TAP CHi KHOA HQC DAI HOC VAN LANG Tran Thj M5 Digu va tgk

DAIVH GIA KHA NANG TAI SU' DUNG BUN KY KHI TlT HE THONG XU" LY KY KHI U ' 6 T HAI GIAI DOAN CHAT THAI NONG SAN

REVIEW THE CAPACITY OF ANAEROBIC SLUDGE RECYCLE FROM WET

TWO-PHASE ANAEROBIC TREA TMENT SYSTEM FOR A GRICUL TURAL

WASTES

TRAN TH/ Mf Dl£lf\ HUYNH TAN L 0"^ va LE THI KIM OANH^'"^

TOM TAT: Nghien ciru dd chung minh rdng biin sau phdn huy ky khi irdt 2 giai doan, chdt

thdi ndng sdn tkuc pkdm cd khd ndng tdi su dung true tiep nhu mot dgng compost long de

bd tra cho ddt trong do trong thdnh phdn cua logi biin ndy khong chira chdt doc hgi nhu:

thudc trie sdu, kim logi ndng vd vi sinh vdt gdy benh. Tdng hdm luang nita trong bun ky khi

dao dong trong khodng 3,2 - 6,0% (tinh theo khoi luang khd) vd tdng ddn theo thdi gian

van hdnh he thdng phdn hiiy ky khi udt, trong do N-NH/ chiem khodng 14,6 - 20,4%

(tucmg img vdi khodng 0,6 - 1,1% tinh theo khdi lirang kho). Thdnh phdn phospho sdn cd

trong biin chi d muc 0,72 - 1,2%, trung binh 0,92% nen de dgt tieu chuan phdn hihi ca

sinh hoc (theo TCVN 7185:2002) cdn phdi bd sung them P. Bdng cdch thdi khi cd the logi

bd miii hdi tit bun sau 2 ngdy vd bun dgt trgng thdi on dinh sau 8 ngdy. Neu ly tdm tdeh

nuac, phdn chdt rdn thu duac cd hdm lu(mg chat kho dgt 73,5% vd VS cua thdnh phdn

bdng 70% tinh theo khdi luang khd. Trong khi dd, phdn nude tdch ra cd ndng do COD len

den 1600 mg/L cdn xir ly trudc khi xd thdi vdo ngudn tiep nkdn.

Tu khoa: chdt thdi ndng sdn; qua trinh phdn huy ky khi u&t; biin ky khi; biogas; compost.

ABSTRACT: The research shows that digested sludge of two-stage wet anaerobic

digestion system from agro-waste can be reused directly as liquid compost to be soil

amendment due to no poison in this sludge such as: pesticides, heavy metals and

pathogens. Total nitrogen in digested sludge is in range of 3.2 — 6.0% (dry weight) and

increased follow the operation time, while N-NH4" accounts for 14.6 - 20.4% (correspond

to 0.6— 1.1% in dry weight). The available phosphate composition in sludge is only in 0.72

- 1.2% the average is 0.92% so it needs to be added phosphate to be bio-organic fertilizer

(TCVN 7185:2002). The aeration can be applied to remove the odor after 2 days and get

tke stable condition within 8 days. The TS, VS of collected solid part by centrifuge is

73.5% and 70% (dry weight), respectively. While, COD of the remaining water is 1600

mg/L and it must be treated before discharging to the reception source.

Key words: agro-wastes, wet anaerobic digestion; digested sludge; biogas; compost.

**' PGS TS. Trucmg Dai hpc V5n Lang, Email: tranthimydieii@vanlangum.edu.vn *"'ThS. Tmang Dai hgc V5n Lang, £maj7 huynhlan!oi@vanlangum.edu.vn (•••) GVC.TS Trudng Dai hoc Van Lang, Email: lelhikimoanh@vanlangum.edu vn

