GB2454490A - Method and composition for removal of hydrogen sulphide from gas - Google Patents
Method and composition for removal of hydrogen sulphide from gas Download PDFInfo
- Publication number
- GB2454490A GB2454490A GB0721912A GB0721912A GB2454490A GB 2454490 A GB2454490 A GB 2454490A GB 0721912 A GB0721912 A GB 0721912A GB 0721912 A GB0721912 A GB 0721912A GB 2454490 A GB2454490 A GB 2454490A
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- GB
- United Kingdom
- Prior art keywords
- ferric hydroxide
- reactor
- ferric
- gas
- iron
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 67
- 239000007789 gas Substances 0.000 title claims abstract description 49
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 title claims abstract description 44
- 239000000203 mixture Substances 0.000 title claims abstract description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 96
- 229960004887 ferric hydroxide Drugs 0.000 claims abstract description 73
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims abstract description 73
- 229910052742 iron Inorganic materials 0.000 claims abstract description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 38
- 230000008569 process Effects 0.000 claims abstract description 26
- 239000010801 sewage sludge Substances 0.000 claims abstract description 19
- 239000007787 solid Substances 0.000 claims abstract description 16
- 238000011065 in-situ storage Methods 0.000 claims abstract description 12
- 230000029087 digestion Effects 0.000 claims abstract description 11
- 239000001257 hydrogen Substances 0.000 claims description 31
- 229910052739 hydrogen Inorganic materials 0.000 claims description 31
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 30
- 238000011282 treatment Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 9
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 8
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 8
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 7
- 229910021653 sulphate ion Inorganic materials 0.000 claims description 7
- 238000004065 wastewater treatment Methods 0.000 claims description 4
- 235000014413 iron hydroxide Nutrition 0.000 abstract 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 abstract 1
- 239000010802 sludge Substances 0.000 description 18
- 239000000243 solution Substances 0.000 description 15
- 239000000126 substance Substances 0.000 description 11
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 10
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 8
- 229910052952 pyrrhotite Inorganic materials 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 238000000746 purification Methods 0.000 description 6
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000002203 pretreatment Methods 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 229910002588 FeOOH Inorganic materials 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 239000005864 Sulphur Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000004411 aluminium Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 3
- 229910021502 aluminium hydroxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 239000000701 coagulant Substances 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910000000 metal hydroxide Inorganic materials 0.000 description 3
- 150000004692 metal hydroxides Chemical class 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 238000005200 wet scrubbing Methods 0.000 description 3
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 239000006096 absorbing agent Substances 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- NFMAZVUSKIJEIH-UHFFFAOYSA-N bis(sulfanylidene)iron Chemical compound S=[Fe]=S NFMAZVUSKIJEIH-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 229910052793 cadmium Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000002738 chelating agent Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000003651 drinking water Substances 0.000 description 2
- 235000020188 drinking water Nutrition 0.000 description 2
- 238000005203 dry scrubbing Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000000855 fermentation Methods 0.000 description 2
- 230000004151 fermentation Effects 0.000 description 2
- 229910001447 ferric ion Inorganic materials 0.000 description 2
- 229910001448 ferrous ion Inorganic materials 0.000 description 2
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 101100352919 Caenorhabditis elegans ppm-2 gene Proteins 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000223935 Cryptosporidium Species 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 229910052598 goethite Inorganic materials 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000003864 humus Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000000797 iron chelating agent Substances 0.000 description 1
- 229940075525 iron chelating agent Drugs 0.000 description 1
- 150000002506 iron compounds Chemical class 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- FLTRNWIFKITPIO-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe] FLTRNWIFKITPIO-UHFFFAOYSA-N 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052976 metal sulfide Inorganic materials 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229920000867 polyelectrolyte Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000003516 soil conditioner Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- -1 sulphide compound Chemical class 0.000 description 1
- 239000004291 sulphur dioxide Substances 0.000 description 1
- 235000010269 sulphur dioxide Nutrition 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1412—Controlling the absorption process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
- B01D53/1468—Removing hydrogen sulfide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1493—Selection of liquid materials for use as absorbents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/52—Hydrogen sulfide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/02—Biological treatment
- C02F11/04—Anaerobic treatment; Production of methane by such processes
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
- C12M1/00—Apparatus for enzymology or microbiology
- C12M1/107—Apparatus for enzymology or microbiology with means for collecting fermentation gases, e.g. methane
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
- C12M21/00—Bioreactors or fermenters specially adapted for specific uses
- C12M21/04—Bioreactors or fermenters specially adapted for specific uses for producing gas, e.g. biogas
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
