sulfur excreting bacterium - innovationcluster.ca · biotechnology i.e. we employ the processes as...

Biorecovery

Sulfur Excreting Bacterium

Dr.ir. Jan Weijma

Biorecovery

Dr.ir. Annemiek ter Heijne

Prof.dr.ir. AlbertJ.H. Janssen

Dr. Renata D. van der Weijden

Dr.ir. David Strik

Environmental problems Societies are highly dependent on access to mineral and energy resources. At this moment the world depends on fossil reserves of both minerals and energy. For the transition to a more sustainable world it is necessary to change from fossil sources to renewable sources. For minerals, recovery from many residual streams of industry and cities can be a new source. Energy can be recovered from residual streams from cities and agriculture. Finally, new energy conversion technologies based on the sun (biomass, direct sun conversion, fresh water flows) can be developed. By developing new technologies to recover energy and minerals from waste, also new methods can be found to clean up the waste streams from existing processes for energy and mineral extraction from fossil sources. These new technologies enable removal of sulphur, metals and nitrogen, or preventing their emissions from water and gas streams. These technologies will have a positive influence on many environmental problems, like acid rain, climate change, and cadmium pollution of soils. Our solutions The biorecovery group seeks to solve these environmental problems by using biobased technologies to recover energy and inorganic compounds from residual streams. Innovative research is on-going in the following areas: 1) Production of electrical energy, fuels and sustainable heat from residual biomass. This type of biomass is left over after extraction of valuable (food) ingredients from agricultural products. The use of residual biomass enhances the economic and social potential of our processes. We use natural

biotechnology i.e. we employ the processes as they occur in nature. 2) Application of the biological sulphur-cycle in water and gas treatment.

3) Recovery and removal of heavy metals from industrial wastewater and/or groundwater.

4) Biological modification of (waste) materials to reduce the environmental impact or improve the efficiency of industrial processing.

Our approach

Central in our approach is the development and operation of bioreactors that enable the selection of the right organism for the desired conversion. The research is based on lab-scale systems where the selection of natural micro-organisms takes place and can be studied and steered. Next to this practical research models are needed to describe and further develop these processes

The research has a multidisciplinary character, including microbiology, analytical and colloid chemistry, geology, biophysics, process technology, electrochemistry, and automation.

Development of innovative processes for the recovery of inorganic minerals, organic fules/chemicals and the production of renewable energy.

Development of more sustainable industrial production processes, in co-operation with end-users and technology providers.

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

Ralph Lindeboom

Utrecht University, Innovation management (2006)

Wageningen University, Environmental Technology (2008)

Travelling, percussion, martial arts

[email protected]

0317-483227

Autogenerative High Pressure Digestion

Researcher

Ralph Lindeboom

Supervisor

Dr. ir. Jan Weijma

Promotor

Prof. dr. ir. Jules van Lier

Dec 2008–2012

Motivation

Conventional anaerobic digestion is used to produce biogas (~65% CH4, ~30% CO2) from organic waste. leaving a waste sludge, which might be used as fertilizer. In the concept of Autogenerative High Pressure Digestion (AHPD), the methanogenic biomass builds up the pressure inside the reactor up to values of 20 bar. Because the solubility of CO2 increases more, relative to CH4 at higher pressure, the produced biogas in AHPD is of high quality (>90% CH4). This pressurized, high-quality biogas can be directly injected in a local natural gas distribution net. Moreover, the pressure might be used to drive membranes or pumps needed in the process. Acidification of the aqueous reactor phase by CO2 is prevented by CO2 immobilization with silicate minerals. In this way, the process delivers biogas which is ready for distribution, but also clean water and sludge with a possible use as fertilizer. We cooperate with Delft University and the company Bareau in this project.

