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Izivuthuvuthu zothuli ziyingozi enkulu kumazwe amaninzi kwihlabathi liphela ngenxa yempembelelo yazo eyonakalisayo kwezolimo, impilo yabantu, uthungelwano lwezothutho kunye neziseko zophuhliso. Ngenxa yoko, ukukhukuliseka komoya kuthathwa njengengxaki yehlabathi. Enye yeendlela ezinobuhlobo nokusingqongileyo zokunciphisa ukukhukuliseka komoya kukusetyenziswa kwe-microbial induced carbonate precipitation (MICP). Nangona kunjalo, iimveliso ze-MICP esekwe kwi-urea-degradation, ezifana ne-ammonia, azilungelanga xa ziveliswa ngobuninzi. Olu phononongo lubonisa iindlela ezimbini ze-calcium formate bacteria zokonakalisa i-MICP ngaphandle kokuvelisa i-urea kwaye luthelekisa ngokupheleleyo ukusebenza kwazo neendlela ezimbini ze-non-ammonia-producing calcium acetate bacteria. Iintsholongwane eziqwalaselweyo yiBacillus subtilis kunye neBacillus amyloliquefaciens. Okokuqala, amaxabiso aphuculweyo ezinto ezilawula ukwakheka kweCaCO3 amiselwa. Uvavanyo lwe-wind tunnel lwenziwa kwiisampulu zesanti eziphathwe ngeendlela eziphuculweyo, kwaye ukumelana nokukhukuliseka komoya, isantya somda wokukrazula, kunye nokumelana nokuqhushumba kwesanti kwalinganiswa. Ii-allomorphs zeCalcium carbonate (CaCO3) zivavanywe kusetyenziswa i-optical microscopy, i-scanning electron microscopy (SEM), kunye nohlalutyo lwe-X-ray diffraction. Iifomyula ezisekelwe kwi-calcium formate zisebenze ngcono kakhulu kuneefomyula ezisekelwe kwi-acetate ngokwemigaqo yokwakheka kwe-calcium carbonate. Ukongeza, i-B. subtilis ivelise i-calcium carbonate engaphezulu kune-B. amyloliquefaciens. Ii-SEM micrographs zibonise ngokucacileyo ukubopha kunye nokuprintwa kweebhaktheriya ezisebenzayo nezingasebenziyo kwi-calcium carbonate ezibangelwa kukusa. Zonke iifomyula zinciphise kakhulu ukukhukuliseka komoya.
Ukukhukuliseka komoya kudala kwaziwa njengengxaki enkulu ejongene nemimandla eyomileyo neyomileyo efana nomzantsi-ntshona we-United States, intshona yeTshayina, iSahara Afrika, kunye nenxalenye enkulu ye-Middle East1. Imvula encinci kwiindawo ezomileyo nezinomileyo kakhulu iguqule iindawo ezinkulu zale mimandla yaba ziintlango, iindunduma zesanti, kunye nomhlaba ongalinywanga. Ukukhukuliseka komoya okuqhubekayo kubeka umngcipheko kwindalo esingqongileyo kwiziseko zophuhliso ezifana nothungelwano lwezothutho, umhlaba wezolimo, kunye nomhlaba wemizi-mveliso, okukhokelela kwiimeko ezimbi zokuhlala kunye neendleko eziphezulu zophuhliso lwedolophu kwezi ngingqi2,3,4. Okubalulekileyo kukuba, ukukhukuliseka komoya akuchaphazeli nje kuphela indawo apho kwenzeka khona, kodwa kukwabangela iingxaki zempilo kunye noqoqosho kwiindawo ezikude njengoko kuthutha amasuntswana ngomoya ukuya kwiindawo ezikude nomthombo5,6.
Ulawulo lokukhukuliseka komoya luseyingxaki yehlabathi. Iindlela ezahlukeneyo zokuzinzisa umhlaba zisetyenziswa ukulawula ukukhukuliseka komoya. Ezi ndlela ziquka izinto ezifana nokusetyenziswa kwamanzi7, ii-oil mulch8, ii-biopolymers5, i-microbial induced carbonate precipitation (MICP)9,10,11,12 kunye ne-enzyme induced carbonate precipitation (EICP)1. Ukumanzisa umhlaba yindlela eqhelekileyo yokunciphisa uthuli endle. Nangona kunjalo, ukufuma kwayo ngokukhawuleza kwenza le ndlela isebenze kancinci kwiindawo ezomileyo nezingenamanzi1. Ukusetyenziswa kwee-oil mulching compounds kwandisa ukuhlangana kwesanti kunye nokungqubana phakathi kwamaqhekeza. Ipropati yazo edibeneyo ibopha iinkozo zesanti kunye; nangona kunjalo, ii-oil mulch nazo zibangela ezinye iingxaki; umbala wazo omnyama unyusa ukufunxwa kobushushu kwaye ukhokelela ekufeni kwezityalo kunye neentsholongwane. Ivumba lazo kunye nomsi zinokubangela iingxaki zokuphefumla, kwaye okona kubaluleke kakhulu, ixabiso lazo eliphezulu lolunye umqobo. Ii-Biopolymers zezinye zeendlela ezisandula ukucetyiswa ezinobuhlobo nokusingqongileyo zokunciphisa ukukhukuliseka komoya; zikhutshwa kwimithombo yendalo efana nezityalo, izilwanyana kunye neebhaktheriya. I-Xanthan gum, i-guar gum, i-chitosan kunye ne-gellan gum zezona biopolymers zisetyenziswa kakhulu kwizicelo zobunjineli5. Nangona kunjalo, ii-biopolymers ezinyibilikayo emanzini zinokulahlekelwa ngamandla kwaye ziphume emhlabeni xa zichatshazelwe ngamanzi13,14. I-EICP ibonakalisiwe njengendlela esebenzayo yokunciphisa uthuli kwiindlela ezahlukeneyo kubandakanya iindlela ezingagayiweyo, amachibi angasemva kunye neendawo zokwakha. Nangona iziphumo zayo zikhuthaza, ezinye iingxaki ezinokubakho kufuneka ziqwalaselwe, njengeendleko kunye nokungabikho kweendawo ze-nucleation (ezikhawulezisa ukwakheka kunye nokuna kweekristale zeCaCO315,16).
