Maita basa nekushanyira nature.com. Shanduro yebrowser yauri kushandisa ine rutsigiro rushoma rweCSS. Kuti uwane ruzivo rwakanaka, tinokurudzira kuti ushandise vhezheni yebrowser yazvino (kana kudzima compatibility mode muInternet Explorer). Pamusoro pezvo, kuti uve nechokwadi chekuti rutsigiro runoramba ruchienderera mberi, saiti iyi haizosanganisire masitayiri kana JavaScript.
Dutu reguruva rinotyisa zvikuru kunyika dzakawanda pasi rose nekuda kwekukanganisa kwaro kurima, hutano hwevanhu, network dzekufambisa uye zvivakwa. Nekuda kweizvozvo, kukanganiswa kwemhepo kunoonekwa sedambudziko repasi rose. Imwe yenzira dzisingakuvadzi nharaunda dzekudzivirira kukanganiswa kwemhepo ndeyekushandisa microbial induced carbonate precipitation (MICP). Zvisinei, zvigadzirwa zveMICP inokonzerwa nekuora kweurea, zvakaita seammonia, hazvina kunaka kana zvichigadzirwa zvakawanda. Chidzidzo ichi chinopa maformula maviri e calcium formate bacteria ekuparadza MICP pasina kugadzira urea uye chinoenzanisa zvizere mashandiro avo nemafomula maviri e non-ammonia-producing calcium acetate bacteria. Mabhakitiriya anofungidzirwa ndiBacillus subtilis naBacillus amyloliquefaciens. Kutanga, kukosha kwakagadziridzwa kwezvinhu zvinodzora kuumbwa kweCaCO3 kwakaongororwa. Miedzo yemhepo yakazoitwa pamasampuli ejecha akarapwa nemafomula akagadziridzwa, uye kuramba kukanganiswa kwemhepo, stripping threshold velocity, uye kuramba kurwiswa kwejecha zvakayerwa. Ma allomorph eCalcium carbonate (CaCO3) akaongororwa achishandisa optical microscopy, scanning electron microscopy (SEM), uye X-ray diffraction analysis. Ma formulations akavakirwa paCalcium formate akaita zvirinani kupfuura ma formulations akavakirwa paAcetate maererano nekuumbwa kwecalcium carbonate. Pamusoro pezvo, B. subtilis yakagadzira calcium carbonate yakawanda kupfuura B. amyloliquefaciens. SEM micrographs dzakaratidza zvakajeka kubatana uye kudhindwa kwemabhakitiriya anoshanda uye asingashande pacalcium carbonate kunokonzerwa nekudonha kwemvura. Ma formula ese akaderedza zvakanyanya kukurwa kwemhepo.
Kukukurwa kwemhepo kwagara kuchizivikanwa sedambudziko guru rinotarisana nenzvimbo dzakaoma uye dzisina mvura yakawanda dzakadai sekuchamhembe kwakadziva kumadokero kweUnited States, kumadokero kweChina, Saharan Africa, nenzvimbo zhinji dzeMiddle East1. Kusanaya kwemvura munzvimbo dzakaoma uye dzisina mvura yakawanda kwakashandura nzvimbo huru dzenzvimbo idzi kuita magwenga, madutu ejecha, nenzvimbo dzisina kurimwa. Kuramba kuchikukurwa kwemhepo kunokonzera njodzi kunharaunda dzakadai senzvimbo dzekufambisa, ivhu rekurima, nenyika dzemaindasitiri, zvichikonzera mamiriro ekugara asina kunaka uye mitengo yakakwira yekukura kwemaguta munzvimbo idzi2,3,4. Chinokosha ndechekuti, kukurwa kwemhepo hakungokanganisi nzvimbo kwainoitika chete, asiwo kunokonzera matambudziko ehutano nehupfumi munharaunda dziri kure sezvo kuchitakura zvidimbu nemhepo kunzvimbo dziri kure nekwainobva5,6.
Kudzora kukanganiswa kwemhepo kuchiri dambudziko repasi rose. Nzira dzakasiyana-siyana dzekugadzirisa ivhu dzinoshandiswa kudzora kukanganiswa kwemhepo. Nzira idzi dzinosanganisira zvinhu zvakaita sekushandisa mvura7, mafuta mulch8, biopolymers5, microbial induced carbonate precipitation (MICP)9,10,11,12 uye enzyme induced carbonate precipitation (EICP)1. Kunyorovesa ivhu inzira yakajairika yekudzora guruva mumunda. Zvisinei, kukurumidza kwayo kupwanya mvura kunoita kuti nzira iyi isashande zvakanaka munzvimbo dzakaoma uye dzisina mvura yakawanda1. Kushandisa mafuta mulching compounds kunowedzera kubatana kwejecha uye kukweshana kwepakati pezvikamu. Hunhu hwavo hwakabatana hunobatanidza tsanga dzejecha pamwe chete; zvisinei, mafuta mulch anokonzerawo mamwe matambudziko; ruvara rwawo rwakasviba runowedzera kunwa kupisa uye runotungamira kurufu rwezvirimwa netupukanana. Kunhuhwirira kwavo nehutsi zvinogona kukonzera matambudziko ekufema, uye zvakanyanya kukosha, mutengo wavo wepamusoro chimwe chipingamupinyi. Biopolymers ndeimwe yenzira dzichangobva kukurudzirwa dzekuderedza kukanganiswa kwemhepo; dzinotorwa kubva muzvisikwa zvakaita sezvirimwa, mhuka nemabhakitiriya. Xanthan gum, guar gum, chitosan uye gellan gum ndidzo biopolymers dzinonyanya kushandiswa mukushandiswa kweinjiniya5. Zvisinei, ma biopolymer anonyungudika mumvura anogona kurasikirwa nesimba uye kubuda muvhu kana akasangana nemvura13,14. EICP yakaratidzwa senzira inoshanda yekudzora guruva pakushandiswa kwakasiyana-siyana kunosanganisira migwagwa isina kugadzirwa, madziva emumatsime nenzvimbo dzekuvaka. Kunyangwe mhedzisiro yayo ichikurudzira, zvimwe zvinokanganisa zvinogona kufungwa nezvazvo, zvakaita semutengo uye kushomeka kwenzvimbo dze nucleation (izvo zvinokurumidzisa kuumbwa nekunaya kwemvura kweCaCO3 crystals15,16).
