Tap chi Khoa hgc Tnrang Dai hpc Cdn Tho Phdn .4: Khoa hpc Tir nhien. Cong ngh? vd .Moi Inrang: 28 l20l3i 38-46
•_ ••x. Tap chf Khoa hpc Tru'dng Dai hoc Can Thd website: sj.ctu.edu.vn
SU" DUNG VAT LIEU BJA PHU'ONG 0 E LOAI DAM VA LAN TRONG NU'dC THAI CHE BIEN THUY SAN
Le Anh Kha', Pham Viet Nir' va Co Thj Kfnh'
' Khoa Mdi trudng & Tdi nguyen Then nhien. Trudng Dgi hgc Cdn Tha Thdng tin chung:
Ngdy nhdn: 01/05/2013 Ngdy chdp nhdn: 29/10/2013 Title:
Using local materials as attached media for microorganism for nitrogen and phosphate removal in seafood processing wastewater Tdkhda:
Xii- ly mrdc thdi, nitrate hda.
kbit nitrate, hdp phu ldn, nuac thdi che bien thuy sdn Keywords:
Wastewater treatment, nitrification, denitrification.
phosphorus adsorption, seafood processing wastewater
ABSTRACT
This research was carried out in order to treat nitrogen and phosphate in seafood processing wastewater for preventing eutrophication of receiving water bodies. A continuous treatment system was established based on nitrification, denitrification and phosphate adsorption processes by microorganisms in attached media made from local materials including porous concrete blocks and acid sulfate soil. Results showed that the porous concrete blocks were a suitable media for attached-growth
microorganism which performed denitrification reaction. It was recorded that this treatment system was capable of removal efficiency of nitrogen and phosphorus of 89.7% and 82.1%. respectively. The indicated effluent quality for total nitrogen, nitrogen, phosphate, and total phosphorus reached the national technical regulations on the Effluent of Aquatic Products Processing Industry (QCVN 11:2008/BTNMT, column A).
TOM TAT
De tai dugc thuc hien vdi muc tieu logi bd dgm vd ldn trong nudc thdi che biin thiiy sdn trudc khi dua vdo mdi trudng tu nhien nhdm ngdn ngira su phii dudng hda. Mgt hi thong xit ly lien luc dugc bo tri vdi vdt lieu tyr chi su dung cdc khdi bi tdng rdng vd ddt phen Id gid the cho cdc vi sinh vdt thyc hiin cdc phdn ung nitrate hda, khu nitrate vd hdp phu ldn trong nudc thdi cua nhd mdy chi biin thuy sdn. Kit qud nghien cuu cho thdy cdc khoi bi tdng Id vdt liiu lot de ldm gid the cho vi sinh vgt bdm vd thirc hiin phdn ung khu nitrate. He thdng dgt hiiu sudt xu ly dgm vd ldn trung binh ldn luat dgt 89.7% vd 82.1%. Chdt lugng nudc thdi ddu ra thdng qua cdc chi tieu nhu tdng dgm. nitrate, phosphate vd tdng ldn deu dat quy chudn Viit Nam doi vdi chdt luang nuac thdi cdng nghiip che bien thiiy sdn (QCVN11:2008/BTNMT. loai A).
1 GIOI THIEU
Cling voi sy phdt trien chung eua nganh nudi trong thuy sdn d cac nudc, nganh che bien thuy san d Viet Nam phit triln rat nhanh chdng. Bin canfa nhihig lgi ich Id mang vi ngufin ngogi tl ldn nhd xudt khiu va cung cdp mdt luang thyc phim quan frpng cho nhu cau xa hdi, nganh cfal biln thiiy hii sin cung phdt thii ra nliilu chat thai. Die tinh cua nudc thai nginfa cfai biin tfauy sin chira nfaiiu chit
hiJu CO vd dinh dudng cao (dam va lin), tgo dieu kien thuan loi cho hiln tupng phu duong trong cac thuy vyc. Sy phat trien manh, chet di va phan huy xic cua cac loai thyc vat philu sinh nhu tio se phdng thich ra cac dfic tfi lam anh huong din doi sdng thuy sinh vgt John Rodgers (2008). Sy phin huy cac chit hitu co frong nudc lam tieu faao lugng ldn ngudn oxy frong thuy vuc gay ra su thiiu hut oxj' vdi cic loai ca, tdm va cac thuy sinh vat khic.
