Thiet Ke Dinh Hinh Cac Mau Nha Ve Sinh Nong Thon

B GIO DC V O TO

TRNG I HC CN TH KHOA CNG NGH

--- oOo ---

L ANH TUN

THIT K NH HNH CC MU

NH V SINH NNG THN

TI NGHIN CU KHOA HC CP TRNG

- 2005 -

Thit k nh hnh cc mu nh v sinh nng thn ThS. L Anh Tun -------------------------------------------------------------------------------------------------------------

LI M U --- oOo ---

Sc kho v v sinh mi trng c quan h cht ch vi nhau v l mt trong cc tiu ch ca cht lng sng. Trn 75% dn s Vit Nam sng tp trung cc vng nng thn, vng ni, hi o, ... m nhng ni , theo mt s kho st cho thy, khng qu 35% s h gia nh c nh x hp v sinh. iu ny cng lin quan n t l cc bnh truyn nhim cao nng thn. C nhiu nguyn nhn l gii cho mc t l thp ny, tuy nhin, iu ny l mt trong cc khc bit gia nng thn v thnh th . Hu ht, chnh ph cc nc trn th gii u c chng trnh quc gia v cp nc v v sinh mi trng cho c dn nng thn vi nhiu phng cch tip cn khc nhau. Qu UNICEF tin hnh Chng trnh Cp nc v V sinh Mi trng ti nhiu tnh thnh ca Vit Nam t nm 1982 n nay. Nc ta cng c Chin lc Quc gia Cp nc sch v V sinh Nng thn n nm 2020 v c Th tng Chnh ph k duyt ngy 25/8/2002 theo Quyt nh s 104/2000/Q-TTg. Vi mc tiu gp phn vo vic qung b v truyn thng vi cc phng cch xy dng nh v sinh cho ngi dn nng thn, ti liu Thit k nh hnh cc mu Nh V sinh Nng thn ny c bin son nh mt ti liu k thut nhm gii thiu cc kiu nh v sinh cng nh cch x l cht thi ngi tng i n gin, hiu qu, va tm thc hin cho cc vng nng thn Vit Nam cho cc vng sinh thi khc nhau, iu kin kinh t, x hi, tp qun, ... Ti liu ny c th phn pht cho cc cn b Pht trin Nng thn, Cp thot nc, Mi trng, ... Cc thut ng s dng trong ti liu l cc t tng i quen thuc trong nc. trnh nhm ln, mt s thut ng c phn ch thch ting Anh i km. Ngi c c th c thm cc ti liu tham kho trnh by cui quyn ti liu . Ti liu c bin son theo cc kin thc v kinh nghim thu thp ca tc gi. Do khng c iu kin tip xc, trao i xin php, mt s c trch dch t tc gi ca cc ti liu tham kho, mong qu v min chp. Mc du c nhiu c gng nhng ti liu khng th trch khi cc khuyt im, tc gi mong nhn c cc ph bnh, gp ca cc bn. Trn trng, L ANH TUN

---------------------------------------------------------------------------------------------------------------------------- PHN M U - MC LC

ii


MC LC ==========

trang ... TRANG BA LI M U ii MC LC iii 1. NH V SINH NNG THN VIT NAM - HIN TRNG V VN 1 1.1 TNG QUAN 1 1.1.1 Vn 1 1.1.2 Cc nguyn nhn hn ch vic xy dng nh v sinh nng thn 1 1.2 BNH TT LIN QUAN N NGUN NC V THIU NH V SINH 3 1.3 THNH PHN PHN V NC TIU NGI 7 1.4 MC TIU NGHIN CU 8 1.4.1 Lc kho ti liu trong v ngoi nc 8 1.4.2 Cc ch trng v chnh sch Quc t v Chnh ph 10 1.4.3 Thuyt minh s cn thit ca ti 11 1.4.4 Mc tiu ca ti 11 1.4.5 Kh nng ng dng kt qu ca ti 11 2. KIN THC C S V NH V SINH NNG THN 12 2.1 MT S NGUYN TC C BN I VI NH V SINH 12 2.1.1 B tr nh v sinh 12 2.1.2 Phn loi nh v sinh 13 2.2 YU CU XY DNG MT NH V SINH 18 2.3 QUI M XY DNG NH V SINH 19 2.4 CU TRC C BN V TN GI CC B PHN MT NH V SINH 24 2.5 CAO TRNH C BN CA MT NH V SINH 39 2.6 XC NH THM CA T NN NH V SINH 40 3. NH V SINH NNG THN KHNG DNG NC 41 3.1 KHI QUT 41 3.1.1 nh ngha v u khuyt im 41 3.1.2 phn compost 41 3.2 CC KIU H X KH C CHUYN VN PHN 42 3.2.1 H x thng 42 3.2.2 H phn "Bn trong Mt" kiu Tu 44 3.2.3 H x phn 2 ngn kiu Vit Nam 45 3.2.4 H x t hoi do ch nh t xy 48 3.2.5 H x t hoi kiu Guatemalan 48 3.2.6 H x t hoi c ng dn 49 3.2.7 H x ly phn bng xe 51 3.2.8 Nh v sinh kiu trng quay 52 3.2.9 Nh v sinh dng mt tri 52 3.3 CC KIU NH X KH KHNG C CHUYN VN PHN 53 3.3.1 Nh x trn sng hay cu tm 53

---------------------------------------------------------------------------------------------------------------------------- PHN M U - MC LC

iii

Thit k nh hnh cc mu nh v sinh nng thn ThS. L Anh Tun ------------------------------------------------------------------------------------------------------------- 3.3.2 H x cn 55 3.3.3 H x o chm 56 3.3.4 H x o chm kiu ROEC 57 4. NH V SINH C DNG NC 59 4.1 KHI QUT 59 4.2 THNG X N GIN 60 4.3 NH TIU SINH THI VINASANRES 63 4.4 NH TIU NC 65 4.5 NH V SINH CHO KHU DN C VT L 67 4.6 NH V SINH T HOI 69 4.7 G LC 71 5. QUN L NH V SINH TRN C S CNG NG 72 5.1 VN 72 5.2 CC XEM XT KHI QUYHOCH, THIT K V XY DNG 72 5.3 MT S KIU NH V SINH TP TH 77 5.3.1 H v sinh kiu rnh trong trng hp khn cp 77 5.3.2 Mt s kiu nh v sinh 78 5.4 X L PHN V NC TIU NH V SINH CNG CNG 82 5.5 MT S BI TOAN LAO NG CHO NH V SINH CNG CNG 83 5.6 CHI PH V NH MC NH V SINH 85 5.7 CHN LA CCH PHN COMOST 86 5.8 CCH CHNG RUI 88 5.9 CC VN CN NGHIN CU THM 92 Ph lc T IN TOILET ANH - VIT 93 TI LIU THAM KHO 99 ==============================================================

---------------------------------------------------------------------------------------------------------------------------- PHN M U - MC LC

iv


c NH V SINH NNG THN VIT NAM HIN TRNG V VN

=============================================================== 1.1. TNG QUAN 1.1.1. Vn Con ngi v gia sc lun lun to ra cht thi t chnh mnh, ch yu l phn v nc tiu. Cc cht thi ngi v gia sc l ngun mang nhiu mm bnh ngoi vn gy mi hi kh chu v mt thm m. Hnh 1.1 cho thy cc ng i ca bnh tt do nhim t cht thi ngi.

TI

NHIM BNH CNG NG DN C

bvc

THC PHM NHIM KHUN

LY NC N UNG

6

CN TRNG TRNG

TAY NGI NHIM PHN

, BN RAU EW

X XUNG NGUN NC

3

CHT THI NGI V VT NUI

Hnh 1.1 : ng i ca s ly nhim bnh tt t cht thi con ngi v gia sc

Cht thi t ngi v gia sc khi thi ra t nhin, khng c x l s i qua cc ng dn t ngun nc, t, cn trng v chnh tay chn ngi s xm nhp vo thc phm mang theo mm bnh tr li cho chnh con ngi v cng ng ca h. V vy, cc cht thi ny cn phi c cng trnh tip nhn v x l ti ch trc khi cho vo h thng chung. Cc h x gia nh hay tp th tr thnh mt nhu cu khng th thiu trong mt x hi hin i v vn minh.

----Ch- HI

----------------------------------------------------------------------------------------------------- ng 1: NH V SINH NNG THN VIT NAM N TRANG V VN

1


Cui nm 1990, nm cui ca thp k "Cung cp nc sch v v sinh mi trng ton cu", T chc Y t Th gii WHO c tnh trn ton th gii chi c 72% khu vc th c nh v sinh v con s ny l 49% i vi vng nng thn. Theo s liu thng k nm 2003, trn 75% dn s Vit Nam sng tp trung cc vng nng thn, min ni v hi o. Nhiu kho st gn y cho thy, s gia nh c nh v sinh (h x) hp v sinh cn rt thp nh cc vng min ni pha Bc (21%), vng duyn hi min Trung (32%), min Ty Nguyn (24%) v c bit rt thp vng ng bng sng Cu Long (19%) (Bng 1.1).

Bng 1.1: T l s dn s dng nc sch v s gia nh c nh v sinh cc khu vc trong nc nm 2001

T l (%) Khu vc S dn s dng

nc sch S gia nh c

nh v sinh Min ni pha Bc 39 23 ng bng sng Hng 50 47 Min Bc Trung b 44 41 Duyn hi min Trung 42 32 Vng Ty Nguyn 36 24 Vng ng Nam b 53 46 Vng ng bng sng Cu Long 48 19

(Ngun: Chng trnh Mc tiu Quc gia Nc sch - V sinh Mi trng Nng thn, 2003)

Mt kho st ti mt s im i din - c ng trn tp ch Nng nghip v Pht trin Nng thn (s 2/2003) - cho thy (Bng 1.2), t 1988 cho n nay, trung bnh mi nm s h nng dn c h x hp v sinh tng chng 2 - 3 %. Bo co cho bit, nm 2002 vng nng thn ca c nc c khong 228.000 h x hp v sinh, 6.000 hm biogas lin hon v 516.000 chung tri chn nui hp v sinh c xy dng.

Bng 1.2: S h nng dn c h x hp v sinh 1998 1999 2000 2001 2002

% s h # 20 # 30 32 34 37 (Ngun: L Vn Cn, 2003)

Cng theo bi bo trn, k hoch nm 2003, c nc s "xy dng thm khong 400.000 h x, 180.000 chung tri chn nui hp v sinh vi tng vn 1.440 t: ngn sch trung ng h tr: 236 t, ngn sch quc t: 387 t v vn huy ng t a phng v ca dn khong 800 t ng" (L.V. Cn, 2003) Mc du s nh v sinh c gia tng hng nm nhng con s trn cng cho thy s lng ny cng cn thp, nht l cc vng su, vng nng thn xa. Cc phn tch sau cho ta bit thm nguyn nhn hn ch dn n ca thc trng vn xy dng v s dng nh v sinh nng thn.

--------------------------------------------------------------------------------------------------------- Chng 1: NH V SINH NNG THN VIT NAM - HIN TRANG V VN

2


1.1.2. Cc nguyn nhn hn ch vic xy dng nh v sinh nng thn Cc khc bit ln nht gia nng thn v thnh th Vit Nam chnh l s

cch bit qu xa v thu nhp, mc sng, iu kin hc hnh, iu kin hng th nc sch, v sinh mi trng, khm cha bnh, i li v hng th vn ha, thng tin, ... Tp qun sng da vo cc iu kin t nhin ca ngi dn nng thn cha c s thay i ln. T nhng hn ch ny, a phn ngi dn nng thn vn cha quan tm n vic xy dng nh v sinh nng thn. S b c th lit k:

Thu nhp thp; Chi ph lm nh v sinh cao; Kh khn v ngun nc; thc v sinh thp; Thi quen i tin ngoi ng, trn sng rch; Khng thch s t tng, cht hp trong nh v sinh; Xem vic nui c bng phn ngi v gia sc nh mt ngun thu nhp; Thi quen lm chung tri gia sc, l st sinh, hp ch st bn knh rch; Cho rng nh v sinh l khng cn tht v; Cha c s quan tm h tr cao ca cc cp chnh quyn.