MICP yakatanga kutsanangurwa mukupera kwezana remakore rechi19 naMurray naIrwin (1890) naSteinmann (1901) mukudzidza kwavo nezvekuora kweurea netupukanana twemugungwa17. MICP inzira yehupenyu inongoitika yega inosanganisira mabasa akasiyana-siyana etupukanana uye maitiro emakemikari umo calcium carbonate inokonzereswa nekuita kwemaion ecarbonate kubva kuma microbial metabolites ane calcium ions munharaunda18,19. MICP inosanganisira urea-degrading nitrogen cycle (urea-degrading MICP) ndiyo mhando inonyanya kuwanikwa ye microbial-induced carbonate precipitation, umo ureaase inogadzirwa nemabhakitiriya inokonzeresa hydrolysis ye urea20,21,22,23,24,25,26,27 seinotevera:
MuMICP ine chekuita nekutenderera kwecarbon oxidation yemunyu weorganic (MICP isina rudzi rwekuora kweurea), mabhakitiriya eheterotrophic anoshandisa munyu weorganic wakaita seacetate, lactate, citrate, succinate, oxalate, malate uye glyoxylate semasosi esimba kugadzira zvicherwa zvecarbonate28. Kana paine calcium lactate sesosi yecarbon uye calcium ions, maitiro emakemikari ekuumbwa kwecalcium carbonate anoratidzwa muequation (5).
Mukuita kweMICP, masero ebhakitiriya anopa nzvimbo dze nucleation dzakakosha zvikuru pakudonhedza calcium carbonate; pamusoro pemasero ebhakitiriya pane negative charge uye inogona kushanda semusanganiswa we divalent cations dzakadai se calcium ions. Nekudhonza calcium ions pamasero ebhakitiriya, kana huwandu hwe carbonate ion hwakwana, calcium cations uye carbonate anions zvinopindura uye calcium carbonate inowira pamusoro pebhakitiriya29,30. Maitiro acho anogona kupfupikiswa seizvi31,32:
Makristaro ecalcium carbonate anogadzirwa nebiogenerated anogona kukamurwa kuita mhando nhatu: calcite, vaterite, uye aragonite. Pakati pawo, calcite nevaterite ndiwo allomorphs ecalcium carbonate anonyanya kukonzerwa nemabhakitiriya33,34. Calcite ndiyo allomorphs yecalcium carbonate inogadzikana zvakanyanya muthermodynamically. Kunyangwe vaterite yakataurwa kuti inogona kuchinjika, inozopedzisira yashanduka kuita calcite36,37. Vaterite ndiyo yakanyanya kukora pamakristaro aya. Ikristaro ine hexagonal ine kugona kuzadza maburi zviri nani kupfuura mamwe makristaro ecalcium carbonate nekuda kwehukuru hwayo38. MICP yese iri miviri yakaora uye urea-undegraded inogona kutungamira mukudonha kwevaterite13,39,40,41.
Kunyangwe MICP yakaratidza mukana wekusimbisa ivhu rine matambudziko nevhu rinokonzerwa nemhepo42,43,44,45,46,47,48, chimwe chezvinhu zvinobva mu urea hydrolysis iammonia, iyo inogona kukonzera matambudziko ehutano akapfava kusvika akakomba zvichienderana nehuwandu hwekusvibiswa49. Mhedzisiro iyi inoita kuti kushandiswa kwetekinoroji iyi kuve negakava, kunyanya kana nzvimbo huru dzichida kurapwa, senge kudzvinyirira guruva. ​​Pamusoro pezvo, kunhuhwirira kweammonia hakutsungiririki kana maitiro acho achiitwa nemazinga ekushandiswa akakwira uye huwandu hwakawanda, izvo zvinogona kukanganisa kushanda kwayo. Kunyangwe zvidzidzo zvechangobva kuitika zvakaratidza kuti ammonium ions inogona kuderedzwa nekushandura kuita zvimwe zvigadzirwa zvakaita se struvite, nzira idzi hadzibvisi zvachose ammonium ions50. Nokudaro, pachine kudiwa kwekutsvaga dzimwe mhinduro dzisingagadzire ammonium ions. Kushandiswa kwenzira dzisina urea degradation dzeMICP kunogona kupa mhinduro inogona kunge isina kuongororwa zvakanaka mukuderedza kukanganiswa kwemhepo. Fattahi et al. vakaongorora kukanganiswa kweMICP isina urea vachishandisa calcium acetate neBacillus megaterium41, ukuwo Mohebbi nevamwe vakashandisa calcium acetate neBacillus amyloliquefaciens9. Zvisinei, chidzidzo chavo hachina kuenzaniswa nezvimwe zvinobva mucalcium uye mabhakitiriya asina calcium anogona pakupedzisira kuvandudza kurwiswa kwemhepo. Kunewo kushomeka kwezvinyorwa zvinoenzanisa nzira dzisina urea dzisina kuora nenzira dzeurea mukuderedza kukanganiswa kwemhepo.
Pamusoro pezvo, zvidzidzo zvakawanda zvekukukurwa kwevhu nemhepo uye kudzora guruva zvakaitwa pamienzaniso yevhu rine nzvimbo dzakati sandara.1,51,52,53 Zvisinei, nzvimbo dzakati sandara hadziwanzoitiki zvakanyanya pane makomo nenzvimbo dzakadzika. Ndokusaka madutu ejecha ari iwo anonyanya kuwanikwa munzvimbo dzerenje.
