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Ke ƒe ahomwo nye afɔku gã aɖe na dukɔ geɖe le xexeame godoo le ŋusẽ gbegblẽ si wòkpɔna ɖe agbledede, amegbetɔ ƒe lãmesẽ, ʋuɖoɖo ƒe mɔnuwo kple xɔtuɖaŋuwo dzi ta. Esia wɔe be wobua ya ƒe ʋuʋu be enye xexeame katã ƒe kuxi. Mɔnu siwo gblẽa nu le nutome ŋu be woatsɔ axe mɔ ɖe ya ƒe ʋuʋu nu dometɔ ɖekae nye nugbagbevi suesuewo ƒe carbonate precipitation (MICP) zazã. Gake nusiwo dona tso MICP si wotu ɖe urea ƒe gbegblẽ dzi, abe amonia ene, mesɔ nyuie ne wowɔ wo le agbɔsɔsɔ gã me o. Numekuku sia tsɔ calcium formate dɔlékui ƒe wɔwɔme eve ɖo ŋkume hena MICP ƒe gbegblẽ evɔ womewɔa urea o eye wòtsɔ woƒe dɔwɔwɔ sɔ kple calcium acetate dɔlékui siwo mewɔa amonia o ƒe wɔwɔme eve bliboe. Dɔlékui siwo ŋu wobu enye Bacillus subtilis kple Bacillus amyloliquefaciens. Gbã la, wokpɔ nusiwo kpɔa ŋusẽ ɖe CaCO3 ƒe wɔwɔ dzi ƒe asixɔxɔ siwo sɔ nyuie wu. Emegbe wowɔ yaƒoƒo ƒe mɔ̃ dodokpɔwo le ke ƒe kpɔɖeŋu siwo ŋu wotsɔ atike siwo wowɔ nyuie wu la ŋu, eye wodzidze ya ƒe ʋuʋu ƒe tsitretsitsi, stripping threshold velocity, kple ke ƒe bɔmbdada ƒe tsitretsitsi. Wozã ŋkumekpɔmɔ̃, elektrɔnik nusuekpɔmɔ̃ (SEM), kple X-ray diffraction analysis tsɔ da calcium carbonate (CaCO3) allomorphs kpɔ. Atike siwo wotu ɖe calcium formate dzi wɔ dɔ nyuie wu atike siwo wotu ɖe acetate dzi le calcium carbonate wɔwɔ gome. Tsɔ kpe ɖe eŋu la, B. subtilis wɔ calcium carbonate geɖe wu B. amyloliquefaciens. SEM nusuekpɔmɔ̃wo ɖe dɔlékui siwo le dɔ wɔm kple esiwo mele dɔ wɔm o ƒe kadodo kple woƒe nuŋɔŋlɔ ɖe calcium carbonate dzi si tso tsiƒuƒu gbɔ fia kɔte. Atikeawo katã ɖe ya ƒe ʋuʋu dzi kpɔtɔ ŋutɔ.
Wode dzesii tso gbaɖegbe ke be ya ƒe ʋuʋu nye kuxi gã aɖe si dze ŋgɔ nuto siwo me tsi medzana le o kple esiwo me tsi medzana le o abe United States ƒe dzigbeɣetoɖoƒe, China ƒe ɣetoɖoƒe, Sahara Afrika, kple Titina Ɣedzeƒe ƒe akpa gãtɔ1. Tsidzadza si mebɔ o le yame ƒe nɔnɔme kuɖiɖi kple kuɖiɖi si gbɔ eme na nuto siawo ƒe akpa gãwo trɔ zu dzogbewo, kewo, kple anyigba siwo dzi womede agble ɖo o. Ya ƒe ʋuʋu si yi edzi la hea nutome ƒe afɔku vɛ na xɔtuɖoɖowo abe ʋuɖoɖo ƒe mɔnuwo, agbledenyigbawo, kple dɔwɔƒewo ƒe anyigba, si hea agbenɔnɔ ƒe nɔnɔme madeamedziwo kple dugãwo ƒe ŋgɔyiyi ƒe gazazã gãwo vɛ le nuto siawo me2,3,4. Vevietɔ la, menye ɖeko ya ƒe ʋuʋu gblẽa nu le teƒe si wòdzɔna le ko o, ke ehea lãmesẽ kple ganyawo ƒe kuxiwo hã vɛ le nuto siwo le didiƒe ʋĩ me elabena etsɔa nusuewo to ya me yia teƒe siwo didi tso dzɔtsoƒea gbɔ5,6.
Ya ƒe ʋuʋu dzi ɖuɖu gakpɔtɔ nye xexeame katã ƒe kuxi. Wozãa mɔnu vovovo siwo dzi woato ana anyigba nali ke tsɔ léa ya ƒe ʋuʋu nu. Mɔnu siawo dometɔ aɖewoe nye nusiwo le abe tsi zazã7, ami ƒe ʋeʋẽ8, biopolymers5, microbial induced carbonate precipitation (MICP)9,10,11,12 kple enzyme induced carbonate precipitation (EICP)1. Anyigba ƒe tsidede nye mɔnu si wozãna ɖaa tsɔ tsia ke nu le agble me. Ke hã, eƒe yaƒoƒo kabakaba na be mɔnu sia mewɔa dɔ nyuie le nuto siwo me tsi medzana le o kple esiwo me tsi medzana le o me o1. Ami ƒe ʋeʋẽ ƒe atikewo zazã nana ke ƒe ɖekawɔwɔ kple nusuewo dome ʋuʋu dzina ɖe edzi. Woƒe ɖekawɔwɔ ƒe nɔnɔme blaa kekuwo ɖe wo nɔewo ŋu; ke hã, amisisiwo hã hea kuxi bubuwo vɛ; woƒe amadede ɣia nana dzoxɔxɔ ƒe xɔxlɔ̃ dzina ɖe edzi eye wònana numiemiewo kple nugbagbevi suewo kuna. Woƒe ʋeʋẽ kple dzudzɔ ate ŋu ahe gbɔgbɔtsixetsixe vɛ, eye vevietɔ wu la, woƒe asixɔxɔ gã nye mɔxenu bubu. Biopolymers nye mɔnu siwo wodo ɖa nyitsɔ laa be woatsɔ aɖe ya ƒe ʋuʋu dzi akpɔtɔ si me gblẽa nu le nutome ŋu o la dometɔ ɖeka; woɖea wo tso dzɔdzɔmenuwo abe numiemiewo, lãwo kple dɔlékuiwo ene me. Xanthan gum, guar gum, chitosan kple gellan gum ye nye biopolymers siwo wozãna wu le mɔ̃ɖaŋudɔwo me5. Ke hã, biopolymers siwo me tsi le ate ŋu abu ŋusẽ eye woaɖe wo ɖa le anyigba me ne wodo wo ɖe tsi me13,14. Woɖee fia be EICP nye ke nutsitsi mɔnu nyui aɖe na dɔ vovovowo wɔwɔ siwo dometɔ aɖewoe nye mɔ siwo womeɖo o, tsita siwo me woɖea tsi le kple xɔtuƒewo. Togbɔ be eƒe emetsonuwo de dzi ƒo hã la, ele be woabu nusiwo ate ŋu agblẽ nu le ame ŋu dometɔ aɖewo ŋu, abe gazazã kple nucleation teƒewo ƒe anyimanɔmanɔ (si naa CaCO3 kristalo ƒe wɔwɔme kple tsidzadza kabakaba15,16).