TAP CHl KHOA HQC DAI HOC VAN LANG So 01/2017

I. DAT VAN DE Qua trinh phan hiiy ky khi dugc ap

dung dl xii ly chdt thai tir giiia nbu'ng ndm 1800 va trd nen kba pb6 biSn trong nhihig nam gdn day nhd kba nang tao ra nang lugng tir chdt thdi [5, tr. 701 714]. Tiiy theo bam lugng chdt ran trong h6n hgp u, qua trinh phan huy ky khi dugc phan loai thanh; phan hiiy ky khi udt vdi ham lugng chdt rdn dao dong trong khoang 4 - 8% va phan hiiy ky khi kho khi ham lugng chat rdn tir 22% trd len [10]. Hieu qua thu hoi khi sinh hpc ciia qua trinh phan hiiy ky khi udt da dugc chimg minh qua nhieu cong trinh nghien ciru va irng dung thuc te nhd tinh dan gian trong viec tao dieu kien xao tron, tang kha nang tiep xuc va dong nhat ciia hon hgp ii ky khi. Tuy nhien, mgt trong nhimg nhugc diem ciia cdc be thong phan hiiy ky khi udt la su hinh thanh mgt lugng Idn bdn hgp "bun" sau khi phan hiiy d dang long vdi ham lugng chat ran thap gay kbo khan trong viec xii ly triet de cung nhu tai sir dung va tang chi phi van chuyen so vdi trudng hgp phan hiiy ky khi kho. Mac dii, theo Zeshan vd Visvanathan [12, tr. 167 -175], vdi dde tinh ciia biin con lai sau qud trinh pban biiy ky khi, loai biin nay c6 the sii dung true tiep lam chat bo trg cho ddt trong hoac phai xii ly bang qua trinh hieu khi trudc khi bdn cho dat trong nhirng thuc te cho thay, hau het bun sinh ra tir qua trinh phan hiiy ky khi (ggi tat la bun ky khi) deu khong the sir dung ngay lap tire lam chit bd trg cho ddt trong vi con phu thugc vao timg giai doan phat trien ciia cay trong, loai dat va muc do on dinh ciia biin va do do, bun nay can luu giir hay on djnh them vai thang trudc khi sir dung [9, li. 7041 - 7050]. Hon

niia, trong nhilu trudng hgp loai biin nay can dugc tach nude de tao dieu kien thuan lgi cho qua trinh xu ly va van chuyen [1, tr.56 - 63], [11, tr. 840 - 845]. Phdn nude tach ra co the sir dung trv:c tiep lam phan bon trong nong nghiep [4, tr.30 - 36], tuan hoan lai he thong phan buy ky khi de hieu chinh do dm cung nhu bo sung nguon vi sinh vat ddi vdi b6n hgp chat thai mdi dua vao he thdng [6, tr. 821 - 826], dae biet d6i vai cac he thdng phan biiy ky khi kho, xii ly nhu nude thai [7, tr. 245 - 254] hoac xa vao he thdng thoat nuoc. Phan chat ran con lai sau khi tach nuac c6 the tiep tue on dinh bang qua trinh ii compost [2, tr.61 - 69] hoac u tu nhien [3, tr.537 - 544]. Sau khi on djnh chdt hiiu ca con lai, phan biin nay cung cd the sir dung lam chat cai tao dat [4, tr. 30 - 36] vd vat lieu che phii bai chon lap [8].

Nghien cuu nhdm ddnh gia dae tinh biin sau phan buy ky khi sinh ra tir he thong phan hiiy ky khi udt (ggi tat la biin ky khi uot) dugc van hdnh d quy mo phong thi nghiem, tai Trudng Dai bgc Vdn Lang, de phan biiy chat thai co kha nang phdn buy sinh hgc tir cbg dau moi nong san thirc pham tren dia ban thanh ph6 H6 Chi Minh nham xem xet: (1) kha nang tai sii dung biin ky khi udt lam compost dang long trong nong nghiep va (2) cac yeu cau xu ly bo sung de chuyen loai biin nay thanh compost hay phan bdn dang Idng trudc khi tai sir dung. De dat muc tieu nay, nhimg npi dung nghien ciru sau day da dugc thirc hien:

- Phan tich thanh phan biin ky klii uot va danh gia kha nang tai su dung true tiep lam compost long sir dung trong nong

TAP CHI KHOA HOC DAI HOC VAN LANG Tran Thi My Dieu va tgk

nghiep hoac yeu cdu xii ly bo sung trudc khi tdi sii dung.

- Danh gia khd nang dp dung qua trinh phdn hiiy hieu khi biin ky khi udt de phan biiy thdnh phdn chat hiiu ca de phan buy con sot lai, khir vi sinh vat gay benh (neu con) va khir miii hoi ciia bun nay do sir bien dien cua cac san pham tir qua trinh phan hiiy ky khi ton tai trong biin.

- Danh gia khd ndng dp dung qua trinh ly tam tach nude bun ky khi irdt nham tao ra nguyen lieu cho qua trinh u hieu khi san xudt compost dang rdn.