Trog cc nguyn nhn trn, thu nhp thp v chi ph lm nh v sinh cao l hai nguyn nhn hn ch chnh. Mt phn hoc tng hp cc nguyn nhn trn dn n con s t 19% ngi dn vng ng bng sng Cu long n 47% ngi dn vng ng bng sng Hng cha c nh v sinh nh bng 1.1. Cc con s ny cng l c s gii thch l do dch bnh lin quan n v sinh - ngun nc nng thn Vit Nam kh cao. 1.2 BNH TT LIN QUAN N NGUN NC V THIU NH V SINH

Vic s dng nc s to ra nc thi, nc thi sinh hot v sn xut u mang cc cht c hi nh hng n sc kho con ngi v lm suy gim mi trng. Tnh trng thiu nh v sinh, thi quen i i tin trn sng rch v ng rung ba bi (Hnh 1.2) lm gia tng nguy c nhim bnh trong cng ng. Nhn thy tm quan trng ca vic cp nc v v sinh mi trng, T chc Lin hip quc tuyn b ly thp nin 1981 1990 lm Thp nin Cp nc ung v V sinh Quc t. Tuy giai on ny chm dt gn 15 nm nhng vn vn cn cn thit cc quc gia thuc th gii th ba, c bit l nhng nc chm pht trin v c nhng vng nng thn ca cc quc gia ang pht trin. Ti Vit Nam, hng nm Chnh ph vn pht ng thng Nc sch v V sinh Mi trng, tuy nhin tc dng khng nhiu, nhiu ni ch mang tnh hnh thc v phong tro (Bng 1.3). Mt du c nhiu a phng tm cch ci thin nng cao mc sng ca ngi dn nhng vn nc sch v v sinh mi trng vn cn mang tnh thi s cho tt c cc khu vc khc nhau ca t nc, c bit l cc vng tp trung c dn ng o nhng trnh dn tr cn chm nh vng ng bng sng Cu Long. Mi nm chng ta vn phi i u thng xuyn vi nhng thch thc lin quan n bnh tt v sc kho ca ngi dn.


3


Bng 1.3: Hin trng s dng h x cc th Vit Nam (theo % h gia nh) Thnh ph Loi Min H x c

x nc H x

2 ngn H x thng

Khng c h x

H Ni I Bc 48 18 16 18 Hi Phng II Bc 27 0 23 50 Thi Nguyn III Bc 45 0 24 31 Hi Dng III Bc 55 33 0 12 Bc Giang III Bc 0 0 100 0 H Ch Minh I Nam 91 0 0 5 Nng II Trung 83 4 0 13 Hu II Trung 63 1 0 36 Cn Th II Nam 91 0 0 9 Phan Thit II Trung 36 0 0 64 Nha Trang III Trung 82 0 0 18 (Ngun: Vietnam National Urban Wastewater Collection and Sanitation Strategy,

1995 (http://www.unep.or.jp/ietc/Publications/TechPublications/TechPub-15/3-3AsiaPacific/3-3-1.asp))

Ring i vi mt th ln nh Cn Th, s liu thng k nhiu nm cho thy s ngi c hng iu kin nc sch v v sinh mi trng cng cn rt thp (Bng 1.4). Cc tnh ngho hn vng ng bng sng Cu Long, t l ny cn xung rt thp.

Bng 1.4: S cng trnh lin quan n v sinh mi trng Cn Th Nh v sinh Nc sch Cng trnh khc

Nm

S ngi c

hng iu kin v sinh

T l (%) S gia nh c dng

nc sch

T l (%)

% gia nh c nh tm t iu

kin v sinh

% gia nh c chung

gia sc hp v

sinh

% gia nh c ti gom

rc

1996 57,886 18.26 33,451 11.00 32.00 52.00 45.00 1997 64,904 20.58 35,519 11.68 36.00 60.00 55.51 1998 80,480 25.58 40,556 13.34 40.03 70.00 56.60 1999 80,826 25.69 131,055 43.13 43.03 82.17 58.33 2000 121,188 38.22 156,756 49.41 49.45 86.32 67.73 2001 119,976 37.65 158,323 50.00 51.40 89.47 77.75 2002 67,906 21.31 133,909 42.29 54.07 - 72.40

(Ngun: Hunh Phc Li, Trung tm Y hc D phng tnh Cn th, 2003) Cc bo co khc nhau u ghi nhn c trn 80% bnh ng rut hin nay u bt ngun t ngun nc khng an ton (Bng 1.5 v 1.6). Bradley (1974) v Feachem (1975) phn loi 4 c ch khc bit ca cc bnh lin quan n ngun nc l:

bnh do ung nc b nhim phn (water-borne); bnh do tip xc vi nc bn (water-wasted); bnh do cc sinh vt sng trong nc gy ra (water-based); bnh do cn trng sinh sn trong nc gy ra (water-related insect vector).


4


Hnh 1.2: i tiu ba bi l mt trong cc nguyn nhn gy dch bnh nng thn

Bng 1.5: Phn loi cc bnh lin quan n ngun nc b thiu v nhim

Phn loi truyn bnh V d Ung nc b nhim phn (do lm nh cu, chung tri chn nui x phn, nc tiu, rc rn sinh hot, nc thi khng x l vo ao h, sng rch, ...)

Dch t (Cholera) Kit l do que khun (Bacillary dysentery) Tiu chy (Diarrhoeal) Thng hn (Typhoid) Vim gan siu vi (Hepatitis)

Tip xc vi nc bn da, mt (tm ra, tip xc, lm vic trong mi trng nc bn, ...)

au mt ht (Trachoma) Gh nga (Scabies) Mn cc (Yaws) St do ch rn (Louse-borne fever) Bnh phong hi (Leprosy) Nm da (Tinea)

Nhim sinh vt sng trong nc xm nhp qua da (tm, i chn khng, vt thng ngoi da, ...) vo bng (do n khng nu k cc loi c, s, c, hu, tm, cua, rau, rong bo, ...)

Bnh sn mng (Schistosomiasis) Giun li (Guinea worm) Giun mc (Ankylostrioni) Sn dy (Clonorchirs) Sn (Diphyclobothisas)

Do cn trng sinh sn trong nc (mui, rui, bm, su b, ...) chch ht

Bnh bun ng (Sleeping sickness) St rt (Malaria) St xut huyt (Dengue fever) St vng da (Yellow fever) Vim no Giun ch

Bng 1.6: S bnh tt lin quan n ngun nc b nhim bn Cn Th

Dch t Kit l St thng hn

Vim gan siu vi B

Tiu chy St xut huyt

Nm

Nhim Cht Nhim Cht Nhim Cht Nhim Cht Nhim Cht Nhim Cht 1996 15 0 271 0 1446 0 17 0 51987 6 1498 9 1997 0 0 249 0 1783 0 78 0 41425 2 5411 39 1998 1 0 246 0 1649 0 43881 3 3001 13 1999 0 0 264 0 663 0 5 0 39950 2 1847 10 2000 0 0 662 0 435 0 48 2 11531 0 598 2 2001 0 0 430 0 426 0 57 4 32531 1 628 3 2002 1 0 476 0 313 1 32 3 37013 0 280 2

(Ngun: Hunh Phc Li, Trung tm Y hc D phng tnh Cn th, 2003) --------------------------------------------------------------------------------------------------------- Chng 1: NH V SINH NNG THN VIT NAM - HIN TRANG V VN

5


1.3 THNH PHN PHN V NC TIU NGI Lng phn thi mi ngi hng ngy dao ng vo khong 100 - 400

gram (Bng 1.7) hoc xp x 0,06 m3/nm. Mt nghin cu khc ca J.Aa. Hansen and J.C. Tjell (1982) so snh thnh phn nc thi sinh hot v thnh phn kim loi trong phn ngi v gia sc (Bng 1.8). Cng theo tc gi trn, ngi trng thnh mi nm thi ra chng 400 - 500 lt nc tiu (cha 5 kg nitrogen, 0.4 kg phosphate v 0.9 kg posstasium) tng ng vi 50 - 60 lt phn (cha 0.1 kg nitrogen, 0.2 kg phosphate v 0.2 kg posstasium).

Bng 1.7: Thnh phn phn v nc tiu ngi

Thnh phn Phn Nc tiu Trng lng (ti) (g/ngi/ngy) Trng lng (kh) (g/ngi/ngy) m % Cht hu c (% trng lng kh) T l C/N BOD5 (g/ngi/ngy)

100 400 30 60 70 85 88 97 6 10 15 - 20

1000 - 1310 50 70 93 96 65 85

1 10

(Ngun: Gotaas (1956), Feachem et al. (1983), trch bi Chongrak P., 1989)

Bng 1.8: Hm lng cc cht dinh dng v kim loi nng ha tan trong nc thi, trong phn ngi, trong phn gia sc v trong t t nhin

Cht ha tan

n v Nc thi ng cng

Trong phn ngi

Trong phn gia sc

Trong t t nhin

N P K

Ca Mg Zn Cu Ni Cd Pb Hg

kg/ton kg/ton kg/ton kg/ton kg/ton g/ton g/ton g/ton g/ton g/ton g/ton

30 20 2

25 4

1750 250 20 7

300 5

250 35 45 30 7

200 30 2

0.4 1

0.5

25 10 17 12 4

100 - 800 20 - 350 1 - 36

0.3 5 - 15

-

1 - 2 0.4 0.5 25 7 26 8 5

0.2 17

0.05 (Ngun: J.Aa. Hansen v J.C. Tjell, 1982, trch bi Jacob Vester)

Bng 1.9: So snh thnh phn ha hc ca phn, nc tiu ca ngi v gia sc

Hm lng theo % trng lng Loi cht thi P2O5 K2O N Phn heo Nc tiu heo Rc thi sinh hot Phn chung heo Phn ngi Nc tiu ngi Phn ln nc tiu ngi

0,45 - 0,6 0,07 - 0,15

0,60 0,25 0,50 0,13

0,20 - 0,4

0,32 - 0,50 0,2 - 0,7

0,60 0,49 0,37 0,19

0,2 - 0,3

0,5 - 0,6 0,3 - 0,5

0,60 0,48 1,00 0,50

0,5 - 0,8 (Ngun: Nguyn ng c, ng c Hu (1968), Bi Thanh Tm (1984)

trch bi Trn Hiu Nhu, 2001)


6


Bng 1.10: So snh thnh phn ha hc cc loi phn hu c

Thnh phn (%) Loi phn Mc N P2O5 N2O

Tru Max. Min. Avg.

0,358 0,256 0,306

0,205 0,115 0,171

1,600 1,129 1,360

B Max. Min. Avg.

0,380 0,302 0,341

0,294 0,164 0,227

0,992 0,924 0,958

Heo Max. Min. Avg.

0,861 0,537 0,669

1,958 0,932 1,194

1,412 0,954 1,194

Phn rc Max. Min. Avg.

0,200 0,450 0,840

0,900 0,450 0,850

0,600 0,350 0,580

(Ngun: CINOTECH, Trung tm Khoa hc T nhin TP. HCM, 1995) Cc bng ny cho thy trong phn v nc tiu ngi c thnh phn N-P-K kh cao, hn hn phn gia sc, nc thi v trong t t nhin. Lng nc chim t l khong 70 - 85% khi lng phn. Trong phn ngi lng Carbon gp 6 10 ln lng Nit (C/N = 6 10), nu so snh vi t s C/N thch hp cho qu trnh sinh hc trong khong 20 30 th C/N trong phn ngi l thp hn. T l ny c th iu chnh nu ta c phng php phn hay ln men ym kh thch hp. Nc tiu c thnh phn m N cao hn rt nhiu nu so snh vi phn. Chnh v vy mt s h nng dn c th s dng cht thi ngi hoai, c bit l nc tiu, lm phn bn cho cy trng hoc dng nui c, nui giun t, Trong mt d n v nh tiu sinh thi VinaSanres, Vin Pasteur Nha Trang phn tch thnh phn N, P v K trung bnh ln lt trong nc tiu (ca 10 ngi thuc cc gia nh nng dn ti Cam Ranh cc tui khc nhau) l 4,6 - 0,4 - 4,2 g/l. Theo tnh ton, mi nm mt h c 5 ngi s thi ra mt lng m tng ng vi 25 kg ur tinh khit hoc 43 kg amoni sunfat (SA) tinh khit, cha k lng Kali Photpho i cng. Nit trong nuc tiu nm di dng ur v amoni l dng m cy trng d dng hp thu (Dng Trng Ph, 2003). Tuy nhin cng d nhn thy yu t ny cng l mi trng thun tin cho cc loi vi khun, giun sn v cc loi mm bnh d dng pht trin v ly lan cc dch bnh. L do chnh dn n s ly nhim bnh c th l do cch thc thu gom, qu trnh vn chuyn, kh nng ri vi, v tr tch tr v phng php phn v s thn trng v sinh ca bn thn ngi dn.