I-MICP yaqala ukuchazwa ngasekupheleni kwenkulungwane ye-19 nguMurray no-Irwin (1890) kunye noSteinmann (1901) kuphando lwabo lokuwohloka kwe-urea ziintsholongwane zaselwandle17. I-MICP yinkqubo yendalo yebhayoloji equka imisebenzi eyahlukeneyo yeentsholongwane kunye neenkqubo zeekhemikhali apho i-calcium carbonate ibangelwa kukusabela kwee-ion ze-carbonate ezivela kwi-metabolites zentsholongwane kunye nee-ion ze-calcium kwindawo esingqongileyo18,19. I-MICP equka umjikelo we-nitrogen obola i-urea (i-MICP ebola i-urea) lolona hlobo luqhelekileyo lwe-microbial-induced carbonate precipitation, apho i-urease eveliswa ziintsholongwane ivuselela i-hydrolysis ye-urea20,21,22,23,24,25,26,27 ngolu hlobo lulandelayo:
Kwi-MICP ebandakanya umjikelo wekhabhoni we-organic salt oxidation (i-MICP engenalo uhlobo lokubola kwe-urea), iibhaktheriya ze-heterotrophic zisebenzisa iityuwa ze-organic ezifana ne-acetate, i-lactate, i-citrate, i-succinate, i-oxalate, i-malate kunye ne-glyoxylate njengemithombo yamandla ukuvelisa iiminerali ze-carbonate28. Ukuba kukho i-calcium lactate njengomthombo wekhabhoni kunye nee-calcium ions, impendulo yekhemikhali yokwakheka kwe-calcium carbonate iboniswe kwi-equation (5).
Kwinkqubo ye-MICP, iiseli zebhaktiriya zibonelela ngeendawo ze-nucleation ezibaluleke kakhulu ekungeneni kwe-calcium carbonate; umphezulu weseli yebhaktiriya une-negative charge kwaye unokusebenza njenge-adsorbent ye-divalent cations ezifana ne-calcium ions. Ngokufaka i-calcium ions kwiiseli zebhaktiriya, xa uxinano lwe-carbonate ion lwanele, i-calcium cations kunye ne-carbonate anions ziyasabela kwaye i-calcium carbonate ingena kumphezulu webhaktiriya29,30. Inkqubo ingashwankathelwa ngolu hlobo lulandelayo31,32:
Iikristale zecalcium carbonate eziveliswa yi-biogenerated zinokwahlulwa zibe ziintlobo ezintathu: i-calcite, i-vaterite, kunye ne-aragonite. Phakathi kwazo, i-calcite kunye ne-vaterite zezona allomorphs zecalcium carbonate ezibangelwa ziibhaktheriya33,34. I-Calcite yeyona allomorphe yecalcium carbonate ezizinzileyo kakhulu kwi-thermodynamically. Nangona i-vaterite ibikwe ukuba iyakwazi ukuguquguquka, ekugqibeleni iguquka ibe yi-calcite36,37. I-Vaterite yeyona ixineneyo kwezi kristale. Yikristale ene-hexagonal enokukwazi ukuzalisa iimbobo ngcono kunezinye iikristale zecalcium carbonate ngenxa yobukhulu bayo obukhulu38. Zombini i-MICP eyonakaliswe yi-urea kunye ne-urea-undegraded zinokukhokelela ekuweni kwe-vaterite13,39,40,41.
Nangona i-MICP ibonakalise amandla athembisayo ekuzinziseni umhlaba onengxaki kunye nomhlaba osengozini yokukhukuliseka ngumoya42,43,44,45,46,47,48, enye yeemveliso ze-urea hydrolysis yi-ammonia, enokubangela iingxaki zempilo ezincinci ukuya kwezinzima kuxhomekeke kwinqanaba lokuchatshazelwa49. Esi siphumo esingesihle senza ukusetyenziswa kobu buchwepheshe bube yimpikiswano, ngakumbi xa iindawo ezinkulu zifuna ukunyangwa, njengokunciphisa uthuli. Ukongeza, ivumba le-ammonia alinyamezeleki xa inkqubo isenziwa ngamazinga aphezulu okusetyenziswa kunye nomthamo omkhulu, okunokuchaphazela ukusebenza kwayo okusebenzayo. Nangona uphando lwakutshanje lubonise ukuba ii-ion ze-ammonium zinokuncitshiswa ngokuziguqula zibe zezinye iimveliso ezifana ne-struvite, ezi ndlela azizisusi ngokupheleleyo ii-ion ze-ammonium50. Ke ngoko, kusekho imfuneko yokuphonononga ezinye izisombululo ezingavelisi ii-ion ze-ammonium. Ukusetyenziswa kweendlela zokubola kwe-non-urea kwi-MICP kunokubonelela ngesisombululo esinokubakho esingakhange sihlolwe kakuhle kumxholo wokunciphisa ukukhukuliseka komoya. UFattahi et al. baphande ngokuchithwa kwe-MICP engena-urea besebenzisa i-calcium acetate kunye ne-Bacillus megaterium41, ngelixa uMohebbi et al. basebenzisa i-calcium acetate kunye ne-Bacillus amyloliquefaciens9. Nangona kunjalo, uphando lwabo aluzange luthelekiswe neminye imithombo ye-calcium kunye neebhaktheriya ze-heterotrophic ezinokuthi ekugqibeleni ziphucule ukumelana nokukhukuliseka komoya. Kukwakho nokunqongophala koncwadi oluthelekisa iindlela zokukhukuliseka ezingena-urea kunye neendlela zokukhukuliseka kwe-urea ekunciphiseni ukukhukuliseka komoya.
Ukongeza, uninzi lwezifundo zokulawula ukukhukuliseka komoya kunye nolawulo lothuli zenziwe kwiisampuli zomhlaba ezinemiphezulu ethe tyaba.1,51,52,53 Nangona kunjalo, imiphezulu ethe tyaba ayixhaphakanga kakhulu kwindalo kuneenduli kunye neengxondorha. Yingakho iinduli zesanti ziyona ndawo ixhaphakileyo kwimimandla yasentlango.
Ukuze koyiswe ezi ntsilelo zikhankanyiweyo apha ngasentla, olu phononongo lujolise ekungeniseni iseti entsha yee-arhente zebhaktiriya ezingezizo i-ammonia. Ngenxa yesi sizathu, siqwalasele iindlela ze-MICP ezingezizo ezonakalisayo ze-urea. Ukusebenza kakuhle kwemithombo emibini ye-calcium (i-calcium formate kunye ne-calcium acetate) kuphandwe. Ngokolwazi lwababhali, ukuhla kwe-carbonate kusetyenziswa imithombo emibini ye-calcium kunye neendibaniselwano zebhaktiriya (oko kukuthi i-calcium formate-Bacillus subtilis kunye ne-calcium formate-Bacillus amyloliquefaciens) akukaphandwa kwizifundo zangaphambili. Ukukhethwa kwezi bhaktiriya kwakusekelwe kwii-enzymes ezizivelisayo ezikhuthaza ukubola kwe-calcium formate kunye ne-calcium acetate ukuze kwenziwe ukuhla kwe-microbial carbonate precipitation. Siyile uphando olucokisekileyo lovavanyo ukuze sifumane izinto ezifanelekileyo ezifana ne-pH, iintlobo zebhaktiriya kunye nemithombo ye-calcium kunye noxinzelelo lwazo, umlinganiselo webhaktiriya kwisisombululo somthombo we-calcium kunye nexesha lokuphiliswa. Okokugqibela, ukusebenza kakuhle kwale seti yee-bacterial agents ekuthinteleni ukukhukuliseka komoya ngokusebenzisa i-calcium carbonate precipitation kuphandwe ngokwenza uthotho lweemvavanyo zomoya kwimigxobhozo yesanti ukuze kuchongwe ubungakanani bokukhukuliseka komoya, isantya sokuqhekeka komgca kunye nokumelana nokuqhushumba komoya kwisanti, kunye nokulinganiswa kwe-penetrometer kunye nezifundo ze-microstructural (umz. uhlalutyo lwe-X-ray diffraction (XRD) kunye ne-scanning electron microscopy (SEM)) nazo zenziwe.