Murray kple Irwin (1890) kple Steinmann (1901) ye ƒo nu tso MICP ŋu zi gbãtɔ le woƒe numekuku le urea ƒe gbegblẽ to ƒumelã suewo dzi17 me. MICP nye nugbagbewo ƒe dɔwɔwɔ si dzɔna le dzɔdzɔme nu si me nugbagbevi suewo ƒe dɔwɔna vovovowo kple atikewɔmɔnu siwo me calcium carbonate dona le to carbonate ions siwo tso nugbagbevi suewo ƒe metabolites me ƒe dɔwɔwɔ kple calcium ions le nutoa me me18,19. MICP si me urea-gblẽa nitrogen ƒe tsatsam (urea-gblẽa MICP) nye carbonate ƒe tsidzadza si nugbagbevi suesuesuewo hena vɛ si bɔ wu, si me urease si dɔlékuiwo wɔna naa urea ƒe tsi me ʋuʋu20,21,22,23,24,25,26,27 abe alesi gbɔna ene:
Le MICP si me carbon cycle of organic salt oxidation (MICP si me urea ƒe gbegblẽ ƒomevi mele o) me la, heterotrophic dɔlékuiwo zãa organic salts abe acetate, lactate, citrate, succinate, oxalate, malate kple glyoxylate abe ŋusẽtsoƒewo ene tsɔ wɔa carbonate minerals28. Le calcium lactate abe carbon dzɔtsoƒe kple calcium ions ƒe anyinɔnɔ me la, woɖe atikewo ƒe dɔwɔwɔ le calcium carbonate wɔwɔ me fia le sɔsɔŋuɖoɖo (5) me.
Le MICP ƒe dɔwɔwɔ me la, dɔlékui ƒe lãmenugbagbeviwo naa nucleation teƒe siwo le vevie ŋutɔ na calcium carbonate ƒe tsidzadza; dɔlékui ƒe lãmenugbagbeviwo ƒe anyime xɔ dzo eye ate ŋu awɔ dɔ abe nusi xɔa cations divalent abe calcium ions ene. To calcium ions ƒe xɔxlɔ̃ ɖe dɔlékui ƒe lãmenugbagbeviwo dzi me la, ne carbonate ion ƒe agbɔsɔsɔme sɔ gbɔ la, calcium cations kple carbonate anions wɔa dɔ eye calcium carbonate ƒua du ɖe dɔlékui ƒe anyigba dzi29,30. Woate ŋu aƒo nu tso alesi wowɔa dɔe ŋu kpuie ale31,32:
Woate ŋu ama calcium carbonate kristalo siwo wowɔ le nugbagbewo me ɖe hatsotso etɔ̃ me: calcite, vaterite, kple aragonite. Le wo dome la, calcite kple vaterite ye nye calcium carbonate allomorphs siwo dɔlékuiwo hena vɛ wu33,34. Calcite ye nye dzoxɔxɔŋusẽ si li ke wu le calcium carbonate allomorph35 me. Togbɔ be woka nya ta be vaterite te ŋu kakana hã la, etrɔna zua calcite mlɔeba36,37. Vaterite ye nye kristalo siawo siwo me ʋeʋẽ lilili le wu. Enye kristalo si le dzogoe ade me si ƒe ʋuʋudedi yɔyɔ ƒe ŋutete nyo wu calcium carbonate kristalo bubuwo le eƒe lolome si lolo ta38. MICP si me urea gblẽ kple esi me urea megblẽ o siaa ateŋu ahe vaterite ƒe tsidzadza vɛ13,39,40,41.
Togbɔ be MICP ɖe ŋutete si ŋugbe wodo fia le anyigba siwo me kuxiwo le kple anyigba siwo te ŋu xɔa ya ƒe ʋuʋu bɔbɔe la li ke me hã la42,43,44,45,46,47,48 hã la, urea ƒe tsi ƒe ʋuʋu ƒe akpa aɖewo dometɔ ɖekae nye ammonia, si ate ŋu ahe lãmesẽkuxi fafɛ va ɖo sesẽ vɛ le alesi gbegbe wòxɔe nu49. Nugbegblẽ sia nana woʋlia nya le mɔ̃ɖaŋununya sia koŋ zazã ŋu, vevietɔ ne ehiã be woawɔ atike na teƒe gãwo, abe ke ene. Tsɔ kpe ɖe eŋu la, womate ŋu ado dzi atsɔ amonia ƒe ʋeʋẽ ne wowɔ dɔa le agbɔsɔsɔ gã me kple agbɔsɔsɔ gã me o, si ate ŋu akpɔ ŋusẽ ɖe eƒe zazã ŋutɔŋutɔ dzi. Togbɔ be numekuku siwo wowɔ nyitsɔ laa ɖee fia be woate ŋu aɖe ammonium ions dzi akpɔtɔ ne wotrɔ wo woazu nu bubuwo abe struvite ene hã la, mɔnu siawo meɖea ammonium ions ɖa keŋkeŋ o50. Eyata egahiã kokoko be woaku egbɔkpɔnu bubu siwo mewɔa ammonium ions o la me. Mɔ siwo menye urea ƒe gbegblẽ o zazã na MICP ate ŋu ana egbɔkpɔnu si ate ŋu anɔ anyi si ŋu womeku nu me le nyuie le ya ƒe ʋuʋu dzi ɖeɖe kpɔtɔ ƒe nyawo me o. Fattahi kple exɔlɔ̃wo. ku nu me le MICP ƒe gbegblẽ si me urea mele o ŋu to calcium acetate kple Bacillus megaterium41 zazã me, esime Mohebbi et al. wozã calcium acetate kple Bacillus amyloliquefaciens9. Gake wometsɔ woƒe numekukua sɔ kple calcium dzɔtsoƒe bubuwo kple heterotrophic dɔlékui siwo ate ŋu ana ya ƒe ʋuʋu ƒe tsitretsitsi nanyo ɖe edzi mlɔeba o. Agbalẽ siwo tsɔ urea-manɔmee ƒe gbegblẽmɔwo sɔ kple urea ƒe gbegblẽmɔwo le ya ƒe ʋuʋu dzi ɖeɖe kpɔtɔ me hã meli o.
Gakpe ɖe eŋu la, wowɔ ya ƒe ʋuʋu kple ke dzi ɖuɖu ŋuti numekuku akpa gãtɔ le anyigba ƒe kpɔɖeŋu siwo ƒe anyigba le gbadzaa ŋu.1,51,52,53 Ke hã, anyigba gbadzawo mebɔ ɖe dzɔdzɔme nu o wu togbɛwo kple togbɛwo. Esia tae kekuiwoe nye anyigba ƒe nɔnɔme si bɔ wu le dzogbenutowo me ɖo.
Be woaɖu gbɔdzɔgbɔdzɔ siwo míeyɔ ɖe etame dzi la, numekuku sia ƒe taɖodzinue nye be woato dɔlékui siwo mewɔa amonia o ƒe hatsotso yeye aɖe vɛ. Le esia ta la, míebu MICP mɔ siwo me urea gblẽa nu le o ŋu. Woku nu me le calcium dzɔtsoƒe eve (calcium formate kple calcium acetate) ƒe dɔwɔwɔ nyuie ŋu. Le agbalẽŋlɔlawo ƒe sidzedze nu la, womeku nu me le carbonate ƒe tsidzadza ŋu to calcium dzɔtsoƒe kple dɔlékui eve siwo wotsɔ ƒo ƒui zazã me (si nye calcium formate-Bacillus subtilis kple calcium formate-Bacillus amyloliquefaciens) le numekuku siwo wowɔ va yi me o. Wotu dɔlékui siawo ƒe tiatia ɖe enzyme siwo wowɔna siwo nana calcium formate kple calcium acetate ƒe oxidation wɔa dɔ tsɔ wɔa nugbagbevi suesuewo ƒe carbonate ƒe tsidzadza dzi. Míewɔ dodokpɔ ŋuti numekuku deto aɖe be míake ɖe nusiwo nyo wu abe pH, dɔlékui ƒomeviwo kple calcium dzɔtsoƒewo kple woƒe agbɔsɔsɔ, dɔlékuiwo ƒe sɔsɔme kple calcium dzɔtsoƒe ƒe tsi kple ɣeyiɣi si woatsɔ awɔ dɔe. Mlɔeba la, woku nu me le dɔlékuiwutikewo ƒe hatsotso sia ƒe dɔwɔwɔ nyuie le ya ƒe ʋuʋu nu tete to calcium carbonate ƒe tsidzadza me to yaƒoƒo ƒe mɔ̃ dodokpɔ vovovowo wɔwɔ ɖe ke ƒe togbɛwo dzi be woatsɔ anya ya ƒe ʋuʋu ƒe lolome, threshold breakaway velocity kple ya ƒe bɔmbdada ƒe tsitretsitsi ɖe kea ŋu, kple penetrometer dzidzedzewo kple microstructural numekukuwo (le kpɔɖeŋu me, X-ray diffraction (XRD) kple scanning wowɔ elektrɔnik nusuekpɔmɔ̃ (SEM)) hã.