Technological challenge

The technological challenge is to show that the overall AHPD concept works. This requires research on the following aspects: 1) Anaerobic digestion in a pressurized reactor in which production of gaseous end products will build up to a pressure of 10-30 bar inside the system. With acetate as model substrate, we showed that a pressure of at least 20 bar is possible. AHPD with more complex substrates will also be studied . 2) Modeling of the AHPD-process to quantify the effect of increasing pressure on solubility of CH4 and CO2, and its effect on pH. A first mathematical

model has been made which will be compared with future experimental results. The model is then further refined. 3) Prevention of acidification(due to higher solubility of the weak acid CO2) of the AHPD-process by immobilization of CO2 with silicate minerals. First experiments showed that the biological conditions in the system enhance mineral carbonation of certain silicate mineral rocks, decrease the carbon dioxide content of the gas and buffer the pH, leaving carbonate rock as an end-product. The rate and efficiency of CO2 immobilization in various mineral rocks under AHPD conditions is further investigated. 4) Effect on microbiological population Due to increased concentrations of CO2, CH4 and other gaseous intermediates (H2S, NH3 and H2) in the system, the Gibbs free energy of the involved conversions is altered. This indicates that different microbial degradation pathways might become possible. Furthermore, pressure tolerance of different micro-organisms involved in anaerobic digestion varies significantly. We are co-operating closely with the Laboratory of Microbiology to investigate this further.

Simplified Mineral carbonation reaction mechanism: (1) CO2 (g) + H2O (l) 2 H

+ (aq) + CO3

2- (aq)

(2) CaSiO3 (s) + 2 H+ (aq) Ca

2+ (aq) + SiO2 (s) + H2O (l)

(3) Ca2+

(aq) + CO32- (aq) CaCO3 (s)

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

Jan Klok

Wageningen University, Bioprocess technology (2009)

Cycling, playing piano

[email protected]

0317-484993

Shell Global SolutionsShell Global Solutions

Full scale dynamics of biological sulfide oxidation at halo alkaline conditions

Researcher

Jan Klok

Supervisor

Dr. ir. K.J. Keesman

Promotor

Prof. dr. ir. A.J.H. Janssen

June 2009 - 2013

Motivation

Biological treatment of sulfidic could be a sustainable alternative for gas desulfurization. In the biotechnology process, dissolved sulfide (HS-) is converted to elemental sulfur. In the process, the following overall-reactions will take place: 1. 2HS- + O2 2 So + 2 OH- 2. 2HS- + 4O2 2SO4

2- + 2 H+

The sulfide is biologically oxidized by halotolerant-alkaphilic bacteria to elemental sulfur under oxygen-limiting conditions (1) whereas sulfate is formed at excess amounts of oxygen (2). In addition, non biological sulphide oxidation occur merely leading to the formation of thiosulphate: 3. 2 HS- + 2 O2 S2O3

2- + H2O Thiosulfate and sulfate formation will increase the process costs significantly. While sulfur formation is highly depending on the oxygen conditions, a systematical approach into process optimization is essential. Hence, analytical models and controllers need to be developed to predict and control full scale gas-lift reactors. By the experimentally determination of system responses, mathematical models can be developed.


Chemical sulphide oxidation is enhanced at increasing sulphide concentrations the bacteria inhibited at these conditions. This means that mixing significantly affects the overall system

performance. Mixing is achieved by injection of air, which also serves to introduce oxygen. Due to this dual function a direct coupling exists between fluid mixing and reaction selectivity. Moreover, sulphide and oxygen gradients over the height of the reactor column will play a role in the overall reactor performance. Due to the complexity of these systems, computational fluid dynamics (CFD) simulations are needed to study the dominating biological and auto-catalysed non-biological reactions of sulphide and its reaction products together with the hydrodynamic properties of the bioreactor. A laboratory set-up is assembled for testing of the

CFD models. As it is not realistic to carry out measurements on full scale plants a series of 2 laboratory reactors are used to simulate the equilibrium stages in a full scale reactor system

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

Simon Petrus Wilhelmus Hageman

Wageningen University, Biotechnology (2006)

Basketball, Chess

[email protected]

0317-485098

The influence of process conditions on the precipitation and product properties of biological selenium

Researcher

Ir. Simon P.W. Hageman

Supervisors

Dr. R.D. van der Weijden

Dr. ir. J. Weijma

er

Mrt 2009 - 2013

Motivation

Selenium is scarce and not renewed, as more elements. Selenium is produced from metal mining and is used for glass, food and electronic applications. Besides selenium scarcity, metal mining produces large amount of sludge and waste water containing heavy metals. An alternative selenium source is recovery of selenium from selenate in waste water: for example metallurgical waste water. Selenate is biologically reduced to elemental selenium by various micro-organisms such as sulphate reducing bacteria.