7


1.4 MC TIU NGHIN CU 1.4.1 Lc kho ti liu trong v ngoi nc Nh v sinh l tn gi chung ch ni cho cc h gia nh hoc cng ng s dng tp trung x b cht thi ca ngi v dng cho cc nhu cu v sinh khc nh tm, ra, Ty ni, ty ch ngi ta c th c cc tn gi tng t nh: cu tiu, nh tiu, h x, nh x, toilet, WC (Water Closet), Tn gi ny cng c s dng chung trong tp nghin cu ny v hu nh c ngha tng t vi nhau. T trc n nay, vic nghin cu thit k cc mu nh v sinh nng thn rt t c cp trong nc. Trong khong thi gian 1997 - 2000, t chc SIDA ca Thy in c mt d n hp tc vi B Y t - Vin Pasteur Nha Trang gii thiu mt loi hnh nh v sinh sinh thi Vinasanres. D n nghin cu la chn t 5 kiu nh v sinh th im khc nhau Vit Nam. Loi nh v sinh Vinasanres p dng mt s tnh thnh min Bc, min Trung v mt s vng min Nam. Theo Dng Trng Ph (2003), thng tin v k thut nh v sinh ny c gii thiu ti liu Thng tin Y t D phng s 1/2001 v S tay Xy dng v S dng Nh tiu Sinh thi Vinasanres (2003) do Vin Pasteur Nha Trang xut bn, tp san Nc sch v V sinh Mi trng s 1-1/2002 v s 5-3/2003 ca Trung tm Nc sch v V sinh Mi trng Nng thn v trong tp sch Nh tiu cho Nng thn Vit Nam (2003) ca Nh xut bn Y hc. Mt s tc gi khc nh ThS. L Anh Tun (2000) trnh by mt phn thit k Nh v sinh nng thn trong Gio trnh Cng trnh X l Nc thi (i hc Cn Th), GS.TS. Trn Hiu Nhu v cc cng s (2001) c trnh by mt s kiu nh v sinh trong quyn Cp nc v V sinh Nng thn (Nxb. Khoa hc & K thut). Ngoi ra cn c mt s bi bo, tp ch, tp san ri rc trong c nc cng trnh by mt s kiu nh v sinh n gin nng thn. nc ngoi, phi k mt s ti liu lin quan n nh v sinh nng thn nh ca cc tc gi Richard Feachem, Michael McGarry, Duncan Mara (1978) vi tc phm Rural Water Supplies and Sanitation (Nxb. Mac Millan Press); Uno Winblad (1978) vi tc phm Sanitation Without Water (Preliminary Edition); Peter Morgan (1994) vi Water, Wastes and Health in Hot Climates (Eng. Lang. Book Society anh John Wiley & Sons Chichester). Quyn Low-Cost Technology Options for Sanitation - A State of the Art Review and Annotated Bibliography (International Development Research Centre) ca nhm tc gi Witold Ryberyski, Chongrak Polprasert v Micheal McGarry (1978) l mt ti liu lc kho kh nhiu cc kiu nh v sinh r tin, thch hp cho vng nng thn. Ngn hng Th Gii (The World Bank - WB) ti tr cho nhm tc gi John M. Kalbermatten, DeAnne S. Julius, Charles G. Gunnerson v D. Duncan Mara (1982) bin son ti liu Appropriate Sanitation Alternatives - a Planning and Design Manual, y l mt cm nang kh hu ch cho cc nh ra quyt nh v nh k thut trong vic la chn cc phng n xy dng nh v sinh. Mt s nghin cu lin quan n nh v sinh ni chung v nh v sinh nng thn cng c ng ri rc mt s website trn Internet (xem ti liu tham kho). Trn web cng c mt mn hc lin quan n nh v sinh (Toiletology, hnh 1.3). T chc Toilet th gii (World Toilet Organization) l mt t chc quc t c mc tiu trao i ph bin thng tin lin quan vic xy dng v s dng nh v sinh. T chc ny c tr s ti Singapore v Vit Nam cng l mt thnh vin ca t chc ny (Hnh 1.4). Cc ti liu trn c gi tr ng dng trin khai cho cc vng nng thn c th. --------------------------------------------------------------------------------------------------------- Chng 1: NH V SINH NNG THN VIT NAM - HIN TRANG V VN

8


Welcome to the Toilet Repair Lessons: Toiletology 101 ... A Free Course on Toilet Repairs to Save Water and Money

Click Here Water

Management, Inc.

The leader in Water Efficiency Programs since 1980

A Toiletology 101 sponsor since 1998

Photo by Ken Heinen

The Care and Repair of Toilets

Hnh 1.3: Mn hc Toiletology trn http://www.toiletology.com

Hnh 1.4: Trang web ca T chc Toilet th gii

http://www.worldtoilet.org/ --------------------------------------------------------------------------------------------------------- Chng 1: NH V SINH NNG THN VIT NAM - HIN TRANG V VN

9


1.4.2 Cc ch trng v chnh sch ca Quc t v Chnh ph C th lit k cc ch trng v chnh sch ca cc t chc quc t v Nh nc lin quan n vn nc sch v v sinh mi trng sau:

T chc Lin hip quc tuyn b ly thp nin 1981 1990 lm Thp nin Cp nc ung v V sinh Quc t.

Lin hip quc (1992) chnh thc chn ngy 22 thng 3 hng nm lm

ngy "Quc t v nc" nhm nhc nh mi ngi quan tm hn v ngun nc.

Ti Vit Nam, Chng trnh nc sch v v sinh mi trng c

UNICEF ti tr t 1982 n nay. Chng trnh ny tp trung gii quyt vn nc sch vng nng thn.

Ngy 03/12/1998, Th tng Chnh ph ra Quyt nh s 237/1998/Q-

TTg ph duyt Chng trnh mc tiu quc gia nc sch - v sinh mi trng nng thn v giao cho B Nng nghip v Pht trin nng thn ch tr, phi hp vi cc B, Ngnh, a phng trin khai.

Chin lc Quc gia Cp nc sch v V sinh Nng thn n nm 2020

c Th tng Chnh ph chnh thc ph duyt (Quyt nh s 104/2000/Q-TTg ngy 25/8/2000) v ang c trin khai rng ri trn ton b cc tnh thnh c nc. Mc tiu c th ca chin lc l:

Mc tiu ti nm 2010: 85% dn c nng thn s dng nc hp v

sinh vi s lng 60 lt/ngi.ngy, 70% gia nh v dn c nng thn s dng h x hp v sinh v thc hin tt v sinh c nhn.

Mc tiu ti nm 2020: tt c dn c nng thn s dng nc sch

t tiu chun quc gia vi s lng t nht 60 lt/ngi.ngy, s dng h x hp v sinh v thc hin tt v sinh c nhn, gi sch v sinh mi trng, lng, x.

Thng 7/2002, Chnh ph ban hnh Quyt nh s 99/2002/Q-TTg v vic

chuyn Chng trnh mc tiu quc gia nc sch - v sinh mi trng nng thn thnh Chng trnh mc tiu quc gia c tm quan trng c bit ca chnh ph, m rng thm hai nhim v l bo m nc sch v bo v mi trng nng thn. Chng trnh ny cng c lng ghp vi cc Chng trnh v D n thuc qun l ca B Nng nghip v Pht trin Nng thn nh di dn, xy dng vng kinh t mi, nh canh, nh c, xy dng c s h tng nng thn v cc Chng trnh do cc B, Ngnh khc qun l nh Chng trnh Xa i gim ngho, xy dng cc cm dn c min ni.

Cc b lut lin quan:

+ Lut bo v sc kho nhn dn (1989) + Lut pht trin v bo v rng (1991) + Lut bo v mi trng (1993)


10+ Lut ti nguyn nc (1998)


1.4.3 Thuyt minh s cn thit ca ti Hin nay, trn 60% c dn nng thn Vit Nam khng c h x hp v sinh v mi trng. Nguyn nhn chnh l do nhn thc km v thu nhp thp hn ch vic s dng h x hp v sinh (xem phn 1.2.3). Chnh s hn ch ny cng thm cc thiu thn ti liu v cn b k thut hng dn, vic vn ng xy dng cc nh v sinh hp l gp t nhiu kh khn. Do vy, ti nhm bin son ti liu ph bin phc v nng thn Vit Nam, c bit h tr cho Chng trnh Nc v V sinh Nng thn ca Chnh ph Vit Nam. 1.4.4 Mc tiu ca ti 1.4.4.1 Mc tiu tng qut Mc tiu tng qut ca ti l bin son mt tp ti liu gii thiu cc mu nh v sinh. Cc mu nh ny c th l kt qu tng hp cc nghin cu trc v c iu chnh cho ph hp cho tnh hnh nng thn a phng. 1.4.4.2 Mc tiu c th

Tp hp cc d liu lin quan n nh v sinh nng thn; Phn loi nh v sinh nng thn theo chc nng s dng v x l; Vai tr ca nh v sinh trong sc kho cng ng; Cc kiu thit k nh v sinh khng dng nc nng thn; Cc kiu thit k nh v sinh c dng nc nng thn; Cc ch tiu k thut lin quan n xy dng nh v sinh nng thn;

1.4.4.3 Tiu ch Tiu ch cho vic thit k:

R tin, ph hp vi mc thu nhp trung bnh - kh ca nng h. Hp v sinh, t cc yu cu v v sinh mi trng v hn ch ti thiu

s ly lan cc mm bnh cho cng ng. D xy dng, d sa cha: ngi dn nng thn vi mt s s hng

dn ca cc b k thut c th t lm cho mnh hoc cho cng ng. Tn dng vt liu a phng: cc vt liu xy dng nh v sinh u c

th kim d dng u khu vc nng thn. Mt s vt t khc c th phi mua thnh ph hoc cc ca hng vt liu xy dng cp huyn, th x hoc ch th trn.

Hon ton s dng lao ng ti ch, khng cn phi thu mn th t cc a phng khc.

Ph hp vi kh nng qun l qui m gia nh v cng ng.

1.4.5 Kh nng ng dng kt qu ca ti Vic ng dng v trin khai kt qu ca ti liu ny s ph thuc vo nhiu yu t nh mc ph bin rng ti liu, s quan tm tuyn truyn ca cn b a phng, kinh ph h tr cho vic thc hin v quan trng hn l s ng tnh ca ngi dn. Tuy nhin, cng c nhiu k vng cho vic p dng kt qu ca ti ny nu c s h tr kinh ph v nhn lc trong vic ph bin k thut.


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Thit k nh hnh cc mu nh v sinh nng thn ThS. L Anh Tun ------------------------------------------------------------------------------------------------------------

KIN THC C S V d NH V SINH NNG THN =============================================================== 2.1 MT S NGUYN TC C BN I VI NH V SINH 2.1.1 B tr Nh v sinh

cc vng nng thn, ni c din tch rng ri, kinh ph v vt liu xy dng kh khn, nh v sinh thng b tr bn ngoi nh , mang tnh cng ng (cho 1 hoc vi nng h s dng chung), cu trc n gin nhng m bo yu cu v sinh mi trng, mt s khong cch ti thiu hnh 2.1 cn c tham kho.