Calcium carbonate wɔwɔ bia be calcium ions kple carbonate ions. Woateŋu akpɔ calcium ions tso calcium dzɔtsoƒe vovovowo abe calcium chloride, calcium hydroxide, kple notsi babla si womeɖe o me54,55. Woateŋu awɔ carbonate ions to nugbagbevi suewo ƒe mɔnu vovovowo abe urea hydrolysis kple aerobic alo anaerobic oxidation of organic matter56. Le numekuku sia me la, wokpɔ carbonate ions tso formate kple acetate ƒe oxidation reaction me. Tsɔ kpe ɖe eŋu la, míezã calcium dze siwo nye formate kple acetate tsɔ wɔ calcium carbonate dzadzɛ, eyata CO2 kple H2O koe míekpɔ abe nusiwo wotsɔ kpe ɖe eŋu ene. Le esia wɔwɔ me la, nu ɖeka koe wɔa dɔ abe calcium dzɔtsoƒe kple carbonate dzɔtsoƒe ene, eye womewɔa amonia aɖeke o. Nɔnɔme siawo na be calcium dzɔtsoƒe kple carbonate wɔwɔ ƒe mɔnu si míebu be edo ŋugbe ŋutɔ.
Woɖe alesi calcium formate kple calcium acetate wɔa dɔe si sɔ be woawɔ calcium carbonate la fia le mɔfiame (7)-(14) me. Mɔfiame (7)-(11) ɖee fia be calcium formate ʋẽna le tsi me wòzua formic acid alo formate. Eyata tsi si woɖe tso eme la nye calcium kple hydroxide ions siwo le ablɔɖe me (mɔ̃ɖaŋu 8 kple 9) ƒe dzɔtsoƒe. Le formic acid ƒe oxidation ta la, carbon atɔm siwo le formic acid me trɔna zua carbon dioxide (formula 10). Calcium carbonate va dzɔna mlɔeba (mɔfiame 11 kple 12).
Nenema ke wowɔa calcium carbonate tso calcium acetate me (sɔsɔ 13–15), negbe ɖeko acetic acid alo acetate dzɔna ɖe formic acid teƒe.
Ne enzymewo meli o la, womate ŋu awɔ oxidation le acetate kple formate me le xɔme ƒe dzoxɔxɔ nu o. FDH (formate dehydrogenase) kple CoA (coenzyme A) naa formate kple acetate ƒe oxidation wɔa carbon dioxide, ɖe wo nɔewo yome (Eqs. 16, 17) 57, 58, 59. Dɔlékui vovovowo te ŋu wɔa enzyme siawo, kple heterotrophic dɔlékui, si nye Bacillus subtilis (PTCC #1204 (Persian Type Wozã Dekɔnuwo Nuƒoƒoƒu), si woyɔna hã be NCIMB #13061 (Dukɔwo Dome Dɔlékuiwo, Amɔwɔʋãnu, Phage, Plasmidwo, Numiemiewo ƒe Nukuwo Kple Numiemiewo ƒe Lãmenugbagbeviwo ƒe Dekɔnuwo Nuƒoƒoƒu)) kple Bacillus amyloliquefaciens (PTCC #1732, NCIMB #12077), le numekuku sia me. Wode dɔlékui siawo le nusi me lã peptone (5 g/L) kple lã si woɖe tso lã me (3 g/L), si woyɔna be nunyiame ƒe ʋeʋẽ (NBR) (105443 Merck) le me.
Eyata wowɔ atike ene be woatsɔ ahe calcium carbonate ƒe tsidzadza vɛ to calcium dzɔtsoƒe eve kple dɔlékui eve zazã me: calcium formate kple Bacillus subtilis (FS), calcium formate kple Bacillus amyloliquefaciens (FA), calcium acetate kple Bacillus subtilis (AS), kple calcium acetate kple Bacillus amyloliquefaciens (AA).
Le dodokpɔa ƒe akpa gbãtɔ me la, wowɔ dodokpɔwo be woatsɔ anya nusiwo wotsɔ ƒo ƒui nyuitɔ kekeake si ana woakpɔ calcium carbonate si sɔ gbɔ wu. Esi wònye be calcium carbonate le anyigba ƒe kpɔɖeŋuawo me ta la, wowɔ dodokpɔ gbãtɔ siwo wowɔ tsɔ dzidzea CaCO3 si wowɔ to ƒuƒoƒo vovovoawo me la nyuie, eye woda dekɔnu me tsi kple calcium dzɔtsoƒe ƒe tsi siwo wotsaka kpɔ. Le calcium dzɔtsoƒe kple dɔlékui ƒe tsi ƒe ƒuƒoƒo ɖesiaɖe si míeɖe ɖe go le etame (FS, FA, AS, kple AA) gome la, wokpɔ nusiwo ana wowɔa dɔ nyuie wu (calcium dzɔtsoƒe ƒe agbɔsɔsɔ, ɣeyiɣi si wòda gbe le eŋu, dɔlékui ƒe tsi ƒe agbɔsɔsɔme si wodzidze to tsia ƒe nukpɔkpɔ ƒe kpekpeme (OD), calcium dzɔtsoƒe kple dɔlékui ƒe tsi ƒe sɔsɔme, kple pH) eye wozãe le yaƒoƒo ƒe mɔ̃ dodokpɔ siwo wowɔ le ke ƒe dɔwɔwɔ me si ŋu woƒo nu tsoe le akpa siwo gbɔna me.
Le ƒuƒoƒo ɖesiaɖe gome la, wowɔ dodokpɔ 150 tsɔ srɔ̃ nu tso CaCO3 ƒe tsidzadza ƒe ŋusẽkpɔɖeamedzi ŋu eye woda nu vovovowo kpɔ, siwo nye calcium dzɔtsoƒe ƒe agbɔsɔsɔ, dɔyɔɣi, dɔlékui ƒe OD ƒe asixɔxɔ, calcium dzɔtsoƒe kple dɔlékui ƒe tsi ƒe sɔsɔme kple pH le aerobic oxidation of organic matter me (Tabla 1). Wonɔ te ɖe Bacillus subtilis kple Bacillus amyloliquefaciens ƒe tsitsi ƒe fliwo dzi tia pH ƒe didime na ɖoɖo si wowɔ nyuie wu be woakpɔ tsitsi kabakaba. Woɖe esia me tsitotsito le Emetsonuwo ƒe akpaa dzi.
Wozã afɔɖeɖe siwo gbɔna tsɔ dzra kpɔɖeŋuawo ɖo na optimization phase la. Wodzra MICP solution la ɖo gbã to asitɔtrɔ le pH gbãtɔ si le dekɔnu me eye emegbe wotsɔe de autoclave me le 121 °C hena miniti 15. Emegbe wodoa ƒomevi la ɖe ya si sina toa laminar me eye wolénɛ ɖe te le vidzidɔ si le ʋuʋum me le dzoxɔxɔ 30 °C kple 180 rpm me. Ne dɔlékuiawo ƒe OD nya ɖo afisi wodi ko la, wotsakae kple calcium dzɔtsoƒe ƒe tsi le agbɔsɔsɔ si wodi me (Nɔnɔmetata 1a). Woɖe mɔ na MICP ƒe tsi la be wòawɔ dɔ eye wòasẽ le ʋuʋudedi si le ʋuʋum me le 220 rpm kple 30 °C me hena ɣeyiɣi si ɖo asixɔxɔ si woɖo be wòaɖo. Woɖe CaCO3 si ƒo ɖi la ɖe vovo le centrifugation megbe le 6000 g hena miniti 5 eye emegbe wotsɔe ƒu gbe le 40 °C tsɔ dzra kpɔɖeŋuawo ɖo na calcimeter dodokpɔ (Nɔnɔmetata 1b). Emegbe wozã Bernard calcimeter tsɔ dzidze CaCO3 ƒe tsidzadza, afisi CaCO3 ƒe aŋɔ wɔa dɔ kple 1.0 N HCl (ASTM-D4373-02) tsɔ wɔa CO2, eye gas sia ƒe lolome nye CaCO3 ƒe agbɔsɔsɔ ƒe dzidzenu (Nɔnɔmetata 1c). Be woatrɔ CO2 ƒe lolome wòazu CaCO3 ƒe agbɔsɔsɔ la, wowɔ dodokpɔ ƒe ʋuʋudedi to CaCO3 ƒe aŋe dzadzɛ kɔklɔ kple 1 N HCl kple eƒe nɔnɔmetata wɔwɔ ɖe CO2 si trɔ la ŋu me. Wozã SEM nɔnɔmetatawo kple XRD numekuku tsɔ ku CaCO3-mi si ƒo ɖi la ƒe nɔnɔme kple dzadzɛnyenye me. Wozã nusuekpɔmɔ̃ si ƒe lolome nye 1000 tsɔ srɔ̃ nu tso calcium carbonate ƒe wɔwɔme ƒo xlã dɔlékuiawo, calcium carbonate si wowɔ ƒe akpa si wowɔ, kple dɔlékuiawo ƒe dɔwɔwɔ ŋu.