Objective Until now, only tiny non-crystalline selenium particles in the order of microns are biologically produced. The aim of this research is to produce denser and large crystalline selenium crystals for an efficient selenium recovery and an economical process.

Approach

The biological reduction of selenate to selenium takes place in three steps: The first step is the

biological reduction of selenate by the bacteria. The second step is the formation of selenium particles. The third step is the stabilization of the selenium particles during the process conditions in the reactor. Once selenate has been reduced to elemental selenium and bio-precipitated as selenium particles, these have to be removed from the bacteria and the liquid in a separation process. To optimize the recovery of selenium solids, the influence of the (bio)-geochemical factors on the precipitation process and product is researched by varying parameters like T, pH, electron donor and biomass. After, the different selenium particle properties and process kinetics are related to the corresponding reactor conditions.

Photo: fed-batch bioreactors for biological production of selenium

Micro-organism

selenate (aq) selenium (s)

SeO42-

(Co)-Promotors

Prof.dr.ir. C.J.N.Buisman Prof.dr.ir. A.J.M. Stams Prof.dr. P. van Cappellen

non-crystalline selenium (s)

crystalline selenium (s)

Researcher:

Graduated:

E-mail:

Diego Andres Suarez Zuluaga

Process Engineer, EAFIT University, Colombia (2008)

Professional Doctorate in Engineering (Designer in Bioprocess Engineering), TU Delft, The Netherlands (2010)

[email protected]

Anaerobic Methane Oxidation for

Biological Sulphate & Sulphur

Reduction

Researcher

D.A. Suarez Zuluaga

Supervisors

Dr. ir. Jan Weijma

Promotor

Prof. dr. ir. Cees Buisman

2010 - 2014

Waste or process water containing SO4

2-

Air S

Purified Effluent

CH4

CO2

Biomass

Motivation

The main goal of this project is the development of a process with a high rate of biological sulphate and sulphur reduction using methane as electron donating compound. This is a process technology that consumes less chemicals and produces a cleaner effluent than the conventional chemical methods.

Additionally, it produces a valuable reusable product instead of chemical waste streams. Nevertheless, bioreactor technologies based on this conversion have not been developed yet, as there still is a lack of understanding of the mechanism of the conversion and of the involved microbial population.


The research aims to develop a high-rate process for biological sulphate and sulphur reduction with methane. However, this a low-rate process from the techno-economical point of view. The research aims to increase the conversion rate in order to come to a technologically relevant and economically feasible process.

In addition, considering the expected high conversion rates and that the process is still poorly understood, bioreactor research will help to get a

better fundamental understanding of the process, both in terms of the metabolic pathway and the involved microorganisms.

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Paweł Roman

Gdansk University of Technology Department of Chemistry, Applied Chemistry.

Gliding, chemistry, mountain hiking and computers.

[email protected]

+48 505 995 604

Biological H2S and thiols removal from sour gas streams

Researcher

Pawel Roman

Supervisor

Dr. ir. M. F. M. Bijmans

Promotor

Prof. dr. ir. A. J. H. Janssen

Nov 2011 - 2015

Motivation

Protecting the environment by reducing emissions of sulphur compounds into the atmosphere, as well as improving the quality of gas streams are the main reasons to apply methods for gas desulphurisation. Since the early 90's research has been carried out in the area of biotechnological H2S removal from sour gas. This resulted in a family of biological hydrogen sulphide removal processes. The objective of this project is to expand the operating window of this processes to not only remove H2S but also organic sulphur compounds such as methanethiol (CH3SH) as this is often present in natural gas. Biotechnological processes offer many advantages over physico-chemical technologies: • Deep H2S removal; • Operation at ambient conditions (P, T); • Lower operational costs; • No use of chemical chelating agents; • No hazardous bleed streams; • Beneficial use of produced elemental sulphur.


