nhau m bo

cht lng trong thi gian bo hnh.

Trong cng ngh sn xut bia, nc c dng vo cc mc ch:- Lm nguyn liu pha trn theo t l nht nh nghin t malt v go (hay

la m) v b sung tip trong qu trnh nu - ng ha.

- Sn xut hi nc dng cho qu trnh nu ng ho, nu hoa, thanh trng.

- Mt lng nc ln dng cho qu trnh ra chai, lon, thit b my mc v sn

thao tc.


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Tch b

Nu hoa

Nc thi

Nu - ng ho

Thnh phm

Chun b nguyn liu

Chit chai, lon

Lm lnh

Bo ho CO2

Lc dch ng

Ln men ph

Ln men chnh

ng np

Lc bia

Thanh trng

Nc cp Nc cpcho sn xut

Hi nng

Ra chai

Xt

GoMalt

Hnh. Cng ngh v nc thi nh my bia


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1.3. Cc ngun pht sinh nc thi v c tnh nc thi cng nghip sn xut

bia.

Nc thi cng ngh sn xut bia bao gm:

- Nc lm lnh, nc ngng, y l ngun nc thi t hoc gn nh khng b nhim, c kh nng tun hon s dng li.

- Nc thi t b phn nu - ng ho, ch yu l nc v sinh thng nu, b

cha, sn nh nn cha b malt, tinh bt, b hoa, cc cht hu c,

- Nc thi t hm ln men l nc v sinh cc thit b ln men, thng cha,

ng ng, sn nh, xng, c cha b men v cht hu c.

- Nc thi ra chai, y cng l mt trong nhng dng thi c nhim ln

trong cng ngh sn xut bia. V nguyn l ng chai th phi c ra qua cc

bc: ra vi nc nng, ra bng dung dch kim long nng (1 -3 % NaOH), tip

l ra sch bn v nhn bn ngoi chai v cui cng l phun kim nng ra bn

trong v bn ngoi chai, sau ra sch bng nc nng v nc lnh. Do , dng

thi ca qu trnh ra chai c ph cao vo lm cho dng thi chung c gi tr pH

kim tnh.

Trong nc thi ra chia c hm lng ng v km l do s dng loi

nhn dn chia c in n bng cc loi thuc in c cha kim loi. Hin nay, loi nhn

dn chia c cha kim loi b cm s dng nhiu nc. Trong nc thi c tn ti

AOX l do trong qu trnh kh trng c dung cht kh l hp cht ca clo.

1.4 Thnh phn c trng ca ca nc thi

c trng ca nc thi nh my bia l c hm lng cc cht hu c protein v

cacbonate cao.

Nc thi lc b hm trong cng ngh:y l loi nc thi nhim kh mnh. Nc thi pht sinh t cng ngh lc

phn, nn chng b nhim bn bi cc cht hu c, cn b hm , cc vi sinh vt.

Nc thi lc dch ng:

Lng nc thi ny thng b nhim bn hu c, lng gluco trong nc ny

cng mc cao, l mi trng thun li cho s pht trin ca cc loi vi sinh vt.

Ngoi ra nc thi lc dch ng c c v mu kh cao.


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Nc thi ca cc thit b gii nhit c coi l sch nhng c nhit cao 40

45oC c th c mt lng du m nhng khng ng k.

Trong sn xut bia, cng ngh t thay i t nh my ny sang nh my khc,

s khc nhau c th ch l s dng phong php ln men chm hay ni. Nhng skhc nhau c bn l vn s dng nc cho qu trnh ra chai, lon, my mc thit

b, sn nh, s lng cng nhn s dng nc cho sinh hot iu dn n ti

lng nc thi v hm lng cc cht nhm ca cc nh my bia rt khc nhau.

Kt qu phn tch thnh phn nc thi mt s nh my bia

Thng s n v Nh my I Nh my II Nh my IIIpH 5,7 11,7

BOD5 mg/l 185 2400 775 1622COD mg/l 310 3500 1220 2944Nito tng mg/l 48 348 19,2Photpho tng mg/l 1,4 9,09 7,6 -Cht khng tan mg/l 158 1530 - -Ti lng

nc thi

m3/1000 lt bia 3,2 - -

Ti trng kgBOD5/1000

lt bia

35 - -

Theo Trn Vn Nhn, Ng Th Nga, Gio trnh cng ngh x l nc thi, bng 3.34,

trang 314

1.5 Cc phng php x l nc thi

1.5.1. Phng php c hc:

1.5.1.1. Nguyn tc chung:

Nc thi c thnh phn ht sc phc tp. Trong nc thi khng ch cha cc

thnh phn ho hc ho tan, cc loi vi sinh vt, m cn cha cc cht khng ho tan.

Cc cht khng ho tan c th c kch thc nh v c th c kch thc ln. Ngi

ra da vo kch thc v t trng ca chng loi chng ra khi mi trng nc,

trc khi p dng cc phng php ho l hoc cc phng php sinh hc.

Cc vt cht c kch thc ln nh cnh cy, bao b cht do, giy, gi rch,

ct, si v c nhng git du, m. Ngoi ra, vt cht cn nm dng l lng hoc

dng huyn ph.


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Tu theo kch thc v tnh cht c trng ca tng loi vt cht m ngi ta

a ra nhng phng php thch hp loi chng ra khi mi trng nc. Nhng

phng php loi cc cht rn c kch thc ln v t trng ln trong nc c gi

chung l phng php c hc.Phng php x l c hc c th loi b c n 60% cc tp cht khng ho

tan c trong nc thi v gim 20% BOD. Cc cng trnh trong x l c hc bao gm:

- Song chn rc hoc li lc.

- B lng ct.

- B lng.

- iu ho lu lng dng chy.

- Qu trnh tuyn ni.

1.5.1.2. Song chn rc:

Song chn rc nhm chn gi cc cn bn c kch thc ln hay dng si:

giy, rau c, rc c gi chung l rc. Rc c chuyn ti my nghin nghin

nh, sau c chuyn ti b phn hy cn (b mtan). i vi cc tp cht < 5 mm

thng dng li chn rc. Cu to ca thanh chn rc gm cc thanh kim loi tit

din hnh ch nht, hnh trn hoc bu dc Song chn rc c chia lm 2 loi di

ng hoc c nh, c th thu gom rc bng th cng hoc c kh. Song chn rc c

t nghing mt gc 60 90 0 theo hng dng chy.

1.5.1.3. B tch du m

B tch du m thng c ng dng trong x l nc thi cng nghip c

cha du m, cc cht nh hn nc v cc dng cht ni khc. i vi nc thi sinh

hot, do hm lng du m v cc cht ni khng ln cho nn c th thc hin vic

tch chng ngay b lng t mt nh cc thanh gt thu hi du m, cht ni trn bmt b lng.

1.5.1.4. B lng ct

B lng ct dng tch cc cht bn v c c trng lng ring ln hn nhiu

so vi trng lng ring ca nc nh x than, ct ra khi nc thi. Thng

thng cn lng c ng knh ht khong 0,25 mm (tng ng ln thu lc l

24,5) chim 60% tng s cc ht cn c trong nc thi.


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Theo chiu dng chy, b lng c phn thnh: b lng ngang v b lng

ng.

Trong b lng ngang, dng nc chy theo phng ngang hoc vng qua b

vi vn tc ln nht Vmax = 0,3 m/s, vn tc nh nht Vmin = 0,15 m/s v thi gian lunc t 30 60 giy. i vi b lng ng, nc thi chuyn ng theo phng

thng ng t di ln vi vn tc nc dng t 3 3,7 m/s, vn tc nc chy trong

mng thu (xung quanh b) khong 0,4 m/s v thi gian lu nc trong b dao ng

trong khong 2 -3,5 pht.

Ct trong b lng c tp trung v h thu hoc mng thu ct di y, ly

ct ra khi b c th bng th cng (nu lng ct < 0,5 m 3/ngy m) hoc bng c

gii (nu lng ct > 0,5 m3/ngy m). Ct t b lng ct c a i phi kh sn

phi v ct kh thng c s dng li cho nhng mc ch xy dng.

1.5.1.5. B lng:

B lng lm nhim v tch cc cht l lng cn li trong nc thi (sau khi qua

b lng ct) c t trng ln hn hoc nh hn t trng ca nc di dng lng xung

y b hoc ni ln trn mt nc. Thng thng b lng c ba loi ch yu: b lng

ngang (nc chuyn ng theo phng ngang), b lng ng (nc chuyn ng theo

phng thng ng), v b lng ly tm (nc chuyn ng t tm ra xung quanh)

thng c dng hnh trn trn mt bng. Ngoi ra, cn mt s dng b lng khc nh

b lng nghing, b lng c thit k nhm tng cng hiu qu lng.

1.5.1.6. iu ho lu lng dng chy:

Trong qu trnh x l nc thi cn phi iu ho lng dng chy. Trong qu

trnh ny thc cht l thit lp h thng iu ho lu lng v nng cht nhimtrong nc thi nhm to iu kin tt nht cho cc cng trnh pha sau hot ng n

nh. B iu ho dng chy c th b tr trn dng chy hay b tr ngoi dng chy.

