The Nanjing-China team is committed to alleviating global warming through the development of new bioenergy, and then proposes new solutions to the climate crisis. During the whole process of the project, we always start from the perspective of the relationship between society and technology and pay attention to the expectations and suggestions of different parties for our project. Our goal has always been to use synthetic biology techniques to continuously improve MFC and make our efforts a reality. Providing beneficial solutions for human survival is our core value.Therefore, how to build an effective system, how to implement our product design, how to optimize every step of the implementation, and how to confirm that our project is good for the world are all our concerns.
In the process of integrated human practice, we have gradually refined our improvement plan through exchanges and ensured our project beneficial for the world. Through communications with scholars, we have obtained professional guidance and opinions. In the course of the experiment, we got useful help. In the construction and optimization of the product system, inspiration from the enterprise has been obtained. We also conduct targeted research according to the needs of our potential customers.
We always believe that our project can gratifying progress to the development of synthetic biology and the society, and open a new window for the future of mankind. Professionals in different fields provided us with valuable advice from their respective perspectives, allowing us to achieve substantial results. Sincere thanks to them.
Topic Research
In the ecology course, Professor Xu shared with us his research on global warming and human living space. Members of our team are interested in this topic. After the class, we further consulted him about the impact of fossil energy on the global climate. Professor Xu suggested that we read the IPCC report for more information on the climate crisis. Through Professor Xu's sharing and the IPCC report, we are concerned about the impact of the use of fossil energy on the climate crisis and decided to find cleaner and more renewable energy to meet this challenge.
Improve Option Selection
During preliminary research, we learned that current MFCs often exhibit unsatisfactory low power densities. Thus, we interviewed Mr Guo who was an investor and responsible for the screening of electrogenic bacteria in a scientific research project.
He told us that MFC has three main limiting factors: electrodes, device design and strains. And for strains, the sluggish transmembrane and extracellular electron-transfer processes are the biggest flaws. He proposed two improvements: one is to adopt more flexible measuring methods, such as extending the testing time to show the advantages of our products; The other is to find a variety of electrogenic bacteria and Shewanella for lateral comparison, from the material aspect to improve the effect.
At the same time, Mr Guo believes that bioenergy is still promising, with challenges and opportunities. He said that with the increasingly serious energy problem, scientists wanted to find new energy to replace the old energy, coupled with current China's relevant industrial chain has been relatively sound, which gives us broad application prospects. If we can achieve power breakthrough and convenience improvement, so that the product can achieve basic and practical application, such as using our technology to light a small bulb, can gradually carry out social popularization and promotion. Only first can let consumers interested in, let users have experience, can promote the industrialization of products.
Inspired by him, we finally chose the strain as our transformation object. In the whole process of the project, we also paid great attention to the popular science of MFC, to improve the public's interest and awareness of MFC.
The Interview of Prof. Zhang and Lab Visit
When browsing the official website of relevant colleges of our university, we found that the research group of a professor from the School of Chemistry and Chemical Engineering of our university was engaged in the research of MFC (MFC). After we got in touch, the professor had a cordial exchange with us, and we benefited a lot. We list all the aspects of what we learned.
1. Topic Selection:
The professor asked us some key questions: What are the existing problems with MFC? What problem has someone else solved? What problem are we trying to solve? He also advised us that the topic should be novel, scientific, or have economic value. If it is to repeat the experiment of others, it makes no difference to only make general improvements, and the experiments in the literature are difficult to repeat in a short time.
2. Application:
Professor Zhang told us that the earliest MFC was used to decompose organic matter; What is done more is sewage treatment; But not so much for sensors, enzymatic biofuel cells are better.
3. Battery Construction:
He suggested that we don't have to have a membrane. A well-made battery can be single-compartment. For Shewanella, no oxygen electrode is needed to ensure its oxygen-free environment. The cathode is only used to accept electrons, and other materials, such as potassium ferricyanide, can be used.
4. Electrode:
We have learned from Professor Zhang that good electrode material can increase the conductivity and stability of the battery. And generally, we do not use planar electrodes but choose 3D materials (In this part, how to keep the four-dimensional structure of the electrode does not collapse is also a problem.)
As to electrode materials, in addition to Ag, some other metal ions will be used, such as gold, semiconductors, and magnetic materials with good biocompatibility. Generally, people do not use Ag because they think it would kill Shewanella.
