Phát triển kỹ thuật xử lý nước thải nuôi giống thủy sản bằng phương pháp màng sinh học nhằm tái sử dụng

Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Noi 10/2010<br /> <br /> <br /> <br /> P H A T TRIEN KY THUAT XLT LY NlT^C T H A I NUOI GIONG THUY<br /> SAN BANG PHLTONG P H A P M A N G SINH HOC N H A M T A I SlT DUNG<br /> <br /> Pham Thi Hong Du-c, Le Van Cat<br /> Vien Hoa hpc<br /> 18 - Dudng Hoang Quoc Viet, Cau Giay, Ha Noi<br /> Email: hongduc ph(a),vahoo.com.vn<br /> Tom tat:<br /> Trin the gidi cd rdt nhiiu logi cdng nghi sinh hpc dd dupe sir dung trong cdc he<br /> thdng tdi sic dung nude nudi trdng thuy sdn nhu: dia query sinh hpc, Ipc nhd gipt, Ipc<br /> ngap nude, Ipc ndi, mdng Ipc tdng cd dinh vd mdng Ipc sinh hpc tdng chuyin ddng...<br /> Hiiu qud ciia qud trinh cd thi duac ddnh gid thdng qua qud trinh nitrat da vd khic<br /> nitrat boi vi amdni la ddc chdt cho cdc lodi thiiy sinh d ndng dd rdt thdp.<br /> Nitrat hda vd khic nitrat bao gdm cdc qud trinh vdt ly, hda hpc vd sinh hpc, cdc<br /> qud trinh dd bi dnh hudng bdi rdt nhieu cdc yiu td khdc nhau: ndng dd ca chdt vd<br /> oxy hda tan, su cd mat chdt hieu ca, nhid dp, pH dd kiim vd dd due...Nghiin cieu<br /> dnh hudng cita cdc yiu td dd len ddng hpc qud trinh nitrat hda se giiip ta cd thi<br /> tien doan duac hiiu qud cua hi Ipc sinh hpc. Hieu biit mdt cdch thdu ddo vi ddng<br /> hpc qud trinh do se giup ich rdt nhiiu cho viec thiit ki vd van hdnh cdc hi Ipc<br /> sinh hpc.<br /> Bdi bdo ndy xin trinh bdy mdt cdch nhin tdng quan vi qud trinh logi bd nita<br /> xdy ra trong hi Ipc sinh hpc vd dua ra mdt sd kit qud nghien ciru cho phep tiin<br /> dodn tdc dd ciing nhu hieu qud phdn ung giiip ich cho cdng viec thiit ki vd van<br /> hdnh cdc hi xie ly sinh hpc trong nhieng dieu kiin cu thi nhdm muc dich tdi sic<br /> dung nude nudi gidng thiiy sdn.<br /> Abstract:<br /> Various types of biotechnology have been used in recirculating aquaculture<br /> system (RAS) under different water quality and operating conditions like fixed<br /> film biofilter, rotating biological contactor, trickling filtration, submurged<br /> filtration, floating filtration, moving biofilm bed reactor...<br /> The effectiveness of the process can be evaluated by nitrification and<br /> denitrification efficiency because ammonia is the toxic for aquatic animal species<br /> with the very low concentration.<br /> Nitrification involves physical, chemical and biological processes, that are<br /> governed by a variety of parameters: substrate and dissolved oxygen<br /> concentrations, organic matters, temperature, pH, alkalinity and turbidity. The<br /> impacts of these parameters upon nitrification kinetics help predicting the<br /> performance of a biofilter for a given application. Knowledges on the kinetical<br /> behaviours of the process will help to design and operate a biofilter.