Vấn đề rác thải, nước thải ra sông Hồng và khả năng ảnh ...tapchi.vnu.edu.vn/tn_2_07/b5.pdf · Vấn đề rác thải, nước thải ra sông Hồng và

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  • Tp ch Khoa hc i hc Quc gia H Ni, Khoa hc T nhin v Cng ngh 23 (2007) 107-117

    107

    Vn rc thi, nc thi ra sng Hng v kh nng nh hng n nc di t khu vc H Ni

    Nguyn Vn Hong1,, Trn Vn Hng2 1 Vin a cht, Vin Khoa hc v Cng ngh Vit Nam, 84 Cha Lng, Lng Thng, H Ni, Vit Nam

    2 Vin Ha hc, Vin Khoa hc v Cng ngh Vit Nam, 18 Hong Quc Vit, H Ni, Vit Nam

    Nhn ngy 23 thng 4 nm 2007

    Tm tt. Ngy cng c nhiu ngun rc thi v nc thi thi ra sng Hng gy mt cnh quan, lm nhim trc tip nc sng Hng v nhim gin tip ti nc di t (ND). Bi bo trnh by kt qu iu tra kho st v v tr cc ngun thi ra sng Hng khu vc H Ni v cht lng nc thi. Kh nng lm nhim ND do nc thi ra sng Hng c nh gi bng m hnh phn t hu hn lan truyn cc cht nhim trong ND thc hin i vi bi ging Co nh 2. Kt qu m hnh cho thy iu kin cht nhim khng b mi trng t hp th-trao i dng chy ND c nng cht nhim tng i bng 0.8 xm nhp vo cc l khoan khai thc ca bi ging Co nh 2 sau mt nm k t thi im thm vo tng Pleistocen t nc sng Hng.

    1. Ch dng chy ca sng Hng v cc ngun nhim ven sng Hng khu vc H Ni

    Dng chy sng Hng c chia lm hai ma r rt, ma l ng vi ma ma nhiu trong nm v ma cn ng vi ma ma t. Vo ma cn t ma, dng chy sng ngi trn ton b h thng sng Hng ch yu do nc ngm cung cp. Theo s liu sau khi c p thy in Ho Bnh (19891995), lu lng ln nht quan trc c ti trm H Ni l 13500m3/s, lu lng nh nht l 448m3/s [1]. Chnh lch lu lng gia ma l v ma kit xp x 20 ln.

    C nhiu ngun thi vo sng Hng khng ch ring khu vc H Ni m c thng ngun v h lu so vi H Ni.

    ______ Tc gi lin h. T: 84-4-8343068-416

    E-mail: [email protected]

    Ngun thi cng nghip: pha thng ngun in hnh l tnh Ph Th c hng chc nghn c s cng nghip m nc thi khng c qua x l vo sng Hng. in hnh l nh my giy Bi Bng (lu lng nc thi l 3800m3/ngy), Supe pht pht Lm Thao (lu lng nc thi l 4500m3/ngy), dt Vnh Ph (lu lng nc thi l 1500m3/ngy), nh my ha cht Vit Tr, nh my giy Vit Tr (lu lng nc thi l 4390m3/ngy), cc x nghip ch bin lm sn, ru-bia... Cc s liu phn tch cht lng nc cho thy nc thi ti ca x ca nh my giy Vit Tr c BOD5 t 68.5mg/l, ti ng ba Vit Tr, ti di ca x nc ca nh my giy Bi Bng v nh my Supe Lm Thao BOD5 t 15.3-20.5mg/l [2].

    Ngun thi nng nghip: cc hot ng sn xut nng nghip s dng thuc tr su v phn bn hai bn sng Hng tnh t cu Thng Long ln pha thng lu lun to ra

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 108

    mt lng nc chy b mt c cha mt hm lng nht nh cc cht ny hoc trc tip hoc gin tip thot vo sng Hng. Nhiu on sng c nhng bi bi c canh tc vo thi k nc thp v ng nhin nhng d tha thuc tr su phn bn ha hc s l ngun nhim trc tip vo nc sng Hng. Ngoi ra phn gia sc th rng v t chung tri chn nui cng l mt ngun nhim hu c v vi sinh n nc sng Hng.

    Ngun thi sinh hot: hai bn sng Hng l h thng chng lt, nhng nhiu khu

    vc dn c ng c sng pha trong v ngay trn . Rc thi sinh hot nhiu ni c trc tip b sng. Nc thi sinh hot cng theo cc cng rnh ra sng Hng. Vic ny r rng gy nhim nc sng Hng ni ring, ti nguyn nc ni chung v cnh quan mi trng.

    tin hnh iu tra kho st hin trng rc thi v nc thi ven sng Hng khu vc thnh ph H Ni. V tr th hin trong Bng 1 v Hnh 1.

