Tim nng ng dng cng ngh x l phn bn b t hoi cho cc th Vit Nam

Tim nng ng dng cng ngh x l phn bn b t hoi cho cc th Vit Nam

I. M u

Thut ng Phn bn c nh ngha l hn hp bn, phn v cht lng thu gom c t h thng v sinh ti ch, ring l nh: cc nh x, nh v sinh cng cng khng c cng thot nc, b t hoi v h x di nc.

Phn bn b t hoi l phn bn to ra t cc b t hoi (cn lng, vng ni hoc dng lng). Qu trnh hnh thnh phn bn c din ra ch yu trong cc b t hoi. B t hoi tip nhn cc sn phm bi tit ca ngi t cc cng trnh v sinh, x l phn cht lng bng cch lng cht rn. Phn cht rn trong bn cn l 660 g/kg, t trng in hnh ca cn lng y dng bn l 1,4 1,5 t/m3 (gn ging cn lng nc thi) v hm lng nc ( m) l 50%.

Khc vi nc thi, tnh cht ca phn bn tu thuc vo thi gian lu trong b t hoi. Thnh phn hu c ca cc loi phn bn t cc cng trnh v sinh c thi gian s dng khc nhau c trnh by Bng 1. Cc thnh phn ny nu c x l v thu hi theo phng thc hp l s l ngun phn bn thc s c ch cho cy trng v ng thi gp phn lm gim nh ti trng ca h thng ng ng thot nc ti cc th v gim nguy c gy nhim mi trng.

Bng 1: Thnh phn hu c ca phn bn t cc cng trnh v sinh khc nhau

Loi bn/cnCht hu cNit tng sPhot pho tng s Nit tng s Nit tng s Nit tng Phot Pht pho tng s

Phn bn t cc b t hoi h gia nh (sau mt n ba nm s dng)71 812,4 3,02,7 2,9

Phn bn t cc b t hoi h gia nh (sau nhiu nm s dng) 30,40,970,71

Phn t khu v sinh trn my bay (phn ti)85 - 88

3,2 3,72,6 2,8

Trong khun kh ca d n hp tc v Tng cng nng lc gio dc, o to v nghin cu trong lnh vc khoa hc v cng ngh mi trng min Bc Vit Nam, Phng Cht thi rn, Trung tm K thut mi trng th v khu cng nghip (CEE-TIA), nay l Vin Khoa hc & K thut mi trng (IESE), trng i hc Xy dng nhn c s h tr k thut t cc chuyn gia EAWAG.SANDEC Thu S nghin cu cc phng n cng ngh x l phn bn ph hp vi iu kin Vit Nam. Bi bo ny gp phn qung b tim nng ng dng cng ngh x l phn bn ph hp vi iu kin pht trin cc th Vit Nam

II. Cng ngh x l phn bn chi ph thp

X l phn bn chi ph thp bt u c th nghim p dng Vit Nam trong qu trnh thc hin d n, cc chuyn gia EAWAG.SANDEC Thy S cng nhm nghin cu phn bn (FSM) ca i hc Xy dng hp tc tch cc vi Cng ty Mi trng th Nam nh, H Ni, Nng v Hi Phng vi cng ngh chnh l s dng kh nng ng ho cht dinh dng ca cy trng trong cc ngn lc (bi lc c trng cy). Kt qu nghin cu cho thy bi lc ngm trng cy vi dng chy ng p dng vo x l phn bn trong iu kin Vit Nam cho hiu qu gim nit t 25 - 32% v pht pho t 18 - 22%. Nhiu loi cy trng phong ph, sn c Vit Nam c th s dng trong x l phn bn nh cy ci (Scirpus triangulatus), cy dong ring (Canna); cy sy (Pragmites communis) vi cc ti trng khc nhau tu vo tng iu kin c th ca a phng.

Th nghim p dng cng ngh kh nc v n nh sinh ho trong cc khoang lc c trng cy khi x l phn bn thnh ph Nam nh. Trong iu kin thng ht v thu gom khng thng xuyn phn bn t cc b t hoi, ti trng np vo cng trnh lc c trng cy thp, phn bn c khi lng t s cho hiu sut kh cc hp cht hu c ln ti 93%, hiu qu kh vi trng gy bnh trn 90% v cht lng c th x ra sau khi x l trong cc h n nh. Cc b lc c trng cy c la chn l phng n c ph hp ti Nam nh sau cc nh gi chi tit v tt c cc cng ngh x l cht thi t b t hoi sn c ti thnh ph ny (Bng 2).Bng 2. Mt s kt qu nghin cu ti trm x l phn bn ti Nam nh, Vit NamTnh cht ca phn bn t b t hoi hot ngKhong gi trGi tr trung bnhHiu qu x l

pH7,41 - 7,467.5

TS (mg/l)17.410 - 40.00018.70095 - 97%

TVS (mg/l)4.570 - 25.0701.470

SS (mg/l)980 - 1.7401.160

TCOD (mg/l)20.400 - 79.09013.25041 93%

TKN (mg/l)1.260 - 1.78092010 - 29%

T - P (m/l)570 - 2.76061510 - 22%

Trng giun (S trng/g TS)85 - 12090

(Ghi ch: Cc s liu trong bng l gi tr trung bnh ca 72 mu trong nm 2005)

Cng ngh x l phi trn phn bn vi rc thi hu c qui m cng nghip c xut p dng ti Hi Phng - Vit Nam. Theo cng ngh ny, cc cht dinh dng cho cy trng nng nghip nh nit, pht pho c thu hi di dng sn phm phn hu c vi ngun nguyn liu u vo l rc thi hu c v phn bn b t hoi. III. X l v ti ch phn bn cng ngh cao

H thng x l v ti ch phn bn cng ngh cao (H thng SAN Tre-Cycling) ang c p dng ti Nht Bn l h thng tng hp c th x l cc loi bn hu c t trng cao bao gm: Phn ti t cc cng trnh v sinh, bn Jokaso, bn b t hoi, bn cng, bn thc n cng nghip, rc nh bp v ph thi ng vt.