<br /> This paper presents the overview of removing nitrogen process occurring in<br /> biofilter system and some results allowing the prediction of the reaction rate and<br /> <br /> <br /> 187<br /> Tiiu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7<br /> <br /> <br /> reaction yield with rather high accuracy, thus helping the design and operation of<br /> a biofilter under practical conditions for purpose recirculating aquaculture<br /> system.<br /> <br /> <br /> 1. VAN DE MOI TRU^OfNG TRONG NUOI TRONG THUY S A N<br /> Nuoi trong thuy san la mot trong nhirng nganh phat trien mang lai ngudn thu nhap kinh te<br /> ldn dong gop dang kl vao su phat triln kinh tl cua Viet Nam. Hinh thiic nudi trong thuy san<br /> lien quan din miic dp d nhiem hay phu thuoc nguon nude nuoi gom: nudi thuong pham va<br /> nuoi gilng. D I chu dong dugc viec nuoi trIng thuy san trudc bet phai chu dgng dugc nguon<br /> giong bang each tu uong nuoi con giong va kiem soat dugc moi trudng nudi.<br /> 6 nhilm moi trudng nude trudc tien bi tac dgng bdi miic do sii dung thiic an: moi trudng<br /> it bi anh hudng khi nuoi d dang quang canh hoac ban tham canh, bi anh hudng nang ne hon<br /> trong phuong thiic nuoi tham canh ke ca nuoi thuong pham lan nuoi giong.<br /> De dat dugc nang suat cao can sir dung mgt lugng rat ldn thiic an tdng hgp chiia ham<br /> lupng dinh dudng cao (30-40 % protein tho) cung cap cho vat nudi. Thiic an dugc vat nuoi<br /> tieu thu chuyen thanh sinh khoi va cac chat thai nhu phan, chat bai tiet. Trong khi do vat nuoi<br /> chi hap thu dugc 20 - 50% lupng dam, 16 - 65% phot pho, 20 - 30 % carbon tir nguon thiic<br /> an de tao thanh sinh khoi [1].<br /> Chat thai va lugng thiic an du thira bi phan buy trong moi trudng nuoi thanh cac doc to<br /> nhu: amoni, chat hiru ca dang de sinh huy, nitrit, nitrat, hydro sunfua...; chiing quay lai tac<br /> dong true tiep len vat nuoi va tac dong co hai tdi moi trudng nudi (vi du nhu hien tupng phu<br /> dudng). Mat dp vat nuoi cao, lugng thiic an sir dung ldn dan den he qua tat yeu la moi trudng<br /> nuoi bi 6 nhiem nang ne.<br /> De duy tri chat lupng moi trudng nuoi, phuong thiic truyen thong thudng sir dung tai Viet<br /> nam la thay nude theo mot chu ky nao d6.<br /> Nude thai tir cac ao nuoi khi do vao cac thuy vuc nhan nude se gay ra hien tugng phii<br /> dudng, boi lang, gay dich benh cho cac loai song hoang da va dac biet nguy hilm la chiing<br /> gay ra dot bien gien cho vi sinh vat khi nude thai chiia cac chat khang sinh.<br /> it hay khong thai ra moi trudng, hoac thai ra moi trudng van dam bao an toan cho moi<br /> trudng nude nhan la van de khong the tranh khoi khi sir dung phuang phap nuoi tham canh.<br /> Bien phap tot nhat va ciing la kho thuc hien nhat la tai sir dung nude nudi vao diing muc dich<br /> nuoi thong qua cac giai phap xir ly thich hgp.<br /> Mdt sl nude phat trien dang cl gang hudng tdi phat triln nudi trdng thuy san bin viing<br /> bang each xac lap dugc nganh san xuat khong (it) co nude thai.