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- C12M43/00—Combinations of bioreactors or fermenters with other apparatus
- C12M43/08—Bioreactors or fermenters combined with devices or plants for production of electricity
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
- C12M47/00—Means for after-treatment of the produced biomass or of the fermentation or metabolic products, e.g. storage of biomass
- C12M47/18—Gas cleaning, e.g. scrubbers; Separation of different gases
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P5/00—Preparation of hydrocarbons or halogenated hydrocarbons
- C12P5/02—Preparation of hydrocarbons or halogenated hydrocarbons acyclic
- C12P5/023—Methane
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/604—Hydroxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/05—Biogas
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/02—Odour removal or prevention of malodour
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/20—Sludge processing
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
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- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Wood Science & Technology (AREA)
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- Bioinformatics & Cheminformatics (AREA)
- Biotechnology (AREA)
- Analytical Chemistry (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Genetics & Genomics (AREA)
- General Health & Medical Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Biochemistry (AREA)
- Microbiology (AREA)
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- Molecular Biology (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Medicinal Chemistry (AREA)
- Treatment Of Sludge (AREA)
Abstract
A method for the removal of hydrogen sulphide from a gas comprises the steps of (i) contacting the gas with ferric hydroxide in water within a reactor under anaerobic conditions at a suitable pH and (ii) maintaining the ferric hydroxide concentration in the reactor at a predetermined value. The gas may be biogas generated during the digestion process of sewage sludge, and may be contacted with the iron hydroxide in situ. The pH may range from 5.5 to 9.0. The concentration of the ferric hydroxide in the reactor may by at least 5g/m3 and maintained by feeding additional amounts into the reactor at least once every 60 days. Also disclosed is a composition for use with the method which comprises a solution of ferric hydroxide in water wherein the solution comprises at least 8% ferric hydroxide expressed as iron on a dry basis and a minimum of 0.5% solids on a weight/volume basis.
Description
MATERIAL AND METHOD
The present invention relates to a method for the removal of hydrogen suiphide from a gas, particularly but not limited to for example the in situ removal of hydrogen suiphide from a biogas during the digestion process of sewage sludge and the like.
The digestion of sewage sludge produces useful biogas that can be used to generate hot water for process heating requirements. Until recently, surplus biogas produced in such processes was disposed of by simply burning in flare stacks. However, concerns over global warming have provided a significant economic stimulus to utilise the generation of biogas in more useful applications, for example as a resource for generating electricity.
Unfortunately, there exists a significant barrier to the utilisation of biogas in combined heat and power, or co-generation plants due to the high levels of hydrogen sulphide commonly associated with the biogas.
Hydrogen sulphide is a major problem as it is dangerous to health; corrosive to gas handling equipment and the product of combustion of hydrogen sulphide, namely sulphur dioxide is harmful to the environment. The removal of hydrogen sulphide from S..
generated biogas is however necessary in order to reduce environmental emissions and reduce engine maintenance costs. Therefore, whilst biogas clean-up' involves financial
S S
costs for the operator, it is essential for the biogas supply to conform to the requirements laid down by the engine manufacturer and/or to achieve emission standards set by industry regulators.
Hydrogen sulphide removal from biogas is commonly carried out as a pre-treatment, that is, after the production of the biogas but before its utilisation. Current pre-
I
treatment processes include a number of methods of removing or stripping hydrogen sulphide from gas streams, involving both wet and dry scrubbing techniques.
An early solid chemical treatment for hydrogen suiphide (H2S) removal, which was employed widely for coke-oven gas, was the use of an iron sponge'. In this treatment, hydrogen sulphide present within the gas reacted with the iron sponge' to form iron sulphide. This process achieved clean-up efficiencies of up to 99.98 per cent.
Furthermore, the spent adsorption beds resulting from the process could be re-activated by air injection, which converted the iron sulphide back into iron oxide and elemental sulphur.
Activated carbon filters (in the form of powder, granules or fibres) have also been used for the physical adsorption of hydrogen suiphide (H2S) (in addition to water, carbon dioxide and halogenated compounds). The carbon filters are most effectively used for polishing' gases after other treatment(s). However, the high cost of filter replacement or regeneration and the associated cost of disposing of spent carbon means that such schemes are too expensive for biogas clean-up operations for hydrogen sulphide.
S S..
::::* Chemicals used in the wet scrubbing of hydrogen suiphide (H2S) can be solid or liquid, and may be applied in either batch contactor towers or alternatively injected directly into a gas pipeline. The chemical by-products of the reaction are usually :::: separated and disposed of as a waste. In chemical clean-up' procedures the active * chemical is often consumed and the absorbent can often be regenerated. For the large-*..
S
scale treatment of natural gas, water-soluble alkanolamines are often employed to selectively absorb hydrogen sulphide (H2S) and carbon dioxide (C02). The biogas is purified via contact with the amine solution in an absorber under high pressure. The resultant solution is then released from absorbers under low pressure, which allows any dissolved hydrocarbons that are usually passed to the fuel gas system to escape. The amine solution is then regenerated by contact with steam in a stripping column; that is, the solvent is raised to its boiling point (110°C) and stripped by the steam.