Trm x l ca h thng San Tre-Cycling c th x l bn thu gom, phn bc ti, ph thi t thc phm, v ph thi ng vt.

Nguyn tc hot ng: H thng x l phn bn c t cch xa ni pht sinh gm cc cng on ch yu sau:

- Thng ht phn bn t cc cng trnh v sinh;

- Vn chuyn phn bn bng xe tc chuyn dng n trm x l;

- Phn bn c bm vo cc b cha v x l theo phng php hin i theo 2 hng: + Nhng cht thi khng s dng c s c phn loi v c a qua h thng b x l sinh hc m bo cc tiu chun v sinh.

+ Nhng cht thi c cha nhiu cht hu c s c tch ra v c trn vi rc hu c c nghin v phn loi. Hn hp ny c a vo b mtan, kh sinh hc c s dng lm nng lng cho my pht in. Cn cn li tip tc c x l hiu kh trong b phi kh c bn hot tnh. Bn sau khi tch nc, x l phi trn vi rc thi hu c ch bin phn compost.

u im ca h thng: H thng SAN Tre-Cycling c th ci thin ng k iu kin v sinh mt cch hiu qu v chi ph, c bit nhng ni cha pht trin h thng cng thot nc ng b.

Khi pht trin h thng thot nc, trm x l ca h thng SAN Tre-Cycling s c s dng x l bn thi t cc trm x l nc thi v phn bn t cc cng trnh v sinh ti ch khu vc khng thuc phm vi phc v ca h thng cng thot nc.

Cc u im ca cng ngh kh nit nng cao bng mng:

- C th loi b BOD9, SS, COD, Tng N, Tng P v kh mu thng qua qu trnh kh nit/nitrat ho dng mng v x l cng ngh cao bao gm ng t v hp th bng than hot tnh.

- Mng c th gi cho hn hp gm cht lng v cht rn l lng c nng cao trong cc b phn ng sinh hc trng thi ph hp nht.

- Mng c th phn tch nc x l v bn, do khng cn phi lin tc theo di

- Khng i hi pha long v do tit kim khng gian lp t v chi ph bo tr.

- Cht lng nc tch ra t x l phn bn c trnh by Bng 3.

Mt iu cn c nhn mnh l vic la chn cng ngh x l phn bn phi m bo yu cu p dng nhng cng ngh c hiu sut x l cao ng thi phi tnh n hiu qu chi ph v p ng cc yu cu bo v iu kin v sinh v mi trng. Bng 3. Cht lng nc qua x l bng mngNng cht hu c c trong phn bn b t hoi (mg/l)Phn tch bng mng. X l sinh hc th nhtPhn tch bng mng. X l sinh hc th hai v kt ngNc thiTng tiu hu (%)

Nng Loi b (%)Nng Loi b (%)Nng Loi b (%)

BOD13.6002099,9105010099,93

COD cr30.0001.60094,770056,31008699,97

SS12.0002099,85755099,96

Tng N4.0003099,32033,320099,5

Tng P80040050598,85099,38

IV. Kt lun

hu ht cc th Vit Nam, phn bn b t hoi sau khi c thng ht thng c thng ra bi chn lp cng vi cc loi rc thi th, hoc x trc tip vo cc h nui c, hoc s dng trc tip bn cho cc loi rau qu. iu ny khng nhng gy nhim mi trng m cn l nguy c tc ng trc tip ti sc kho cng ng. Tuy nhin trong nhng nm gn y, vn nghin cu cng ngh x l loi cht thi ny v ang bt c s quan tm. Trong khun kh cc d n ODA nc ngoi, cng ngh x l phn bn bc u c p dng m in hnh l cng trnh x l phn bn Hi Phng, Nam nh, H Ni, Tp H Ch Minh v Nng. Trong khun kh ca d n Tng cng nng lc nghin cu khoa hc v cng ngh mi trng min Bc Vit Nam (ESTVN) do SDC ti tr, Trng i hc Xy dng phi hp vi cc Cng ty Mi trng th H Ni, Nam nh, Hi Phng tin hnh nhng nghin cu khoa hc v cng ngh x l phn bn b pht ph hp vi iu kin Vit Nam. Hy vng nhng kt qu nghin cu s gip cho cng tc x l phn bn b pht Vit Nam c hiu qu gp phn bo v mi trng th ngy cng hu hiu.

Ngun: Bo co ca Vin KHKT Mi trng - H Xy dng HN ti Hi tho "Cng ngh x l cht thi th v khu cng nghip", thng 4/2009