Dejegh-tɔsisia nye nuto nyanyɛ aɖe si me tsi ƒuƒu le ŋutɔ le Iran ƒe Fars Nutome ƒe dzigbeɣetoɖoƒe gome, eye numekulaawo ƒo anyigba si ya ƒo ƒu ƒe kpɔɖeŋuwo nu ƒu tso nutoa me. Woɖe kpɔɖeŋuawo tso anyigba ƒe gowo dzi hena numekukua wɔwɔ. Dzesi dodokpɔ siwo wowɔ le anyigba ƒe kpɔɖeŋuwo dzi ɖee fia be anyigba la nye anyigba si me ke le si womeɖo nyuie o eye wodae ɖe hatsotso si nye SP-SM me le Unified Soil Classification System (USC) nu (Nɔnɔmetata 2a). XRD numekuku ɖee fia be calcite kple quartz koŋue le Dejegh anyigba la me (Nɔnɔmetata 2b). Tsɔ kpe ɖe eŋu la, EDX ƒe numekuku ɖee fia be nu bubuwo abe Al, K, kple Fe ene hã nɔ anyi le agbɔsɔsɔ sue aɖe me.
Be woadzra nudokpɔƒea ƒe togbɛwo ɖo hena ya ƒe ʋuʋu dodokpɔ la, wogbã anyigba la tso eƒe kɔkɔme si nye milimeta 170 to mɔ̃ si ƒe didime nye milimeta 10 me va ɖo anyigba sesẽ aɖe dzi, si wɔe be togbɛ si bɔ si ƒe kɔkɔme nye milimeta 60 eye wòkeke milimeta 210 la do. Le dzɔdzɔme nu la, yamenutomeyimɔ̃woe wɔa ke siwo ƒe kpekpeme le sue wu. Nenema ke kpɔɖeŋu si wodzra ɖo to mɔnu si le etame zazã me la ƒe kpekpeme le sue wu, γ = 14.14 kN/m3, si wɔ ke si wotsɔ da ɖe anyigba si le tsia dzi eye eƒe gbɔɖeme ƒe dzogoe anɔ abe 29.7° ene.
Wotsɔ MICP ƒe tsi nyuitɔ kekeake si wokpɔ le akpa si do ŋgɔ me la ƒu gbe ɖe togbɛa ƒe togbɛ dzi le eƒe dodo ƒe agbɔsɔsɔme si nye 1, 2 kple 3 lm-2 me eye emegbe wodzra kpɔɖeŋuawo ɖo ɖe vidzidɔ me le 30 °C (Fig. 3) hena ŋkeke 9 (si nye ɣeyiɣi nyuitɔ si woatsɔ awɔ dɔe) eye emegbe woɖe wo do goe hena yaƒoƒo ƒe mɔ̃ dodokpɔ.
Le atikewɔwɔ ɖesiaɖe gome la, wodzra lã ene ɖo, ɖeka tsɔ dzidze calcium carbonate ƒe agbɔsɔsɔ kple eƒe anyigba ƒe ŋusẽ to penetrometer zazã me, eye wozã kpɔɖeŋu etɔ̃ susɔeawo tsɔ do tsi ƒe ʋuʋu kpɔ le sesẽme vovovo etɔ̃ me. Le yaƒoƒo ƒe mɔ̃ dodokpɔwo me la, wokpɔ ya ƒe ʋuʋu ƒe agbɔsɔsɔme le ya ƒe duƒuƒu vovovowo me, eye emegbe wotsɔ tsi ƒe ʋuʋu ƒe agbɔsɔsɔme tsɔtsɔ sɔ kple ya ƒe duƒuƒu ƒe nɔnɔmetata de dzesi dzidzenu ƒe gbagbã ƒe sesẽme na atikewɔwɔ ƒe kpɔɖeŋu ɖesiaɖe. Tsɔ kpe ɖe ya ƒe ʋuʋu ƒe dodokpɔwo ŋu la, wotsɔ ke da bɔmb ɖe lã siwo ŋu wowɔ atike ɖo ŋu (si fia be wodo titri kpɔ). Wodzra lã eve bubuwo ɖo hena esia wɔwɔ le wo zazã ƒe agbɔsɔsɔme si nye 2 kple 3 L m−2 me. Ke ƒe bɔmbdada dodokpɔa xɔ miniti 15 kple sisi si nye 120 gm−1, si le asixɔxɔ siwo wotia le numekuku siwo wowɔ va yi me ƒe domedome60,61,62. Adzɔge si le abrasive nozzle kple dune ƒe gɔme dome le tsia dzi nye mm 800, eye wòle milimeta 100 le mɔ̃a ƒe gɔme tame. Woɖo teƒe sia ale be ke siwo le titim la katã kloe ge ɖe togbɛa dzi.
Wowɔ yaƒoƒo ƒe mɔ̃ dodokpɔa le yaƒoƒomɔ̃ si le ʋuʋu ɖi si ƒe didime nye meta 8, kekeme nye meta 0.4 eye eƒe kɔkɔme nye m 1 (Nɔnɔmetata 4a). Wotsɔ gakpo siwo wotsɔ galvanized wɔ yaƒoƒomɔ̃a eye wòte ŋu na ya ƒe duƒuƒu si ade 25 m/s. Tsɔ kpe ɖe eŋu la, wozãa frequency converter tsɔ trɔa asi le fesre ƒe frequency ŋu eye wodzia frequency ɖe edzi vivivi be woakpɔ ya ƒe duƒuƒu si woɖo taɖodzinu na. Nutata 4b fia ke siwo ya ƒo ƒu kple ya ƒe duƒuƒu ƒe nɔnɔme si wodzidze le ya ƒe mɔ̃a me ƒe nɔnɔmetata.
Mlɔeba la, be woatsɔ MICP ƒe atike si menye urealytic o si wodo ɖa le numekuku sia me ƒe emetsonuwo asɔ kple urealytic MICP dziɖuɖu dodokpɔ me tsonu la, wodzra dune ƒe kpɔɖeŋuwo hã ɖo eye wotsɔ nugbagbeviwo ƒe tsi si me urea, calcium chloride kple Sporosarcina pasteurii le da dɔe (elabena ŋutete ɖedzesi aɖe le Sporosarcina pasteurii si be wòawɔ urease63). Dɔlékui ƒe tsi ƒe nukpɔkpɔ ƒe kpekpeme nye 1.5, eye urea kple calcium chloride ƒe agbɔsɔsɔme nye 1 M (wotiae ɖe asixɔxɔ siwo wokafu le numekuku siwo wowɔ va yi me nu36,64,65). Nunyiame ƒe ʋeʋẽ (8 g/L) kple urea (20 g/L) ye nɔa dekɔnu si wotsɔ dea agble me la me. Wowu dɔlékui ƒe tsi la ɖe togbɛa ƒe anyime eye wogblẽe ɖi gaƒoƒo 24 be dɔlékuiwo nalé ɖe eŋu. Le gaƒoƒo 24 ƒe etsɔtsɔ blae megbe la, wotsɔ siminti (calcium chloride kple urea) ƒu gbe ɖe edzi. Woyɔa urealytic MICP dziɖuɖu dodokpɔa le afisia be UMC. Wokpɔ calcium carbonate si le anyigba ƒe kpɔɖeŋu siwo wotsɔ urealytically kple non-urealytically treated me to tsilele me le ɖoɖo si Choi et al.66 do ɖa nu
Nutata 5 fia Bacillus amyloliquefaciens kple Bacillus subtilis ƒe tsitsi ƒe fliwo le dekɔnu me (nunyiame ƒe tsi) si ƒe pH le gɔmedzedzea me nye 5 va ɖo 10. Abe alesi woɖee fia le nɔnɔmetata me ene la, Bacillus amyloliquefaciens kple Bacillus subtilis tsi kabakaba wu le pH 6-8 kple 7-9 me. Eyata woxɔ pH ƒe didime sia le optimization ƒe afɔɖeɖea me.