The use of ferric iron in water systems for the removal of hydrogen sulphide from gases and liquids has also been previously described. However, since ferric iron is not soluble in water at the correct pH of application, the iron compounds are normally utilised in conjunction with for example a chelating agent or as a catalyst. For example, Thompson (1980) described the catalytic removal of hydrogen sulphide from gases in an oxidation-reduction process using a water-soluble ferric iron salt and at least two water-soluble iron-chelating agents. Similarly, Tajiri et al. (1985) proposed contacting a gas with a solution of ferric ions and ferrous ions wherein the solution further contained ethylenediamine tetraacetic acid and triethanolamine. Whilst the removal of sulphide from water could be achieved using a solution of non-chelated iron, this process involved the liquid phase oxidation of the dissolved hydrogen sulphide to sulphur by means of dissolved oxygen (Hardison, 1994). In yet another example of an iron- based process for catalytic oxidation of a sulphide compound from a gas, Rai (1999) promoted the use a *...
*..*. biologically assisted redox system with a ferric compound and at least one organic :" chelating agent capable of holding ferric and ferrous ions in solution.
I
It is apparent from the foregoing that the pre-treatment of biogas with dry scrubbing techniques involves using expensive chemicals that generate large volumes of wastes. On the other hand, wet-scrubbing techniques involve highly complicated process technologies that are more suitable for very large scale industrial operations. In many cases, the pre-treatment involves compressing and recirculation of large volumes of a potentially explosive gas. It is therefore desirable for the formation of hydrogen
S
sulphide (H2S) to either be prevented or alternatively for the gas removed in situ.
Currently, there are no known commercial processes for which the removal of hydrogen suiphide (H2S) takes place in situ. The main difficulty associated with any in situ reactions to remove hydrogen sulphide is the unknown consequences of introducing new reactants such as those already mentioned above into for example a digestion process that generates hydrogen sulphide (H2S). Nevertheless, it is known that some workers have attempted to remove hydrogen suiphide (H2S) in situ by dosing digesters with a solution of ferric chloride (FeCI3). Such attempts have not however resulted in a successful application either because the technique was found to be inefficient or because the application was not cost effective. Furthermore, some workers have suggested the use of water sludge for the in situ removal of hydrogen sulphide (H2S) but to date no detail of such processes are available and no successful application has been reported.
It is therefore an aim of the present invention to provide a method for the removal of hydrogen suiphide from a gas. More particularly it is an aim of the present invention to provide a method for the in situ removal of hydrogen sulphide from a biogas during the *. digestion process of sewage sludge and the like. Such a method would overcome the *.: disadvantages of methods described prior hereto. I... *
It is a further aim of the present invention is provide a low cost chemical composition or reagent suitable for use in the removal of hydrogen sulphide from a gas, more particularly for the in situ removal of hydrogen sulphide from a biogas during the digestion process of sewage sludge and the like. Such a chemical composition or reagent being safe and yet simple to use and can be disposed off readily after use.
Therefore according to a first aspect of the present invention there is provided a method suitable for the removal of hydrogen sulphide from a gas, the method comprising the steps of: (i) contacting the gas with ferric hydroxide in water within a reactor under anaerobic conditions at a suitable pH; and (ii) maintaining the ferric hydroxide concentration in said reactor at a pre-determined value.
In accordance with the present invention the hydrogen suiphide is removed form a biogas wherein the biogas is produced for example during a water or waste water treatment process. The method of the present invention finds particular application however in the removal of hydrogen suiphide from a gas preferably a biogas generated during the digestion process of sewage sludge.
Also in the method of the present invention the ferric hydroxide is contacted with the gas or biogas in situ.
It is desirable for the efficiency of the method for the pH of the system in the ***, reactor to be maintained in a range of between 5.5 and 9.0, more preferably between pH *..
6.0 and 8.0, and most preferably between pH 7.0 and 8.0.
It is also preferred that the minimum ferric hydroxide concentration in the reactor is at least 5g/m3 expressed as the concentration of iron, more preferably at least 20g1m3 expressed as the concentration of iron.
Likewise, it is preferred that the maximum ferric hydroxide concentration in the reactor is at least 500g/m3 expressed as the concentration of iron, more preferably at least I,000g/m3 expressed as the concentration of iron.
The ferric hydroxide concentration in the reactor is preferably maintained at a pre-determined value by feeding the reactor with ferric hydroxide at least once every 60 days, preferably at least once every 15 days.
More preferably the ferric hydroxide concentration in the reactor is maintained at a pre-determined value by feeding the reactor with ferric hydroxide continuously.
