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Production of bioenergy and biochemicals from industrial and agricultural wastewater. J.H. Cha. Contents. 1. INTRODUCTION. 2. Biological methane production from organic material in industrial and agricultural wastewater. 3. Biological hydrogen production. 4. Biological electricity production.

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contents
2007

Winter School

For MFCs

Contents

1. INTRODUCTION

2. Biological methane production from organic material in industrial and agricultural wastewater

3. Biological hydrogen production

4. Biological electricity production

5. Biological chemical production

6. Outlook

introduction
2007

Winter School

For MFCs

Introduction
  • Sustainable society
    • reduction of dependency on fossil fuels
    • lowering of the amount of pollution than is generated
  • Wastewater Treatment
    • a paradigm shift; ‘disposing of waste→using waste’
    • Wastewater are potential commodities from which bioenergy and biochemicals may be produced.
    • bio-processing strategies
      • methanogenic anaerobic digestion
      • biological hydrogen production
      • microbial fuel cells
      • fermentation for production of valuable products

Recovery of energy

and valuable materials

- reduce the cost of wastewater treatment

- reduce the dependence on fossil fuels

biological methane production
2007

Winter School

For MFCs

Biological methane production
  • Reaction
    • Methane formation from glucose; C6H12O6↔ CH4 + CO2
  • Methanogenic anaerobic digestion
    • high organic removal rates
    • low energy-input requirement
    • energy production (i.e. methane)
    • low sludge production
  • UASB
    • Upflow Anaerobic Sludge Blanket
    • efficiently retains the complex microbial consortium without the need for immobilization on a carrier material by formation of biological granules with good settling characteristics.
    • Approximately 60% of the thousands of anaerobic full-scale treatment facilities worldwide are now based on the UASB design concept.
biological methane production5
2007

Winter School

For MFCs

Biological methane production
  • AMBR
    • Anaerobic Migrating Blanket Reactor
    • The organic removal rates are higher than those in UASB.
  • ASBR
    • Anaerobic Sequencing Batch Reactor
    • operating in a four-step cycle
      • 1) wastewater is fed into the reactor with settled biomass.
      • 2) wastewater and biomass are mixed intermittently.
      • 3) biomass is settled.
      • 4) effluent is withdrawn from the reactor.
  • The methane has been
    • used as a fuel source for on-site heating
    • used as a fuel source for electricity production.
    • converted to methanol for use in production of biodiesel.
biological methane production7
2007

Winter School

For MFCs

Biological methane production

source: http://www.uasb.org/

  • UASB

Anaerobic sludge granules from a UASB reactor treating effluent from a recycle paper mill (Roermond, The Netherlands).

biological methane production8
2007

Winter School

For MFCs

Biological methane production

source: Angenent et al., Wat. Res. 35(7) pp.1739-1747, 2001

biological hydrogen production
2007

Winter School

For MFCs

Biological hydrogen production
  • Biological hydrogen production
    • It is easy to separate gaseous products from the wastewater.
    • But, successful hydrogen production requires inhibition of hydrogen-using microorganisms
      • homo-acetogens, methanogens
      • propionic acid-producing bacteria; ‘reaction 4’
      • ethanol-producing bacteria; ‘reaction 5’
      • homoacetogens; ‘reaction 8’
    • Inhibition is accomplished by
      • heat-treatment of the inoculum
      • operation at high dilution rates or low pH
    • Hydrogen yield is actually low.
      • theoretically, 12 moles of hydrogen per mole hexose; ‘reaction 1, 8’
      • typically 1-2.5 moles of hydrogen per mole hexose
    • Escape of hydrogen during scale-up
      • due to the high diffusivity of hydrogen
biological hydrogen production10
2007

Winter School

For MFCs

Biological hydrogen production
  • Examples of optimization efforts to maximize hydrogen production
biological electricity production
2007