Tsitsi ƒe fliwo le (a) Bacillus amyloliquefaciens kple (b) Bacillus subtilis le nunyiame ƒe ʋeʋẽ ƒe pH gbãtɔ vovovowo me.
Nutata 6 fia carbon dioxide agbɔsɔsɔme si wowɔ le Bernard limemeter me, si tsi tre ɖi na calcium carbonate (CaCO3) si ƒo ɖi. Esi wònye be woɖo nu ɖeka ɖe ƒuƒoƒo ɖesiaɖe me eye woto vovo tso nu bubuawo ŋu ta la, teƒe ɖesiaɖe si le nɔnɔmetata siawo dzi sɔ kple ya si woyɔna be carbon dioxide ƒe agbɔsɔsɔ si sɔ gbɔ wu le dodokpɔ ma me. Abe alesi woɖee fia le nɔnɔmetata me ene la, esi calcium dzɔtsoƒe ƒe agbɔsɔsɔ dzi ɖe edzi la, calcium carbonate ƒe wɔwɔ dzi ɖe edzi. Eyata alesi calcium dzɔtsoƒea ƒe agbɔsɔsɔme kpɔa ŋusẽ ɖe calcium carbonate ƒe wɔwɔ dzi tẽ. Esi wònye be calcium dzɔtsoƒe kple carbon dzɔtsoƒe sɔ (si nye calcium formate kple calcium acetate) ta la, zi alesi calcium ions dona la, zi nenemae calcium carbonate hã dona (Nɔnɔmetata 6a). Le AS kple AA ƒe atikewo me la, calcium carbonate wɔwɔ yi edzi nɔ dzidzim ɖe edzi esi ɣeyiɣi si wotsɔ daa dɔe dzi ɖe edzi vaseɖe esime tsidzadza ƒe agbɔsɔsɔ metrɔ kloe le ŋkeke 9 megbe o. Le FA ƒe atikewɔwɔ me la, calcium carbonate ƒe wɔwɔme dzi ɖe kpɔtɔ ne ɣeyiɣi si wotsɔ daa dɔe wu ŋkeke 6. Ne wotsɔe sɔ kple atike bubuwo la, atikewɔmɔnu FS ɖee fia be calcium carbonate ƒe wɔwɔme mede tututu o le ŋkeke 3 megbe (Nɔnɔmetata 6b). Le atike FA kple FS me la, wokpɔ calcium carbonate ƒe wɔwɔme bliboa ƒe 70% kple 87% le ŋkeke etɔ̃ megbe, gake le atike AA kple AS me la, agbɔsɔsɔ sia anɔ abe 46% kple 45% ko ene. Esia ɖee fia be atike si wotsɔ formic acid wɔe la ƒe CaCO3 ƒe wɔwɔme sɔ gbɔ wu le gɔmedzedzea me ne wotsɔe sɔ kple atike si wotu ɖe acetate dzi. Gake alesi wowɔa dɔe la dzi ɖena kpɔtɔna ne ɣeyiɣi si wotsɔ daa dɔe le dzidzim ɖe edzi. Woate ŋu aƒo nya ta tso nɔnɔmetata 6c me be le dɔlékuiwo ƒe agbɔsɔsɔ si wu OD1 gɔ̃ hã me la, womewɔa akpa vevi aɖeke le calcium carbonate ƒe wɔwɔ me o.
Tɔtrɔ le CO2 ƒe agbɔsɔsɔ me (kple CaCO3 ƒe agbɔsɔsɔ si sɔ kplii) si Bernard calcimeter dzidze abe (a) calcium dzɔtsoƒe ƒe agbɔsɔsɔme, (b) ɣeyiɣi si woɖo ɖi, (c) OD, (d) pH gbãtɔ, (e) calcium dzɔtsoƒe kple dɔlékui ƒe tsi ƒe sɔsɔme (na atike ɖesiaɖe) ƒe dɔwɔwɔ ene; kple (f) calcium carbonate agbɔsɔsɔme si sɔ gbɔ wu si wowɔ na calcium dzɔtsoƒe kple dɔlékuiwo ƒe ƒuƒoƒo ɖesiaɖe.
Ku ɖe ŋusẽ si pH gbãtɔ si le nusi wotsɔ wɔe me kpɔna ɖe ame dzi ŋu la, nɔnɔmetata 6d ɖee fia be le FA kple FS gome la, CaCO3 ƒe wɔwɔme ɖo agbɔsɔsɔ si sɔ gbɔ wu le pH 7. Nukpɔkpɔ sia sɔ kple numekuku siwo wowɔ va yi be FDH enzymes li ke wu le pH 7-6.7. Ke hã, le AA kple AS gome la, CaCO3 ƒe tsidzadza dzi ɖe edzi ne pH wu 7. Numekuku siwo wowɔ va yi hã ɖee fia be pH ƒe didime nyuitɔ kekeake na CoA enzyme ƒe dɔwɔwɔ tso 8 va ɖo 9.2-6.8. Ne míebu eŋu be pH ƒe didime nyuitɔ kekeake na CoA enzyme ƒe dɔwɔwɔ kple B. amyloliquefaciens ƒe tsitsi nye (8-9.2) kple (6-8), le wo nɔewo yome (Nɔnɔmetata 5a), wole mɔ kpɔm be pH nyuitɔ si le AA ƒe wɔwɔme me anye 8, eye pH ƒe didime eveawo sɔ kple wo nɔewo. Woɖo kpe nyateƒenya sia dzi to dodokpɔwo me, abe alesi woɖee fia le Nɔnɔmetata 6d me ene. Esi wònye be pH nyuitɔ na B. subtilis ƒe tsitsi nye 7-9 (Nɔnɔmetata 5b) eye pH nyuitɔ na CoA enzyme ƒe dɔwɔwɔ nye 8-9.2 ta la, wole mɔ kpɔm be CaCO3 ƒe tsidzadza ƒe dzidziɖedzi si sɔ gbɔ wu anɔ pH ƒe domedome 8-9, si dzi nɔnɔmetata 6d ɖo kpee (si fia be, tsidzadza ƒe pH nyuitɔ nye 9). Nusiwo do tso eme siwo woɖe fia le nɔnɔmetata 6e me ɖee fia be calcium dzɔtsoƒe ƒe tsi kple dɔlékui ƒe tsi ƒe sɔsɔme nyuitɔ nye 1 na acetate kple formate tsi siaa. Be woatsɔe asɔ kple wo nɔewo la, woda atike vovovowo ƒe dɔwɔwɔ (si nye AA, AS, FA, kple FS) ƒe dɔwɔwɔ kpɔ le CaCO3 ƒe wɔwɔme si sɔ gbɔ wu le nɔnɔme vovovowo me (si nye, calcium dzɔtsoƒe ƒe agbɔsɔsɔ, ɣeyiɣi si wotsɔ daa dɔe, OD, calcium dzɔtsoƒe kple dɔlékui ƒe tsi ƒe sɔsɔme, kple pH gbãtɔ). Le atike siwo ŋu wosrɔ̃ nu tsoe dome la, atikewɔmɔnu FS mee CaCO3 ƒe wɔwɔme sɔ gbɔ wu, si ade atikewɔmɔnu AA tɔ ƒe teƒe etɔ̃ (Nɔnɔmetata 6f). Wowɔ dodokpɔ ene siwo me dɔlékui mele o le calcium dzɔtsoƒe eveawo siaa ŋu eye womekpɔ CaCO3 ƒe tsidzadza aɖeke le ŋkeke 30 megbe o.