<br /> K I tir khoang 30 nam trd lai day (dau nhirng nam 80 cua thi ky 20). Phuang thiic nuoi<br /> thuy san sir dung nude tuan hoan ( Recirculating Aqualculture System - RAS) da phat triln<br /> va trd nen kha quen thudc d mgt so noi, nhat la d cac nude phat triln.<br /> Dli tugng cin xir ly trong moi trudng nuoi thuy san gdm: hgp chit nita (chu ylu la<br /> amoni), hgp chat phdt pho, chat hiiu co tan, can khong tan (chu ylu la thanh phin chit him<br /> co) va khi carbonic (trong trudng hgp tai sir dung nude). Trong cac tap chit tren thi thanh<br /> phan dang quan tam nhat la amoni.<br /> <br /> <br /> <br /> <br /> 188<br />  Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Noi 10/2010<br /> <br /> Xir ly amoni co the thuc hien bang nhieu phuang phap boa hgc, vat ly va sinh hpc.<br /> Nhung chi co phuong phap sinh hpc la phuong phap co hieu qua cao than thien vdi moi<br /> trudng, khong gay doc hay tac dung phu cho loai nuoi.<br /> Trong phuong phap sinh hpc co rat nhieu cac cong nghe xir ly khac nhau, co the sir dung:<br /> vi sinh vat, tham thuy thuc vat, hay to hpp cac tham thuy thuc vat vdi vi sinh.<br /> Tuy thuoc vao quy mo va hinh thiic nuoi trong ma ta sir dung cac cong nghe cho hgp ly.<br /> Vdi hinh thiic nuoi thuong pham c6 quy mo dien tich nuoi trong ldn, khi do sir dung cac<br /> tham thuy thuc vat hay cong nghe to hgp la thich hgp nhat. Nhung vdi hinh thiic nuoi giong<br /> thong thudng quy mo nuoi trong la nho, nguon 6 nhiem bien dgng ldn va doi hoi mirc dp lam<br /> sach sau thi sir dung cong nghe vi sinh la hgp ly nhat.<br /> Do toe do phat trien cham cua vi sinh Nitrosomonas thi cac ky thuat xir ly phai ap dung la<br /> phuong phap mang vi sinh: cot lgc sinh hgc (tang tinh), lgc nho gigt, dia quay sinh hgc, tang<br /> luu the, tang chuyen dgng. So sanh hieu qua xir ly cua cac ky thuat tren, hieu qua ciia ky<br /> thuat tang luu the la cao nhat; ky thuat tang chuyen dong va ky thuat tang tinh (cot Ipc sinh<br /> hpc) ciing dat hieu qua cao dong thdi phuong thiic van hanh don gian hon nhieu so vdi tang<br /> luu the. Vi vay no to ra thich hgp doi vdi muc dich tai sir dung nude thai trong cac trai nuoi<br /> giong CO quy mo san xuat nho.<br /> Ngoai ra Igi dung dac diem cua vi sinh di dudng, co toe do phat trien gap bon lan toe do<br /> phat trien cua vi sinh tu dudng. Tan dung uu diem do co the ap dung cho cac viing san xuat<br /> ldn bang each thiic day sir phat trien cua vi sinh vat di dudng trong moi trudng nude nuoi.<br /> Khi vi sinh di dudng phat trien, chiing se sir dung thanh phan chat hiiu co va amoni trong<br /> nguon nude de tao sinh khoi. Sinh khoi tao thanh co the sir dung lam thiic an tai cho cho vat<br /> nuoi hoac cho cac loai dgng vat phii du (la thiic an cho vat nudi).<br /> De thiic day vi sinh phat trien ngudi ta co the "cay" vi sinh vao nguon nude nuoi thong<br /> qua cac che pham vi sinh thich hgp.<br /> Trong thuc te, phuang an xir li tren chua mang lai dugc hieu qua nhu mong dgi do kho<br /> khan ve kiem soat mat do vi sinh trong moi trudng nuoi trong thuy san.