xulynuocthai son hoan chinh 5859
TRANSCRIPT
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B GIO DC V O TO
K THUT
X L NC THI
Bin son:
ThS. Lm Vnh Sn
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K THUT X L NC THI
n bn 2014
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MC LC I
MC LC
MC LC ...................................................................................................................I
HNG DN ............................................................................................................. V
BI 1: NHNG VN CHUNG V X L NC THI .................................................. 1
1.1 PHN LOI NC THI ...................................................................................... 1
1.1.1 Nc thi sinh hot ......................................................................................... 1
1.1.2 Nc thi cng nghip (nc thi sn xut) ........................................................ 3
1.1.3 Nc thi l nc ma ..................................................................................... 4
1.2 THNH PHN, TNH CHT CA NC THI VA CC DNG NHIM BN ............... 5
1.2.1 Lu lng nc thi ......................................................................................... 5
1.2.2 Dao ng ca lu lng nc thi ................................................................... 13
1.2.3 Chn lu lng thit k .................................................................................. 14
1.2.4 Thnh phn, tnh cht nc thi ...................................................................... 14
1.3 BO V NGUN NC KHI B NHIM BN, KH NNG T LM SCH CA NGUN NC ............................................................................................................. 19
1.3.1 Du hiu ngun nc nhim bn. Kh nng t lm sch ca ngun nc ............. 19
1.3.2 Nguyn tc x nc thi vo ngun ................................................................. 22
1.3.3 Xc nh mc x l nc thi ..................................................................... 22
1.4 S CNG NGH X L NC THI ............................................................... 25
1.4.1 C s la chn cng trnh x l nc thi: ........................................................ 25
1.4.2 Dy chuyn cng ngh trm x l nc thi: .................................................... 27
1.4.3 Gii thiu 1 s dy chuyn x l nc thi: ...................................................... 28
BI 2: X L NC THI BNG PHNG PHP C HC ........................................... 34
2.1 KHI NIM V PHNG PHP X L NC THI BNG PHNG PHP C HC 34
2.1.1 Thit b chn rc: .......................................................................................... 34
2.1.2 Thit b nghin rc: ....................................................................................... 34
2.1.3 B iu ha: ................................................................................................. 35
2.1.4 B lng ct: .................................................................................................. 35
2.1.5 B lng: ....................................................................................................... 36
2.1.6 Lc .............................................................................................................. 36
2.1.7 Tuyn ni, vt du m ................................................................................... 36
2.2 TNH TON THIT K CC CNG TRNH C HC ............................................... 37
2.2.1 Song chn rc ............................................................................................... 37
2.2.2 B lng ct ................................................................................................... 41
2.2.3 B vt du m .............................................................................................. 48
2.2.4 Tuyn ni: .................................................................................................... 51
2.2.5 X l bng phng php lng ......................................................................... 62
2.2.6 X l bng phng php lc .......................................................................... 83
2.3 B IU HA .................................................................................................... 97
2.3.1 B iu ho lu lng v cht lng ................................................................ 99
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II MC LC
2.3.2 B iu ho ch yu lm nhim v iu ho lu lng ...................................... 100
2.3.3 Cc bc tnh b iu ha theo phng php th .......................................... 100
BI 3: X L NC THI BNG PHNG PHP HA L ......................................... 110
3.1 PHNG PHP KEO T TO BNG .................................................................. 110
3.1.1 Keo t v cc ha cht dung trong keo t ....................................................... 110
3.1.2 Cc thit b v cng trnh ca qu trnh keo ..................................................... 118
3.1.3 Thit b ha trn cht phn ng ..................................................................... 124
3.1.4 B phn ng to bng kt ta ........................................................................ 125
3.2 PHNG PHP TRUNG HA ............................................................................ 137
3.2.1 Trung ho bng trn nc thi cha axit v nc thi cha kim. ...................... 138
3.2.2 Trung ho bng cch cho thm ho cht vo nc thi. .................................... 139
3.2.3 Trung ho nc thi cha axit bng cch lc qua lp vt liu lc trung ho. ........ 141
3.2.4 Trung ha nc thi mang tnh kim bng kh thi c tnh acid: ......................... 143
3.3 X L NC THI BNG PHNG PHP TUYN NI ....................................... 144
3.3.1 Gii thiu chung. .......................................................................................... 144
3.3.2 Phn loi ..................................................................................................... 144
3.4 PHNG PHP HP TH ................................................................................. 146
3.5 X L BNG PHNG PHP HP PH ............................................................. 147
3.5.1 C s qu trnh hp ph ................................................................................ 147
3.5.2 Cht hp ph ............................................................................................... 148
3.5.3 Phn loi hp ph. ....................................................................................... 149
3.6 X L NC THI BNG PHNG PHP TRCH .............................................. 150
3.6.1 Nguyn l c bn ......................................................................................... 150
3.6.2 K thut trch ly ........................................................................................... 150
3.6.3 Phn loi ..................................................................................................... 150
3.7 X L NC THI BNG PHNG PHP TRAO I ......................................... 151
3.7.1 Mt s khi nim v qu trnh trao i ion ....................................................... 152
3.7.2 Cc cht trao i ion ..................................................................................... 152
3.7.3 C s qu trnh trao i ion ........................................................................... 152
3.8 X L BNG MNG ......................................................................................... 153
3.8.1 Thm thu ngc ......................................................................................... 153
3.8.2 Siu lc ....................................................................................................... 155
3.8.3 Thm tch v in thm tch ........................................................................ 156
3.9 X L NC THI BNG PHNG PHP LM THONG V CHNG CT BAY HI ................................................................................................................................. 157
3.9.1 Phng php lm thong .............................................................................. 157
3.10 X L NC THI BNG PHNG PHP OXI KH ...................................................... 159
3.10.1 nh ngha ................................................................................................. 159
3.10.2 Vai tr: ..................................................................................................... 160
3.10.3 Phn loi: .................................................................................................. 160
3.10.4 nh gi phng php oxi ha bc cao: ........................................................ 161
3.10.5 C ch ca qu trnh oxi ha bc cao ............................................................ 162
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MC LC III
3.10.6 Cc phng php oxi ha kh ...................................................................... 166
3.11 X L NC THI BNG PHNG PHP IN HA. ...................................... 167
BI 4: X L NC THI BNG PHNG SINH HC ............................................... 168
4.1 TNG QUAN CC PHNG PHP SINH HC TRONG X L NC THI ........... 168
4.1.1 Nguyn tc: ................................................................................................ 168
4.1.2 C ch chung ............................................................................................... 168
4.1.3 Cc qu trnh sinh hc trong x l nuc thi: ................................................... 170
4.1.4 Cng trnh x l ng dng cc qu trnh phn hu ............................................ 173
4.1.5 Cc yu t nh hng n qu trnh x l sinh hc : ......................................... 173
4.1.6 Vai tr ca vsv trong x l nc thi............................................................... 174
4.2 CNG TRNH X L NC THI TRONG IU KIN T NHIN ........................ 175
4.2.1 Cnh ng ti cng cng v bi lc ............................................................... 175
4.2.2 Cnh ng ti nng nghip .......................................................................... 190
4.2.3 H sinh hc ................................................................................................. 191
4.3 CNG TRNH X L SINH HC NHN TO ....................................................... 197
4.3.1 B lc sinh hc (B Biophin) (c lp vt liu khng ngp nc) .......................... 197
4.3.2 B lc sinh hc c lp VL ngp trong nc thi ................................................. 205
4.3.3 B Aerotank ................................................................................................ 215
4.3.4 B lng 2 .................................................................................................... 243
4.3.5 X l nc thi bng vi sinh k kh (b UASB) .................................................. 252
4.3.6 Mt s cng trnh sinh hc khc ..................................................................... 274
BI 5: X L V S DNG CN NC THI ............................................................ 313
5.1 C TNH CA CN LNG V CC PHNG PHP X L.................................. 313
5.1.1 Thnh phn ................................................................................................. 313
5.1.2 Phn loi cn ............................................................................................... 314
5.1.3 Phng php x l ....................................................................................... 315
5.1.4 B Mtan..................................................................................................... 317
5.1.5 Hm t hoi ................................................................................................ 323
5.1.6 B nn bn .................................................................................................. 329
5.1.7 Sn phi bn ............................................................................................... 334
5.1.8 My p lc bng ti ...................................................................................... 338
5.1.9 My p cn ly tm ........................................................................................ 339
BI 6: KH TRNG NC THI ............................................................................... 340
6.1 TI SAO PHI KH TRNG NC THI ........................................................... 340
6.2 CC PHNG PHP KH TRNG NC THI .................................................. 342
6.2.1 Kh trng bng cc cht xi ha mnh .......................................................... 342
6.2.2 Kh trng bng tia cc tm ............................................................................ 351
6.2.3 Kh trng bng mt s phng php khc ...................................................... 353
BI 7: S CHUNG V C S K THUT QUN L TRM X L........................... 357
7.1 S CHUNG TRM X L ............................................................................. 357
7.1.1 Nhng yu cu v sinh v la chn phng php x l ..................................... 357
7.1.2 Mt bng tng th v cao trnh trm x l ....................................................... 360
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IV MC LC
7.1.3 Phn phi nc thi vo cc cng ................................................................... 364
7.1.4 Thit b o lu lng trn trm x l ............................................................ 367
7.2 C S K THUT QUN L TRM X L NC THI ........................................ 371
7.2.1 Nghim thu cng trnh .................................................................................. 371
7.2.2 Giai on a cng trnh vo hot .................................................................. 372
7.2.3 Nhng phng php kim tra theo di ch lm vic ca cc cng trnh x ...... 374
7.2.4 Nhng nguyn nhn ph hy ch lm vic bnh thng ca cc cng trnh x l. Bin php khc phc. ................................................................................................. 378
7.2.5 T chc qun l v k thut an ton ............................................................... 380
7.2.6 Thng k v cng ngh ca cc cng trnh ..................................................... 381
7.2.7 Mt s s c khi vn hnh cc cng trnh sinh hc ............................................ 383
TI LIU THAM KHO ........................................................................................... 387
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HNG DN V
HNG DN
M T MN HC
Mn hc K thut x l nc thi ny nhm cung cp cho sinh vin chuyn ngnh K
thut mi trng v cc sinh vin cc ngnh lin quan nhg kin thc c bn v nc thi
v nhim nc thi. T nm bt nhng phng php x l nc thi t c hc n l
ha va sinh hc. Sinh vin nm bt quy lut v qu trnh ca cc phng php x l nc
thi. Sinh vin c th tnh ton thit k chi tit cc cng trnh n v trong dy chuyn x
l nc thi v xut cc phng n x l ph hp
NI DUNG MN HC
Ni dung mn hc c c th ha qua 7 bi sau y:
Bi 1. Nhng khi nim v nhim ngun nc v x l nc thi
Bi 2. Phng php c hc trong x l nc thi
Bi 3. Phng php ha l trong x l nc thi
Bi 4. Phng php sinh hc trong x l nc thi
Bi 5. Phng php x l bn cn trong x l nc thi
Bi 6. Kh trng nc thi
Bi 7. Vn hnh v qun l trm x l nc thi
KIN THC TIN
Sinh vin cn phi c trang b cc kin thc v ngun nc, cc ch tiu cht lng
nc, cc quy chun mi trng v nc thi. Sinh vi phi c kin thc v cc qu trnh
thit b c hc, l ha, sinh hc. Ngoi ra phi c kin thc v ton hc, hnh hc v thy
lc vng chc. Sinh vin phi hc trc cc mn : Ha i cng, ha mi trng, ha
sinh, qua trnh thit b cng ngh, thy lc,
YU CU MN HC
Mn hc phi m bo thi lng v c ti liu tham kho phong ph, kin thc phi
c h thng ha c bn sinh vin d nm bt. Mn hc ny l kh ca ngnh nn
i hi phi c kinh nghim thc t chia s thng tin. V c bit phi c nhng bi
tp ln p dng
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VI HNG DN
CCH TIP NHN NI DUNG MN HC
- Sinh vin phi nghe thuyt ging
- Sinh vin tham gia lp hc y l lm bo co chuyn nhm
- Sinh vin phi c ti liu nhiu v mn hc
- Sinh vin phi tham gia lm bi tp ln v n mn hc x l nc thi
PHNG PHP NH GI MN HC
- Nghe ging , bo co chuyn trn lp: 30%
- Lm bi tp ln v v p cui mn: 70%
- Sinh vin tham quan thc t v bo co: cng thm m (nu c)
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BI 1: NHNG VN CHUNG V X L NC THI 1
BI 1: NHNG VN CHUNG V
X L NC THI
1.1 PHN LOI NC THI
hiu v la chn cng ngh x l nc thi cn phi phn bit cc loi nc thi
khc nhau. C nhiu cch hiu v cc loi nc thi, nhng trong ti liu ny tc gi a
ra 3 loi nc thi da trn mc ch s dng v cch x thi nh sau.