Nusuekpɔmɔ̃ ƒe nɔnɔmetata siwo woɖe le atikeawo katã me ɖee fia be vaterite ye nye akpa vevitɔ si me wowɔa calcium carbonate le (Nɔnɔmetata 7). Vaterite kristaloawo ƒe nɔnɔme le dzogoe ene me69,70,71. Wokpɔe be calcium carbonate ƒo ɖe dɔlékui ƒe lãmenugbagbeviwo dzi elabena dɔlékui ƒe lãmenugbagbeviwo ƒe anyime xɔ dzo eye ate ŋu awɔ dɔ abe nusi xɔa divalent cations ene. Ne míetsɔ atikewɔmɔnu FS abe kpɔɖeŋu ene le numekuku sia me la, le gaƒoƒo 24 megbe la, calcium carbonate dze egɔme nɔ wɔwɔm ɖe dɔlékui ƒe lãmenugbagbevi aɖewo dzi (Nɔnɔmetata 7a), eye le gaƒoƒo 48 megbe la, dɔlékui ƒe lãmenugbagbevi siwo wotsɔ calcium carbonate tsyɔ la ƒe xexlẽme dzi ɖe edzi ŋutɔ. Tsɔ kpe ɖe eŋu la, abe alesi woɖee fia le Nɔnɔmetata 7b me ene la, woate ŋu ade dzesi vaterite ƒe akpa suewo hã. Mlɔeba le gaƒoƒo 72 megbe la, edze abe vaterite ƒe kristaloawo bla dɔlékui gbogbo aɖewo ene, eye vaterite ƒe akpa suewo ƒe xexlẽme dzi ɖe edzi ŋutɔ (Nɔnɔmetata 7c).
Nusuekpɔmɔ̃ ƒe ŋkuléle ɖe CaCO3 ƒe tsidzadza ŋu le FS ƒe wɔwɔmewo me le ɣeyiɣi aɖe megbe: (a) 24, (b) 48 kple (c) 72 h.
Be woagaku nu me le akpa si tsidzadza ƒe nɔnɔme ŋu la, wowɔ X-ray diffraction (XRD) kple SEM numekukuwo le atikekuiawo ŋu. XRD spectra (Fig. 8a) kple SEM micrographs (Fig. 8b, c) ɖo kpe vaterite kristalo ƒe anyinɔnɔ dzi, elabena woƒe nɔnɔme le abe sabala ene eye wokpɔ ɖekawɔwɔ le vaterite ƒe tawo kple tsidzadza ƒe tawo dome.
(a) CaCO3 kple vaterite si wowɔ ƒe X-ray diffraction spectra tsɔtsɔ sɔ kple wo nɔewo. SEM micrographs of vaterite le (b) 1 kHz kple (c) 5.27 kHz ƒe dzidziɖedzi, le wo nɔewo yome.
Woɖe yaƒoƒo ƒe mɔ̃ dodokpɔwo me tsonu fia le nɔnɔmetata 9a, b. Woateŋu akpɔe tso nɔnɔmetata 9a me be threshold erosion velocity (TDV) si le ke si womewɔ atike na o la anɔ abe 4.32 m/s ene. Le dɔwɔwɔ ƒe agbɔsɔsɔme si nye 1 l/m2 (Nɔnɔmetata 9a) me la, anyigba ƒe bu ƒe agbɔsɔsɔme ƒe fliwo ƒe togbɛwo na akpa sue siwo nye FA, FS, AA kple UMC sɔ kple esiwo le togbɛ si ŋu womewɔ atike ɖo o la tɔ. Esia fia be atikewɔwɔ le atikewɔwɔ ƒe agbɔsɔsɔ sia me mewɔa dɔ o eye ne ya ƒe duƒuƒu wu TDV ko la, anyigba ƒe ƒuƒu tsɛa nu yina eye togbɛwo ƒe ʋuʋu ƒe agbɔsɔsɔme sɔ kple togbɛ si womewɔ atike na o. AS ƒe akpa sue ƒe ʋuʋu ƒe dzidzeme hã bɔbɔ wu akpa bubu siwo ƒe abscissas le anyime (si nye TDV) tɔ (Nɔnɔmetata 9a). Aŋutrɔ siwo le nɔnɔmetata 9b me ɖee fia be le ya ƒe duƒuƒu si sɔ gbɔ wu si nye 25 m/s me la, tsi ƒe ʋuʋu aɖeke medzɔ le togbɛ siwo ŋu wowɔ atike ɖo la me le alesi wozãe ƒe agbɔsɔsɔme si nye 2 kple 3 l/m2 o. Ne míagblɔe bubui la, le FS, FA, AS kple UMC gome la, togbɛawo te ŋu nɔa te ɖe ya ƒe ʋuʋu si CaCO3 ƒe tsɔtsɔ hena vɛ nu wu le wo zazã ƒe agbɔsɔsɔme si nye 2 kple 3 l/m2 wu ya ƒe duƒuƒu si sɔ gbɔ wu (si nye 25 m/s). Eyata TDV ƒe asixɔxɔ si nye 25 m/s si wokpɔ le dodokpɔ siawo me lae nye seɖoƒe si le anyime na dɔwɔwɔ ƒe agbɔsɔsɔme si woɖe fia le nɔnɔmetata 9b me, negbe le AA gome, afisi TDV sɔ kple yaƒoƒo ƒe duƒuƒu si sɔ gbɔ wu kloe.
Ya ƒe ʋuʋu dodokpɔ (a) Kpekpeme dzi ɖeɖe kpɔtɔ tsɔtsɔ sɔ kple ya ƒe duƒuƒu (ezazã ƒe agbɔsɔsɔme 1 l/m2), (b) Dzesi ƒe ʋuʋu ƒe duƒuƒu tsɔtsɔ sɔ kple eŋudɔwɔwɔ ƒe agbɔsɔsɔme kple eƒe wɔwɔme (CA na calcium acetate, CF na calcium formate).
Nutata 10 fia ke siwo wotsɔ atike vovovowo da dɔe ƒe anyigba ƒe ʋuʋu kple alesi wozãe ƒe agbɔsɔsɔme le ke ƒe bɔmbdada dodokpɔa megbe eye woɖe agbɔsɔsɔme me tsonuawo fia le nɔnɔmetata 11. Womeɖe nya si ŋu womewɔ atike ɖo o la fia o elabena meɖe tsitretsitsi aɖeke fia o eye wògbã keŋkeŋ (total mass loss) le ke ƒe bɔmbdada dodokpɔa me. Edze ƒã tso nɔnɔmetata 11 me be kpɔɖeŋu si wotsɔ biocomposition AA da dɔe la bu eƒe kpekpeme ƒe 83.5% le etsɔtsɔ ƒe agbɔsɔsɔme si nye 2 l/m2 me esime kpɔɖeŋu bubuawo katã ɖee fia be ʋuʋudedi si mede 30% o le ke ƒe bɔmbdada ƒe ɖoɖoa me. Esi wodzi atike si woatsɔ awɔ dɔe ɖe edzi va ɖo 3 l/m2 la, kpɔɖeŋu siwo katã ŋu wowɔ atike ɖo la ƒe kpekpeme mede 25% o. Le alesi wozãe ƒe agbɔsɔsɔme eveawo siaa me la, FS si wotsɔ ƒo ƒui ɖee fia be yeate ŋu anɔ te ɖe ke ƒe bɔmbdada nu nyuie wu. Woateŋu agblɔ be bɔmbdada ƒe tsitretsitsi si sɔ gbɔ wu kple esi le sue wu le kpɔɖeŋu siwo ŋu wowɔ atike na le FS kple AA me la tso woƒe CaCO3 ƒe tsidzadza si sɔ gbɔ wu kple esi le sue wu gbɔ (Nɔnɔmetata 6f).