Tap clli Kboa bgc Tnr&ng Dai bgc Cdn Tho Pb^n A Kboa hoc Tu nhien. Cong nglie vd Mdi tnrang- 28 (2013/: 38-46 Hiln nay. da cd rit nhilu ngfailn ciiu vl van de
XIT ly ham lupng dam vi ldn cao frong nudc thai bang cic bi|n phdp khac nhau nhu phucmg phip hda ly. Tuy nhiin, nhiing phuang phdp nay td ra khdng cd nhilu uu diim vi nd co thi tgo ra cac sin phim fi nhilm thii cdp ma cic chit nay dfii khi rat khfi khan va tdn kem dl xir ly Green vi Shelef, (1994). Theo Halling-Sarensen va Jargensen (1993), Metcalf va Eddy (2003), Luong (2002) cac phucmg phip xir ly dinh duong dam vd lan frong nudc thai nhu: hap phu, frao dfii ion, khu iiiia sinh hpc (cd gii bam hogc biin hoat tt'nh), khu nifrate hoa hpc, thdm thdu nguac, dien thim tach va khu xiic tic li nhihig phuong phdp cd the logi bd nitrate frong nudc. Trong do phuang phip xii ly bang phuang phap sinh hpc cd gii bim vd su dyng vat lilu hip phy cd im thi ve hieu qua xu 1>'. chi phi thdp va de van hanh. Nghiin cmi cua Ll Anh Kha vi Masayuki Seto (2003) cho thay cdc khoi bl tdng rong va dat nung li cac vgt lilu gii bira vd hap phu rat hieu qua de loai bd dam va lan frong nuoc thai.
Theo Drizo et al (1999) vi Herman. 2007 mdt sd chat nhu bd xit, da phien set. dit set, khoang va than li nhOng vit li|u co khi ning hdp pfau hieu qua ldn frong nudc thai. Do thdnh phan cdc vgt lieu niy cd chua khoing chit cd cic ion sat va nfadm hogt dpng ho$c cdc nhdm oxit tren be mat cd the phan irng vdi ion phosphate tgo ra cdc hpp chat kit tua chiia phosphate va de ding logi lin ra khdi he thdng. Theo Ll Anh Kha vi Masayuki Seto (2003), SLi dyng khfii be tdng vi hgt dat nung cd thi logi bd dam frong nudc thai vdi hieu suit dat 85%.
Do do, nghien ciiu sii dung vdt lieu dia phuong dl xii ly dam va ldn trong nuac thai chl biln thuy sin da dupe tien hanh voi mue tieu sir dung cdc logi vit li|u don gian vdi chi phi thap va dl tim de lim gii the dung frong h | thdng xir ly dam va lin trong mrdc thai dya trin hogt ddng ciia cac vi sinh vgt bim dinh va phuang phap hdp phu.
2 PHU'ONG PHAP NGHIEN ClTU 2.1 Phuvng tiln nghien ciru
Cac dung cy bfi frf thf nghiem chinh bao gfim:
- Bl nhya cd the tich 300 L. bl composite co thi tfch 45 L v i i 000 L
He thdng cung cdp dinh duong ty ddng Miy sue khi vi may bom chim 2.2 Dia diem nghien cuu
Thi nghiim dupe tien hanh lgi Phdng thi nghiim Chat lugng mfii trudng. Bp mdn Khoa hoc Moi tnrong. Khoa Mdi tnrong & Tai nguyin Thien
nhien, Truong Dai hpc Cdn Tho. Ngudn nudc that cdp cho thi nghiim li nudc thii tir nha may chi biin thiiy san Cafatex.
2.3 Vat lieu nghien ciru
Vdt liiu 1: Khdi be tdng rong dugc lam tir da (dudng kinh viin khoing 1-2 cm), xi mdng va cat.
Dd sau khi frpn vdi xi mdng vd cat dupe due thinh kfadi Igp phuang rong cd canfa khodng 10 cm (Hmh 1).
Cich tao dp rong ciia kfadi bl tfing duoc thyc hiln bdng each trpn deu da 1-2 cm vdi hfin hpp long 3 cit 1 xi raing, sau d6 sip xip tiing vien da vdo mpt khuon gd hinh lap phuang cd canfa 10 cm sao cho khdi be tfing c6 dp rfing cao ma vdn ddm bao dugc dp chdc chin ciia kfadi be tfing, do thyc hien bdng phuang phdp thii cfing nin cac khfii bl tdng cd dp rdng tuang ddi ddng nhdt. Sy anh hudng cua dp rdng giua cac khdi bl tfing lln hieu qua xii ly co dfi biin ddng khfing ldp dd the hien qua cic sfi lieu thyc nghiem. Cac khdi be tfing cd dp rong 37.5±2% dugc bfi tri vao he thdng vm ti sd the tich vat lieu so vdi thi tich bl xu ly la 75.5+4%.
