Team:XMU-China/Human Practices
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Integrated
Human
Pratices
HP Overview
XMU-China continues to be line with the concept of solving local issues and assisting the optimization of world's environmental protection this year and focuses on clean energy -- nuclear power, and carries out a number of HP investigation activities based on this. Along with the communication with the engineers of nuclear power plant, professors and other stakeholders, finally this year's project is determined--''SALVAGE''. After completing the preliminary design, we visited a few of nuclear power plant engineers and professors again to evaluate and confirm our project.
Our team has fully realized the importance of HP. An effective interaction between HP and the project design can make the project independent of the laboratory to face society and help it turn to be a project beneficial to the society and make certain contributions to the world. Therefore, the HP part runs through the entire design of our project. The more deeply we dig, the more clearly the meaning of SALVAGE and the responsibility of XMU-China display: using safe synthetic biological means to efficiently solve the key problems in reality, so as to be rewarding to the public and to facilitate the world well.
1. Set the project content – "SALVAGE"
a. Determine the orientation of project
It has been the age of electricity since the second Industrial Revolution. As the technology gathers rapid momentum, global electricity consumption is increasing day by day. From January to August of 2021, China's total social electricity consumption reached 5.4704 billion KWH, with a year-on-year increase of 13.8%. However, traditional thermal power not only consumes non-renewable resources such as coal heavily, but also releases pollutants such as disulfide. Hence, the exploitation of clean energy has become a crucial focus in China and even the world.
In order to accord with the global trend of energy conservation, environmental protection and emission reduction, countries are vigorously accelerating the arrangement of nuclear energy. Nuclear power is a kind of clean energy with enormous predominance such as slighter environmental impact, lower resource consumption, more prodigious supply capacity, and greater development potential. According to the International Atomic Energy Agency, 10-25 countries will be the member of the nuclear power club and the global capacity of installing nuclear power plants will increase at least 40% by 2030. Nuclear power will be the main choice within the international power structure adjustment, and the investment scale of it will also greatly transcend that of conventional power plants in the future. The national strategy of nuclear power has changed from "moderate development" to "positive development". In this context, China's nuclear energy industry will have an unparalleled opportunity to thrive.
This year, XMU-China focuses on coastal areas of China. Here, nuclear power has been utilized maturely as a clean energy in accordance with local conditions. A report caught our eyes -- red tides would cause water temperature rise and make the cooling water systems of nuclear power plants linking to the sea water unable to operate normally. The abnormality of cooling water system operation would lead to the malfunction of nuclear fuel heat release, which seriously threatens the safety of nuclear power plants. Thus, we start the field study based on this information and apply synthetic biology to “salvage” the cooling water system of nuclear power plants so as to retain the safe operation of nuclear power plants.
b. Explore the specific problems in cooling water system
The water source of the cooling water systems at the coastal nuclear energy plants is often the seawater. Hence, the unobstructed current and normal temperature are vital for the error-free running of plants. As further reading of relevant literature and news reports goes, it’s learned that marine organisms have negative impacts on cooling water system, for instance, producing heat resulting in the increase the temperature of cooling water and blocking cooling water system. Furthermore, the blocking would also bring about the reduction of operation efficiency and even the shutdown of nuclear power units, leading to the enhancement of energy consumption and detrimental effect for the operation economy. It has been reported that the drum net of the filtration device of the cooling water system was clogged due to the outbreak of Sargassum in the South Sea of China in 2018, leading to the shutdown of two units. In addition, blockage caused by marine organisms need to deal with, which increases labor costs.
To be concluded, we hope to alleviate even figure out these issues caused by marine organisms with the means of synthetic biology, preventing the acceleration of the temperature cooling water, congestion and contamination of the whole systems.
c. Communicate with the staff to substantiate the necessity of our project
According to the previous investigations, we are aware that the efficiency of the cooling system ties up with the safety of nuclear power plants, and some marine organisms have great adverse impact on the operating efficiency of the cooling system. So, we would like to conduct field visits to nuclear power plants and interview related employees to collecting more concrete and detailed information to check the necessity of solving these problems, which is of great practical significance.
With such an expectation, we contacted the engineers of some nuclear power plants located on the east and south coast of China, Ningde Nuclear Power Plant and Zhangzhou Nuclear Power Plant in Fujian Province, and held several in-depth micro-seminars and obtained much. It’s showed that the organisms in the ocean including algae, shellfishes, and small fishes generate the blockage into the nuclear plant cooling system, and among them, mussels and Phaeocystis globosa serve as the most notorious roles. Chemical killing and multi-layer filter screen are the empirical adoptions to solve this kind of blockage.