Nusiwo do tso bɔmbdada ɖe ke siwo ƒe nɔnɔme to vovo dzi le sisi ƒe sesẽme si nye 2 kple 3 l/m2 me (aŋutsrɔewo fia ya ƒe mɔfiame, atitsogawo fia ya ƒe mɔfiame si le tsitre ɖe nɔnɔmetata la ƒe yameʋu ŋu).
Abe alesi woɖee fia le nɔnɔmetata 12 me ene la, calcium carbonate si le mɔliawo katã me dzi ɖe edzi esime alesi wozãnɛ ƒe agbɔsɔsɔme dzi ɖe edzi tso 1 L/m2 va ɖo 3 L/m2. Tsɔ kpe ɖe eŋu la, le alesi wozãe katã me la, mɔli si me calcium carbonate sɔ gbɔ ɖo wue nye FS, eye FA kple UMC kplɔe ɖo. Esia fia be ɖewohĩ atike siawo ƒe anyigba ƒe tsitretsitsi ƒe ŋutete lolo wu.
Nutata 13a fia tɔtrɔ si va anyigba ƒe tsitretsitsi le anyigba ƒe kpɔɖeŋu siwo womewɔ atike na o, esiwo dzi wokpɔ ŋusẽ ɖo kple esiwo ŋu wowɔ atike ɖo si wodzidze to permeameter dodokpɔ me. Tso xexlẽme sia me la, edze ƒã be UMC, AS, FA kple FS ƒe atikewo ƒe anyigba ƒe tsitretsitsi dzi ɖe edzi ŋutɔ esime wo zazã ƒe agbɔsɔsɔme dzi ɖe edzi. Gake ŋusẽ si le anyigba ƒe gogloƒe ƒe dzidziɖedzia nɔ sue ŋutɔ le AA ƒe wɔwɔme me. Abe alesi woɖee fia le nɔnɔmetata me ene la, FA kple FS ƒe atike siwo wowɔ le MICP si me urea megblẽ o ƒe yame ƒe gege ɖe eme nyo wu ne wotsɔe sɔ kple MICP si me urea gblẽ. Nutata 13b fia tɔtrɔ si va le TDV me kple anyigba ƒe anyigba ƒe tsitretsitsi. Le xexlẽdzesi sia me la, edze ƒã be le togbɛ siwo ƒe anyigba ƒe tsitretsitsi wu 100 kPa gome la, threshold stripping velocity agbɔ 25 m/s. Esi wònye be woateŋu adzidze anyigba ƒe tsitretsitsi le teƒea bɔbɔe to permeameter dzi ta la, sidzedze sia ateŋu akpeɖeŋu be woabu TDV ne ya ƒe mɔ̃ dodokpɔ aɖeke meli o, si ana wòanye nyonyomedzikpɔkpɔ ƒe dzesi na agblemenukuwo zazã.
SEM ƒe emetsonuwo dze le nɔnɔmetata 14. Nɔnɔmetata 14a-b fia anyigba ƒe kpɔɖeŋu si womewɔ atike na o ƒe akpa sue siwo lolo, si ɖee fia kɔte be ewɔ ɖeka eye dzɔdzɔme kadodo alo siminti aɖeke mele eŋu o. Nutata 14c fia SEM nusuekpɔmɔ̃ si woɖe le kpɔɖeŋu si wotsɔ ɖu wo dzi si wotsɔ MICP si me urea gblẽ da dɔe. Nɔnɔmetata sia ɖe CaCO3 ƒe tsidzadzawo ƒe anyinɔnɔ fia abe calcite polymorphs ene. Abe alesi woɖee fia le Nɔnɔmetata 14d-o me ene la, CaCO3 si ƒo ƒu la blaa nusueawo ɖekae; woate ŋu ade dzesi vaterite kristalo siwo le dzogoe ene me hã le SEM nusuekpɔmɔ̃wo me. Numekuku sia me tsonu kple numekuku siwo wowɔ va yi ɖee fia be CaCO3 ƒe kadodo siwo wowɔ abe vaterite polymorphs ene hã ate ŋu ana mɔ̃ɖaŋununya ƒe ŋusẽ si sɔ; míaƒe emetsonuwo ɖee fia be anyigba ƒe tsitretsitsi dzina ɖe edzi va ɖoa 350 kPa eye dzidzenu ƒe mama ƒe sesẽme dzina ɖe edzi tso 4.32 va ɖo wu 25 m/s. Nusi do tso eme sia sɔ kple numekuku siwo wowɔ va yi me tsonu be MICP-si ƒo CaCO3 ƒe matriki nye vaterite, si ƒe mɔ̃ɖaŋununya ƒe ŋusẽ sɔ eye wòte ŋu nɔa te ɖe ya ƒe ʋuʋu nu13,40 eye ate ŋu alé ya ƒe ʋuʋu ƒe tsitretsitsi si sɔ me ɖe asi le ŋkeke 180 siwo wotsɔ de agble me nutome ƒe nɔnɔmewo me gɔ̃ hã megbe13.
(a, b) Anyigba si womewɔ atike na o ƒe SEM nusuekpɔmɔ̃wo, (c) MICP urea ƒe gbegblẽ dzi ɖuɖu, (df) kpɔɖeŋu siwo wotsɔ AA da dɔe, (gi) kpɔɖeŋu siwo ŋu wowɔ AS ɖo, (jl) kpɔɖeŋu siwo ŋu wowɔ FA ɖo, kple (mo) kpɔɖeŋu siwo ŋu wowɔ FS ɖo le wo zazã ƒe agbɔsɔsɔ si nye 3 L/m2 le dzidziɖedzi vovovowo me.
Nutata 14d-f ɖee fia be le atikewɔwɔ kple AA ƒe atikewo megbe la, calcium carbonate ƒo ɖe anyigba kple kekuawo dome, esime wokpɔ kekui aɖewo siwo womefa o hã. Le AS ƒe akpawo gome la, togbɔ be CaCO3 ƒe agbɔsɔsɔ si wowɔ medzi ɖe edzi boo o (Fig. 6f) hã la, kadodo si le kekui siwo CaCO3 hena vɛ dome ƒe agbɔsɔsɔme dzi ɖe edzi ŋutɔ ne wotsɔe sɔ kple AA ƒe atikewo (Fig. 14g-i).
Tso nɔnɔmetata 14j-l kple 14m-o me la, eme kɔ ƒã be calcium formate zazã abe calcium dzɔtsoƒe ene hea CaCO3 ƒe tsidzadza dzina ɖe edzi ne wotsɔe sɔ kple AS ƒe atike, si sɔ kple calcium mita ƒe dzidzenu siwo le nɔnɔmetata 6f me. Edze abe CaCO3 sia si wotsɔ kpe ɖe eŋu la nɔa kea ƒe akpa aɖewo koŋ dzi ene eye menaa kadodoa ƒe nyonyome nyona ɖe edzi kokoko o. Esia ɖo kpe nuwɔna si wokpɔ va yi dzi: togbɔ be vovototo le CaCO3 ƒe tsidzadza ƒe agbɔsɔsɔ me (Nɔnɔmetata 6f) hã la, atike etɔ̃awo (AS, FA kple FS) meto vovo boo le anti-eolian (ya) ƒe dɔwɔwɔ (Nɔnɔmetata 11) kple anyigba ƒe tsitretsitsi gome o (Nɔnɔmetata 13a).