Winter School

For MFCs

Biological electricity production
  • Microbial Fuel Cells
    • In principle, MFCs are compared with hydrogen fuel cells
    • Several Mechanisms which electrons can be transferred to metals or electrode
      • Geobacter spp.; periplasmic c-type cytochrome proteins
      • Shewanella spp.; soluble quinones (as electron-shuttling compounds)
      • mixed culture; generating higher current than that generated by a pure culture
      • anodophilic bacteria; Geobacteraceae, Desulfuromonaceae, Alteromonadaceae, Enterobacteriaceae, Pasteurellaceae, Clostridiaceae, Aeromonadaceae, and Comamonadaceae
biological electricity production12
2007

Winter School

For MFCs

Biological electricity production
  • Dual-chamber microbial fuel cells
biological electricity production13
2007

Winter School

For MFCs

Biological electricity production
  • Limitation to implementation of MFCs
    • Power density is still relatively low.
    • Technology is only in the laboratory phase.
    • Potential difference(△E) between the electron donor and acceptor
      • max. potential of ~ 1 V
    • However, by linking several MFCs together, the voltage can be increased.
biological electricity production14
2007

Winter School

For MFCs

Biological electricity production
  • To be feasible
    • Improvement in power density is required.
    • Construction and operating costs must be reduced.
      • expensive noble metals in electrodes
      • soluble or electrode-bound electron shuttles
      • aeration at cathode compartments
    • Rates of electron transport to the anode electrode must be improved.
      • selecting a well-adapted anodophilic microbial community
      • optimizing the MFC operating conditions
      • Optimization can be conducted in a systematic fashion only when the mechanisms of electron transfer from microorganism to electrode are better understood.
    • Reactor size can be small enough to make direct bioelectricity production by MFCs economically viable.
biological chemical production
2007

Winter School

For MFCs

Biological chemical production
  • major limitation of bio-energy tech.
    • the relative low cost of the current non-renewable energy source

→ government subsidies, direct local need to save on energy costs

    • It cannot entirely satisfy the energy demand of our society.
  • Therefore, biological chemical production may be more feasible than bio-energy production.
    • conversion to valuable products
  • Strategies to enhance bioconversion
    • improvement of the amount of product formed per reactor volume, per time period
    • process modification (culture immobilization), coupling two separate bioreactors
    • separation and purification

→ the manufacturing cost

→ more selective, more efficient, and shorter separation routes

outlook
2007

Winter School

For MFCs

Outlook
  • Anaerobic digestion
    • mature process, economically viable tech.
    • methane (low value product), catalytic conversion of biogas to syngas
  • Hydrogen fermentation
    • great potential as a pre-treatment step
  • MFC
    • is exciting, but, fundamental understanding of the microbiology and further development of the technology is required.
  • Biochemical production
    • promising process (high-value bio-chemicals might soon be produced from wastewater)
outlook18
2007

Winter School

For MFCs

Outlook
  • Anaerobic digestion
    • mature process, economically viable tech.
    • methane (low value product), catalytic conversion of biogas to syngas
  • Hydrogen fermentation
    • great potential as a pre-treatment step
  • MFC
    • is exciting, but, fundamental understanding of the microbiology and further development of the technology is required.
  • Biochemical production
    • promising process (high-value bio-chemicals might soon be produced from wastewater)
    • optimization (bioreactor design configuration, operating conditions), scale-up
outlook19

Electricity

Phosphorous

Pre-treatment

MFC / SND

L-S Separation

P Recovery

Waste

Water

Water

Melting

PF/MF/RO

Dewatering

Slag

2007

Winter School

For MFCs

Outlook

“The biological oxygen demand in the effluent, which is an indication of how well wastewater is treated, will be too high in all four different bioprocessing strategies, and thus, post-treatment with, for example, activated sludge, is an anticipated requirement. Hence, post-treatment facilities must to be integrated into the design of full-scale bioprocessing operations.”

But, We have an alternative !!