1.5.1.7. Qu trnh tuyn ni:

Tuyn ni l qu trnh tch cc cht dng rn hoc dng lng, phn tn khng

tan trong nc thi c khi lng ring nh, t trng nh hn nc khng th lng

bng trng lc hoc lng rt chm. Phng php tuyn ni c thc hin bng cch

trn ln cc ht kh nh v mn vo nc thi, khi cc ht kh s kt dnh vi cc


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ht ca nc thi v ko theo nhng ht vt cht ny theo bt kh ni ln b mt. Khi

ta c th d dng loi chng ra khi h thng bng thit b vt bt.

tng hiu sut to bt, ngi ta thng s dng cc cht to bt nh eresol,

phenol nhm gim nng lng b mt phn pha. Tu theo phng thc cp khng khvo nc, qu trnh tuyn ni bao gm cc dng sau:

Tuyn ni bng kh phn tn: Kh nn c thi trc tip vo b tuyn ni

to thnh cc bt kh c kch thc t 0,1 1 mm, gy xo trn hn hp kh - nc

cha cn. Cn tip xc vi bt kh, kt dnh v ni ln b mt.

Tuyn ni chn khng: bo ho khng kh p sut kh quyn, sau thot kh

ra khi nc p sut chn khng. H thng ny t s dng trong thc t v kh vn

hnh v chi ph cao.

Tuyn ni bng kh ho tan: Sc khng kh vo nc p sut cao (2-4 at), sau

gim p gii phng kh. Khng kh thot ra s to thnh bt kh c kch thc 20 -

100m.

1.5.2. X l sinh hc

Qu trnh x l nc thi bng phng php sinh hc l qu trnh nhm phn

hy cc vt cht hu c dng ha tan, dng keo v dng phn tn nh trong ncthi nh vo s hot ng ca cc vi sinh vt. Qu trnh ny xy ra trong iu kin

hiu kh hoc k kh tng ng vi hai tn gi thng dng l: qua trnh x l sinh hc

hiu kh v qu trnh x l sinh hc k kh (ym kh).

Qu trnh x l sinh hc k kh thng c ng dng x l s b cc loi

nc thi c hm lng BOD5 cao (>1000 mg/l), lm gim ti trng hu c v to

iu kin thun li cho cc qu trnh x l hiu kh din ra c hiu qu. X l sinh hc

k kh cn c p dng x l cc loi bn, cn (cn ti t b lng t mt, bn

hot tnh sua khi nn ) trong trm x l nc thi th v mt s ngnh cng

nghip.

Qu trnh x l sinh hc hiu kh c ng dng c hiu qu cao i vi nc thi

c hm lng BOD5 thp nh nc thi sinh hot sau x l c hc v nc thi ca

cc ngnh cng nghip b nhim hu c mc thp (BOD5 < 1000 mg/l). Ty

theo cch cung cp oxy m qu trnh x l sinh hc hiu kh c chia lm hai loi:


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- X l sinh hc hiu kh trong iu kin t nhin (oxy c cung cp t khng

kh t nhin do quang hp ca to v thc vt nc) vi cc cng trnh tng ng

nh: cnh ng ti, cnh ng lc, h sinh hc, t ngp nc

- X l sinh hc hiu kh trong iu kin nhn to (oxy c cung cp bi ccthit b sc kh cng bc, thit b khuy trn c gii) vi cc qu trnh v cng

trnh tng ng nh sau:

Qu trnh vi sinh vt l lng (qa trnh bn hot tnh):

B bn hot tnh thi kh (Aerotank)

Mng oxy ha

H sinh hc

Qu trnh vi sinh vt dnh bm (Qu trnh mng vi sinh vt):

B lc sinh hc nh git (Biophin)

B lc sinh hc cao ti

Thp lc sinh hc

B lc sinh hc tip xc dng a quay (RBC): cng trnh ny

cho php x l nit v photpho trong nc thi (x l bc cao).

Qu trnh vi sinh vt kt hp: b sinh hc hiu kh tip xc (c cu to

v nguyn l hot ng ging nh b Aerotank nhng bn trong b c trang b thm

cc vt liu tip xc lm gi th cho cc vi sinh vt dnh bm)

1.5.3. X l ha hc:

Bn cht ca qu trnh x l nc thi bng phng php ho l l p dng cc

qu trnh vt l v ho hc a vo nc thi cht phn ng no gy tc ng

vi cc tp cht bn, bin i ho hc, to thnh cc cht khc di dng cn hoccht ho tan nhng khng c hi hoc gy nhim mi trng. Giai on x l ho

l c th l giai on x l c lp hoc x l cng vi cc phng php c hc, ho

hc, sinh hc trong cng ngh x l nc thi hon chnh.

Nhng phng php ho l thng c p dng x l nc thi l : keo t,

ng t, hp ph, trao i ion, thm lc ngc v siu lc

1.5.3.1.Phng php keo t v ng t


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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 c hiu qu bng phng php

lng, cn tng kch thc ca chng nh s tc ng tng h gia cc ht phn tnlin kt thnh tp hp cc ht, nhm tng vn tc lng ca chng. Vic kh cc ht

keo rn bng lng trng lng i hi trc ht cn trung ha in tch ca chng, th

n l lin kt chng vi nhau. Qu trnh trung ho in tch thng c gi l qu

trnh ng t (coagulation), cn qu trnh to thnh cc bng ln hn t cc ht nh

gi l qu trnh keo t (flocculation).

1.5.3.2.Hp ph

Phng php hp ph c dng rng ri lm sch trit nc thi khi

cc cht hu c ho tan sau khi x l sinh hc cng nh x l cc b khi nc thi c

cha mt hm lng rt nh cc cht . Nhng cht ny khng phn hu bng con

ng sinh hc v thng c c tnh cao. Nu cc cht cn kh b hp ph tt v chi

ph ring cho lng cht hp ph khng ln th vic ng dng phng php ny l

hp l hn c.

Cc cht hp ph thng c s dng nh: than hot tnh, cc cht tng hp

v cht thi ca vi ngnh sn xut c dng lm cht hp ph (tro, x, mt ca ).

Cht hp ph v c nh t st, silicagen, keo nhm v cc cht hydroxit kim loi t

c s dng v nng lng tng tc ca chng vi cc phn t nc ln. Cht hp

ph ph bin nht l than hot tnh, nhng chng cn c cc tnh cht xc nh nh :

tng tc yu vi cc phn t nc v mnh vi cc cht hu c, c l xp th c

th hp ph cc phn t hu c ln v phc tp, c kh nng phc hi. Ngoi ra, than

phi bn vi nc v thm nc nhanh. Quan trng l than phi c hot tnh xc tcthp i vi phn ng oxy ha bi v mt s cht hu c trong nc thi c kh nng

b oxy ho v b ho nha. Cc cht ho nha bt kn l xp ca than v cn tr vic

ti sinh n nhit thp.

I.3.3. Phng php trao i ion

Trao i ion l mt qu trnh trong cc ion trn b mt ca cht rn trao i

vi ion c cng in tch trong dung dch khi tip xc vi nhau. Cc cht ny gi l

cc ionit (cht trao i ion), chng hon ton khng tan trong nc.


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Cc cht c kh nng ht cc ion dng t dung dch in ly gi l cationit,

nhng cht ny mang tnh axit. Cc cht c kh nng ht cc ion m gi l anionit v

chng mang tnh kim. Nu nh cc ionit no trao i c cation v anion gi l cc

ionit lng tnh. Phng php trao i ion thng c ng dng loi ra khi nccc kim loi nh: Zn, Cu, Cr, Ni, Pb, Hg, M , cc hp cht ca Asen, photpho,

Cyanua v cc cht phng x.

Cc cht trao i ion l cc cht v c hoc hu c c ngun gc t nhin hay

tng hp nhn to. Cc cht trao i ion v c t nhin gm c cc zeolit, kim loi

khong cht, t st, fenspat, cht mica khc nhau v c tng hp gm silicagen,

pecmutit (cht lm mm nc ), cc oxyt kh tan v hydroxyt ca mt s kim loi nh

nhm, crm, ziriconi Cc cht trao i ion hu c c ngun gc t nhin gm axit

humic v than chng mang tnh axit, cc cht c ngun gc tng hp l cc nha

c b mt ring ln l nhng hp cht cao phn t.

1.5.3.4.Cc qu trnh tch bng mng

Mng c nh ngha l mt pha ng vai tr ngn cch gia cc pha khc

nhau .Vic ng dng mng tch cc cht ph thuc vo thm ca cc hp cht

qua mng. Ngi ta dng cc k thut nh: in thm tch, thm thu ngc, siu

lc v cc qu trnh tng t khc.