With regard to the ferric hydroxide, the ferric hydroxide is preferably derived from ferric chloride or ferric sulphate in a water purification application and most importantly, the ferric hydroxide can be recovered when the application is complete.
According to a second aspect of the present invention there is provided a composition suitable for the removal of hydrogen suiphide from a gas, wherein the composition comprises: a solution of ferric hydroxide in water wherein the solution comprises at least 8% femc hydroxide expressed as iron on a dry basis; and a minimum of 0.5% solids on weight/volume basis.
It is more preferred that the solution of ferric hydroxide in water comprises at least 15% femc hydroxide expressed as iron on a dry basis, and most preferred that the solution comprises at least 20% femc hydroxide expressed as iron on a dry basis.
Furthermore, it is preferred that the solution comprises a minimum of 2% solids on weight/volume basis.
S
Finally, according to a third aspect of the present invention there is provided the use of a composition according to the second aspect of the present invention wherein either ferric chloride or ferric sulphate in a water or wastewater treatment process
S
followed by recovering the resulting ferric hydroxide as a sludge, and wherein the sludge contains a minimum of 0.5% solids on wlv basis.
More preferably the use of the composition can be applied for the removal of hydrogen sulphide from a gas, and most preferably the gas is a biogas and the biogas is generated during the digestion process of sewage sludge.
Furthermore, the ferric hydroxide is derived from ferric chloride and/or ferric sulphate and the most importantly the ferric hydroxide is recoverable.
Water sludge is produced in abundance by the water industry. It is a by-product that arises from the use of heavy metal salts (both chloride and sulphate) for water treatment, particularly for colour and cryptosporidium removal applications. Aluminium and iron are the most commonly used coagulant chemicals in water purification. When such a metal salt is dissolved in water positively charged metal-ions are generated which attract impurities in the water such as colloids, humus and suspended particles which are all negatively charged. At the same time metal hydroxide flocs are formed by hydrolysis.
Impurities are captured by the flocs and a sludge consisting of metal hydroxide and p..
impurities is formed. Practically all coagulant added during water purification treatments remains in the sludge. The coagulant content of sludge is typically between 100 to 300 kg metal/tonne dry solids. The dry solids content of drinking water sludge is typically :: only about 0.1%. By adding a polyelectrolyte followed by sedimentation it is possible to raise the dry solids content to about 3.0%. By performing further mechanical dewatering, the dry solids content of the drinking water sludge can be further increased to a level of 5 to 20 % (as a slurry or cake). The water sludge is a waste material and its disposal normally incurs a considerable cost to the operator. Dewatered sludge may be disposed of in land fill sites but is often more commonly disposed of by means of utilisation as a soil conditioner in agriculture. Untreated water sludge may also be disposed of by discharging into the municipal sewerage networks.
Although the chemical formula for ferric hydroxide is often written in the literature as Fe(OH)3, this form is not found in nature. Ferric hydroxide is also known as ferric hydroxide oxide; that is iron (Ill) oxide hydrated and is given the molecular formula FeOOH. With time, ferric hydroxide is mineralized. The principal forms of mineralized ferric iron found in soils are: * amorphous hydrous ferric oxide (Fe203*XH2O), * maghemite ( gamma Fe203), * lepidocrocite (gamma FeOOH), * hematite (alpha Fe203), and * Goethite (alpha FeOOH).
Sewage sludge typically contains between 1 to 2% iron on a dry basis. Iron may enter the sewerage networks through infiltration, surface run offs, scale from rusting iron pipes or from industrial discharges. The chemical forms and make up of iron in sewage sludge are unknown. In general, however, they are found to be un-reactive towards hydrogen sulphide under normal digester operating conditions. S. *
The most commonly used method of removing soluble metal ions for example 5.5.
aluminium, iron, copper and cadmium etc (Al3, Fe3, Cu, Cd, etc.) from solution is to 55...
* precipitate the ions as a metal hydroxide or sulphide. The fact that according to the S.....
* present invention ferric hydroxide of water sludge origin was found to be reactive toward S...
hydrogen sulphide under certain conditions was surprising because ferric hydroxide is *a.
S not soluble, and does not normally react with hydrogen sulphide. This fact is even more
I
surprising when one considers that aluminium hydroxide from water purification processes was found to be un-reactive toward hydrogen suiphide. Aluminium hydroxide with a solubility product constant of 4.6 x i0 is considerably more soluble than ferric hydroxide with a solubility product constant of 4.0 x 1038. The differences in the reactivity between ferric hydroxide and aluminium hydroxide may be due to the ability of ferric iron to undergo a reduction process to form ferrous iron which is soluble.
Table I shows a comparison in the literature of the solubility of ferrous and ferric hydroxide in water at different pH.