Kuti tikunde zvikanganiso zvataurwa pamusoro apa, chidzidzo ichi chaive nechinangwa chekuunza mhando itsva yemabhakitiriya asingaburitse ammonia. Pachinangwa ichi, takafunga nezvenzira dzeMICP dzinoderedza urea. Kushanda zvakanaka kwezvinobva mucalcium mbiri (calcium formate necalcium acetate) kwakaongororwa. Sekuziva kwevanyori, carbonate precipitation uchishandisa musanganiswa miviri yecalcium source nemabhakitiriya (kureva calcium formate-Bacillus subtilis necalcium formate-Bacillus amyloliquefaciens) hazvina kuongororwa muzvidzidzo zvekare. Sarudzo yemabhakitiriya aya yakavakirwa pamaenzyme aanogadzira anokonzera oxidation yecalcium formate necalcium acetate kuti igadzire microbial carbonate precipitation. Takagadzira chidzidzo chakakwana chekuedza kuti tiwane zvinhu zvakanaka zvakaita sepH, mhando dzemabhakitiriya necalcium sources uye kuwanda kwawo, chiyero chebhakitiriya kune calcium source solution uye nguva yekuporesa. Pakupedzisira, kushanda kweseti iyi yemabhakitiriya mukudzora kukanganiswa kwemhepo kuburikidza nekunaya kwecalcium carbonate kwakaongororwa nekuita bvunzo dzemhepo dzakatevedzana pamadundu ejecha kuti vaone hukuru hwekukanganiswa kwemhepo, kumhanya kwekutyoka kwejecha uye kuramba kwemhepo kurwisa jecha, uye kuyerwa kwepenetrometer uye zvidzidzo zve microstructural (semuenzaniso X-ray diffraction (XRD) analysis uye scanning electron microscopy (SEM)) zvakaitwawo.
Kugadzirwa kwecalcium carbonate kunoda ma calcium ions nema carbonate ions. Ma calcium ions anogona kuwanikwa kubva kumarudzi akasiyana-siyana e calcium akadai se calcium chloride, calcium hydroxide, uye skim milk powder54,55. Ma carbonate ions anogona kugadzirwa nenzira dzakasiyana-siyana dze microbial dzakadai se urea hydrolysis uye aerobic kana anaerobic oxidation ye organic matter56. Muchidzidzo ichi, ma carbonate ions akawanikwa kubva mu oxidation reaction ye formate ne acetate. Pamusoro pezvo, takashandisa calcium salts ye formate ne acetate kugadzira pure calcium carbonate, saka CO2 ne H2O chete ndizvo zvakawanikwa se by-products. Mukuita uku, chinhu chimwe chete chinoshanda se calcium source uye carbonate source, uye hapana ammonia inogadzirwa. Hunhu uhu hunoita kuti nzira yekugadzira calcium source uye carbonate ive yakanaka kwazvo.
Maitiro akafanana e calcium formate ne calcium acetate kugadzira calcium carbonate anoratidzwa mumafomula (7)-(14). Mafomula (7)-(11) anoratidza kuti calcium formate inonyungudika mumvura kugadzira formic acid kana formate. Saka mhinduro iyi ndiyo sosi ye calcium ne hydroxide ions dzakasununguka (mafomula 8 ne9). Nekuda kwe oxidation ye formic acid, maatomu ekabhoni ari mu formic acid anoshandurwa kuita carbon dioxide (fomula 10). Calcium carbonate inozogadzirwa pakupedzisira (mafomula 11 ne12).
Saizvozvowo, calcium carbonate inoumbwa kubva kucalcium acetate (equations 13–15), kunze kwekuti acetic acid kana acetate inoumbwa panzvimbo peformic acid.
Pasina ma enzymes, acetate neformate hazvigone kuoxidized patembiricha yemumba. FDH (formate dehydrogenase) neCoA (coenzyme A) zvinokonzeresa oxidation yeformate neacetate kuti zvigadzire carbon dioxide, zvichiteerana (Eqs. 16, 17) 57, 58, 59. Mabhakitiriya akasiyana-siyana anokwanisa kugadzira ma enzymes aya, uye mabhakitiriya eheterotrophic, anoti Bacillus subtilis (PTCC #1204 (Persian Type Culture Collection), inozivikanwawo seNCIMB #13061 (International Collection of Bacteria, Yeast, Phage, Plasmids, Plant Seeds and Plant Cell Tissue Cultures)) uye Bacillus amyloliquefaciens (PTCC #1732, NCIMB #12077), zvakashandiswa muchidzidzo ichi. Mabhakitiriya aya akakurira mune medium ine meat peptone (5 g/L) uye meat extract (3 g/L), inonzi nutrient broth (NBR) (105443 Merck).
Saka, maformula mana akagadzirwa kuti akonzere calcium carbonate precipitation achishandisa masource maviri ecalcium uye mabhakitiriya maviri: calcium formate neBacillus subtilis (FS), calcium formate neBacillus amyloliquefaciens (FA), calcium acetate neBacillus subtilis (AS), uye calcium acetate neBacillus amyloliquefaciens (AA).
Muchikamu chekutanga chekugadzira bvunzo, bvunzo dzakaitwa kuti dzione musanganiswa wakanakisa waizowana kugadzirwa kwakanyanya kwecalcium carbonate. Sezvo mienzaniso yevhu yaive necalcium carbonate, bvunzo dzekutanga dzakagadzirwa kuti dziyere nemazvo CaCO3 inogadzirwa nemisanganiswa yakasiyana, uye musanganiswa we culture medium ne calcium source solutions wakaongororwa. Pamusanganiswa wega wega we calcium source solution nebacteria solution yakatsanangurwa pamusoro (FS, FA, AS, uye AA), zvinhu zve optimization (calcium source concentration, curing time, bacteria solution concentration yakayerwa ne optical density yesolution (OD), calcium source to bacteria solution ratio, uye pH) zvakatorwa uye zvakashandiswa mu sand dune treatment wind tunnel tests dzakatsanangurwa muzvikamu zvinotevera.
Pamusanganiswa wega wega, kuyedza 150 kwakaitwa kuti kudzidze mhedzisiro yemvura inonaya yeCaCO3 uye kuongorora zvinhu zvakasiyana-siyana, zvinoti kuwanda kwecalcium source, nguva yekuporesa, kukosha kwebhakitiriya OD, chiyero checalcium source kune bacterial solution uye pH panguva yekuoxidation yezvinhu zvipenyu (Tafura 1). Huwandu hwepH hwemaitiro akagadziriswa hwakasarudzwa zvichibva pamakori ekukura eBacillus subtilis neBacillus amyloliquefaciens kuitira kuti kukura kukurumidze. Izvi zvinotsanangurwa zvakadzama muchikamu cheMhedzisiro.