Thm thu ngc v siu lc l qu trnh lc dung dch qua mng bn thm

thu, di p sut cao hn p sut thm lc. Mng lc cho cc phn t dung mi i

qua v gi li cc cht ho tan. S khc bit gia hai qu trnh l ch siu lc

thng c s dng tch dung dch c khi lng phn t trn 500 v c p sut

thm thu nh (v d nh cc vi khun, tinh bt, protein, t st ). Cn thm thu

ngc thng c s dng kh cc vt liu c khi lng phn t thp v c psut cao.

1.5.3.5. Phng php in ho

Mc ch ca phng php ny l x l cc tp cht tan v phn tn trong nc

thi, c th p dng trong qu trnh oxy ho dng cc, kh m cc, ng t in v

in thm tch. Tt c cc qu trnh ny u xy ra trn cc in cc khi cho dng in

1 chiu i qua nc thi.

Nhc im ln ca phng php ny l tiu hao in nng ln


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CHNG II XUT QUY TRNH CNG NGH

2.1 Thng s u vo v ch tiu u ra ca nc thi

Thng s u vo:pH = 6,5

BOD5 = 1000 mg/l

COD = 1500 mg/l

SS = 400 mg/l

Ch tiu u ra theo QCVN :24/2009 BTNMT, loi B

pH = 6 -9

BOD5 = 50 mg/l

COD = 100 mg/l

SS = 100 mg/l

2.2 Cc ch tiu nh hng n vic la chn quy trnh cng ngh

Nhu cu oxy sinh ha BOD: l lng oxy cn thit cho vi khun sng v hot ng

oxy ha cc cht hu c c trong nc thi. Nhu cu oxy sinh ha l ch tiu rt quan

trng th hin mc nhim bn ca nc thi bi cc cht hu c._ Ch tiu BOD c dng rng ri :

+ Xc nh gn ng lng oxy cn thit n nh sinh hc cc cht hu c

c trong nc thi.

+ Xc nh kch thc thit b x l.

+ Xc nh hiu sut ca mt s qu trnh.

+ Xc nh s chp thun tun theo nhng quy nh cho php thi cht thi.

Nhu cu oxy ha hc COD : l lng oxy cn thit oxy ha cc cht hu c v mt

phn cc cht hu c c trong nc thi. Ch tiu BOD khng phn nh ht kh nng

oxy ha cc cht hu c kh b oxy ha v cc cht v c c th b oxy ha trong

nc thi, nht l nc thi cng nghip. Do vy, ch tiu COD c gi tr cao hn gi

tr BOD.

T s COD/BOD cng nh th x l sinh hc cng d hay ni cch khc t s

BOD/COD cng gn 1 th nc b nhim hu c cng ln.


14/45

Hm lng cht rn l lngl ch tiu tnh ton cc b lng v xc nh s lng

cn lng. S tn ti ca cn lng l lng trong cng trnh x l sinh hc s nh hng

rt nhiu n hiu sut ca qu trnh x l, do nc thi cn phi c loi b cn

trc khi i vo b x l sinh hc (i vi b aerotank th lng cn l lng trc khivo b ny khng vt qu 150mg/l; vi b UASB th lng cn c th ln ti

3000mg/l).

Tr s pH: cho bit nc thi c tnh trung ha, tnh acid hay tnh kim. Qu trnh x

l nc thi bng phng php sinh hc rt nhy cm vii s giao ng ca tr s pH.

Qu trnh x l hiu kh i hi gi tr pH trong khong 6,5 n 8,5 khong ti u 6,8

n 7,4; qu trnh x l k kh gi tr pH trong khong 6,6 n 7,6.

Ngoi cc ch tiu trn, cc ch tiu v oxy ha tan DO; cc kim loi nng; cht

dinh dng nh nit, photpho.nh hng rt nhiu n vic la chn quy trnh cng

ngh x l nc thi m bo hiu qu x l.

2.3 C s la chn quy trnh cng ngh

Khi la chn mt cng ngh x l nc thi cn phi cn c vo cc yu cu sau:

_ Lu lng, thnh phn v tnh cht ca nc thi.

_ Din tch mt bng hin c, cng nh cc iu kin m nh my c th chpnhn.

_ Tiu chun u ra ca dng thi.

_ c tnh ca ngun tip nhn.

_ Kinh ph u t ban u v chi ph vn hnh.

_ m bo kh nng x l khi nh my m rng sn xut.

Ti Vit Nam cc nh my bia hu nh khng a vo cc khu cng nghip m

thng c nh my gn khu dn cdo vy nh my thng c din tch mt bng

nh. Trong quy trnh x l nc thi , cc cng trnh x l cn phi c din tch va

phi ph hp vi mt bng hin c ca nh my.

2.4 Quy trnh cng ngh x l nc thi nh my bia

2.4.1 S quy trnh cng ngh


15/45

2.4.2 Thuyt minh quy trnh cng ngh:

- Nc thi sn xut bia c thu gom qua song chn rc (SCR) vo b tip nhn.SCR c nhim v loi b cc tp cht c kch thc ln nh bao ni lng, ng ht,

nm ln trong nc thi.

- Nc thi t b tip nhn c bm ln b iu ha sau khi qua li lc. Li lc l

thit b lc tinh dng loi b phn rc mn. B iu ho gi chc nng iu ho

nc thi v lu lng v nng .

- Nc thi tip tc c dn vo b lc sinh hc k kh (UASB) nhm phn hy cc

cht hu c phc tp thnh cc cht hu c n gin hn v chuyn ha chng thnh

Clo

My p bn

B nn bn

Nc thi SCR B tip nhn Li lc

B iu ha

B UASBB AerotankB lng t

II

B kh trng

Nc thiu ra

Bn tun hon

Bn d

Rc Bi chn lp

My nn kh Thi kh


16/45

CH4, CO2, H2S, Sau , Nc thi c a sang b lc sinh hc hiu kh. B lc

sinh hc hiu kh va c nhim v x l tip phn BOD5, COD cn li va lm gim

mi hi c trong nc thi.

- Sau khi x l b lc sinh hc hiu kh nc thi tip tc chy sang b lng 2

lng bn hot tnh. Lng bn ny c rt khi b lng bng h thng bm bn v

tun hon v b lc sinh hc hiu kh, bn d c dn v b nn bn.

- Nc thi t b lng 2 tip tc chy qua b kh trng nhm tiu dit vi trng v

mm bnh c trong nc thi. Sau khi ra khi b kh trng nc thi s t

QCVN:24/2009 BTNMT, loi B

2.4.3 Thuyt minh cc cng trnh n v2.4.3.1 Song chn rc

Song chc rc thng lm bng kim loi, t ca vo ca knh dn s gi li

nhng tp cht c kch thc ln bo v cc thit b x l nh bm, ng ng

Da vo khong cch ng ta chia song chn rc thnh hai loi:

_ Song chn rc th c khong cch gia cc thanh t 60 n 100 mm.

_ Song chn rc mn c khong cch gi cc thanh t 10 n 25 mm.

Chn song chn rc mn c khong cch gia cc thanh l 20 mm c t c nh,

nghing mt gc 60o t ca b tip nhn v c ly rc vo cui ngy.

2.4.3.2 B tip nhn

B tip nhn l ni tip nhn ngun nc thi trc khi i vo cc cng trnh

x l tip theo. B tip nhn thng c lm bng b tng hoc bng gch. Trong

quy trnh ny b tip nhn cn c tc dng iu ha lu lng nc thi.

2.4.3.3 Li lcNhim v ca li lc l gi li cac cht rn l lng c kch thc nh. Li

c kch thc l t 0,5 n 1mm. Trong nh my bia , cc mu tru, huyn ph b

tri ra trong qu trnh ra thng ln men, thng nu, nc lc b hm, s c gi li

nh h thng li lc c kch thc l 1mm. Cc vt thi c ly ra khi b mt li

bng h thng co.

2.4.3.4 B iu ha


17/45

c dng duy tr lu lng dng thi vo gn nh khng i, quan trng l iu

chnh pH n gi tr thch hpcho qu trnh x l sinh hc. Trong b c h thng

thit b khuy trn hoc h thng thi kh m bo ha tan v lm u nng cht

bn trong ton th tch b v khng cho lng cn trong b, pha long nng cc chtc hi nu c. Ngoi ra cn c thit b thu gom v x bt, vng ni. Ti b iu ha

c my nh lng acid cn phi thm vo b m bo pH t 6,6 7,6 trc khi

a vo b UASB.

2.4.3.5 B UASB

_ Qu trnh x l nc thi bng phng php sinh hc k kh l mt qu trnh

pht trin tng i gn y trong lnh vc cng ngh mi trng. u im

ca phng php ny l: t tiu hao nng lng trong qu trnh hot ng, gi

thnh vn hnh thp v t sn sinh ra nng lng c th thu hi s dng di

dng biogas. Thm vo , cc h thng x l k kh sn sinh t bn tha hn

so vi h thng hiu kh, trung bnh khong t 0,03 0,15 g bn VSS trn 1g

BOD c kh.Hn na, s duy tr sinh khi trong cc h thng x l k kh

vi t l cao cho php vn hnh h thng x l cc ti trng hu c cao v do

lm gim ng k khi tch ca cc cng trnh._ Ti trong hu c thch hp trn cc thit b UASB x l nc thi cng nghip

khong t 8 n 15 kg COD/m3.ngy. Hiu qu x l COD tng i cao,

trung bnh vo khong 43 78% trong a s cc trng hp. iu ny cho thy

rng x l k kh c kh nng ng dng rng ri gim thiu cc cht hu c

d phn hu sinh hc trong nc thi cng nghip ca nhiu loi hnh sn xut.