    Bng 1. Cc v tr thi nc thi ra sng Hng v rc thi ven sng Hng

    K hiu a ch K hiu a ch

    NT4 Cng thi =1m: thn Trung Quan-Vn c-Gia Lm

    NT13 Lin Mc-ng Ngc-T Lim

    NT3 Cng thi =1m: thn Thng Nht-Kim Lan-Gia Lm

    NT14 Yn H-Hi Bi-ng Anh

    NT5 Cng nc thi nh: ng 695 Bch ng RT5 Bi rc thi nh 2m3: ng 695 Bch ng

    NT6 Cng nc thi nh: t 20-Thanh Tr-Hong Mai

    RT1 Bi rc thi nh 2-3m3: pha Nam chn u cu Chng Dng b tri

    NT2 Cng thi =0,8m: Xm 2-Giang Cao-Bc Trng

    RT2 Bi rc thi nh 2-3m3: pha Bc chn u cu Chng Dng b tri

    NT1 Cng thi nc sinh hot: pha Nam chn u cu Long Bin b tri

    RT7 Rc thi cng ty du lch Sng Hng: ng 193 Bch ng

    NT7 Cng nc thi nh cng ty du lch Sng Hng: ng 193 Bch ng

    RT9 Rc thi: ng 133-Tn p

    NT8 Cng nc thi: ph Bo Linh-t 4-Phc Tn-Ty H

    RT9B Xm Tri phng T Lin

    NT9 Cng nc thi: ng 133-Tn p RT12B Xm 5B, Lin Ngc-ng Ngc-T Lim

    NT10 Cng nc thi: Ng 2-cm 8, t 49, ng An Dng Vng, phng Ph Thng, Ty H

    RT12C Xm 5A, Lin Ngc-ng Ngc-T Lim

    NT11 Ph X-ng An Dng Vng-Ph Thng-Ty H

    RT15 T 1, thn i -Vng La-ng Anh.

    NT12 Lin Mc-ng Ngc-T Lim

    Ghi ch: NT: nc thi; RT: rc thi.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 109

    Hnh 1. Cc v tr nc thi ra sng Hng v rc thi ven sng Hng.

    im NT11. Nc thi ra sng Hng ti ng An Dng Vng-Ph Thng-Ty H.

    im RT12C. Rc thi ti xm 5A, Lin Ngc-ng Ngc-T Lim.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 110

    Cc ngun nc thi iu tra trn khu vc ch yu l nc thi sinh hot nn khng phn tch cc cht c hi cng nghip nh kim loi nng m ch phn tch nhu cu xy ho hc (mt ch tiu gin tip th hin giu cc hp cht hu c trong nc) v NO3 (mt thng s th hin mc nc nhim nit). Kt qu th hin trong Bng 2.

    Bng 2. Hm lng NO3 v nhu cu xy ha hc (COD ) cc mu nc thi

    STT

    Nng

    NO3 (mg/l)

    COD (mg/l)

    STT

    Nng

    NO3 (mg/l)

    COD (mg/l)

    NT1 26 320 NT9 21 300 NT2 22 545 NT8 23 310 NT3 17 290 NT9 21 300 NT4 28.5 1340 NT10 16 280 NT5 14 90 NT11 25 250 NT6 23 350 NT12 22 300 NT7 21 230 NT13 17 220 NT8 23 310 NT14 21 320

    Trung bnh: 21 368

    Din tch ngoi pha Bc sng Hng thuc a bn H Ni l khong 80km2, pha Nam l 64km2, tng din tch hai khu vc ny l khong 144 km2 (din tch ton thnh ph H Ni l 913 km2). Nu ly dn s t l vi din tch v dn s H Ni nm 2005 l 5 triu dn th s dn sng khu vc ny l khong 790000 ngi. Vi lng nc s dng l 0.08m3 v 75% nc sinh hat tr thnh nc thi th lng nc thi l 47400m3/ngy.

    ______ Trong bi bo s dng du chm ch phn thp phn.

    Lng nc thi ny bng 0.12% dng chy kit nht l 448m3/s.

