CN117550866A - Phosphogypsum-based lightweight aggregate embedded with microorganisms and preparation method and application thereof - Google Patents
Phosphogypsum-based lightweight aggregate embedded with microorganisms and preparation method and application thereof Download PDFInfo
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- CN117550866A CN117550866A CN202311258295.8A CN202311258295A CN117550866A CN 117550866 A CN117550866 A CN 117550866A CN 202311258295 A CN202311258295 A CN 202311258295A CN 117550866 A CN117550866 A CN 117550866A
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- China
- Prior art keywords
- phosphogypsum
- lightweight aggregate
- based lightweight
- aggregate
- bacillus
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Links
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 title claims abstract description 179
- 244000005700 microbiome Species 0.000 title claims abstract description 53
- 238000002360 preparation method Methods 0.000 title claims abstract description 36
- 239000000843 powder Substances 0.000 claims abstract description 82
- 239000002893 slag Substances 0.000 claims abstract description 56
- 239000004570 mortar (masonry) Substances 0.000 claims abstract description 34
- 239000003513 alkali Substances 0.000 claims abstract description 33
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 33
- 239000004567 concrete Substances 0.000 claims abstract description 29
- 239000000203 mixture Substances 0.000 claims abstract description 27
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 20
- 239000010959 steel Substances 0.000 claims abstract description 20
- 238000005507 spraying Methods 0.000 claims abstract description 13
- 238000002156 mixing Methods 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims abstract description 9
- 230000001580 bacterial effect Effects 0.000 claims description 57
- 241000894006 Bacteria Species 0.000 claims description 49
- 239000007788 liquid Substances 0.000 claims description 49
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 47
- 238000000034 method Methods 0.000 claims description 34
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 30
- 239000000243 solution Substances 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 230000033558 biomineral tissue development Effects 0.000 claims description 24
- 239000000499 gel Substances 0.000 claims description 23
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 19
- 239000004202 carbamide Substances 0.000 claims description 19
- 239000002131 composite material Substances 0.000 claims description 15
- 238000002791 soaking Methods 0.000 claims description 14
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 13
- 239000004115 Sodium Silicate Substances 0.000 claims description 11
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 11
- 230000001954 sterilising effect Effects 0.000 claims description 11
- 241000193830 Bacillus <bacterium> Species 0.000 claims description 10
- 239000000725 suspension Substances 0.000 claims description 10
- 239000002504 physiological saline solution Substances 0.000 claims description 6
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 5
- 241000194107 Bacillus megaterium Species 0.000 claims description 5
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 159000000007 calcium salts Chemical class 0.000 claims description 5
- 230000000813 microbial effect Effects 0.000 claims description 5
- 235000010413 sodium alginate Nutrition 0.000 claims description 5
- 239000000661 sodium alginate Substances 0.000 claims description 5
- 229940005550 sodium alginate Drugs 0.000 claims description 5
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 5
- 235000011152 sodium sulphate Nutrition 0.000 claims description 5
- 241001328127 Bacillus pseudofirmus Species 0.000 claims description 4
- 108010010803 Gelatin Proteins 0.000 claims description 4
- 235000010643 Leucaena leucocephala Nutrition 0.000 claims description 4
- 239000012190 activator Substances 0.000 claims description 4
- VSGNNIFQASZAOI-UHFFFAOYSA-L calcium acetate Chemical compound [Ca+2].CC([O-])=O.CC([O-])=O VSGNNIFQASZAOI-UHFFFAOYSA-L 0.000 claims description 4
- 239000001639 calcium acetate Substances 0.000 claims description 4
- 229960005147 calcium acetate Drugs 0.000 claims description 4
- 235000011092 calcium acetate Nutrition 0.000 claims description 4
- MKJXYGKVIBWPFZ-UHFFFAOYSA-L calcium lactate Chemical compound [Ca+2].CC(O)C([O-])=O.CC(O)C([O-])=O MKJXYGKVIBWPFZ-UHFFFAOYSA-L 0.000 claims description 4
- 239000001527 calcium lactate Substances 0.000 claims description 4
- 229960002401 calcium lactate Drugs 0.000 claims description 4
- 235000011086 calcium lactate Nutrition 0.000 claims description 4
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 4
- 238000012258 culturing Methods 0.000 claims description 4
- 239000008273 gelatin Substances 0.000 claims description 4
- 229920000159 gelatin Polymers 0.000 claims description 4
- 235000019322 gelatine Nutrition 0.000 claims description 4
- 235000011852 gelatine desserts Nutrition 0.000 claims description 4
- 238000004659 sterilization and disinfection Methods 0.000 claims description 4
- 241000193752 Bacillus circulans Species 0.000 claims description 3
- 241000194108 Bacillus licheniformis Species 0.000 claims description 3
- 244000063299 Bacillus subtilis Species 0.000 claims description 3
- 235000014469 Bacillus subtilis Nutrition 0.000 claims description 3
- 241000193388 Bacillus thuringiensis Species 0.000 claims description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical group [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 3
- KDXKERNSBIXSRK-UHFFFAOYSA-N Lysine Natural products NCCCCC(N)C(O)=O KDXKERNSBIXSRK-UHFFFAOYSA-N 0.000 claims description 3
- 239000004472 Lysine Substances 0.000 claims description 3
- 241000193386 Lysinibacillus sphaericus Species 0.000 claims description 3
- 241000881860 Paenibacillus mucilaginosus Species 0.000 claims description 3
- 239000007633 bacillus mucilaginosus Substances 0.000 claims description 3
- 229940097012 bacillus thuringiensis Drugs 0.000 claims description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 3
- 239000000920 calcium hydroxide Substances 0.000 claims description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 3
- 229920001285 xanthan gum Polymers 0.000 claims description 3
- 241000193375 Bacillus alcalophilus Species 0.000 claims description 2
- 239000001110 calcium chloride Substances 0.000 claims description 2
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 2
- 235000010418 carrageenan Nutrition 0.000 claims description 2
- 239000000679 carrageenan Substances 0.000 claims description 2
- 229920001525 carrageenan Polymers 0.000 claims description 2
- 229940113118 carrageenan Drugs 0.000 claims description 2
- 235000019353 potassium silicate Nutrition 0.000 claims description 2
- 239000012266 salt solution Substances 0.000 claims description 2
- 235000019794 sodium silicate Nutrition 0.000 claims description 2
- 239000000230 xanthan gum Substances 0.000 claims description 2
- 235000010493 xanthan gum Nutrition 0.000 claims description 2
- 229940082509 xanthan gum Drugs 0.000 claims description 2
- UHVMMEOXYDMDKI-JKYCWFKZSA-L zinc;1-(5-cyanopyridin-2-yl)-3-[(1s,2s)-2-(6-fluoro-2-hydroxy-3-propanoylphenyl)cyclopropyl]urea;diacetate Chemical compound [Zn+2].CC([O-])=O.CC([O-])=O.CCC(=O)C1=CC=C(F)C([C@H]2[C@H](C2)NC(=O)NC=2N=CC(=CC=2)C#N)=C1O UHVMMEOXYDMDKI-JKYCWFKZSA-L 0.000 claims description 2
- 235000021508 Coleus Nutrition 0.000 claims 1
- 244000061182 Coleus blumei Species 0.000 claims 1
- 240000007472 Leucaena leucocephala Species 0.000 claims 1
- 239000000834 fixative Substances 0.000 claims 1
- 229940014259 gelatin Drugs 0.000 claims 1
- 229940032158 sodium silicate Drugs 0.000 claims 1
- 239000004566 building material Substances 0.000 abstract description 4
- 230000000694 effects Effects 0.000 description 23
- 238000012360 testing method Methods 0.000 description 20
- 210000004027 cell Anatomy 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 239000004568 cement Substances 0.000 description 10
- 238000001035 drying Methods 0.000 description 10
- 238000010521 absorption reaction Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 239000011148 porous material Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 239000011575 calcium Substances 0.000 description 8
- 108010046334 Urease Proteins 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 6
- 229910001424 calcium ion Inorganic materials 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 6
- 239000001963 growth medium Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 5
- 241000193755 Bacillus cereus Species 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000010790 dilution Methods 0.000 description 4
- 239000012895 dilution Substances 0.000 description 4
- 230000035876 healing Effects 0.000 description 4
- 230000008439 repair process Effects 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 241000220479 Acacia Species 0.000 description 3
- 229940041514 candida albicans extract Drugs 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 238000005538 encapsulation Methods 0.000 description 3
- 239000010881 fly ash Substances 0.000 description 3