_ Ti y din ra qu trnh phn hy cc cht hu c, v c c trong nc thi

khi khng c oxy. Nc thi c a trc tip vo t pha di y b v

c phn phi u , sau chy ngc ln, xuyn qua lp bn sinh hc

dng ht nh v cc cht hu c, v c b tiu th y. Qu trnh chuyn ha

cc cht bn trong nc thi bng vi sinh vt ym kh xy ra theo 3 giai on:

+ Giai on 1: mt nhm vi sinh vt t nhin c trong nc thi thy phn

cc hp cht hu c phc tp v lipit thnh cc cht hu c n gin c

trng lng nh nh monosacarit, amino acid to ra ngun thc n vnng lng cho vi sinh hot ng.


18/45

+ Giai on 2: nhm vi khun to men acid bin i cc hp cht hu c

n gin thnh cc acid hu c thng l acid acetic, acid butyric, acid

propionic. giai on ny pH ca dung dch gim xung.

+ Giai on 3: cc vi khun to mtan chuyn ha hydro v acid aceticthnh kh mtan v cacbonic, pH ca mi trng tng ln.

2.4.3.6 B aerotank

Sau khi nc thi c x l b UASB th nng cht hu c gim xung

s c x l tip b aerotank. Khi trong b cc cht l lng ng vai tr 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 cc vi sinh vt sng

khc. Vi khun v cc vi sinh vt sng dng cht n (BOD) v cht dinh dng (N, P)

lm thc n chuyn ha chng thnh cc cht tr khng ha tan v thnh cc t bo

mi. Qu trnh chuyn ha c thc hin xen k v ni tip nhau. B aerotank c

cung cp kh lin tc vo b trn u, gi cho bn hot tnh trng thi l lng

trong nc thi v cung cp lng oxy cn thit cho cc phn ng sinh ha din ra

trong b p ng mc x l yu cu.2.4.3.7 B lng II: nhim v ca b lng l lng bn hot tnh qua x l b

Aeroten hay mng vi sinh cht t b Aeroten v lng bn d b UASB

2.4.3.8 B kh trng

Nhm mc ch loi tr cc vi sinh vt gy bnh cha c hoc khng th

tiu dit trong cc qu trnh x l trc . Trong nc thi ca ngnh sn xutbia th

cc loi nm, vi sinh vt c rt nhiu.

tiu dit hon ton cc vi sinh vt gy bnh, ta c th kh trng bng

phng php khc nhau nh: clo ha, ozon ha, tia cc tm UVThng thng

phng php clo ha c s dng rng ri hn.

Phn bn c sau khi phn hy nh k c bm sang b nn bn. Bn d t

b aerotank, UASB v bn t b lng 2 ca qu trnh bn hot tnh cng c

bm sang b nn bn. Bn t cc qu trnh trn sau khi nn c bm sang my

p bn p thnh bnh bn. Bnh bn c th em lm phn bn hoc chn lp hp

v sinh.


19/45

CHNG III TNH TON THIT K

Thng s tnh ton

Lu lng nc thi: Q = 1800 m3/ ngy m

Q = 0,021 m3/spH = 6,5

BOD5 = 1000 mg/l

COD = 1500 mg/l

SS = 400 mg/l

3.1 Song chn rc

Tng din tch khe h (A) ca song chn rc

maxQA =V

Qmax: lu lng cc i ca nc thi , m3/s

V: tc nc chy cc i qua song chn rc (0,4-0,8 m/s); chn v = 0,7 m/s

0,021A =

0,7= 0,03 m2

Tng chiu rng cc khe ca song chn rc

AW =d

d: Chiu su lp nc song chn rc, chn d = 0,2 m

A: tng din tch khe h ca song chn rc, m2

W: tng chiu rng ca cc khe h,m

0,03W =

0,2= 0,15 m

Chn chiu rng ca khe bng 20 mmS khe h ca song chn rc

Wn =

0,02=

0,150,02

= 8

S dng 9 thanh c chiu rng bng 10 mm v chiu dy 10 mm

Chiu rng ca bung t song chn rc

B = W + chiu rng thanh s thanh

B = 0,15 + 0,01 9 = 0,24 m


20/45

Chiu cao ca song chn rc

1 o

0,2h =

sin60= 0,23 m

Kim tra li vn tc dng chy ti v tr m rng trc song chn ng vi lu

lng nc thi nh nht nhm trnh s lng cn ti . Vn tc ny phi > 0,4 m/s.

max 0,021 0,44 / 0,4 /. 0,24 0,2

kt

QV m s m s

B d= = = >

Tn tht p lc qua song chn rc:2 2 2 21 1 0,7 0,44

0,022 220,7 2 0,7 2 9,81

kts

V Vh m mm

g

= = = =

Chiu cao tng cng ca song chn rc:1 0,23 0,022 0,5 0,752( )s bvH h h h m= + + = + + =

3.2Tnh ton b iu ha

3.2.1 Tnh ton b iu ho:

Chn thi gian lu nc thi trong b l 8 gi

Th tch b iu ho:

3

dh

1800=Qt= 8= 600 m

24V

Th tch thc t ca b iu ho: Vth = 1,3 . Vdh = 1,3 600 =780 m3

(Theo TCXD 51:2008, cng thc 7-8, trang 42)

Chn chiu su mc nc l Hdh = 4. Din tch ca b iu ho:

2780 1954

dh

dh

VS m

H= = =

Chiu cao xy dng ca b iu ho: Hxd = Hdh + Hbv = 4 + 0,5 = 4,5m

Xy dng 2 n nguyn hnh ch nht.

Kch thc ca mi n nguyn l :

dh dh xdL B H =13m7,5m4,5m

3.2.2 Tnh ton h thng cp kh cho mi b iu ho

Lu lng khng kh cn cung cp cho b iu ha3

khiL = Q a = 75 3 = 225 m/h

Trong :


21/45

a:Cng thi kh , a = 2 - 4 m3 kh/m3 nc thi. Chn a = 3 m3/m3 nc

thi

Q: lu lng nc thi, m3/h

Chn h thng ng cp kh bng thp c c l, c 5 ng t dc theo chiu dica b iu ho, mi ng cch nhau 1,5 m.

Lu lng kh trong mi ng:

3225 45 /5 5khi

ong

Lq m h= = =

ng knh ng dn kh:

ongong

ong

4q 445d = = = 0,04 m = 40 mm

v 3600 103600

Trong ongv l vn tc kh trong ng, ongv = (10 25) 40 m/s. (iu 6.40

TCXD 51:2008). Chn ongv =10m/s

Chn ng dn kh c =40 mm. Cc ng c khoan l, ng knh l d l =

4mm nm mt di ng. ng t trn cc gi cao 6 10 cm so vi y v

vn tc kh qua l chn vl = 12m/s.

2 2

-3 3 3lo lolo v d 12 0,004q = = =0,15110 m /s = 0,543m /h4 4

S l trn mi ng:ong

lo

q 45N= = =82,9

q 0,543l

S l trn 1m chiu di ng:

82,96,4

13 13

Nn= = = l

Chn n = 7 l/m ng.

Vy tng s l trn 1 ng

N = n 13 = 7 13 = 91 l

3.3Tnh ton b UASB

Nc thi sau khi x l b UASB cn m bo nng cc cht nhim thun li

cho vic x l b aerotank

Gi s cc thng s COD, BOD, SS sau khi qua cc cng trnh x l trc b UASB

gim i mt lng nh sau:COD gim 17% (ban u 1500mg/l)


22/45

BOD gim 20% (ban u 1000mg/l)

SS gim 28% (ban u 400 mg/l)

Vy cc thng s u vo ca b UASB:

pH = 6,6 7,6COD = 1245 mg/l

BOD = 800 mg/l

SS = 288 mg/l

3.3.1 Kch thc b

Chn hiu qu x l COD l 65% v BOD5 l 70% ta c lng COD cn kh trong 1

ngy:

bdCOD

Q COD 65G =

100

31800 1245 10 65=

100

= 1456,7kgCOD/ ng

Lng BOD c kh trong 1 ngy

bdBOD

Q BOD 70G =

100

31800 800 10 70=

100

= 1008 kgBOD/ng

Chn ti trng x l cht hu c trong b UASB l L = 8 kgCOD/m 3ng ( Theo

PSG.TS Nguyn Vn Sc, Gio trnh Cng ngh x l nc thi, bng 7.5, trang 205)