1.1.1 Nc thi sinh hot
Nc thi sinh hat l nc c thi b sau khi s dng cho cc mc ch sinh hot
ca cng ng : tm , git gi , ty ra, v sinh c nhn,chng thng c thi ra t
cc cc cn h, c quan, trng hc, bnh vin, ch, v cc cng trnh cng cng khc.
Lng nc thi sinh hat ca khu dn c ph thuc vo dn s, vo tiu chun cp nc
v c im ca h thng that nc.
Thnh phn ca nc thi sinh hat gm 2 lai:
- Nc thi nhim bn do cht bi tit ca con ngi t cc phng v sinh
- Nc thi nhim bn do cc cht thi sinh hat: cn b t nh bp, cc cht ra tri,
k c lm v sinh sn nh.
Nc thi sinh hat cha nhiu cht hu c d b phn hy sinh hc, ngai ra cn c
cc thnh phn v c, vi sinh vt v vi trng gy bnh rt nguy him. Cht hu c cha
trong nc thi sinh hat bao gm cc hp cht nh protein (40 50%); hydrat cacbon
(40 - 50%) gm tinh bt, ng v xenlulo; v cc cht bo (5 -10%). Nng cht hu
c trong nc thi sinh hat dao ng trong khang 150 450mg/l theo trng lng kh.
C khang 20 40% cht hu c kh phn hy sinh hc. nhng khu dn c ng c,
iu kin v sinh thp km, nc thi sinh hat khng c x l thch ng l mt trong
nhng ngun gy nhim mi trng nghim trng.
Lng nc thi sinh hot dao ng trong phm vi rt ln, ty thuc vo mc sng v
cc thi quen ca ngi dn, c th c tnh bng 80% lng nc c cp. Gia lng
nc thi v ti trng cht thi ca chng biu th bng cc cht lng hoc BOD5 c mt
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2 BI 1: NHNG VN CHUNG V X L NC THI
mi tng quan nht nh. Ti trng cht thi trung bnh tnh theo u ngi iu kin
c vi nhu cu cp nc 150 l/ngy c trnh by trong bng 1.1
Bng.1.1 Ti trng cht thi trung bnh 1 ngy tnh theo u ngi
Cc cht Tng cht thi
(g/ngi.ngy)
Cht thi hu c
(g/ngi.ngy)
Cht thi v c
(g/ngi.ngy)
Tng lng cht thi
Cc cht tan
Cc cht khng tan
Cht lng
Cht l lng
190
100
90
60
30
110
50
60
40
20
80
50
30
20
10
Bng 1.2 Thnh phn nc thi sinh hat phn tch theo cc phng php ca
APHA
Cc cht (mg/l) Mc nhim
Nng Trung bnh Thp
- Tng cht rn
- Cht rn ha tan
- Cht rn khng ha tan
- Tng cht rn l lng
- Cht rn lng
- BOD5
- DO
- Tng nit
- Nit hu c
- Nit ammoniac
- NO2
- NO3
- Clorua
- kim
- Cht bo
- Tng photpho
1000
700
300
600
12
300
0
85
35
50
0,1
0,4
175
200
40
-
500
350
150
350
8
200
0
50
20
30
0,05
0,2
100
100
20
8
200
120
8
120
4
100
0
25
10
15
0
0,1
15
50
0
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Nc thi sinh hot c thnh phn vi cc gi tr in hnh nh sau: COD=500 mg/l,
BOD5=250 mg/l, SS=220 mg/l, photpho=8 mg/l, nit NH3 v nit hu c=40 mg/l,
pH=6.8, TS= 720mg/l.
Nh vy, Nc thi sinh hot c hm lng cc cht dinh dng kh cao, i khi vt
c yu cu cho qu trnh x l sinh hc. Thng thng cc qu trnh x l sinh hc cn
cc cht dinh dng theo t l sau: BOD5:N:P = 100:5:1
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BI 1: NHNG VN CHUNG V X L NC THI 3 Mt tnh cht c trng na ca Nc thi sinh hot l khng phi tt c cc cht hu
c u c th b phn hy bi cc vi sinh vt v khong 20-40% BOD thot ra khi cc
qu trnh x l sinh hc cng vi bn.
1.1.2 Nc thi cng nghip (nc thi sn xut)
L lai nc thi sau qu trnh sn xut, ph thuc loi hnh cng nghip. c tnh
nhim v nng ca nc thi cng nghip rt khc nhau ph thuc vo lai hnh cng
nghip v ch cng ngh la chn.
Trong cng nghip, nc c s dng nh l 1 loi nguyn liu th hay phng tin
sn xut (nc cho cc qu trnh) v phc v cho cc mc ch truyn nhit. Nc cp
cho sn xut c th ly mng cp nc sinh hot chung hoc ly trc tip t ngun nc
ngm hay nc mt nu x nghip c h thng x l ring. Nhu cu v cp nc v lu
lng nc thi trong sn xut ph thuc vo nhiu yu t. Lu lng nc thi ca cc
x nghip cng nghip c xc nh ch yu bi c tnh sn phm c sn xut.
Bng 1.3. lu lng nc thi trong 1 s ngnh cng nghip
Ngnh cng nghip Tnh cho Lu lng nc thi
1. Sn xut bia
2. Tinh ch ng
3. Sn xut b sa
4. Nh my hp rau qu
5. Giy trng
6. Giy khng ty trng
7. Dt si nhn to
8. X nghip ty trng
1 lt bia
1 tn c ci ng
1 tn sa
1 tn sn phm
1 tn
1 tn
1 tn sn phm
1 tn si
5,65 (l)
10 20 (m3)
5-6 (l)
4,5 - 1,5
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100 (m3)
1000 - 4000 (m3)
Ngoi ra, trnh cng ngh sn xut v nng sut ca x nghip cng c ngha
quan trng. Lu lng tnh cho 1 n v sn phm c th rt khc nhau. Lu lng nc
thi sn xut li dao ng rt ln. Bi vy s liu trn thng khng n nh v nhiu x
nghip li c kh nng tit kim lng nc cp do s dng h thng tun hon trong sn
xut.
Thnh phn nc thi sn xut rt a dng, thm ch ngay trong mt ngnh cng
nghip, s liu cng c th thay i ng k do mc hon thin ca cng ngh sn
xut hoc iu kin mi trng.
Cn c vo thnh phn v khi lng nc thi m la chn cng ngh v cc k
thut x l. Sau y l mt s s liu v thnh phn nc thi ca mt s ngnh cng
nghip
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4 BI 1: NHNG VN CHUNG V X L NC THI
Bng 1.4. Tnh cht c trng ca nc thi 1 s ngnh cng nghip
Cc ch tiu Ch bin
sa
Sn xut tht
hp
Dt si tng
hp
Sn xut
clorophenol
- BOD5 (mg/l)
- COD (mg/l)
- Tng cht rn (mg/l)
- Cht rn l lng (mg/l)
- Nit (mgN/l)
- Photpho (mgP/l)
- pH
- Nhit (0C)
- Du m (mg/l)
- Clorua (mg/l)
- Phenol (mg/l)
1000
1900
1600
300
50
12
7
29
-
-
-
1400
2100
3300
1000
150
16
7
28
500
-
-
1500
3300
8000
2000
30
0
5
-
-
-
-
4300
5400
53000
1200
0
0
7
17
-
27000
140
Ni chung, nc thi t cc nh my ch bin thc phm c hm lng nit v
photpho cho qu trnh x l sinh hc, trong khi hm lng cc cht dinh dng ny
trong nc thi ca cc ngnh sn xut khc li qu thp so vi nhu cu pht trin ca vi
sinh vt. Ngoi ra, nc thi cc nh my ha cht thng cha 1 s cht c cn c
x l s b kh cc c t trc khi thi vo h thng nc thi khu vc.
C hai loi nc thi cng nghip:
- Nc thi cng nghip qui c sch : l lai nc thi sau khi s dng lm ngui
sn phm, lm mt thit b, lm v sinh sn nh.
- Lai nc thi cng nghip nhim bn c trng ca cng nghip v cn x l cc
b trc kjhi x vo mng li that nc chung hoc vo ngun nc tytheo mc
x l.
1.1.3 Nc thi l nc ma
y l lai nc thi sau khi ma chy trn trn mt t v li ko cc cht cn b,
du m, khi i vo h thng that nc.
Nhng ni c mng li cng thot ring bit: mng li cng thot nc thi ring
vi mng li cng thot nc ma. Nc thi i v nh my x l gm: nc sinh hot,
nc cng nghip v nc ngm thm nhp, nu sau nhng trn ma ln khng c hin
tng ngp ng cc b, nu c nc ma c th trn qua np y cc h ga chy vo h
thng thot nc thi. Lng nc thm nhp do thm t nc ngm v nc ma c th
ln ti 470m3/ha.ngy.
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BI 1: NHNG VN CHUNG V X L NC THI 5 Ni c mng cng chung va thot nc thi va thot nc ma. y l trng hp
hu ht cc th trn, th x, thnh ph ca nc ta. Lng nc chy v nh my gm
nc thi sinh hot, nc thi cng nghip, nc ngm thm nhp v mt phn nc
ma.
Lu : Trong th: Nc thi sinh hot thng trn chung vi nc thi sn xut v
gi chung l nc thi th.
Nu tnh gn ng, nc thi th gm khong 50% l nc thi sinh hot, 14% l
cc loi nc thm, 36% l nc thi sn xut.
Lu lng nc thi th ph thuc rt nhiu vo iu kin kh hu v cc tnh cht
c trng ca thnh ph. Khong 65-85% lng nc cp cho 1 ngun tr thnh nc
thi. Lu lng v hm lng cc cht thi ca nc thi th thng dao ng trong
phm vi rt ln.
- Lu lng nc thi ca cc thnh ph nh bin ng t 20% QTB- 250%QTB
- Lu lng nc thi ca cc thnh ph ln bin ng t 50% QTB- 200%QTB
- Lu lng nc thi ln nht trong ngy vo lc 10-12h tra v thp nht vo lc
khong 5h sng.
- Lu lng v tnh cht nc thi th cn thay i theo ma, gia ngy lm vic v
ngy ngh trong tun cng cn c tnh n khi nh gi s bin ng lu lng v
nng cht gy nhim.
1.2 THNH PHN, TNH CHT CA NC THI VA CC DNG NHIM BN
1.2.1 Lu lng nc thi
- Xc nh lu lng nc thi c HTTN dng PP o lu lng ti ca x.
- Nu cha c HTTN hon chnh ta tnh theo tng loi sau:
1.2.1.1 Nc thi sinh hot
Nc thi sinh hot thng chim t 65% n 80% lng nc cp i qua ng h cc
h dn, cc c quan, bnh vin, trng hc, khu thng mi , khu gii tr, 65% p
dng cho ni nng, kh, nc cp dng c cho vic ti cy c.
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6 BI 1: NHNG VN CHUNG V X L NC THI Trong mt s trng hp phi da vo tiu chun thot nuc tnh ton s b lu
lng nc thi. (tham kho bng 1.5) sau y:
Bng 1.5. Tiu chun thi nc khu vc dn c
Stt Mc thit b v sinh trong cng trnh Tiu chun thi
(l/ngi.ng)
1 C h thng cp thot nc, c dng c v sinh, khng
c thit b tm
80 100
2 C h thng cp thot nc, c dng c v sinh v thit
b tm thng thng (vi sen)
110 140
3 C h thng cp thot nc, c dng c v sinh, c bn
tmv cp nc nng cc b
140 180
cc khu thng mi, c quan, trng hc, bnh bin, khu gii tr xa h thng cng
thot ca thnh ph, phi xy dng trm bm nc thi hay khu x l nc thi ring,
tiu chun thi nc c th tham kho bng 1.6, bng 1.7, bng 1.8. Tuy nhin, c s
thay i trong thc t iu kin nc ta.