2. PHirOTsG PHAP NGHIEN ClTU 2.1. Ddnh gia kha nang tai su- dung true tiep bun ky, khi uot lam compost dang long

Biin ky khi udt sinh ra tir he thong phdn biiy ky khi udt hai giai doan (tbiiy pbdn d nhiet do 55''C va metan hda d nhiet do 35''C), quy mo pbdng thi nghiem, xir ly chat thai co khd nang phdn hiiy sinh hpc tii cbg nong san thuc pham tren dja ban TP. Ho Chi Minh dd van hanh d cac tai trgng 3,1 kgVS/mVngd; 4,6 kgVS/mVngd va 5,7 kgVS/m /ngd, dugc lay mau 2 lan/tuan trong 12 tuan lien tiep de pbdn tich thanh pbdn. Cdc chi tieu phan tich bao gom pH, dp ki m, TS, VS, COD, BOD5, N-NH4+, N tong, P tong, kim loai nang (Hg, K, Pb, Cd, Cr, Cu, Zn, Ni), tbuoc trii sdu (Organocblorine, Organopbosphate), vi sinh vdt gay benh (Salmomella spp., Coliform, Ecoli). Cdc ket qua phdn tich nay dugc so sanh vdi lieu chuan bien hanh ve chat lugng compost va tieu chuan cua bun dd ra dat ddi vdi cac thong so kim loai ndng, thu6c trir sau, vi sinh vat gdy benh.

2.2. Danh gia kha nang ap dung qua trinh phan buy hiiu khi 6e phan buy thanh phan chat hiru co de phan huy con sot lai va khir miii hoi ciia bun kj; khi vr&t

Thi nghiem dugc thuc hien trong mo hinh be bieu khi khuay trgn hoan toan dang me. Be dugc lam bang thiiy tinh. Moi be gom CO 3 ngan, dang hinh chif nhat. Moi ngan co kich thuac L x W x H - 1 5 c m x 10 cm X 30 cm. Phia day be co tao mot gdc vat 63° de tang mire do xao trgn deu hon hgp trong be. Tong the tlcb cua moi ngdn Id 4,25 L va the tich hiiu dung la 3,5 L. Oxy dugc cap vao be bdng each diing may thoi khi dan khong khi vao ong phdn phdi cd gdn da bgt. Md hinh thi nghiem dugc mo ta trong Hinh 1.

Sau khi pbdn tich thdnh phdn, biin ky khi udt dugc cho vao be vdi lugng 2,5 kg/ngan. Cd 3 ngan dugc van hanh dong thdi vdi cimg dieu kien thi ngbiem de so sanh ket qua. Khong khi dugc cung cap vdi luu lugng 10,8 L/pbiit/ngan. Moi ngay mau dugc Idy da phan tich pH, TS, VS, COD dong tbdi theo doi mire bang cam quan miii hoi tir bim trong be. Van hanh mo hinh cho den khi dat trang thai on dinh, kbi COD trong hon hgp khong the gidm dugc nu:a va khong cdn cam nhan miii boi tir mo hinb.

COD va BOD dugc phan tich theo hudng ddn phdn tich COD, BOD trong mau bim ciia Cong ty Daiki Ataka, Nhat Ban (nay thugc Cong ty Hitachi Zosen, Nhat Ban). PH dugc phan tich bang may do pH cdm tay. Cac thdng sd khac dugc phan lich theo Standard Methods 2005.

TAP CHi KHOA HQC PAI HQC VAN LANG S6 01/2017

Hinh anh be higu khi khuay trgn hoan toan

m -ifi.

A /*

Kich thuac bS Hinh 1. Mo binh thi nghiSm hk hieu khi khudy trdn hodn toan, V = 4,25 lit/ngan.

2.3. Ddnh gi^ khS nSng dp dung qud trinh ly tam tach nii6'c bun kx khi ir6t

Biin ky khi uot dugc ly tam dh tach nude. Thanh phdn nude va biin dugc tach ra sau khi ly tdm dugc phdn tich d€ xac dinh khoi lugng va thanh phan. K6t qua phdn tich cho biSt khd ndng sii dung phdn bim da tach nude lam nguyen liSu chi biin compost va nhu cau tiep tyc xii 1; phdn nude tdch ra cho cac muc dich tdi sur dung khdc nhau hoac bao dam tiSu chudn xa thai hifn hdnh trudc khi thai vao ngudn tiip nh$n.

3. Ktr QUA VA THAO L U ^ 3.1 Thinh ph^n bun ky khi udt \k khd nang tdi su dung true tiep

Bim ky khi co pH dao dpng teong khoang 7,28 - 8,12 vd co khuynh hudng tang ddn theo thfiri gian van hanh hB th6ng phan hdy ky khi. H^ qua keo theo Id dO kiSm t6ng c^ng (phdn tich tai pH = 4,8) ciia bun cGng c6 khuynh hudng tdng tuang img va dao dgng trong khoang 3200 7500 mg/L. Trong khi do, ham lugng chdt kho trong bun l?i c6 xu hudng giam ddn theo thdi gian..Khi mdi bdt ddu van hanh h? thdng phan hiiy ky khi, biin sinh ra c6 TS khoang 6,33% va sau 3 thang TS ciia biin chi d miic 3,65%. Hdm lugng ch^t h&u co (VS) trong bun dao d0ng trong khoang 60 -70% (tinh theo kh6i lugng khd). Thanh phdn nita vd phospho tdng cOng trong biin tang ddn va dao dgng trong khoang Idn lugt la 3,2 - 6,0% (d6i vdi nita tdng) vd 0,7 -1,2% (d6i vdi P tdng). Mgt trong nhihig dde diem quan trgng la trong thanh phdn cua toai biin nay kh6ng chiia chat dpc h i nhu: thudc trii sau, kim logi n^g va vi sinh vat gay b?nh.