Ukuveliswa kwekhalsiyam carbonate kufuna ii-ion zekhalsiyam kunye nee-ion zekhalsiyam. Ii-ion zekhalsiyam zinokufunyanwa kwimithombo eyahlukeneyo yekhalsiyam efana nekhalsiyam chloride, ikhalsiyam hydroxide, kunye ne-skim milk powder54,55. Ii-ion zekhalsiyam zinokuveliswa ngeendlela ezahlukeneyo ze-microbial ezifana ne-urea hydrolysis kunye ne-aerobic okanye i-anaerobic oxidation ye-organic matter56. Kolu phononongo, ii-ion zekhalsiyam zifunyenwe kwi-oxidation reaction ye-formate kunye ne-acetate. Ukongeza, sisebenzise iityuwa zekhalsiyam ze-formate kunye ne-acetate ukuvelisa i-calcium carbonate ecocekileyo, ngoko ke yi-CO2 kunye ne-H2O kuphela ezifunyenwe njengeemveliso eziphuma kuyo. Kule nkqubo, yinto enye kuphela esebenza njengomthombo wekhalsiyam kunye nomthombo wekhalsiyam, kwaye akukho ammonia iveliswayo. Ezi mpawu zenza indlela yokuvelisa umthombo wekhalsiyam kunye nekhalsiyam esiyithathe njengethembisayo kakhulu.
Iimpendulo ezifanayo ze-calcium formate kunye ne-calcium acetate ukwenza i-calcium carbonate ziboniswe kwiifomyula (7)-(14). Iifomyula (7)-(11) zibonisa ukuba i-calcium formate iyanyibilika emanzini ukwenza i-formic acid okanye i-formate. Isisombululo ke ngoko singumthombo wee-ion ze-calcium kunye ne-hydroxide zasimahla (iifomyula 8 kunye ne-9). Ngenxa ye-oxidation ye-formic acid, ii-athomu ze-carbon kwi-formic acid ziguqulwa zibe yi-carbon dioxide (ifomyula 10). Ekugqibeleni kwenziwa i-calcium carbonate (iifomyula 11 kunye ne-12).
Ngokufanayo, i-calcium carbonate yenziwa nge-calcium acetate (ii-equations 13–15), ngaphandle kokuba i-acetic acid okanye i-acetate yenziwa endaweni ye-formic acid.
Ngaphandle kokubakho kwee-enzymes, i-acetate kunye ne-formate azinakwenziwa i-oxidized kubushushu begumbi. I-FDH (formate dehydrogenase) kunye ne-CoA (coenzyme A) zivuselela i-oxidation ye-formate kunye ne-acetate ukuze zenze i-carbon dioxide, ngokulandelelana (Eqs. 16, 17) 57, 58, 59. Iibhaktheriya ezahlukeneyo ziyakwazi ukuvelisa ezi enzymes, kwaye iibhaktheriya ze-heterotrophic, ezizezi: iBacillus subtilis (PTCC #1204 (Persian Type Culture Collection), eyaziwa ngokuba yi-NCIMB #13061 (International Collection of Bacteria, Yeast, Phage, Plasmids, Plant Seeds and Plant Cell Tissue Cultures)) kunye neBacillus amyloliquefaciens (PTCC #1732, NCIMB #12077), zisetyenzisiwe kolu phononongo. Ezi bhaktheriya zatyalwa kwindawo equlethe i-meat peptone (5 g/L) kunye ne-meat extract (3 g/L), ebizwa ngokuba yi-nutrient broth (NBR) (105443 Merck).
Ngoko ke, kwalungiselelwa iindlela ezine zokukhuthaza ukuhla kwe-calcium carbonate kusetyenziswa imithombo emibini ye-calcium kunye neebhaktheriya ezimbini: i-calcium formate kunye ne-Bacillus subtilis (FS), i-calcium formate kunye ne-Bacillus amyloliquefaciens (FA), i-calcium acetate kunye ne-Bacillus subtilis (AS), kunye ne-calcium acetate kunye ne-Bacillus amyloliquefaciens (AA).
Kwinxalenye yokuqala yoyilo lovavanyo, kwenziwe uvavanyo ukuze kuchongwe indibaniselwano efanelekileyo eya kufezekisa imveliso ephezulu ye-calcium carbonate. Ekubeni iisampulu zomhlaba zazine-calcium carbonate, iseti yovavanyo lokuqala lwenzelwe ukulinganisa ngokuchanekileyo i-CaCO3 eveliswe yimidibaniso eyahlukeneyo, kwaye kwavavanywa imixube yesisombululo se-culture medium kunye ne-calcium source. Kumdibaniso ngamnye wesisombululo somthombo we-calcium kunye ne-bacteria esichazwe apha ngasentla (FS, FA, AS, kunye ne-AA), izinto zokwenza ngcono (uxinzelelo lomthombo we-calcium, ixesha lokuphilisa, uxinano lwesisombululo se-bacteria olulinganiswa ngoxinano lwe-optical lwesisombululo (OD), umlinganiselo wesisombululo somthombo we-calcium ukuya kwi-bacteria, kunye ne-pH) zafunyanwa kwaye zasetyenziswa kuvavanyo lwe-wind tunnel yonyango lwesanti oluchazwe kumacandelo alandelayo.
Kwindibaniselwano nganye, kwenziwe iimvavanyo ezili-150 ukuze kufundwe isiphumo semvula yeCaCO3 kunye nokuvavanya izinto ezahlukeneyo, ezizezi: uxinano lomthombo wecalcium, ixesha lokuphilisa, ixabiso lebhaktiriya le-OD, umlinganiselo wesisombululo somthombo wecalcium kwibhaktiriya kunye ne-pH ngexesha le-aerobic oxidation yezinto eziphilayo (Itheyibhile 1). Uluhlu lwe-pH lwenkqubo ephuculweyo lukhethwe ngokusekelwe kwiikhompawundi zokukhula zeBacillus subtilis kunye neBacillus amyloliquefaciens ukuze kufunyanwe ukukhula ngokukhawuleza. Oku kuchazwe ngokweenkcukacha kwicandelo leZiphumo.