- 230000003100 immobilizing effect Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- 239000012138 yeast extract Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000003139 buffering effect Effects 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 238000003776 cleavage reaction Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 239000002609 medium Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 230000007017 scission Effects 0.000 description 2
- 239000000741 silica gel Substances 0.000 description 2
- 229910002027 silica gel Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- GJCOSYZMQJWQCA-UHFFFAOYSA-N 9H-xanthene Chemical compound C1=CC=C2CC3=CC=CC=C3OC2=C1 GJCOSYZMQJWQCA-UHFFFAOYSA-N 0.000 description 1
- 229910021532 Calcite Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 210000004666 bacterial spore Anatomy 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000006285 cell suspension Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013068 control sample Substances 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 229910001653 ettringite Inorganic materials 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000000855 fermentation Methods 0.000 description 1
- 230000004151 fermentation Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 230000009442 healing mechanism Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000009630 liquid culture Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000002906 microbiologic effect Effects 0.000 description 1
- 230000001089 mineralizing effect Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000002135 nanosheet Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000010451 perlite Substances 0.000 description 1
- 235000019362 perlite Nutrition 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000002686 phosphate fertilizer Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000003516 soil conditioner Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 229920000247 superabsorbent polymer Polymers 0.000 description 1
- 239000004583 superabsorbent polymers (SAPs) Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000035899 viability Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/142—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing synthetic or waste calcium sulfate cements
- C04B28/143—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing synthetic or waste calcium sulfate cements the synthetic calcium sulfate being phosphogypsum
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/08—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding porous substances
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/60—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only artificial stone
- C04B41/61—Coating or impregnation
- C04B41/70—Coating or impregnation for obtaining at least two superposed coatings having different compositions
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention relates to the technical field of building material preparation, and discloses a phosphogypsum-based lightweight aggregate embedded with microorganisms, and a preparation method and application thereof, wherein the preparation method of the phosphogypsum-based lightweight aggregate comprises the following steps: (1) Mixing phosphogypsum powder, slag powder and steel slag powder to obtain a mixture; (2) Placing the mixture into a granulating device, spraying an alkali-exciting agent, and stirring to obtain primary alkali-exciting aggregate; (3) Natural curing and constant temperature and humidity standard curing are carried out on the primary alkali-activated aggregate, so that the natural curing agent is obtained; the mass ratio of phosphogypsum powder to slag powder to steel slag powder is 60-70:30-40:0-10. The phosphogypsum-based lightweight aggregate prepared by the invention not only can be used as aggregate in mortar and concrete, but also can be applied to self-repairing of cracks in mortar and concrete, and has wider applicable types.
Description
Technical Field
The invention relates to the technical field of building material preparation, in particular to phosphogypsum-based lightweight aggregate embedded with microorganisms, and a preparation method and application thereof.
Background
Phosphogypsum is an industrial solid waste generated in the wet-process phosphoric acid production process. Meanwhile, with the rapid development of the phosphate fertilizer industry, the phosphogypsum emission is increased sharply. Phosphogypsum landfill can release fluorine, phosphorus, organic matters, heavy metals, radioactive elements and other harmful impurities, and seriously harm the environment. In view of the abundance of phosphogypsum, recycling phosphogypsum as a building material is a good direction. CaSO in phosphogypsum 4 ·2H 2 The O content is generally above 85%, and can be used as a source of calcium sulfate. Existing studies have demonstrated that phosphogypsum can be used as a cement retarder, such as soil conditioner, building gypsum and road filler, but the comprehensive utilization rate of phosphogypsum is still lower than 40%. Cement and concrete are the building materials currently in greatest demand, and the use of phosphogypsum as a raw material for cement and concrete is considered as an effective way to treat such solid waste. In order to reduce the use of natural resources such as clay, shale and the like, and the solid waste is used as a raw material for recycling. In the recycling strategy, the preparation of the lightweight concrete and mortar aggregate has great practical application potential, especially in the case that the shortage of natural raw materials such as sand, gravel, broken stone and the like is expected to occur.
The concrete structure inevitably generates cracks due to deformation, creep, fatigue, dry shrinkage, freeze thawing cycles and the like, and the cracks not only reduce the strength of the concrete structure, but also provide channels for corrosive substances in the environment to permeate into the concrete. Early shrinkage cracking can be alleviated by quality control of the feedstock and adjustment of the mixing ingredients, such as addition of limestone fines, use of expanding agents, use of superabsorbent polymers, optimization of particle size distribution, addition of fibers, etc. However, the cracking resistance effect of these precautions may not be sufficient to cope with the actual environment in which the concrete is used, especially with post-cracking in extreme climates and mechanical environments. Once a fracture occurs, the surface fracture can be repaired manually, but internal and inaccessible fractures are often difficult to manage. In addition, conventional repair techniques, such as sealing, grouting, and coating, are often unsuitable, expensive, time consuming, and sometimes prone to failure. Self-healing is therefore an attractive concept for infrastructure, as it allows cracks to heal without any external intervention, and is currently of great interest in many field applications and trials. Accordingly, crack repair in concrete structures has been the subject of research in the field of concrete and mortar materials, and among many methods for repairing concrete or mortar cracks, the use of bacteria to repair concrete cracks has received much attention.
In order to maintain the activity of bacteria in concrete or mortar, it is necessary to protect the bacteria or bacterial spores by encapsulation or fixation with a carrier before the concrete or mortar cracks. The immobilized microorganism technology can combine free microorganism with a specific carrier by a physical or chemical method to fix the free microorganism in a certain space area so as to improve the concentration of microorganism cells and buffer the poison of external substances to the cells, thereby achieving the purpose of reinforcing the self-repairing of concrete and mortar. The immobilization has a plurality of carriers and methods, and the immobilization of different carrier types and combination modes has great difference on self-repairing of concrete and mortar. For example, bacteria are wrapped in materials such as ceramsite, diatomite, polyurethane, ceramic particles, silica gel, graphite nano-sheets, clay particles, expanded perlite, cellulose fibers and the like, but the embedding efficiency is low, the strain leakage rate is high, so that the activity of the strain is low, and the self-repairing capability of concrete and mortar is affected.
Therefore, how to adjust and optimize the preparation method of phosphogypsum-based lightweight aggregate for embedding microorganisms, improve the embedding efficiency of the strain, ensure the activity of the strain and improve the self-repairing capability of the strain to concrete and mortar is a technical problem to be solved in the field.
Disclosure of Invention
In view of the above, the invention provides phosphogypsum-based lightweight aggregate with good particle shape, high compressive strength of the cylinder, moderate porosity and higher water absorption.
Further, the invention provides a preparation method of the phosphogypsum-based lightweight aggregate embedded with the microorganism.
Further, the invention provides application of the phosphogypsum-based lightweight aggregate embedded with the microorganism in concrete or mortar materials.