Chemical killing uses hypochlorite acid produced by electrolytic seawater. There is a sudden increase in the number of algae during the outbreak period, which is difficult to adjust the concentration of sodium hypochlorite in real time. It turns out to be that the unprocessed algae still wrap the filter reducing the water flow speed.
As for the multi-layer filter, it involves three layers: the first layer is thick grille with large pore size, mainly for stop of large marine waste and organisms; the second filter is fine grid, mainly for rejection of some marine life attachments such as mussels, etc.; the third layer is rotating filter in aperture 3mm, mainly for the interception of the most organisms affecting the operation of nuclear power plant. In addition to the wrapping algae hamper the inflow of water, there are often mussels clinging to the grilles, jamming the current of cooling water as well.
The methods to remove mussels are usually classified into two categories-physical means such as manual cleaning and replacing of grilles, and chemical means applying chemical painting covered on the grilles Notwithstanding, traditional measures not only fix little but also cost much. Besides, the engineers also highlight that the attachment issues of large marine organisms feature long period, high frequency, much interference in equipment, no ideal solution, and complicated maintenance, etc. Consequently, it’s very urgent to find out an effective way.
Thus it could be deduced that blockage matters are far more serious and common than the rising water temperature caused by the red tide in the nuclear power plant. After prudent investigation, we finally keep a close watch on "mussels" and "Phaeocystis globosa", and manage to solve the blockage of mussels and Phaeocystis globosa at the inlets of cooling water systems in the nuclear power plants via safe and socially responsible synthetic biological means.
Nuclear Power Plants
Ningde Nuclear Power Station
Zhangzhou Nuclear Power Plant
Due to the concern of industry security, the following engineers of nuclear power plants would be anonymous and the precise name of nuclear power plants would be veiled.
EAST COAST OF CHINA
Mr. H, Equipment Management Engineer in nuclear power plant A, is responsible for the cooling system functioning.
We inquired Mr. H about the cooling system blockage in the nuclear power plant of which he is in charge. He believes that marine fishes and shrimps are the main obstacles for their cooling system. Luckily, since their cooling system consists of titanium pipes, the biofouling caused by the above marine organisms does not actually pose a substantial threat. As for the attachment of molluscs to the coarse grille which locating at the water inlet, sodium hypochlorite is introduced for disinfection and has reached the expectation roughly. However, he added that the high concentrated sodium hypochlorite they use to prevent fouling organisms can cause pollution to the ocean, so he looks forward to any possible solutions that are safer and more environmentally friendly.
SOUTH COAST OF CHINA
Mr. L, Electrical Engineer in nuclear power plant B.
Mr. Y, Senior Chemical System Engineer in nuclear power plant B.
Mr. D, Corrosion Engineer in nuclear power plant B.
In the interviews to these engineers in the south coast of China, we learned that the external cooling water system of a nuclear power plant consists of several filters, including a coarse grille, various levels of barriers, and an automatic filter, from outside to inside. The pore size is reduced more and more in order to prevent unexpected marine creatures into the circulating sea water. It’s these filters’mission that is mainly stopping the entry of marine objects into the water channel.
The staff often intercept large objects by filters, and sodium hypochlorite is produced by electrolysis of marine water to kill small marine objects. The clogging of inlet filters that has attracted much attention in recent years is mainly caused by small marine creatures, such as shrimps, jellyfishes, algae, mussels, barnacles, oysters and other fouling objects.. The number of algae would sometimes increase suddenly during the outbreak period, and it is difficult to adjust the concentration of sodium hypochlorite in time. As a result, the remainder and the other small organisms will still block the filter and reduce speed of the water flow. Moreover, the need for releasing attachment of large marine objects is also urgent because it has been a long-lasting, commonly occurring, substantially impacting one that lack of ideal countermeasures so far.
SOUTH COAST OF CHINA
Mr. C, chairman of Safety Department and former Equipment Management Engineer in nuclear power plant C.
In order to make it clear that how our functional proteins work and prepare for our hardware design, we consulted the crew about the common size and water flow speed of their external cooling water system.
There are two sea water pumps for the cooling system, each with a flow rate of about 20 m3/s. Speed at the water inlet is relatively slow among the whole system, at about 0. 5 m/s, and then the speed is rising until two times or slightly lower at the inner filter. Therefore, we should make adjustment in different places so that the functional proteins have proper concentration and enough time to function. According to the flow speed and width data of the water inlet and outlet, we can adjust the length and light intensity of the blue light strip of the suicide switch, so that the suicide circuit in the engineered bacteria can be effectively induced, which the engineered bacteria will not be released into the natural water body.
The water inlet
Houses that shelter the water pumps
Coarse grille that waits to be cleaned up by mechanical methods
Mussels are the dominant fouling organisms, which stick firmly as soon as they settle down.