Previous research focused on developing a biological treatment processes for H2S removal from gaseous and liquid stream. The aim of this work is to develop a process in which will be possible remove not only H2S but also methanethiol and higher thiols from gas streams and then the transformation of these compounds to biosulphur. Technological challenge here is to develop a process in which you can easily remove methanethiol from the gas streams which at this moment is the biggest problem. This requires a system where scrubber is integrated with a bioreactor and liquid can be continuously recycled.

Scheme of biotechnological hydrogen sulfide and thiols removal from sour gas streams

Scrubber (left) and bioreactor (right) which will be used for biotechnological gas desulfurization

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

Tim Grootscholten


Playing football, cycling, fishing

[email protected]

0317-483227

Liquid biofuel production from organic residues

Researcher

Tim Grootscholten

Supervisor

Dr. ir. David Strik


(Co-)Promotors


Dr. ir. Bert Hamelers

Oct 2008 - 2012

Motivation

More than 30% of the total used energy in the EU is consumed by the transport sector. To reduce dependency on energy out of fossil fuels and to decrease CO2 emissions, legislation on European and national level stimulates the production of renewable fuels. The advantage of liquid biofuel as renewable fuel is the easy implementation in current infrastructure on short-term. Additionally, Liquid biofuel from organic residues does not compete with food resources.


This research studies a new alternative process for liquid biofuel production, namely biohydrogenation. In the biohydrogenation process, volatile organic acids are biologically reduced to alcohols. Volatile organic acids are common metabolites in the degradation of organic waste-streams and can easily be retrieved in an acidification process. Biomass can always be converted into volatile organic acids, while biomass conversion into sugars is more complex. With the combined processes acidification and biohydrogenation, organic waste can be used as alternative feedstock for liquid biofuel production. The aim of the research is to study the feasibility of combined acidification and biohydrogenation for production of liquid biofuels. Organic residues are acidified for the production of volatile organic acids.

During biohydrogenation, organic acids are converted into liquid biofuels with hydrogen as electron donor (e.g. acetate to ethanol in equation below). The reaction as described in the equation yields a low amount of Gibbs free energy, which is close to the thermodynamical limits of cell conversions.

10

2232

-

3

1.9G

OH OHCHCH H 2 HCOOCH

molekJ

The technological challenge is to apply appropriate conditions in a bioreactor to overcome the thermodynamical limit and to stimulate biohydrogenation. The influence of process variables (as electron donor, pH, temperature, pressure and concentration) is studied to generate an optimal liquid biofuel production based on concentration, rate and selectivity.

Acidification Biohydrogenation

Liquid Biofuel

Organic residue

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Marjolein Helder


Singing, sailing, skiing, hiking

[email protected]

0317-485264

www.plantpower.eu ; www.plant-e.com

Development and characterisation of the flat-plate Plant Microbial Fuel Cell

Researcher

Marjolein Helder

Supervisor

Dr. ir. David Strik


(Co-)Promotors



Nov 2010 - 2012

Motivation

Due to depletion of fossil fuels and increasing worldwide demand for energy, the world is in need of alternative energy sources. These sources should be renewable and abundantly available. Several different sources can be identified, like wind, solar and biomass energy. Even though biomass is abundantly available, discussion has risen on the sustainability of biomass as an energy source due to possible competition with food production for the same arable land. The Plant Microbial Fuel Cell (P-MFC) is a technology that allows us to produce electricity from biomass without harvesting the plant. Therefore it is a technology that produces really sustainable energy.

Technological principle

In a P-MFC solar energy is converted to electricity in a natural way. Plant use sunlight to photosynthesize, thus producing organic compounds. Part of these compounds is used by the plant to grow on and part is passively released or actively excreted via the roots into the soil. In the soil microorganisms break down the organic matter to CO2. In a P-MFC the electrons are taken up by a conductive material which functions as an electrode (anode).

In a second compartment – which is separated from the first one by a membrane –a counter electrode (cathode) is placed where the electrons are used to reduce oxygen. The flow of electrons through a wire enables us to harvest this energy as electricity.