5. Electron Transport:
He also reminded us that to achieve high electron transport efficiency, the bacteria should be closely combined with the electrode, and the electrons transmitted indirectly are relatively limited. The difficulty in improving the efficiency of indirect transport lies in that the two pathways of Shewanella are not very clear. (One of the most important aspects of MFC is how to accelerate the rate of electron exchange, which has been studied in his lab for many years.)
6. Strain:
Professor Zhang told us that functionalization on the surface is not an improvement, but direct genetic modification.
There are two examples:
(1) For example, photoactive bacteria can modify photoelectric materials on it for a synergistic effect.
(2) To solve the problem of long battery start-up time, Fe3O4 is modified on the bacteria, and then the use of magnetic electrodes can accelerate the enrichment rate of bacteria (at the same time, Fe3O4 is a nutrient, which has dual functions).
7. Laboratory Visit
Finally, we visited his laboratory and saw the electrochemical workstation (figure1) and the H-shaped two-chamber fuel cell (figure2).
Obtain Guidance from a Corresponding Researchers
When collecting data, we found that the Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, a native institution specializing in bioenergy research, has a profound accumulation in this field. Therefore, we contacted Professor Cong and Dr Chen in his group at the institute to visit.
There, Dr Chen first introduced the development status of the world's and China's bioenergy industry and explained the current frontier research directions. We have learned about emerging bioenergy technologies such as energy plant breeding, biomass fuel production, microbial treatment of carbon-containing exhaust gas, and microalgae carbon sequestration, and had a deeper understanding of the research community and industry. We also learned that MFC are still in their infancy and deserve further research, which encouraged us to move forward with the project.
Next, we interviewed Professor Cong and asked him about some of the problems we encountered in our experiments and modelling. Professor Cong answered our doubts enthusiastically. Knowing that our project may require a long research cycle, he suggested that we create a model before building the full cell, which will help guide our next experiments. He also put forward his insights on setting and adjustment of the parameters of the model. These are practical suggestions for our modelling work.
A Preliminary Discussion on the Implementation Direction
Professor Tian has done some research work in the field of MFCs and is an expert in the field of ecology. So, we hoped he could provide some practical direction for our project.
We communicated with Professor Tian by phone. He reminded us that the main application direction of MFCs is sewage treatment, and the generated electricity can be used for the regulation and information source of the control device. This is the prototype of the product we designed later. We also discussed the application of MFCs in sensors or in vivo batteries. He suggested that we could focus on the research hotspot in medicine – the artificial heart. Patients with heart failure currently have no other treatment other than installing an artificial heart, which requires carrying large batteries with them, which can greatly affect the patient's life quality. If our MFCs can be used as a power source for artificial hearts under the premise of ensuring biosafety, it will be a boon for patients. This is a great inspiration for us, and we are studying the feasibility and subsequent specific application design.
Seeking Advice from the Battery Industry
Consider that when our MFC is applied to sewage treatment, it will continue to generate electricity. So where does the generated electricity flow? Our first thought was to store it with batteries, so we interviewed the CEO and the technical director of a battery material company. This company, which processes and produces anode materials for lithium-ion power batteries, has a lot of knowledge about batteries and the energy sector and gave us a new perspective.
In their opinion, secondary batteries will replace primary batteries in the future, and fuel cells will be a strong competitor to existing lithium-ion batteries. As for MFC, they believe it is developing in a different direction from power batteries. Compared with power batteries, MFC is less powerful, but they can treat sewage and have the advantage of environmental protection and can be used in wetland parks or sewage treatment plants, etc. The electricity generated can be stored and used in park equipment. In their opinion, MFC is different from batteries in that they have a continuous power output and no storage function, so they need to be equipped with storage stations or used by appliances. They also gave us a new perspective here: many retired power batteries could be used for energy storage, which would solve the electricity storage problem of MFC on the one hand, and the reuse of end-of-life power batteries on the other, and play a bigger role on the environmental protection level. In wetland parks, MFC can supply power to streetlights while purifying water, achieving the purpose of environmental protection and energy saving. In sewage treatment plants, a large amount of sewage may generate a lot of electricity, and they propose that this part of electricity can be used for the operation of the sewage treatment plant's equipment, reducing enterprise costs and providing economic benefits.