Matanho anotevera akashandiswa kugadzirira sampuro dzechikamu chekugadzirisa. Mhinduro yeMICP yakatanga kugadzirwa nekugadzirisa pH yekutanga yenzvimbo yekumera uye yozoiswa otomatiki pa121 °C kwemaminitsi gumi nemashanu. Dambudziko racho rakazoiswa mumhepo ine laminar uye rakachengetwa mu shakeing incubator pa30 °C uye 180 rpm. Kana OD yemabhakitiriya yasvika padanho raidiwa, yakasanganiswa ne calcium source solution muchikamu chaidiwa (Mufananidzo 1a). Mhinduro yeMICP yakabvumirwa kuita uye kuoma mu shakeing incubator pa220 rpm uye 30 °C kwenguva yakasvika pachinangwa chaidiwa. CaCO3 yakakamurwa mushure meku centrifugation pa6000 g kwemaminitsi mashanu uye yozoomeswa pa40 °C kugadzirira sampuro dze calcimeter test (Mufananidzo 1b). Mvura inonaya yeCaCO3 yakazoyerwa uchishandisa Bernard calcimeter, uko CaCO3 powder inopindirana ne1.0 N HCl (ASTM-D4373-02) kuti ibudise CO2, uye huwandu hwegasi iri hunoyera huwandu hweCaCO3 (Mufananidzo 1c). Kuti ishandure huwandu hweCO2 kuita CaCO3 content, calibration curve yakagadzirwa nekusuka pure CaCO3 powder ne1 N HCl uye kuigadzira ichienzaniswa neCO2 yakashanduka. Maumbirwo uye kuchena kwepure CaCO3 powder zvakaongororwa uchishandisa SEM imaging uye XRD analysis. Optical microscope ine kukura kwe1000 yakashandiswa kudzidza kuumbwa kwecalcium carbonate yakakomberedza mabhakitiriya, chikamu checalcium carbonate yakagadzirwa, uye mashandiro emabhakitiriya.
Dejegh Basin inzvimbo inozivikanwa zvikuru ine ivhu rakakuvara zvakanyanya kumaodzanyemba kwakadziva kumadokero kweFars Province muIran, uye vaongorori vakaunganidza ivhu rakakuvara nemhepo kubva munzvimbo iyi. Ivhu rakatorwa kubva pamusoro pevhu kuti riitwe chidzidzo. Kuongororwa kwezviratidzo paivhu kwakaratidza kuti ivhu rakanga risina kurongwa zvakanaka nejecha rine silt uye rakaiswa muchikamu cheSP-SM zvichienderana neUnified Soil Classification System (USC) (Mufananidzo 2a). Ongororo yeXRD yakaratidza kuti ivhu reDejegh raive rakanyanya kuumbwa ne calcite ne quartz (Mufananidzo 2b). Pamusoro pezvo, ongororo yeEDX yakaratidza kuti zvimwe zvinhu zvakaita seAl, K, uye Fe zvaivepowo muzvikamu zvidiki.
Kugadzirira madutu emurabhoritari kuti aedzwe kukanganiswa nemhepo, ivhu rakapwanywa kubva pakukwirira kwe170 mm kuburikidza nefunnel yedhayamita ye10 mm kuenda panzvimbo yakasimba, zvichikonzera dune rakajairika re60 mm pakureba uye 210 mm pakureba. Muzvisikwa, madutu ejecha ane density yakaderera anoumbwa nemaitiro eaeolian. Saizvozvowo, sampuro yakagadzirwa uchishandisa maitiro ari pamusoro apa yaive nedensity yakaderera, γ = 14.14 kN/m³, ichigadzira jecha cone rakaiswa pamusoro penzvimbo yakatwasuka ine angle yekuzorora yeinenge 29.7°.
Mhinduro yakanakisisa yeMICP yakawanikwa muchikamu chakapfuura yakapfapfaidzwa padune slope pachiyero che1, 2 uye 3 lm-2 uye sampuro dzakazochengetwa mu incubator pa30 °C (Mufananidzo 3) kwemazuva mapfumbamwe (kureva nguva yakanakisisa yekupisa) uye dzozoendeswa kunoongororwa nemhepo.
Pakurapa kwega kwega, sampuli ina dzakagadzirwa, imwe yekuyera huwandu hwecalcium carbonate uye simba repamusoro uchishandisa penetrometer, uye sampuli nhatu dzakasara dzakashandiswa pakuyedza kukanganiswa kwevhu nemafambiro matatu akasiyana. Mukuyedza kwemhepo ine tunnel, huwandu hwekukanganiswa kwevhu hwakaonekwa nekumhanya kwakasiyana kwemhepo, uye ipapo kumhanya kwekupatsanurwa kwemuganho wemuenzaniso wega wega wekurapa kwakaongororwa uchishandisa puratifomu yehuwandu hwekukanganiswa kwevhu uchienzaniswa nekumhanya kwemhepo. Pamusoro pekuyedza kukanganiswa kwemhepo, sampuli dzakarapwa dzakaitwa jecha rinoputika (kureva, kuyedza kusvetuka). Dzimwe sampuli mbiri dzakagadzirwa nekuda kwechinangwa ichi pamatanho ekushandiswa e2 ne3 L m−2. Kuyedza kupiswa kwejecha kwakagara kwemaminitsi gumi nemashanu nekufamba kwe120 gm−1, iyo iri mukati mehuwandu hwakasarudzwa muzvidzidzo zvekare60,61,62. Daro rakatwasuka pakati pemuromo weabrasive nedune base raive 800 mm, riri 100 mm pamusoro petuneal pasi. Nzvimbo iyi yakagadzirirwa zvekuti dzinenge dzese zvidimbu zvejecha zvinosvetuka zvakawira padune.
Kuedzwa kwemhepo ine tunnel yemhepo kwakaitwa mu tunnel yemhepo yakavhurika ine urefu hwemamita masere, upamhi hwemamita 0.4 uye kureba kwemita imwe (Mufananidzo 4a). Tunnel yemhepo yakagadzirwa nesimbi dzakabatidzwa uye inogona kugadzira kumhanya kwemhepo kusvika 25 m/s. Pamusoro pezvo, frequency converter inoshandiswa kugadzirisa frequency yefeni uye kuwedzera zvishoma nezvishoma frequency kuti iwane kumhanya kwemhepo kwakanangana nayo. Mufananidzo 4b unoratidza dhayagiramu yejecha rakaparadzwa nemhepo uye chimiro chekukurumidza kwemhepo chakayerwa mu tunnel yemhepo.