In a first aspect, the invention provides a method for preparing phosphogypsum-based lightweight aggregate, comprising the following steps:
(1) Mixing phosphogypsum powder, slag powder and steel slag powder to obtain a mixture;
(2) Placing the mixture into a granulating device, spraying an alkali-exciting agent, and stirring to obtain primary alkali-exciting aggregate;
(3) Natural curing and constant temperature and humidity standard curing are carried out on the primary alkali-activated aggregate, so that the natural curing agent is obtained;
the mass ratio of phosphogypsum powder to slag powder to steel slag powder is 60-70:30-40:0-10.
In an alternative embodiment, the mass ratio of the mixture to the alkali-activator is 1:0.25-0.51.
In an alternative embodiment, the alkali-activator is at least one of the following solutions:
the calcium hydroxide suspension is prepared from the following components: the mass ratio of water is 1:5-6 configuration;
Sodium silicate with modulus of 2.5-3.1;
the mass ratio of the sodium silicate to the sodium hydroxide solution is 0.3-1.5:1, wherein before mixing, the sodium silicate has a water glass modulus of 0.947-3.23 and a sodium hydroxide concentration of 4-6 mol/L;
the molar ratio of the sodium sulfate solution to the sodium hydroxide solution is 1:4-6, wherein before mixing, the concentration of the sodium sulfate solution is 0.8mol/L-1mol/L, and the concentration of the sodium hydroxide solution is 4mol/L-6mol/L.
In an alternative embodiment, in step (2), the stirring includes stirring at 55r/min to 75r/min for 15min to 20min.
In an alternative embodiment, in the step (3), the natural curing temperature is 20 ℃ to 30 ℃, the relative humidity is 35% to 65%, and the curing time is 1d to 2d.
In an alternative embodiment, in the step (3), the temperature of the constant temperature and humidity standard curing is 19-21 ℃, the relative humidity is 85-95%, and the curing time is 2d-3d.
In a second aspect, the invention provides phosphogypsum-based lightweight aggregate prepared by the preparation method.
In a third aspect, the present invention provides a method for preparing phosphogypsum-based lightweight aggregate embedded with microorganisms, comprising the steps of: pretreating the phosphogypsum-based lightweight aggregate; and respectively soaking the pretreated phosphogypsum-based lightweight aggregate in cementing liquid and a composite bacterial fixing agent to obtain the phosphogypsum-based lightweight aggregate.
In an alternative embodiment, the preprocessing step includes: sterilizing the phosphogypsum-based lightweight aggregate, wherein the sterilization temperature is 120-121 ℃ and the sterilization time is 20-40 min.
In an alternative embodiment, the cement contains 17g/L to 23g/L urea and 0.1mol/L to 0.5mol/L calcium salt solution.
In an alternative embodiment, the calcium salt is at least one of calcium acetate, calcium nitrate, calcium chloride, calcium lactate.
In an alternative embodiment, the ratio of the mass of the pre-treated phosphogypsum-based lightweight aggregate to the volume of the cementitious liquid is 0.6-0.74:1, the ratio is g/mL.
In an alternative embodiment, the soaking time in the cement is 8h to 12h.
In an alternative embodiment, the composite bacterial immobilizing agent comprises a gel aqueous solution and a carbonate mineralization bacterial liquid.
In an alternative embodiment, the gel is at least one of sodium alginate, acacia, xanthan, gelatin, carrageenan, sodium silicate.
In an alternative embodiment, the mass fraction of gel in the aqueous gel solution is 3wt% to 5wt%.
In an alternative embodiment, the carbonate mineralizer is at least one of bacillus subtilis, bacillus alkalophilus, bacillus sphaericus, bacillus curvatus, bacillus cereus, bacillus pseudofirmus, bacillus thuringiensis, bacillus licheniformis, bacillus mucilaginosus, bacillus circulans, bacillus megaterium, and bacillus boro-resistant lysine.
In an alternative embodiment, the concentration of the carbonate mineralization bacterial liquid is 10 8 CFU/mL-l0 9 CFU/mL。
In an alternative embodiment, the volume ratio of the gel aqueous solution to the carbonate mineralization bacterial solution is 1:1-2.
In an alternative embodiment, the ratio of the mass of the pre-treated phosphogypsum-based lightweight aggregate to the volume of the composite immobilized microbial agent is 0.6-0.8:1, the ratio is g/mL.
In an alternative embodiment, the soaking in the composite immobilized microbial agent comprises: soaking at 23-28deg.C and 0.7-1.5 bar for 12-24 hr.
In an alternative embodiment, the preparation method of the carbonate mineralization bacterial liquid comprises the following steps: selecting carbonate mineralized bacteria single colony, and culturing at 26-29 deg.c and 170-220 rpm for 48-72 hr to obtain original bacteria liquid; centrifuging the original bacterial liquid, placing the bacterial liquid in sterile physiological saline for resuspension to obtain carbonate mineralized bacterial liquid, and preserving the carbonate mineralized bacterial liquid at the temperature of 4 ℃ for later use.
In a fourth aspect, the invention provides the phosphogypsum-based lightweight aggregate with embedded microorganisms prepared by the method.
In a fifth aspect, the invention provides an application of the phosphogypsum-based lightweight aggregate embedded with microorganisms in self-repairing mortar or concrete.
The invention mixes the dry materials, then puts into the balling disc to add alkali excitant, the balling mechanism of this craft is, alkali excitant adds and makes the material wet in the course of balling disc rotation, along with the rotation of balling disc, collide between material and baffle, roll balling, adopt 55r/min-75r/min rotational speed, make wet material adhere each other, roll and form the spheroid of 2mm-3mm diameter.
The natural curing aims to harden the internal water of the lightweight aggregate and ensure that the internal structure of the lightweight aggregate has certain stability. The standard curing under constant temperature and humidity is accelerated hardening, and the strength of the lightweight aggregate is further improved.
Compared with the prior art, the technical scheme of the invention has the following advantages:
1. the preparation method of phosphogypsum-based lightweight aggregate provided by the invention comprises the following steps: mixing phosphogypsum powder, slag powder and steel slag powder, then placing into a granulating device, spraying an alkali exciting agent, and stirring to obtain primary alkali exciting aggregate; natural curing and constant temperature and humidity standard curing are carried out on the primary alkali-activated aggregate, and the phosphogypsum powder, slag powder and steel slag powder are obtained, wherein the mass ratio of the phosphogypsum powder to the slag powder is 60-70:30-40:0-10. The phosphogypsum-based lightweight aggregate prepared by the preparation method has good particle size, high compressive strength of a cylinder, moderate porosity and higher water absorption; meanwhile, the porous material has moderate porosity, higher water absorption and strong adsorption capacity, is favorable for forming a stable reticular structure, and provides conditions for the subsequent adsorption of the embedded carbonate mineralized bacteria. Meanwhile, the preparation method is simple in process, economical and easy to industrialize. The phosphogypsum-based lightweight aggregate not only can be used as aggregate in mortar and concrete, but also can be applied to the self-repairing effect of cracks in the mortar and the concrete, and has wider applicable types.
2. The invention provides a preparation method of phosphogypsum-based lightweight aggregate embedded with microorganisms, which comprises the steps of immersing phosphogypsum-based lightweight aggregate in cementing liquid to enable pores and surfaces of the lightweight aggregate to adsorb a large amount of calcium ions and urea; the composite bacterial fixing agent is soaked, so that gel in the composite bacterial fixing agent reacts with calcium ions adsorbed on the lightweight aggregate rapidly and wraps the periphery of phosphogypsum-based lightweight aggregate to achieve a better crosslinking effect, and meanwhile, carbonate mineralization bacteria are wrapped in the gel and fixed in the interior and the surface of the phosphogypsum-based lightweight aggregate, so that the encapsulation efficiency of the carbonate mineralization bacteria is effectively improved, the activity of the bacteria is ensured, a relatively stable living environment is provided for the carbonate mineralization bacteria, the temperature adaptation range of the bacterial strain is improved, the buffering capacity of the bacterial strain on acid-base change is also enhanced, and the self-repairing efficiency of the bacterial strain is effectively improved.