La manyathelo alandelayo asetyenzisiwe ukulungiselela iisampulu zesigaba sokwenza ngcono. Isisombululo se-MICP salungiswa kuqala ngokulungisa i-pH yokuqala yesixhobo sokukhulisa izityalo saza safakwa kwi-autoclave kwi-121 °C imizuzu eli-15. Emva koko uhlobo lwafakwa kwi-laminar air flow kwaye lwagcinwa kwi-shaking incubator kwi-30 °C kunye ne-180 rpm. Nje ukuba i-OD yebhaktheriya ifikelele kwinqanaba elifunekayo, yaxutywa nesisombululo somthombo we-calcium kwisilinganiso esifunekayo (Umfanekiso 1a). Isisombululo se-MICP savunyelwa ukuba siphendule kwaye siqine kwi-shaking incubator kwi-220 rpm kunye ne-30 °C ixesha elifikelele kwixabiso elijoliswe kulo. I-CaCO3 ekhawulezileyo yahlulwa emva kwe-centrifugation kwi-6000 g imizuzu emi-5 yaze yomiswa kwi-40 °C ukulungiselela iisampulu zovavanyo lwe-calcimeter (Umfanekiso 1b). Ukuna kweCaCO3 emva koko kwalinganiswa kusetyenziswa iBernard calcimeter, apho umgubo weCaCO3 usabela kwi-1.0 N HCl (ASTM-D4373-02) ukuvelisa i-CO2, kwaye umthamo wale gesi ngumlinganiselo womxholo weCaCO3 (Umfanekiso 1c). Ukuguqula umthamo weCO2 ube ngumxholo weCaCO3, kwenziwa i-calibration curve ngokuhlamba umgubo weCaCO3 ococekileyo one-1 N HCl kwaye uyidwebe ngokuchasene ne-CO2 eguqukileyo. Imo kunye nobunyulu bomgubo weCaCO3 ovuthuziweyo kuphandwe kusetyenziswa i-SEM imaging kunye nohlalutyo lwe-XRD. I-microscope ye-optical enobukhulu be-1000 yasetyenziswa ukufunda ukwakheka kwe-calcium carbonate ejikeleze iibhaktheriya, isigaba se-calcium carbonate eyenziweyo, kunye nomsebenzi webhaktheriya.
I-Dejegh Basin yindawo eyaziwayo ebole kakhulu kumzantsi-ntshona wePhondo laseFars e-Iran, kwaye abaphandi baqokelele iisampulu zomhlaba ezibole kakhulu kuloo ndawo. Iisampulu zithathwe kumphezulu womhlaba ukuze kwenziwe uphando. Uvavanyo lwezalathisi kwiisampulu zomhlaba lubonise ukuba umhlaba wawungahlelwanga kakuhle ngomhlaba onesihlabathi one-silt kwaye wahlulwa njenge-SP-SM ngokwe-Unified Soil Classification System (USC) (Umfanekiso 2a). Uhlalutyo lwe-XRD lubonise ukuba umhlaba we-Dejegh wawuquka ikakhulu i-calcite kunye ne-quartz (Umfanekiso 2b). Ukongeza, uhlalutyo lwe-EDX lubonise ukuba ezinye izinto ezifana ne-Al, K, kunye ne-Fe nazo zazikho ngomlinganiselo omncinci.
Ukulungiselela iindunduma zelabhoratri ukuvavanya ukukhukuliseka komoya, umhlaba watyunyuzwa ukusuka kubude be-170 mm nge-funnel enobubanzi be-10 mm ukuya kumphezulu oqinileyo, nto leyo eyabangela ukuba kubekho indunduma eqhelekileyo enobude be-60 mm kunye nobubanzi be-210 mm. Ngokwendalo, iindunduma zesanti ezinobunzima obuphantsi zenziwe ziinkqubo ze-aeolian. Ngokufanayo, isampuli elungiselelwe kusetyenziswa le nkqubo ingasentla yayinobunzima obuphantsi, i-γ = 14.14 kN/m³, nto leyo eyenza ikhowuni yesanti ebekwe kumphezulu othe tyaba one-engile yokuphumla emalunga ne-29.7°.
Isisombululo se-MICP esifanelekileyo esifunyenwe kwicandelo elidlulileyo sitshizwe kwithambeka leenduli ngesantya sokusetyenziswa se-1, 2 kunye ne-3 lm-2 kwaye emva koko iisampulu zigcinwe kwi-incubator kuma-30 °C (Umzobo 3) kangangeentsuku ezili-9 (oko kukuthi, ixesha elifanelekileyo lokunyanga) kwaye emva koko zithathwe ziye kuvavanywa imigudu yomoya.
Kunyango ngalunye, kwalungiselelwa iisampulu ezine, enye yokulinganisa umxholo we-calcium carbonate kunye namandla omphezulu kusetyenziswa i-penetrometer, kwaye ezinye iisampulu ezintathu eziseleyo zasetyenziselwa uvavanyo lokukhukuliseka ngesantya esithathu esahlukileyo. Kuvavanyo lwe-wind tunnel, ubungakanani bokukhukuliseka bumiselwe ngesantya somoya esahlukileyo, kwaye emva koko isantya sokuqhekeka komda kwisampulu nganye yonyango samiselwa kusetyenziswa iploti yobungakanani bokukhukuliseka ngokuchasene nesantya somoya. Ukongeza kuvavanyo lokukhukuliseka komoya, iisampulu eziphathweyo zafakwa kwi-sand bombardment (oko kukuthi, uvavanyo lokutsiba). Iisampulu ezimbini ezongezelelweyo zalungiselelwa le njongo ngesantya sokusetyenziswa se-2 kunye ne-3 L m−2. Uvavanyo lokuqhumisa isampulu lwathatha imizuzu eli-15 nge-flux ye-120 gm−1, engaphakathi koluhlu lwamaxabiso akhethwe kwizifundo zangaphambili60,61,62. Umgama othe tyaba phakathi kwe-abrasive nozzle kunye nesiseko se-dune yayiyi-800 mm, ebekwe kwi-100 mm ngaphezulu komzantsi we-tunnel. Le ndawo yabekwa ngendlela yokuba phantse zonke ii-stump sand particles ziwele kwi-dune.
Uvavanyo lwe-wind tunnel lwenziwe kwi-tunnel yomoya evulekileyo enobude obuyi-8 m, ububanzi obuyi-0.4 m kunye nokuphakama kwe-1 m (Umfanekiso 4a). I-wind tunnel yenziwe ngamashiti entsimbi agqunyiweyo kwaye inokuvelisa isantya somoya esifikelela kwi-25 m/s. Ukongeza, i-frequency converter isetyenziselwa ukulungisa i-fan frequency kunye nokunyusa i-frequency kancinci ukuze kufunyanwe isantya somoya ekujoliswe kuso. Umfanekiso 4b ubonisa umzobo we-schematic weendunduma zesanti ezikhukuliswe ngumoya kunye neprofayili yesantya somoya esilinganiswe kwi-wind tunnel.