<br /> <br /> <br /> 2. MOT SO KY THUAT MANG SINH HOC DE XU' LY NU^OC THAI NUOI GIONG<br /> THUY SAN CO HIEU QUA CAO<br /> De xir ly nude thai nuoi giong thuy san nham muc dich tai sir dung thi ky thuat mang Ipc<br /> sinh hpc la thich hgp nhat vi no to ra:<br /> - Co bieu qua xir ly cao nhd tap trung dugc mat dp vi sinh ldn, co tinh chpn cao vao<br /> trong chat mang.<br /> Co tinh on dinh cao nhd cd Idp mang bao ve.<br /> - Linh boat, de kiem soat, de thich nghi va phii hgp vdi nhieu dieu kien.<br /> - Cac ky thuat mang sinh hgc ap dung cho xir ly nude nuoi giong thuy san gom:<br /> - Ky thuat mang lgc sinh hgc tang tinh (cot lgc sinh hgc).<br /> - Ky thuat mang lgc sinh hgc tang chuyen dong (MBBR).<br /> Ca hai ky thuat tren deu sir dung chat mang lam cho tni an cho vi sinh va tap trung chiing<br /> vi sinh thich hgp cho muc tieu xir ly. Trong hai ky thuat tren deu c6 nhiing uu diem rieng.<br /> <br /> <br /> 189<br /> Tieu ban: Moi tru&ng vd Ndng hcgng ISBN: 978-604-913-013-7<br /> <br /> <br /> Khi sir dung mang lgc sinh hpc ting chuyin dgng nhd co qua trinh chuyen khoi nen hieu<br /> qua cua qua trinh oxi boa amoni (nitrat hoa) cao, nhung ngugc lai hieu qua khii chi dat<br /> khoang tren dudi 30%. Tiic tic do chuyin hoa amoni thanh nitrat se nhanh va chi ban cbl<br /> lugng nitrat tich liiy trong moi trudng nuoi khong dang ke.<br /> Trong khi do nlu sir dung ky thuat mang lgc sinh hgc ting tinh (cot lgc sinh hgc) thi hieu qua<br /> nitrat boa khong cao lim do bi ban cbl qua tririh chuyin khoi, nhung hieu qua khir nitrat co the<br /> dat din 90% tham chi cao han, giai quylt vin dl nitrat hoa bi tich luy tuong dli triet de.<br /> <br /> <br /> 3. MOT SO KET QUA NGHIEN CLTU TAI VIEN HOA HOC<br /> Tiln hanh nghien ciiu xir ly nude nuoi thuy san mau tu pha theo hai cong nghe chgn Ipc<br /> (cong nghe mang vi sinh ting chuyin dong - MBBR va cot Ipc sinh hpc) c6 cac uu diem noi<br /> trpi nhu da trinh bay d tren thich hgp cho viec xii ly loai binh nude thai nay.<br /> 3.1 Ky thuat mang vi sinh tang chuyen dong -MBBR.<br /> Sir dung ky thuat mang vi sinh ting chuyin dgng (MBBR) tien hanh theo ky thuat dong lien<br /> tuc dl danh gia hieu qua xir ly tren mau mo phong va nhan dugc mgt so ket qua nhu sau:<br /> Miu mo phong co do man lin lugt la 10%o, 20%o va 30%o, nIng do amoni cua nude<br /> nguln la 5mg NH4"^-N/1 va duy tri nIng do sau khi xir ly nhd ban 0,2mg NH4"^-N/1, miic dp<br /> tich liiy nitrit (ciing la ddc tl dli vdi dong vat thuy sinh) tuong ling vdi tieu chuan nude nuoi<br /> thuy san cua thi gidi. Hieu suat oxi boa amoni (%Hoxh NH4+) va khir nito tdng (%)Hkh TN) phu<br /> thuoc vao dp man va thdi gian luu dugc trinh bay trong bang sau:<br /> Bdng 1: Anh hudmg ciia dd mudi lin hiiu sudt oxi hda amdni vd khir nita tdng khi sir dung ky<br /> thudt MBBR<br /> <br /> Q(i) 15,9 14,0 13,3 11,4 10,3 9,0 7,3 5,1 3,4<br /> <br /> tvlm (h) 0,113 0,128 0,135 0,158 