The P-MFC has been proven to work. However, the electrical output of the system is very low and should be increased to make the electricity usable. To increase the electrical output, the complex biological and (electro)chemical processes that are occurring in the system should be characterised and optimised for electricity production. Recent research has shown that one of the limiting factors in the system is transport resistance of ions from the anode, through the membrane, to the cathode. This resistance can be minimised by A: reducing distance between anode and cathode and B: increasing membrane surface area. In the flat-plate design of the P-MFC, anode and cathode are close together and a large membrane area is used. In the coming years I will try to characterise the processes in this system and develop a system that can actually be applied in society as a renewable energy source.

e-

H+

e-

H+

e-e-

H+H+

CV Researcher;

Graduated;

e-mail;

tel;

website;

Doga Arslan

Marmara University, Bioengineering (2008)

[email protected]

0032 14-336982

www.vito.be

Valorization of organic waste streams through fermentation processes

Researcher

Doga Arslan

Supervisor

Dr. ir. David Strik

Dr. ir. Heleen De Wever

Promotor


Oct 2009 - 2013

Motivation

Today, bulk chemicals are typically produced from petroleum resources. As fossil fuel sources are limited, costly and they cause an increase of greenhouse gas emissions, renewable resources are being investigated as an alternative. Various types of biomass resources can be transformed into valuable chemicals. Particularly the use of organic wastes is interesting because they are cheap and abundantly available feedstocks which contain sufficient organic material for easy bioconversion. Through fermentation processes, acids and alcohols can be generated, which can be used as bulk chemicals or energy carriers.


The fermentation process allows conversion of waste materials containing lipids, proteins and carbohydrates. Organic substrates serve both as electron donors and acceptors. The principal fermentation products are volatile fatty acids such as acetic, propionic and butyric acid, and alcohols such as ethanol and butanol. The major goal of this Ph.D. is to gain insight in steering fermentation processes towards a major fermentation product at the highest possible yield. The fermenter system will be regulated with different key operational parameters such as pH, hydraulic retention time, organic loading rate, to generate the desired fermentatation product at high concentrations. Current practical experience with fermentation for the production of chemicals relies on batch treatment, the use of specific bacterial cultures and single substrates in sterile conditions and separate

systems for product recovery. In contrast, this Ph.D. aims to work with continuous fermentation of complex organic materials with mixed cultures. The main problem is that the versatile composition of organic wastes leads to a combination of fermentation products in various amounts. Therefore the technological challenges are: 1. Development of a continuous bioreactor system for complete waste transformation towards a major fermentation product 2. Integration of separation technology into the fermentation process, i.e. in-situ product recovery to increase the yields

PlantPower

Living plants in microbial fuel cells

Researchers

Paula González

Coordinators

Dr.ir. David Strik

2009 - 2012

CV Researcher;

Graduated;

e-mail;

tel;

website;

Paula González Contreras

Pontificia Universidad Católica de Valparaíso, Chile; MSc Biochemistry Engineering (2007), Bioprocess Engineering (2003).

PhD defence Wageningen University on 22-6-12

[email protected]

0317-484993

www.ete.wur.nl/UK/Research

Motivation In 2008, it was discovered at our department that living plants and micro organism can generate green electricity in a biological fuel cell. Now, this is a future emerging technology with potential to provide 20% of Europe’s electricity need. Therefore, the European PlantPower project explores new exiting areas of science & technology. The concept of this renewable energy production is that living plants transform solar energy into organic compounds of which 40% or more can be released into the soil. The released organic compounds can be oxidized by electrochemically active micro organisms that use the anode of a fuel cell as electron acceptor. The electrons are reduced at the cathode with oxygen to water. In this way, day and night electricity can sustainably be produced from biomass without harvesting the plant.


The challenge is to increase the power output of this system with several European research groups. Our research group is focused on maximizing the power output by increasing efficiency and adapting the reactor design and operation. Plant Microbial Fuel Cell

no combustion gasses thus clean

solar energy thus renewable

living biomass & nutrients reuse thus sustainable

5 times more then conventional thus efficient

24 hours per day electricity in-situ

bioenergy without competition to food

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Guus Abercrombie

Dining with friends, Travelling

[email protected]

06-48011128

www.sustainablewinners.nl

Biomass oxidation for sustainable heat production

Researcher

Guus Abercrombie

Supervisor



Apr 2009 - 2012

Motivation

Sustainable energy should be CO2 neutral due to the threat of climate change. It should also be without emissions to the environment. Especially fine dust is a severe environmental problem leading to 2200 deaths per year in the Netherlands alone.