    2. M hnh nh gi xm nhp cc cht nhim trong nc sng Hng vo cc cng trnh khai thc b sung ven sng

    Tnh ton d bo kh nng nhim nc khai thc b sung ven sng c tin hnh i vi khai thc nc m rng giai on 2 ca nh my nc Co nh-H Ni. Trong giai on hai d nh xy dng thm cc l khoan khai thc mi. S h thp mc nc ln nht, v do kh nng xm nhp cc cht nhim ch yu xy ra trn khu vc ln cn cc l khoan khai thc ny, c th l t pha sng Hng. Vic xc nh phu h thp mc nc di t (dng xc nh vn tc dng chy) tin hnh tnh ton lan truyn cc cht nhim t sng Hng vo cc l khoan giai on 2 ca nh my nc Co nh v mt nguyn tc cn phi thc hin trn ton khu vc H Ni, hay t ra cng trn khu vc rng bao gm phm vi nh my nc Bc Chm, Thng Ct, Co nh, Yn Ph, Mai Dch, Ngc H. Nhng l mt cng vic phc tp tn km thi gian v tin ca, hn na mc nc h thp ln cn cc l khoan ny ch yu gy nn bi cc l khoan ca chnh nh my nc Co nh (Hnh 2).

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 111

    Hnh 2. V tr cc l khoan khai thc nc nh my nc Co nh v min m hnh lan truyn nhim.

    Vic xc nh mc nc (hoc i lng h thp mc nc) do bm ht t cc l khoan c th tnh bng phng php gii tch hoc phng php m hnh s. Trong khun kh ca nghin cu ny phng php gii tch c s dng. i lng h thp mc nc h ti bt k mt v tr no do khai thc nc lin tc t nhiu l khoan c xc nh theo cng thc Theis sau y [3]:

    ( )2

    1

    2 ; 4 4

    iN

    i

    i TB

    rQh W u u

    Km at

    =

    = + =

    (1)

    Trong : h-i lng h thp mc nc so vi mc nc ban u (m); N-s lng l khoan khai thc; Qi-lu lng khai thc ca l khoan th i (m3/ng); a=KmTB-h s dn mc nc (dn p) (m2/ng); K- h s thm ca tng cha nc (m/ng); mTB-chiu dy trung bnh ca tng cha nc trong qu trnh khai thc (m); ri-khong cch (m) t im xc nh i lng mc nc n l khoan khai thc i; t-thi gian tnh t lc bt

    u khai thc n thi im tnh ton (ng); W-hm s Theis; -h s sc cn ca l khoan do tnh khng hon thin.

    Do c sc cn lng sng v cc lp t gia y sng v tng cha nc Pleistocen nn bin p lc nc khng i ca sng Hng phi c dch v pha xa cc l khoan bm ht mt i lng L m theo cc bo co chuyn ngnh trc y c gi tr l 220m [4]. V thng s a cht thy vn ca tng c th ly trung bnh cho ton khu vc theo bo co thm d t m nm 1993 v bo co kt qu thm d khai thc bi ging Co nh giai on I nm 1996 l: h s dn nc T=1500m2/ng, h s dn p a=2.3106h s nh nc n hi S*=0.000652 [5]. Lu lng khai thc ca tng l khoan l 4320m3/ng (tng lu lng ca 10 l khoan l 43200m3/ng). Kt qu tnh ton cho thy mc nc t hu nh n nh sau 5 nm (Hnh 3).

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 112

    18580 18581 18582 18583 18584 18585 18586 18587

    Kinh tuyn (km) (h ta Quc gia VN 2000)

    2330

    2331

    2332

    2333

    2334V

    tu

    yn

    (km

    ) (h

    t

    a

    Q

    u

    c g

    ia V

    N 2

    00

    0) H thp mc nc sau 5 nm

    H thp mc nc sau 10 nm

    (Du tr th hin mcnc ban u l 0m)

    Hnh 3. S cc ng ng h thp mc nc (du - ch h thp) (m).

    3. Kt qu M hnh xm nhp cc cht nhim vo bi ging Co nh 2

    minh ho kh nng xm nhp cc cht nhim trong nc thi ra sng Hng v nc rc r r ra sng Hng ta tin hnh m hnh qu trnh lan truyn cc cht nhim khng tnh n qu trnh trao i hp th cng nh khng xt n s pha long nc b nhim trong lng nc c khai thc. Lan truyn cc cht nhim trong nc di t bi c hai c ch dch chuyn v phn tn thy ng lc c thc hin bng phng php phn t hu hn. Min m hnh c chiu rng l 555m (theo hng vung gc vi tuyn phn b cc l khoan khai thc ca nh my Co nh giai on 2) v chiu di