0,175 0,200 0,246 0,353 0,529<br /> <br /> %HoxhNH4+ 70 80 86 90 94 95 97 98 98<br /> 30%°<br /> %HkhT N 15 18 22 24 26 27 28 30 32<br /> <br /> %Hoxh NH4+ 71 82 87 91 95 96 97 98 98<br /> 20%°<br /> %Hkh TN 15 19 23 25 27 28 29 31 32<br /> <br /> %Hoxh NH4+ 72 83 89 92 96 97 98 98 98<br /> 10%°<br /> %)Hkh TN 15 20 23 25 27 28 29 31 32<br /> <br /> Mat do vat lieu mang sir dung (ty le the tich giira vat lieu mang va the tich thiit bi hieu<br /> dung xii ly) trong ky thuat tang vi sinh chuyen dgng nam trong khoang 20%).<br /> 3.2 Ky thuat mang vi sinh tang co dinh - cot loc sinh hoc<br /> Sir dung ky thuat cot lgc sinh hgc vdi phan tram vat lieu mang chilm 60%) thi tich bl<br /> phan ling. Danh gia hieu qua xir ly tren mlu mo phong va mau thuc chiing toi da nhan dugc<br /> mot so ket qua nhu sau:<br /> <br /> 190<br />  Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Not 10/2010<br /> <br /> <br /> Mau mo phong co dp man la 10%o, 20%o va 30%o, nong dp amoni ciia nude nguon la 5mg<br /> NH4'^- N/1 va duy tri nong do sau khi xir ly nho ban 0,2mg NH4'^-N/1, miic do tich luy nitrit<br /> (cung la dgc to doi vdi dgng vat thiiy sinh) tuong img vdi tieu chuan nude nuoi thuy san cua<br /> the gidi [5, 6]. Hieu suat oxi boa amoni (%Hoxh NH4+) va khir nito tong (%Hkh TN) phu thuoc<br /> vao do man va thdi gian luu dugc trinh bay trong bang sau:<br /> Bdng 2: Anh hudng cua dp mudi len hiiu sudt oxi hda amdni vd khic nita tdng khi sic<br /> dung ky thudt cdt Ipc sinh hpc<br /> <br /> Q(l) 15,9 14,0 13,3 11,4 10,3 9,0 7,3 5,1 3,4<br /> tvlm (b) 0,63 0,71 0,75 0,88 0,97 1,11 1,37 1,96 2,94<br /> <br /> %Hoxh NH4+ 88 95 96 96 97 97 96 97 98<br /> 30%°<br /> %HkhT N 65 68 72 76 82 85 90 94 95<br /> <br /> %Hoxh NH4+ 91 97 97 96 96 98 96 97 99<br /> 20%°<br /> %Hkh TN 75 80 84 88 90 91 93 95 97<br /> <br /> %Hoxh NH4+ 92 96 96 97 97 97 98 98 98<br /> 10%°<br /> %Hkh TN 82 84 86 90 92 94 95 96 97<br /> <br /> Nhin vao hai bang ket qua cho ta thay khi van hanh d cung mot luu lugng thi thdi gian<br /> luu (tinh theo vat lieu mang - tvim) ciia ky thuat mang vi sinh tang chuyen dgng nho hon rat<br /> nhieu so vdi ky thuat cot lgc sinh hgc nguyen nhan do phan tram vat lieu mang sir dung it<br /> ban (nghTa la dd ton vat lieu ban) ma hieu qua oxi boa amoni tuong doi cao nhung hieu qua<br /> khir tong nito thap.<br /> Trong ky thuat MBBR hieu qua khir tong nito chi dat toi da 32% trong khi do sir dung ky<br /> thuat cot Ipc sinh hpc hieu qua khir c6 the dat 97% (gan nhu hoan toan loai bo nito tranh su<br /> tich IQy nito khi quay vong tai sir dung nguon nude do).<br /> Sir dung ky thuat MBBR can thiet bi phan iimg co kich thudc ldn vi lugng vat lieu mang<br /> chi cho phep chiem 20% the tich de duy tri miic do chuyen dgng hon loan trong d6. Con neu<br /> sir dung ky thuat cot lgc sinh hgc thi se tiet kiem dugc thiet bi phan ling vi vat lieu mang<br /> chiem 60% tham chi co the len 70% the tich cua be.