The objective is to develop new energy conversions without burning of biomass. Biological oxidation for sustainable heat production could be completely emission free and can restore the flow of stabile organic compounds back to the soil.

Principle of biomass oxidation Bacteria will break down wood-chips. During the oxidation process heat is produced. This process is similar to hay that goes to brew or storage of compost. Biological fermentation of biomass is a new development, which makes it possible to oxidize biomass by aerobic organism at a temperature of 50 degrees Celsius.

This is a process without burning so no air pollution like the dangerous soot fine dust is produced. Because wood is used, the process is CO2 neutral and because organic compounds are brought back to the soil even CO2 sequestration takes place.

Technological challenge The main technological challenge is the oxidation rate of the wood. The capital cost of the technology will be too high if the wood is oxidation is to low. The objective is to achieve an oxidation rate of 5 Watt/kg wood. We will look at pre treatment of the wood, the particle size, humidity, nutrients and biomass optimization.

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Alexandra Deeke

TU Clausthal, Chemical Engineering, 2009

Volleyball, Reading, Horsebackriding

[email protected]

058-2843190 www.microbialfuelcell.org

Capacitive Bio-Anodes for Microbial Fuel Cells

Researcher

Alexandra Deeke

Supervisor


Dr.ir. Michel Saakes

Promotor

Prof. dr.ir. Cees Buisman

Jun 2009 - 2013

Motivation

With increasing concentration of carbon dioxide in the atmosphere and decreasing fossil fuel reserves new energy sources are necessary. Microbial Fuel Cells (MFC’s) offer the possibility of simultaneous wastewater treatment and energy production. Advantages are the endless availability of the fuel (wastewater) and during MFC electricity production no air pollution is emitted.

Principals of Microbial Fuel Cells

Common MFC systems consist of an anode chamber and a cathode chamber separated by a membrane. The bacteria grow on the anode and convert the organic molecules to carbon dioxide, protons and electrons (fig. 1). The electrons are transferred via an external circuit to the cathode. The protons pass through the membrane to the cathode chamber. In the cathode chamber oxygen is reduced and reacts with the protons and the electrons at the electrode to water.

Technological Challenge The challenge is to develop a reactor system which can overcome the actual problems occurring in MFC systems to derive an MFC for efficient energy production. Current MFC systems need a high conductivity to avoid ohmic losses. To reach a high conductivity two options are mainly used. Either the addition of salt to the wastewater stream or the short distance placement of the electrodes. Neither of these solutions is efficient. The addition of salts before the wastewater treatment in the MFC affords an extra step for the salt removal after the MFC. The close placement of

the electrodes easily leads to clogging of the anodic compartment.

The Fluidized Bed MFC The Fluidized Bed MFC offers a solution to these problems (fig. 2). The Fluidized Bed MFC consists of an anode chamber with floating carbon particles and a cathode chamber. The floating particles in the anode chamber overcome the occurrence of clogging in the MFC. The biofilm will grow on the carbon particles, digest the wastewater and store the electrons inside the particles. The protons are captured close to the outer side of the particles to achieve electro-neutrality. This way the particle can flow through the solution without any ohmic losses. When the particle bounces against the current collector the electrons and the protons are released and the electricity can be collected through the external circuit. The protons pass through the membrane and react at the cathode with the electrons and oxygen to water.

CV Researcher;

Graduated;

e-mail;

tel;

website;

Bruno Bastos Sales

Ceara Federal University (Bsc Physics) Pernambuco Federal University (Msc) - Brazil

[email protected]

058 2843191

www.wetsus.nl

Capacitive Blue Energy for Green Electricity Production

Researcher

Bruno Bastos Sales

Supervisor


Promotor


Apr 2009 - 2013

Motivation

The emission of greenhouse gases became a global concern in recent times. Innovation through scientific discovery is required to achieve a truly sustainable society. To really implement green practices, we must produce energy cleaner and more efficient in all steps: extraction, storage, distribution and use. A frequent overlooked and neglected renewable clean energy is the salinity gradient power (also named Blue Energy). The production of electricity with this method is obtained from the mixing of two water streams with different salt concentrations, e.g. where rivers flow into the sea.