NH

% NGUN SNG , > 8 - 30 m

> 1,5 2,0 m MC NC NGM (tng trn)

# 4 - 6 m > 8 - 30 m

-

CC NGUN NC KHC

> 8 - 30 m

GING NC

WC

Hnh 2.1: Khong cch ti thiu tham kho khi b tr h x cng cng vng nng thn

Nh v sinh cng cng nn b tr ni thp nht, cn cch xa ging v cc ngun nc khc t nht l 8 m i vi vng ng bng v n 30 m i vi vng ni, vn cao nguyn. Hng chy ca nc ngm phi chy theo hng t ging n x trnh nc thi ngi chy vo ging. y h x phi cao hn mc n ngm tng trn ti thiu khong 1,5 n 2,0 m. Ch tiu ny, trong mt s iu kin no vng ng bng Sng Cu Long tng i kh t, c bit l c c vng ngp l, nhng ni m nc cao hn mt t t nhin hn 1 mt v

-----Ch g hc

-------------------------------------------------------------------------------------------------- ng 2: KIN THC C S V NH V SINH NNG THN

12


ko di vi ba thng lin tc. Tuy nhin, chng ta cng c th chp nhn s nhim bn tm thi cho nhng vng ny nu cha c cc kinh ph cn thit xy dng cc nh v sinh t hoi chc chn v c nh. Trng hp ny, vi khi lng nc l qu ln th xem kh nng s pha long, s tiu th phn ca c t nhin v kh nng t lm sch ca thin nhin l cao. 2.1.2 Phn loi nh v sinh C 3 dng chnh chn la khi quyt nh xy dng nh v sinh:

Bng 2.1: Phn loi nh v sinh theo nguyn l x l phn Tnh cht Dng

nh v sinh Nguyn l x l phn u im Nhc im

T hoi

Vi khun ym kh s phn hy cc cht thi ngi sau mt thi gian trong b t hoi.

Sch s, gn gng, khng hoc t gy r r mi hi

Thch hp cho nhng vng t cao, t ph sa nc ngt.

Chi ph cao. Khng th dng

nc mn v nc phn c v cc loi nc ny khng gip cho phn t hoi c.

T thm

Cht thi thm qua cc tng t v t lm sch

Thch hp cho cc vng t thm nc tt nh cc vng cao, vng i ni, vng ging ct ven bin

c UNICEF xut xy dng kh nhiu ni kh hn.

C th nh hng phn no i vi nn t ni t nh v sinh.

Dng kh

Dng ny khng dng nc, thng dng tro bp, tro tru hoc ct mn ph lp phn.

C th thit k phn v nc tiu i n nhng thng cha ring bit.

R tin Phn ngi sau

mt thi gian trn vi tro bp c th dng lm phn bn cho cy trng.

Khng c v sinh v thm m

C mi hi Nu khng che y cn thn, rui c th n sinh sn.

Khi xt n vic c hay khng s chuyn vn phn i ni khc kt hp vi kh nng c hoc khng c nc di cu th ta c th theo s khuyn co Bng 2.2 v 2.3:

------------------------------------------------------------------------------------------------------- Chng 2: KIN THC C S V NH V SINH NNG THN

13


Bng 2.2 : Phn loi b thi lin quan s dng nc v vn chuyn phn C s vn chuyn phn Khng vn chuyn phn

C dng nc 1. Xy dng nh v sinh loi c nt nhn x nc ni vi h thng dn thot nc

3. Xy dng loi nh v sinh c nt x ni h cha phn hoc ao c hoc hm biogas

Khng dng nc

2. Xy dng loi nh v sinh vi loi h x thng

4. Xy dng loi nh v sinh vi h phn compost

Bng 2.3: Cc hnh thc chuyn phn

Hnh thc vn chuyn c im

Vn chuyn phn bn bng xe ht hm cu

Ph hp vi cc vng th v ven , th trn

Chi ph cao V sinh tt

Vn chuyn phn bng cng lao ng (ngi co v xe y)

Ph hp vi vng nng thn v vng ni, ni khan him nc

Tit kim phn bn Thiu v sinh

Vn chuyn phn bng thng Ph hp vi vng nng thn v

vng ni, ni khan him nc Tit kim phn bn Thiu v sinh

Vn chuyn phn bng thng dng c gii

Ph hp vi vng nng thn v thnh th

C th lm phn bn V sinh mc va


14


Nu xem xt n vic vn chuyn, x l v ti s dng phn th c th theo s hnh 2.2 sau. Quan h ny l mt phn ca m hnh canh tc sinh thi khp kn VACB (Vn - Ao - Chung - Biogas) nng thn.

c

Nui tru, b, d,

Ngi

Thc phm

S D

NG

&

TI S

D

NG

V

N C

HU

YN

&

X

L

TH

U G

OM

Nui g, vt

Ti, bn rung/ Trng c

Ao trH tr

Nui to

Nui trn

Nui H Biogas

Xe ht hm cu

Xe b chuyn phn

Cng rnh

B cha phn/B t hoi

Hm c nh

H tm

Thng cha

Xung ao, h * Dng ncKhng dng nc

H X

Hnh 2.2: M hnh VACB lin quan n vic s dng h x Ghi ch: * Nh x thi cht bi tit xung ao h (nh nh x ao c), trong mt s phn loi, c xem l loi nh x khng dng nc. Ngoi ra ngi ta cn phn loi theo kiu nh x c hay khng s chia tch phn v nc tiu cho cc mc tiu x l v s dng khc nhau.


15


Nh x khng c s chia tch nc tiu (non-urine-diverting units) Loi nh x ny gi phn v nc tiu cng mt h x, y cng l mt kiu thng dng nhiu ni, k c vng nng thn hoc thnh ph. Nu c yu cu phn th chuyn tt c cc cht thi ngi thnh t mn bng cch ph ln chng vi, tro cy, t bt, rm mc, sau mi ln i tiu tiu. Thi gian thng t nht 3 - 4 thng. Nu c h thng thng hi th c th rt ngn xung cn khong 2 thng. Hu ht loi ny c hm cha t di mt t v phn - nc tiu t hoi v c kt cu hm nh sau (Hnh 2.3).

Hnh 2.3: Kt cu hm cha phn v nc tiu

Nh x c s chia tch nc tiu (urine-diverting units) Loi nh x ny tch phn v nc tiu i thnh 2 con ng ring bit. Phn c dn theo mt ng ng vo hm x, Hm ny c th trong 3 - 4 thng. Cn nc tiu c dn i theo mt ng ng ring ra ngoi x l cho hoai khong vi ngy v ho vi nc, dng ti cho cy trng. B ngi x c kt cu c bit c s chia tch ny. (Hnh 2.4).

Hnh 2.4: Kt cu mt b ngi vi s chia tch phn v nc tiu


16


Hnh 2.5: Mt kiu b x n gin c s chia tch phn v nc tiu

theo thit k ca Trung tm Cng ngh Nh v sinh Gramalaya (Gramalaya Toilet Technology Centre), n

Phn phn thng c x l theo tin trnh chung nh: lm kh, gia tng pH (thm alkaline t tro, tru, ) v tng nhit . Phn nc tiu th dn cha mt b ring, y kn ngn kh nitrogen tht thot, yn trong vi ngy n 1 tun cho "hoai", lc nc tiu chuyn thnh amonia v pH tng ln khong 9, hu ht cc mm bnh b dit. Pha nc tiu "hoai" vi nc sch t l 1:5 n 1:10 khi ti cho cy trng.

Hnh 2.6: Minh ha mt kiu nh tiu nng thn

c s phn tch phn v nc tiu ED-CTU, 2003)

-----Ch (Ngun: Thilo, SANS-------------------------------------------------------------------------------------------------- ng 2: KIN THC C S V NH V SINH NNG THN

17


Nh x ci tin s tch nc tiu, phn v mi hi: c c mt kiu nh x ci tin: phn v nc tiu c nhn vo chung mt b cha. B cha ny c th trn mt t. b cha li lm mt li lc nc. Nc tiu v mt phn nc dch t phn thm xung di v c dn ra ngoi bng mt ng dn ring, phn phn ro nc hn c gi li pha trn t hoi hoc ly ra ngoi bng mt ca ring. Phn kh c mi hi c rt xung phn cha nc v c dn cng bc ra mt ng ng ring a ln cao bng mt qut ht kh (Hnh 2.7).

Hnh 2.7: Mt kiu nh v sinh ci tin c: phn, nc, kh tch bit.

2.2 YU CU XY DNG MT NH V SINH Tiu chun chnh ca mt nh v sinh phi m bo v sinh mi trng. Bn cnh cn c nhng tiu chun khc lit k ra nh sau:

Phi m bo v sinh mi trng, khong cch t nh v sinh n cc ngun nc t 8 30 mt, cch ch phi xa (ti thiu 4 6 mt).

Khng mi hi, x u thot ra chung quanh. Nc t hm nh v sinh khi thot ra phi sch, m bo yu cu ngun

nc loi B (theo tiu chun Vit Nam, xem ph lc), v l thuyt khng c vi khun gy bnh.

Hm cu bo m chc chn, an ton cho ngi s dng. i vi cc dng nh v sinh cn c mt p lc nc mnh tng

sch cc cht thi xung b cha. i vi cc gia nh ngho th nn b tr cc x nc, thng di c dung tch khong 20 lt tng cht thi.


18

Trong nh v sinh nn thm cc chi chi bng tre hoc nha, thng ng giy v sinh, khay x phng, lu cha nc.


Kch thc h cha phn phi ln t nht c thi gian s dng trn 3 nm (i vi vng nng thn) v trn 5 nm (i vi cc khu dn c, th) mi y v phi thu cc xe ht hm cu n rt cc cht cn b.

Nh v sinh phi kn o, sch s, thong kh v phn no to s thoi mi, tin li cho ngi s dng.

Thng thng nh v sinh va l ni x cht thi ngi v cng l ni nh tm. Cn ch l khi thit k nn lm ng dn nc thot ring bit. Nc tm tuyt i khng cho chy vo h x v c cha nhiu cht ty ra, x phng gy nguy hi cho cc vi khun ym kh trong hm t hoi.

2.3 QUI M XY DNG NH V SINH Qui m xy dng nh v sinh c hiu l dung tch cn thit ca h cha phn hay kch thc h cha, dung tch cha ca nh v sinh ty thuc vo 3 yu t: mc thi ca tng c nhn (ngi ln hoc tr em), s lng ngi s dng nh v sinh v thi gian s dng (thi gian phi ht sch hm cu). Tht s, kh c th xc nh chnh xc dung tch ny, n mang tnh gn ng, vic tnh ton thin v an ton, ngha l kt qu tha so vi nhu cu thc t. Th tch h cha phn c th xc nh theo (Kalbermatten et al., 1980):

Nu kch thc h cha nh hn su 4 m (Cng thc 2-1):

V = A.d = 1.33 x C.P.N

Nu kch thc h cha ln hn su 4 m (Cng thc 2-2):

V = A.(d - 1) = C.P.N Trong : V = th tch h cha phn (m3) C = mc thi phn (m3/ngi.nm). Ly theo bng 2.3. P = s ngi s dng (ngi) N = thi gian s dng (nm) A = din tch mt ct ngang h o (m2) d = su h o (m) H s 1.33 c xem l h s gia tng an ton 30% cho th tch h cha phn.

Bng 2.4: Mc thi phn theo m3/ngi.nm H cha t H cha kh

Dng nc ra sch hu mn

Dng giy chi sch hu mn

Dng nc ra sch hu mn

Dng giy chi sch hu mn

0.04 0.06 0.06 0.09 (Ngun: Kalbermatten et al., 1980)


19


V d 2.1: (theo ti liu ESIC, Bangkok, 1987) Mt gia nh 6 ngi cn mt h cha chi ph thp. t trong khu vc l loi t c thm rt thun li v n nh. Mc thy cp l 7 m di mt t. Xc nh kch thc h cha phn cho yu cu s dng 10 nm trong 2 trng hp: h hnh tr trn v h hnh khi ch nht. Lu rng gia nh dng nc ra hu mn sau khi i tiu. Gii: Theo cng thc (2-1): V = 1,33 x C.P.N = 1,33 x 0,06 x 6 x 10 = 4,8 m3

H cha phn nu lm theo hnh tr trn, ng knh hnh tr thng c chn vo khong 1,0 - 1,5 m. Chn ng knh 1,25 m th su ca h cha phn l:

Th tch h su ca h cha phn =

Din tich chung quanh h hnh tr

Din tich chung quanh h = 2D4

= 21,254

3.1416 = 1,23 m2

su ca h cha phn = 23,18,4 = 3,91 m

Bng 2.5 v 2.6 l bng tnh th tch cho cc h cha kh (h x khng di nc) v h cha t (h x c di nc) theo cng thc 2-1.