Bng 1.6 Tiu chun thi nc t cc khu dch v thng mi
Ngun nc thi n v tnh Lu lng (l/n v tnh- ngy)
Khong dao ng Tr s tiu biu
Nh ga sn bay
Gara- t, sa xe
Qun bar
Kho hng ho
Khch sn
Hiu git l
Tim n
Siu th
C quan
Hnh khch
u xe
Khch hng
Ngi phc v
Nh v sinh
Nhn vin phc v
Khch
Ngi phc v
Cng nhn
My git
Ngi n
Ngi lm
Nhn vin
7,5 -15
26 -50
3,8 -19
38-60
1515-2270
30-45
151-212
26-49
26-60
1703-2460
7,5-15
26-50
26-60
11
38
11
50
1900
38
180
38
49
2080
11
38
49
Bng 1.7: Tiu chun thi nc t cc cng s
Ngun nc thi n v tnh
Lu lng (l/n v tnh-ngy)
Khong dao
ng
Tr s tiu
biu
Bnh vin
Ging bnh
Nhn vin phc v
473 -908
19 -56
625
38
-
BI 1: NHNG VN CHUNG V X L NC THI 7
Bnh vin tm thn
Nh t
Nh ngh
Trng i hc
Ging bnh
Nhn vin phc v
T nhn
Qun gio
Ngi trong nh iu dng
Sinh vin
284-530
19 -56
284 -530
19 -56
190 -455
56 -133
378
38
435
38
322
95
Bng 1.8 Tiu chun thi nc t cc khu gii tr
Ngun nc thi n v tnh Lu lng (l/n v tnh-ngy)
Khong dao ng Tr s tiu biu
Khu ngh mt c khch sn
mini
Khu ngh mt lu, tri, t
di ng
Qun c ph gii kht
Cm tri
Nh n
B bi
Nh ht
Khu trin lm, gii tr
Ngi
Ngi
Khch
Nhn vin phc v
Ngi
Xut n
Nhn vin
Ngi tm
Nhn vin
Gh ngi
Ngi tham quan
189 -265
30 -189
3,8 -11
30 -45
75 -150
15 -38
30 -189
19 -45
30 -45
7,5 -15
15 -30
227
151
7,5
38
113
26,5
151
38
38
11
19
Lu lng nc thi sinh hot:
Qtb = N.q
Qnmax = Qtb . Kng
Qs = Qtb /86400
Qsmax = Qs . Kc
Trong :
N : S dn c
q : Tiu chun thot nc
Kng :H s khng iu ha ngy H s khng iu ngy ca nc thi sinh hot khu
dn c ly Kng = 1,15 1,3
Kc : H s khng iu ha chung
H s khng iu ha chung Kc = Kng . Kh
Bng 1.9. H s khng iu ha chung ca nc thi sinh hot
Lu lng trung 5 10 20 50 100 300 500 1000 5000
-
8 BI 1: NHNG VN CHUNG V X L NC THI
bnh (lit/giy)
Kc max 2,5 2,1 1,9 1,7 1,6 1,55 1,5 1,47 1,44
Kc min 0,38 0,45 0,5 0,55 0,59 0,62 0,66 0,69 0,71
1.2.1.2 Nc thi cng nghip
Ph thuc vo quy m, tnh cht sn phm, quy trnh cng ngh ca tng nh my.
Lu lng sn xut c th dng cng thc sau y:
Q = qtc x P
Trong :
P : Cng sut sn phm ca nh my
qtc : Tiu chun (nh mc ) s dng nc cho sn xut. C th tham kho s liu
nh mc x thi ca nh my trong bng 1.10
Bng 1.10. Tiu chun thi nc ca mt s ngnh cng nghip
STT Ngnh sn xut nc thi/sn phm (qtc)
1 Ch bin m cao su 54 lit/tn sn phm crp
2 Ch bin thy sn 20 100 m3/tn
3 Ch bin nng sn 6 60 m3/tn nng sn
4 Ch bin tht 3 10 m3/tn sn phm
5 Thuc da 65 100 m3/tn da t
6 Git gi 33 lit/kg qun o
7 Ru bia 0,3 m3/gi la (36 lit)
8 C ph 22 m3/tn sn phm
9 Luyn du 3 m3/thng du th (150 l)
10 Luyn cn thp 0,1 0,8 m3/tn thp
11 Chn nui gia cm 15 25 lit/kg gia cm
12 Sn xut giy v bt giy 60 240 m3/tn sn phm
13 Ch bin m cao su (tinh) 25 m3/tn sn phm)
14 Ch bin m cao su (mu tp) 35 m3/tn sn phm)
15 Ch bin m cao su (ly tm) 18 m3/tn sn phm)
Ngoi ra trong x nghip cn c mt lng nc thi sinh hot rt ln nn vic xc
nh n cng c mt ngha v cng quan trng.
-
BI 1: NHNG VN CHUNG V X L NC THI 9 Tiu chun nc thi sinh hot ca cng nhn trong cc phn xng s3n xut c th
ly theo Bng 1.11
Bng 1.11. Tiu chun thot nc thi sinh hot trong cc phn xng sn xut
Loi phn xng Tiu chun thot nc
(l/ngi.ng)
Kh
Phn xng nng ta nhit
Phn xng thng
35
25
2,5
3,0
Lng nc tm cho cng nhn sau gi lm vic theo kp l 40 60 lit/ngi v thi
gian tm l 45 pht.
Lu lng nc thi trong cc x nghip cng nghip:
Qtb = (25N1 + 35N2)/1000, m3/ng
Qhmax = (25N3 + 35N4)/T.1000
Qsmax = Qhmax /3,6
S phn b lu lng nc thi sn xut theo ca kp c th ly theo phn trm lu
lng ngy nh trong bng 1.12
Bng 1.12. Phn b phn trm lu lng sn xut theo ca
Bui Lm vic 3 ca Lm vic 2 ca
Bui sng 40 50 50 65
Bui chiu 35 30 50 65
Bui m 20 25
C ngy 100 100
Ngoi ra khi khng c s liu c th ca tng nh my c th tnh lng nc thi
chung theo din tch ca khu cng nghip nh sau:
- KCN gm cc nh my SX ra sn phm th, t ngm nc, lng nc thi dao ng
t 9-14m3/ha.ngy.
- SX sn phm ngm nc trung bnh t 14-28m3/ha.ngy.
- Lng nc thi KCN tnh theo lng nc cp: 90-95%
1.2.1.3 Nc ma
ic xc nh lu lng nc ma kh phc tp. Rt nhiu cng trnh x l nc thi
sinh hot hin nay cha cp nhiu n vic xc nh lng ma. Ti liu ny trnh mt
phng php ng hc (phng php .) xc nh lu lng nc ma ti mt vng
bt k. Vic tnh ton mg li thot nc ma s cp trong mt ti liu khc ca tc
gi
-
10 BI 1: NHNG VN CHUNG V X L NC THI
A. Cc s liu c bn thit k h thng thot nc ma
1. Thi gian ma: L thi gian ko di ca mt trn ma tnh bng pht hoc gi. Thi
gian bt u cn ma c lng nc chy vo mng li nh hn lu lng tnh ton.
Hin tng ny gi l s chm tr ca dng chy nc ma, do nc ma phi mt
thi gian di chuyn t b mt lu vc n mng li thot nc. V vy, trn sut
chiu di on ng, lu lng lun nh hn lu lng ti a hin din cui on ng
tnh ton.
- Thi gian ma tnh ton:
ttt = tm + tr + to
Trong :
tm : Thi gian tp trung nc ma trn b mt t im xa nht n mng li
phutIiZ
Lntm ,
..
..5,13,05,03,0
6,06,0
Z,n,i : h s lp ph, h s nhm v dc b mt tp trung nc ma
I : cng ma, mm/pht
L : chiu di on nc chy
Cng thc xc nh tm p dng cho cc b mt tp trung nc ma c san nn
khng c rnh, lung, ...)
Lu : Tnh ton tm s b c th ly nh sau:
- Trong tiu khu khng c h thng thot nc ma: tm = 10 pht
- Trong tiu khu c h thng thot nc ma: tm = 05 pht
tr : Thi gian nc chy trong rnh: tr = 1,25. lr /vr (giy)
- lr, vr : chiu di (m) v vn tc (m/s) nc ma chy cui rnh
- 1,25 : h s tnh n s tng tc chy trong thi gian ma
to : Thi gian nc chy trong ng n tit din tnh ton:
to = M lo / vo (giy)
- lo, vo : chiu di, vn tc nc ma chy trong ng
- M : h s tnh n s chm tr ca dng chy nc ma
M = 2 : a hnh thot nc ma bng phng i < 0,01
M = 1,5 : a hnh thot nc ma c dc = 0,01 0,03
M = 1,2 : a hnh thot nc ma c dc > 0,03
-
BI 1: NHNG VN CHUNG V X L NC THI 11
2. Cng ma: l lng nc ma ri xung tnh trn mt n v din tch trong mt
n v thi gian. Cng ma c biu din di 2 hnh thc: theo lp nc v
theo th tch.
- Cng ma tnh theo lp nc l t s gia chiu cao lp nc v thi gian ma.
i = h/t (mm/pht)
- Cng ma tnh theo th tch l lng nc ma tnh bng l/s.ha
q = 166,7 i (l/s.ha)
- Cng ma c xc nh theo cng thc Lin x c:
Trong :
n,C : i lng ph thuc c im kh hu tng vng
q20 : Cng ma trong thi gian 20 pht vi chu k P= 1 nm
P : Chu k ma, nm
t : thi gian ma tnh ton, pht
- Cng ma c xc nh theo cng thc Trn Lit Vin:
n
n
bt
PCqbq
lg.120 20
Cc gi tr n, C, b tra trong bng phn b ma tng a phng
3. Chu k ma: L thi gian lp li mt trn ma c cng cng v thi gian ma.
n v tnh bng nm
4. Chu k trn cng (P): l thi gian c mt trn ma vt qu cng ma tnh ton
La chn P: + Khu dn c, thnh ph nh : 0,3 01 nm
+ Thnh ph ln, khu cng nghip: 01 03 nm
+ Khu vc c bit quan trng: 05 10 nm
Bng 1.13. Chu k trn cng i vi khu vc dn c
Loi cng iu kin lm vic ca cng
Thun li Trung bnh Bt li Rt bt li
Khu vc 0,25 0,35 0.5 1
Ph chnh 0,35 0,5 1 2
iu kin thun li:
a. Din tch lu vc khng ln hn 150 ha, a hnh bng phng, dc trung bnh ca
mt t 0,005 v nh hn
n
n
t
PCqq
lg.1.20 20
-
12 BI 1: NHNG VN CHUNG V X L NC THI
b. ng cng t theo ng phn thy hoc phn trn ca sn dc cch ng
phn thy khng qu 400m
iu kin trung bnh:
a. Din tch lu vc ln hn 150 ha, a hnh bng phng, dc trung bnh ca mt t
khong 0,005 v nh hn.
b. ng cng t pha thp ca sn dc, theo khe t nc, dc ca sn dc nh
hn hay bng 0,02, din tch lu vc khng qu 150 ha.
iu kin bt li:
a. ng cng t pha thp ca sn dc v din tch lu vc ln hn 150 ha.
b. ng cng t theo khe t nc ca sn dc, dc trung bnh ca sn dc ln
hn 0,02.
iu kin rt bt li: ng cng dng thot nc t mt ch trng
Bng 1.14. Gi tr P theo q20
c im vng thot nc ma Gi tr P khi q20 bng
50 70 70 90 90 100 > 100
a hnh phng, i< 0,006 khi:
F 150 ha
F > 150 ha
a hnh dc, i> 0,006 khi:
F 20 ha
F = 20 50 ha
F = 50 100 ha
F > 100 ha
0,25 0,33
0,33 0,50
0,33 0,5
0,5 1
2 3
5
0,33 0,5
0,5 1,5
0,5 1,5
1 2
3 5
5
0,5 1,5
1,5 2
1 2
1 3
5
10
2 3
4
3 4
5 10
10
10 20
Bng 1.15. Chu k trn cng i vi khu vc cng nghip
Hu qu do vic trn cng P (nm)
Qu trnh cng ngh khng b h hng
Qu trnh cng ngh b h hng
1 2
3 - 5
5. H s dng chy: L t s gia lng nc ma chy vo mng li thot nc v
lng nc ma ri xung.