3. According to the preparation method of the phosphogypsum-based lightweight aggregate for embedding the microorganisms, provided by the invention, the ratio of the mass of the pretreated phosphogypsum-based lightweight aggregate to the volume of the cementing liquid is controlled, and the ratio of the mass of the pretreated phosphogypsum-based lightweight aggregate to the volume of the composite microbial fixing agent is controlled, so that secondary pollution is avoided in the process of gel embedding the microorganisms.
4. According to the preparation method of the phosphogypsum-based lightweight aggregate for embedding the microorganisms, provided by the invention, the soaking time in the cementing liquid is 8-12 hours, so that calcium salt and gel can be better crosslinked, incomplete crosslinking is avoided, and the mechanical strength of the phosphogypsum-based lightweight aggregate for embedding the microorganisms and the activity of carbonate mineralization bacteria are prevented from being reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flowchart of a method for preparing phosphogypsum-based lightweight aggregate embedding microorganisms according to an embodiment of the present invention.
FIG. 2 is a flow chart of strain activity testing and leakage of the microorganism-embedded phosphogypsum-based lightweight aggregate of the present invention.
FIG. 3 is a schematic illustration of a cleavage process of the present invention for producing a cleavage.
FIG. 4 is a schematic diagram showing the crack healing condition of the mortar of the experimental example of the invention.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
In one aspect, the preparation method of phosphogypsum-based lightweight aggregate provided by the invention comprises the following steps: mixing phosphogypsum powder, slag powder and steel slag powder, then placing into a granulating device, spraying an alkali exciting agent, and stirring to obtain primary alkali exciting aggregate; natural curing and constant temperature and humidity standard curing are carried out on the primary alkali-activated aggregate, and the phosphogypsum powder, slag powder and steel slag powder are obtained, wherein the mass ratio of the phosphogypsum powder to the slag powder is 60-70:30-40:0-10. The phosphogypsum-based lightweight aggregate prepared by the preparation method has good particle size, high compressive strength of a cylinder, moderate porosity and higher water absorption; meanwhile, the porous material has moderate porosity, higher water absorption and strong adsorption capacity, is favorable for forming a stable reticular structure, and provides conditions for the subsequent adsorption of the embedded carbonate mineralized bacteria. Meanwhile, the preparation method is simple in process, economical and easy to industrialize. The phosphogypsum-based lightweight aggregate not only can be used as aggregate in mortar and concrete, but also can be applied to the self-repairing effect of cracks in the mortar and the concrete, and has wider applicable types.
On the other hand, the preparation method of the phosphogypsum-based lightweight aggregate embedded with the microorganism provided by the invention comprises the steps of immersing the phosphogypsum-based lightweight aggregate in cementing liquid, so that a large amount of calcium ions and urea are adsorbed on the pores and the surface of the lightweight aggregate; the composite bacterial fixing agent is soaked, so that gel in the composite bacterial fixing agent reacts with calcium ions adsorbed on the lightweight aggregate rapidly and wraps the periphery of phosphogypsum-based lightweight aggregate to achieve a better crosslinking effect, and meanwhile, carbonate mineralization bacteria are wrapped in the gel and fixed in the interior and the surface of the phosphogypsum-based lightweight aggregate, so that the encapsulation efficiency of the carbonate mineralization bacteria is effectively improved, the activity of the bacteria is ensured, a relatively stable living environment is provided for the carbonate mineralization bacteria, the temperature adaptation range of the bacterial strain is improved, the buffering capacity of the bacterial strain on acid-base change is also enhanced, and the self-repairing efficiency of the bacterial strain is effectively improved.
The invention is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the invention as claimed.
The bacillus subtilis used in the examples of the present invention was purchased from the Beijing organism collection under the number CMCC (B) 63501.
The Bacillus alcalophilus used in the examples of the present invention was purchased from Shanghai collection of microorganisms under the designation SHBCC D17302.
Bacillus sphaericus used in the examples of the present invention was purchased from Shanghai deposit microorganism center under the number ATCC 4525.
Bacillus curvatus used in the examples of the present invention was purchased from Shanghai collection microbiology technical center under the number SHBCC D10996Y 6.
The Bacillus cereus used in the examples of the present invention was purchased from Shanghai collection of microorganisms under the number DSM6307.
The Bacillus pseudofirmus used in the examples of the present invention was purchased from Beijing biological collection under the accession number ATCC 700159.
The bacillus thuringiensis adopted in the embodiment of the invention is purchased from Beijing biological collection center and has the number of CGMCC 1.16.
Bacillus licheniformis used in the examples of the present invention was purchased from Beijing biological collection under the number ATCC 11946.
Bacillus mucilaginosus adopted in the examples of the present invention was purchased from Shanghai preservation microorganism center under the number AS1.232.
Bacillus circulans used in the examples of the present invention were purchased from Shanghai collection of microorganisms under the accession number ATCC4516.
The Bacillus megaterium used in the examples of the present invention was purchased from Shanghai collection microorganism center under the number ACCC11107.
The boron-resistant lysine bacillus adopted in the embodiment of the invention is purchased from Shanghai preservation microbiological technology center and is numbered ATCCBAA-1146.
Phosphogypsum powder adopted by the invention is 200-300 meshes; the slag powder adopted by the invention is granulated blast furnace slag powder, is a high-quality mortar admixture, and is obtained by drying and grinding granulated blast furnace slag conforming to GB/T203 standard to obtain 1200-1340 mesh powder. The finely ground blast furnace slag, which is derived from molten iron slag quenched in water, can be excited by an alkali-exciting agent having a pH of 12 to 13. The slag powder grade used in the invention is S95. The steel slag powder is of a grade of 200-300 meshes.
The invention provides an application of phosphogypsum-based lightweight aggregate embedded with microorganisms in mortar or concrete, wherein the applicable temperature is 15-45 ℃ and the pH is 9-12.
Example 1
The embodiment provides phosphogypsum-based lightweight aggregate embedded with microorganisms, which comprises the following steps:
the preparation method of the phosphogypsum-based lightweight aggregate comprises the following steps:
(1) 1200g phosphogypsum powder and 800g slag powder are weighed and added into a stirrer to be stirred uniformly to obtain a mixture.
(2) Starting a disc granulator, setting the rotating speed to be 60r/min, firstly putting the mixture into the disc granulator, and then spraying 515g of alkali excitant into the disc granulator; operating for 20min at a rotating speed of 60r/min to obtain primary alkali-activated aggregate, wherein the alkali-activated agent is prepared from the following components in percentage by mass of 1.5:1 (sodium silicate modulus of 2) and sodium hydroxide (concentration of 5 mol/L).
(3) And (3) carrying out natural curing on the primary alkali-activated aggregate for 1d, and then carrying out constant temperature and constant humidity standard curing for 2d to obtain phosphogypsum-based lightweight aggregate P60-SC40, wherein the content of phosphogypsum powder is 60wt% and the content of slag powder is 40wt%. The natural curing temperature is 25 ℃ and the relative humidity is 55%; the temperature of the constant temperature and humidity standard curing is 20 ℃ and the relative humidity is 95%.