Okokugqibela, ukuthelekisa iziphumo zefomyula ye-MICP engeyiyo i-urealytic ecetywayo kolu phononongo kunye neziphumo zovavanyo lolawulo lwe-MICP ye-urealytic, iisampulu zendunduma nazo zalungiswa zaza zanyangwa ngesisombululo sebhayoloji esine-urea, i-calcium chloride kunye ne-Sporosarcina pasteurii (ekubeni i-Sporosarcina pasteurii inamandla abalulekileyo okuvelisa i-urease63). Uxinano lwe-optical lwesisombululo sebhaktiriya yayiyi-1.5, kwaye uxinano lwe-urea kunye ne-calcium chloride yayiyi-1 M (ekhethwe ngokusekelwe kumaxabiso acetyisiweyo kwizifundo zangaphambili36,64,65). Indawo yokukhulisa yayinomhluzi wezondlo (8 g/L) kunye ne-urea (20 g/L). Isisombululo sebhaktiriya satshizwa kumphezulu wendunduma saza sashiywa iiyure ezingama-24 ukuze sinamathele kwibhaktiriya. Emva kweeyure ezingama-24 zokuncamathiselwa, isisombululo sokuqiniswa (i-calcium chloride kunye ne-urea) satshizwa. Uvavanyo lolawulo lwe-urealytic MICP lubizwa ngokuba yi-UMC. Umxholo we-calcium carbonate kwiisampuli zomhlaba eziphathwe nge-urealytic kunye ne-non-urealytically ufunyenwe ngokuhlanjwa ngokwenkqubo ecetyiswe nguChoi et al.66.
Umfanekiso 5 ubonisa ii-curves zokukhula kweBacillus amyloliquefaciens kunye neBacillus subtilis kwindawo yokulima (isisombululo sezakhamzimba) kunye noluhlu lokuqala lwe-pH oluyi-5 ukuya kwi-10. Njengoko kubonisiwe kumfanekiso, iBacillus amyloliquefaciens kunye neBacillus subtilis zikhule ngokukhawuleza kwi-pH 6-8 kunye ne-7-9, ngokulandelelana. Ke ngoko, olu luhlu lwe-pH lwamkelwe kwinqanaba lokuphucula.
Iikhribhu zokukhula ze-(a) Bacillus amyloliquefaciens kunye (b) Bacillus subtilis kwiixabiso ezahlukeneyo zokuqala ze-pH ze-medium yezakhamzimba.
Umfanekiso 6 ubonisa ubungakanani bekhabhoni diokside eveliswe kwiBernard limemeter, emele i-calcium carbonate ekhawulezileyo (CaCO3). Ekubeni enye into yayimiselwe kwindibaniselwano nganye kwaye ezinye izinto zahluka, inqaku ngalinye kwezi grafu lihambelana nomthamo ophezulu wekhabhoni diokside kuloo seti yovavanyo. Njengoko kubonisiwe kumfanekiso, njengoko uxinzelelo lomthombo wekhabhoni lukhula, ukuveliswa kwekhabhoni calcium kwanda. Ke ngoko, uxinzelelo lomthombo wekhabhoni luchaphazela ngokuthe ngqo ukuveliswa kwekhabhoni calcium. Ekubeni umthombo wekhabhoni kunye nomthombo wekhabhoni zifana (oko kukuthi, i-calcium formate kunye ne-calcium acetate), okukhona kukhululwa ii-ion zekhabhoni ezininzi, kokukhona kwakheka i-calcium carbonate eninzi (Umfanekiso 6a). Kwiifomyula ze-AS kunye ne-AA, ukuveliswa kwekhabhoni calcium kwaqhubeka nokwanda ngexesha lokukhula de inani lokukhula liphantse lingatshintshi emva kweentsuku ezili-9. Kwifomyula ye-FA, izinga lokwakheka kwekhabhoni calcium lehla xa ixesha lokukhula lidlula iintsuku ezi-6. Xa kuthelekiswa nezinye iifomyula, ifomyula ye-FS ibonise izinga lokwakheka kwekhabhoni calcium eliphantsi emva kweentsuku ezi-3 (Umfanekiso 6b). Kwimixube ye-FA kunye ne-FS, i-70% kunye ne-87% yemveliso iyonke ye-calcium carbonate ifunyenwe emva kweentsuku ezintathu, ngelixa kwimixube ye-AA kunye ne-AS, eli nani lalimalunga ne-46% kunye ne-45% kuphela, ngokulandelelana. Oku kubonisa ukuba imixube esekelwe kwi-formic acid inezinga eliphezulu lokwakheka kwe-CaCO3 kwinqanaba lokuqala xa kuthelekiswa nemixube esekelwe kwi-acetate. Nangona kunjalo, izinga lokwakheka liyehla ngokuhamba kwexesha lokunyuka kokuphilisa. Kungagqitywa kwiMifanekiso 6c ukuba nokuba kumanqanaba ebhaktheriya angaphezu kwe-OD1, akukho negalelo libalulekileyo ekubunjweni kwe-calcium carbonate.
Utshintsho kumthamo we-CO2 (kunye nomxholo we-CaCO3 ohambelanayo) olinganiswa yi-Bernard calcimeter njengomsebenzi we (a) uxinzelelo lomthombo we-calcium, (b) ixesha lokuseta, (c) i-OD, (d) i-pH yokuqala, (e) umlinganiselo womthombo we-calcium kwisisombululo sebhaktiriya (kwifomyula nganye); kunye (f) isixa esiphezulu se-calcium carbonate esiveliswayo kudibaniso ngalunye lomthombo we-calcium kunye nebhaktiriya.
Ngokuphathelele isiphumo se-pH yokuqala ye-medium, uMfanekiso 6d ubonisa ukuba kwi-FA kunye ne-FS, imveliso ye-CaCO3 ifikelele kwixabiso eliphezulu kwi-pH 7. Olu qwalaselo luhambelana nezifundo zangaphambili zokuba ii-enzymes ze-FDH zizinzile kakhulu kwi-pH 7-6.7. Nangona kunjalo, kwi-AA kunye ne-AS, imvula ye-CaCO3 yanda xa i-pH idlula i-7. Izifundo zangaphambili zikwabonise ukuba uluhlu lwe-pH olufanelekileyo lomsebenzi we-enzyme ye-CoA luqala kwi-8 ukuya kwi-9.2-6.8. Ukuqwalasela ukuba uluhlu lwe-pH olufanelekileyo lomsebenzi we-enzyme ye-CoA kunye nokukhula kwe-B. amyloliquefaciens yi-(8-9.2) kunye ne-(6-8), ngokulandelelana (Umfanekiso 5a), i-pH efanelekileyo yokwenziwa kwe-AA kulindeleke ukuba ibe yi-8, kwaye uluhlu lwe-pH ezimbini luyadibana. Le nyaniso iqinisekiswe zizilingo, njengoko kubonisiwe kuMfanekiso 6d. Ekubeni i-pH efanelekileyo yokukhula kwe-B. subtilis yi-7-9 (Umfanekiso 5b) kwaye i-pH efanelekileyo yomsebenzi we-enzyme ye-CoA yi-8-9.2, isivuno esiphezulu semvula ye-CaCO3 kulindeleke ukuba sibe kuluhlu lwe-pH lwe-8-9, oluqinisekiswa nguMfanekiso 6d (oko kukuthi, i-pH efanelekileyo yemvula yi-9). Iziphumo eziboniswe kuMfanekiso 6e zibonisa ukuba umlinganiselo ofanelekileyo wesisombululo somthombo we-calcium kwisisombululo sebhaktiriya yi-1 kwizisombululo ze-acetate kunye ne-formate. Ukuthelekisa, ukusebenza kweendlela ezahlukeneyo (oko kukuthi, i-AA, i-AS, i-FA, kunye ne-FS) kuhlolwe ngokusekelwe kwimveliso ephezulu ye-CaCO3 phantsi kweemeko ezahlukeneyo (oko kukuthi, uxinzelelo lomthombo we-calcium, ixesha lokuphilisa, i-OD, umlinganiselo wesisombululo somthombo we-calcium kwisisombululo sebhaktiriya, kunye ne-pH yokuqala). Phakathi kweendlela ezifundwe, i-formulation FS yayinemveliso ephezulu ye-CaCO3, eyayiphantse ibe kathathu kune-formulation AA (Umfanekiso 6f). Kwenziwe iimvavanyo ezine zokulawula ezingenabhaktiriya kuzo zombini imithombo ye-calcium kwaye akukho mvula ye-CaCO3 ebonwe emva kweentsuku ezingama-30.