Uu diim ddu tien cua biin sinh ra tir h? thong phan huy ky khi udt 2 giai dogn, quy mo phong thi nghiem' Id bdo dam an toan doi vdi ddt va cay trong vi trong thanh phdn biin khdng chiia bdt ky thanh phdn thu6c trii sau dang organocblorine vd organopbosphate nao. Kit qua phan tich mdu bim ky khi udt liy tii thiing chfia bun vao ngdy 23/12/2013 vd ngdy 13/1/2014 (trinh bay tdm tdt trong Bang 1) cho thdy khdng ton tai cac thanh phan tbuoc trir sau nay trong biin.

TAP CHi KHOA HQC BAI HOC VAN LANG Trap Thj My Digu va tgk

Bang 1. Ham lugng thudc trii sdu trong bim ky khi udt

Thdng so Ham lugng (|ig/kg khoi lupng kho)

Mau ngay 23/12/2013 Mau ngay 13/1/2014

Thudc tni sau hg organocblorine

Alpha - Lindane Khong phdt hien (<10; Khong phat hien (< 10)

Beta - Lindane Khong phdt hien (< lO; Khdng phat hien (< 10)

Gama - Lmdane Khong phdt hien (< 10" Khdng phat hien (< 10)

Delta - Lindane Khong phdt hien (< 10 Khong phdt hien (< 10)

Heptachlor Khong phdt hien (< 10' Khong phat bien (< 10)

Heptachlor epoxide Khong phdt hien (< 10 Khong phat hien (< 10)

Endosulfan I Khdng phat hien (< lO; Khong phat hien (< 10)

Dieldrin Khong phat bien (< lO; Khong phat hien (< 10)

4 , 4 ' - D D E Khong phat bien (< 10 Khong phat hien (< 10)

Endrin Khong phat bien (< lO; Khong phat hien (< 10)

Endosulfan II Khdng phdt bien (< lO; Khong phat hien (< 10)

Aldrin Khdng phat hien (< lO; Khong phat hien (< 10)

Khdng phdt hien (< lO; Khdng phat hien (< 10)

4 , 4 ' - D D T Khong phat hien (< lO; Khong phat hien (< 10)

Endrin aldehyde Khong phat hien (< 10 Khong phat hien (< 10)

Endosulfan sulfate Khong phat hien (< lO; Khong phat hien (< 10)

Endrin ketone Khong phdt hien (< 10 Khdng phat hien (< 10)

Methoxychlor Khong phat hien (< 10 Khong phat hien (< 10)

Trans - Chlordane Khong phat hien (< 10 Khdng phat hien (< 10)

Cis - Chlordane Khdng phat hien (< 10 Khdng phat bien (< 10)

Thudc trir sau hp organopbosphate

Demeton (O-S) Khdng phat hien (< 10 Khong phat hien (< 10)

Phorate Khong phat hien (< 10' Khdng phat hien (< 10)

Disulfoton Khong phat hien (< 10 Khong phat hien (< 10)

Fenthion Khong phat hien (< 10' Khdng phat hien (< 10)

Khong phat hien (< 10' Khong phdt hien (< 10)

Phorate Khdng phat hien (< 10 Khong phat hien (< 10)

Sulprofos Khdng phat hien (< 10 Khong phat hien (< 10)

Coumapbos Khong phat bien (< 10 Khong phat hien (< 10)

Azinphos-metbyl Khong phat hien (< 10 Khdng phat hien (< 10)

Profenofos Khong phat hien (< lO; Khdng phat hien (< 10)

Chlorpyrifos Khdng phat hien (< 10 Khong phat hien (< 10)

Dichlonos Khong phat hien (< 10' Khong phat hien (< 10)

TAP CHl KHOA HOC BAI HOC VAN LANG So 01 / 2017

Thdng s6

Diazinon Parathion - ethyl Dimethoate

HJm linf-ng (jig/kg kh6i Iirpug kha) Mau ngjy 23/12/2013 Khong phit hi6n(< 10) Khong phat hito(< 10)

Khong phat hi6n(< 10)

MSu ngay 13/1/2014 Kh6ng phat hien (< 10) Khong phat hien (< 10)

Khong phat hien (< 10) |

Ngudn: Dugc van hdnh tai Phong thi nghiem, Khoa Cdng ngh? vd Qudn ly Moi trudng Trudng Bai h

Van Lang LTU diim quan trpng thii hai doi vdi

viSc six dung true tiep biin ky khi udt nhu mpt dang compost long la ham lugng kim loai ndng trong biin d miic chap nhdn dugc. Cho din nay, Viet Nam chua c6 tieu chudn chdt lugng ddi vdi compost dang long, do dd sii dung cdc tieu chudn hien hanh ve phan hiiu ca vi sinh de so sanh va ddnh gia.