<br /> Nhu vay moi ky thuat deu co nhiing uu diem rieng, nen tuy thuoc vao muc tieu can oxi h6a<br /> amoni hay dong thdi ca oxi boa amoni va khir nita ma ta lira chgn cong nghe cho thich hgp cho<br /> hoan canh kinh te va dac thu san xuat trong cac trai nuoi giong thuy san doi hoi cac tieu chi:<br /> - Hieu qua xir ly cao (luu lugng xir ly ldn tren mot don vi cong suat thiet bi).<br /> Van hanh don gian va chi phi thap;<br /> Thich ling vdi san xuat mang tinh thdi vu;<br /> Thich hgp cho qui mo san xuat nho;<br /> De nhan rgng va trien khai ngoai thuc te;<br /> Phan ldn vat lieu va thiet bi lien quan den cong nghe tang vi sinh chuyen dgng deu de tim<br /> kiem, san xuat trong nude.<br /> <br /> <br /> 191<br /> Tiiu ban: Moi iru&ng vd Ndng lugng ISBN: 978-604-913-013-7<br /> <br /> <br /> <br /> <br /> 4. DE XUAT VA KET LUAN<br /> Moi trudng nude nuoi thuy san la mgt trong nhirng yeu to quyet dinh sir thanh cong hay<br /> that bai cua nganh nuoi trong thuy san, dac biet theo phuang thiic nudi tham canh.<br /> 6 nhiem moi trudng nude nuoi chu ylu bat nguon tir nguon thiic an cap cho vat nuoi.<br /> Thiic an khong dugc vat nuoi hip thu tham gia vao cac qua trinh chuyen boa boa hgc,<br /> sinh boa, quang hoa trong he sinh thai nuoi, tao ra mdi trudng khdng thich hgp doi vdi<br /> vat nudi.<br /> Bien phap thay nude de duy tri moi trudng nuoi ve tong the la bat hgp li, khd chap nhan<br /> ve phuang dien phat trien ben vimg cua nganh san xuat. Nuoi trdng thuy san khong co<br /> nude thai tiic la tai sir dung nude nuoi hay san xuat khep kin la xu hudng tat yeu va dang<br /> dugc cac nude co nganh nuoi thuy san phat trien phan dau thuc hien.<br /> Giai phap xir li mdi trudng va tai sir dung nude nuoi cd the thuc hien theo ky thuat: cot<br /> lgc sinh hgc hay ky thuat mang vi sinh tang chuyen dgng tiiy thuoc vao muc tieu dat ra.<br /> Pham vi ap dung va hieu qua phu thuoc vao dieu kien hien hiru cua timg noi san xuat.<br /> <br /> <br /> TAI LIEU THAM KHAO<br /> 1. J. E. Bardach (Ed.), "Sustainable aquaculture John Willey Sons...", Aquaculture<br /> engineering, Vol.34 (2006)<br /> 2. J.G. Ferreira a, et al, "Analysis of coastal and offshore aquaculture: Application of<br /> the FARM model to multiple systems and shellfish species ", Aquaculture 289(2009),<br /> 32-41.<br /> 3. T. Gomiero, et al, "^zW/vew/fy use and technical performance of freshwater fish<br /> aquaculture in different socioeconomic contexts: China and Italy", Agriculture,<br /> Ecosystems and Environment 62 (1997), 169-185.<br /> 4. J. Matos, et al, "Experimental inte aquaculture offish and red seaweeds in Northern<br /> Portugal", Aquaculture 252 (2006), 31-42<br /> 5. O. Schneider, et al, "Analysis of nutrient flows in integrated intensive aquaculture<br /> systems", Aquaeultural Engineering 32(2005), 379-401.<br /> 6. M. B. Thomas, J. M. Ebeling, F.W. Wheaton, S. T. Summerfelt, "Recirculating<br /> aquaculture system ", NRAC Publication No. 01-002<br /> <br /> <br /> <br /> <br /> 192<br />