    l 1500m (theo hng song song vi tuyn phn b cc l khoan khai thc ny) (Hnh 2). Li phn t hu hn gm 3838 nt v 3700 phn t c kch thc l 15m 15m. Vn tc dng chy tnh qua mc nc (trn Hnh 4), h s thm ca t tng cha nc l 25m/ngy, l rng hu hiu l 0.1. Cc nt trn sng Hng l nt mn bin c nng cht nhim bit (Hnh 4), cc bin cn li c dng chy cht nhim vo bng 0. Bc thi gian c chn l 1 ngy v chy m hnh cho thi gian 730 ngy tnh t khi bt u khai thc. Do mc nc h thp n nh ch sau 5 nm tnh t khi khai thc nn cc kt qu tnh ton lan truyn cng c th s dng nh gi xm nhp cc cht nhim t thi im bt u c thi ra sng Hng.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 113

    0 100 200 300 400 500

    Khong cch (m) (hng vung gc vi b sng)

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    1000

    1100

    1200

    1300

    1400

    1500

    Kh

    on

    g c

    ch (

    m)

    (h

    ng

    song

    son

    g v

    i

    ng

    ph

    n b

    c

    c L

    K k

    hai

    th

    c)

    ng

    ra

    nh

    gi

    i v

    i s

    ng H

    n

    g (

    bi

    n c

    n

    ng

    cht

    n

    hi

    m

    x

    c

    nh)

    Hnh 4. Li phn t hu hn m hnh lan truyn cht nhim.

    Kt qu m hnh lan truyn cht nhim th hin trn cc hnh 5-8 v cho thy ch sau vi thng cht nhim xm nhp vo cc

    l khoan khai thc, nhanh nht l cc l khoan pha nm pha Ty Bc ca tuyn.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 114

    0 100 200 300 400 500

    Khong cch (m) (hng vung gc vi b sng)

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    1000

    1100

    1200

    1300

    1400

    1500

    Kh

    on

    g c

    ch (

    m)

    (h

    ng

    son

    g so

    ng

    vi

    n

    g p

    hn

    b c

    c L

    K k

    hai t

    hc)

    sng Hng

    Khu

    v

    c ph

    n

    bc

    c LK

    kha

    i th

    c

    Hnh 5. Phn b nng tng i cht nhim sau 2 thng.

    0 100 200 300 400 500

    Khong cch (m) (hng vung gc vi b sng)

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    1000

    1100

    1200

    1300

    1400

    1500

    Kh

    on

    g c

    ch (

    m)

    (h

    ng

    son

    g so

    ng

    vi

    n

    g p

    hn

    b c

    c L

    K k

    hai t

    hc)

    sng Hng

    Khu vc phn bcc LK khai thc

    Min t ng nng tng i bng 0.95ra sng c nng tng i ln hn 0.95

    Hnh 6. Phn b nng tng i cht nhim sau 8 thng.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 115

    minh ha cho vic xc nh nng tuyt i qua phn b nng tng i la ly th d vi cht nhim l NO3 c nng trung bnh trong nc thi l 21mg/l v nu c pha long cng nc sng Hng c nng l 10.5mg/l. Cng b qua qu trnh hp th cng nh qu trnh bin i NO3. Phn b nng NO3 trong nc di t trn min m hnh th hin trn Hnh 7

    (sau 2 thng) v Hnh 8 (sau 6 thng). Cc ng phn b nng ny chnh l cc ng phn b nng trn hnh 5 v 6 nhng c gi tr nng tuyt i bng gi tr tng i nhn vi 10.5 (th d ng nng tng i 0.5 s tng ng vi ng nng NO3 tuyt i l 0.5 10.5mg/l=5.25mg/l.)

    0 100 200 300 400 500

    Khong cch (m) (hng vung gc vi b sng)

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    1000

    1100

    1200

    1300

    1400

    1500

    Kh

    o

    ng c

    ch

    (m

    ) (h

    ng s

    on

    g s

    on

    g v

    i

    n

    g ph

    n

    b

    cc

    LK

    kha

    i th

    c)

    sng Hng

    Kh

    u v

    c

    ph

    n b

    c

    c L

    K k

    hai

    th

    c

    Hnh 7. Phn b nng NO3 sau 2 thng.