Principle

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-50

-30

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10

30

50

70

0

10

20

30

40

50

60

70

Time (s)

Vo

lta

ge

(m

V)

Po

we

r D

en

sit

y (

mW

/m2

)

A full cycle of charge and discharge of the porous carbon electrodes.

The principle of the modified supercapacitor flow cell (MSFC) is based on flowing salt water through a sandwich of carbon electrodes covered with ion exchange membranes. The concentration gradient yields movement of sodium and chloride ions into the electrodes, charging this way the cell and generating an external current. Afterwards, fresh water flows into the system and the reverse process occurs. The electrodes are discharged and a reverse current is generated.

Technological Challenge The progress of the technology involves the development of materials suitable for this application, to enhance the system performance in terms of power density and energy yield.

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Mieke van Eerten-Jansen

Wageningen University, Food Technology (2008)

Travelling, cooking and dining, sporting

[email protected]

0317-482020

www.ete.wur.nl/UK/Research/

Methane from CO2 with microbial electrolysis

Researcher

Mieke van Eerten-Jansen

Supervisor

Dr. ir. Annemiek ter Heijne


Promotor


2009 - 2013

bacteria

Anode Membrane Cathode

H+

electrons

H2O

O2

CO2

CH4

Motivation

Natural gas has a dominant role in our energy supply. However, most of our natural gas is of fossil origin and therefore it is of utmost importance to have a renewable source of natural gas. Currently, the only renewable alternative to natural gas of fossil origin is to produce natural gas from biomass, e.g. organic waste, and crops. This alternative is of limited use, however, as land, water, and fertilizer, needed to produce the required biomass, are scarce and its use may not compete with food production. Here we propose a new technology that is capable of converting (excess) electricity and CO2 into methane (CH4), the main component of natural gas.


The technology is based on the bio-electrochemical conversion of CO2 into methane in a Microbial Electrolysis Cell (MEC). An MEC (Figure) consists of an anode, where oxidation takes place, and a cathode, where reduction takes place. Our prime focus will be on the microbial cathodic reduction of CO2 to methane, which occurs according to: Cathode: CO2 + 8H+ + 8e- CH4 + 2H2O Besides CO2, also protons and electrons are needed. These protons and electrons are formed in the anode where water is oxidized to oxygen according to: Anode: 4H2O 2O2 + 8H+ + 8- Overall: CO2 + 2H2O CH4 + 2O2 For the overall reaction, combining the cathode and anode half-reactions, to occur additional electrical

energy is needed. The technology can thus be used to convert electrical energy and CO2 to methane, thereby producing renewable gas without depending on biomass. We have proved in our first experiments that it is possible to produce methane from CO2 in a continuous fashion using a biocathode in a MEC. The challenge is to improve this technology, thereby focusing on two key parameters: increasing the volumetric reactor productivity and decreasing the energy needed to produce methane.

Method

Research aims at understanding the key processes occurring in a methane producing MEC, so improved reactor concepts can be designed. The key processes that are investigated are (i) the microbial consortium of the biocathode and its optimal operating conditions, (ii) mass transfer of protons, substrates and products to decrease energy losses, and (iii) the type of electrode and material choice.

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Ir. Fei Liu


Swimming, Jogging, Travelling

[email protected]; [email protected]

058-2843199

www.wetsus.nl

Capacitive Blue Energy: Electricity production from externally-charged membrane capacitive mixing

Researcher

Fei Liu

Supervisor


Dr. Michel Saakes

Promotor


Sept.2010 - 2014

Motivation

Securing the energy supply and combating climate change become universally recognized challenges for the development of the world. Blue Energy, also named Salinity Gradient Energy, has popped up in people’s line of sight. It is inherently clean as the process is based on the mixing of two streams with different salt concentrations (e.g. sea water and river water), without carbon dioxide or any other pollutant emissions. This technology holds a great promise as its worldwide distribution and enormous energy potential, which could meet more than 20% of globe energy demand.