Bl cip chfnh la bl nhya 300 lit li bl cip nudc thii ddu vao hi thdng xii ly.
Vgt Hiu 2- Dat nung, li loai dat phen dugc lay d huyen Diic Hda-Long An, mail dat dugc lay cich lop ddt mil khoang 40 cm. Ddt sau khi thu dugc dem ve phong thi nghiim va frpn deu sau dfi tao thinh khoi try frdn cd chilu dai 1-4 cm, dudng kfnh 0,2-0.4 cm. nung vdi nhilt dp 550°C frong 4 gid (Hinh 2). Dit phen vdi ddc tfnh hinh thinh trong dilu kiln khii hay nung thiiu oxy, vdi thanh phin cd ham lugng sat vd nhfim cao, loai vdt li|u niy cd tiem nang h ^ phu cdc dgng lin hda tan manh, do do vat lieu dat phen nang dugc sy dung de bd tri lam vat lieu hap phy lin frong nudc thai.
Hinh 1: V^t lieu kfadi be tong rong
Tap chi Khoa bgc Tnrang Dgi hgc Cdn Tba
Hinh 2: Vat li|u d^t phen nung Be giii myc, be 1, bi 2 la hi composite cd thi tich khoang 35 lit. Bl giu: muc Id bl composite c6 thi tich 35 lit cd gin phao gia myc de fin dmh lugng nudc dau vao cua h | thfing xii ly. Bi 1 vd bi 2 Id cdc bl chiia vdt lieu bao gdm khdi bl tong rdng va ddt nung.
Cac bi diing trong thi nghiim dugc bo tri chenh l|ch theo dp cao so vdi mgt dat nhu sau: bl cip
Phdn .4: Kboa hoc Tu nhien. Cong nghe vd Moi tnr&ng- 28 (2013): 38-46 3 m, be giii muc 2 m, be dat nung 1,5 m, bl bl tdng 1 m. De tan dung ndng lugng ciia frgng lyc van chuyen nudc thai giua cac be nhdm tiet kiem ndng lupng cho viec bom nudc thai qua cdc be frong qud trinfa tfaf nghiim.
2.4 Bo tri thi nghiem
2.4.1 Tien xir ly nudc thdi che biin thuy sdn trudc khi dugc diing di bo tri trong cdc thi nghiem
Nuo€ thai che bien thiiy sdn thd frude khi diing de bfi fri frong cae thi nghiem dugc tien xir ly qua 2 giai doan bao gfim giai doan amdn hda (d bl ty hogi) va giai doan nifrate hda. Qua giai doan arafin hda, phin ldn cac dgng dara huu ca trong dilu kiln yim kfai dugc cfauyen hda vl dgng NH4^ nlid qua frinfa amdn hda. Sau do, nudc thai sau giai doan amdn hda dugc oxy hda bdng each syc khi de chuyin dgm amdn tfainh dam nifrate. Sau giai doan ndy nudc thdi vdi thanfa phin dgm faien diln phdn lon la nifrate se dirge diing lam ngudn nudc thai diu vao ciia he thfing xii ly frong nghiin ciiu nay.
Nirac thai che bien thuy san
Be tu hoai
(be amon hoa) Be nitrate He thong khu Hinh 3: Tdm tdt cic bude tien xd ly nirdc thai tir nha mdy efae bien tfaiiy san Cafatex
trirdc khi diing trong cic thi nghiem Do COD dau vao ciia h | thdng da gidm dang ke
qua cdc giai dogn tien xit ly. Metcalf va Eddy (2003) va George et ai (2003), phan img khii nifrate hda dl chuyin hda cac dgng dam nifrate thdnh khi nita la phan img xay ra nhd vai frd cua cac vi sinh vat ty dudng thieu khi. B^ thyc hiln phin Omg niy, nifrate si dugc sii' dyng nhu Id chit nhdn di^n tir frong qua frinh tdng hgp ndng luong tir cac hgp chat chiia carbon trong mfii frudng dl cung cdp ndng lugng cho te bio va sin sinh tl bio mdi. Theo dd, vfii die tinh ciia nudc thii ddu vio diing frong nghiin cuu nay cd ham lupng carbon rit thip, nin him lugng carbon tir dudng saccharose si dupe bd sung de cung cip thim ngudn ndng lupng cho cic vi sinh v^t hoat dOng vdi luu lupng la 8 lit/gid.