Tieu chudn Viet Nam TCVN 7158:2002 vhphdn him ca vi sinh quy dinh ham lugng tdi da cho phep cua 5 loai kim lo i nang bao gdm Pb (< 200 mg/kg khdi lugng khd); Cd (< 2,5 mg/kg khdi lugng khd), Cr (< 200 mg/kg khdi lugng khd), Ni (< 100 mg/kg khdi lugng khd) va Hg (< 2 mg/kg khoi lugng khd).

Niu so sdnh vdi gid tri toi da cho phep theo TCVN 7185:2002, bam lugng Cr va

Bang 2. Hdm lugng kim loai nang trong biin ky khi udt so sanh vdi TCVN 7185 ; 2002

Ni trong mau liy ngay 23/12/2013 vupt qua tieu chudn, trong khi mlu ngay 13/1/2014 vdn CO ndng dp kha thdp.

Nhu vay, nguyen lieu sii dung trong h6 thdng da c6 anh hudng den chit lugng biin ky khi tao thdnh. Tuy nhien, niu so sanh vdi cac gia trj gidi han quy dinh trong Thdng tu sd 36/2010/BNNPTNT do Bo Nong nghi$p va Phdt trien nong thdn ban hanh ngay 24/6/2010 ddi vdi cac dang/;Afl« hihi ca sinh hpc sdn xudt tie nguyen li$u la rac thdi do thi, phe thai cong nghiep che bien tie nong sdn, tkirc pkdm, pke thdi chan nuoi^ (Bang 3), biin ky khi udt nay dam bao an toan va phii hgp d6 su dung nhu mgt d^ng phan hiiu ca sinh hgc.

Thong t

so

Pb

Cd

Cr

Ni

Hg

Don vi

mg/kg KLK

mg/kg KLK

mg/kg KLK

mg/kg KLK

mg/kg KLK

Nong d6 trong bun

MSu liy 23/12/2013

Khong phat hien

Kh6ng phat hien

251

141

Khong phat hien

Mau lay 13/1/2014

49

Khong phat hien

Khong phat hiSn

Kh6ng phat hien

Khong phat hien

TCVN 7185:2002

<200

<2,5

<200

<100

<2

; Phu lye sd I, TT sS 36/2010/BNPTNT: KLK - Iclidi Iwng kho

TAP CHI KHOA HQC DAI HQC VAN LANG Tran Thj My Dieu va tgk

iTu diem quan trgng thir ba doi vdi viec tai su dung true tiep bim ky khi udt nhu mdt dang compost long la trong thanh phan biin nay khdng chira Salmonella. Salmonella va fecal coliforms bi khii dang

Bang 3. Ndng dp kim loai ndng trong bim ky khi udt so vdi nguang gidi ban quy dinh trong Thong tu s6 36/2010/BNNPTNT

kk trong he thong phdn hiiy ky kbi udt 2 giai doan, dde biet do giai doan thuy phan cd gia nhiet len 55°C. K6t qua cho thdy khdng cd Salmonella, khdng phat hien Ecoli va luong Coliform thdp (Bdng 4).

Thong so

Pb

Cd

Cr

Ni

Hg

DoTi vi

mg/kg KLK

mg/kg KLK

mg/kg KLK

mg/kg KLK

mg/kg KLK

Nong do trong biin

Mau lav ' i Mau lay 13/1/2014

23/12/2013

Khong phat hien 49

Khong phat hien

251

141

Khong phat hien

Khong phat hien

Khong phat iiien

Khong phat hien

Khong phat hien

Thong tu' so

36/20I0/BNNP

TNT

<300

<2,5

khong de cap

khong de cap

<2,0

KLK = khoi lucmg kho

Bang 4. Ndng do cac vi sinh vat gdy benh trong biin ky kbi

Thong so

Salmonella

Ecoli

Coliform

Don vi

CFU/25 g

MPN/g

MPN/g

Nong do trong bun

Mau lay

23/12/2013

Khdng phdt bien

Khdng phat bien

(<3)

43

Mau lay

13/1/2014

Khong phat hien

Khong phat hien

(<3)

4

Thong tir

36/2010/BNNTT\ t

T va TC\ 'N

185:2002

0

khong de cap

khong de cap

iJu diem quan trgng thir tu doi vdi biin ky khi udt la cd chiia nhieu nguyen td cdn thiet cbo edy trdng bao gdm nita, phospho, kali va cac nguyen to vi lupng khac khong

Bang 5. Ndng do cac nguyen to kim loai cdn thiet cho cay trong c6 trong biin ky khi udt

the thieu dugc nhu dong va kem. Ket qua phan tich trinh bay trong Bang 5 cho thay trong thanh phan biin co chira lugng kali toi thiautheo TCVN 7185:2002.