The process shown in fig. 1, the phosphogypsum-based lightweight aggregate embedded with the microorganism, comprises the following steps:
sterilizing phosphogypsum-based lightweight aggregate at 120 ℃ for 20min, cooling to room temperature, adding 1200g of sterilized phosphogypsum-based lightweight aggregate P60-SC40 into a sealed bottle containing 1700mL of cementing liquid (0.3 mol/L of calcium acetate solution and 18g/L of urea) for soaking for 12h, and drying at room temperature for 1h; then transferred into a compound bacteria fixing agent (the compound bacteria fixing agent comprises 850mL sodium alginate with the mass concentration of 4wt% and 850mL sodium alginate with the concentration of l 0) 9 CFU/mL carbonate mineralized bacteria liquid), drying in an oven to constant weight at 28 ℃ and +1bar for 12 hours, and obtaining phosphogypsum-based lightweight aggregate embedded with microorganisms, which is marked as A1.
The invention adopts a dilution plate counting method to prepare the carbonate mineralized bacteria liquid: the Bacillus pasteurisi was first cultivated in 4000mL of sterile UYE medium at 28℃and 170rpm for 72h to obtain an original bacterial solution. Centrifuging the original bacterial solution at 7000rpm for l0min to obtain bacterial balls, and re-suspending in sterile physiological saline to obtain bacterial balls with a concentration of l0 9 The CFU/mL carbonate mineralized bacteria liquid is stored at 4 ℃ for subsequent use; wherein the sterile UYE culture medium comprises 20g/L urea and 20g/L yeast extract.
Example 2
The embodiment provides phosphogypsum-based lightweight aggregate embedded with microorganisms, which comprises the following steps:
the preparation method of the phosphogypsum-based lightweight aggregate comprises the following steps:
(1) 1200g phosphogypsum powder, 700g slag powder and 100g steel slag powder are weighed and added into a stirrer to be uniformly stirred to obtain a mixture.
(2) Starting the disk granulator, setting the rotating speed to be55r/min, the mixture was put into a disk granulator before 525g Ca (OH) 2 Spraying the suspension into a disc granulator; operating at 55r/min for 15min to obtain primary alkali-activated aggregate, wherein Ca (OH) 2 The suspension is prepared by the following steps: the mass ratio of water is 1: 6.
(3) And (3) carrying out natural curing on the primary alkali-activated aggregate for 2d, and then carrying out constant temperature and constant humidity standard curing for 3d to obtain phosphogypsum-based lightweight aggregate P60-SC35-SP5, wherein the content of phosphogypsum powder is 60wt%, the content of slag powder is 35wt% and the content of steel slag powder is 5wt%. The natural curing temperature is 20 ℃ and the relative humidity is 60%; constant temperature and humidity standard curing is carried out at 19 ℃ and the relative humidity is 90%.
The process shown in fig. 1, the phosphogypsum-based lightweight aggregate embedded with the microorganism, comprises the following steps:
sterilizing phosphogypsum-based lightweight aggregate at 120 ℃ for 20min, cooling to room temperature, adding 1200g of sterilized phosphogypsum-based lightweight aggregate P60-SC35-SP5 into a sealing bottle containing 1800mL of cementing liquid (0.5 mol/L calcium chloride solution and 20g/L urea) for 8h, and drying at room temperature for 1h; then transferred into a compound bacteria fixing agent (the compound bacteria fixing agent comprises 900mL of xanthan gum with the mass concentration of 3wt% and 900mL of 10 8 CFU/mL carbonate mineralized bacteria liquid), drying in an oven to constant weight at 25 ℃ and +1.5bar for 24 hours, and obtaining phosphogypsum-based lightweight aggregate embedded with microorganisms, which is marked as A2.
The invention adopts a dilution plate counting method to prepare the carbonate mineralized bacteria liquid: firstly, culturing bacillus megatherium in 4000mL of sterile UYE culture medium at 27 ℃ and 170rpm for 48 hours to obtain an original bacterial liquid. Then centrifuging the original bacterial solution at 5000rpm for 10min to obtain bacterial balls, and placing into sterile physiological saline solution for resuspension to obtain bacterial balls with concentration of 10 8 The CFU/mL carbonate mineralized bacterial liquid is stored at 4 ℃ for subsequent use. Wherein the sterile UYE culture medium comprises 20g/L urea and 20g/L yeast extract.
Example 3
The embodiment provides phosphogypsum-based lightweight aggregate embedded with microorganisms, which comprises the following steps:
the preparation method of the phosphogypsum-based lightweight aggregate comprises the following steps:
(1) 1200g phosphogypsum powder, 600g slag powder and 200g steel slag powder are weighed and added into a stirrer to be uniformly stirred to obtain a mixture.
(2) Starting a disc granulator, setting the rotating speed to be 70r/min, firstly putting the mixture into the disc granulator, and then spraying 515g of alkali excitant into the disc granulator; and running for 18min at a rotating speed of 70r/min to obtain the primary alkali-activated aggregate, wherein the alkali-activated agent is sodium silicate (the modulus of the sodium silicate is 3).
(3) And (3) carrying out natural curing on the primary alkali-activated aggregate for 1d, and then carrying out constant temperature and constant humidity standard curing for 3d to obtain the phosphogypsum-based lightweight aggregate P60-SC30-SP10, wherein the content of phosphogypsum powder is 60wt%, the content of slag powder is 30wt% and the content of steel slag powder is 10wt%. Wherein the natural curing temperature is 27 ℃ and the relative humidity is 50%; the temperature of the standard curing under constant temperature and humidity is 21 ℃ and the relative humidity is 90%.
The process shown in fig. 1, the phosphogypsum-based lightweight aggregate embedded with the microorganism, comprises the following steps:
sterilizing phosphogypsum-based lightweight aggregate at 121 ℃ for 20min, cooling to room temperature, adding 1200g of sterilized phosphogypsum-based lightweight aggregate P60-SC30-SP10 into a sealing bottle containing 1900mL of cementing liquid (calcium lactate solution with the cementing liquid of 0.2mol/L and 21g/L urea), soaking for 12h, and drying at room temperature for 1h; then transferred into a compound bacteria fixing agent (the compound bacteria fixing agent comprises 950mL of acacia with the mass concentration of 5wt% and 950mL of acacia with the mass concentration of 10) 9 CFU/mL carbonate mineralized bacteria liquid), drying in an oven to constant weight at 25 ℃ and +1.2bar for 24 hours, and obtaining phosphogypsum-based lightweight aggregate embedded with microorganisms, which is marked as A3.
The invention adopts a dilution plate counting method to prepare the carbonate mineralized bacteria liquid: firstly, culturing bacillus cereus in 4000mL of sterile UYE culture medium at 26 ℃ and 200rpm for 48 hours to obtain an original bacterial liquid. Centrifuging the original bacterial solution at 4000rpm for 10min to obtain bacterial balls, and re-suspending in sterile physiological saline to obtain bacterial balls with concentration of 10 9 The CFU/mL carbonate mineralized bacterial liquid is stored at 4 ℃ for subsequent use. Wherein the sterile UYE medium comprises 20g/L urea and 20g/L yeastMother extract.
Example 4
The embodiment provides phosphogypsum-based lightweight aggregate embedded with microorganisms, which comprises the following steps:
the preparation method of the phosphogypsum-based lightweight aggregate comprises the following steps:
(1) 1400g phosphogypsum powder and 600g slag powder are weighed and added into a stirrer to be stirred uniformly to obtain a mixture.
(2) Starting a disc granulator, setting the rotating speed to be 65r/min, firstly putting the mixture into the disc granulator, and then spraying 525g of alkali excitant into the disc granulator; and running at a rotating speed of 65r/min for 17min to obtain the primary alkali-activated aggregate, wherein the alkali-activated agent is a mixture of sodium sulfate solution (1 mol/L) and sodium hydroxide solution (5 mol/L) (the molar ratio is 1:5).
(3) Natural curing is carried out on the primary alkali-activated aggregate for 2d, and then constant temperature and constant humidity standard curing is carried out for 2d; the phosphogypsum-based lightweight aggregate P70-SC30 is obtained, wherein the content of phosphogypsum powder is 70wt% and the content of slag powder is 30wt%. The natural curing temperature is 23 ℃ and the relative humidity is 55%; the temperature of the constant temperature and humidity standard curing is 20 ℃ and the relative humidity is 95%.