Th tch phn phn ng

1456,7V =

L 8

G= =182,1 m3

Din tch b mt b

A =v

Q

Trong

Q : lu lng nc thi m3/hv: vn tc dng hng ln, gi cho lp bn trng thi l lng, tc nc

dng ln trong b phi gi trong khong 0,6 0,9 m/h. chn v = 0,9 m/h

1800A =

0,9 24= 83,3 m2

Chn A = 84 m2

Xy dng 2 n nguyn. Vy din tch ca mi n nguyn l F = 42 m2

Chiu cao phn phn ng


23/45

1

V 182,1H = = =4,34 m

F 42

Chn H1 = 4,5 m

Chn chiu cao vng lng H2 =1,5m

Chiu cao bo v H3 =0,5m

Chiu cao tng cng b UASB l:

H = H1 + H2 + H3 = 4,5 + 1,5 + 0,5 = 6,5 m

Vy kch thc xy dng mi b UASB

Chiu di L = 7m

Chiu rng B = 6m

Chiu cao H = 6,5 mTh tch thc ca mi b khi xy dng

Vt = 7 6 6,5 = 273 m3

Thi gian lu nc trong b

tV 273 24

T= = = 7,28 hq 900

Vi q lu lng nc thi ca mi n nguyn, m3/h

3.3.2 Tnh ngn lng

Trong mi n nguyn b tr 4 tm chn kh v 2 tm hng dng. Nc trc

khi i vo ngn lng s c tch kh ra khi hn hp nc thi bng cc tm

tch kh t nghing so vi phng ngang mt gc t 45 60o. Chn gc

nghing gia cc tm kh v phng ngang l 60o. Cc tm ny t song song

nhau.

Tng chiu cao ton b ngng lng Hnglng (k c chiu cao vng lng) v chiu

cao d tr chim trn 30% tng chiu cao b. Trong b ta chia thnh 2 ngn

lng

Ta c:

( )3nglang0

0 0

3nglang

3nglang

H +Htg60 =

L4

Ltg60 7tg60H +H = = = 3,03m

4 4H =3,03-H =3,03-0,5= 2,53m


24/45

b2

tam chan 1

r

y1 b

1

tam chan 2

x1

x2

h1

Hnglang

Kim tra li

( )3nglangbe

H H 3,03100% 100% 46,6%

H 6,5

+ = = >30%

Vy chiu cao xc nh l thch hp

Thi gian lu nc trong ngn lng

nglangnglang7L BH 62,53V 2 2t= 24=2 24=2 24=2,83h

q/2 q 900

3.3.3 Tnh ton tm chn kh

Chn khe h gia cc tm chn kh v gia tm chn kh vi tm hng dng

l nh nhau.

Tng din tch ca cc khe h ny chim 15 20% tng din tch n nguyn.

Chn Skhe = 0,16S

Hnh Tm chn kh v hng dng UASB

Din tch mt khe h

khe

0,16S 0,16 42S =

n 8

= = 0,84 m2

Vi n l s khe

B rng mt khe h


25/45

kheS 0,84b =B 6

= = 0,14m = 140 mm

Tnh ton cc tm chn

Tm chn 1

Chiu di l1 = R = 6m = 6000 mm

Chiu rng b1 = (Hnglng H2)/sin60o = (2,53 1,5)/sin60o = 1,19m = 1190 mm

Chiu cao 0 01 1 sin60 1190 sin60 1031 y b mm= = =

Tm chn 2:

Chiu di 2 6000l R mm= =

Chiu rng 212 xxb +=

Chn x1 = 400 mm

( )0 0 01h =b sin 90 -60 =140sin30 =70mm

( ) ( )bv 1 1nglang2 0 0

H +h - h +y (2530+500) - (70+1031)x = =

sin60 sin60= 2227 mm

2b =400+2227=2627mm

Tm hng dng cng t nghing 1 gc 60o so vi phng ngang, cch tm chn kh

140mm.

3.3.4 H thng phn phi nc

ng knh ng dn

Vn tc nc chy trong ng dn dao ng t 1- 2 m/s. Chn vn tc dng chy trong

ng dn vd = 1,2 m/s

d =d

4 q

24 3600 v

=4 900

24 3600 1,2

=0,105 m = 105 mm

Chn ng knh ng dn l 110 mm.

Kim tra li vn tc nc chy trong ng dn

c 2 2

4 q 4 900v =

d 24 3600 0,11 24 3600

=

= 1,1 m/s

T ng dn chia lm hai ng chnh vo 2 n nguyn


26/45

ng knh ng chnh

Vn tc nc chy trong ng chnh 1 2 m/s. Chn vc = 1,2 m/s

c

c

4q 4 900d =

24 3600 2 v 24 3600 2 1,2

=

=0,074m =74mm

Chn ng chnh l ng nha PCV c ng knh l 75mm

Tnh li vn tc nc chy trong ng chnh

c 2 2c

4 q 4 900v =

d 24 3600 2 0,075 24 3600 2

=

= 1,18 m/s

Nc trong ng chnh s c chia lm 4 ng nhnh, phn phi nc cch b 0,3m.

Ti mi nhnh b tr van iu tit lu lng, van o lu lng v ng co.

ng knh ng nhnh

Vn tc nc trong ng nhnh phn phi nc dao ng t 4 8 m/s. Chn v n = 6m/s.

nn

4q 4 900d =

24 3600 4 2 v 24 3600 4 6

=

=0,0235 m = 23,5mm

Chn ng nhnh l ng nha PVC c ng knh 25 mm

Kim tra li vn tc trong ng nhnh

n 2

4 900v = 5,3

0,025 24 3600 4

=

m/s

Trn ng nhnh c c l. ng knh mi l l 5mm. Chn vn tc nc mi l vl

= 6m/s

Lu lng nc mi l:2 2

-3 3 3lo lolo

v d 6 0,005q = = =0,1210 m /s = 0,432m /h

4 4

S l trn mi nhnh

900N =

4 24 0,432 = 22 l

Cc ng c t di y b cch y b 0,3m. Ti mi ng nhnh c b tr van iu

chnh lu lng v thit b o lu lng m bo vic phn phi nc u trong

b.

ng dn nc thi sang b aerotank


27/45

Vn tc nc chy trong ng 0,1 0,5 m/s. Chn v = 0,5 m/s

4q 4 900D=

24 3600 v 24 3600 0,5

=

= 0,163 m

Chn ng l ng nha PVC c ng knh l 225 mm Kim tra li vn tc trong ng

n 2

4 900v =

0,225 24 3600

= 0,262m/s

3.3.5 Mng thu nc

Trong b UASB ta b tr 2 mng thu nc t dc theo chiu rng ca b. Mng thu

nc c to dc dn v cui b ri theo ng ng a sang b aerotank.

Lu lng nc vo mi mng

3 3m

q 900Q = 5,21.10 m /h

2 2 24 3600

= =

= 5,21 l/s

Mng c tit din hnh ch nht. Vn tc nc chy trong mng dao ng t 0,1 0,4

m/s. Chn vn tc ca nc chy trong mng l vm = 0,2 m/s.

Tit din t ca mng

-3-3 2m

um

Q 5,21 10

S = = =26,05.10 mv 0,2

B rng ca mng bng 2 ln chiu cao ca mng, b = 2h

Su = hu b = 0,7h 2h = 1,4h2

3uS 26,05 10h =

1,4 1,4

= = 0,136 m = 136 mm

Chn h = 140 mm

Vy b rng ca mng b = 2 140 =280 mm

Mng c lm bng thp khng g, c b dy 5mm

Chu vi t ca mng

P = 2 hu + b = 2 0,7 140 + 280 = 476 mm

Bn knh thy lc ca mng

uS 0,7 140 280R =P 476

= = 57,6 mm

dc ca mng c tnh theo cng thc Maning ( cng thc 3-8, iu 3.20, TCXD51:2008, trang 10)


28/45

23

m2 23 33 3

Q n 5,21.10 0,012i = 0,0161

S R 26,05.10 (57,6.10 )

= =

_ Vy dc ca mng, i = 0,0161

_ Xung quanh mi mng b tr 2 thanh rng ca c chiu di 6m, b dy

3mm.Vi khong cch 500 mm b tr 1 inh c c nh.

_ Chiu cao 1 rng ca 70mm

_ on vt nh rng ca 50mm

_ Chiu cao c thanh 160 mm

_ Khong cch gia hai rng ca l 60 mm

_ Nc c dn ra ngoi bng ng nha PVC ng knh 60mm3.3.6 Tnh lng bn cn cho vo b thi im ban u

Chn thi gian lu bn l 70 ngy

Lng bn nui cy ban u cho vo b (TS = 5%)

3 3

ss rb

C V 30kgSS/m 270m 1 tanM = =

TS 0.05 1000kg= 162 tn

Trong :

Css: Hm lng bn trong b, bn nui cy ban u ly t bn ca b

phn hy k kh t qu trnh l nc thi sinh hot cho vo b vi hm lng

30KgSS/m 3

Vr: Th tch ngn phn ng m3

TS: Hm lng cht rn cho bn nui cy ban u.