= qc / qr
qc, qr: Lng nc ma ri trn din tch 1 ha v lng nc ma chy vo mng li
thot nc t 1 ha .
= Ztb . q0,2 . t0,1
Trong :
-
BI 1: NHNG VN CHUNG V X L NC THI 13
- q,t: cng ma (l/s.ha) v thi gian ma tnh ton (pht)
- Ztb:h s mt ph trung bnh ca ton lu vc
Khi din tch b mt khng (hoc t) thm nc ln hn 30% din tch lu vc th h
s dng chy cho php ly bng tb l i lng trung bnh chung ca h s dng chy
o v din tch b mt m khng ph thuc vo cng ma v thi gian ma.
Bng 1.16. bng xc nh h s dng chy o v h s lp ph b mt Z
Dng b mt H s dng chy o H s Z
Mi nh, mt ng btng 0,95 0,240
Mt ph dm, o, ng nha 0,6 0,224
ng lt cui, hc 0,45 0,145
Mt ph dm khng c vt liu kt dnh 0,4 0,125
ng si trong vn 0,35 0,09
Mt t 0,3 0,064
Mt c 0,15 0,038
B. Tnh ton nc ma
Gi thit rng thi gian ma chnh bng thi gian nc ma t im xa nht trong
lu vc chy n tit din tnh ton. Xc nh lu lng tnh ton nc ma cn c vo
thi gian tp trung nc ma c gi l phng php cng gii hn.
Qtt = . . q. F
Trong o:
F: din tch lu vc, ha
H s phn b ma ro l h s k n s phn phi ma khng ng u trn
ton lu vc
= qTB / qmax
3/2.001,01
1
F
Bng 1.17. Gi tr
Din tch lu vc, ha
-
14 BI 1: NHNG VN CHUNG V X L NC THI 20-400%: dn c 1000 ngi.
50-300%: dn c 10000 ngi.
80-200%: dn c 100000 ngi.
- Thnh ph ln th:
qhmax (1.25-1.5) qh
tb
qhtb (1.25-1.5) qh
min
1.2.3 Chn lu lng thit k
- Tun theo s quy hoch dn c (tng dn c, ), xy dng KCN mi, m rng mt
bng, .
- Ta c th chn nh sau:
1. Lu lng ngy TB: dng tnh ton
- Nng lng in tiu th
- Lng ha cht tiu th
- Lng cn bn cn x l
- Lng nc x ngun tip nhn
2. Lu lng gi max, min
- Mng li thot nc
- My bm ca trm bm nc thi
- Song chn rc
- B lng ct v b iu ha lu lng.
3. Khi c h s khng iu ha K 1.5 : Khng xy b iu ha. Ly Qtb ca cc gi: 6,
7, 11, 12, 18, 19 tnh cho cc cng trnh sinh hc, cc b lng.
1.2.4 Thnh phn, tnh cht nc thi
1.2.4.1 Thnh phn v tnh cht cn c trong nc thi
a. Tng hm lng cn (TS)
- Tng cc loi cn Hu C v V C dng l lng v ha tan (mg/l).
- xc nh: Ly mt th tch (V) nc thi em sy kh 103oC, sau em cn v
chia cho th tch (V) ta c TS
b. Cn hu c : C ngun gc
-
BI 1: NHNG VN CHUNG V X L NC THI 15
- Thc n ca ngi, ng vt
- Xc ng, thc vt
- Thnh phn ha hc: C, H, O, N, O, P, S.
- Dng tn ti ch yu: Protein, Carbonhydrate, cht bo,
- xc nh: Cn v em sy 550-600oC: VS (cn bay hi).
c. Cn v c
- L cn cn li sau khi sy 550oC (hay cn gi l tro). Ngun gc l cc mui
khong, ct, sn, .
d. Cn l lng (SS)
- L nhng cn c th quan st bng mt thng hay loi b bng cc phng php nh
lng, lc.
- xc nh ta ly mt (V) nc thi em lc qua giy lc, sy kh 150oC v em
cn (mg/l).
- SS:70% l HC, 30% l VC
e. Cn lng c
- Ly 1 lt nc thi cho vo ng lng c khc , lng tnh 30. o th tch cn lng
pha y ng nghim, kt qu ml cn lng / lt nc thi (ml/l) hay ml cn lng /
gam SS: Gi l ch s th tch: SVI = Vlng SS
f. Cn l lng dng keo
- L loi cn sau thi gian t 3-4h vn khng b lng y ng nghim (65% HC +
35% VC)
g. Cn ha tan
- C kch thc rt nh v lt qua giy lc (40% HC + 60% VC).
- V vy, khi thit k cng trnh x l nc thi l phi lm sao pht trin c cc VSV
hp th cn HC dng ha tan, keo, l lng thnh cn dng n nh d lng.
Ta c th hnh dung m hnh cn nh sau:
-
16 BI 1: NHNG VN CHUNG V X L NC THI
Hnh 1.1. S phn loi cn
1.2.4.2 Nhu cu oxy sinh ha BOD v nhu cu oxy ha hc COD
a. BOD (NOS): (mg/l)
L lng oxy cn thit cho VK pht trin oxy ha cc cht HC c trong nc thi.
y l thng s quan trng dng ch mc nhim bn nc thi bng cc cht HC v
dng tnh ton, thit k cng trnh x l bng pp sinh hc .
CCH XC NH BOD:
- Ly nc bo ha oxy, o DOb (mg). Ly (V) nc thi cho vo mu v cho vo t
sy 20oC, sau 5 ngy a ra o lng oxy cn li trong mu (DOsau)
BOD = DOb - DOsau
V (mg/l)
- phn hy hon ton (98%) th phi cn n 20 ngy cy (BOD20)
BOD5 = (0.68 - 0.7)BOD20
b. COD (NOH):
- L lng oxy cn thit oxy ha hon ton cc cht HC v mt phn cc cht V
c.
- Xc nh COD bng PP oxy ha mnh trong Mi trng acid (PP Bicromat)
- COD lun > BOD
- COD/BOD cng nh th XLSH cng d.
- Nc thi sinh hot c BOD ~ 0.86COD (NT cng nghip th thay i)
1.2.4.3 Oxy ha tan (DO)
- y l ch s quan trng trong x l SINH HC hiu kh (lun gi 1.5 _ 2mg/l).
-
BI 1: NHNG VN CHUNG V X L NC THI 17
- DO ph thuc vo nhit , p sut ca nc (nhit tng DO gim, p sut tng
DO tng).
- Nu k hiu thiu ht oxy: D
D = 0: oxy bo ha hon ton
D = 1: Thiu ht han ton nn khng c oxy.
- thiu ht oxy sau thi gian t: Dt = Do*10-K2t
Trong : Vi: K2: h s tc ha tan (ph thuc vo to, S, )
Ngun nc K2
10oC 15 oC 20 oC 25 oC
Khng c dng chy - 0.11 0.15 -
vchy
-
18 BI 1: NHNG VN CHUNG V X L NC THI
- nh gi s tn ti ca H+ trong nc thi. Ch tiu kh quan trng khi nghin cu x
l nc thi .
pH = -lg[H+]
- Qu trnh x l nc thi bng PP SH rt cn gi tr pH.
- Qu trnh XL hiu kh cn pH = (6.5-8.5). Tt nht l 6.8-7.4.
1.2.4.6 Hp cht Nit v Phospho
N l cht dinh dng quan trng trong qu trnh pht trin ca VSV trong cc cng
trnh XLSH. Trong nc thi tn ti 2 dng l NO2-v NO3-. NO2- l sn phm trung
gian ca qu trnh nitrt ha. Qu trnh ny bao gm 2 giai on:
2NH3 + 3O2 2HNO2 + 2H2O + Q
Sau :
2HNO2 + O2 2HNO3 + 2H2O + Q
Nh vy, NO2 v NO3 ch c th xut hin sau khi x l nc thi trong cng trnh
sinh ha: Biophin v Areten.
Phospho cng nh nit l cht dinh dng cho VK sng v pht trin trong cc cng
trnh x l nc thi. Tn ti ch yu PO43-.
C hai loi Nit v P nu vt qu gi tr no s gy ph dng ha.
Trong x l nc thi bng PP SH thng COD:N:P ~150:5:1
1.2.4.7 Cc hp cht v c trong nc thi sinh hot khng cn
phn tch, nhng ng lu l chlorite v sulphate
- Chlorite khng bin i trong qu trnh x l, nhng n cho chng ta nhn bit nc
thi sinh hot c b pha trn nc thi CN hay khng.
- Sulphate trong iu kin him kh s sinh H2S rt hi.
- Nc thi CN cha mt hm lng cht v c, c c cc KL nng. Nn cn xc nh v
loi tr cc b trc khi cho vo mng li chung.
1.2.4.8 Thnh phn VS
Nitroza
Nitrosomona
s
VK
Nitrobacter
-
BI 1: NHNG VN CHUNG V X L NC THI 19 Nc thi c cha mt lng ln VK, VR, nm, ru to, giun sn, . nh gi mc
nhim bn bi VK, ngi ta nh gi qua mt loi VK ng rut: Coli.
- Coli index (Coli chun ) l i lng dng tnh ton s lng trc khun c cha
trong 1 lt nc thi.
- Tr s Coli (Colitit) l th tch nc nh nht (ml) c cha mt trc khun. VD: ni
rng Colitit = 400 tc l trong 400 ml nc thi cha 1 trc khun.
1.2.4.9 Nhit nc thi
y l i lng nh hng trc tip n cng trnh x l nc thi bng PP sinh hc.
Nhit khng ch nh hng n thi gian chuyn ha ca SV m cn tc ng n qu
trnh hp thu kh oxy vo nc thi v qu trnh lng bng cn b lng 2.
Bin thin nhit P ph thuc vo nhit :
rT = r20 x (T 20)
Trong :
rT: nhit phn ng & To (K)
r20: nhit phn ng & 20oC
: h s hot nhit (1.02-1.09)
Nng thch hp cho x l SH: 30-35oC
1.3 BO V NGUN NC KHI B NHIM BN, KH NNG T LM SCH CA NGUN NC
1.3.1 Du hiu ngun nc nhim bn. Kh nng t lm
sch ca ngun nc
Du hiu:
- Xut hin cht ni ln trn b mt v cn lng y.
- Thay i tnh cht vt l (Mu sc, mi v).
- Thay i thnh phn ha hc (s lng CHC, phn ng, cht khong v cht c ).
- Lng oxy ha tan gim gim xung
-
20 BI 1: NHNG VN CHUNG V X L NC THI
- Thay i hnh dng v s lng vi trng gy bnh.
Ngun nc b nhim bn s dn n tnh trng mt cn bng ST. Do , ngun nc
t iu chnh ti lp li trng thi ban u gi l qu trnh t lm sch (QTTLS).
Hnh 1.3. Phn chia cc vng ca dng chy theo kh nng t lm sch ca
ngun nc
QTTLS chia 2 giai an: xo trn v t lm sch.
S tng quan gia lu lng ngun v lu lng nc thi l yu t quan trng trong
qu trnh t lm sch: gi l h s pha trn n:
n = Q + q
q =
C - Cng Cgh - Cng
Vi:
- C: hm lng bn ca nc thi
- Cng: hm lng bn ca ngun
- Cgh: hm lng bn sau khi ha trn (yu cu)
- Q: lu lng nc ngun
- q: lu lng nc thi x vo ngun
-
BI 1: NHNG VN CHUNG V X L NC THI 21 S ha tan oxy (DO) cng l yu t quan h mt thit n QTTLS.
Thc t th khng phi tt c lu lng nc ngun tham gia vo qu trnh xo trn
m ch mt phn no m thi. Phn nc ngun tham gia vo qu trnh c c
trng bi h s xo trn. Cng thc trn c vit thnh:
q
qQn
.