2.4.2 Thi nghiim xir ly mrdc thdi bdng hi thdng bi chira ddt phen vd bi be tdng
Tiin hinh 2 dgt thu nudc thii chi biin thiiy sin tir nha miy Cafatex. Moi dgt thu nudc thii tir nhi miy cd tfainh phan nudc thai dau vdo khdc nhau dupe thyc hi|n 2 dpt nitrate hda. Sau dd lien hanfa bd fri tfai nghiim kiem tra hi|u qud xii ly eiia he
thfing voi 3 lin lap lai tuong ling.
Thf nghiem dugc bd frf theo frinh ty bl chira ddt phen nung trudc, tiep den la be chiia cdc khfii be tdng rong. Trinh ty bfi fri cac bl phin iing nhu frln li nhim thyc hien phan iing hdp phu ldn frong nudc thai frudc, sau do thyc hien phdn iing kfaii nifrate hoa o giai dogn tiep theo dl logi dam ra khoi hi thdng.
Dilu kiln xir ly ciia he thfing: luu lugng 8 lit/gid xac dinh bdng fing dong, phdn nudc thii cfaiim cfad frong bl pfaan iing sau kfai lay vat lieu ra khoang 40,0 L xac dinh bang fing dong, thoi gian tdn luu ciia he thfing khoang 5 gid, ngufin carbon dl bfi sung vio fae tfafing dupe chpn li saccharose (dudng thyc phdm). Ca 2 bl thf ngfailm diu dugc thuc faien frong dieu kien thilu khi (khdng syc khi).
Thi ngfailm dugc bd fri lap lai 2 lan. Kfai he thdng dgt frgng thii dn dinh thi lien hanfa thu mdu qua 2 dot bfi frf thi nghiem.
Nudc thai ciia timg dgt thu tai xi nghiep sau khi xir ly sa bd tiln hanh cho qua he thfing nhu mfi td d Hinh 4.
Top chi Kltoa hoc Tnmng Doi hoc Cin Tha FMn A-Khoa hoc Tit nhin. Cong nghe vo Moi Ittmtg^ 2S (2(111): iS-46 «ll
Be cap
J Carbon
Be giii muc
Bi dit nung
<7)
Daura Be be long
* Chu thich- I. 2. 3.4 ldn luol Id cdc vi tri thu mdu Voi I (HK) - Nirdc thai ddu vdo (sau giai doan nitrate hda nung CO bo sung carbon. 4 (BT): Be be long
2.5 Phirong phdp thu va phan tich mau 2.5.1 Phuangphdp thu vd bdo qudn mdu Thu vi bio quan mau: theo phuang phap frong tiiu chuin Viet Nam (TCVN 5999:2005).
2.5.2 Cdc chi lieu vd phuang phdp phdn tieh Cac chi tieu sinh hoc: Tfing vi sinh vat dj dudng (heterofrophic bacteria), long coliform, Escherichia coli (£. coif) dugc xdc dinh theo phuong phdp dim khudn lac (Forming Colony Count method).
Cic chi lilu hoa ly dugc phdn tich tai phong thf nghi|m chit lupng mdi tnrdng Khoa Mfii Truong
& Tii nguyin Thien nhiin, Trudng Dai hpc Cin Tha (Bangl).
Bang 1: Cdc chi tiiu hoa ly va phuong phap phin tich
Chi tieu Phinmg phap phan tich Nhilt dp
Hinh 4: Str d i bo tri thi ngfaifm
hiSu khi). 2 (DN). Sau be ddi nung. 3 (HKC) Sau bi ddt
Do bang nhiet k l (TQ) pH. EC
DO
Do bang may do TOLLEDO Do bing may do DO YSl 5000
COD Xac dinh bing phuong phap
diing KMn04 NO;-. NO5-. NH4 TN. TP. TDP.
P04-"
+ Do bang may sac ky ion Shodex CDS
Do bdng phucmg phap hdp thu quang phfi
2 5.3 Phuong phdp xir ly sd liiu Sir dyng phan nilm excel 2003 di ve do thi.
- Su dyng phan mim SPSS 13.0 dl xir !y sfi lieu (Paired samples T Test di so sdnh su khac bill).
3 KET QUA VA THAO LUAN 3.1 Ket qua tbi ngfailm xir ly nudc thai Oku vao vd dau ra qua 2 lan laip lai
Trong thinh phin ciia nudc thdi thu tir nha may Cafatex con chira cic chat cin xir ly vdi ham lupng rat cao (Bdng 2).