Bng 2.5: Th tch h cha kh Th tch (m3)

S ngi s dng Dng nc ra sch hu mn

S ngi s dng Dng giy chi sch hu mn

S nm s dng (nm)

4 6 8 10 12 4 6 8 10 12 4 1,28 1,92 2,56 3,20 3,84 1,92 2,88 3,84 4,60 5,32 6 1,92 2,88 3,84 4,60 5,32 2,80 4,20 5,32 6,40 7,48 8 2,56 3,84 4,84 5,80 6,67 3,84 5,32 6,67 8,20 9,64

10 3,20 4,79 5,80 7,00 8,20 4,60 6,40 8,20 10,0 11,8 12 3,84 5,32 6,76 8,20 9,64 5,32 7,48 9,64 11,8 13,9615 4,60 6,40 8,20 10,0 11,8 6,40 9,10 11,8 14,5 17,2

(Ngun: ESIC, Bangkok, 1987)


20


Bng 2.6: Th tch h cha t Th tch (m3)

S ngi s dng Dng nc ra sch hu mn

S ngi s dng Dng giy chi sch hu mn

S nm s dng (nm)

4 6 8 10 12 4 6 8 10 12 4 0,85 1,28 1,71 2,13 2,56 1,28 1,92 2,56 3,20 3,88 6 1,28 1,92 2,5 3,20 3,83 1,92 2,88 3,84 4,60 5,32 8 1,71 2,56 3,41 4,20 4,84 2,56 3,84 4,84 5,80 6,76

10 2,13 3,20 4,20 5,00 5,80 3,70 5,80 5,80 7,00 8,20 12 2,56 3,84 4,84 5,80 6,76 3,84 6,76 6,76 8,20 9,64 15 3,20 4,60 5,80 7,00 8,20 4,60 8,20 8,20 10,0 11,9

(Ngun: ESIC, Bangkok, 1987) Bng sau cho th tch h cha phn theo mt ct ngang v chiu su, tnh theo cng thc 2 - 2.

Bng 2.7: Th tch h cha phn theo kiu v kch thc Th tch h cha phn (m3) Kiu v kch

thc Chiu su 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

Hnh trn, 1,00 m 0,785 1,18 1,57 1,96 2,36 2,75 3,14 3,66 4,18 Hnh trn, 1,25 m 1,23 1,84 2,45 3,07 3,68 4,29 4,91 5,71 6,53 Hnh trn, 1,50 m 1,77 2,65 3,53 4,42 5,30 6,18 7,07 8,22 9,40 Hnh vung, cnh 1,00 m 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,66 5,32 Hnh vung, cnh 1,25 m 1,56 2,34 3,13 3,91 4,69 5,47 6,25 7,28 8,31 Hnh vung, cnh 1,50 m 2,25 3,38 4,50 5,63 6,75 7,88 9,00 10,48 11,97

(Ngun: ESIC, Bangkok, 1987) (Cc bi m trong bng trn l dng cho v d 2.2) V d 2.2: (theo ti liu ESIC, Bangkok, 1987) Nh v d 2.1, dng bng tra xc nh th tch v hnh dng h cha. Gii: Tra bng 2.5 cho h x kh, vi 6 ngi trong h v s dng h cha 10 nm, dng nc ra hu mn, ta c th tch thit k l 4.79 m3. S dng bng 2.6 vi th tch 4.79 m3, ta c cc chn la cc kiu h cha sau (xem cc bi m, chn s gn 4.79 m3, nghing v an ton):

H trn: ng knh 1,25 m x chiu su 4,0 m H trn: ng knh 1,50 m x chiu su 3,0 m H vung: cnh 1,00 m x cnh 1,00 m x chiu su 5,0 m H vung: cnh 1,25 m x cnh 1,25 m x chiu su 3,0 m (th tch hi ht) H vung: cnh 1,50 m x cnh 1,50 m x chiu su 5,0 m


21


Ta cng c th s dng ton sau (hnh 2.8) xc nh th tch h cha: on OA - Thi gian s dng (nm) on OB - Mc thi phn (m3 /ngi.nm), ly bng 2.3. on OC - Th tch h cha (m3) on DE - S ngi s dng (ngi)

4,8

N

T

P

Th

tch

(m3 )

S n

g

i s

dn

g (n

g

i)

14 12 10

6 8

1415

1213

1011

89

4567

3

2 4

12

OD 0.09 0.06 0.04

Mc thi phn (m3/ngi.nm)

C

E

B

A

180 10 12 14 166 8

S nm s dng (nm) 2 204

Hnh 2.7: Ton xc nh th tch h cha phn (Ngun: ESIC, Bangkok, 1987)

V d 2.3: Dng v d 2.1, s dng ton xc nh th tch h cha phn. Gii:

1. Chn im C. T bng 2.4, mc thi phn l C = 0,06 2. Chn im P, l s ngi s dng, v d ny l 6. 3. Ni CP c im T trn on OB. 4. K ng ni 2 im A v T c on AT. 5. Chn im N, l s nm thit k, y l 10 nm. 6. T im N, ko thng ln gp on AT, t im giao, ko ngang qua

on OB, im ct trn on OB l th tch thit k: # 4,8 m3.


22


Mt nghin cu khc Vit Nam, mc thi phn v nc tiu theo bng 2.8.

Bng 2.8: Mc thi phn v nc tiu hng ngy ca ngi Phn (grams) Nc tiu (lt) Ngi ln: Nam

N150 145

1.50 1.35

Tr em: Nam N

- -

0.57 0.35

(Ngun: Tuan, V.A. & Tam, D.M., 1981) Theo nghin cu ca Vin Pasteur Nha Trang, c tch th tch ngn cha phn qui m gia nh, c th dng cng thc kinh nghim sau (Dng Trng Ph, 2003):

Th tch ngn cha V (m3) = S ngi trong h x 0.04

Cng thc ny cng tng i ph hp vi mc thi phn theo s liu bng 2.3 ca Kalbermatten et al. (1980). Theo quan im an ton, mi ngi trong mt ngy thi ra chng 100 - 400 gram phn ti v khong 1 - 1.3 lt nc tiu (theo bng 1.2, Chng 1) hoc xp x 0,06 m3/nm. H tp trung phn dnh cho mt gia nh trung bnh t 4 - 6 ngi trong 5 nm, cn c th tch cha khong 1,5 m3 - 1,8 m3 (o su 1,5 - 1,8 m 0,5 m, y rng 1 x 1 m2). Nu c iu kin nn xy thnh xi mng - gch ngn mt phn nc phn tiu thm vo t. Nu chn la vic xy dng cc nh v sinh tp th cho nhng ni ng ngi c tnh cht cng ng nh trng hc, hp tc x, xng sn xut tp th, lng x, th tt hn ht cn phi lm nh v sinh kiu h t hoi v c th tham kho bng 2.9:

Bng 2.9 : Dung tch b cha cht thi theo kt cu

Loi b S ngi s dng

Dung tch

B t hoi 2 ngn B t hoi 3 ngn B t hoi nhiu ( > 3) ngn B phn hy

15 20 20 50

> 50 4 - 200

3.000 - 4.000 lt 4.000 - 10.000 lt

S ngi x 1.000 lt/ngi S ngi x 1.000 lt/ngi


23


2.4 CU TRC C BN V TN GI CC B PHN MT NH V SINH Nh v sinh kiu t hoi tng i ph bin Vit nam, c thnh th ln nng thn. Mt nh v sinh phi c cc thnh phn c bn sau (Hnh 2.9).

ng thot nc

B cha phn

Co kha nc B

Bn cu

ng thng hi

Nh bao che

Hnh 2.9 : Cc b phn c bn ca mt nh v sinh 2 ngn t hoi

Nh bao che: hay phn cu trc bn trn (superstructure) c kch thc va phi, che chn cho mt ngi s dng. Nh bao che thng c din tch vo khong 1,0 - 1,6 m2/bn cu. Nh bao che gm khung nh, mi che, vch nh, ca ra vo. Vt liu s dng th rt a dng, ty theo kh nng ti chnh ca h gia nh hoc tp th, c th tn dng mi cy, l, g, gch , chung quanh chng ta. Kch thc mt khung bao nh v sinh c th tham kho sau (Hnh 2.10):


24


0,9 - 1,0 m

1,6 - 1,8 m

1,8 - 2,0 m

1,4 - 1,6 m 1,0 - 1,4 m

1,4 - 1,6 m

1,4 - 1,8 m

Hnh 2.10: Kch thc tham kho nh hnh khung nh v sinh nng thn Ty kh nng ca tng nng h, c th k ra cc loi vt liu nh sau: + Vt liu lm khung bao nh v sinh:: - Tre cy: cc loi tm vng, mnh tng, - Cy rng, cy vn cc loi: c, trm, bch n, gn, xoi, (nn chn cc cy gi bo m bn chc). - G rng lu nm nh: thao lao, du, - Gch xy, st ng, st hnh cc loi, ng nha PVC, - Ct c bton ct thp, cc , + Vt liu lm mi che, vch, ca, nh v sinh: - L da nc, l tranh, l da, rm r, - G cy cc loi - Tole trng km, tole fibro cement, - Gch th, gch ng, gch cement, - Vch nh v sinh c ni dng t st nho chung vi rm

v phn tru (t l theo th t: 3:1:1), trt ln khung bng tre v qut vi nu c th.

Hnh v sau gi cc hnh thc bao che cho nh v sinh (Hnh 2.11, a,b,c d v Hnh 2.12).


25



26

(Ngun: Peter Morgan, 1994)

Hnh 2.11.a: Nh v sinh bngkhung tre, p t bn, phn tre,mi l da nc.

Hnh 2.11.b: Nh v sinh bngkhung tre hoc cy, vch v mil da nc

Hnh 2.11.d: Nh v sinh vchxy gch nung, ca g, mi lpngi kiu m dng hoc tole xi-mng

Hnh 2.11.c: Nh v sinh bngkhung cy g, vch vn, mi lptole trng km hoc tole xi-mng


Kiu khung nh v sinh loi 2 ngn:

Hnh 2.12: Mt dng khung nh hnh cho nh v sinh 2 ngn

PHOTO: L ANH TUN

Hnh 2.13: Nh v sinh nng thn c xy bng gch, lp tn


27


B ngi (toilet seat): l ni ngi s dng nh v sinh ngi x b cht thi ca mnh. C 2 loi b ngi c bn l b ngi xm v b ngi bt. Loi b xm r tin v tng i v sinh hn loi b ngi bt nhng n c nhc im l d gy mi, t chn c bit l i vi ngi ln tui, yu khp, b chng tnh mch trng. B ngi xm thng phi dng nc di nu khng lm h thng x nc nh km. Loi b ngi bt ph bin cho cc h gia nh, loi ny thng km theo thng nc x b cht thi. B ngi thng lm bng xi-mng, snh s, g, B ngi thng c lm sn, bn ph bin cc ca hng vt liu xy dng hoc dng ni tht. L tiu nn c ng knh ti thiu 14 cm. Nng dn c th t xy dng b ngi theo hnh 2.14. (kch thc o bng cm):

+ Tm dale y bng b-tng ct thp Kch thc 1 m x 1 m, dy 10 - 15 cm + Bn chn xy bng gch th v xi-mng Kch thc 33 x 13 cm, cao 12 - 15 cm + Gia tm dale c khot l thot cht thi + Xy rnh thu cht thi c chiu dc dn vo l + Cn lng t xi-mng cht thi tri d dng

Hnh 2.14: Kiu b ngi xm n gin bng xi-mng

Trn th trng c nhiu kiu b ngi xm hoc ngi bt bng snh s gi khong 100 - 500 ngn ng, ty cht liu, hoc cao cp hn, c th ln vi triu/b bn cu. (Hnh 2.15 v 2.16).

27

22p xi mng

Bn chn 14 Tm dale

b-tng ct thp

Rnh thu cht thi

25

55

20

30

13

33

100

100

11


28


Hnh 2.15: B ngi bt (tri) v b ngi xm (phi)

Hnh 2.16: Bn cu bt v cc b phn chi tit

ng thng kh (Air vent pipe): l mt ng nh, thng bng PVC, c kch thc ng knh khong = 120 mm, cao hn 2,5 mt, thng trn tm mi che nh v sinh t nht l 0,5 m. Nu c iu kin ti chnh th


29


cng lm cao cng tt v n s gip cho s ht hi mnh, kh nng tn hi trn khng trung rng. ng thng kh ni vi h cha phn, dng thot kh cc kh hydrogen-sulfide (H2S), carbon-dioxite (CO2) v methane (CH4) trnh n mn ph hoi cu kin b tng ct thp ca b cha. u thot hi ca ng thng kh nn bc li ngn rui bay ngc t b cha phn ra u thot ca ng (Hnh 2.17). Nn chn li bng nhm hoc inox cng tt hn ch s n mn do cc kh trong h cha. h ca li ly t 1,2 - 1,5 mm, tui th ca li nhm khong 5 nm.

