Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/28—Anaerobic digestion processes
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/28—Anaerobic digestion processes
  • C02F3/282—Anaerobic digestion processes using anaerobic sequencing batch reactors
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
  • C02F3/345—Biological treatment of water, waste water, or sewage characterised by the microorganisms used for biological oxidation or reduction of sulfur compounds
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/101—Sulfur compounds
• • 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

Definitions

• This invention relates to a process for treating sulphate-containing effluent.
• sulphate-reducing microorganisms are used to reduce sulphate to sulphide.
• a metabolisable carbon source, sulphate-reducing microorganisms, and sulphate- containing effluent are placed in a reactor where the reduction takes place.
• the sulphide produced through this reduction is precipitated out of solution using a heavy metal and removed in a separation stage.
• Hydrogen sulphide in a gaseous form is also often produced during the reaction step and this collects in a head space above the reactor. It is known practice to purge the headspace using an inert gas. Owing to the make-up of the reaction mixture of the above and other methods, it has hitherto been accepted that the sulphate reduction and methanogenesis cannot take place at the same time.
• a further disadvantage is that the known method does not allow for methanogenesis to occur in the reactor owing to the high level of sulphide, which inhibits methanogenesis, and the efficiency of the method is thus limited.
• a process for treating sulphate-containing effluent in a bioreactor including the steps of:
• the arrangement may be such that methane produced in the process forms bubbles in the effluent and the process may include the further step of removing the sulphide from the effluent by allowing the methane gas bubbles to transpire through the effluent, thus stripping the sulphide from the effluent.
• the methane and stripped sulphide accumulates outside the effluent and the process includes the further step of separating the accumulated sulphide and methane.
• the separated methane may be retranspired through the effluent.
• the process may include the further step of transpiring carbon dioxide through the effluent.
• the carbon dioxide may be added to the methane transpiring through the effluent.
• the carbon dioxide may be sourced from a step downstream of the bioreactor and which produces carbon dioxide.
• the sulphate-containing effluent contains more than 2.5g/l of sulphate on a mass per volume basis.
• the carbon energy source may be selected from the group consisting of primary sewage sludge, dairy waste, molasses, food industry leftovers, coal and acetic acid.
• a bioreaction system for treating sulphate-containing effluent including a bioreactor, the bioreactor containing :
• the sulphate-containing effluent may be obtained from an industrial process, selected from the group including, but not limited to the tanning, mining and paper producing industrial processes.
• the carbon energy source may be selected from the group including, but not limited to primary sewage sludge, dairy waste, molasses, food industry leftovers, coal and acetic acid.
• the culture of sulphate-reducing microorganisms may be obtained from primary sewage sludge.
• the culture of methane-producing microorganisms may be obtained from primary sewage sludge.
• the bioreactor may be an anaerobic reactor.
• the primary sewage sludge may act as a matrix for the culture of sulphate- reducing microorganisms; the culture of methane-producing organisms; the sulphate-containing effluent; and the metabolisable carbon energy source.
• a bioreactor for treating sulphate-containing effluent including: - a bioreaction vessel for containing a reaction mixture including a culture of sulphate-reducing microorganisms, a culture of methane-producing organisms, sulphate-containing effluent, and a metabolisable carbon energy source;
• the bioreaction vessel may be provided with at least one outlet for disposing of treated effluent formed in the bioreactor.
• the bioreaction vessel may be in the form of an anaerobic container.
• the bioreactor may have a separating means for separating the produced sulphide and methane.
• the separated methane may be recirculated via the inlet for providing methane and carbon dioxide.
• a bioreactor according to a preferred embodiment of the invention for the treatment of sulphate-containing effluent F, is generally designated by reference numeral 10.
• the bioreactor 10 comprises an anaerobic bioreaction vessel 12 for containing the sulphate-containing effluent F; an inlet 14 for the sulphate-containing effluent F and a metabolisable carbon energy source E; an inlet 16 for methane and carbon dioxide; an outlet 18 for sulphide and methane; an outlet 20 for treated effluent; and an outlet 22 for waste.
• a separating means 24 is provided in the outlet 18 for separating methane and sulphide.
• the sulphate-reducing organisms and methane-producing organisms are provided by the metabolisable carbon energy source E and are contained in the vessel 12.
• the flow of the sulphate-containing effluent F and metabolisable carbon energy source E which enter the vessel 12 via the inlet 14, is indicated by arrow A.
• Methane and carbon dioxide are pumped into the vessel 12 via inlet 16 as indicated by arrow B.
• the sulphate-reducing organisms reduce the sulphate contained in the effluent F to sulphide and the methane-producing organisms utilise the carbon energy source E to produce gaseous methane.
• the gaseous methane so produced transpires upwardly through the sulphate containing- effluent F and strips gaseous sulphide from the effluent F.
• the methane and the stripped sulphide gather in a headspace 32 above the sulphate-containing effluent F.
• Sulphide and methane flows out of the vessel via outlet 18 as indicated by arrow G.
• the sulphide and methane are separated by the separating means 24 provided in the outlet 18.
• the sulphide is recovered from the gaseous phase via an outlet 30.
• the separated methane is recirculated back into the vessel 12 in a recirculation pipe 28 as indicated by arrow H and re- enters the vessel 12 via inlet 16 as indicated by arrow I.
• the flow of carbon dioxide, provided from a source 26 downstream of the bioreactor 10, is indicated by arrow I.
• the carbon dioxide enters the vessel 12 through inlet 16 and is transpired upwards through the sulphate-containing effluent F.
• the carbon dioxide also strips the gaseous sulphide from the effluent F.
• the process has several advantages over conventional processes. For example, by introducing the metabolisable carbon energy source in an amount in excess of an amount that would be required for the biological reduction of sulphate to sulphide in the effluent, the concomitant occurrence of methanogenesis is achieved.
• a further advantage is that the methane gas produced during methanogenesis strips the sulphide gas produced during sulphate reduction to obtain a relatively more efficient reduction of sulphate.
• the sulphide gas is thus removed from the vessel 12 without inhibiting the further reduction of sulphate to sulphide.

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• Life Sciences & Earth Sciences (AREA)
• Microbiology (AREA)
• Engineering & Computer Science (AREA)
• Biodiversity & Conservation Biology (AREA)
• Hydrology & Water Resources (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Molecular Biology (AREA)
• Health & Medical Sciences (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
• Physical Water Treatments (AREA)
• Apparatus Associated With Microorganisms And Enzymes (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)

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• 2008
  • 2008-10-16 EP EP20080838715 patent/EP2217537A2/de not_active Withdrawn
  • 2008-10-16 WO PCT/IB2008/054247 patent/WO2009050661A2/en not_active Ceased
  • 2008-10-16 AP AP2010005225A patent/AP2926A/xx active

Non-Patent Citations (1)

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