Bang 2: Su biln dong cac chi tieu COD, TN va TP (mg/L) cua nude thai nhd may Cafatex qua 2 Idn ldp lai thi ngfaifm Chi tiiu Nho nfaat Ldn nhit Trung binh COD 192,0 232,0 206,7 TN 89,9 96,9 92,8 TP 32.6 36.2 34,1 Nhiet do qua 2 dgt thi nghiim xir ly nudc thdi ddu vao va dau ra sau cic giai doan xii Iy ciia he thdng bien ddng frong biln dO hep khodng 28±0,9"C do luong nudc dy tru trong bi cdp ldn khoang 300 L cung cdp liln tuc mpt lugng nudc thii cho he thfing voi tfic dp ddng fin djnh la 8 L/gid tgo thinh mpt he cin bdng dpng frdnfa dugc dang kl anh huong ciia biln dfing nhilt cua khfing khi, cimg vdi dilu kiln bo tri thi nghiim frong phdng giup fin dinh nhilt dp cho he thfing.
Kit qud Bang 3 cho thdy thdnh phin hda ly ciia nudc thdi thi nghiem qua 2 dgt thu mlu khi bien dpng giira nudc thai dau vio sau giai doan nifrate
p chi Kboa hgc Tnr&ng Doi hgc Cdn Tho Pban .4: Khoa bpc Tir nhien. Cong ngbe va .Moi tru&ng' 28 (2013/ 38-46 hda hiiu kfai (HK), giai dogn hdp phy bang dit
nung (DN), nudc thii sau khi bd sung carbon (DNC) vi sau giai dogn khu nitrate sii dung cic gii the be tfing rong (BT). Theo dd, hdm lugng oxy hda tan tai bl hieu khi (HK) dgt gid tri cao nhit so voi cic be con lgi dilu niy cfao thiy tai bl HK co him lugng oxy hoa tan cao dieu kiln niy khfing thich hgp cho vi sinh vdt thyc hi|n qui frinh khu nitrate, tuy nfailn oxy hod tan gidm ddn ldn lugt qua cic be DN, DNC vd BT cho thay vi sinh vat dd tiiu thy dugc ngufin carbon them vao sy phan huy cdc hgp chit carbon di tiiu ton rit nhieu oxy hod tan faon niia hdm lugng oxy faoi lan thip nhat d be BT cho phep ta phdng dodn phan iing khir nitrate Bang 3: Si^ bien dpng cac efai tieu DO, EC, pH, dd
hod da diln ra raanh nhdt d bl BT. So sanh lugng oxy hod tan tgi diem DNC gi&a 2 dgt nhgn thay cd sy khac bi|t lon, d dgt 2 vi sinh di quen vdi ngufin carbon thim vao nen dd phin huy nhanh hem lim cho oxy hoa tan d dgt 2 thdp han dang kl, chi tiiu EC CO xu huong giam dan lan lugt qua cac be HK, DN, DNC va BT cho thdy lugng ion phan ly cimg giara dan tuong ung do Ec cd liln quan mat thilt din ndng dp cac ion pfain ly, dilu niy phii hgp vdi gid thuyet la cd mdt lugng nifrate mat di do qud frinh khii nifrate da xay ra frong he thdng xix ly.
Cac gii fri do dugc frong bang the hien cho mfit he thfing kfair nitrate dang dugc thuc hiln tdt.