: H s ph thuc c tnh thy lc v hnh dng dng chy ca nc ngun:
= 3
3
1
1
l
l
eq
Q
e
Trong :
: Khong cch t ca x nc thi n mt ct tnh ton (m)
: H s c tnh n nh hng thy lc
= 3 E
q
Ca x xa b )
E : H s khuych tn
E = 200
. tbtb HV
mc
HVgE tbtb
2
..
VTB: Vn tc dng chy trung bnh
HTB: Chiu su trung bnh dng chy
m : T l gia vn tc dng chy nc ngun v nc thi qua ming x
c: nng nhim bn ca nc h cha
Lu : T cng thc trn ta thy h s tin ti n v khi khong cch l di ra v
cng. Mt khong cch nh th trong thc t l khng c. Chnh v vy ngi ta ch xc
nh cho mt khong cch no nc ngun c th tham gia c 70 80% lu
lng vo qu trnh xo trn i vi nhng ngun nc nh v 0.25 0.3 i vi nhng
ngun nc trung bnh v ln. Khong cch l c th tham kho bng 1.18.
Bng 1.18 . Bng dng xc nh khong cch l
-
22 BI 1: NHNG VN CHUNG V X L NC THI
T l gia lu lng nc ngun v nc thi Q:q
Khong cch (km) t ca x ti mt ct xo trn hon ton (im tnh ton), khi lu lng nc ngun, (m3/h)
< 5 5 - 50 50 - 500 >500
1:1 - 5:1 0.54 0.72 0.9 1.35
5:1 25:1 0.54 4.0 6 8
25:1 125:1 10 12 15 20
125:1 600:1 25 30 35 50
> 600 50 60 70 100
1.3.2 Nguyn tc x nc thi vo ngun
Sau khi x l, vic x vo ngun phi tun theo lut bo v ngun nc:
Bng 1.19. Bng cc gi tr cho php tng ln sau qu trnh x thi
H cha
Cht nhim bn
Loi 1 2 3
1. SS Sau khi x nc thi th SS trong ngun tng ln cho php
0.25 (mg/l) 0.75 (mg/l) 1.5 (mg/l)
2. Mi, v Sau khi x nc thi th nc ngun khng mi
3. DO D > 4 mg/l
4. BOD20 Sau khi x th BOD20 khng vt qu
3 (mg/l) 6 (mg/l) Khng quy nh
5. P Khng lm thay i P: 5.5 < pH < 8.5
6. Mu sc Khng c mu khi nhn qua ct nc cao
20 cm 10 cm 5 cm
7. VK Cm x nc thi c VK gy bnh
8. Cht c Nc thi x vo khng c tnh c hi
Ghi ch:
- Loi 1: Cp nc th, XN ch bin thc phm
- Loi 2: Cp cho Cng nghip , dng chn nui c, tm git,
- Loi 3: Ti tiu, chn nui thy sn
1.3.3 Xc nh mc x l nc thi
- Khi b cc cht nhim trong nc thi khng phi lm cho chng bng khng m
phi n mc cho php x vo ngun (TC x thi).
- Cng trnh x l tt hay khng da vo 2 yu t:
Hiu qu x l (mc x l).
-
BI 1: NHNG VN CHUNG V X L NC THI 23 Nin hn s dng.
- C 2 cch xc nh mc x l:
Xc nh mc x l theo SS
Xc nh mc x l theo BOD
1.3.3.1 Theo SS
Hm lng cht l lng cho php trong nc thi x vo ngun c xc nh nh
sau:
C2 = p( . Q
q + 1) + Cng
Trong :
- C2: Hm lng cht l lng cho php trong nc thi x vo ngun
- p: Hm lng cht l lng tng cho php trong nc ngun sau xo trn (g/m3) (TC
SS)
- Q: Lu lng nc ngun (m3/h)
- q: Lu lng nc thi (m3/h)
- Cng: Hm lng cht l lng trong nc ngun (g/m3)
- : H s ph thuc c tnh thy lc
Eo = 100% (C1 - C2) C1
1.3.3.2 Theo BOD
BOD ca nc thi cho php thi vo ngun:
tk
th
tk
tk
ngtk
th LLL
q
QL
11
'1
1 1010
10
102
Vi:
- Lng: BOD ngun
- k1, k1: Hng s tc tiu th oxy ca nc thi v nc ngun
- k1: Theo bng ph thuc nhit
Bng 1.20. Bng xc nh k1
To, oC 10 15 20 25 30
k1 0.063 0.08 0.1 0.126 0.158
- k1 : Theo bng sau:
-
24 BI 1: NHNG VN CHUNG V X L NC THI
Bng 1.21. xc nh k1
c tnh ngun nc Gi tr k1, vi nhit nc ngun
100C 1050C 200C 250C
Ngun nc khng c dng chy hoc chy chm
0.11 0.15
Ngun nc c tc dng chy < 0.5 m/s
0.17 0.185 0.02 0.215
Ngun nc vi dng chy mnh 0.425 0.46 0.05 0.54
Ngun nc nh vi dng chy mnh 0.684 0.74 0.08 0.865
- t: Thi gian xo trn = 1
- Lth: BOD ti hn ca hn hp nc thi v ngun
Suy ra: Mc cn thit x l nc thi: Eo = Lo - L2
Lo . 100%
V d: Xc nh mc cn thit x l nc thi vi lu lng q= 0.8 m3/s, BOD ban
u Lo = 261 mg/l, hm lng cht l lng C1 = 271.6 mg/l. Lu lng nc sng Q =
14 m3/s, tc dng chy VTB = 0.4 m/s, chiu su trung bnh HTB = 2 m, nng cht
l lng Cng = 12 mg/l, BOD l Lng = 2 mg/l. Khong cch t ca x ti mt ct tnh ton
l L = 30 km, nhit trung bnh ma h to = 15oC. Thi gian ti hn cho bng 2.6 (h).
Bi gii
- Theo SS
E = (VTB.HTB)/200 = (0.4 x 2)/200 = 0.004
= 1.2 x 1.5 3 0.004
0.8 = 0.321
= 1 -e- 0.32
330000
1 + 14
0.8 e- 0.32
330000
= 0.85
C2 = 0.25 [0.85(14/0.8) + 1] + 12 =15.98 (mg/l)
Eo = [(271.6 15.98)/ 271.6]. 100% = 93.5 (%)
- Theo BOD
L2 = 0.85 14
0.8 (
3
10- 0.08x2.6 - 2
10- 0.185x2.6
10- 0.08x2.6) +
3
10- 0.08x2.6 = 28.69 (mg/l)
-
BI 1: NHNG VN CHUNG V X L NC THI 25
Eo = [(261 28.69)/ 261]. 100% = 89 (%)
1.4 S CNG NGH X L NC THI
1.4.1 C s la chn cng trnh x l nc thi:
Trong vic quyt nh xy dng cng trnh x l nc thi, 3 nhn t chnh quan trng
c gi l 3E, gm: Mi trng (Environment), K thut (Engineering), Kinh t
(Economic) cn phi hi ha vi nhau.
Khi kho st thit k mt t hp cng trnh, tin trnh xem xt theo s sau:
Hnh 1.4. Cc bc thit k cng trnh x l nc thi
Trong cc bc trnh by trong s , vic chn la qui trnh x l thit k cng
trnh mang tnh cht quyt nh quan trng. Mt cng trnh c thit k, xy dng v
vn hnh hiu qu ph thuc vo nhiu yu t khc nh k nng ca k s thit k,
chin lc ca nh qun l, kh nng u t xy dng cng trnh v trang b cc thit b
my mc, cht lng thi cng v lp t my mc v chi ph xy dng v vn hnh bo
dng.
- Ngoi ra ta c th da vo mc tiu x l la chn cng trnh cho ph hp.
-
26 BI 1: NHNG VN CHUNG V X L NC THI VD:
Tch rn khi lng: song chn rc, lng, lc
Tch lng khi rn: nn bn, tch nc khi bn
Tch lng khi lng: tch du m
Tch kh khi lng: tch kh ammonia, kh sinh hc
Cht hu c: hiu kh (bn hot tnh, sinh trng bm dnh), k kh (UASB)
Cht dinh dng: kh Nit, Photpho
Bng 1.22. Tng quan v cng ngh v phng php x l nc thi
Cng ngh
x l
Phng php
x l
Cng trnh x l Mc tiu x l
X l
s b
+ Ha L
+ Ha hc
- Tuyn ni
- Hp ph
- Keo t...
- Oxy ha
- Trung ha
- Tch cc cht l lng v
kh mu
- Trung ha v kh c
nc thi
X l
tp trung
+ C hc
+ Sinh hc
+ Kh trng
+ X l bn cn
- Song chn rc
- B chn rc
- B lng t I
- H sinh vt
- Cnh ng lc, ti
- Knh oxy ha
- Aeroten
- B lc sinh hc
- B lng t II
- Trm trn Clor
- Mng trn
- B tip xc
- B metan
- Sn phi bn
- Trm x l c hc bn cn
- Tch cc tp cht rn v
cn l lng
- Tch cc cht hu c
dng l lng v ha tan
- Kh trng trc khi x ra
ngun
- n nh v lm kh ngun
cn
X l
trit
+ C hc
+ Sinh hc
+ Ha hc
- B lc ct
- B aeroten bc II
- B lc sinh hc bc II
- H sinh vt
- B kh nitrat
- B oxy ha
- Tch cc cht l lng
- Kh nit v phtpho
- Kh nit ,phtpho v cc
cht khc
-
BI 1: NHNG VN CHUNG V X L NC THI 27
1.4.2 Dy chuyn cng ngh trm x l nc thi:
Mt dy chuyn x l c th bao gm 5 khi sau:
a. Khi x l c hc: tch cc cht khng ha tan v 1 phn dng keo (song chn rc,
lng ct, lng, vt du lc, )
b. Khi x l ha hc (thng t sau cc cng trnh x l c hc, trc cng trnh x l
sinh hc): bin i ha hc v kt hp c hc (keo t, hp ph, hp th, )
c. Khi x l sinh hc: dng VSV oxy ha cht bn hu c dng keo v ha tan (iu
kin t nhin v nhn to: cnh ng ti,h sinh hc, mng oxy ha, cnh ng
ti, b lc sinh hc, bn hot tnh, )
d. Khi x l cn: x l cc cht thi to thnh trong qu trnh x l c hc, ho hc,
sinh hc (b metan, sn phi bn, trm x l c hc bn cn)
e. Khi kh trng: kh trng trc khi x ra ngun (trm trn Clor, mng trn, b tip
xc)
VD: S phn khi x l nc thi sinh hot:
Hnh 1.5. S phn khi x l nc thi sinh hot
-
28 BI 1: NHNG VN CHUNG V X L NC THI
1.4.3 Gii thiu 1 s dy chuyn x l nc thi:
1. XLNT sinh hot:
- Nc thi c a qua song chn rc loi b tp cht l lng th c th lm nght
thit b
- Sau NT c a vo b vt du m tch du m ra khi nc. Trn hnh l m
hnh b lng ngang kt hp b vt du m nn ta khng cn x dng b lng t I.
- B aeroten s x l cc cht hu c phn hy sinh hc c trong nc thi.
- B lng 2 dng lng bn sinh hc c trong nc thi sau qu trnh x l b
aeroten.
- Trc khi x ra ngun ngun tip nhn, nc thi c a vo b tip xc chlorine
kh trng.
- Lng bn pht sinh c a vo b lng bn tch nc v bn trc khi a vo
b metan x l cn hu c.
-
BI 1: NHNG VN CHUNG V X L NC THI 29
2. XLNT bnh vin:
Hnh 1.6. S h thng XLNT bnh vin
- B iu ha: iu hoa s bin thin ca lu lng/cng cht hu c.
- B sinh hc tip xc va b lng: Kh nhng cht hu c phn hy sinh hc (BOD) va
cn l lng (SS).
- B sinh hc tip xc c lam thong bi my thi thi kh.
- Bn tun hoan: duy tr mt sinh khi cao
- Bn d: bun d c thi n h thng x l bun va thi b.
- Trc khi x ra ngun ngun tip nhn, nc thi c a vo b tip xc chlorine
kh trng.
