Team:Hong Kong HKUST/Human Practices

• 
• Project
  Overview PE Degradation Alkane Metabolism Alkane Results MFC Design MFC Result Experimental protocol Notebook Parts
• Modelling
  Laccase Alkane Metabolism Alkane and MFC (FBA)
• Human Practices
  Education and Engagement Collaborations Integrated Human Practices
• InterLab
• Medal Requirements
• Safety
• Team
  Team Members Attributions

HUMAN PRACTICE

INTEGRATED HUMAN PRACTICE

1. Environmental pollution of plastics has long been an issue of concern across the globe. Statistics have shown that 8.3 billion metric tons of plastic has been produced since its introduction in the 1950s with most of them still exists in some shape or form up until now. Triggered by the disturbing facts of plastic accumulation, the HKUST hope to solve this issue by degrading some of the most common plastics used and turning these degraded plastic into something useful for everyone.
2. Choosing the substrate - Which plastic to degrade
   • PE used in plastic bags
   • Plastic bag takes up the largest percentage of marine debris and is difficult to be recycled (comparative to PET bottles)
   • Hong Kong plastic shopping bag environmental levy scheme trying to minimize, but the used ones still remains
   • Team takes on the challenge
3. Building up the system – The Microbial Fuel Cell
   • How did we integrate the different parts Originally, we meant to to use different bacteria to secrete laccase and to house the alkane channel and alkane metabolism pathway. But after discussing with Professor Davis Bookhart, we decided to incorporate our entire system into one single Bacterial Artificial Chromosome, so that our system could be more connected instead. The new schematic is as follows.
4. System consolidation – Interviewing Prof. Davis Bookhart
   • - Preliminary ideas presented to Prof. Davis to trigger discussions
   • - Discussions include: sustainability of the system design, what about the extra CO2 generated? → this will be creating another issue (greenhouse gas)while solving one issue (ie, not sequestering the extra carbon from petroleum-based products)
5. Exchanging ideas – Meetup with teams in the environmental track
   • - SUST_ChinaB: project about degrading PET plastic (issues discussed included the ratio of different protein units, how to enhance the attachment of enzyme to the plastic surface)
   • - Team HKJS_S collaboration with Team HKJS_S for the implementation of their nitrogenase module. We hope that the CO2 as the end product of our system will be able to recycle into another food source for Shewanella to generate more electricity. This can also be the good source when Shewanella does not have enough food source from the PE degradation
6. Exploring possible application – A self sustainable charging “Bin”
   • Considered issues such as:
   1. The scale of device → consider the duration in which the plastic will take to degrade (around 80 days according to literature), we need a device to be able to store plastic that will be enough to generate a usable amount of electricity
   2. Location → choose areas where large amount of plastics will be collected without additional need for separation, therefore came with the idea of integrating the device into recycling bins where people will sort out their rubbish when dumping into the bin
   3. Storage energy → slow rate of electricity generation, so the system needs to be able to store energy without lost → for faster output when that energy is needed
7. Integrating our potential users – Market research from info day booth
   • Aimed to find out what are the major concerns when people choose amongst different renewable energy choice
   • Integrate the survey results
8. Finalising our ideas – Final wrap-up with Prof. Davis Bookhart
   • Integrating user experience into the design of our project.
   1. The nitrogenase system still does not solve the CO₂ problem as cells will still undergo cellular respiration. This will only delay the problem. We can trap this CO₂ into a biosphere where plants can grow. This is enabled by building a self-contained biosphere in conjunction with the MFC. A membrane permeable to CO₂ partitions the two, allowing CO₂ to diffuse into the biosphere. There, plants can uptake it as part of photosynthesis. This way will help contain and fix the extra CO₂ produce into a plant that can be later on use as consumer’s food source or just as a lignified plant for later usage. The MFC can generate electricity for a charging station as well as a lamp to enable photosynthesis
   2. The Cu ions that is required for the laccase enzyme can be obtained from Cu that accumulates in our biosphere. It can cross into the MFC chamber through the aforementioned membrane as well.

CO₂ to methane

Carbon dioxides can be converted into methane after undergoing reduction process, in which the molecule uses the energy from the sun / catalyst to break up the CO2 molecule into carbon and oxygen atoms, then combine with hydrogen to form methane and water, as explained on the chemical equation below.

Using irreversible Henri-Michaelis-Menten Kinetics, we try to consolidate an enzyme-catalyzed reaction with a single reaction and and reaction rate equation with Vmax of 0.8 ± 0.07 nmol/min and a Km for CO2 of 23.3 ± 3.7 mM [1].

From this graph, it can be seen that it takes over 3 hours to fully convert 10 nmol of CO2 into methane. It appears to verify that common features of homogeneous catalysts for CO2 reduction to CH4 are low reaction rates (e.g., turnover frequencies) and limited number of turnovers (e.g., turnover number) before inactivation of the catalyst [2].

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