due d 2 lin lap lai thi nghifm
Mau DO(mg/L) EC (us/cm) pH
HK(1) DN(2) DNC(3) BT(4)
4.2±0,5 3.4±0,9 3.4±0,3 0,3±0.1 4.3±0,1 2.6±0.3 0.7±0.2 0.3±0.1
974,3±58.7 930,7±55.3 902.0±84.0 892,3±67.7 916,8±1,2 829.0±13.0 824,5±62.5 801.5±3.0
8.2±0.3 6,1 ±0.2 6,3±0.1 6.3±0.1 8,0±0.2 6.3±0.04 6.3±0,1 6.3±0.05 HK(1)
DN{2) DNC(3) BT(4)
Hinh 5: Bien d^ng ham lirgng COD qua cac giai do^n xir ly ff 2 dgt thf nghidm
200.0 •
J 150.0 •
O 100.0 •
u
50.0 • 0.0 •
t m
i
i
Vt}'
\uf>at 1 a&as2 I Biin dpng ham lugng chit hiiu ca trong h |
thfing thi nghiim thfing qua chi tiiu COD dugc thi hien d Hinh 5. Theo Hinh 5, cd tiii suy luin rdng vi sinh vdt cd thi dimg saccharose nhir la nguon carbon cho cac faoat dpng sdng cua chiing. Ham lugng COD diu vdo (sau khi thu tir nhd may chl biin tiiuy sin) klioing 206,7 mg/L, COD sau giai doan tiin xii ly d bi (HK) la 15 mg/L, gia trj COD gidm mgnh sau giai dogn tiln xii ly la do: giai doan tiin xir ly bao gdm 2 giai doan Id amon hod va nifrate hoi ci 2 giai dogn nay deu tieu tfin rat nhilu ndng lugng cho vi sinh vit hoat dpng dl phan huy chdt huu CO gidi phong khi CHj frong giai dogn amdn hod vi khi CO2 giai doan nifrate hda lam cho ham lupng COD ciia nudc thai ban ddu gidm manh. COD d nudc ddu ra chi cdn lai d miic
khoing 40 mg/L la do trong qua trinh xu ly he thfing cdn bd sung mpt ngudn carbon tir ben ngoai (Hinh 4) cho vi sinh v§t hoat dfing, lim cho COD tgi vi fri DNC tang lln hon 200 mg/L va lugng carbon ndy phin lon cung cip ndng lugng, mot phin dugc vi sinh vat hap thy lam tang mat sd vi sinh vat (Hinh 8) lugng sinh khdi niy gop phan lam cho COD dau ra khodng 40 mg/L. Nlu tinh lugng COD dau vao bao gfim COD tir lugng carbon cung cap tii bin ngoai thi hieu suit xur ly COD cua he thfing dat tren 90%.
So sanh gid tri COD giiia cic cip HK vd DN.
DN va DNC, DNC vi BT cho thiy d cap DNC-BT cd sy sai khdc cd y nghia thfing kl (p<0,05), nhu vay kit qua niy phii hpp vdi lap luin fren.
Tap clli Khoa hpc Tnr&ng Dgi hgc Cdn Tho Phdn A: Kboa hoc Tu nhien. Cdng nghe vd Mdi tru&ng: 28 12013>: 3y^-46 3.2 Hi^u qua xir ly d?m, ldn va vi sinb qua
he thdng thi nghiem 3.2.1 Hieu qud xu ly dgm
Kit qud xii ly dgm qua cie giai doan frong he thfing xir ly nudc thai dugc trinh bdy qua Hinfa 6, cho thdy phdn ldn faam lugng dgm hiln dien frong nudc thai dau vao d dgng nifrate (NOj'-N) vdi ndng dp d miic khoang 45 mgN/L. Sau khi qua be bl long ndng dp N-NO?" cdn khoang 1,9 mgN/L.
Tuong ty nhu d dgt 1. ham lugng NHi" d miic rit
thdp sau he thdng xir ly khoing 0.5 mgN/L. Hieu sudt xu ly dam tnmg binh cita 2 dgt bfi tri thi nghiem khoing 89,7%. Vd haro lugng cdc chi tieu tdng dam \ i cac dang dgm ion (nitrate, nitrite va ammonium) diu ndm frong khoing cho phep ctia lieu chudn chat lugng nudc thai cfing nghiep che biin thiiy san tnrde kfai tfaii vio cic ngufin nuoc duge dimg cho muc diefa cip nudc sinh hoat (QCVNn:2008/BTNMT. logi A) vd lilu chuin chdt lugng nudc mat dimg cho myc dich tudi lieu tiiuy lgi (QC VN08:2008/BTNMT, loai B1).
J l ^
T 1 n TN a N - N 0 3 - • N-.N02- D N-NH4+ Dgt 2 O TN n N'-N03- D N - . \ 0 2 - D N-NH4+
hda, giiip qui frinh logi bd nifrate dien ra vdi hieu sudt cao.
Hinfa 6: Ham lugng cic dang dam qua cac giai doan xu ly trong 2 dot tfai nghiem So sinh gii tri cac chi tieu dam d dang ion vi
tfing dgm giCta cdc cap HK va DN, DN vd DNC, DNC va BT d ca hai dgt cho thdy cap DN-DNC vi DNC - BT cd sy sai kfaic cd >' nghia thdng kl (p<0.05). nhu vay qui frinh khir nitrate xay ra cd y nghTa d bl bl ldng.