Table 1 -Solubility of ferrous and ferric hydroxide in water at different pH PH Maximum concentration of pH Maximum concentration of ________ ferric iron, ppm ________ ferrous iron, ppm 2 60,000 below 6 greater than 90,000,very high 3 60 7 90,000 4 0.05 8 900 above5 0 9 9 The transformation of iron from the ferric form to ferrous form is only possible under a reduced or anaerobic condition and is strongly influenced by the solution pH. Since mineralized ferric iron seems incapable of reacting with hydrogen suiphide, it can be assumed that the kinetics of the ferric / ferrous transformation for the mineralized fernc iron is not favourable. The present inventor believes, although not wishing to be bound :. by any particular theory, that ferric hydroxide and hydrogen suiphide undergo a series of chemical reactions which ultimately result in the formation of pyrrhotite (FeS). The I...
reactions may be described as follows: * *
S * *
Under reduced conditions *SSS Fe34 + e 4 Fe2 Equation (1) 5..
Fe (OH)2 + H2S 3 FeS + 2H20 Equation (2) pyrrhotite Another important factor affecting the formation of pyrrhotite is the solubility of hydrogen suiphide in water. Hydrogen sulphide is only slightly soluble in acidic water, but in alkaline solutions (high pH), the solubility is dramatically increased. Thus it should be clear that the formation of pyrrhotite is limited to a pH range in the region of 5.5 to 9.0 The kinetics of pyrrhotite formation is therefore most favourable in the pH range in the region of 7 to 8. It should be noted that the formation of pyrite (FeS2) under the same condition may be possible also.
Since the formation of pyrrhotite is virtually irreversible, the final concentration of hydrogen sulphide in the treated biogas can reach an extremely low level. The actual hydrogen sulphide removal efficiency would be dictated by the initial concentration of the ferric hydroxide in the reactor and the hydrogen sulphide concentration in the biogas and the contact time between the ferrous form of the iron and the hydrogen sulphide.
For the in situ removal of hydrogen sulphide from a biogas during the digestion process of sewage sludge, the ferric hydroxide is conveniently dispersed in the sewage sludge.
The transformation of iron from the ferric form to ferrous form takes place naturally in the digester which acts as a reactor and provides the anaerobic conditions. The nascent :.:: hydrogen sulphide reacts with the iron as it rises to the gas space at the top of the IS..
digester. The contact time between the hydrogen suiphide and the iron is therefore only
S S....
* a matter of a few seconds. For improved suiphide removal efficiency the contact time * may be extended by re-injecting the gas in the said gas space back into the sludge in the *SS.
digester. Alternatively, the biogas containing hydrogen sulphide may be contacted with IS.
the ferric hydroxide suspension in a separate reactor, as a form of pre-treatment before its utilisation.
In order to specify the quality of the gas supply with respect to the hydrogen suiphide content, it is important to be aware of the requirements laid down by gas engine manufacturers and the emission standards set by industry regulators. Currently most gas engines are designed to tolerate hydrogen sulphide level up to 500ppm, but to achieve (local) environmental emission standards the levels are often not allowed to exceed 1 5Oppm. These requirements may be even more stringent in the future.
Once a target hydrogen sulphide level is set, the level may be monitored and controlled by any conventional feedback control loops using appropriate instrumentation in conjunction with the proper fernc hydroxide storage and dosing equipment. This arrangement may however be very costly to install and may not be compatible with the operation of a sewage treatment works.
In contrast, in line with the present invention, it has been found that the hydrogen sulphide in the gas may be conveniently maintained below a set level by a method as to be described in the following paragraph. Such a method is both practical and simple to implement on a large scale without the need for sophisticated instrumentation and is therefore may be provided at a much reduced cost. S.
:..::. According to equations (1) and (2) above, one mole of ferric hydroxide is required to S...
remove one mole of hydrogen sulphide from the gas to be treated. On a mass basis, * : 55.8g of ferric hydroxide expressed as iron is required to remove 34g of hydrogen * **..
* sulphide from the gas to be treated or, 1.64 kg iron per kg of hydrogen suiphide (H2S). It * S..
* should be noted that, if the reactions resulted in the formation of pyrite (FeS2) instead of **.
S
I
of pyrrhotite, the requirement for ferric hydroxide would be 0.82kg iron per kg of hydrogen suiphide (H2S).
In order to maintain the hydrogen suiphide below a set level an operator has to ensure that the available quantity of iron in the reactor on any particular day must exceed the amount required for hydrogen suiphide removal on a daily basis. This relationship may be expressed as: VRCFe> pKVG (C0 C,) Equation (3) Where VR is the reactor volume CFe is the ferric hydroxide concentration in the reactor expressed as iron.
V is the daily gas volume to be treated.
C0 is the hydrogen suiphide concentration in the gas before treatment.
C1 is the hydrogen suiphide concentration in the gas after treatment.
p is the biogas density (kg/rn3).