Thons

so 1

K 1 Zn

Cu

Don vi

% mg/kg

KLK

mg/kg

KLK

Nong do trong bun

Mau lay 23/12/2013

1,52

Mau lay 13/1/2014

559 265

244 97

Tieu chuan

> 1,5

khong de cap

khong de cap

TAP CHl KHOA HQC DAI HQC VAN LANG So 01 /2017

T6ng ham lugng P trong bin ky khi u6t dao dOng trong khoang 0,72 -1,2% tinh theo khdi lui;mg kho (Hinh 2) va gid tri trung binh la 0,92%. Gia trj nay hai thSp hon so v6i yeu ciu theo TCVN 7185:2002 (> 2,5%). Nhir vjy dk dat tiSu chujn phSn hiJu CO sinh hpc theo tieu chuan nay, can bo sung P vao bun.

f ^ 1 0 0

%"" £ •s

1 ° ' "

Hinh 2. Tdng ham lupng P trong bun ky khi uot t?o ra tit he thfing phSn huy ky khi

uot 2 giai dojn d6i vddchit thai co kha nang phan buy sinh hpc tit chp diu mdi nong san thye phim quy md phong thi

nghi?m Tdng ham lupng nito trong bin ky khi

uot dao ddng trong khoang 3,2 - 6,0% tinh theo kh6i lupng khd va gia tri nay c6 khuynh hudng tang din theo thai gian v ^ hinh va khi tai trpng tang ddi vdi he th6ng phan huy ky khi uot 2 giai doan (Hinh 3). Theo quy dinh tai Thdng tu 36/2010/BNNPTNT, thanh phin nita tdng trong cac dang phan huu ca sinh hpc san xuit t i rac thai dd thj khdng dupe phep nhd hon 2,5%. Nhu vSy, day la mdt uu diSm nua ddi vdi bin ky khi va cho thiy kha nang tai su dung bin ky khi lam chit bd trp cho dat trdng. Trong tdng him lupng nita

cd trong bin, thanh phin N-NH4'*" chiem khodng 14,6 - 20,5% nita tdng cdng. Hdm lupng N-NH4* trong bun ky khi udt dao ddng trong khodng 0,6 - 1,1% tinh theo kh6i luong khd (Hinh 4). Phin con lai la cdc dang nita hOu ca vd N-NOs'.

7.00

:S 6.00 •

I5.00-

"1 4.00 -

"S 3.00 •

• 1 0 2.00 -

1.00

/

t t J i ' ^s^^^vvy

Hinh 3. Tdng hdm lupng nito trong bin ky khi udt tao ra t i he thong phdn huy ky khi

udt 2 giai doan ddi vdi chit thdi cd kha nang phan hiy sinh hpc t i chp diu mdi ndng san thuc pham quy md phong thi

nghiem Thanh phan chit hOu co dupe ddnh gid

bing thdng sd VS tinh theo khdi lupng khd trong bin ky khi udft dao ddng trong khoang 60 - 70%. Tuy nhien, nlu tinh theo khdi lupng udt, ham lupng nay rit thip, chi d mure 4,0 - 5,0% (Hinh 5). Hdm lupng chat khd trong bin (TS) gidm theo thdi gian. Trong thdi gian ddu van hdnh h$ thdng phan hiy ky khi, hdm lupng nay khoang 5,0 - 6,0%, nhung sau 3 thang van hanh, gia tri nay chi d mic 4,0 - 5,0%.

TAP CHi KHOA HQC BAI HQC VAN LANG Tran Thj My Dieu va tgk

Hinh 4. Ham lugng N-NIli'^ trong biin ky khi udt so vdi tdng ham lugng nita

70.00

60.00

50.00

> 30 00

20.00

1000

• VS(

^^^^m^- .

<S>"' 0-''' 0-''' o-J" o--'' <><' oO ts--'' t,^'' t!-"

/n khoi lirong irat) " VS (% khfii lupng kho)