Imifanekiso ye-optical microscopy yazo zonke ezi fomyula ibonise ukuba i-vaterite yayiyeyona nqanaba liphambili apho kwasekwa khona i-calcium carbonate (Umfanekiso 7). Iikristale ze-vaterite zaziyimilo eyi-spherical69,70,71. Kufunyaniswe ukuba i-calcium carbonate yayingena kwiiseli zebhaktiriya kuba umphezulu weeseli zebhaktiriya wawune-negative charge kwaye unokusebenza njenge-adsorbent ye-divalent cations. Ukuthatha i-formulation FS njengomzekelo kolu phononongo, emva kweeyure ezingama-24, i-calcium carbonate yaqala ukwakheka kwezinye iiseli zebhaktiriya (Umfanekiso 7a), kwaye emva kweeyure ezingama-48, inani leeseli zebhaktiriya ezigqunywe yi-calcium carbonate landa kakhulu. Ukongeza, njengoko kubonisiwe kuMfanekiso 7b, iinxalenye ze-vaterite nazo zafunyanwa. Ekugqibeleni, emva kweeyure ezingama-72, inani elikhulu leebhaktiriya labonakala libotshelelwe ziikristale ze-vaterite, kwaye inani leenxalenye ze-vaterite landa kakhulu (Umfanekiso 7c).
Ukujongwa kwe-optical microscopy kwe-CaCO3 precipitation kwi-FS compositions ngokuhamba kwexesha: (a) 24, (b) 48 kunye (c) 72 h.
Ukuze kuphandwe ngakumbi ngesimo sesigaba esichaphazekileyo, kwenziwe uhlalutyo lwe-X-ray diffraction (XRD) kunye ne-SEM yeempuphu. I-XRD spectra (Umzobo 8a) kunye nee-SEM micrographs (Umzobo 8b, c) ziqinisekisile ukubakho kweekristale ze-vaterite, njengoko zazinesimo esifana nelettuce kwaye kwabonwa ukungqinelana phakathi kweencochoyi ze-vaterite kunye neencochoyi ze-precipitate.
(a) Uthelekiso lwee-spectra ze-X-ray diffraction ze-CaCO3 eyenziweyo kunye ne-vaterite. Ii-micrographs ze-SEM ze-vaterite kwi-(b) 1 kHz kunye (c) nokwandiswa kwe-5.27 kHz, ngokulandelelana.
Iziphumo zovavanyo lwe-wind tunnel ziboniswe kuMfanekiso 9a, b. Kunokubonwa kuMfanekiso 9a ukuba isantya sokukhukuliseka komhlaba (TDV) wesanti enganyangwanga simalunga ne-4.32 m/s. Kwisantya sokusebenzisa se-1 l/m² (Umfanekiso 9a), imiqolo yemigca yokulahleka komhlaba kwiinxalenye ze-FA, FS, AA kunye ne-UMC iphantse ifane neyeendunduma ezinganyangwanga. Oku kubonisa ukuba unyango olukwesi santya sokusebenzisa alusebenzi kwaye kwangoko xa isantya somoya sidlula i-TDV, uqweqwe lomhlaba oluncinci luyanyamalala kwaye izinga lokukhukuliseka komhlaba liyafana neleendunduma ezinganyangwanga. I-slope yokukhukuliseka kwe-fraction AS nayo iphantsi kuneyezinye iinxalenye ezine-abscissas ezisezantsi (oko kukuthi i-TDV) (Umfanekiso 9a). Iintolo kuMfanekiso 9b zibonisa ukuba kwisantya somoya esiphezulu se-25 m/s, akukho kukhukuliseka kwenzeke kwiindunduma ezinyangwayo kwizinga lokusebenzisa ze-2 kunye ne-3 l/m². Ngamanye amazwi, kwi-FS, FA, AS kunye ne-UMC, iindunduma bezinokumelana ngakumbi nokukhukuliseka komoya okubangelwe kukubekwa kweCaCO³ kwizinga lokusetyenziswa le-2 kunye ne-3 l/m² kunakwisantya somoya esiphezulu (oko kukuthi, i-25 m/s). Ngoko ke, ixabiso le-TDV le-25 m/s elifunyenwe kwezi mvavanyo ngumda ophantsi wezinga lokusetyenziswa eliboniswe kuMfanekiso 9b, ngaphandle kwimeko ye-AA, apho i-TDV iphantse ilingane nesantya esiphezulu se-tunnel yomoya.
Uvavanyo lokukhukuliseka komoya (a) Ukwehla kobunzima xa kuthelekiswa nesantya somoya (isantya sokusetyenziswa yi-1 l/m2), (b) Isantya sokukrazula komgca xa kuthelekiswa nesantya sokusetyenziswa kunye nefomyula (i-CA ye-calcium acetate, i-CF ye-calcium formate).
Umfanekiso 10 ubonisa ukukhukuliseka komphezulu weendunduma zesanti eziphathwe ngeendlela ezahlukeneyo kunye namazinga okusetyenziswa emva kovavanyo lokuqhumisa isanti kwaye iziphumo zobungakanani ziboniswe kuMfanekiso 11. Ityala elinganyangwanga aliboniswanga kuba alibonisanga kuxhathisa kwaye lakhukuliseka ngokupheleleyo (ukulahleka kobunzima obupheleleyo) ngexesha lovavanyo lokuqhumisa isanti. Kucacile kuMfanekiso 11 ukuba isampuli ephathwe nge-biocomposition AA ilahlekelwe yi-83.5% yobunzima bayo ngesantya sokusetyenziswa se-2 l/m2 ngelixa zonke ezinye iisampulu zibonise ukukhukuliseka okungaphantsi kwe-30% ngexesha lenkqubo yokuqhumisa isanti. Xa izinga lokusetyenziswa lonyuswa ukuya kwi-3 l/m2, zonke iisampulu eziphathweyo zilahlekelwe ngaphantsi kwe-25% yobunzima bazo. Kuzo zombini izinga lokusetyenziswa, i-compound FS ibonise ukuxhathisa okungcono kakhulu kwi-sand bombardment. Ukuxhathisa okuphezulu kunye nokuncinci kwi-bombardment kwiisampulu eziphathwe yi-FS kunye ne-AA kunokubangelwa kukuchacha kwazo okuphezulu kunye nokuncinci kwe-CaCO3 (Umfanekiso 6f).