The process shown in fig. 1, the phosphogypsum-based lightweight aggregate embedded with the microorganism, comprises the following steps:
sterilizing phosphogypsum-based lightweight aggregate at 121deg.C for 20min, cooling to room temperature, adding 1200g sterilized phosphogypsum-based lightweight aggregate P70-SC30 into composite bacterial immobilizing agent (the composite bacterial immobilizing agent comprises 900mL gelatin with mass concentration of 4wt% and 900mL gelatin with concentration of 10) 8 CFU/mL carbonate mineralized bacteria solution) at 24 ℃, +1.3bar and kept for 24 hours, and dried at room temperature for 1 hour; transferring into a sealing bottle containing 1800mL of cementing liquid (calcium lactate solution with the cementing liquid of 0.4mol/L and urea with the cementing liquid of 19 g/L) for soaking for 24 hours, and drying in an oven to constant weight to obtain the phosphogypsum-based lightweight aggregate embedded with the microorganism, which is marked as A4.
The invention adopts a dilution plate counting method to prepare the carbonate mineralized bacteria liquid: firstly, bacillus pseudofirmus is cultured in 4000mL of sterile UYE culture medium at 29 ℃ and 170rpm for 72 hours, and original bacterial liquid is obtained. Then the original bacterial liquid is processed at 6000rpm Centrifuging for 10min to obtain pellet, and placing into sterile physiological saline for resuspension to obtain a concentration of 10 8 The CFU/mL carbonate mineralized bacterial liquid is stored at 4 ℃ for subsequent use. Wherein, the sterile UYE liquid culture medium comprises 20g/L urea and 20g/L yeast extract.
Comparative example 1
The comparative example provides a method for preparing phosphogypsum-based lightweight aggregate, comprising the following steps:
(1) 1200g phosphogypsum powder and 800g steel slag powder are weighed and added into a stirrer to be stirred uniformly to obtain a mixture.
(2) The disk granulator was started, the rotation speed was set at 60r/min, the mixture was put into the disk granulator, and 515g of Ca (OH) was added to the disk granulator 2 Spraying the suspension into a disc granulator; operating at a rotation speed of 60r/min for 20min to obtain primary alkali-activated aggregate, wherein Ca (OH) 2 The suspension is prepared by the following steps: the mass ratio of water is 1: 6.
(3) Natural curing is carried out on the primary alkali-activated aggregate for 1d, and then constant temperature and constant humidity standard curing is carried out for 2d; the phosphogypsum-based lightweight aggregate P60-SP40 is obtained, wherein the content of phosphogypsum powder is 60wt% and the content of steel slag powder is 40wt%. The natural curing temperature is 25 ℃ and the relative humidity is 55%; the temperature of the constant temperature and humidity standard curing is 20 ℃ and the relative humidity is 95%.
Comparative example 2
The comparative example provides a method for preparing phosphogypsum-based lightweight aggregate, comprising the following steps:
(1) 1400g phosphogypsum powder, 500g slag powder and 100g cement are weighed and added into a stirrer to be uniformly stirred to obtain a mixture.
(2) Starting a disc granulator, setting the rotating speed to be 60r/min, firstly putting the mixture into the disc granulator, and then spraying 510g of water into the disc granulator; and running for 20min at the rotating speed of 60r/min to obtain the primary cold-bonded aggregate.
(3) Natural curing is carried out on the primary cold bonding aggregate for 1d, and then constant temperature and constant humidity standard curing is carried out for 2d; the phosphogypsum-based lightweight aggregate P70-SC25-C5 is obtained, wherein the content of phosphogypsum powder is 70wt%, the content of slag powder is 25wt% and the content of cement is 5wt%. The natural curing temperature is 25 ℃ and the relative humidity is 55%; constant temperature and humidity standard curing is carried out at 20 ℃ and the relative humidity is 95%.
Comparative example 3
The comparative example provides a method for preparing phosphogypsum-based lightweight aggregate, comprising the following steps:
(1) 1400g phosphogypsum powder, 300g fly ash and 300g slag powder are weighed and added into a stirrer to be uniformly stirred to obtain a mixture.
(2) The disk granulator was started, the rotation speed was set at 60r/min, the mixture was put into the disk granulator, and 515g of Ca (OH) was added to the disk granulator 2 Spraying the suspension into a disc granulator; operating at a rotation speed of 60r/min for 20min to obtain primary alkali-activated aggregate, wherein Ca (OH) 2 The suspension is prepared by the following steps: the mass ratio of water is 1: 6.
(3) Natural curing is carried out on the primary alkali-activated aggregate for 1d, and then constant temperature and constant humidity standard curing is carried out for 2d; the phosphogypsum-based lightweight aggregate P70-SC15-F15 is obtained, wherein the content of phosphogypsum powder is 70wt%, the content of fly ash is 15wt%, and the content of slag powder is 15wt%. The natural curing temperature is 25 ℃ and the relative humidity is 55%; constant temperature and humidity standard curing is carried out at 20 ℃ and the relative humidity is 95%.
Comparative example 4
The comparative example provides a method for preparing phosphogypsum-based lightweight aggregate, comprising the following steps:
(1) 1000g phosphogypsum powder, 600g slag powder and 400g steel slag powder are weighed and added into a stirrer to be uniformly stirred to obtain a mixture.
(2) The disk granulator was started, the rotation speed was set at 60r/min, the mixture was put into the disk granulator, and 515g of Ca (OH) was added to the disk granulator 2 Spraying the suspension into a disc granulator; operating at a rotation speed of 60r/min for 20min to obtain primary alkali-activated aggregate, wherein Ca (OH) 2 The suspension is prepared by the following steps: the mass ratio of water is 1: 6.
(3) Natural curing is carried out on the primary alkali-activated aggregate for 1d, and then constant temperature and constant humidity standard curing is carried out for 2d; the phosphogypsum-based lightweight aggregate P50-SC30-SP20 is obtained, wherein the content of phosphogypsum powder is 50wt%, the content of slag powder is 30wt%, and the content of steel slag powder is 20wt%. The natural curing temperature is 25 ℃ and the relative humidity is 55%; constant temperature and humidity standard curing is carried out at 20 ℃ and the relative humidity is 95%.
Experimental example 1
Phosphogypsum-based lightweight aggregate prepared in examples 1-4 of the present invention was prepared according to the lightweight aggregate and test method part 1: the light aggregate (GB/T17431.1-2010) was tested for apparent density, barrel compressive strength, classification, and water absorption, and the results are shown in Table 1.
TABLE 1 Performance test results of phosphogypsum-based lightweight aggregate
From the above table, it can be seen that the smaller the apparent density, the stronger the water absorption. The phosphogypsum-based lightweight aggregates prepared in comparative examples 1 and 4 have higher steel slag content, resulting in low compressive strength of the aggregate cylinder; comparative example 2 uses phosphogypsum-based cold-bonded aggregate containing 5wt% cement, resulting in lower compressive strength of the cylinder, indicating that phosphogypsum-based cold-bonded aggregate containing 5wt% cement is not as fast as the alkali-activated aggregate of the invention is hydrated and hardened, and the strength development is slow; in comparative example 3, 15wt% fly ash was used, and the barrel compressive strength of the aggregate was significantly reduced.
Experimental example 2
The microbial-embedded phosphogypsum-based lightweight aggregate and the phosphogypsum-based lightweight aggregate without the embedded microorganisms are adopted for pre-experiment, and a flow chart of the microbial-embedded phosphogypsum-based lightweight aggregate bacterial activity test and seepage condition is shown in figure 2.