Hm lng COD ca nc thi sau khi x l k kh

ra COD vaoCOD =(1-E )COD =(1-0,65)1245= 435,75 mgCOD/l

Hm lng BOD ca nc thi sau khi x l k kh:

ra BOD vaoBOD =(1-E )BOD =(1-0,7) 800 = 240 mgBOD/l

Lng sinh khi hnh thnh mi ngy

( )[ ]

cd

xk

QSSYP

+

=

1

0

( )

( )

3 3

1

1245 435,75 / 1800 /

0,04 / 1 0,015 70 1000 /x

gCOD m m ngay

P kgVS kgCOD ngay ngay g kg

= +


29/45

28,4 /xP kgVS ngay =

c : Thi gian lu bn, chn c = 70 ngy

Q : Lu lng trung bnh ngy, Q = 1800 m3/ngym

Y : H s sn lng bn, chn Y = 0,04mgVSS/mgCOD

Kd : H s phn hy ni bo, Kd = 0.015 ngy-1

Lng bn bm ra mi ngy

3ww 3

ss

P 28,4kgVS/ngayQ = = =1,262m /ngay

0,75C 0,75kgVS/kgSS30KgSS/m

Lng cht rn t bn d3 3

ss w SSM =Q C =1,262m /ngay30kgSS/m =37,86 kgSS/ngay

Chn 2 ng thu bn c ng knh l 90 mm c c l ng knh 20 mm, mi l

cch nhau 300mm. Bn c x nh p lc thy tnh ca ct nc theo nh k c b

sung thm 1 my bm 1HP, ti ng thu bn c lp van x mt chiu. Ba ng thu bn

c t dc theo chiu di b cch y b khong 1000mm. Sau cc ng thu bn

trong s dn vo mt ng chung c ng knh110mm.

3.3.7 Tnh lng kh sinh ra v ng thu kh

Th tch kh sinh ra i vi 1 kgCOD b kh l 0,5 m3

Vy th tch hn hp kh sinh ra trong mt ngy

V kh = 0,5 GCOD = 0,5m3 1456,7 kgCOD/ng = 728,4 m3/ ngy

Kh methane sinh ra khi 1kgCOD b kh l 0,35m3,chim 70% tng lng kh

sinh ra. Vy th tch kh methane sinh ra trong 1 ngy

VCH4 = 0,7 728,4 = 510 m3/ ng

ng thu kh t trn ngn lng cch mt nc 0,3m bao gm 6 ng.Vn tc kh

trong ng dao ng t 10 15 m/s. Chn vk = 12 m/s. Vy ng knh ng cn

b tr:

khik

k

4 4 728,4d =

24 3600 v 6 24 3600 12 6

V

=

=0,0122 m= 12,2mm

Chn ng st trng km c ng knh 12mm

Kim tra li vn tc kh trong ng dn kh

khik 2 2k

4 V 4 728,4v = 24 3600 d 6 24 3600 0,012 6

= = 12,4 m/s


30/45

Cc ng thu kh sau s dn sang ng chnh c ng knh 32mm c lm

bng nha PVC.

Vn tc kh trong ng chnh

-3 24 728,4v =

24 3600 (32 10 )

= 10,5 m/s

3.4 Tnh ton b aerotank

3.4.1 Cc thng s u vo

_ Lu lng nc thi Q = 1800m3/ ng

_ COD = 435,75 mg/l

_ BOD = 240mg/l

_ Gi s SS sau khi qua b UASB tip tc gim i mt lng 50%. Vy

lng SS vo b Aerotank l 144 mg/l

Gi s theo kt qu thc nghim ta tm c cc thng s ng hc sau:

Ks = 45mg/l; Y = 0,45mg/l; kd = 0.04ngy-1

C th p dng cc iu kin sau tnh ton qu trnh bn hot tnh xo trn

hon ton:

_ T s MLVSS/MLSS = 0,75_ Hm lng bn tun hon (tnh theo cht rn l lng) , Xr= 8500mg/l

_ Hm lng bn hot tnh trong b aerotank (MLVSS) , X= 3000mg/l

_ Thi gian lu bn trung bnh 10c = ngy

_ Nc thi sau lng t QCVN 24:2009, loi B. BOD5 u ra 50mg/l, COD =

100mg/l, gi s sau khi qua b aerotank v b lng SS gim 60%. Vy SS =

57,6 mg/l ( gm 65% c kh nng phn hy sinh hc)_ T s BOD5/BODL = 0.68;

_ H s chuyn i BOD5 v BOD20 l 0,68;

_ Hm lng bn hot tnh lng xung y b lng c hm lng cht rn 0.8%

v khi lng ring l 1,008kg/L;

_ Hiu sut chuyn ha oxy ca thit b khuych tn l 9%, h s an ton l 2;

_Oxy chim 21% trng lng th tch khng kh v khi lng ring khng kh

l 1,2kg/m3;


31/45

_ Loi v chc nng ca b: b aeroten khuy trn hon ton.

Cc thng s tnh ton c bn cho aeroten kiu xo trn hon ton c th tham

kho theo trang 511 sch X l nc thi th v cng nghip tnh ton

thit k cng trnh (Lm Minh Trit , Nguyn Phc Dn, Nguyn ThanhHng)

3.4.2 Xc nh nng ha tan BOD5 ca nc thi u ra

S lm vic ca h thng

Trong

Q, Qr, Qw, Qe : lu lng nc u vo, lu lng bn tun hon, lu lng

bn x v lu lng nc u ra, m3/ ng

S0, S : nng cht nn (tnh theo BOD5) u vo v nng cht nn sau

khi qua b Aerotank v b lng, mg/lX, Xr, Xe : nng cht rn bay hi trong b Aerotank, nng bn tun hon

v nng bn sau khi qua b lng, mg/l

Phng trnh cn bng vt cht

BOD5 u ra = BOD5 ha tan i ra t b Aerotank + BOD5 cha trong lng

cn l lng u ra

Trong :

BOD5 u ra :50mg/l

B Aerotank B lng

Q, Xo,S

oQ

e, S, X

e

Qw, X

r

Qr, Xr, S


32/45

BOD5 ha tan i ra t b Aerotank l S, mg/l

BOD5 cha trong cn l lng u ra c xc nh nh sau:

Lng cn c th phn hy sinh hc:

0,65 57,6 = 37,44 mg/LBODL ca cn l lng d phn hy sinh hc ca lc thi sau lng :

37,44 (1,42 mg O2 tiu th/mg t bo) = 53,2 mg/L

BOD5 ca cn l lng ca nc thi sau lng:

BOD5 = BODL 0,68 = 53,2 0,68 = 36,2mg/l

BOD5 ha tan ca nc thi sau lng :

50 = S + 36,2

Vy S = 13,8 mg/L

Hiu qu x l tnh theo BOD5 ha tan

00

0

S -S 240-13,8E = = = 94,25

S 240 %

Vi S0 l hm lng BOD5 u vo b aerotank.

Hiu qu x l BOD5 ca b aerotank:

240-50

E= =79,17240 %

3.4.3 Tnh th tch ca b

Th tch b aeroten tnh theo hai cng thc sau:

0( )

(1 )c

d c

Y S SX

k

=

+ +

rV

Q =

Trong :

c : thi gian lu bn;

Q: lu lng nc thi;

Y: h s sn lng t bo;

S0: BOD5 ca nc thi vo aerotank;

S: nng BOD5 sau khi lng;

X: hm lng t bo cht trong b;K: h s phn hy ni bo.


33/45

Thay vo phng trnh trn ta xc nh c th tch b aerotank:

0c

cd

QY(S -S)V=

X(1+k )

3

-110 ngay1800m /ngay0,45(240 - 13,8)mg/LV=

3000mg/L(1+0,04ngay 10)= 436,2 m3

Chn th tch ca b l: 436m3

Thi gian lu nc trong b l:

V 436

= = 24 = 5,81hQ 1800

3.4.4 Xc nh kch thc b

Chn chiu cao hu ch ca b l hhi = 5m, chiu cao bo v l hbv = 0,5m. vy chiucao tng cng ca b l:

Htc = 5 +0,5 = 5,5m

Din tch b

hi

V 436S = = = 87,2

h 5 m2

Chn kch thc b aerotank nh sau: L B H = 11m 8m 5,5m

3.4.5 Tnh lng bn d thi b mi ngy, lu lng bn tun hon

H s sn lng quan st(Yobs) tnh theo phng trnh:

0,450,32mg/mg

1 1 0,04 10obsd c

YY

K= = =

+ +

Trong

Y : h s sn lng, Y = 0,45 kgVSS/kgBOD5

Kd : h s phn hy ni bo, Kd = 0,04 ngy-1

c: tri gian lu bn, c = 10 ngy.