Following this interview, we surveyed the current status of power battery recycling around the world and concluded that retired power batteries are indeed an excellent downstream device for the power generated by MFC. Here is our research report:
Feedback from Target Users
After completing the initial construction of "power generation-storage", we visited our target users - sewage treatment plants. During the visit, we got to know that they mainly used membrane technology to treat sewage. The MBBR (Moving Bed Biofilm Reactor) method is mainly used in the treatment process, which uses microorganisms in biofilm to break down organic matter in the wastewater; they also use MBR (Membrane Bio-Reactor) as well, which combines the filtration of membrane technology with bioreactor for sewage treatment. The heavy metals in the wastewater are absorbed and enriched by the microorganisms, after which they are sent to a specialized facility for treatment.
After learning about our project, they believe that MFC can be derived for a wide range of application dimensions. For example, it can be applied to sludge treatment in the sewage treatment process. Sludge is a relatively serious problem for sewage treatment plants now, and the current main treatment methods are drying and incineration, which require a lot of energy. If microorganisms can be used to supply electricity while degrading sludge, it will be able to save a lot of costs. In addition, in the process of sewage treatment, it is also possible to use MFC for organic matter decomposition and electricity production.
We learnt that the sewage treatment plant currently treats 120,000 tons of wastewater per day, so the potential electricity to be generated is considerable. The operating cost of the sewage treatment plant is also dominated by electricity consumption, which is mainly used for the operation of equipment. Electricity consumption can account for 30% to 40% of the cost of enterprises in the sewage treatment industry. Therefore, for the sewage treatment industry, our project can firstly assist in sewage treatment, also save costs and bring great economic benefits, while promoting energy conservation and emission reduction, providing significant environmental benefits. The sewage treatment plant also pointed out that they mainly treated domestic sewage, where heavy metal content is low, and the silver ion concentration is low. In contrast, industrial wastewater has a much higher content of heavy metals and we can consider the applications in this area.
Respond to User Needs
Users have put forward needs to us, and we must respond to them to improve our product and make it better suited to the market. To solve the problem of a large amount of sludge generated in the sewage treatment process, we visited Nanjing Lotus Environmental Protection Technology Company. Dr Song received us and gave us a brief introduction and exchange.
This company is committed to improving the efficiency of sewage sludge treatment by using microbial treatment technology. Sludge is a kind of flock-like sludge particle, which is formed by polysaccharide substances produced by microorganisms such as Zoogloea ramigera and mixed with other suspended substances in sewage. It has a strong ability of adsorption and decomposition of organic matter and good settling performance. The sludge problem has always been an important part of sewage treatment. The original treatment methods are generally incineration, landfill and synthetic building materials, which not only increase the cost but also may cause secondary pollution. LOTUS is cleverly based on the front end, inhibiting sludge at the source. They do not rely on the Zoogloea to settle the sewage. Instead, they grow other microorganisms that do not produce polysaccharide substances on a special porous inorganic material. The microorganisms are responsible for adsorption, and the special materials are responsible for settling, to achieve the purpose of sewage treatment together.
We introduced our project to Mr Song Chen and asked for suggestions. The type of sewage also matters, he suggested, if we wanted to combine sewage treatment with microbial batteries. For Shewanella, sewage with high organic content, such as sewage from wineries and food factories, may be more suitable. At the same time, he thought our project can be applied to all kinds of life scenarios. Such as small emergency storage batteries or medical devices such as pacemakers or detectors. We expressed our intention to cooperate with him, hoping to further advance laboratory experiments. Dr Song agreed and hoped that we could give a complete design and optimization plan. We are currently in the process of further optimization.
More Possibilities
When considering the implementation of the project, we noticed that there are many stray cats on campus with collars. So, we thought, what about the energy source and battery life of the collar? Can we use our MFC to power the collar? With these ideas, we found the owner of the collar, Professor Li, an expert on animal behaviour.
Professor Li explained his topic to us in detail and told us that the current collar uses a primary battery, which is indeed facing the problem of insufficient battery life. We introduced him to our project and he showed great interest. Professor Li said that if our battery could last for a month under the condition of controlled volume, it would be of great help to his research. We discussed the application scenarios of MFC in detail and obtained relevant materials after the exchange. We will continue to consider this option and move forward with the manufacture of actual products in the future.