Cd thi thay rang he thdng xir ly gdn nhu logi bd hoan todn ham lugng nita frong nude thdi. Dilu nay cho thiy cac khdi bl tfing rong li vat lieu bam dinfa hieu qui cho cac qudn thi vi khuin gliip loai bd ham lugng carbon va nita ttong nudc thai ra khdi he thdng. Theo Halling-Sarensen vd Jargensen (1993). vi De Lucas et al. (2005), frong diiu kien yem khi. cic vi sinh vit dj dudng frong nudc thai sii dung hdm lugng carbon va nifrate hogc/vi nifrite lan lugt la ngudn cung cdp elecfron vi nhin electron dl tgo ndng lugng cho hogt ddng sdng ciia CO the va phin chia tl bdo. tfaeo dd. mac dii sachaiTose dugc bd sung vdo he thfing vdi him lugng cao (DNC). carbon frong nudc thai sau giai dogn na>' giam ding kl di sau bi khii nifrate hoa frong cd bd sung gia tiii be tdng (BT). Diiu ndy cung cho thi\ dudng sacharrose cd hieu qua trong
\ ai fro cung cap ngudn carbon cho hogt ddng cua cic \ i sinh vat di duong frong giai dogn khii nitrate
Vdi hieu suit xii ly dam trung binh khoang 89,7% hdm lugng dam cdn lai dudi 10 mg/L khfii bl tdng td ra cd uu diim hon so vdi cac logi vgt lilu khic nhu vd ngheu. vd sd cd hiiu qud xu ly dam ammonium la 90,83%, dgm nitrate li 64,03%
(Biii Tnrong Tfag, 2008).
3.2.2 Hiiu qud xd ly ldn
Hinh 7 thi hien him lugng cic dgng lin bao gdra ion POj^, tdng ldn hda tan (TDP) vi tfing lan (TP) qua cic giai doan xir ly cua he thfing thi nghiem. Hinh 7 cho thdy vdt lilu dit nung cd vai fro quan frpng dl xir ly lan frong nudc thii, bi be tdng ciing ldm giim ndng dp cdc dgng ldn de ttiu, li do vi sinh vit da sii dung trong vile tdng hgp te bio. Hieu suit xii l>' ldn trung binfa ciia 2 dgt bd tri thi ngfailm khoing 82.1%. Qua qui trinh thyc nghiem vdt lieu td ra bin bi vi mil vdt ly. mic dQ thdi gian thyc nghiim keo dii nhilu tfadng nhung vat lieu van giir nguyen hinh dgng va b'ch thudc ban ddu, tu>- nhien can kiem tra lgi tinfa chdt na\ trudc khi ip dung vdo cdc bi xir ly Ion frong thuc tl.
Tap chi Khoa hgc Tnr&ng Dai hgc Cdn Tha Phdn .A - Khoa hgc Tir nhien. Cong nglie va Moi Inrang 28 (20!3/: 3S-46
4.5 - 4.0 - 3.5 - 3.0 2.5 • 2.0 1 5 I.O 0.5 •
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DTP DTDP ORP, • TP DTDP SRPI
Hinfa 7: Hdm lupng lan qua cdc giai doan xir ly cua he thong xu ly qua 2 dgt thi nghi|m Cac vdt li|u niy do tfaanh phin co chira khoang
chdt CO cdc ion sit va nhfim hoat dfing, cdc nhdm oxit tren bi mdt, hogc cac hpp chdt chiia canxi co the phdn iing vdi ion phot phit tgo ra cdc hop chdt kit tiia chiia phosphate vi de ding logi lin ra kfadi h | thdng. Herman Helness, 2007; Bilanovic, 1999, ngoii tic dung hap phu, cac vat lieu hap phu cdn CO vai trd la gia the cho cac vi sinh vat di dudng phit triln, trong dilu kiln thilu khi.
mpt sd vi sinh vdt di dudng, cd khi nang sii dyng carbon, nifrate va pfaosphate dl tich ty ndng lirgng (poly-p-hydroxy-alkanoates (PHA) va glycogen) cho tl bio CO the. Theo do, him lygng phosphate cd khuynh huong giam di dang kl so vdi ban ddu.
So sdnh gii tri cdc dang lan (P04^". TDP, va TP) giua cdc cdp HK vd DN, DN vi DNC, DNC vd BT cho thdy d cSp PiK-DN co sy sai khdc cd y nghT
thdng kl (p<0,05). Sau khi qua bl DN ham lupng lin giam manh nhu vay cho phep ta kit ludn bl ddt nung li noi xay ra phan iing loal PO4"' ra khfii nudc thii. Vd ham lugng PO4'", TDP va TP deu nam frong khoing cho phep cua lieu chuan chat lugng thii cdng r ^ i l p chl biln thuy san trudc khi thdi vdo cdc ngufin nudc dugc diing cho rayc dich cip nudc sinh hoat (QCVN11:2008/BTNMT, logi A) vi lilu chuin chit lugng nudc mat dung cfao myc dfch tudi tllu thiiy lgi (QCVN08:
2008/BTNMT,logiBl).