-
30 BI 1: NHNG VN CHUNG V X L NC THI
3. XLNT dt nhum:
Hnh 1.7. S h thng XLNT dt nhum
- Keo t-to bng: gip cho vic tp hp ca cc ht cn nh thnh cc ht cn ln hn
c th tch ra bng lng trng lc
B keo t to bng nu nh trn hnh l khng ph hp v cht l lng qua b hiu
kh v b lng c x l gn ht.B keo t to bng phi t sau b iu ha hiu
qu x l t cao nht.
-
BI 1: NHNG VN CHUNG V X L NC THI 31
B
m a
p l
c
On
g t
c
ha
y
On
g t
c
ha
y
On
g t
c
ha
y
On
g t
c
ha
y
On
g t
c
ha
y
On
g t
c
ha
y
Ho thu nc
a x b x c
6 x 4 x 3 (m)
Be ieu Hoa a x b x c
14.1 x 9 x 4.8(m)
Be Tao Bong x b x c
10.6 x 2.5 x 1.8 (m)
Be Lang Li Tam I D x c
11 x 4.7 (m)
Be Aeroten a x b x c
16.5 x 7 x 4.5 (m)
Be Lang Li Tam II D x c
20.6 x 4.7(m)
Ho Tiep Xuc a x b x c
6 x 4.4 x 3.3 (m)
Be
P
ha
n
ng
a
x
b
x
c
1.8
x
1
.2
5 x
0
.6
(m
)
Mat at-3,74(m)
Mat at
0(m)
-0.8(m)
-2.0(m)-2.4(m)
-2.0(m)
-1.2(m)
+3.7(m)
+1.9(m)
+2.4(m)
+1.8(m)
+2.4(m)
+1.8(m)+2.2(m)
Hnh 1.8. H thng x l nc thi nh my giy
Hnh 1.9. H thng x l nc thi Bnh vin
-
32 BI 1: NHNG VN CHUNG V X L NC THI
NC THAI VAO
XA RA NGUON
TEN CONG TRNH
KCH THC
(Dai*Rong*Cao), m
HAM BM
4*2,5*3,8
BE IEU HOA BE LANG I BE AEROTANK BE LANG II BE KH TRUNG
10*5,3*3,5D=4
H=6,411*7*4,4
D=4,8
H=7,23*1,3*2,3
+ 2500+ 2000
+ 3000
+ 2000
+ 1000
- 3800
-1000
-4400
-1300
-5200
-1300
NC THAI VAO
XA RA NGUON
TEN CONG TRNH
KCH THC
(Dai*Rong*Cao), m
HAM BM
2,5*2,2*3,2
BE IEU HOA BE LANG I BE UASB BE AEROTANK BE LANG II BE KH TRUNG
15*5*2,7D=2,87
H=5,5156*4*3,3 19,1*4*5
D=4,7
H=5,253*2,08*2,3
+ 200
+ 1700+ 1500
+ 3300
+ 3000
+ 1400
+ 1000
- 3000
-1000
-4015
-1300
-3850
-1300
Hnh 1.10. H thng x l nc thi sinh hot
Hnh 1.11. H thng x l nc thi nh my thc phm
-
BI 1: NHNG VN CHUNG V X L NC THI 33
BE NEN BUN
D x H = 5 x 4,4
BE X LY SINH HOC
30 x 10 x 5
BE LANG NGANG
15 x 4 x 2,5
BE KEO TU, TAO BONG
(MOI NGAN
2,3 x 2,3 x 2)
BE TUYEN NOI
& IEU HOA
D x H = 7,4 x 4
ONG KHONG AP
ONG KHONG AP
BM
AP LC
BM
AP LC
TRAM BM
2 x 2,8 x 2
0.000.00
ng hoa chat
ng bun
CHU THCH:
THUNG PHA
DUNH DCH
C-Polymer
MAY EP BUN
NC SACH
THUNG PHA
DUNH DCH
NaOH
THUNG PHA
DUNH DCH
PAC
THUNG PHA
DUNH DCH
Al2(SO4)3
C
B A
THANH GAT BUN
KENH THAM LNG
Hnh 1.12. H thng x l nc thi nh my vifon
-
34 BI 2: X L NC THI BNG PHNG PHP C HC
BI 2: X L NC THI BNG
PHNG PHP C HC
2.1 KHI NIM V PHNG PHP X L NC THI BNG PHNG PHP C HC
Phng php ny c s dng tch cc tp cht khng ha tan v mt phn cc
cht dng keo ra khi nc thi. Cc cng trnh x l c hc bao gm:
2.1.1 Thit b chn rc:
- Thit b chn rc c th l 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.
2.1.2 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.
-
BI 2: X L NC THI BNG PHNG PHP C HC 35
2.1.3 B iu ha:
L n v dng khc phc cc vn sinh ra do s bin ng v lu lng v ti
lng dng vo, m bo hiu qu ca cc cng trnh x l sau, m bo u ra sau x
l, gim chi ph v kch thc ca cc thit b sau ny.
C 2 loi b iu ha:
- B iu ha lu lng
- B iu ha lu lng v cht lng
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.
2.1.4 B lng ct:
Nhim v ca b lng ct l loi b cn th, nmg nh: ct, si, mnh thy tinh,
mnh kim loi, tro, than vn nhm bo v cc thit b c kh d b mi mn, gim cn
nng cc cng on x l sau.
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.
-
36 BI 2: X L NC THI BNG PHNG PHP C HC
2.1.5 B lng:
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).
2.1.6 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 xui
2.1.7 Tuyn ni, vt du m
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.
-
BI 2: X L NC THI BNG PHNG PHP C HC 37
Bng 2.1. 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
2.2 TNH TON THIT K CC CNG TRNH C HC
2.2.1 Song chn rc
SCR l cng trnh x l s b nhm loi b mt lng rc bn th chun b cho x l
nc thi sau . SCR bao gm cc thanh an sp xp cnh nhau. Khong cch gia cc
thanh gi l khe h (mt li) v k hiu l b.
Ta c th phn bit cc loi SCR nh sau:
- SCR th: b = 30 200mm.
- SCR c tinh: b = 5 25mm.
- SCR c nh v di ng.
- SCR th cng v c gii.
-
38 BI 2: X L NC THI BNG PHNG PHP C HC
TNH TON
Khong cch gia cc thanh b = 16 25mm.
- Gc nghing = 60 - 900.
- Vn tc trung bnh qua cc khe: v = 0,6 - 1 m/s
- S khe h gia cc thanh
zkvhb
qn
.. 1
max
kz: h s tnh n s thu hp dng chy: 1.05
qmax : lu lng ln nht
- Chiu di tng cng ca SCR: Bs = s (n - 1) + b.n
(s: chiu dy song chn : 8 10 mm)
- Chiu di on knh m rng trc SCR:
tg
BBl ks
21
( =15-200)
- Chiu di on thu hp sau: l2 = 0,5l1 (m)
-
BI 2: X L NC THI BNG PHNG PHP C HC 39
- Tn tht p lc qua SCR:
+ : h s tn tht cc b: = (s/b)4/3sin.
+ : h s ph thuc hnh dng thanh an:
= 2,42 1,83 1,67 1,97 0,92
K: h s tnh ti s tng tn tht p lc do rc mc vo SCR: K = 3.
- Lng rc c gi li:
Wr = a.Ntt /365.1000 (m3/ng.).
+ a: lng rc tnh cho 1 ngi/nm : 5 6 l/ngi.nm.
+ Dn s tnh ton: N = Q/q.
+ q: tiu chun thot nc:
- Mt s c tnh ca SCR:
+ m rc: 80%.
+ tro : 7 8 %.
+ Trng lng th tch 750 kg/m3.
V d p dng: Tnh ton thit k song chn rc ca mt cng trnh x l nc vi
cc thong s nh sau: lu lng trung bnh QTBng = 300 m3/ngy.
- Lu lng nc thi theo gi ln nht:
Qmaxh = QTB
h . kh = 12,5 * 2,2 = 31,25 (m3/h)
Vi kh l h s vt ti theo gi ln nht (k = 1,5 3,5), chn k=2,5.
- Chn loi song chn c kch thc khe h b =16 mm.
- Tit din song chn hnh ch nht c kch thc: s x l = 8 x 50 mm.
a. S lng khe h
Kg
vhs .
2
2
max
-
40 BI 2: X L NC THI BNG PHNG PHP C HC
Chn s khe l 10 s song chn l 9.
Trong :
n : s khe h.
Qmax : lu lng ln nht ca nc thi, (m/s).
vs : tc nc qua khe song chn, chn vs = 0,6 m/s.
kz : h s tnh n hin tng thu hp dng chy, chn kz = 1,05
b. B rng thit k song chn rc
Chn Bs = 0,3 m.
Trong :
- s : b dy ca thanh song chn, thng ly s = 0,008
c. Tn tht p lc qua song chn rc
Trong :
- vmax :vn tc nc thi trc song chn ng vi Qmax , vmax = 0,6.
- k :h s tnh n s tng tn tht p lc do rc bm, k = 2-3. Chn k = 2.
- : h s tn tht p lc cc b, c xc nh theo cng thc:
Vi: : gc nghing dt song chn rc, chn = 600.
: h s ph thuc hnh dng thnh an, = 2,42
d. Chiu di phn m rng trc SCR
Chn L1 = 0,2
Trong :
khekhbv
Qn z
ls
498,905,11,0016,06,0
1068,8 3max
mnbnsBs 232,010016,0110008,01
kg
vhs
2
2
max
83,060sin016,0
008,042,2sin 0
4/34/3
b
s
cmmhs 505,03
81,92
6,083,0
2
mtgtg
BBL ks 13,0
202
2,03,0
2 01
-
BI 2: X L NC THI BNG PHNG PHP C HC 41 Bs : chiu rng song chn.
Bk : b rng mng dn, chn Bk = 0,2m.
: gc nghin ch m rng, thng ly = 200.
e. Chiu di phn m rng sau SCR
f. Chiu di xy dng mng t SCR
Trong :
Ls : chiu di phn mng t song chn rc, L = 1,5m
g. Chiu su xy dng mng t SCR
Trong :
hmax = hl : y ng vi ch Qmax.
hs : tn tht p lc qua song chn.
0,5 : khang cch gia ct sn nh t SCR v mc nc cao nht.
Bng 2.2. Tm tt thng s thit k mng v song chn rc
STT Tn thng s n v S lng
1 Chiu di mng (L) m 1,8
2 Chiu rng mng (Bs) m 0,3
3 Chiu su mng (H) m 0,7
4 S thanh song chn Thanh 9
5 S khe (n) Khe 10
6 Kch thc khe (b) mm 16
7 B rng thanh (s) mm 8
8 Chiu di thanh (l) mm 50
2.2.2 B lng ct
B lng ct thng dng lng gi nhng ht cn ln c cha trong nc thi (chnh
l ct). C nhiu loi 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.
mLL 1,02,05,05,0 12
mLLLL s 8,15,11,02,021
mhhH s 65,05,0max
-
42 BI 2: X L NC THI BNG PHNG PHP C HC C bn loi b lng ct chnh: b lng ct theo chiu chuyn ng ngang ca dng
chy, b lng ct ng, b lng ct c sc kh( lm thong) hoc b lng ct c dng
chy xoy (tip tuyn).
Hnh 2.5. Cng trnh mng lng ct
2.2.2.1 B lng ct ngang
B lng ct ngang nc chy thng thng c h thu cn u b. Ct c co v
h thu bng co st v ly ra bng bm phun tia.
TNH TON
Chiu di ca b:
L = vmax.t (t = 30 - > 60s)
-
BI 2: X L NC THI BNG PHNG PHP C HC 43
=
ku
hv
o
m 11000
- Vmax : vn tc khi Qmax: 0,3 m/s.
- k: h s ly ph thuc u0.
o u0 = 18mm/s: k = 1,7.
o u0 = 24 m/s: k = 1,3. (ng knh ht ct thng 0,2 0,25 mm).
- h1: chiu su cng tc ca b: 0,25 1 m.
- u0 = ln thu lc ca ht ct vi ng knh 0,2 0,25 gi li trong b: u0 =
18 24 mm/s.
- Tit din t ca b : mv
QF max
- Chiu rng ca b :. 1.hv
qb
S ngn trong b: 1.hb
Fn
Vn tc ln nht: vmax 0,15 m/s.
Th tch ct trong b: 1000
.. TpNW ttc
- Ntt dn s tnh ton.
