Recirculating aquaculture systems (RAS) tau dhau los ua ib qho tseem ceeb ntawm txoj kev loj hlob nyob rau hauv niaj hnub aquaculture, muab qhov zoo ntawm kev txuag dej, ruaj khov, thiab txo qis ib puag ncig. Txawm li cas los xij, cov tshuab no tsim cov dej khib nyiab uas muaj cov khoom siv tshem tawm, nitrogen- thiab phosphorus-raws li cov pa phem, thiab ntau cov organic yaj. Yog tias cov dej khib nyiab no nkag mus rau hauv nanofiltration (NF) system yam tsis muaj pretreatment kom raug, cov membrane fouling hnyav yuav tshwm sim, txo cov flux sai thiab nce nqi ua haujlwm. Vim li no, xaiv cov cuab yeej ua ntej ua kom zoo yog qhov tseem ceeb rau kev tswj xyuas kev ruaj ntseg ntawm NF kev ua haujlwm.
Cov kev tshawb fawb tsis ntev los no tau muab piv rau ob lub thev naus laus zis ua ntej tseem ceeb -flocculation thiab ultrafiltration- los tshuaj xyuas lawv cov kev ua haujlwm tshem tawm cov pa phem, cuam tshuam rau NF flux poob qis, thiab cov yam ntxwv ntawm daim nyias nyias fouling. Cov kev tshawb pom muab cov lus qhia tseem ceeb rau kev xaiv cov txheej txheem pretreatment tsim nyog hauv RAS kev kho dej khib nyiab.
Hauv flocculation pretreatment, sodium alginate tau pom qhov ua tau zoo tshaj plaws ntawm peb qhov kev sim flocculants. Ntawm qhov kev pom zoo ntawm 45 mg / L thiab qhov nrawm nrawm ntawm 1200 r / min, nws ua tiav qhov siab tshaj plaws tshem tawm cov khib nyiab ntawm 79.70%. Txawm li cas los xij, kev tshem tawm kev ua haujlwm rau ammonia nitrogen, nitrate, nitrite, thiab sulfides feem ntau qis dua 40%, qhia tias flocculation tsis txaus rau cov kuab paug uas feem ntau pom nyob rau hauv aquaculture tailwater. Txoj kev tshawb no kuj pom tias sodium alginate tsim me me, compact flocs uas nyiam tso rau ntawm NF daim nyias nyias, tsim kom muaj txheej txheej ncuav mog qab zib. Vim nws cov qauv polysaccharide ntuj, sodium alginate kuj muab lub substrate rau microbial kev loj hlob nyob rau hauv lub sij hawm ncua sij hawm, uas ua rau kom lom fouling ntawm NF daim nyias nyias. Yog li ntawd, lub flux rov qab tom qab ntxuav yog qhov tsis zoo, qhia tias fouling tshwm sim los ntawm flocculation yog ntau nplaum thiab nyuaj rau tshem tawm.
Nyob rau hauv sib piv, ultrafiltration (UF) daim nyias nyias, nrog pore qhov ntau thiab tsawg ntawm 0.01-0.1 μm, ua kom pom kev ua tau zoo hauv kev tshem tawm cov khib nyiab, ua tiav qhov kev tshem tawm siab txog 98.54%. Txawm hais tias UF muaj peev xwm txwv tsis pub tshem tawm nitrogen thiab phosphorus cov pa phem, nws txo qis cov khoom hnyav nkag mus rau NF system. Raws li qhov tshwm sim, NF daim nyias nyias tsim cov ncuav mog qab zib looser thaum lub sijhawm ua haujlwm, txo qhov pore blockage thiab ua kom qeeb ntawm qhov nce ntawm transmembrane siab. Raws li NF kev ntsuas kev ua tau zoo, cov dej khib nyiab pretreated nrog UF pom cov flux ntau dua, cov flux qeeb qeeb, thiab zoo dua flux rov qab zoo dua tom qab ntxuav dua piv nrog flocculation-pretreated dej. Qhov no qhia tau hais tias UF tuaj yeem ncua sijhawm tsis tuaj yeem rov qab fouling ntawm NF daim nyias nyias.
Kev tshuaj xyuas ntxiv uas siv excitation-emission matrix (EEM) fluorescence tau pom tias cov tshuaj ntxuav ntawm flocculation-NF system muaj cov peaks muaj zog uas sawv cev rau cov kua dej microbial byproducts, thaum cov peaks no yuav luag tsis muaj nyob hauv UF-NF system. Qhov no tau lees paub tias ncua kev daws teeb meem thiab cov xwm txheej ntawm polysaccharide ntawm sodium alginate txhawb kev loj hlob ntawm microbial, yog li ua rau cov membrane fouling hauv NF theem.
Zuag qhia tag nrho, qhov kev sib piv kom meej meej qhia tau hais tias ultrafiltration yog zoo dua flocculation raws li ib tug pretreatment txoj kev rau nanofiltration ntawm recirculating aquaculture dej khib nyiab. Txawm hais tias flocculation muab qhov kev xaiv qis tshaj - tus nqi rau kev tshem tawm thawj zaug, nws cov yam ntxwv ntawm floc thiab microbial txaus ntshai ua rau muaj kev cuam tshuam tsis zoo ntawm daim nyias nyias fouling. Yog li, UF + NF cov txheej txheem sib xyaw ua ke yuav tsum dhau los ua cov thev naus laus zis tseem ceeb rau kev kho thiab rov siv RAS cov dej khib nyiab.
Saib tom ntej, raws li kev tsim cov thoob dej yug ntses nce thiab cov kev cai ib puag ncig tau nruj dua, cov ncauj lus xws li nanofiltration fouling tswj, ultrafiltration pretreatment optimization, thiab kev loj hlob ntawm qis - siab siab -efficiency NF daim nyias nyias yuav tau txais kev saib xyuas ntxiv. Kev koom ua ke UF thiab NF rau hauv kev sib cog lus thiab lub zog ntau dua -cov tshuab ua haujlwm tau zoo yuav txhawb nqa kev hloov pauv ntawm cov dej khib nyiab hauv dej rau kev rov qab los, txo cov paug tawm, thiab kev tswj dej kom ruaj khov dua.