K is the iron: sulphide mass ratio (0.82 -1.64) As mentioned previously, there may be many forms of iron in the sewage sludge and there are no practical means to discriminate them, therefore the value CFe must be S. estimated from a known amount of ferric hydroxide fed to the reactor and the predicted S S....
* consumption rate by the hydrogen sulphide removal process. Furthermore, where the *.***. a *
reactor is a continuous flow stirred tank reactor, a certain amount of the un-reacted ferric *5** hydroxide will also be washed out with the flow. The value CFe at any point in time may *S.
therefore be approximated as follows: VRCFe = VRCFeO K E p VG(CSO -C81) -E QCFeA t Equation (4) Where HRT is the reactor hydraulic retention time 1) t is the elapsed time since the ferric hydroxide was added to the reactor.
2) CFeO is the value CFe at t0.
3) K Z p VG (C80 C81) is the summation of amount of iron consumed by the hydrogen sulphide reaction over period t, and 4) QCFe i t is the summation of amount of iron washed out of the reactor over period t.
For a better understanding of the present invention and to show more clearly how it may be carried into effect, the invention will now be described by way of the following examples shown below.
EXAMPLE 1
A water purification plant used 2.3 tonnes of Fe2(S04)3 per day to treat 49,170 m3/d of river water and produces 4,620 m3/d of sludge which had 0.43 gIL dry solids content.
After polymer treatment and settlement 68m3/d of a thickened sludge was recovered.
* * The thickened sludge had the following analysis (Table 2). S... * * *..S
Table 2 -Analysis of the ferric hydroxide recovered from a water purification process *.SS*.
* . _________________________ Determinant Value Units * S Dry solids (DS) 2.93 % Volatile solids 55 % Sulphur content 7.800 mg/kg OS Aluminium content 3.5 g Al/kg DS Iron content 293 g Fe/kg DS
I
EXAMPLE 2
The thickened sludge from example 1 was further treated in a filter press to make a ferric hydroxide cake. The cake was found to have dry solid content 15% w/w.
E)kAMPLE 3 Sewage sludge was fermented in two separate reactors under anaerobic conditions at 41.5 °C. Each reactor contained I OL of sewage sludge. The reactors were identical in all respects except that reactor A contained 1 3.5g of ferric hydroxide expressed as iron.
The ferric hydroxide was in the form of a cake that was recovered from a water treatment works as described in Example 2. The results from the tests were as shown by Tables 3 and 4. The composition of biogas from both reactors was approximately 20% methane and 80% carbon dioxide.
Table 3 -Hydrogen suiphide in biogas during the fermentation of sewage sludge with ferric hydroxide treatment (reactor A).
Run Time H Ammonia m Il' Gas production H2S level (Days) p g / (L) (ppm) 0 5.87 680 0 0 1 6.01 860 3.630 50 2 6.32 910 6.138 50 3 6.61 1,330 7.194 50 4 6.84 1,370 7.194 50 6.74 1,530 7.326 50 6 6.92 1,510 7.326 50 * * ______________ _____________ **** Table 4-Hydrogen sulphide in biogas during the fermentation of sewage sludge without ferric hydroxide treatment (reactor B).
*:. Run Time H Ammonia Gas production H2S level * (Days) p (mg/I) (L) (ppm) 0 5.87 680 0 1 5.32 840 1.235 2,000 2 5.33 1,300 3.380 2,000 3 5.45 1,096 4.485 2,000 4 5.53 1,100 4.940 2,000 5.45 1,230 6.240 2,000 6 5.51 1,230 6.565 2,000
EXAMPLE 4
A sewage sludge digester in the form of a stirred tank reactor with a working volume of 2500 m3 was operated at 35 °C under anaerobic conditions for a number of days (period A) as follows: Parameters Units Values VR m3 2500 Throughput rate m3lday 150 HRT days 16.6 V m3/day 3,000 C0 (H2S concentration) Part per million by weight (ppm) 1.100 Biogas methane % 65 Biogas CO2 % 35 Digester pH pH 7.5 During the second period (period B with 28 days) 4.28 m3 of the ferric hydroxide from Example 1 (Table 2) was added daily to the digester feed. The concentration of ferric hydroxide expressed as iron in the feed was estimated to be 246g/m3. During period B the hydrogen suiphide in the biogas was found to be approximately 20ppm, a reduction of 98.2% from the previous level (during period A). The amount of hydrogen sulphide removed was estimated to be 3.3kg/d. The amount of iron consumed by the hydrogen sulphide according to equation (2) above was 5.4kg/d. The steady state concentration of ferric hydroxide expressed as iron in the digester was therefore 209g/m3. S...