Hinh 5. Ham lugng chat him ca tinh theo VS (% khoi lugng udt vd % khdi lugng khd) trong biin ky khi udt tao ra tir he

thong phdn hiiy ky khi udt 2 giai doan ddi vdi chat tbdi co kba nang pbdn hiiy sinh hgc tu cbg dau moi nong san thuc phdm

quy md phong thi nghiem

Ndi chung, biin ky khi tij he thong phan hiiy ky khi udt 2 giai doan quy mo phong thi nghiem su dung de phan buy chat, thdi cd khd ndng phan buy sinh hgc tir chg ndng sdn thuc pham cd kha ndng tdi sir dung true tiep nhu mgt dang compost long de bd trg cho dat trong vi trong thanh phdn ciia lo i biin nay khong cd chira cac hgp chat dgc hai nhu tir thudc tru sdu, cdc kim loai ndng cung nhu vi sinh vdt gay benh. Thanh phan dinh duong K, N va mgt sd nguyen td vi lugng nhu Cu va Zn ciing cd mat trong biin. Tuy nhien, tiiy theo yeu cdu dinh duang va vi lugng cua tung loai cay trong, can phdi bd sung them P va C. 3.2. Khd ndng ap dung qua trinh phan huy hieu khi de phan hiiy triet di cdc thanh phdn chat hiru cd con lai va khu-mui hoi cua biin ky khi uot

Thi nghiem dugc thuc hien bdng each tbdi kbi biin ky khi udt Idy tir hk chua biin de danh gid muc do tiep tue phan buy phdn chat hiru ca chua kjp phan huy trong qua trinh phdn hiiy ky khi cung nhu kha ndng loai bo miii boi cua biin. Biin dugc cbo vao ba ngdn giong nhau cua md binh nhu da mo td tren, dugc sue khi va lay mdu hang ngay cho den khi bam lugng chat khd (TS) va chdt biiu ca (VS) trong hon hgp va thanh phan sCOD cua pha Idng khong giam nD:a. Ket qua thi nghiem cho thdy ham lugng chat ran tinh theo TS tiep tue giam dugc khoang 1% (tir khoang 4,5 - 5,0% xudng cdn khoang 4,0 - 4,2%) va thanh pbdn VS (tinh theo khdi lugng khd) gidm them dugc khoang 1% (Hinb 6). Diiu do cd nghTa la hdu bet cac chat hiru ca dd bi phan hiiy gan nhu hoan toan trong he thdng phan buy ky khi. Nong dd sCOD ciia pha Idng trong hon

TAP CHi KHOA HOC £)AI HOC VAN LANG So 01/2017

hgp ciing giam dan theo tbdi gian thdi khi vd dat trang thai dn dinh sau 8 ngay (Hinh 7), tuang ung vdi sCOD giam tir 1600 mg/L xudng con 1200 mg/L. Ben canh dd, miii hoi ciing gdn nhu khdng cdn niia sau khodng 1 - 2 ngay thdi khi. Nhu vay, neu dp dung phan buy hieu kbi biin ky khi nham bao dam dn dinh hoan toan biin, thdi gian thdi khi can khoang 8 ngay.

4 Ngay 6 8

A Reactor 2 x Reactor 3

Ngay X Reactor 1 + Reaelor 2 .

Hinh 6. Bien thien TS (%) va VS (%) cua biin ky khi theo thdi gian thdi khi

3.3. Ly tdm tach nude biJn ky khi uot trudc khi che bien compost

Biin ky khi udt dugc ly tdm vdi tdc do 3000 vong/phut trong 30 phiit cd thi tdch biin thanh 2 pha. Pha long chiSm 93% khdi lugng biin ban ddu va phdn con lai la pha ran. Ham lugng chdt khd trong pha rdn dugc tach ra tir qua trinh ly tam dat 73,5%

vdi VS tinh theo khdi lugng khd dai 70%. Trong kbi dd pha long co COD ciia dung dich sau khi ly tdm d muc 1600 mg/L. Phan chat Idng nay cdn tilp tue dugc xu ly de loai bd thanh phan chat him co (tinh theo COD) de dat tieu chudn xa thai nude thai theo quy dinh hien hanh (QCVN 40:2011/BTNMT). Nhu vay, ngu ly tam tach nude, pha ran cd the dugc phdi tron vdi mdt sd nguyen lieu khac de u va che bien compost. Tuy nhien, dieu bat lgi la phdn pha Idng chiem ty le kha Idn can dugc xir ly nhu xir ly nude thai trudc khi thai bo. Dieu nay lam tang them chi phi khong co lgi trong toan bg he thdng tai chi chdt thai cd kha nang phdn biiy sinh hgc dl thu h6i khi.

sCO

D (

mg/L

)

* *" a A « ., *• *

- !£l ffl

0 2 4 6 8 10

Thin gian (ng^y)

• Reactor 1 A Reactor 2 - Reactor 3

Hinh 7. Bien thien sCOD ciia pha long trong hon hgp biin ky khi theo thdi gian

thoi khi 4. KET LUAN VA KIEN NGHI

Ket qua thi nghiem cho phep riit ra nhung ket luan chinh sau day:

- Cd the tai su dung true tiep biJn ky khi udt nhu mgt dang compost long de bon cbo cay trdng vdi dieu kien: (1) bo sung them thanh phan P, (2) do kich thudc hat biin cdn lai trong biin ky khi udt rat mjii nen can kiem sodt lugng bdn cho ddt trong