Be woate ŋu akpɔ dɔlékui ƒe lãmenugbagbevi siwo ŋu CaCO3 le kple dɔlékui ƒe dzesi le kristalo siwo ƒo ɖi dzi nyuie wu la, woɖe SEM nusuekpɔmɔ̃ siwo lolo ŋutɔ eye woɖe emetsonuwo fia le nɔnɔmetata 15. Abe alesi woɖee fia ene la, calcium carbonate ƒua du ɖe dɔlékui ƒe lãmenugbagbeviwo dzi eye wònaa nuclei siwo hiã na tsidzadza le afima. Nɔnɔmetata la ɖe kadodo siwo le dɔ wɔm kple esiwo mele dɔ wɔm o siwo CaCO3 hena vɛ hã fia. Woate ŋu aƒo nya ta be kadodo siwo mewɔa dɔ o ƒe dzidziɖedzi ɖesiaɖe mehea mɔ̃ɖaŋununya ƒe nuwɔna ƒe ŋgɔyiyi geɖe vɛ kokoko o. Eyata CaCO3 ƒe tsidzadza ƒe dzidziɖedzi mehea mɔ̃ɖaŋununya ƒe ŋusẽ si lolo wu vɛ kokoko o eye tsidzadza ƒe ɖoɖo hã wɔa akpa vevi aɖe. Wosrɔ̃ nu tso nya sia hã ŋu le Terzis kple Laloui72 kple Soghi kple Al-Kabani ƒe agbalẽwo me45,73. Be woagaku ƒomedodo si le tsidzadza ƒe nɔnɔme kple mɔ̃ɖaŋununya ƒe ŋusẽ dome me la, wokafu MICP numekuku siwo zãa μCT nɔnɔmetatawo, si gbɔ numekuku sia ƒe ŋutete ŋu (si fia be woato calcium dzɔtsoƒe kple dɔlékuiwo ƒe ƒuƒoƒo vovovowo vɛ na MICP si me amonia mele o).
CaCO3 na kadodo siwo le dɔ wɔm kple esiwo mewɔa dɔ o va le kpɔɖeŋu siwo wotsɔ (a) AS ƒe wɔwɔme kple (b) FS ƒe wɔwɔme da dɔe me eye wògblẽ dɔlékui ƒe lãmenugbagbeviwo ƒe dzesi ɖe tsiƒuƒua dzi.
Abe alesi woɖee fia le nɔnɔmetata 14j-o kple 15b me ene la, CaCO film aɖe li (le EDX ƒe numekuku nu la, nu ɖesiaɖe si le film la me ƒe alafa memamã ƒe wɔwɔme nye carbon 11%, oxygen 46.62% kple calcium 42.39%, si te ɖe CaCO ƒe alafa memamã si le nɔnɔmetata 16 me ŋu ŋutɔ). Film sia tsyɔa vaterite ƒe kristalo kple anyigba ƒe akpa suewo dzi, si kpena ɖe ame ŋu be anyigba kple anyigba ƒe ƒuƒoƒoa ƒe blibonyenye nanɔ anyi. Wokpɔ film sia ƒe anyinɔnɔ le kpɔɖeŋu siwo wotsɔ atike si wotsɔ formate wɔe la me ko.
Tabla 2 tsɔ anyigba siwo dzi wotsɔ MICP mɔ siwo gblẽa nu le urea nu kple esiwo megblẽa nu le urea o ŋu dɔ na le numekuku siwo wowɔ va yi kple numekuku sia me la sɔ kple anyigba ƒe ŋusẽ, dzidzenu ƒe ʋuʋu ƒe sesẽme, kple CaCO3 si tso nugbagbewo gbɔ. Numekuku siwo wowɔ tso ya ƒe ʋuʋu ƒe tsitretsitsi ŋu le togbɛ siwo wotsɔ MICP da dɔe ƒe kpɔɖeŋuwo ŋu la mesɔ gbɔ o. Meng kple exɔlɔ̃wo. ku nu me le ya ƒe ʋuʋu ƒe tsitretsitsi ŋu le togbɛ siwo gblẽa nu le urea ŋu siwo ŋu MICP da dɔ le ƒe kpɔɖeŋuwo zazã me to aŋgba ƒe yaƒoƒomɔ̃ zazã me,13 gake le numekuku sia me la, wodo togbɛ siwo me urea gblẽna o ƒe kpɔɖeŋuwo (kple esiwo gblẽa nu le urea ŋu) kpɔ le yaƒoƒomɔ̃ me eye wotsɔ dɔlékui kple nu vovovo ene siwo wotsɔ ƒo ƒui da dɔ na wo.
Abe alesi woate ŋu akpɔe ene la, numekuku aɖewo siwo wowɔ va yi bu alesi wozãnɛ ƒe agbɔsɔsɔ gã si wu 4 L/m213,41,74 ŋu. Enyo be míade dzesii be ate ŋu anye be womate ŋu azã tsizazã ƒe agbɔsɔsɔ gãwo bɔbɔe le agblea me le ganyawo gome o le gazazã siwo do ƒome kple tsi nana, ʋuɖoɖo kple tsi gbogbo aɖewo zazã ta. Dɔwɔwɔ ƒe agbɔsɔsɔme si bɔbɔ ɖe anyi abe 1.62-2 L/m2 hã kpɔ anyigba ƒe ŋusẽ nyui aɖe si ade 190 kPa kple TDV si wu 25 m/s. Le numekuku si míele wɔwɔm fifia me la, togbɛ siwo wotsɔ MICP si wotu ɖe formate dzi da dɔe si me urea ƒe gbegblẽ mele o la ɖo anyigba ƒe ŋusẽ gã si sɔ kple esiwo wokpɔ kple urea ƒe gbegblẽ ƒe mɔnu le dɔwɔwɔ ƒe agbɔsɔsɔme ɖeka ma ke me (si fia be, kpɔɖeŋu siwo wotsɔ MICP si wotu ɖe formate dzi da dɔe si me urea ƒe gbegblẽ mele o hã te ŋu ɖo anyigba ƒe ŋusẽ ƒe asixɔxɔ ƒe didime ma ke gbɔ abe alesi Meng et al., 13, Figure 13a) ka nya tae le dɔbiagbalẽvi ƒe agbɔsɔsɔ si lolo wu. Woateŋu akpɔe hã be le 2 L/m2 zazã ƒe agbɔsɔsɔ me la, calcium carbonate ƒe kutsetse hena ya ƒe ʋuʋu dzi ɖeɖe kpɔtɔ le ya ƒe duƒuƒu si nye 25 m/s me nye 2.25% na formate-based MICP si me urea ƒe gbegblẽ mele o, si te ɖe CaCO3 ƒe agbɔsɔsɔ si hiã ŋu ŋutɔ (si nye 2.41%) ne wotsɔe sɔ kple togbɛ siwo wotsɔ control MICP da dɔ kple urea ƒe gbegblẽ le dɔwɔwɔ ma ke me ya ƒe duƒuƒu kple ya ƒe duƒuƒu ma ke (25 m/s).
Eyata woateŋu aƒo nya ta tso kplɔ̃ sia dzi be urea ƒe gbegblẽ ƒe mɔnu kple urea ƒe gbegblẽ ƒe mɔnu siaa ateŋu ana dɔwɔwɔ si dzi woda asi ɖo ŋutɔ le anyigba ƒe tsitretsitsi kple TDV gome. Vovototo vevitɔe nye be amoniaka mele nugbegblẽmɔ si me urea mele o la me o eyata mekpɔa ŋusẽ ɖe nutome dzi boo o. Tsɔ kpe ɖe eŋu la, edze abe MICP mɔnu si wotu ɖe formate dzi si me urea ƒe gbegblẽ mele o si wodo ɖa le numekuku sia me la wɔa dɔ nyuie wu MICP mɔnu si wotu ɖe acetate dzi si me urea ƒe gbegblẽ mele o ene. Togbɔ be Mohebbi kple exɔlɔ̃wo gblɔ be: srɔ̃ nu tso MICP mɔnu si wotu ɖe acetate dzi ŋu urea ƒe gbegblẽ manɔmee, woƒe numekukua lɔ kpɔɖeŋu siwo le anyigba gbadzawo dzi ɖe eme9. Le tsidzadza ƒe agbɔsɔsɔ si lolo wu si tso ʋuʋudedi ƒe wɔwɔme ƒo xlã togbɛwo ƒe kpɔɖeŋuwo kple ʋuʋudedi si dona tso eme, si wɔnɛ be TDV ɖiɖina ta la, wole mɔ kpɔm be ya ƒe ʋuʋu le togbɛwo ƒe kpɔɖeŋuwo me adze ƒã wu esi le anyigba gbadzawo dzi le duƒuƒu ma ke me.