Iziphumo zokuqhushumba kweendunduma zesanti zemixholo eyahlukeneyo kwisantya sokuhamba kwe-2 kunye ne-3 l/m2 (iintolo zibonisa icala lomoya, iminqamlezo ibonisa icala lomoya elithe nkqo kwindiza yomzobo).
Njengoko kubonisiwe kuMfanekiso 12, umxholo we-calcium carbonate wazo zonke iifomyula unyuke njengoko izinga lokusetyenziswa linyuka ukusuka kwi-1 L/m² ukuya kwi-3 L/m². Ukongeza, kuzo zonke izinga lokusetyenziswa, ifomula enomxholo ophezulu we-calcium carbonate yayiyi-FS, ilandelwa yi-FA kunye ne-UMC. Oku kubonisa ukuba ezi fomula zinokuba nokumelana okuphezulu komphezulu.
Umfanekiso 13a ubonisa utshintsho ekuxhathiseni komhlaba kwiisampuli zomhlaba ezinganyangwanga, ezilawulwayo nezinyangiweyo ezilinganiswe ngovavanyo lwe-permeameter. Kulo mfanekiso, kuyacaca ukuba ukumelana komhlaba kweefomyula ze-UMC, AS, FA kunye ne-FS kwanda kakhulu ngokwanda kwesantya sokusetyenziswa. Nangona kunjalo, ukwanda kwamandla omphezulu kwakuncinci kwifomyula ye-AA. Njengoko kubonisiwe kumfanekiso, iifomyula ze-FA kunye ne-FS ze-MICP engaboliyo i-urea zinokungena okungcono komphezulu xa kuthelekiswa ne-MICP eboliyo i-urea. Umfanekiso 13b ubonisa utshintsho kwi-TDV ngokuxhathisa komphezulu womhlaba. Kulo mfanekiso, kuyacaca ukuba kwiindunduma ezinokumelana nomphezulu okungaphezulu kwe-100 kPa, isantya sokukrazula umda siya kudlula i-25 m/s. Ekubeni ukumelana nomphezulu kwindawo ethile kunokulinganiswa ngokulula nge-permeameter, olu lwazi lunokunceda ukuqikelela i-TDV xa kungekho vavanyo lwe-wind tunnel, ngaloo ndlela lusebenza njengesalathisi solawulo lomgangatho kwizicelo zasentsimini.
Iziphumo ze-SEM ziboniswe kuMfanekiso 14. Imifanekiso 14a-b ibonisa amasuntswana amakhulu esampuli yomhlaba enganyangwanga, nto leyo ebonisa ngokucacileyo ukuba ihambelana kwaye ayinabonda okanye i-cementation yendalo. Umfanekiso 14c ubonisa i-micrograph ye-SEM yesampuli yokulawula ephathwe nge-urea-degraded MICP. Lo mfanekiso ubonisa ubukho be-CaCO3 precipitates njenge-calcite polymorphs. Njengoko kuboniswe kuMfanekiso 14d-o, i-CaCO3 ekhawulezileyo ibopha amasuntswana kunye; iikristale ze-spherical vaterite zinokuchongwa nakwii-micrographs ze-SEM. Iziphumo zolu phononongo kunye nezifundo zangaphambili zibonisa ukuba amasuntswana e-CaCO3 enziwe njenge-vaterite polymorphs anokubonelela ngamandla afanelekileyo oomatshini; iziphumo zethu zibonisa ukuba ukumelana nomphezulu kuyanda ukuya kwi-350 kPa kwaye isantya sokwahlulwa komngcelele siyanda ukusuka kwi-4.32 ukuya ngaphezulu kwe-25 m/s. Esi siphumo sihambelana neziphumo zophando lwangaphambili zokuba i-matrix ye-MICP-precipitated CaCO3 yi-vaterite, enamandla oomatshini afanelekileyo kunye nokumelana nokukhukuliseka komoya13,40 kwaye inokugcina ukumelana nokukhukuliseka komoya okufanelekileyo nasemva kweentsuku ezili-180 zokuchatshazelwa yimeko yendawo yasentsimini13.
(a, b) Ii-micrograph ze-SEM zomhlaba onganyangwanga, (c) Ulawulo lokonakala kwe-urea ye-MICP, (df) Iisampulu eziphathwe nge-AA, (gi) Iisampulu eziphathwe nge-AS, (jl) Iisampulu eziphathwe nge-FA, kunye (mo) Iisampulu eziphathwe nge-FS ngesantya sokusetyenziswa se-3 L/m2 kwiindlela ezahlukeneyo zokukhulisa.
Umfanekiso 14d-f ubonisa ukuba emva konyango ngee-AA compounds, i-calcium carbonate yangena phezu komhlaba naphakathi kwee-sand grains, ngelixa ezinye ii-sand grains ezingagqunywanga nazo zabonwa. Kwizinto ze-AS, nangona ubungakanani be-CaCO3 obubunjiweyo bungazange bunyuke kakhulu (Umfanekiso 6f), ubungakanani boqhagamshelwano phakathi kwee-sand grains ezibangelwa yi-CaCO3 bunyuke kakhulu xa kuthelekiswa nee-AA compounds (Umfanekiso 14g-i).
Ukusuka kwiMifanekiso 14j-l kunye ne-14m-o kuyacaca ukuba ukusetyenziswa kwe-calcium formate njengomthombo we-calcium kukhokelela ekwandeni okungakumbi kwemvula ye-CaCO3 xa kuthelekiswa ne-AS compound, ehambelana nokulinganiswa kwe-calcium meter kuMfanekiso 6f. Le CaCO3 eyongezelelweyo ibonakala ibekwe ikakhulu kumasuntswana esanti kwaye ayiphuculi umgangatho woqhagamshelwano. Oku kuqinisekisa ukuziphatha okubonwe ngaphambili: nangona kukho umahluko kubungakanani bemvula ye-CaCO3 (Umfanekiso 6f), iifomyula ezintathu (AS, FA kunye ne-FS) azihlukanga kakhulu ngokubhekiselele ekusebenzeni kwe-anti-eolian (umoya) (Umfanekiso 11) kunye nokumelana nomphezulu (Umfanekiso 13a).