During a further period (period C) no ferric hydroxide was added to the digester feed and the concentration of the ferric hydroxide (CFe) in the reactor was allowed to decline due * to natural displacement by the digester feed and consumption by the hydrogen suiphide. *.. *
The concentration of the ferric hydroxide (CFe) in the reactor for period C was estimated using equation (4) with a K value of 1.0. The operating parameters of the digester during period C were as follows: ElaDsed time t Q4t (days) (ppm) kg H2S removed Estimated (g/m3) kg iron washout - 0 20 3.24 209.00 27.17 2 30 9.68 185.31 76.85 4 20 16.16 164.03 120.84 6 20 22.64 144.89 159.72 8 25 29.10 127.69 194.01 20 35.55 112.24 224.17 14 20 48.51 85.86 273.74 18 20 61.43 64.57 311.28 22 26 74.34 47. 37 339.11 26 26 87.20 33.50 359.12 50 99.92 22.33 372.81 34 80 112.26 13.44 381.45 38 185 123.59 6.56 386.12 44 400 135.44 0.55 387.87 The above results show that during the first 26 days of period C the hydrogen sulphide level in the biogas remained very low. Thereafter the hydrogen suiphide level in the biogas rose rapidly corresponding to an accelerated rate of decline in the calculated concentration of ferric hydroxide (CFe) in the reactor. The results also show that a concentration of ferric hydroxide (CFe) as iron of at least 22g/m3 in the reactor must be maintained in order to keep the hydrogen suiphide level in the biogas below 50ppm.
It will be appreciated that many modifications and enhancements may be made to the S...
basic treatment process outlined herein. For instance, methods for introducing the ferric hydroxide into the reactor may be varied. The biogas may be recirculated through the .5 reactor. The biogas may be treated in a series of reactors some of which may not be generating gases at all. Other possible modifications or applications will be readily apparent to the appropriately skilled person.
References United States Patent 4,218,342 (Thompson, 1980) United States Patent 4,532,118 (Tajiri, et al., 1985) United States Patent 5,286,389 (Hardison, 1994) United States Patent 5,989,513 (Rai, 1999) * * * *** *** 0 * * **.* * S..... * S
S..... * . *..S S * S SS *
S S.. p
Claims (25)
1. A method suitable for the removal of hydrogen suiphide from a gas, the method comprising the steps of (I) contacting the gas with ferric hydroxide in water within a reactor under anaerobic conditions at a suitable pH; and (ii) maintaining the femc hydroxide concentration in said reactor at a pre-determined value.
2. A method according to claim 1, wherein the gas is a biogas.
3. A method according to claims 1 or 2 wherein the femc hydroxide is contacted with the gas in situ.
4. A method according to any of claims 1, 2 or 3, wherein the pH is maintained in a range of between 5.5 and 9.0.
5. A method according to any one of the preceding claims wherein the pH is in a range of between 6.0 and 8.0. * *
6. A method according to any one of the preceding claims wherein the pH is in a **** range of between
7.0 and 8.0.
****** * I * I.....
* 7. A method according to any one of the preceding claims wherein the minimum **..
: ferric hydroxide concentration in the reactor is at least 5g/m3 expressed as the *I.
concentration of iron.
8. A method according to any one of preceding claims 1 to 6 wherein the minimum ferric hydroxide concentration in the reactor is at least 20g1m3 expressed as the concentration of iron.
9. A method according to any one of the prebeding claims wherein the maximum ferric hydroxide concentration in the reactor is at least 500g/m3 expressed as the concentration of iron.
10. A method according to any one of preceding claims I to 8 wherein the maximum ferric hydroxide concentration in the reactor is at least I,000g/m3 expressed as the concentration of iron.
11. A method according to claims 11 wherein the femc hydroxide concentration in the reactor is maintained at a pre-determined value by feeding the reactor with ferric hydroxide at least once every 60 days, preferably at least once every 15 days.
12. A method according to any one of the preceding claims wherein the ferric hydroxide concentration in the reactor is maintained at a pre-determined value by feeding the reactor with ferric hydroxide continuously. S...
13. A method according to any of claims 1 to 12 wherein the ferric hydroxide is * derived from ferric chloride or ferric sulphate.
***... * * S...
14. A method according to any of claims 1 to 13 wherein the gas is generated during S..
the digestion process of sewage sludge.
15. A method according to any of claims 1 to 14 wherein the gas is generated in a water or waste water treatment process.
16. A method according to any of the preceding claims wherein the fernc hydroxide is recovered from a water treatment process and is recoverable.
17. A composition suitable for the removal of hydrogen sulphide from a gas, wherein the composition comprises: a solution of ferric hydroxide in water wherein the solution comprises at least 8% ferric hydroxide expressed as iron on a dry basis; and a minimum of 0.5% solids on weight/volume basis.
18. A composition according to claims 17 wherein the solution comprises at least 15% ferric hydroxide expressed as iron on a dry basis.