- p: lng ct vi m 60%, 0,02 l/ngi. ng..
- T: thi gian gia 2 ln x ct khi b : 2 4 ngy.
Chiu su lp cn ct: nbL
Wh c
..2
Chiu su tng cng: H xd = h1 + h2 + h3. (h3 = 0,2 0,4 m: chiu cao bo v t
nc n tng).
2.2.2.2 B lng ct ng:
-
44 BI 2: X L NC THI BNG PHNG PHP C HC B lng ct ng c xy dng theo nguyn tc nc thi dn theo ng tip tuyn
vi phn di hnh tr vo b. Dng chy xoy vng theo trc, tnh tin i ln. Cc ht
ct b ri dn v y phu v c thu ra ngoi:
TNH TON
- Din tch tit din ngang: vn
QF
.
max
- Chiu cao cng tc: h1 = v.t.
- Chiu su tng cng: H = h1+ h2 + h3 + h4.
- = h1+ 0,5+ h3 + h4.
- Nu trn :
FD
4
- Nu vung : FD
- Tc nc : v = 0,4 m/s.
- Thi gian lu: t = 2 3,5 pht.
2.2.2.3 B lng ct tip tuyn
C mt hnh trn. Mng dn nc vo tip tuyn vi b. Chu tc dng ca 2 lc, lc
bn thn P, v lc ly tm.
- Ti trng nc b mt : 100m3/m2.h.
- Tc nc trong mng: 0,8 0,6 m/s.
- Hiu qu gi ct: 90%.
- h D/2.
-
BI 2: X L NC THI BNG PHNG PHP C HC 45
2.2.2.4 B lng ct lm thong
B lng ct li ny thit k theo quan st chuyn ng ca cht lng xoy trn lm
cc ht rn trong cht lng tch ly li, nht l cc ht ct c ng knh ln hn 0,2mm,
thi gian lu li trong b khong 2-5 pht ti thi im c lu lng cc i. H thu ct
c b tr di y ng dn chng 0,9m di cc ng thi kh. Cc ng thi kh c
t v tr cch y b chng 0,45 0,6m.
L bc pht trin ca b lng ct tip tuyn. Nh thi kh m dng chy nc thi
trong b va quay va tnh tin to nn chuyn ng xoc c.
TNH TON
Hiu sut 90 95%.
ng knh ng thi kh: 2,5 6 mm.
Din tch tit din ngang: tvn
QF
.
max
.
-
46 BI 2: X L NC THI BNG PHNG PHP C HC
- vt: vn tc thng: 0,01 0,1 m/s.
- n: s ngn ca b.
Chiu su cng tc: t
o
t
o
v
u
b
h
v
ubh 11
.
- Chiu rng b b.
- uo : ln thu lc u0 ph thuc vo kch thc d ca ht ct theo bng di
y:
Bng 2.3. ln thu lc u0 ph thuc vo kch thc d ca ht ct
d(m) 0.1 0.12 0.15 0.2 0.3 0.4
uo(mm/s) 5.12 7.27 11.2 17.2 29.1 40.07
- Thi gian lu 1 vng: vv
bt 2.11
(vv: vn tc vng theo chu vi tit din ngang: 0,25 0,3 m/s.)
- Thi gian nc lu li: t = 1,1 .m.t1.
(m: s vng nc trong 1 b: m = 1/ lg(1 2h/H).)
- Chiu di ca b L = vt . t.
- Lng khng kh cn thit: Lk = I .F.
(I: cng kh: 25m3/m2.h.)
V d p dng: Tnh b lng ct ngang cho mt cng trnh x l nc thi vi cng
sut 417m3/h, hm lng SS = 254mg/l, COD
Chiu di ca b lng ct ngang c xc nh theo cng thc:
oU
vHKL max
***1000
Trong :
- K: h s ph thuc v loi b lng ct v th thy lc ca ht ct, K = 1,3
- H: su tnh ton ca b lng ct, H = 0,25 1m, chn H = 0,3m
- vmax: tc ln nht ca nc thi trong b lng ct ngang, vmax = 0,3 m/s.
- Uo = th thy lc ca ht ct, Uo = 18,7 24,2 mm/s. ng vi ng knh ca ht
ct d = 0,25 mm. Chn Uo = 24,2 mm/s.
Vy:
Chiu rng ca b lng ct ngang:
-
BI 2: X L NC THI BNG PHNG PHP C HC 47
Trong :
- Qmax: Lu lng ln nht giy, Qmax = 417 m3/h = 116 l/s = 0,116 m3/s
- vmax = 0,3 m/s
- H = 0,3 m
Chn 4 b lng ct ngang dng mng.
Vy :
Chiu rng mi ngn l:
Chiu rng mng:
Trong :
- B = 1,3m
- v = 0,3m
- m : h s lu lng ca ca trn ph thuc v gc ti. Chn g ti ,
chn m = 0,352.
- Qmax = 0,116 m3/s.
- K = 1,3.
Vy:
=0,2m
chnh y:
Trong :
Qmax = 0,116 m3/s
B = 1,3.
v = 0,3m/s.
Hv
QB
*max
max
2/33/2
max 1
1
2
K
K
Q
Bv
gm
Bvb
1cot,450 ag
2/33/2
3,11
3,11
116,0
3,0*3,1
81,9*2352,0
3,0*3,1
b
3/2
3/2max
1.
K
KK
Bv
QP
-
48 BI 2: X L NC THI BNG PHNG PHP C HC K = Qmin/Qmax = 167/417 = 0,4
Vy:
= 0,2m
Th tch phn cha cn ca b lng ct ngang:
1000
* otb qQW
Trong :
- Qtb = 4000 m3/ng
- q0: lng ct trong 1000 m3 nc thi, q0 = 0,15 m
3 ct/1000 m3 nc thi
- Vy:
1000
15,0*4000W = 0,6 m
3/ngay.d
Phn lng ct c b tr pha trc ca b lng ct ngang. Trn mt bng c dng
hnh vung, kch thc 1,1 x 1,1m, su H + 0,64m = 0,3 + 0,64 = 0,94m
Phn lp m rt nc c su 0,64m.
Hm lng cht l lng, COD v BOD ca nc thi sau kh qua b lng ct gim 5%
v cn li
- CSS2 = CSS1 (100 5)%
- CSS1 = 245 mg/l, hm lng cht l lng khi qua chn rc
CSS2 = 245 (100 5)% = 233 mg/l
- CCOD2 = CCOD1 (100 5)%
- CCOD1 =540 mg/l, hm lng COD ban u
CCOD2 = 540 (100 5)% =513 mg/l
- CBOD2 = CBOD1 (100 5)%
- CBOD1 = 259 mg/l, hm lng BOD khi qua chn rc
CBOD2 = 259 (100 5)% = 246 mg/l
2.2.3 B vt du m
Nc thi ca mt s x nghip n ung, ch bin b sa, cc l m, x nghip p
du... thng c ln du m. Cc cht ny thng nh hn nc v ni ln trn mt
nc. Nc thi sau x l khng c ln du m mi c php cho chy vo cc thy vc.
3/2
3/1
4,01
4,01.
3,0*3,1
116,0
P
-
BI 2: X L NC THI BNG PHNG PHP C HC 49
Hn na, nc thi c ln du m khi vo x l sinh hc s lm bt cc l hng vt liu
lc, phin lc sinh hc v cn lm hng cu trc bn hot tnh trong aerotank...
Ngoi cch lm cc gt n gin bng cc tm si qut trn mt nc, ngi ta ch
to ra cc thit b tch du, m t trc dy chuyn cng ngh x l nc thi.
Thng c p dng khi x l nc thi c cha du m (nc thi cng nghip). i
vi nc thi sinh hot, khi hm lng du m khng cao th vic vt du m c thc
hin ngay b lng nh thit b gt ni
Hnh 2.10. B vt du KCN Tn Bnh
TNH TON
- Chiu di cng tc: L = K.(v/umin).h.
Bng 2.4. K: h s ph thuc dng chy, ph thuc (v/umin).
v/umin 10 15 20
K 1.5 1.65 1.75
- Cng thc Stock xc nh umin:
-
50 BI 2: X L NC THI BNG PHNG PHP C HC
-
2.18
1hnhm dgu
d: ng knh du.
n, d: t trng ring ca du v nc. (g/cm3).
: nht nc thi ( 200c: =0,01).
- Din tch tit din ngang: f = Q/v.sao
- Chiu su cng tc: h = f/B. (B: b rng b)
- Dung tch: W = B. L .h.
- Thi gian lng: t = L/v.
V d p dng: Hy tnh ton b vt du m cho h thng x l nc thi c cng
sut 200 m3/ngy,
Chn thi gian lu nc l 2h
Ti trng b mt 40 (m3/m2.ng.)
Chn kiu thit k di : rng l 1 : 4
Th tch ca b lng:
V = Q*T = 200*2 = 400 (m3/m2.ng.) = 16.67 (m3/h)
Din tch b mt:
Chiu rng b mt:
Ly B = 1.2 m
Chiu di L = 4*B = 4.8 m
Din tch F = 5.76 m2
Ti trng b mt
(nm trong gii hn cho php bng 4-3 sch tnh ton thit k cc cng trnh XLNT)
Chiu cao b:
m
h35.1
2540
200m
U
QF
o
mB
mBBBLBF
12.1
5*4*4** 22
72.3476.5
200
F
QU o
98.276.5
67.16
F
Vh
-
BI 2: X L NC THI BNG PHNG PHP C HC 51 Chn h = 2.9m
Th tch b lng:
V = F*h = 5.76*2.9 = 16.7 m3
Thi gian lu nc trong b
Vn tc nc chy trong vng lng:
Hiu qu kh BOD
Hm lng BOD cn li sau khi qua b lng 1
Hm lng COD cn li sau khi qua b lng 1:
BOD = BODv*(100 34.48)% = 672*(100-34.48)% = 440.3 (mg/l)
2.2.4 Tuyn ni:
2.2.4.1 Mc ch
- Tch cc tp cht ( dng ht rn hoc lng) phn tn khng tan, t lng km ra khi
pha lng.
hQ
VT 2
24
200
7.16
smhB
Qv /0007.0
9.2*2.1*86400
200
*
%48.342*02.0018.0
2
bta
tRBOD
lmgBODBOD dv /5.314%48.34100480%48.34100*
Hnh 2.11. M hnh b tuyn ni DAF
-
52 BI 2: X L NC THI BNG PHNG PHP C HC
- Tch cc cht ha tan nh cht hot ng b mt.
- Trong x l nc thi:
Tch cc cht l lng.
Lm c bn sinh hc.
- ng dng:
X l nc thi sinh hot.
X l nc thi cng nghip:
Nhim du.
Thuc da.
Ch bin tht
Ti ch giy
2.2.4.2 V tr b tr
- L giai on x l s b trc khi x l sinh hc v ha hc.
C th thay th b lng.
C th ng trc hoc sau b lng.
- L giai on x l trit sau khi x l sinh hc.
V d:Nc thi t nh my Song chn rc B iu ho (my thi kh) Thit
b tuyn ni Thit b lc sinh hc BIOFOR- hiu kh (my thi kh) Thit b lng
ng ( B cha bn Xe ch bn) Thit b lc p lc B kh trng vch
ngn (H/C kh trng) Nc thi sau x l thi ra ngun tip nhn t tiu chun.
2.2.4.3 Nguyn tc x l
- To s tip xc gia pha kh v pha rn trong pha lng.
- Pha kh s kt dnh vi pha rn.
- Lc ni ln s y tp hp kh rn ln trn.
Sau s tp hp li thnh cc lp bt cha cc hm lng rn cao hn so vi ban
u. vt ra
2.2.4.4 Cc phng php tuyn ni
a. Tuyn ni phn tn khng kh bng thit b c hc
-
BI 2: X L NC THI BNG PHNG PHP C HC 53
b. Tuyn ni vi tch khng kh t nc.
Bn cht:
- To dung dch qu bo ha khng kh.
- Khi gim p sut cc bt kh s tch ra dung dch v lm ni cht bn ln.
Phn loi:
- Theo cch gim p sut:
Tuyn ni chn khng,
Tuyn ni p sut
- Theo ch hon lu nc:
Tuyn ni tun hon.
Tuyn ni khng tun hon.