Ukuze kubonwe ngcono iiseli zebhaktiriya ezigqunywe yiCaCO3 kunye nophawu lwebhaktiriya kwiikristale ezivuthulukileyo, kuthathwe ii-micrographs ze-SEM ezikhulisa kakhulu kwaye iziphumo ziboniswe kuMfanekiso 15. Njengoko kubonisiwe, i-calcium carbonate ivuthuluka kwiiseli zebhaktiriya kwaye ibonelela ngeenuclei ezifunekayo ukuze kuvuthuluke apho. Lo mfanekiso ukwabonisa unxibelelwano olusebenzayo nolungasebenziyo olubangelwa yiCaCO3. Kungagqitywa kwelokuba naluphi na ukwanda konxibelelwano olungasebenziyo akuthethi ukuba kukhokelele ekuphuculeni ngakumbi kwindlela yokuziphatha koomatshini. Ke ngoko, ukwandisa imvula yeCaCO3 akuthethi ukuba kukhokelele kumandla aphezulu oomatshini kwaye ipatheni yemvula idlala indima ebalulekileyo. Eli nqaku likwafundwe kwimisebenzi kaTerzis noLaloui72 kunye noSoghi no-Al-Kabani45,73. Ukuze kuhlolwe ngakumbi ubudlelwane phakathi kwepatheni yemvula kunye namandla oomatshini, kucetyiswa izifundo zeMICP ezisebenzisa umfanekiso we-µCT, okungaphaya kobubanzi bolu phononongo (oko kukuthi, ukwazisa indibaniselwano eyahlukeneyo yomthombo we-calcium kunye neebhaktiriya kwi-MICP engena-ammonia).
I-CaCO3 ibangele iibhondi ezisebenzayo nezingasebenziyo kwiisampuli eziphathwe nge (a) ukwakheka kwe-AS kunye (b) ukwakheka kwe-FS kwaye yashiya uphawu lweeseli zebhaktiriya kwi-sediment.
Njengoko kubonisiwe kwiMifanekiso 14j-o kunye ne-15b, kukho ifilimu yeCaCO (ngokohlalutyo lwe-EDX, ukwakheka kwepesenti yento nganye kwifilimu yikhabhoni 11%, ioksijini 46.62% kunye necalcium 42.39%, esondele kakhulu kwipesenti yeCaCO kuMfanekiso 16). Le filimu igubungela iikristale zevaterite kunye namasuntswana omhlaba, inceda ukugcina ukuthembeka kwenkqubo ye-sediment yomhlaba. Ubukho bale filimu bubonwe kuphela kwiisampuli eziphathwe ngefomate-based formulation.
Itheyibhile 2 ithelekisa amandla omphezulu, isantya sokuqhekeka komda, kunye nomxholo we-CaCO3 obangelwa yi-bioinduced wemihlaba ephathwe ngeendlela ze-MICP ezibolayo ze-urea kunye ne-non-urea-degrading kwizifundo zangaphambili kunye nolu phononongo. Izifundo malunga nokuxhathisa ukukhukuliseka komoya kweesampuli ze-dune eziphathwe nge-MICP zinqongophele. UMeng et al. uphande ukuxhathisa ukukhukuliseka komoya kweesampuli ze-dune ezibolayo ze-urea eziphathwe nge-MICP besebenzisa isixhobo sokuvuthela amagqabi,13 ngelixa kolu phononongo, iisampuli ze-dune ezibolayo ze-urea (kunye nolawulo lokubola kwe-urea) zavavanywa kwi-tunnel yomoya kwaye zanyangwa ngemixube emine eyahlukeneyo yebhaktheriya kunye nezinto.
Njengoko kunokubonwa, ezinye izifundo zangaphambili ziqwalasele amazinga aphezulu okusetyenziswa angaphezulu kwe-4 L/m213,41,74. Kubalulekile ukuqaphela ukuba amazinga aphezulu okusetyenziswa asenokungabi lula kwicandelo ngokwembono yezoqoqosho ngenxa yeendleko ezinxulumene nokunikezelwa kwamanzi, ukuthuthwa kunye nokusetyenziswa kwamanzi amaninzi. Amanqanaba aphantsi okusetyenziswa anjenge-1.62-2 L/m2 nawo afumene amandla amahle omphezulu afikelela kwi-190 kPa kunye ne-TDV angaphezulu kwe-25 m/s. Kolu phononongo, iindunduma eziphathwe nge-formate-based MICP ngaphandle kokonakala kwe-urea zifumene amandla aphezulu omphezulu afana nalawo afunyenwe ngendlela yokonakala kwe-urea kuluhlu olufanayo lwamazinga okusetyenziswa (oko kukuthi, iisampulu eziphathwe nge-formate-based MICP ngaphandle kokonakala kwe-urea nazo zikwazile ukufikelela kuluhlu olufanayo lwamaxabiso amandla omphezulu njengoko kubikwe nguMeng et al., 13, Umfanekiso 13a) kumanqanaba aphezulu okusetyenziswa. Kwakhona kunokubonwa ukuba kwisantya sokusetyenziswa se-2 L/m2, isivuno se-calcium carbonate sokunciphisa ukukhukuliseka komoya kwisantya somoya se-25 m/s yayiyi-2.25% kwi-MICP esekelwe kwi-formate ngaphandle kokudilizwa kwe-urea, nto leyo esondele kakhulu kwisixa esifunekayo se-CaCO3 (oko kukuthi, i-2.41%) xa kuthelekiswa neendunduma eziphathwe nge-MICP yolawulo kunye nokudilizwa kwe-urea kwisantya sokusetyenziswa esifanayo kunye nesantya somoya esifanayo (25 m/s).
Ngoko ke, kunokugqitywa kule theyibhile ukuba zombini indlela yokubola kwe-urea kunye nendlela yokubola engena-urea zinokubonelela ngokusebenza okwamkelekileyo ngokwemeko yokuxhathisa umphezulu kunye ne-TDV. Umahluko ophambili kukuba indlela yokubola engena-urea ayinayo i-ammonia kwaye ngenxa yoko inempembelelo ephantsi kwindalo esingqongileyo. Ukongeza, indlela ye-MICP esekelwe kwi-formate ngaphandle kokubola kwe-urea ecetywayo kolu phononongo ibonakala isebenza ngcono kunendlela ye-MICP esekelwe kwi-acetate ngaphandle kokubola kwe-urea. Nangona uMohebbi et al. efunde indlela ye-MICP esekelwe kwi-acetate ngaphandle kokubola kwe-urea, uphando lwabo luquke iisampulu kwiindawo ezithe tyaba9. Ngenxa yezinga eliphezulu lokubola okubangelwa kukwakheka kwe-eddy ejikeleze iisampulu ze-dune kunye ne-shear ephumayo, ekhokelela kwi-TDV ephantsi, ukubola komoya kwesampulu ze-dune kulindeleke ukuba kubonakale ngakumbi kunoko kwiindawo ezithe tyaba ngesantya esifanayo.