3.2.3 Bien dgng vi sinh trong hi thong xu ly dam. ldn
Kit qui khdo sit mat dp cic logi vi sinfa bao gdm tdng vi sinh vat di duong, coliform vi E. coli dugc frinh bay trong Hinh 8.
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if
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i
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Pol 2 D Heterotrophic b. D Colifomi D Ecoii Hinfa 8: Bien ddng mgt dp ciia vi sinfa vat qua cic giai dogn xir ly o* 2 dot thi nghiem
44
Tgp chi Khoa hgc Tnrang Dai hgc Cdn Tha Phan.4. Klioahgc Tir nliien. Cdng ngbe vd Moi tnr&ng 2S I20l3i. 38-46 Hinh 8 cho thiy dao dfing mat dp vi sinh vat di
dudng tang ldn lupt qua cac bi HK, DN, DNC va BT tir bi HK khoang 10^-10^ CFU/mL, mat dp vi sinh vat di duong tang lln khoang 100 lan dgt 10*- 10' CFU/mL d bi BT. Diiu nay cho thay mfii trudng tai bl khir nitrate phii hgp cho sy sinh truong ciia cac vi sinh vit di dudng vd sy tang sinfa ciia cac vi sinh vit di duong 6 giai doan ndy cd vai frd ddc bill quan frpng frong qud frinh khir nifrate ciia he thdng. Sy hien dien ciia vi sinh vit di duong niy khfing dang ngai bdi vi chung se ty giam di khi ngudn carbon ngimg cung cip (Metcalf va Eddy, 2003; Gabriel Bitton, 2003).
Mat sfi coliform dao dfing trong khodng 10^ - lO^CFU/raL, coliform dugc ghi nhgn Id tdn tai tfit trong he thfing vi dien biln mil dp coliform tirong ty nhu diln bien mat dp vi sinh vat di dudng nhimg thdp hon gan 10 lin
He thdng xir ly tdn tgi vi sinh vgt dj dudng vd coliform vdi mat dp kha cao luy nhiin chiing tfii ghi nfadn khfing cd sy ton tgi cua E. coli frong sufil hi thfing qua tit ca cdc dgt thi nghiera.
So sdnh mat sd vi sinh vdt di dudng giiia cac cdp HK va DN, DN va DNC. DNC va BT cho thiy d cip DNC-BT cd sy sai khac cd y nghTa (p<0,05) d ci hai dgt thf nghiem la do vi sinh vat di dudng di sii dung ngudn carbon vd ting mat sfi vi kit qua khio sdt tucmg ty dfii vdi chi lilu coliform.
4 KET LUAN VA DE XUAT 4.1 Kit luan
Cac khfii bl tfing la vdt lilu tdt de lam gia thi cho vi sinh vat bdm vi thyc hien phin iing khir nifrate.
HI thfing xu ly cin dugc bd sung ngudn carbon tir ben ngoai va sinh vgt cd the su dyng saccharose la ngufin cung cap carbon cho hogt dpng khir nifrate hda.
- Mat dp vi sinh vat di dufing va coliform d dau ra cdn cao dao dpng trong khoang 10^- 10' CFU/mL tuy nhien mat dp niy se giira khi qua frinh cung cip ngudn carbon kit thiic.
- Dat phen nung co khd ndng xir ly lin trong nudc thai dat hieu qua cao.
- Cac chi tiiu hda ly frong nudc ddu ra sau he thfing xii ly nhu pH. NOz'. NO?', P04-'- dat quy chuin chat lugng nudc mit dimg cho rayc dfch tudi tieu thiiy lgi (QCVN08:2008/BTNMT, loai Bl) va tieu chuin chdt lygng thai cdng nghiep chi bien thiiy san tnrde khi tiiai vao cac ngufin nudc
dugc dimg cho myc dich cap nudc sinh hogt (QCVNl 1:2008/BTNMT, logi A).
4.2 Dexuat
- Lip lgi nghiin eiiu vdi nfing dp dgm nifrate va tdc dp ddng khic nhau de tim ra hieu suit kfaii nitrate tfit nhit ciia he thong.
Nghiin cim cac vat lieu khac sin cd tgi dja phuong cd khd ndng loai bd ldn frong nude thai hieu qui hon.
TAI LIEU THAM KHAO
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Denitrification under high nifrate concenfrations and alternating anoxic conditions Water Res. 33, 3311-3320.
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