    0 100 200 300 400 500

    Khong cch (m) (hng vung gc vi b sng)

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    1000

    1100

    1200

    1300

    1400

    1500

    Kh

    o

    ng c

    ch

    (m

    ) (h

    ng s

    on

    g s

    on

    g v

    i

    n

    g ph

    n

    b

    cc

    LK

    kha

    i th

    c)

    sng Hng

    Khu vc phn bcc LK khai thc

    Min t ngnng bng10mg/l ra sngc nng ln hn 10mg/l

    Hnh 8. Phn b nng NO3 sau 6 thng.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 116

    4. Kt lun

    Sng Hng khng ch n thun c vai tr trong giao thng ng thy, mi trng cnh quan sinh thi, thy li, s dng trong sinh hot ca ngi dn hai bn sng, c th khai thc x l tp trung ln cp nc sinh hot, m cn l ngun nc cung cp cho cc cng trnh khai thc ND ven sng Hng. T l nc sng Hng trong lng nc khai thc t cc l khoan ven sng rt ln, c th t ti trn di 90%. Vic thi rc thi ra b sng v thot nc thi ra sng Hng khng ch gy mt cnh quan sinh thi v gy nhim nc sng Hng m cn gy nhim ND, c bit l nhim nc khai thc t cc l khoan khai thc gn sng (cng trnh b sung thm lc).

    Theo kt qu m hnh lan truyn cht nhim khng tnh n qu trnh trao i hp th cng nh khng xt n s pha long nc b nhim trong lng nc c khai thc nu trn th cht nhim xm nhp vo cc l khoan khai thc ND nm cch mp nc sng Hng vi trm mt ch sau vi thng. iu ny s rt bt li cho cc cng trnh khai thc b sung thm lc ven sng, m thm ch nm ngay trn cc bi bi ven sng trong tng lai. Vi mc tc th ha nh hin nay th dn c v cc c quan, cng s v x nghip s tng rt nhanh trn khu vc ven sng Hng v p lc v rc thi v nc thi ra sng s gia tng. V vy rc thi v nc thi hai bn sng Hng ni chung v khu vc H Ni ni ring cn c

    thu gom x l trit khng cho thi trc tip ra sng Hng. Trc mt cn tin hnh thu dn cc bi rc thi v khng cho tip tc thi nc thi ra sng Hng cc khu vc gn cc bi ging khai thc ven sng Hng. Cn b tr cc l khoan quan trc cht nc ND khu vc gia cc bi ging khai thc ND v cc bi rc thi v ni thot nc thi ven sng Hng.

    Ghi nhn: Bi bo c thc hin trong khun kh ti nghin cu c bn nm 2006-2008 mang m s 71 05 06.

    Ti liu tham kho

    [1] Nguyn Vn C v nnk., Bo co tng kt ti cp thnh ph Hu qu sau sng i vi ng lc bin i lng dn v khai thc tng hp lng sng Hng on thuc a phn H Ni, H Ni, 1997.

    [2] Nguyn Quang Trung, Din bin cht lng nc trn mt s on sng chnh thuc h thng sng Hng v sng Thi Bnh, Tuyn tp kt qu khoa hc v cng ngh 1994-1999, Tp II, NXB Nng nghip, H Ni, 1999.

    [3] N.I. Drobnokhod, L.X. Lazvin, B.V. Borevskii, nh gi ngun nc di t, Nh xut bn Nera (Ting Nga), 1982.

    [4] Tng Cc a cht, Bo co thm d t m nc di t vng H Ni, on 64, Lin on 2, Tng cc a cht, 1984 (nay l Cc a cht khong sn-B Ti nguyn v Mi trng).

    [5] Cng ty CDC, D n nng cng sut Co nh ln 60000m3/ngy, Cng ty CDC-B Xy dng, 2002.

  • N.V. Hong, T.V. Hng / Tp ch Khoa hc HQGHN, Khoa hc T Nhin v Cng ngh 23 (2007) 107-117 117

    Solid waste and wastewater along the Red River issue and their effect on surface water and groundwater in Hanoi area

    Nguyen Van Hoang1, Tran Van Hung2 1 Institute of Geological Sciences, Vietnamese Academy of Science and Technology, 84 Chua Lang,

    Lang Thuong, Hanoi, Vietnam 2 Institute of Chemistry, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam

    There are more and more solid wastes and waste water discharging into the Red River, that causes ecological landscape, the direct Red River water pollution and indirect groundwater pollution. This paper presents the results of survey of solid wastes and wastewater along the Red River in Hanoi. The potential of groundwater pollution due to wastewater discharge into the Red River has been evaluated by groundwater solute transport finite element modeling for groundwater pumping field Co nh 2. The modeling results have shown that under conservative condition the groundwater with relative contaminant concentration of 0.8 may reach the pumping wells only after one year since the time the contaminant from the Red River has reached the Pleistocene aquifer.