Hnh 2.16: Chi tit mt kiu ngn rui n gin ng thng kh

Co ch T

ng thng kh phng ln

Li ngn rui

ng thng kh

Mi nh v sinh

Kha nc (water closet): hoc cn gi theo dn gian l ci c ngng

hoc con th. Kha nc ch dng cho cc nh v sinh c dng nc (Chng 4). Kha nc l mt khc co hnh ch S nm ngang, nc thng thng gia 2 khc ngoc theo nguyn tc bnh thng nhau, mt thong ca nc cao hn mt lm trn ca kha nc (Hnh 2.12), kho nc c tc dng ngn cn cc hi hi thi t h cha i ngc vo nh v sinh. Kha nc phi lm bng vt liu kn, thng l snh s hoc nha c (Hnh 2.18 - 2.20).

Hnh 2.18: Hnh thc kha nc trong bn cu ngn mi hi


30


300

280

352

76

45165

115

115121 109

230

76

76

160

45

90

25

15

15

15

30 30 340

Hnh 2.19: Mt s kch thc tham kho cho kha nc n gin


31


Hnh 2.20: Mt kiu chu toilet d x vi co kho nc bng plastic ca n

(Ngun: http://www.toiletsforall.org/easyflush.html)

Mt bng

270

160

30

500 30 30

30

Mt bn Mt tm y

Hnh 2.21: Mt kiu bn cu bng plastic vi np y t ng m (Ngun: Uno Winblad, 1978)

Hnh v li, kch thc tnh bng milimt.


32


B t hoi (septic tank): hoc gi n gin l h cha hoc b cha, l b phn quan trng khng th thiu ca mt nh v sinh. B cha l ni tip nhn phn v nc tiu ca ngi s dng. B thng c hnh khi ch nht hoc hnh khi tr trn. B t hoi thng c thit k theo dng hnh trn bng cc cu kin lp ghp sn, mt s ni c xu hng xy theo hnh ch nht. B cha thng c xy bng gch th hoc c b-tng nh cc ng cng (hnh 2.21 v 2.22). ng b-tng thng c ng knh khong 1,00 - 1,20 m, cao khong 20 - 30 cm thi cng d, vn chuyn v lp ghp thun li.

Ni vng nng thn ngho th ch l mt h o su xung t, nn cht v c y bn trn bng cc tm dale b-tng, g vn hoc cy ghp. y b cha nn lm cao hn mc nc ngm ma ma v phi chc chn, khng sp l. Cn lu rng, b t hoi khc b lng ch l nc thi khng chy lin tc vo b t hoi nn tnh n nh thy lc khng ng dng c.

Hnh 2.22: H cha xy chm trong t nn cht

i vi b t hoi 2 ngn xy bng b-tng hoc gch th th chiu su nc trong b t hoi ly khong chng 1,2 - 2,0 m. Lu cn b tr tng chn gia cc ngn nhm gi li cc cht cn y v ngn cc vng bt ni pha trn mt nc (Hnh 2.24). Tm ngn ch T phi t ngp trong nc t nht 300 mm v nh ln khi mt nc 200 mm. Trn np b t hoi cn c np y nh ht cn (ht hm cu) thng k (khong 3 - 5 nm). Cc hm v sinh t hoi phi c ng thng kh.

ng thng hi

L thm

Mt t


33


Hn ghp bng va xi-mng

0,20 - 0,30 m

1,00 - 1,20 m

ng cng

Thanh

L thm

Hnh 2.23: H cha bng ng cng c b tng

ng ra bi thi

Mt t

ng vo b

ng thng kh

Np h bng inox hoc BTCTNp b cha

Ngn cha & t hoi Ngn lc Hnh 2.24: Mt ct ngang b t hoi 2 ngn

Ngoi ra, nhm cn cc cc cht kh trong b xm nhp vo cc ng ra ch T mang theo cc cht thi l lng (ng T cn c chc nng ngn khng cho vng


34


theo nc thi ra ngoi), ta c th thit k thm cc kt cu lm lch kh nh hnh 2.25.

Tm ngn vng bt ng ra T

ng ra T

Hnh 2.25: Cch t ng ch T v kt cu lm lch kh b cha

B t hoi cn c xc nh nh l mt cng trnh v sinh s dng lu di nn cn xem xt kt cu ca b cho chc chn. Lu :

Khng c s dng cc cht alkalis hoc cc cht ty ra nh thuc ty chlorine vo b t hoi. Nhng ha cht ny s hy hoi hoc lm chm cc tin trnh sinh hc trong b.

Trc khi s dng b, cn thit phi y nc n ng ra ca b. Nu c th, thm vo b mt t phn gia sc nh phn heo, b ang phn hy to iu kin cho cc vi khun trong b hot ng. iu ny lm cho b hot ng hiu qu trong nhng thi gian u.

Ngoi ra, mt s ch phm vi sinh cho b t hoi (c bn ngoi th trng) c th c s dng gia tng thi gian gia 2 ln ly cn.

Khng s dng nc c nng phn cao (pH < 4.0) hoc nc c nng mui ln (trn 0,4%) di ra cu v sinh.

Khng nn b cc loi rc thi rn, bng v sinh, vo b t hoi. Sau mt thi gian khong 3 - 5 nm, hoc nu c ng thm d bit cn khong 0,5 m th cc cht lng ng y b t hoi th cn phi ht loi ra ngoi. i vi vng nng thn, c th mc ln, trn vi cac cht hu c khc nh rm r, c mc ch cho hoai dng bn cy. Cc cc vng ven, th trn hoc th th thng thng, c nhng xe ht hm cu chuyn nghip vi cc bm ht, ng dn v thng cha ca cc Cng ty V sinh s m nhn cng vic ny, nh hnh 26, 27. ------------------------------------------------------------------------------------------------------- Chng 2: KIN THC C S V NH V SINH NNG THN

35


XE HT HM CU

Hnh 2.26: Xe ht hm cu

Hnh 2.27: Mt kiu xe ht hm cu nm 1880 ti Chu u

(Ngun: Witold Ryberynski et al., 1978)

Np y h cha phn: thng lm bng dale b-tng ct thp hoc ghp cy g. Np phi chc chn v kn, nu lm cy phi lu thay th, sa cha mi khi cy c du hiu h mc. Nu c th, nn chn cc cy ti sng (gn) hoc cc b tng. iu ny nhm bao m s an ton cho ngi s dng khng b lt ng xung h cha phn. i vi vng nng thn ngho, vng kh hn, c th lm np y h cha bng cy vn kt hp vi t st theo cch n gin 4 bc nh hnh 2.28. Cch ny n gin, r tin nhng khng kn hi, t st c th ri vo h cha, kh p dng cho h x dng nc m ch ph hp cho h x kh. Loi ny c thi gian s dng ngn v c th khng an ton cho ngi s dng nu khng sa cha thng xuyn. Trng hp c kinh ph v mun chc chn, lu di th nn lm np cha bng dale b-tng ct thp hoc phi hp b-tng v cy theo kiu lp ghp nh hnh 2.29. Nn c tm y l bng cy vn ngn rui vo h cha phn v mi hi t h cha phn bc ln.


36


Bc 4: Lp t st kn ming h o (ch cha l x)

Bc 3: y ming h o bng mt tm cy (vn) ghp

Bc 2: Lp t st kn quanh khung cy v ming h o

Bc 1: o h v Lp cc cy g cng trn ming h o

Hnh 2.28: Bn bc thc hin cch y h nh v sinh kiu n gin


37



38

Hnh 2.29 : Cch thc lp ghp np y nh v sinh in n g0,4 m

ng thot hi PVC 21 c bt li ngn rui u

p t st chung quanh tm y v cc

Tm y l 20 x 35 cm bng cy

Tm y 1,2 x 1,2 m bng tre an hoc, vn ghp, hoc BTCT Cha l 15 x 30 cm

0,6 m

0,4 m

0,4 m

1 m

1 m

H tr phn (o t ) (1 x 1 x 1,5) m

Thanh di 1,8 m bng cy hoc cc BTCT


2.5 CAO TRNH C BN CA MT NH V SINH Nh v sinh khi c xy dng cn lu v cao trnh. Mt s khuyn co cn thit mang tnh c bn:

V tr cao trnh trong khun vin nh nng thn th nn t sau nh nhng trnh ni qu thp, nc ng. Nu gp vng t thp th nn p cao nn nh v sinh. Ni ly t s to mt rnh thot nc chung quanh nh v sinh.

Nn nh v sinh nn cao hn mt t t nhin khong 20 cm. Mi nh v sinh chn chiu cao khong 1,80 - 2,00 m. y h cha phn nn phi cao hn mc nc ngm ma ma trong

iu kin cho php. Hnh 2.30 sau cho cao trnh tham kho mt kiu nh v sinh n gin.

-

200 Mi thng gi

B ngi xm

Nn nh x 20 Mt t

t nhin 0.00 Thnh bn (bng gch xy, g chng, ng cng b-tng, thng phuy hoc t st nn cht) Ct

300

120 Kch thc theo cm

Hnh 2.30: Cao trnh v kch thc tham kho cho mt nh v sinh n gin


39


2.6 XC NH THM CA T NN NH V SINH Mt nh v sinh c t nn ti xp hoc c thnh phn ht trong t ln c th l mt u th phn lng ca cht thi thm rt nhanh. Tuy nhin, khi thm qu ln m phn trong b t hoi cha kp phn hy th nguy c nhim t s ln, c bit l nhng ni c s hin din cao ca mc nc ngm. Do vy, vic xc nh tc thm rt ca t cng rt cn thit xem loi t nn ni d kin xy nh v sinh c ph hp hay khng. C nhiu cch xc nh thm ca t nn hoc din tch thm. Din tch thm cn thit c nh ngha l din tch b mt y thm nc v thnh ngoi nm trong t thm nc. thm nc ty thuc vo loi t v chiu cao p lc ct nc trong ging. Trng hp khng c iu kin kho nghim, c th ly vo khong 1 - 2 m2 din tch thm cho 1 ngi s dng. C th dng bng tra sau:

Bng 2.6: Din tch thm c ch (m2, cho 1 ngi) khi mun xy b thm Loi t

Loi nh (lt nc dng/ngy/ngi)

Nh (200)

Trm tri (100)

Trng hc (65)

Ct th hoc si Ct mn Ct pha st St trn nhiu ct hoc si St trn t ct hoc si St nng, t cng, khng thm nc,...

0,93 1,40 2,30 3,70 7,10

khng dng

0,23 0,37 0,60 0,93 1,85

khng dng

0,14 0,23 0,37 0,60 1,25

khng dng

(Ngun: J. Gruhler, 1980) Lm th nghim n gin sau (Hnh 2.31) xc nh thm ca t ngoi hin trng: ti ch t b, ni su y, o 1 h c kch thc hnh vung 30 x 30 cm, su 20 cm. y nc (lm t 3 - 5 ln), tnh trung bnh thi gian (pht) mc nc h xung 10 cm. Thm iu kin tt bn, lu lng thm:

2,6.5,2

1200+ tq s Thc o

trong : qs - lu lng thm (l/m2/ngy) t - thi gian (pht) cn thit mc nc h xung 10 cm V d: o t trung bnh = 2 pht => qs = 107 l/m2/ngy 30 x 30 20 cm

Hnh 2.31: H thc nghim Lu : Khi mi o ging khng nn o ngay m phi nc nhiu ln ri o th chnh xc hn.