The bacterial activity test of the phosphogypsum-based lightweight aggregate embedded in the phosphogypsum-based lightweight aggregate is discussed, and the specific detection method comprises the following steps: grinding 7g of microorganism-embedded phosphogypsum-based lightweight aggregate or non-microorganism-embedded phosphogypsum-based lightweight aggregate to fineness less than 1.18mm by using a mortar, putting into 30mL of 20g/L urea solution for urease activity test, and detecting the urease activity and pH change of the microorganism-embedded or non-microorganism-embedded phosphogypsum-based lightweight aggregate at 0h, 6h, 12h, 18h, 24h, 30h and 36h respectively, wherein the results are shown in tables 2-5; the gel is insoluble in water, isolates the external environment influence, and can not test the urease activity if not broken;
The preparation method of the phosphogypsum-based lightweight aggregate without embedding microorganisms comprises the following steps: taking 14g of the dried phosphogypsum-based lightweight aggregate prepared in examples 1-4, sterilizing at 120 ℃ for 20min, soaking in 100mL of 0.5M calcium acetate solution in a sealed bottle for 12h, and drying at room temperature for 1h; transfer to 100mL volume ratio 1:1 is mixed solution of sterilized water and 5wt% sodium alginate, and is dried to constant weight in an oven after being kept at 28 ℃ and +1bar for 12 hours, thus obtaining phosphogypsum-based lightweight aggregate without embedded microorganisms, which are respectively marked as B1-B4. Of these 7g were used for strain activity testing and the other 7g were used for leakage condition experiments.
Table 2 results of the test for the activity of the microorganism-embedded phosphogypsum-based lightweight aggregate urease prepared in the examples
Table 3 pH Change of microorganism-embedded phosphogypsum-based lightweight aggregate prepared in examples
TABLE 4 phosphogypsum-based lightweight aggregate urease Activity test results without microorganism embedded
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TABLE 5 pH Change of phosphogypsum-based lightweight aggregate without microorganism
As can be seen from Table 2, after 24 hours, A1, A2, A3 and A4 had urea decomposition concentrations of 17.5g/L, 17.6g/L, 18.8g/L and 18.7g/L, and 80% (minimum urea decomposition value/initial urea concentration. Times.100%) or more of A1-A4 had urea decomposed; as can be seen from Table 4, B1-B4 did not embed carbonate mineralizers, resulting in failure to decompose urea. The carbonate mineralizer adopted by the invention is urease bacteria, can generate urease, hydrolyzes urea into carbonate through metabolic process, and is used for repairing mortar or concrete cracks.
The pH values of B1-B4 (no bacteria control sample) are respectively 10.9, 10.7 and 10.8 (table 5) at 0h, the pH values of A1-A4 solutions at 0h are respectively 10.86, 10.68, 10.73 and 10.82, the addition of carbonate mineralization bacteria has an effect on the pH values of the solutions of all phosphogypsum-based lightweight aggregate carriers, after soaking for 24h, the pH values of A1-A4 are buffered to 9.70-9.79 (table 3), and the pH values are buffered due to the activity of the encapsulated strains, so that the growth and fermentation levels of the strains are suitable, and the bacterial bodies have certain self-regulating capability and stronger alkali resistance.
Bacterial leakage test was performed using phosphogypsum-based lightweight aggregate embedded with microorganisms, cell concentration was measured before injecting the cell suspension into the phosphogypsum-based lightweight aggregate, and then the initial cell number was converted from cell CFU/mL to cell CFU/g phosphogypsum-based lightweight aggregate by dividing the cell number by the mass of the phosphogypsum-based lightweight aggregate, and the value was recorded as L1. The phosphogypsum-based lightweight aggregate embedded with the microorganism is soaked in demineralized water and vibrated, the cell concentration in the water is tested by a flow cytometer, and then the cell number is converted from cell CFU/mL to cell CFU/g phosphogypsum-based lightweight aggregate by dividing the cell number by the mass of phosphogypsum-based lightweight aggregate, and the numerical value is recorded as L2. Thus, leak percentage = L2/L1 x 100%.
The method comprises the following specific steps: after 7g of phosphogypsum-based lightweight aggregate embedded with microorganisms was immersed in 30mL of demineralized water, the mixture was placed on a shaking table of 120r/min and vibrated for 1 hour, and the bacterial concentration was measured by a flow cytometer, and the average leakage rate of 3 times is shown in Table 6.
Table 6 test results of phosphogypsum-based lightweight aggregate bacterial leakage test with microorganism embedded therein
In all cases, the amount of each set of phosphogypsum-based lightweight aggregates in the experiments of viability and leakage after embedding bacteria was set to 7g, and the amount of the carbonate mineralization bacteria embedded in the phosphogypsum-based lightweight aggregates was determined by the water absorption rate of the phosphogypsum-based lightweight aggregates in table 1, and the higher the water absorption rate, the higher the porosity, the more the carbonate mineralization bacteria can be embedded. As can be seen from table 6, the leakage rate of the encapsulated bacteria is 13% -17%, and the leakage rates of A1, A2, A3, A4 are relatively similar, because the phosphogypsum-based lightweight aggregate embedding the microorganisms significantly reduces the effect of bacterial leakage caused by the pore structure and pore size of the phosphogypsum-based lightweight aggregate. The size of the carbonate mineralization bacteria is 2-3 mu m, the high porosity of the phosphogypsum-based lightweight aggregate is an ideal shelter for the carbonate mineralization bacteria (the pore size ranges of A1, A2, A3 and A4 are respectively 1-6 mu m, 2-7 mu m, 4-7 mu m and 3-10 mu m, the Mercury Intrusion Porosimetry (MIP) is respectively 24%, 25%, 28% and 30%, and the pore sizes of 4-10 mu m are respectively 60%, 63%, 69% and 72%).
A1, A2, A3 and A4 have high bacterial activity and low leakage rate, and are characterized in that the gel has good biocompatibility, is insoluble in water, has mild adhesive tape forming components (the gel rapidly reacts with calcium ions adsorbed on phosphogypsum-based lightweight aggregate to wrap the bacteria) and firmly fixes the gel and the calcium ions on the inside and the surface of the lightweight aggregate, so that the bacteria are not easy to run off, and the self-repairing effect of the mortar is improved.
Experimental example 3
In order to evaluate the biomineralization property of phosphogypsum-based lightweight aggregate embedded with microorganisms, the preparation method of the mortar test piece of the invention tests self-repairing capability through crack surface observation and crack width measurement, and the preparation method of the mortar comprises the following steps: A1-A4 are brought to a saturated surface dry state prior to use; 698kg/m of 3 Sand, 765kg/m 3 Examples1-4 or phosphogypsum-based lightweight aggregate B1-B4 without embedded microorganism prepared by 1-4 and 738.24kg/m 3 Phosphogypsum-based cementing material is stirred in a mortar stirrer for 0.5min, and then 215.32kg/m is added 3 The water was stirred for 2min, poured into a 100mm×50mm (d×h) cylindrical mold, and shaken on a shaking table for 20s to obtain good flowability and compactibility. Wrapping the sample with a plastic film and a mold, preventing from drying, curing for 24 hours at room temperature, demolding, storing in a standard curing chamber, and curing for 28 days until the test age, so as to prepare mortar test pieces C1-C4 (corresponding to A1-A4) and D1-D4 (corresponding to B1-B4); wherein the phosphogypsum-based cementing material comprises 307.6kg/m 3 Phosphogypsum powder 276.84kg/m 3 Slag powder, 30.76kg/m 3 The common Portland cement, all test pieces are manufactured into cracks by adopting a splitting method (shown in figure 3), the split test pieces are fastened by using a self-locking metal belt, silica gel films with different thicknesses are embedded into the cracks to form cracks with different widths, and healing conditions (curing is carried out in a standard curing room at the temperature of 18-22 ℃ and the humidity of 90-100%) after 0d, 14d and 28d are respectively tested, and the results are shown in the table 7 and figure 4.