Chekupedzisira, kuti tienzanise mhedzisiro yemushonga weMICP usina urealytic wakatsanangurwa muchidzidzo chino nemhedzisiro yebvunzo yekudzora yeMICP yeurealytic, sampuro dzemadune dzakagadzirwawo ndokurapwa nemushonga wezvipenyu une urea, calcium chloride uye Sporosarcina pasteurii (sezvo Sporosarcina pasteurii ine kugona kukuru kwekugadzira ureaase63). Kuwanda kwechiedza chemushonga webhakitiriya kwaive 1.5, uye huwandu hweurea necalcium chloride hwaive 1 M (hwakasarudzwa zvichibva pane zvaikurudzirwa muzvidzidzo zvekare36,64,65). Nzvimbo yekurera yaive nemuto wezvinovaka muviri (8 g/L) uye urea (20 g/L). Mushonga webhakitiriya wakapfapfaidzwa pamusoro pedune ndokusiyiwa kwemaawa makumi maviri nemana kuti ubatanidzwe nebhakitiriya. Mushure memaawa makumi maviri nemana ekunamira, mushonga wekusimbisa (calcium chloride uye urea) wakapfapfaidzwa. Mushonga wekudzora weUrealytic MICP unonzi UMC. Kuwanda kwecalcium carbonate muvhu rakagadziriswa urealytic nerisina urealytic kwakawanikwa nekugezwa zvichienderana nemaitiro akataurwa naChoi et al.66.
Mufananidzo 5 unoratidza kukura kweBacillus amyloliquefaciens neBacillus subtilis munzvimbo yekumera (mushonga unovaka muviri) ine pH yekutanga iri pakati pe5 kusvika 10. Sezvakaratidzwa mumufananidzo, Bacillus amyloliquefaciens neBacillus subtilis dzakakura nekukurumidza pa pH 6-8 ne7-9, zvichiteerana. Nokudaro, iyi pH range yakagamuchirwa muchikamu chekugadzirisa.
Makoridho ekukura e (a) Bacillus amyloliquefaciens uye (b) Bacillus subtilis pa pH dzakasiyana dzepakutanga dzenzvimbo inovaka muviri.
Mufananidzo 6 unoratidza huwandu hwekabhoni dhayokisaidhi inogadzirwa muBernard limemeter, iyo inomiririra precipitated calcium carbonate (CaCO3). Sezvo chimwe chinhu chakagadziriswa mumusanganiswa wega wega uye zvimwe zvinhu zvakasiyana-siyana, poindi yega yega pamagrafu aya inoenderana nehuwandu hwakanyanya hwekabhoni dhayokisaidhi mune iyo seti yekuyedza. Sezvakaratidzwa mumufananidzo, sezvo huwandu hwekabhoni source hwakawedzera, kugadzirwa kwecalcium carbonate kwakawedzera. Nokudaro, huwandu hwekabhoni source hunokanganisa zvakananga kugadzirwa kwecalcium carbonate. Sezvo calcium source nekabhoni source zvakafanana (kureva, calcium formate necalcium acetate), calcium ions yakawanda inoburitswa, calcium carbonate yakawanda inoumbwa (Mufananidzo 6a). Mumafomu eAS neAA, kugadzirwa kwecalcium carbonate kwakaramba kuchiwedzera nenguva yekurapwa kusvika huwandu hwekurapwa hwava kuda kuchinja mushure memazuva mapfumbamwe. Mumafomu eFA, mwero wekuumbwa kwecalcium carbonate wakaderera apo nguva yekurapwa yaipfuura mazuva matanhatu. Zvichienzaniswa nedzimwe nzira, fomura FS yakaratidza mwero wakaderera wekuumbwa kwecalcium carbonate mushure memazuva matatu (Mufananidzo 6b). Mumafomura eFA neFS, 70% ne87% yehuwandu hwekugadzirwa kwecalcium carbonate hwakawanikwa mushure memazuva matatu, nepo mumafomura eAA neAS, chikamu ichi chaingova 46% ne45% chete, zvichiteerana. Izvi zvinoratidza kuti fomura yeformic acid ine chiyero chepamusoro chekuumbwa kweCaCO3 pakutanga zvichienzaniswa nefomura yeacetate. Zvisinei, chiyero chekuumbwa chinoderera nekuwedzera kwenguva yekuporesa. Zvinogona kugumiswa kubva paMufananidzo 6c kuti kunyangwe pahuwandu hwebhakitiriya huri pamusoro peOD1, hapana mupiro wakakosha pakuumbwa kwecalcium carbonate.
Kuchinja kwehuwandu hweCO2 (uye huwandu hweCaCO3 hunoenderana) kwakayerwa neBernard calcimeter sebasa re (a) huwandu hwecalcium source, (b) nguva yekuisa, (c) OD, (d) pH yekutanga, (e) chiyero checalcium source kune bacterial solution (yega yega fomura); uye (f) huwandu hwakanyanya hwecalcium carbonate inogadzirwa pamusanganiswa wega wega wecalcium source nemabacteria.