40


NH V SINH NNG THN KHNG DNG NC

===============================================================

e 3.1 KHI QUT 3.1.1 nh ngha v u khuyt im Nh v sinh khng dng nc hoc h x kh (Waterless toilets/ Dry sanitation) c hiu l kiu nh v sinh m sau khi s dng ngi ta khng dng nc di ra, c th ch dng vi, tro bp, tro cy, tro tru hoc t bt ph ln phn sau khi s dng. Loi nh v sinh khng dng nc ny thng p dng cho cc vng nng thn gp kh khn ngun nc hoc p dng cho vng c tp qun s dng phn v nc tiu vi mc ch lm phn bn cho cy trng hoc dng phn ti nui c. Mt s ni, nh v sinh c thit k tch phn v nc tiu i theo cc ng dn khc nhau x l. hc cha phn, phn ngi c trn vi cc loi tro, t v c cc loi vi khun v nm phn hy trong iu kin hiu kh c s tham gia ca nhit , khng kh v m . Nh v sinh trn ao h hay cu c ph bin ng bng sng Cu Long c xem l nh v sinh khng dng nc mc du loi h x ny c lm vng t ngp nc thng xuyn. Hu ht cc loi nh v sinh khng dng nc u c mc tiu chnh l ly phn , c tn l h x phn hoc h x t hoi (Composting toilet) . Loi nh v sinh khng dng nc c nhng u v nhc im sau. u im:

R tin, chi ph xy dng rt thp. Loi ny thng n gin v d xy dng. Tit kim c nc. Khng phi tn cng dng nc di v ra sau khi s dng. C th s dng phn v nc tiu nh mt ngun cung cp phn bn hoc

nui c. Ph hp cho vng kh khn ngun nc, vng nng thn ngho. C th s dng cc vt liu a phng.

Nhc im:

Loi ny khng phi l cng trnh v sinh tt, c nhiu kh nng ly nhim v pht tn cc mm bnh cho cng ng.

t nhiu c mi hi v rui nhng. C nguy c gy nhim mi trng nc v mi trng t. Kh s dng lu di, tui th cng trnh ngn. Thiu tnh thm m. C th sp sn gy tai nn cho ngi s dng nu thiu cn thn.

3.1.2. phn compost Mt cch n gin, compost c nh ngha l mt cht hn hp t cc ch thi thc vt phn hy v cht thi ngi v gia sc, c th s dng bon vo t lm cho n ph nhiu hn.

----Cht ----------------------------------------------------------------------------------------------------- ng 3: NH V SINH NNG THN KHNG DNG NC

41


phn compost l mt bin php k thut nhm bin cc cht thi hu c d phn hy sinh hc nh phn ngi, phn gia sc, rm r, cy c, bn, rc thnh cht mn cha nhiu cht v c c th s dng trong nng nghip, thy sn v lm gim thiu s nhim mi trng. u im ca vic phn compost

Gim thiu nhim cho ngun nc, t v khng kh, cc cht hu c bin i thnh cc cht v c.

Dit cc mm bnh nguy him do trong qu trnh phn hy sinh hc, nhit trong hm gia tng, c khi ln n 60 C lm tiu hy cc trng, u trng, vi khun, virus trong cht thi. Phn sau khi c th c s dng an ton hn phn ti.

Phn sau khi compost tr thnh mt cht mn hu ch cho nng nghip nh tng ph nhiu ca t gip cy trng hp thu.

Tng m cn thit cho t trng, gim thiu s ra tri khong cht do cc thnh phn v c khng ha tan trong phn nh NO3- v PO43-.

Gim th tch do trong qu trnh phn, s mt hi nc gia tng do s gia tng nhit, iu ny khin m phn kh v ro nc hn. Phn c th tch nh hn s gip thun li trong vic vn chuyn, thu gom v ri.

Nhc im ca vic phn compost

Mc du phn ln vi khun, virus b tiu dit nhng khng phi hon ton, c bit khi s compost khng ng u v thi gian, phng php, lng , . Mt s mm bnh vn tn ti c th gy nguy him cho ngi s dng.

Thnh phn phn thng khng n nh v cht lng do thnh phn nguyn liu a vo khng ng u.

Phi tn thm cng v din tch. Vic phn thng dng th cng v l thin to s phn cm v m

quan v pht tn mi hi. Trong khi cc loi phn ha hc nh ur, NKP, gn nh, tng i r tin, cht lng ng u v "sch hn" gy tm l thun tin cho vic s dng hn phn compost.

3.2 CC KIU H X KH C CHUYN VN PHN 3.2.1 H x thng H x thng (the bucket latrine) l tn gi chung ch cch thu gom cht bi tit ngi qua thng, gi, x, b, ... ri em i ni khc (c hoc khng x l trc khi ni khc). H x thng c lm bng g, c np y. Ni thng l cc h o sn, cc vng nc hoc c lm phn bn. X thng sau khi s c khuy ra sch v ti s dng. y l cch ngi xa lm trc khi c h thng thot nc thi nh hin ny. Tuy vy, cch c in ny vn cn nhiu ni p dng nhiu ni trn th gii cc nc ang pht trin, khng ch cho tr con v ngi gi mi c p dng cch ny m c cho ngi ln (Hnh 3.1, Hnh 3.2). C l h x thng l dng r tin nht v c tnh c ng cao thu gom cht bi tit ngi. Trung hoa xa, loi h x thng rt ph bin, c p dng t cung vua quan n ngi dn d. H x thng thng lm bng g, hoc gm trng men, sau ny lm bng nha plastic. H x 2 ngn min Bc ph bin nhiu nm trc kia, cng l mt dng h x thng.

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Hnh 3.1: H x thng theo kiu Marino, 1858 ti Copenhagen (tri) vi thng ng phn v nc tiu ring bit nh s ha hnh (phi). Ngun: Witold Ryberynski et al., 1978

Hnh 3.2: "B xi" dng cho b chnh l mt dng h x thng (Ngun: trch t nh vui Art Unlimited Amsterdam) --------------------------------------------------------------------------------------------------------- Chng 3: NH V SINH NNG THN KHNG DNG NC

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3.2.2 H phn Bn trong Mt kiu Tu H phn Bn trong Mt kiu Tu (China Four in One composting) l mt cch thu gom phn s dng lm phn bn c s dng hng ngn nm nay Trung Hoa, c lc phng php ny c gii thiu min Bc Vit Nam trong nhiu nm trc y. Bn i tng thu gom y l: (1) cht bi tit ngi; (2) phn gia sc (heo, b); (3) t v (4) rc. Trong thp nin 50, khong 70% - 90% cht bi tit ngi c thu gom s dng lm phn bn v hng nm t c chng 300 triu tn (theo Dorozynski, 1975). n nay, khong 1/3 phn bn s dng Trung Hoa l t phn ngi v gia sc. cc vng nng thn Trung Hoa, nh vng Qung Chu, ngi ta d dng bt gp hnh nh nhng con heo c nui th di cc bi thu gom cht bi tit ngi nh minh ho m t Hnh 3.3. Phn c vn chuyn bng gnh hoc xe ba bnh. Theo ti liu ca Uno Winglad, lc phong tro tp th ha rm r nm 1956 ti Qung Chu, Trung quc, mi m c chng 15.000 x vin vng nng thn trn ln thnh ph thu gom phn ngi v em v lng. S ri vi trong qu trnh vn chuyn gy tnh trng mt v sinh trn ng ph. Theo tr gi phn bn Qung Chu nm 1975, gi ca t phn (nightsoil) vo khong 3,40 n 5,80 Nhn dn t ty theo thnh phn nc cha trong phn (Mc lng mt ngi bnh thng vo thi im ny khong 60 - 70 Nhn dn t mi thng).

Losphphv

---ChHnh 3.3: Minh ha mt h phn "4 trong 1" kiu Tu (Ngun: Uno Winglad, 1978)

i h phn ny tuy tn dng c phn, rc, nhng khng nn khuyn co dng v n khng c nh gi co v mt v sinh v thm m, mi hi t n, rc kh nng, vi khun, giun mc t phn c th sng k sinh trong heo. V ng din phn, lng m trong phn s b tht thot t nhiu do bay hi o khng kh (xem thm cch phn chng 5).

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3.2.3 H x phn 2 ngn kiu Vit Nam H x phn 2 ngn kiu Vit Nam (The Vietnamese double-vault composting latrine, gi tt l DVC) loi h x ny c B Y t ph bin trong mt chin dch rng ri t nm 1956 min Bc Vit Nam. Loi h x 2 ngn c thit k phn v nc tiu thu gom ring r. Loi ny uc xem l loi h x kh, ym kh, khng dng nc hon ton (Hnh 3.4, Hnh 3.5).

Hnh 3.4: H x 2 ngn kiu Vit Nam (Hnh ct phi cnh, tri), Hnh 3.5: H xi kiu ny c p dng Mexico (phi)

(Ngun: http://www.weblife.org/humanure v http://www.ias.unu.edu/proceedings/icibs/ecosan/clark.html)

Din tch thng thng cho mt nh v sinh loi ny khong 1,8 2,0 m2, c xy bng gch nung th, xy theo kiu hc cao chng 0,8 m, c vch ngn thnh 2 hc lin k vi nhau, mi hc c dung tch khong 0,3 m3. Ngi s dng c th tham kho kch thc hc cha phn bng 3.1. Pha trn np hc (xy bng dale b-tng) b tr 2 b ngi xm i xng vi nhau. Phn c x trc tip vo hc. L nhn phn c y bng mt ci np y c cn di. Gia 2 b xm l mt rng dn nc tiu thot ra ngoi v gom vo mt cc chu hoc b snh. mi hc c tm ca g ng m hc cha phn. Nn hc c th xy bng gch, b-tng hoc t nn. Hc c xy cao t nht khi mt t l 10 cm ngn nc ngp hoc nc ma trn vo bn trong hc. Nh v sinh c xy xa ni ch hoc ngun nc ti thiu 10 mt. Loi h x 2 ngn ny cng c che chn bng cc vt liu xy dng a phng nh tre, cy, tranh, l, ... Trc khi gom cht bi tit, nn hc c ri bng mt lp t bt, vi bt hoc tro cy nhm rt nc phn v ngn vic thm t nc ngp, hn ch mi v rui nhng. Sau mi ln s dng, ngi ta ph ln phn mt lp tro hoc t bt (Hnh 3.6).


45


Bng 3.1: Kch thc chn la cho h x 2 ngn Qui m gia nh

Chu k ly phn

4 - 7 ngi Rng x Di x Su

(kch thc bng m)

8 - 12 ngi Rng x Di x Su

(kch thc bng m)

4 thng

6 thng

12 thng

2.4 x 1.0 x 0.6 2.2 x 1.0 x 0.7 1.8 x 1.0 x 0.8

2.6 x 1.2 x 0.7 2.2 x 1.2 x 0.8 1.8 x 1.2 x 1.0

2.6 x 1.4 x 0.8 2.2 x 1.4 x 1.0 2.0 x 1.2 x 1.2

2.8 x 1.0 x 1.0 2.0 x 1.2 x 1.2 2.2 x 1.2 x 1.1

3.0 x 1.2 x 1.2 2.6 x 1.3 x 1.3 2.2 x 1.4 x 1.4

3.0 x 1.4 x 1.4 3.0 x 1.3 x 1.5 2.8 x 1.3 x 1.6

(Ngun: ENSIC, Bangkok, 1987)

0,9 - 1,0 m

Ca ly phn(0,25 x 0,3 m)

X nc tiu

Sn dc thu

nc tiu

Hc ang s dng

Tro cy Phn Tru

Ct dy 0.3 m Sn si 0.2 m

Np y Hc y y np

Ch phn hoai

ng thng hi

Mi h x

0,7 - 0,8 m

0,9 - 1,0 m

1,80 - 2,0 m

Hnh 3.6: Kt cu h x 2 ngn kiu Vit Nam


46


Mi h x 2 ngn ny c 5 10 ngi s dng, ngi ta s dng mt bn ca h x 2 ngn, pha bn kia y kn. Khi pha bn ny y, khong sau 2 thng th s dng hoc bn kia v phn c co rt ra khi bn ny. Theo B Y t nc Vit Nam Dn ch Cng ha (1968), nhit bn trong hc cao hn nhit bn ngoi khong 2 6 C, ring v ma h, khi nhit bn ngoi l 28 32 C th nhit bn trong hc phn c th t n 50 C. ngn cn trng pht trin, chung quanh h x ny ngi ta thng trng cy s (Citronella) v cy Acilepsis squaros. Theo cc vin chc ca B Y t sau 45 ngy phn c y kn trong hc tt c cc vi khun v virus trc khun, trng, u trng v k sinh trng ng rut u b tiu dit v cc cht hu c c hi tr thnh khong cht (trch dn bi McMicheal, 1976). Theo mt bo co ca B Y t, 1978, phn ngi sau khi c nh vy tr nn khng cn mi hi v c s dng nh mt loi phn bn rt tt. Loi phn ny khi dng bn rung gia tng nng sut cy trng t 10 25% nu so snh vi phn ti (khng c cho hoai). Theo Witold Ryberynski et al., (1978), loi h x 2 ngn ny c gii thiu trong cun sch Health in the Third World in nm 1976 v c tc gi l b Dr. Joan McMicheal, nh gi cao v mt v sinh mi trng cho cc nc ang pht trin. Kiu h x 2 ngn ca Vit Nam c gii thiu v p dng cho mt s quc gia vng Trung M nh Mexico, Guatemala, vi mt s ci tin nh.