19. A composition according to claims 17 wherein the solution comprises at least 20% ferric hydroxide expressed as iron on a dry basis.
:.
20. A composition according to claims 17, 18 or 19 wherein the solution comprises a :..::: minimum of 2% solids on weight/volume basis. S...
S
S.....
*
21. Use of a composition according to any of claims 17 to 20 for the removal of *SSS..
* hydrogen sulphide from a gas. S... S S* *. S
S S..
S
S
22. Use of a composition according to claim 21 wherein the gas is a biogas and the biogas is generated during the digestion process of sewage sludge.
23. Use of a composition according to claim 21 wherein the ferric hydroxide is derived from ferric chloride and/or ferric sulphate.
24. Use of a composition according to claim 21 wherein the ferric hydroxide is recoverable.
25. Use of a composition according to claim 21 wherein the ferric hydroxide is denved from ferric chloride or fernc sulphate and wherein the composition is applied in a water or waste water treatment process. * * * *** **** * S
S
*.**** * *
S
***S** * S I.,. * * S S. S *
S
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|---|---|---|---|
| GB0721912A GB2454490A (en) | 2007-11-08 | 2007-11-08 | Method and composition for removal of hydrogen sulphide from gas |
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| GB0721912A GB2454490A (en) | 2007-11-08 | 2007-11-08 | Method and composition for removal of hydrogen sulphide from gas |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3009686A1 (en) * | 2013-08-19 | 2015-02-20 | Ovive | PROCESS FOR REMOVING HYDROGEN SULFIDE FROM A NON-HAZARDOUS WASTE STORAGE FACILITY |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54100975A (en) * | 1978-01-27 | 1979-08-09 | Shinagawa Furnace | Selective absorption removal method of hydrogen sulfide in gas |
| SU1065029A1 (en) * | 1982-03-10 | 1984-01-07 | Институт нефтехимического синтеза им.А.В.Топчиева | Method of cleaning gases from hydrogen sulfide |
| DD226552A1 (en) * | 1984-09-21 | 1985-08-28 | Dresden Komplette Chemieanlag | PROCESS FOR OBTAINING SULFUR-HYDROGEN BIOGAS |
| US5004588A (en) * | 1988-01-15 | 1991-04-02 | Chevron Research & Technology Company | Process for removal of hydrogen sulfide from gaseous stream |
| DE4104873A1 (en) * | 1991-02-18 | 1992-08-20 | Forsch Aufbereitung | Gas purifier moulding compsn. prodn. for dry removal of hydrogen sulphide - comprises mill drying, classifying and granulating ferric hydroxide slurry from water works |
| FR2675057A1 (en) * | 1991-03-22 | 1992-10-16 | Joassin Luc | Process and reactant for in-situ desulphurisation of biogas and for the elimination of corrosion and nauseating odour problems in anaerobic digesters and in any other mixtures or plants producing them |
| US5976373A (en) * | 1994-07-01 | 1999-11-02 | International Fuel Cells, Llc | Removal of hydrogen sulfide from anaerobic digester gas |
-
2007
- 2007-11-08 GB GB0721912A patent/GB2454490A/en not_active Withdrawn
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54100975A (en) * | 1978-01-27 | 1979-08-09 | Shinagawa Furnace | Selective absorption removal method of hydrogen sulfide in gas |
| SU1065029A1 (en) * | 1982-03-10 | 1984-01-07 | Институт нефтехимического синтеза им.А.В.Топчиева | Method of cleaning gases from hydrogen sulfide |
| DD226552A1 (en) * | 1984-09-21 | 1985-08-28 | Dresden Komplette Chemieanlag | PROCESS FOR OBTAINING SULFUR-HYDROGEN BIOGAS |
| US5004588A (en) * | 1988-01-15 | 1991-04-02 | Chevron Research & Technology Company | Process for removal of hydrogen sulfide from gaseous stream |
| DE4104873A1 (en) * | 1991-02-18 | 1992-08-20 | Forsch Aufbereitung | Gas purifier moulding compsn. prodn. for dry removal of hydrogen sulphide - comprises mill drying, classifying and granulating ferric hydroxide slurry from water works |
| FR2675057A1 (en) * | 1991-03-22 | 1992-10-16 | Joassin Luc | Process and reactant for in-situ desulphurisation of biogas and for the elimination of corrosion and nauseating odour problems in anaerobic digesters and in any other mixtures or plants producing them |
| US5976373A (en) * | 1994-07-01 | 1999-11-02 | International Fuel Cells, Llc | Removal of hydrogen sulfide from anaerobic digester gas |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3009686A1 (en) * | 2013-08-19 | 2015-02-20 | Ovive | PROCESS FOR REMOVING HYDROGEN SULFIDE FROM A NON-HAZARDOUS WASTE STORAGE FACILITY |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0721912D0 (en) | 2007-12-19 |
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