Principle of capacitive mixing

The voltage driven capacitive mixing is based on membrane Donnan potential with addition of a rechargeable power source. The cell is charged in sea water and a certain potential develops (Fig 1A and Fig 2 step A). Then the cell is contacted with river water (Fig 1B and Fig 2 step B), the cell potential increases due to the change of Donnan potential.

After that, a load (light bulb e.g.) is connected in the external circuit to harvest the energy (Fig 1C and Fig 2 step C). The last step comprises the lowering of the voltage as a result of the inlet of sea water (Fig 1D and Fig 2 step D). This technique has a unique advantage that the cell capacitance and Donnan potential can be manipulated in order to store more charge in the activated carbon layer.


Among all Blue Energy techniques, Capacitive Mixing is a novel concept of electricity generation. The main challenge is to get more scientific insight in the capacitive mixing for energy generation and to create innovative designs and technology to improve the energy extraction from the salinity difference.

Key objectives: - Understanding basic physical-chemical processes - Development of materials - System design and operation - Early technology validation

Microbial Electrosynthesis for Chemical Production in a Bioelectrochemical System

Researcher

Suman Bajracharya

Supervisor Dr. ir. Annemiek ter Heijne (WUR)

Dr. Deepak Pant (VITO)

Promotor


2012 - 2016

CV Researcher;

Graduated;

Hobbies;

e-mail;

tel;

website;

Suman Bajracharya


Travelling, sightseeing and sports

[email protected]

www.microbialfuelcell.org

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Motivation

Using biomass (carbohydrates) as the renewable feedstock for chemicals and fuel creates unacceptable competition between food and fuel. Meanwhile, the land, water and fertilizers required to cultivate biomass are scarce. CO2 and low grade waste biomass would be appropriate source of renewable feedstock for chemicals and fuel in the context of fossils resources depletion and threats of global warming & climate change. Bioelectrochemical systems (BESs) offers unique possibilities for clean and efficient production of high-value fuels and chemicals from low-value waste(waters) or even CO2, which is referred to as Microbial Electrosynthesis. Ethanol, produced from acetate, is an attractive renewable fuel as it can be easily integrated into the current energy infrastructure. In addition, it is used as a feedstock for production of other chemicals.


Bio-electrochemical reduction of CO2 and/or acetate at the cathode of a Microbial Electrolysis Cell (MEC) can produce ethanol in a continuous fashion using a pure or mixed bacterial culture as biocatalysts (Fig. 1). An oxidation reaction at the anode of MEC will produce the required protons and electrons for the cathodic reduction. Some additional electrical energy is required to drive the electrons from anode to cathode. At Cathode: CO2 based:

2 HCO3- + 14 H+ + 12 e- → C2H6O + 5 H2O

Acetate based: C2H3O2

- + 5 H+ + 4 e- → C2H6O + 2 H2O

CO2

Bacteria

e-

+ -

e-

e-

Liq

uid G

as

Wastewater

Bioanode

Effluent

CO2 or combustion gas

e-

+

+

+

+

+

A

E

M

+

+

+

+

F

i

l

t

e

r

HCO3-

Biocathode

Ethanol

CO2 + H+

Hydrophobic Extraction

Ethanol

Gas port

COD

Figure 1. Microbial electrosynthesis of ethanol from CO2

The study focuses primarily on the microbial cathodic reduction. Any oxidation reaction, such as oxidation of organics, can be incorporated. The technology can synthesize ethanol from CO2 and/or acetate with small electrical energy input. The project is aimed to prove the new innovative principle and to prove the concept of continuous and energy efficient production using a biocathode in a MEC. The challenge is to develop this technology in combination with product recovery, thereby focusing on optimization of cell components like electrodes and membranes (Fig. 2) to increase the volumetric reactor productivity and decrease the energy consumption.

(a) (b) Figure 2 (a) Graphite foam for bioelectrode (b) Membrane Electrode Assembly (MEA)

sulfur excreting bacterium - innovationcluster.ca · biotechnology i.e. we employ the processes as...

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