TABLE 7 test results of self-repairing ability of mortar test pieces
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From Table 7 and FIG. 4, it was found that the initial crack width was 0.31mm to 1.24mm, the gel was isolated from the external environment, the carbonate mineralizing bacteria were embedded in the pores and the surface of the phosphogypsum-based lightweight aggregate, and when the crack occurred in the mortar, the strain was released for crack repair. The crack width gradually decreases with the increase of healing time, caCO 3 The number of crystals increases and single-layer to multi-layer fills the entire crack with tight bond strength. At the same time, the hydration of the slag powder creates a new crystal-matrix interface (flocculent C-S-H gel and needle-like ettringite) that helps the crystals bridge the cracks again. Such a healing mechanism may enhance the flexural rigidity of the concrete sample because of the crystallized CaCO 3 The continuity of the fracture interface is enhanced. Meanwhile, after standard curing for 28 days, uniaxial pressure resistanceThe degree is substantially fully recovered. The cracks of D1, D2, D3 and D4 were not completely repaired, and the crack widths were 1.17mm, 0.48mm, 0.15mm and 0.71mm, respectively, because they were not completely repaired without the addition of mineralization bacteria. The slight healing of the cracks of D1-D4 occurs because the slag in the self-repairing mortar containing slag powder has higher activity and high CaO content, which is beneficial to the precipitation of calcite. In addition, due to hydration reaction of unhydrated cement particles in the mortar and external water, the carbonation process of calcium hydroxide can occur in cracks with smaller width, and calcium carbonate precipitation is generated.
From the 28D compressive strength of mortar test pieces C1 to C4 (corresponding to A1 to A4) and D1 to D4 (corresponding to B1 to B4), it can be seen that phosphogypsum-based lightweight aggregates obtained by embedding carbonate mineralization bacteria such as Bacillus megaterium, bacillus cereus, bacillus pseudosolidus and the like with gel are compatible with a gelling system, and the strength and durability of the mortar mixture can be improved.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. The preparation method of the phosphogypsum-based lightweight aggregate is characterized by comprising the following steps:
(1) Mixing phosphogypsum powder, slag powder and steel slag powder to obtain a mixture;
(2) Placing the mixture into a granulating device, spraying an alkali-exciting agent, and stirring to obtain primary alkali-exciting aggregate;
(3) Natural curing and constant temperature and humidity standard curing are carried out on the primary alkali-activated aggregate, so that the natural curing agent is obtained;
the mass ratio of phosphogypsum powder to slag powder to steel slag powder is 60-70:30-40:0-10.
2. The method for preparing phosphogypsum-based lightweight aggregate according to claim 1, wherein the mass ratio of the mixture to the alkali-activator is 1:0.25-0.51;
and/or the alkali-activator is at least one of the following solutions:
the calcium hydroxide suspension is prepared from the following components: the mass ratio of water is 1:5-6 configuration;
sodium silicate with modulus of 2.5-3.1;
the mass ratio of the sodium silicate to the sodium hydroxide solution is 0.3-1.5:1, wherein before mixing, the sodium silicate has a water glass modulus of 0.947-3.23 and a sodium hydroxide concentration of 4-6 mol/L;
the molar ratio of the sodium sulfate solution to the sodium hydroxide solution is 1:4-6, wherein before mixing, the concentration of the sodium sulfate solution is 0.8mol/L-1mol/L, and the concentration of the sodium hydroxide solution is 4mol/L-6mol/L.
3. The method for preparing phosphogypsum-based lightweight aggregate in accordance with claim 1, wherein in the step (2), the stirring comprises stirring at 55r/min-75r/min for 15min-20min;
and/or in the step (3), the temperature of the natural curing is 20-30 ℃, the relative humidity is 35-65%, and the curing time is 1d-2d;
and/or the temperature of the constant temperature and humidity standard curing is 19-21 ℃, the relative humidity is 85-95%, and the curing time is 2-3 d.
4. Phosphogypsum-based lightweight aggregate, prepared by the preparation method of any one of claims 1-3.
5. The preparation method of the phosphogypsum-based lightweight aggregate with embedded microorganisms is characterized by comprising the following steps: pretreating phosphogypsum-based lightweight aggregate prepared by the preparation method of any one of claims 1 to 3 or phosphogypsum-based lightweight aggregate of claim 4; and respectively soaking the pretreated phosphogypsum-based lightweight aggregate in cementing liquid and a composite bacterial fixing agent to obtain the phosphogypsum-based lightweight aggregate.
6. The method for preparing a microbial-embedded phosphogypsum-based lightweight aggregate according to claim 5, wherein the pretreatment step comprises: sterilizing the phosphogypsum-based lightweight aggregate, wherein the sterilization temperature is 120-121 ℃ and the sterilization time is 20-40 min.
7. The method for preparing phosphogypsum-based lightweight aggregate of gel-embedded microorganism according to claim 5, wherein the cementing liquid contains 17g/L-23g/L urea and 0.1mol/L-0.5mol/L calcium salt solution;
and/or the calcium salt is at least one of calcium acetate, calcium nitrate, calcium chloride and calcium lactate;
and/or the ratio of the mass of the pre-treated phosphogypsum-based lightweight aggregate to the volume of the cementing liquid is 0.6-0.74:1, the proportional relationship is g/mL;
and/or soaking time in the cementing liquid is 8-24 h.
8. The method for preparing phosphogypsum-based lightweight aggregate embedded with microorganisms according to claim 5, wherein the composite bacterial solidifying agent comprises a gel aqueous solution and a carbonate mineralization bacterial liquid;
and/or the gel is at least one of sodium alginate, acacia, xanthan gum, gelatin, carrageenan and sodium silicate;
and/or the mass fraction of gel in the gel aqueous solution is 3-5 wt%;
and/or the carbonate mineralization bacteria are at least one of bacillus subtilis, bacillus alcalophilus, bacillus sphaericus, bacillus curvatus, bacillus coleus, bacillus pseudofirmus, bacillus thuringiensis, bacillus licheniformis, bacillus mucilaginosus, bacillus circulans, bacillus megaterium and bacillus boro-resistant lysine;
And/or the concentration of the carbonate mineralization bacterial liquid is 10 8 CFU/mL-l0 9 CFU/mL；
And/or, the volume ratio of the gel aqueous solution to the carbonate mineralization bacterial liquid is 1:1-2;
and/or the ratio of the mass of the pretreated phosphogypsum-based lightweight aggregate to the volume of the composite microbial fixative is 0.6-0.8:1, the proportional relationship is g/mL;
and/or, soaking the composite immobilized microbial agent comprises the following steps: soaking for 12-24 h at 23-28 ℃ and 0.7-1.5 bar;
and/or, the preparation method of the carbonate mineralization bacterial liquid comprises the following steps: selecting carbonate mineralized bacteria single colony, and culturing at 26-29 deg.c and 170-220 rpm for 48-72 hr to obtain original bacteria liquid; centrifuging the original bacterial liquid, placing the bacterial liquid in sterile physiological saline for resuspension to obtain carbonate mineralized bacterial liquid, and preserving the carbonate mineralized bacterial liquid at the temperature of 4 ℃ for later use.
9. An phosphogypsum-based lightweight aggregate embedded with microorganisms, prepared by the preparation method of any one of claims 5 to 8.
10. The microorganism-embedded phosphogypsum-based lightweight aggregate prepared by the preparation method of any one of claims 5 to 8, or the application of the microorganism-embedded phosphogypsum-based lightweight aggregate in self-repairing mortar or concrete.
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