Hnh 3.7: Hnh phi cnh h x 2 ngn kiu Vit Nam (Ngun: Witold Ryberynski et al., 1978)


47


Tng t nh H x 2 ngn kiu Vit Nam, cc nc khc cng c hnh thc p dng tng t nh hnh sau: 3.2.4 H x t hoi do ch nh t xy (Owner-built composting toilet) Loi ny l mt kiu nh v sinh n gin c ph bin rng ri nhiu vng nng thn trn th gii, do ch nh t xy v h khng c kh nng ti chnh trang b mt nh v sinh tt lm sn, c bn trn th trng. Nng dn li dng kh nng phn hy phn ngi t nhin ngay trong iu kin nhit thp. u im ca loi h x ny l r tin m vn c th bo m mt kh nng x l phn ngi tng i v sinh v an ton, gn nh khng dng nc hoc dng rt t, qun l n gin v t hao nng lng, vn hnh khng mi hi v phn ngi c ti s dng cho nng nghip. Kt cu kiu h x ny nh hnh 3.8, mi v vch c th lm bng bt k vt liu no kim c, ch c sn nh th lm bng b-tng nh, nh x cng c 2 hc ring bit, khi s dng y hc ny s c ng kn, ri sang hc kia v ch cho hc y phn t phn hy. Mi hc c gn 2 ng thng hi t lch v tr nhau, gia 2 ng l mt vch ngn t cho nh hnh 3.4 ngn cn mi hi ta n ngi s dng. Mi bn hc c th s dng khong 1 - 2 nm. Phn v nc tiu ngi thi xung c lp bng cc cht hu c giu carbon t thc vt, d phn hy nh mc ca, i khi l l cy, bo, c,

Hnh 3.8: H x t hoi kiu ch nh t xy (hnh ct phi cnh)

(Ngun: http://www.weblife.org/humanure)

3.2.5 H x t hoi kiu Guatemalan (Guatemalan composting toilet) Loi ny l mt kiu bin th kiu ca Vit Nam, h x ny tch ring phn v nc tiu. Nc tiu c thu gom qua mt vch ngn b ngi, c ng dn i ring v b tiu nh hnh 3.9 v c dn ra ngoi cha trong mt bnh bng snh. Nc tiu tch ring do mau hoai hn, cha lng m cao hn v hn


48


ch c tnh trng t v khai thi khi ha chung vi phn ngi. B ngi c th di chuyn c ch khng c nh nh kiu Vit Nam.

Hnh 3.9: H x t hoi kiu Guatemalan

(Ngun: http://www.weblife.org/humanure) 3.2.6 Nh x t hoi c ng dn (Batch composting toilets): Kiu ny cn c tn gi l Nh x Multrum (do mt k s ngi Thy in thit k, ng Clivus Multrum - c l Clee-vus Mul-trum) (Hnh 3.10 v 3.11). Theo Multrum, mt ngi bnh thng s thi ra 40 kg phn mi nm, nu s dng nc di th s lm nhim khong 25.000 lt nc hng nm, do vy ng thit k ra loi toilet ny nhm tit kim nc v s c phn hoai ti s dng cho bn cy. Nh x loi ny c xy dng M t nm 1964. Theo thit k nh x Multrum, phn v nc tiu cng thu gom vo mt hc cha 2 y. Hm dn v cha phn c lm kn, dng mng nghing c kch thc mt ct khong 1 x 1 m2, di chng 3 m. Phn hoai sau hn 1 nm s c ly ra qua mt ca hc . Nhit trong hc va mt, khng nn qu 32C. Phn sau khi s c chn di t hoc bn cho cc vn cy cnh. Theo mt bo co nm 1977 ca Clivus Multrum ti M v kt qu phn tch dinh dng ca phn t 7 nh x Multrum sau khi c s dng t 4 n 14 nm. Phn c trung bnh 58% cht hu c, trong 2,4% l nitrogen, 3,6 % l phosphorous v 3,9% potassium. Thnh phn ny cao hn cc loi phn t cc cht b ng cng thot nc, hoc phn rc hoc phn xanh. tp trung dinh dng phn nh x cng c ghi nhn. Cc c cht kim loi tm thy phn loi ny cng thp hn mc an ton cho php. Nu nh x Multrum c qun l tt th khng c mi hi. iu ny cng khch l cho nhng ai c mun s dng nh x t hoi loi ny nhm hn ch vic nhim phn cho ngun nc, nht l ngun nc ung. Kiu nh x Multrum vi cc thay i cho r tin hn cng c gii thiu Philippines, Agrentina, Botsawana v Tanzania nhng, rt tic khng thnh cng. Theo tng thut ca Winblad (1998) th "Cc nh m ti n xem Phi Chu th h c mi hi kh chu. Rc ri l vic trn


49


cc cht bi tit vi cc loi thc vt th qu t v trong ma kh khng c cy l trn chung vi phn ngi". C l mt phn do qun l km v cha hiu c ch phn hy nn vic p dng cn hn ch cc ni ny: C qu nhiu cht lng trong phn s to ra iu kin ym kh vi vic to ra mi hi.

H(Ngu

------------------------Chng 3: NH V Hnh 3.10: H x kiu Multrum

(Ngun: http://www.weblife.org/humanure)

nh 3.11: Mt kiu h x Clivus Minimus ci tin n: http://www.yourhome.gov.au/technical/fs23.htm )

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Hnh 3.12: K s Clivus Multrum vi kiu h x do ng thit k

i Ta nh i hc Slippery Rock, M (Source:

3.2.7 H x ly phn Loi ny c ktphn di y ch ngnc tiu cng xuli, cn nc tiu v ngoi bng mt ng d

(Ngun: h

------------------------------Chng 3: NH V SINt

The Humanure Handbook. Jenkins Publishing)

bng xe (Wheelie-batch Composting Toilet): cu bn trn cng nh cc loi trnh by trn, ch c i l mt xe y c 2 bnh nh hnh 3.13. Loi ny phn v ng xe y, y thng xe l 1 li lc phn trn gi phn nc dch t phn thm chy xung di v c rt ra n. Khi xe y th thay bng mt xe mi.

Hnh 3.13: H x ly phn bng xe ttp://www.yourhome.gov.au/technical/fs23.htm )

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3.2.8 Nh v sinh kiu trng quay in hnh loi l nh v sinh t hoi kiu Carousel (Carousel style composting toilet) (Hnh 3.14), ph bin nhiu ni vng nng thn Bc u. Thay v ch c 2 h cha phn lun phin, Carousel thit k 4 ngn cha hnh trn, c tay gt xoay 90 cho mi khi ngn cha y phn. Trng quay c quay bng tay trn cc thnh phn trong phn, gm cht bi tit v cc vt cht cha carbon nh ru than bn. i khi, trong ma ng lnh, ngi ta c trang b thm in si nng phn hoc thm t nc m. Phn c ly ra ngoi t mt np di trng quay. Phn hoai dng bn cy trng. Nguyn tc phn cng nh cc loi trn.

Hnh 3.14: Nh v sinh t hoi kiu Carousel (Ngun: Ecological Sanitation, 1998)

3.2.9 Nh v sinh dng mt tri Nh v sinh dng mt tri (Solar toilet) (Hnh 3.15) c thit k vi ngn cha phn c th phi ra nh nng mt tri vi tm gng trong sut bn trn v khung cha phn c lm bng st khng r. Nng lng t mt tri s cung cp nhit h phn m ln to iu kin cho phn d phn hy. Loi nh v sinh ny cng nhn phn v nc tiu gom chung v khng s dng nc di ra. Nguyn tc phn cng nh cc loi trn.


52


Hnh 3.15: Nh v sinh Mt tri

(Ngun: Ecological Sanitation, 1998)

3.3 CC KIU NH X KH KHNG C CHUYN VN PHN 3.3.1 Nh x trn sng h hay cu tm Nh x trn sng h (the overhung latrine) hoc cu c hoc cu tm l mt loi cu quen thuc nhiu vng nng thn v vng ven th, c bit l cc ni c sng nc nh ng bng sng Cu Long (Hnh 3.16). Mt du loi ny c xy dng trn ao h nhng cng c tm xem l h x kh v chng ta khng dng nc di ra sau khi i v sinh. Loi cu v sinh ny c xy dng mt cch n gin sau hng nh m pha di l cc bi sng ngp theo thy triu hoc pha sau cc ghe xung ca cc h gia nh sng trn sng rch, hoc dng mt nh tiu dng trn cc, pha di l ao h, hoc bi bin. Phn thi ra c dng nc theo thy triu hoc dng chy trn sng em i hoc pha long. y l loi h x c nh gi thp v mt v sinh v m quan. Nhiu ni, ngi dn nng thn xem vic s dng phn thi nui c (c v, c tr, c tr phi, ...) nh mt ngun thu nhp ph. Cht thi t cu tiu trn sng rch l ngun nguy c pht tn bnh dch v gy nhim ngun nc mt cch c bit. Theo cc c quan v sinh phng dch, nhng vng qu c nhiu cu tiu trn sng thng l nhng ni xy ra dch bnh lin quan n ngun nc nhiu nht v ngun nc nhng ni ny c dng cho vic n ung, tm ra v git gi o qun. Hnh 3.17 l mt xut ci tin h x trn ao nhm c mt cch bo v ngun nc t b nhim hn.


53


PHOTO: L ANH TUN

Hnh 3.16: Cu c ph bin ng bng sng Cu Long

Li

Nn t khng thm

ng x t ti ct ra sng

Ct

Sy Van 1 chiu

ng ly nc t sng

ng x t aoSng

Ao c

Nh x

on x l nc qua ct v sy

Hnh 3.17: xut kiu nh x trn ao c ci tin gim nguy c gy nhim ngun nc t nh x trn ao c, dc theo chiu di (hoc chiu rng) ca ao ni on tip gip vi ngun nc ta o mt on rnh di v ct vo rnh (loi ct "-mi") thnh mt di ct (hoc ti ct), on ny cng di v rng th cng tt, nn c gng trn 2 - 3 mt. Pha trn on ct ta lp t st tht v trng sy trn vi mt t nht khong 25 cy/m2 (hoc c Vetiver: loi c ny c kh nng chng xi l cao). Ni 2 on ng x t ao ra sng, ng tip gip vi ao t y di ct, on ng t di ct ra sng t u trn ca di ct. y l kiu lc nc bn qua t cng bc khi mc nc trong ao cao hn mc nc sng. ng ly nc t sng vo ao th t cao hn di ct v on ng pha ao c b tr van 1 chiu nhm ch cho nc t sng vo ao m khng c chiu chy ngc li.


54


3.3.2 H x cn H x cn (the feuille) ch l mt h o nng xung mt t khong na mt, pha trn c y s bng cy g, sn tre, i khi n gin ch l 2 lng cy bt song song... (Hnh 3.17). Chung quanh h c che chn s si. Loi h x ny thng c cc vng nng thn xa, vng ni, vng khan him ngun nc. Sau mi ln i thi, ngi ta ph nh ln phn mt lp t. Sau mt thi gian, khong vi tun n 1-2 thng th h y, ngi ta lp kn bng t v che y bng mt tm chn bt k no h kim c nh mt tm nylon, mt tm phn hoc mt v st ph thi ch mo v cc ng vt khc khng o bi v ngi khc lu trnh trng o ch ny. Loi h x cn ny, thot tin c v v sinh hn loi cu tiu trn sng nhng tht s cng l ngun gy nhim t v nhim bnh t cc loi rui nhng v giun mc tn ti rt lu trong t. H x cn ch nn s dng trong cc trng hp khn cp v tm thi cho vic bi tit. Lu : Cn thn i vi cy trn ming h, trong iu kin ny, cy rt d b mc v gy, c th gy nguy him cho ngi s dng !!!

Phn t y (c khung )

Phn khung bao che

Phn h o cn

Hnh 3.17: Cc phn "lp ghp" ca mt h x cn


55


3.3.3 H x o chm H x o chm (The pit latrine) cng l mt dng h o di t nhng su hn h x cn, p dng cho cc vng t cao, thm nc tt, thng

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