TAP CHI KHOA HOC DAI HOC VAN LANG Tran Thi My Dieu va tgk

de tranh tinh trang lam gidm do tcri xdp cua tieu chudn xa thai cho phep theo quy dinh

dat va (3) do ham lugng chdt rdn trong bun hien hanh ciia Viet Nam va do do se lam

thap (chi khoang 3 - 5%) nen chi phi van tang chi phi dau tu va van hanh todn bg he

chuyen la mgt trong nhung yeu td Igi ich thdngpbdnhuyky khi thu bdi biogas.

kinh te can xem xet. De tang kha ndng tai sir dung bim ky

- Miii hdi cua biin cd the kiem soat khi udt trong thuc te can:

bdng each tbdi khi bim ky khi trong 1-2 Nghien cim su dung cac loai che

ngdy; pham vi sinh de gidm miii hdi thay vi dimg

- Neu ly tdm, tach nude ciia biin ky khi phuang phap tbdi kbi.

cd the tao ra dugc phdn chdt ran (DM^ Nghien ciru thic nghiem lieu lugng

73%, VS = 70%)) cd the phoi trgn vdi cac bim ky khi udt su dung nhu pbdn hihi ca

nguyen lieu khac de ii compost. Tuy nhien long cho cdc loai cay cdng nghiep va edy

phan nude tach ra chiem 93% bdn hgp biin an trai khac nhau.

ky khi udt vdn cdn ham lugng chat hiiu ca - Nghien cuu danh gia chi phi - lgi ich

cao (COD khoang 1600 mg/L) can phai kbi tai sir dung true tilp biin ky khi udt nhu

dugc tiep tue xtr ly nhu nude thai de dat phdn him ca.

TAX LIEU THAM KHAO

i. Bauer, A., Mayr, H., Hopfner-Sixt, K., Amon, T. (2009), Detailed monitoring of two

biogas plants and mechanical solid-liquid separation of fermentation residues. J.

Biotechnol. 142.

2. Bustamante, M. A., Restrepo, A.P., Aiburquerque, J. A., Perez-Murcia, M. D., Paredes,

C , Moral, R., Beraal, M. P. (2013), Recycling of anaerobic digestates by composting:

effect of the bulking agent used. J. Clean. Prod. 47.

3. Drennan, M. F. DiStefano, T. D. (2010), Characterization of the curing process from

high-solids anaerobic digestion. Bioresour. Technoi. 101.

4. Gong, H., Yan. Z., Liang, K. Q., Jin, Z. Y., Wang, K. J. (2013), Concentrating process

of liquid digestate by disk tube-reverse osmosis system. Desalination 326.

5. Kythreotou, N., Fiorides, G., Tassou, S. (2014), A review of simple to scientific models

for anaerobic digestion. Renewable Energy 71 (2014).

6. Li, v. . Park, S. Y., Zhu, J. (2011), Solid-state anaerobic digestion for methane

production fiom organic waste. Renew. Sustain. Energy Rev. 15.

7. Mangwandi, C , JiangTao, L., Albadarin, A. B., Allen, S J , Walker, G. M. (2013),

Alternative method for producing organic fertiliser from anaerobic digestion liquor and

limestone poweder: high shear wet granulation. Poweder Technoi.

8. Mouat, A., Barclay, A., Mistry, P., Webb, J. (2010), Digestate market development in

Scotland. Natual Scotland. Natural Scotland Scottish Government, Scotland.

TAP CHl KHOA HQC BAI HQC VAN LANG So 01/2017

9. Paavola, T. and Rintala, J. (2008), Effects of storage on characteristics and hygienic quality of disgestates from four co-digestion concepts of manure and biowaste. Bioresour. Technoi. 99.

10. Tchobanoglous, G., Tbeisen, H., Vigil, S., (1993), Integrated solid waste management: Engineering principles and management issues. McGraw Hill, Inc. New York, St. Louis, San Fransico, Auckland, Bogots, Caracas, Lisbon Madrid, Mexico, Milan, Montreal, New Dehli, Paris, San Juan, Singapore, Sydney, Tokyo, Toronto.

11. Walsh, J. J., Jones, D.L., Ewards Jones, G., Williams, A. P. (2012), Replacing inorganic fertilizer with anaerobic digestate may maintain agricultural productivity at less environmental cost. J. Plant Nutr. Soil Scien. 175.

12. Zeshan, Visvanathan, C. (2013), Evaluation of anaerobic digestate for greenhouse gas emissions at various stages of its management. International Biodegradation 95 (2014).

Ngay nhan bai: 07-11-2016. Ngdy bien tap xong: 18-11-2016. Duyet dang: 15/12/2016