Nezvemhedzisiro ye pH yekutanga ye medium, Mufananidzo 6d unoratidza kuti kune FA ne FS, kugadzirwa kweCaCO3 kwakasvika pahuwandu hwakanyanya pa pH 7. Izvi zvinoenderana nezvidzidzo zvekare zvekuti ma enzymes eFDH akanyanya kugadzikana pa pH 7-6.7. Zvisinei, kune AA ne AS, mvura yeCaCO3 yakawedzera apo pH yakadarika 7. Zvidzidzo zvekare zvakaratidzawo kuti pH range yakanakisa yebasa reCoA enzyme iri kubva pa8 kusvika 9.2-6.8. Tichifunga kuti pH ranges yakanakisa yebasa reCoA enzyme uye kukura kweB. amyloliquefaciens ndeye (8-9.2) uye (6-8), zvichiteerana (Mufananidzo 5a), pH yakanakisa yeAA formula inotarisirwa kuva 8, uye pH ranges mbiri dzinopindirana. Izvi zvakasimbiswa nekuyedza, sezvakaratidzwa muMufananidzo 6d. Sezvo pH yakanakisisa yekukura kweB. subtilis iri 7-9 (Mufananidzo 5b) uye pH yakanakisisa yebasa reCoA enzyme iri 8-9.2, goho repamusoro remvura yeCaCO3 rinotarisirwa kuva muhuwandu hwepH hwe8-9, izvo zvinosimbiswa neMufananidzo 6d (kureva, pH yakanaka yemvura ye9). Mhedzisiro inoratidzwa muMufananidzo 6e inoratidza kuti chiyero chakanaka che calcium source solution kune bacterial solution i1 ye acetate ne formate solutions. Kuti tienzanise, mashandiro emafomula akasiyana (kureva, AA, AS, FA, uye FS) akaongororwa zvichibva pakugadzirwa kwakanyanya kweCaCO3 pasi pemamiriro akasiyana (kureva, huwandu hwecalcium source, nguva yekuporesa, OD, chiyero checalcium source kune bacterial solution, uye pH yekutanga). Pakati pemafomula akadzidzwa, fomula FS yaive neCaCO3 production yakakwira, yaive inenge katatu kupfuura fomula AA (Mufananidzo 6f). Kuedza mana kwekudzivirira kusina mabhakitiriya kwakaitwa kune ese masource ecalcium uye hapana CaCO3 precipitation yakaonekwa mushure memazuva makumi matatu.
Mifananidzo ye optical microscopy yemafomu ese yakaratidza kuti vaterite ndiyo yaive chikamu chikuru chakaumbwa calcium carbonate (Mufananidzo 7). Makristaro evaterite aive akaita sedenderedzwa69,70,71. Zvakaonekwa kuti calcium carbonate yaiwira pamasero ebhakitiriya nekuti pamusoro pemasero ebhakitiriya paive negative charge uye yaigona kushanda semushonga we divalent cations. Tichitora formulation FS semuenzaniso muchidzidzo ichi, mushure memaawa makumi maviri nemana, calcium carbonate yakatanga kuumbwa pamamwe masero ebhakitiriya (Mufananidzo 7a), uye mushure memaawa makumi mana nemasere, huwandu hwemasero ebhakitiriya akaputirwa necalcium carbonate hwakawedzera zvakanyanya. Pamusoro pezvo, sezvakaratidzwa muMufananidzo 7b, zvidimbu zvevaterite zvaigonawo kuonekwa. Pakupedzisira, mushure memaawa makumi manomwe nemaviri, huwandu hwakawanda hwebhakitiriya hwairatidzika kunge hwakasungwa nekristaro dzevaterite, uye huwandu hwezvidimbu zvevaterite hwakawedzera zvakanyanya (Mufananidzo 7c).
Kuongororwa kweCaCO3 precipitation muFS compositions nekufamba kwenguva: (a) 24, (b) 48 uye (c) 72 h.
Kuti vaongorore zvakawanda nezvechimiro chechikamu chakagadziriswa, X-ray diffraction (XRD) uye SEM analysis yeupfu dzakaitwa. XRD spectra (Mufananidzo 8a) uye SEM micrographs (Mufananidzo 8b, c) dzakasimbisa kuvapo kwemakristaro evaterite, sezvo aive nechimiro chakafanana nelettuce uye kubatana pakati pemakristaro evaterite nemakristaro eprecipitate kwakaonekwa.
(a) Kuenzaniswa kwemaX-ray diffraction spectra eCaCO3 yakagadzirwa uye vaterite. SEM micrographs yevaterite pa (b) 1 kHz uye (c) 5.27 kHz kukura, zvichiteerana.
Mhedzisiro yemiedzo yemhepo inoratidzwa muMufananidzo 9a, b. Zvinogona kuonekwa kubva paMufananidzo 9a kuti kumhanya kwemhepo (TDV) kwejecha risina kugadziriswa kunosvika 4.32 m/s. Pakuiswa kwe1 l/m² (Mufananidzo 9a), mitsetse yemitsetse yekurasikirwa kwevhu yezvikamu FA, FS, AA neUMC yakafanana neyedune risina kugadziriswa. Izvi zvinoratidza kuti kurapwa pakushandiswa uku hakushande uye kana kumhanya kwemhepo kwapfuura TDV, goko revhu rakatetepa rinonyangarika uye mwero wekubviswa kwevhu wedune wakafanana newedune risina kugadziriswa. Kudonha kwevhu kwechikamu AS kwakadererawo pane kwezvimwe zvikamu zvine abscissas yakaderera (kureva TDV) (Mufananidzo 9a). Miseve iri muMufananidzo 9b inoratidza kuti pakumhanya kwemhepo kwakanyanya kwe25 m/s, hapana kudonha kwakaitika mumadune akagadziriswa pakushandiswa kwe2 ne3 l/m². Nemamwe mashoko, kune FS, FA, AS neUMC, madunes ainyanya kutsungirira kukanganiswa nemhepo kwakakonzerwa nekuiswa kweCaCO³ pahuwandu hwekushandiswa kwe2 ne3 l/m² pane kumhanya kwemhepo kwakanyanya (kureva 25 m/s). Saka, kukosha kweTDV kwe25 m/s kwakawanikwa mumiedzo iyi ndiyo muganho wakaderera wehuwandu hwekushandiswa hunoratidzwa muMufananidzo 9b, kunze kwenyaya yeAA, uko TDV inenge yakaenzana nekumhanya kwakanyanya kwemhepo.
Kuedzwa kwekukanganiswa kwemhepo (a) Kudzikira kwehuremu zvichienzaniswa nekumhanya kwemhepo (chiyero chekushandisa 1 l/m2), (b) Kumhanya kwekubvisa threshold zvichienzaniswa nekumhanya kwekushandisa uye fomura (CA yecalcium acetate, CF yecalcium formate).