Lng bn sinh ra mi ngy do kh BOD5 (tnh theo VSS)

PX = Yobs Q (BODvao BODra)

Px(vss) = 0,32 1800m3/ngy (240 13,8)g/m3 10-3kg/g = 130,3kgVSS/ ngy

Tng lng bn sinh ra mi ngy theo SS:

Px(ss)= 130,3/0,75 = 173,7 KgSS/ ngy


34/45

Lng cn d hng ngy phi x i

P x = Px(SS) - QSSra = 173,7 - 180057,610-3 = 70,02 kg/ngy

Tnh lng bn x ra hng ngy (Qw) t y b lng theo ng tun hon bn

c =eerw XQXQ

VX+

Qw =e e c

r c

VX Q X

X

Trong

V : Th tch b Aerotank, V = 436m3

X :Nng cht rn bay hi trong b aerotank, X = 3000 mg/l

c:Thi gian lu bn, c = 10 ngy

Qe : Lu lng nc a ra ngoi t b lng (lng nc thi ra khi h

thng). Xem nh lng nc tht thot do tun hon bn l khng ng k nn

Qe = Q = 1800 m3/ ng

Xe : Nng cht rn bay hi u ra ca h thng

Xe = 0,75 SSra = 0,7557,6 = 43,2 mg/lXr : Nng cht rn l lng c trong bn tun hon

Xr = 8500 0,75 = 6375 mg/l = 6,375 kg/m3

3436 3 1800 43,2 10 10Q =w

6,375 10

= 8,32 m3/ ng

Tnh h s tun hon t phng trnh cn bng vt cht vit cho b lng (xem

nh lng cht bay hi u h thng l khng ng k)

Ta c:X(Q +Qr) = XoQ + XrQr

Trong

Q: lu lng nc thi, Q = 1800m3/ ng

X: Nng VSS trong b aerotank, X = 3000 mg/l

Qr: Lu lng bn hot tnh tun hon

Xo : Nng VSS trong nc thi dn vo b aerotank, Xo = 0

Xr : Nng VSS trong bn tun hon, X r= 6375 mg/l


35/45

X(Q + Qr) = XrQr

Vy ta c:

r

r

Q X 3000=

Q X -X 6375 - 3000

= = = 0,89

Lu lng bn tun hon

Qr = Q = 1800 0,89 = 1602m3/ ng = 66,75 m3/h

Kim tra li th tch LBOD v t s F/M

Ti trng th tch:

3 3

0 5BOD 3

QS 1800m /ngay240gBOD /mL = =

V 436m 1000g/kg= 0,99 kgBOD/ m3.ng

Gi tr ny nm trong khong cho php (LBOD = 0,8 1,9)

T s F/M

0 240 /

5,81 / 24 / 3000= =

SF mg L

M X h h ngay= 0,33 ngy -1

Gi tr ny nm trong khong cho php (0,2 0,6 ngy-1)

3.4.6Lng oxy cn cung cp cho b aerotank da trn BOD20

Ta c H s sn lng quan st(Yobs) tnh theo phng trnh:

0,450,32

1 1 0,04 10obsd c

YY

K= = =

+ + mg/mg

Lng bn d sinh ra mi ngy theo VSS l Px = 130,3kgVSS/ ngy

Vy lng oxy cn thit trong iu kin tiu chun

00 x

Q(S -S)OC = -1,42P

1000f

0

1800(240 - 13,8)OC = -1,42130,3 =413,7

0,681000 kgO2/ngy

Vi

0OC : lng oxy cn thit theo tiu chun ca phn ng 200C


36/45

f: h s chuyn i t BOD5 sang COD hay BOD20 v f = BOD5/COD

thng t 0,65 0,68. Chn f = 0,68.

1,42: h s chuyn i t t bo sang COD

Lng oxy thc t cn s dng cho b:(TS.Trnh Xun Lai, sch Tnh ton thit k cc cng trnh x l nc thi,

cng thc 6-16, trang 106)

0s20

t (t-20)sh

C 1 1OC =OC

C -Cd 1.024

Trong :

:H s hiu chnh lc cng b mt theo hm lng mui, i vi nc

thi thng ly = 1

Csh :Nng oxy bo ha trong nc sch 26oC, Csh = 8,09mg/l

Cs20: Nng oxy bo ha trong nc sch 20oC, Cs20 = 9,08 mg/l

Cd : Nng oxy cn duy tr trong cng trnh (mg/l). Khi x l nc

thi thng ly Cd = 1,5 2 mg/l. Chn Cd = 2mg/l

: H s hiu chnh lng oxy ngm vo nc thido nh hng cahm lng cn, cht hot ng b mt, loi thit b lm thong , hnh dng v

kch thc b, c gi tr t 0,6 0,94

t (26-20)

9,08 1 1OC =430,2

1 8,09-2 0,71.024

= 794,8 kgO2/ngy

Lng khng kh/m3 nc thi = 794,8 /1800 =0,442 kgO2/m3 nc thi

Trong khng kh oxi chim 21% th tch; gi s rng trng lng ring ca khng khl 1,2Kg/m3. Vy lng khng kh cn thit cho qu trnh l:

2O

KK

M 794,8M = = =3154

0,211,2 0,252m3/ ng

Tc oxy ha ca 1g bn hot tnh

0 240 13,8 0,3115,81 3000

24

S S

ngayX hh

= = =

mgBOD5/mgbn.ngy

Tnh lng khng kh cn thit cung cp vo b


37/45

tkk

OCQ = f

OU

Trong

OCt : Lng oxy thc t cn s dng cho b, OCt = 794,8kgO2/ngyf: H s an ton, thng t 1,5 2. Chn f = 2

OU : Cng sut ha tan oxy vo nc thi ca thit b phn phi tnh

theo gam oxy cho mt m3 khng kh.

OU = Ou h = 7 5 = 35gO2/m3

Ou : Cng sut ha tan oxy vo nc thi ca thit b phn phi tnh

theo gam oxy cho mt m3 khng kh, su ngp nc h = 1m. Ou = 7gO 2/m (TS.

Trnh Xun Lai, sch Tnh ton thit k cc cng trnh x l nc thi, bng 7.1, trang112)

h: su ngp nc ca thit b phn phi kh, ly bng chiu su hu

ch ca b, h = 5m

-3kk794,8

Q = 2 = 45417,135 10

m3/ngy = 31539,7 L/pht

3.4.7 S lng thit b khuch tn kh

_ Chn thit b khuch tn kh dng a xp, ng knh 170 mm, din tch bmt F = 0,0227m2, cng thi kh 200L/pht.a = 12 m3/gi.a

_ su ngp nc ca a phn phi kh ly bng chiu su hu ch ca b H =

5 m (t st y b)

S a cn phn phi trong b

kkQ 31539,7L/phutn= = =157,7L 200l/ph.dia

a

Chn n = 158 a

Chn kiu v tnh ton thit b cung cp kh, ng ng dn kh

cung cp lng oxi cn thit cho qu trnh x l, thng dung my khuy

trn c kh b mt to ra mng nc, tia nc, git nc tip xc vi khng kh

ly oxy hoc dng h thng my thi kh, ng dn v thit b phn phi kh vo b

aerotank ly oxy.


38/45

ng dn khng kh: dn khng kh c th chn ng thp khng r, ng nha

gia cng bng si thy tinh, ng PE hoc ng nha chu c s thay i ca nhit

. Tc chuyn ng ca khng kh qua ng dn v qua h thng phn phi t 10

15m/s, qua l phn phi t 15 20m/s.

3.4.8 Tnh ton my thi kh

p lc cn thit ca my thi kh

Hm = h1 + hd + H

Trong

h1 : Tn tht trong h thng vn chuyn, h1 = 0,4 m

hd :Tn tht qua a phun, hd = 0,5m

H : su ngp nc ca ming vi phun. H = 5m

Hm = 0,4 + 0,5 + 4 = 5,9 m

p lc my thi kh tnh theo Atmotphe

mm

H 5,9P = 0,583

10,12 10,12= = atm

Nng sut yu cu

Qkk= 45417,1 m3/ng = 0,526 m3/s

Cng sut my thi kh

(TS Trnh Xun Lai, Sch Tnh ton thit k cc cng trnh x l nc thi, cng thc

6.20, trang 108)

0,283

1 2m

1

GRT pP = -1

29,7ne p

Trong

Pm : Cng sut yu cu ca my nn kh, kW

G : Trng lng ca dng kh, kg/s

G = Qkk kh = 0,526 1,2 = 0,6312 kg/s

R : Hng s kh, R = 8,314 KJ/K.moloK

T1 : Nhit tuyt i ca u khng kh vo

T1 = 273 + 27 = 300 K

P1 : p sut tuyt i ca khng kh u vo, P1 = 1 atm


39/45

P2 : p sut tuyt i ca khng kh u ra

P2 = Pm + 1 = 0,583 + 1 = 1,583 atm

K-1n= =0,283

Kv i vi khng kh K = 1,395

29,7 : H s chuyn i

e : Hiu sut ca my t 0,7 0,8, chon e = 0,8

0,283

m

0,6312 8,314 300 1,583P = -1 32,5 kW

29,7 0,283 0,8 1

=

Tnh ton ng ng dn kh

Vn tc kh trong ng dn chnh, chn vk= 13 m/s

Lu lng kh cn cung cp, Qk= 0,526 m3/s

ng knh ng phn phi chnh

k

k4 Q 4 0,526D = 0,227v 13

= =

m

Chn ng dn chnh l ng st trng km, c ng knh l 225mm

Kim tra li vn tc kh trong ng dn

2 2kk

4 Q4 0,526v = 13,2

D 0,225 = = m/s

vknm trong khong cho php (10 -15 m/s)

T ng chnh ta phn thnh 11 ng nhnh cung cp kh cho b .