-
54 BI 2: X L NC THI BNG PHNG PHP C HC
Tuyn ni chn khng :
Nguyn tc hot ng:
- Nc thi c bo ha khng kh p sut kh quyn trong bung sc kh.
- Vo bung tuyn ni, p sut khong 225 300 mmHg nh bm chn khng.
- Khi cc bt kh rt nh ni ln v ko theo cht bn.
- Thi gian l 20 pht.
u im:
- S hnh thnh rn kh din ra trong mi trng tnh (xc xut v thp).
- Chi ph nng lng thp.
Khuyt im:
- S lng bt kh nh nn khng p dng cho nc thi c SS ln (
-
BI 2: X L NC THI BNG PHNG PHP C HC 55
-
56 BI 2: X L NC THI BNG PHNG PHP C HC
Hnh 2.16. Cm cng trnh truyn ni ang thi cng
a. Tuyn ni in, sinh hc, ha hc.
-
BI 2: X L NC THI BNG PHNG PHP C HC 57 Tuyn ni in
- ng knh bng kh vo khong 20 100 m.
- Cn phi chn ph hp:
Loi vt liu.
ng knh si anot v catot.
Mt dng in. ( ti u: 200 260 A/m2 )
Tuyn ni sinh hc
- Dng c c t b lng t 1.
- Cn c a vo 1 b v un nng t 35 55o trong vi ngy.
- VSV pht trin ln men sinh ra cc cht kh (CO2, CH4) ko cn ni ln trn.
- Gt b cn.
- Kt qu cn c gim m n 80%.
Tuyn ni ha hc
- Qu trnh ha hc sinh ra cc bt kh nh O2, Cl2, CO2
- Bt kh ny kt dnh cc cht l lng.
- Nhc im: tiu hao ha cht.
Ngoi ra cn c cc phng php tuyn ni khc nh:
- Tuyn ni ion.
-
58 BI 2: X L NC THI BNG PHNG PHP C HC
- Tuyn ni tch phn on bt.
- Tuyn ni tch phn on bt ri phn hy bc x.
V d: Thit k b tuyn ni vi cc thong s u vo nh sau:
CC THNG S U VO:
o = 37,5 (m3/h)
o BOD5 = 966,5 (mg/l)
o COD = 1842 (mg/l)
o SS = 210,8 (mg/l)
- CC THNG S THIT K:
o T s kh/cht rn: A/S = 0,03 mg kh/mg cht rn.
o Nhit nc thi l 30 oC
o ho tan khng kh: sa = 16,4 (mg/l)
o T s bo ho: f = 0,5
o Hiu sut x l SS t 85%
o COD gim 60%, BOD gim 50%
Tnh ton h thng tuyn ni:
Chn qu trnh tuyn ni kh ho tan khng tun hon. H thng gm 2 thit b:
- Bn to p:
Bn hnh tr lm bng thp chu lc. Chc nng chnh ca bn p lc l pha trn
khng kh vo trong nc thi, duy tr p sut theo yu cu thit k.
- B tuyn ni:
B hnh tr gm 3 vng: vng trung tm pha trn thc hin qu trnh tuyn ni, pha
di thc hin qu trnh lng cn. Vng bn ngoi thu nc sch c cch ly vi vng
tuyn ni bng vch ngn kim loi.
- Bn trn ho cht:
Bn 100 l dng pha dung dch NaOH 30%, dung dch c khuy trn bng th
cng v c bm nh lng chm vo trc b UASB trung ho nc thi. Lng
NaOH s dng ph thuc vo pH nc thi khi vn hnh.
- TNH TON
Tnh ton bn to p:
- p lc yu cu cho ct p lc c tnh theo cng thc sau:
h
tbQ
-
BI 2: X L NC THI BNG PHNG PHP C HC 59 (Theo Lm Minh Trit XLNT th v cng nghip / trang 451)
= 263,51 KPa = 26,9 m ct nc
- Th tch bn to p:
Trong :
t: thi gian lu nc trong bn to p (pht), t = 0,53 pht, chn t = 2 pht.
- Chn chiu cao bn to p h = 2 m
- ng knh bn to p:
Chn d = 1 m.
Tnh b tuyn ni
- ng knh vng tuyn ni:
Ly Dtn =4(m)
Trong :
Dtn: ng knh vng tuyn ni i vi b c vng lng (m)
: lu lng trung bnh (m3/h)
Uo: vn tc nc trong vng lng, Uo = 4,7 (m/h)
a
a
S
pfs
S
A 13,1
a
a
s
S
S
Apf
3,11
fs
S
S
A
p a
a
3,1
1
atm6,25,0
4,163,1
8,21003,01
325,160
125,37 m
phut
htQW htb
mh
Wd 9,0
14,32
25,144
mDU
QD k
o
h
tbtn 817,31,2
7,414,3
5,3744 22
h
tbQ
-
60 BI 2: X L NC THI BNG PHNG PHP C HC
Dk: ng knh vng tuyn ni i vi b tuyn ni khng c vng
lng (m)
Uk: vn tc nc trong vng tuyn ni, Uk = 10,8 (m/h).
- Chiu cao vng tuyn ni:
Trong :
t: thi gian tuyn ni (pht), t =15 40 pht, chn t = 20 pht.
- Chiu cao vng lng : hl =0,5 (m)
- ng knh b:
ng knh b ly bng 125% ng knh vng tuyn ni
- B rng vng thu nc:
- Tnh chiu di ngn thu cht ni
Chiu di ngn thu cht ni ly bng bn knh b:
- B rng ngn thu Bmang = 400 mm,
- Tit din t ca mng:
- Ti trng mng thu:
- Tnh lng bn thu c t tuyn ni:
Hiu qu x l cht rn l lng ca h thng tuyn ni l : E= 85%.
- Hm lng SS sau x l tuyn ni:
mU
QD
k
h
tb
k 1,28,1014,3
5,3744
mphut
htUH ktn 6,3
60
1208,10
mDD tnbe 5%1252%125
mDD
B tnbe 5,02
45
2
mD
l be 5,22
5
2
214,05,2 mBlF mangmang
hmmF
Qa
mang
h
tb
m ./5,371
5,37 23
lmgSSSS vaosau /44,49%85%1006,329%85%100
-
BI 2: X L NC THI BNG PHNG PHP C HC 61 - Lng SS thu c 1 ngy:
Gi s bn ti ny c hm lng cht rn TS = 3,4%. T l VSS:SS = 65%. Khi
lng ring Sv = 1,0072 (kg/l).
- Dung tch bn ti cn x l mi ngy
- Khi lng VSS cn x l mi ngy:
=4,5 HP
Trong :
G: trng lng ca dng khng kh = 0,025(kg/s)
R: Hng s kh R=8,314 (KJ/K.mol.oK)
T: Nhit tuyt i ca khng kh u vo (oK)
P1: p sut tuyt i ca khng kh u vo (atm)
P2:p sut tuyt i ca khng kh u ra (atm)
: v i vi khng kh K=1,395
29,7: H s chuyn i
e : Hiu sut my nn kh
Sau tuyn ni BOD5 gim 50%, COD gim 60%:
Nng BOD5 sau x l:
- Nng COD sau x l
- Hm lng SS sau x l tuyn ni:
Tnh lng NaOH 30% dng trung ho nc thi:
ngaykgSSg
kgQESSM ngtbvaossv /84
1000
1300%856,329
ngaykgVSSMM SSvVSSv /6,5465,08465,0)()(
)(37,311
6,2
7,0283,07,29
308314,8025,01
7,29
283,0283,0
1
2 kWP
P
en
TRGN
283,01
K
Kn
lmgBODBOD vaosau /3,498%)50%100(5,966%)50%100(55
lmgCODCOD vaosau /8,736%60%1001842%60%100
lmgSSSS vaosau /44,49%85%1006,329%85%100
303
-
62 BI 2: X L NC THI BNG PHNG PHP C HC
Nc thi c : pH = 6
Yu cu u vo b UASB: pH = 7
- Nng [OH-] cn dng l:
- Lng NaOH 30% rn cn dng cho 1m3 nc thi:
- Lng NaOH 30% rn dng trong 1 ngy:
2.2.5 X l bng phng php lng
2.2.5.1 C s l thuyt lng
Lng l qu trnh tch khi nc cn l lng hoc bng cn hnh thnh trong giai on
keo t to bng hoc cc cn bn sau qu trnh x l sinh hc
Trong cng ngh x l nc thi qu trnh lng c ng dng :
- Lng ct, sn, mnh kim loi, thu tinh, xng, ht st,.. b lng ct.
- Loi b cht l lng b lng t 1.
- Lng bn hot tnh hoc mng vi sinh vt b lng t 2.
Hai i lng quan trng trong vic thit k b lng chnh l tc lng v tc
chy trn. thit k mt b lng l tng, u tin ngi ta xc nh tc lng ca
ht cn c loi v khi t tc chy trn nh hn tc lng.
Tnh cht lng ca cc ht c th chia thng 3 dng nh sau :
Lng dng I: lng cc ht ri rc. Qu trnh lng c t trng bi cc ht lng mt
cch ri rc v tc lng khng i. Cc ht lng mt cch ring l khng c kh nng
keo t, khng dnh bm vo nhau sut qu trnh lng. c th xc nh tc lng
dng ny c th ng dng nh lut c in ca Newton v Stoke trn ht cn. Tc
lng dng ny hon ton c th tnh ton c.
Lng dng II: lng bng cn. Qu trnh lng c t trng bi cc ht ( bng cn)
kt dnh vi nhau trong sut qu trnh lng. Do qu trnh bng cn xy ra trn cc bng
cn tng dn kch thc v tc lng tng. Khng c mt cng thc ton hc thch hp
no biu th gi tr ny. V vy c cc thng s thit k v b lng dng ny, ngi
lmolH /10 6
lmolH /10 7
lmolOH /1091010 776
337 /2,130
100)/(40)/(1000109 mgmolglmm
ngaygmng /363002,1
-
BI 2: X L NC THI BNG PHNG PHP C HC 63
ta th nghim xc nh tc chy trn v thi gian lng hiu qu kh bng cn cho
trc t ct lng th nghim, t nhn vi h s quy m ta c tc chy trn v thi
gian lng thit k.
Lng dng III: lng cn tr. Qu trnh lng c t trng bi cc ht cn c nng
cao (> 1000mg/l). Cc ht cn c khuynh hng duy tr v tr khng i vi cc v tr
khc, khi c khi ht nh l mt th thng nht lng xung vi vn tc khng i.
Lng dng ny thng thy b nn bn.
CC BC TIN HNH.
- Chun b thng cha nc thi v khuy trn u nc thi.
- Chun b ct lng hnh hp
- Bm nc th vo ct lng : V
- lng 1 pht. Ly mu nc kim tra c (SS) cc su khc nhau ng vi
thi im khc nhau (5, 10, 15, 20, 40, 60, 90 pht, cho n khi SS = 0) cc
su khc nhau: 1.8, 1.4, 1.0, 0.6, 0.4 m
- Sau khi o c ta tnh ton hiu qu lng theo cng thc sau:
-
64 BI 2: X L NC THI BNG PHNG PHP C HC R% =( 1 - C1 / C0 ) x 100%.
R% :hiu qu mt chiu su tng ng vi mt thi gian lng%.
C1 :hm lng SS thi gian t su h, mg/L.
C0 :hm lng SS ban u, mg/L.
Lp bng kt qu o SS
Cao
(m)
Co
(mg/l)
5 (pht) 10 15 20 40 60 90
0.2
0.6
1.0
1.4
1.8
Lp bng hiu qu sau khi lng tnh ra % (R)
Cao
(m) 5 (pht) 10 15 20 40 60 90
0.2
0.6
1.0
1.4
1.8
KT QU TH NGHIM
Dng th vi trc honh biu th thi gian ly mu, trc tung biu th chiu su. V
biu hiu qu lng.
Ni suy cc ng cong hiu qu lng bng cch ni cc im c cng hiu qu lng
nh m hnh gi sau:
-
BI 2: X L NC THI BNG PHNG PHP C HC 65
T giao im gia ng cong hiu qu lng v trc honh, xc nh tc chy
trnV0 = H / ti . Trong H l chiu su ct (2m), ti l thi gian ly mu c xc nh t
giao im ng