Mufananidzo 10 unoratidza kuputsika kwevhu pamusoro pejecha rakagadziriswa nenzira dzakasiyana uye mwero wekushandiswa mushure mekuyedzwa kwejecha uye mhedzisiro yehuwandu inoratidzwa muMufananidzo 11. Nyaya isina kurapwa haina kuratidzwa nekuti haina kuratidza kuramba uye yakaputsika zvachose (kurasikirwa kwehuwandu hwese) panguva yekuyedzwa kwejecha. Zviri pachena kubva kuMufananidzo 11 kuti sampuro yakarapwa nebiocomposition AA yakarasikirwa ne83.5% yehuremu hwayo pachiyero chekushandiswa che2 l/m2 nepo mimwe sampuro yese yakaratidza pasi pe30% yekuputsika panguva yekuyedzwa kwejecha. Pakawedzerwa mwero wekushandiswa kusvika pa3 l/m2, sampuro dzese dzakarapwa dzakarasikirwa pasi pe25% yehuremu hwadzo. Pamwero wese wekushandiswa, compound FS yakaratidza kuramba kwakanyanya kuputsika kwejecha. Kudzivirira kwakanyanya uye kushoma kwekuputika mumasampuli akarapwa eFS neAA kunogona kuverengerwa nekuda kwemvura yakanyanya uye shoma yeCaCO3 (Mufananidzo 6f).
Mhedzisiro yekuputirwa kwejecha rine zvidimbu zvakasiyana pakuyerera kwe2 ne3 l/m2 (miseve inoratidza divi remhepo, michinjikwa inoratidza divi remhepo yakatarisana nendege yemufananidzo).
Sezvakaratidzwa muMufananidzo 12, huwandu hwecalcium carbonate mumafomula ese hwakawedzera sezvo huwandu hwekushandiswa hwakawedzera kubva pa1 L/m² kusvika pa3 L/m². Pamusoro pezvo, pahuwandu hwese hwekushandiswa, fomula ine huwandu hwepamusoro hwecalcium carbonate yaive FS, ichiteverwa neFA neUMC. Izvi zvinoratidza kuti mafomula aya anogona kunge aine resistance yakakura pamusoro.
Mufananidzo 13a unoratidza shanduko mukuramba kwemvura pamusoro pevhu risina kurapwa, kudzorwa uye kurapwa kwakayerwa nekuyedzwa kwepermeameter. Kubva pamufananidzo uyu, zviri pachena kuti kuramba kwemvura pamusoro pevhu reUMC, AS, FA neFS kwakawedzera zvakanyanya nekuwedzera kwehuwandu hwekushandisa. Zvisinei, kuwedzera kwesimba remvura pamusoro kwaive kudiki muAA formulation. Sezvakaratidzwa pamufananidzo, FA neFS formulations dzeMICP isina urea-degraded MICP dzine mukana wepamusoro uri nani zvichienzaniswa neMICP yakaora. Mufananidzo 13b unoratidza shanduko muTDV nekuramba kwemvura pamusoro pevhu. Kubva pamufananidzo uyu, zviri pachena kuti kune madunes ane kuramba kwemvura pamusoro kupfuura 100 kPa, kumhanya kwekubvisa mvura kuchapfuura 25 m/s. Sezvo kuramba kwemvura pamusoro pevhu kuchigona kuyerwa nyore nyore nepermeameter, ruzivo urwu runogona kubatsira kufungidzira TDV pasina kuyedzwa kwemhepo, nokudaro zvichishanda sechiratidzo chekudzora mhando yekushandiswa mumunda.
Mhedzisiro yeSEM ​​inoratidzwa muMufananidzo 14. Mifananidzo 14a-b inoratidza zvidimbu zvakakura zvesample yevhu isina kugadziriswa, izvo zvinoratidza pachena kuti yakabatana uye haina kubatana kwechisikigo kana simende. Mufananidzo 14c unoratidza SEM micrograph yesample yekudzora yakarapwa neMICP yakaora. Mufananidzo uyu unoratidza kuvapo kweCaCO3 precipitates se calcite polymorphs. Sezvakaratidzwa muMifananidzo 14d-o, CaCO3 yakagadziriswa inosunga zvidimbu pamwe chete; makristaro e spherical vaterite anogonawo kuonekwa muSEM micrographs. Mhedzisiro yechidzidzo ichi nezvidzidzo zvekare zvinoratidza kuti CaCO3 bonds dzakaumbwa se vaterite polymorphs dzinogonawo kupa simba rakanaka remakanika; mhedzisiro yedu inoratidza kuti resistance yepamusoro inowedzera kusvika 350 kPa uye kumhanya kwekuparadzanisa kwemuganho kunowedzera kubva pa4.32 kusvika kupfuura 25 m/s. Mhedzisiro iyi inoenderana nemigumisiro yezvidzidzo zvekare zvekuti matrix yeMICP-precipitated CaCO3 ivaterite, ine simba remakanika uye inodzivirira kukurwa kwemhepo13,40 uye inogona kuchengetedza kukurwa kwemhepo kwakanaka kunyangwe mushure memazuva 180 ekushandiswa mumamiriro ekunze emunda13.
(a, b) SEM micrographs yevhu risina kugadziriswa, (c) MICP urea degradation control, (df) AA-treated samples, (gi) AS-treated samples, (jl) FA-treated samples, uye (mo) FS-treated samples pakushandiswa kwe3 L/m2 pakukura kwakasiyana.
Mufananidzo 14d-f unoratidza kuti mushure mekurapwa neAA compounds, calcium carbonate yakawira pamusoro uye pakati pejecha, nepo mamwe majecha asina kuputirwa akaonekwawo. Kune zvikamu zveAS, kunyangwe huwandu hweCaCO3 hwakaumbwa husina kuwedzera zvakanyanya (Mufananidzo 6f), huwandu hwekubatana pakati pejecha hunokonzerwa neCaCO3 hwakawedzera zvakanyanya zvichienzaniswa neAA compounds (Mufananidzo 14g-i).
Kubva paMifananidzo 14j-l ne14m-o zviri pachena kuti kushandiswa kwecalcium formate senzvimbo yecalcium kunotungamira kuwedzera kwemvura inonaya muCaCO3 zvichienzaniswa neAS compound, izvo zvinoenderana nekuyera kwecalcium meter muMufananidzo 6f. Iyi CaCO3 yekuwedzera inoita kunge yakanyanya kuiswa pajecha uye hazvireve kuti inovandudza kunaka kwekubatana. Izvi zvinosimbisa maitiro akamboonekwa: pasinei nekusiyana kwehuwandu hwemvura inonaya muCaCO3 (Mufananidzo 6f), maformula matatu (AS, FA neFS) haana kusiyana zvakanyanya maererano nekushanda kweanti-eolian (mhepo) (Mufananidzo 11) uye kuramba kwenzvimbo (Mufananidzo 13a).