Lu lng kh qua mi ng nhnh

kkQ 0,526q = 0,0478

15 11= = m3/s

ng knh ng nhnh.Chn vn tc kh trong ng nhnh vn = 12m/s

n

k4 q 4 0,0478d = 0,071v 12

= =

m

Chn ng nhnh l loi ng st trng km co ng knh d = 75mm

Kim tra li vn tc kh trong ng nhnh

2 2

k

n

4 q 4 0,0478v = 12,1

d 0,071

= =

m/s


40/45

vn nm trong khong cho php (10 -15 m/s)

3.4.9 Tnh ton ng ng dn nc thi vo b

Chn vn tc nc thi trong ng dn, v= 0,5 m/s

Lu lng nc thi : Q = 1800m3

/ngy = 0,021 m3

/s4 Q 4 0,021

D = 0,231v 0,5

= =

m = 231mm

Chn ng dn nc thi vo b l loi ng nha PVC c ng knh 250mm

Kim tra li vn tc nc trong ng dn

2 2

4 Q 4 0,021v = 0,43

D 0,25

= =

m/s

Tnh ton ng ng dn bnLu lng bn tun hon Qr =1602 m3/ ng = 0,0185 m/s

Chn vn tc bn trong ng, v= 0,5 m/s

rb

4 Q 4 0,0185D = 0,217

v 0,5

= =

m = 217mm

Chn ng dn bn l loi ng nha PVC c ng knh 225 mm

Bm tun hon bn

Lu lng bm Qr= 0,0185 m/s

Ct p bm, H =8m

Q gH 0,018510009,818N= = 1,82

1000 10000,8

= kW

Chm bm c cng sut 2,5HP

3.5 Tnh ton b lng

B lng dng chn gi bn hot tnh qua x l b Aeroten hay mng visinh cht t b Aeroten.

3.5.1 Kch thc b lng

Din tch mt bng ca b lng (TS.Trnh Xun Lai, Sach Tnh ton thit k

cc cng trnh x l nc thi, cng thc 9-8, trang150)

0

Lt

Q(1+ ) CS =

C V

Trong :


41/45

Q : lu lng nc thi, m3/h

:h s tun hon bn, =0,89

C0 : nng bn hot tnh trong b aerotank

C0 = 3000/0,75 = 4000 g/m3

Ct : nng bn trong dng tun hon, Ct = Xr = 8500 g/m3

v L vn tc lng ca mt phn chia ng vi CL, m/h

Theo cng thc 9-7, Sch Tnh ton thit k cc cng trnh x l nc thi, trang 150

CL = Ct/2 = 8500/2 = 4250 g/m3

Vn tc lng vL c xc nh theo cng thc thc nghim 9-9, Sch Tnh ton thit

k cc cng trnh x l nc thi, trang 150-6 -6

L-K.C .10 -600425010

L maxv = v e =7e 0,55= m/h

Vi

vmax = 7m/h

CL= 4250g/m3

K =600

Din tch phn lng ca b

75(1+0,89) 4000S = 121,38500 0,55

=

m2

Chn S = 122m2

Nu k c din tch ca bung phn phi trung tm

Sb = 1,1 122 =134,2 m2

ng knh b lng

b4 S 4134,2

D= = = 13m

ng knh bung phn phi trung tm

d = 0,25 D = 3,25 m

Din tch bung phn phi trung tm

2 2d 3,25f = 8,3

4 4

= = m2

Din tch vng lng ca mt b

SL = 134,2 8,3 = 125,9 m2


42/45

Chn SL = 126 m2

Ti trng thy lc

3

2

L

Q 1800m /ngda = = 14,3

S 126m

= m3/m2.ng

Vn tc i ln ca dng nc trong b

a 14,3v = 0,6

24 24= = m/h

Mng thu nc t vng trn c ng knh bng 0,8 ng knh b

Dm = 0,8 D = 0,8 13 = 10,4m

Chiu di ca mng thu nc

L = Dm = 3,14 10,4 =32,7 mTi trng thu nc trn 1m di ca mng

3

2

Q 1800m /ngda = = 55,1

L 32,7m= m3/m di .ng

Xc nh chiu cao b

Chn chiu cao b, H = 4m

Chiu cao d tr trn mt thong h1 = 0,3 m

Chiu cao ct nc trong b 3,7 m. Gm:

Chiu cao phn nc trong : h2 = 1,5m

Chiu cao phn chp y b c dc 2% v tm:

h3 = 0,02 D/2 =0,02 13/2 =0,13m

Chiu cao phn cha bn hnh tr

h4 = H h1 h2 h3 = 4 0,3 1,5 0,13 = 2,07m

Th tch phn cha bn

Vb = Sb h4 = 134,2 2,07 = 277,8 m3

Nng bn trung bnh trong b

L ttb

C + C 4250 8500C = 6375

2 2

+= = g/m3 = 6,375 kg/m3

Lng bn cha trong b lng

G bn = Vb Ctb = 277,8 6,375 = 1771 kg

3.5.2 Thi gian lu nc trong b lngTh tch b lng


43/45

V = H Sb = 3,7 134,2 = 496,54 m3

Nc i vo b lng

Qv = (1 + ) Q = 1,89 1800 = 3402 m3/ ng = 141,75 m3/h

Thi gian lng

v

V 496,54 T = 3,5

Q 114,75= = gi

3.6 Kh trng nc thi

Sau cc giai on x l: c hc, sinh hc,, song song vi vic lm gim nng

cc cht nhim t tiu chun quy nh th s lng vi trng cng gim ng k

n 90 95%. Tuy nhin, lng vi trng vn cn cao v vic kh trng l iu cnthit. thc hin vic kh trng nc thi, c th s dng cc bin php nh clo

ha, zon ha, kh trng bng tia hng ngoi UV. Vic kh trng bng clo tng i

n gin, r tin v hiu qu chp nhn c nn c s dng nhiu cng trnh x

l.

Bng: Cc thng s thit k cho b kh trng chlorine

Thng s Gi tr

Tc dng chy, m/pht 2 4,5Thi gian tip xc, pht 15 - 30T s di/rng, L/B 10 - 1

Chn thi gian tip xc t = 30 pht

Th tch b kh trng

V = Q t =1800

30 37,524 60

=

(m3)

Chn chiu cao ca b H = 2,5mChn chiu cao bo v hbv = 0,5m

Din tch b mt ca b

237,5 15( )

2,5

VF m

H= = =

Chn kch thc b B L =3 5

xo trn nc thi vi ha cht, ta thit k mng trn c vch ngn theo kiu

ziczac nhm tng kh nng tip xc gia nc v ha cht. Mng gm 5 vch ngn


44/45

Chiu dy mi vch ngn chn l 100mm.

Khong cch gia cc vch ngn: 4,5/5 = 0,9 m

Chiu di vch ngn bng 2/3 chiu rng b

3 2 3 22 3vnBL m = = =

Tnh lng clo cn thit trong 1 gi.

1000aQ

c

=

Q: Lu lng nc ngun x l. Q=1800m3/ngy

a: Liu lng clo kh trng i vi nc thi sau khi x l sinh hc hon ton

3g/m3(iu 7.198 TCXD 51-2008).

1800 3

0,225( / )1000 24

c kg h

= =

Lng clo cn thit trong 1 ngy l: 24 h 0,225 kg/h = 5,4 kg

3.7B nn bn

Bn hot tnh d ngn lng c m cao, cn phi t n d m thch hp

xy dng trc khi cho qua cc cng trnh x l tip theo hoc thi ra mi trng

lm phn bn (nu lng cn ti t).

Cc thng s tnh ton b nn bn ng c xc nh:

Lng bn d: l tng lng bn sinh ra t b UASB v b lng

Lu lng bn thi ra b UASB c bm vo b cha bn l:

Qw = 1,262 m3/ngy

Lng bn thi ra khi b UASB 28,4 /ssM kgVS ngay =

Lu lng bn thi b b lng c a vo b cha bn

vi Qb = 8,32 m3/ngy

Lng bn thi b trong b lng

Mb = 70,02 kgVS/ngy

Tng lng bn

M = 28,4 + 70,02 = 98,42 kgSS/m3


45/45

Vy tng lu lng bn vo trong b cha bn l

Qnen = 1,262 +8,32 = 9,582 m3/ngy.

Din tch b nn bn

298,42 1,9750

MA ma

= = =

Chn A = 2 m2

Vi a: ti trng ring ca bn hot tnh

a = (50-70)kgSS/m2.ngy. Chn a = 50kgSS/m2.ngy

chn thi gian lu bn l 1 ngy

vy th tch ca b nn bn V = 9,582 m3/ngy 1ngy = 9,582 m3

H = 9,582/2 = 4,8 m

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