Kuti tinyatsoona masero ebhakitiriya akafukidzwa neCaCO3 uye chiratidzo chebhakitiriya pamakristaro akadonha, maSEM micrographs akatorwa uye mhedzisiro yacho inoratidzwa muMufananidzo 15. Sezvakaratidzwa, calcium carbonate inodonha pamasero ebhakitiriya uye inopa nuclei inodiwa kuti mvura idonhe ipapo. Mufananidzo wacho unoratidzawo kubatana kunoshanda uye kusina kushanda kunokonzerwa neCaCO3. Zvinogona kugumiswa kuti chero kuwedzera kwekubatana kusina kushanda hakurevi kuti pane kuvandudzwa kwakawanda mumaitiro emakanika. Naizvozvo, kuwedzera mvura yeCaCO3 hakurevi kuti kune simba rakawanda remakanika uye maitiro emvura anoita basa rakakosha. Pfungwa iyi yakadzidzwawo mumabasa aTerzis naLaloui72 naSoghi naAl-Kabani45,73. Kuti tiongorore hukama huripo pakati pemaitiro emvura nesimba remakanika, zvidzidzo zveMICP zvinoshandisa µCT imaging zvinokurudzirwa, izvo zviri kunze kwezvidzidzo izvi (kureva, kuunza musanganiswa wakasiyana wecalcium source nemabhakitiriya eMICP isina ammonia).
CaCO3 yakakonzera mabhondi anoshanda uye asina kushanda mumasampuli akarapwa ne (a) AS composition uye (b) FS composition uye yakasiya chiratidzo chemasero ebhakitiriya padhaka.
Sezvakaratidzwa muMifananidzo 14j-o na15b, kune firimu reCaCO (zvichienderana neongororo yeEDX, huwandu hwechikamu chechinhu chimwe nechimwe mufirimu icarbon 11%, oxygen 46.62% uye calcium 42.39%, iyo iri pedyo zvikuru nechikamu cheCaCO muMufananidzo 16). Firimu iri rinofukidza makristaro evaterite nezvidimbu zvevhu, zvichibatsira kuchengetedza hunhu hwesystem yevhu-sediment. Kuvapo kwefirimu iri kwakaonekwa chete mumienzaniso yakarapwa neformate-based formulation.
Tafura 2 inoenzanisa simba repamusoro, kumhanya kwekubviswa kwevhu, uye huwandu hweCaCO3 hunokonzerwa nebioinduced muvhu rakarapwa nenzira dzeMICP dzinoora urea uye dzisina kuora urea muzvidzidzo zvekare uye muchidzidzo chino. Zvidzidzo pamusoro pekudzivirira kukanganiswa kwevhu nemhepo kwesampuli dzemadune dzakarapwa neMICP zvakaganhurirwa. Meng nevamwe vake vakaongorora kudzivirira kukanganiswa kwevhu nemhepo kwesampuli dzemadune dzakarapwa neMICP vachishandisa muchina wekubvisa mashizha,13 nepo muchidzidzo chino, sampuli dzemadune dzisina kuora urea (pamwe chete nedzinodzora kukanganiswa kwevhu neurea) dzakaedzwa mugomba remhepo uye dzakarapwa nemisanganiswa mina yakasiyana yemabhakitiriya nezvinhu.
Sezvatinoona, dzimwe ongororo dzakamboitwa dzakafunga nezvehuwandu hwepamusoro hwekushandiswa hunopfuura 4 L/m213,41,74. Zvakakosha kuziva kuti huwandu hwepamusoro hwekushandiswa hunogona kusashanda zviri nyore mumunda uyu nekuda kwemari inobatanidzwa nekupihwa kwemvura, kutakurwa uye kushandiswa kwehuwandu hwakawanda hwemvura. Huwandu hwakaderera hwekushandiswa hwakaita se1.62-2 L/m2 hwakawanawo simba rakanaka repamusoro rinosvika 190 kPa uye TDV inodarika 25 m/s. Muchidzidzo chino, madunes akarapwa neformate-based MICP isina urea degradation akawana simba guru repamusoro rakafanana nerakawanikwa nenzira yekuora kweurea muhuwandu hwakafanana hwekushandiswa (kureva, sampuli dzakarapwa neformate-based MICP isina urea degradation dzakakwanisawo kuwana huwandu hwakafanana hwesimba repamusoro sezvakataurwa naMeng et al., 13, Mufananidzo 13a) pahuwandu hwakakwira hwekushandiswa. Zvinogonawo kuonekwa kuti pakushandiswa kwe2 L/m2, goho recalcium carbonate rekuderedza kukanganiswa kwemhepo nekumhanya kwemhepo kwe25 m/s raive 2.25% yeformate-based MICP isina kukanganiswa kweurea, iyo iri pedyo zvikuru nehuwandu hunodiwa hweCaCO3 (kureva 2.41%) zvichienzaniswa nedunes dzakabatwa necontrol MICP nekukanganiswa kweurea nekumhanya kwemhepo kwakafanana (25 m/s).
Saka, zvinogona kugumiswa kubva patafura iyi kuti nzira yekuora kweurea uye nzira yekuora kweurea isina urea zvinogona kupa mashandiro anogamuchirwa maererano nekusagadzikana kwepamusoro uye TDV. Musiyano mukuru ndewekuti nzira yekuora kweurea isina urea haina ammonia uye nekudaro ine mhedzisiro yakaderera kune nharaunda. Pamusoro pezvo, nzira yeMICP yakavakirwa paformate isina kuora kweurea yakatsanangurwa muchidzidzo ichi inoita seinoshanda zviri nani pane nzira yeMICP yakavakirwa paacetate isina kuora kweurea. Kunyangwe Mohebbi nevamwe vake nzira yeMICP yakavakirwa paacetate isina kuora kweurea, chidzidzo chavo chakabatanidza mienzaniso panzvimbo dzakatsetseka9. Nekuda kwehuwandu hwakanyanya hwekuora kweurea hunokonzerwa nekuumbwa kwe eddy kwakatenderedza masampu edune uye shear inobuda, izvo zvinoguma neTDV yakaderera, kuora kwemhepo kwemasampu edune kunotarisirwa kuve pachena kupfuura kwenzvimbo dzakatsetseka nekumhanya kumwe chete.