We invited several experts in Ningde Nuclear Power Station to consult the fouling issues encountering during the practical operation of the cooling water system.They are Mr. Hongbo Wang from the Chemical and Environmental Protection Department, Mr. Quanxing Kong and Mr. Wenhuan Yang from the Anti-fouling Department, Mr. Lin (the main speaker) and Mr. Dongsheng Huang from the Equipment Department, and Mr. Jinlong Ye from the Service Department. Some details in design and application were presented by us and the empirical solutions were given by the engineers.
They first introduced an kind of machine from which sodium hypochlorite was produced directly from electrolytic seawater using surplus nuclear power, then the sodium hypochlorite was diluted and then added to the target water through pipes to maintain the chlorine concentration within certain range. The chlorination is quite effective usually so the fine grates and subsequent structures could be free from marine organisms under normal situations, but a small amount of them adhere to the bottom of the grates due to the lower dosing concentration sometimes. In return, the adhesion due to the uneven chlorination could result in more uneven chlorination in the pipes ,which leads to more attachment of marine organisms to the downstream grates.
Furthermore, there are mainly risk warning and interception nets at all levels in response to fouling by marine organisms, but the interception system is not perfect for now and the nuclear power plant is planning to upgrade it. Emergency salvage is mainly carried out by hiring fishermen adjacent during outbreaks of marine life, but the framework for temporary recruitment and lasting emergency plan system to figure the outbreak out is not well developed yet.
Zhangzhou Nuclear Power Plant was once the largest power producer in China, with advanced facilities, high automation, and environmental measures ranking top in China. Tongchang Gan is the engineer in charge of the conventional island of Zhangzhou Nuclear Power Plant and is responsible for the technical management of the turbines for circulating water. Communicating with Mr. Gan, we gained a preliminary understanding of the current status and challenge of circulating cooling water systems in the nuclear power industry. Due to the huge usage of cooling water for condensers, the coastal nuclear power plants in China mainly use seawater as cooling water according to the principle of proximity.
Using seawater as cooling water could trigger many issues. For example, sea creatures may clog or stain the heat exchanging tubes of the condensers, which would have vital influences on the operating efficiency and the energy consumption of the power units, and worse than that, would cause deficiency of cooling water endangering the operating safety. Additionally, these problems also increase the cost of nuclear power plants, told by the corresponding engineers--blocking or staining requires frequent cleaning, which increases labor cost. According to experience, there are various kinds of disaster-causing substances affecting the operation of the units, such as marine garbage, water plants, algae, jellyfishes, fishes and shrimps with floating capacity, etc. For the cooling water system behind the coarse grille in the pump room, the marine organisms negative to the cooling water are mainly algae and shellfishes, such as Sargassum, Phaeocystis globosa, mussels and so on. An engineer cited an example for us to let we know more about the hazard of the marine organisms to the plants: there were two power units shutting down at Hainan Nuclear Power Plant in 2018 due to an outbreak of Sargassum in the South China Sea, which blocked the drum network of the filters of the water intake system.
We also learned that the methods present dealing with marine organisms of nuclear power plants are mainly physical filtration and chemical disinfection. Physical filtration is to set up multiple interception devices before the circulating water pumps to salvage or filter out the sea creatures or trash larger than 3mm. Chemical disinfection is to use hypochlorous acid to inhibit or kill the larvae or spores of marine organisms like algae and hamper their attachment and growth in the pipes of the coolers and the flow channels after the filtering device. The common way for the nuclear power industry to obtain hypochlorous acid is to use the circulating water treatment system (WCT) to produce a maximum concentration of about 2000 mg/L of effective chlorine by electrolysis of seawater. There are two ways of chemical disinfection, continuous dosing and impulse dosing. By the above means, the condensers and heat exchanging tubes could perform well in most of the time to ensure the safe operation of the power units. After that we fully learned that the marine organisms indeed make big troubles for the nuclear power industry of China, which is also proved that our project is viable and scientific. We also have rudimentary comprehensions of the existing means of eliminating marine organisms in nuclear power industry, which will facilitate the forthcoming improvement and discussion of the project much.
2. Enact the scheme
a. List out the synthetic biological measures could be
It’s more clear that it of great urgency and significance to figure the blockage at the inlets of the plant cooling water systems out after the interviews of the engineers. At the same time, the drawback of existing physical and chemical means has made synthetic biological means get more attention.
In order to solve the issue from the root, and prevent repeating blockage, we would focus on the following three items. Firstly, how to make mussels fail to enclose on the grilles; secondly, how to make algae and colonies be eliminated before explosive proliferation; at the last, how to make enclosing mussels and proliferating algae thoroughly be removed. These appeals all come to ask whether the synthetic biological product we devise is a long-term effective one.
Synthetic biology allows us to use genes and proteins from different sources, which could broaden our design vision further, promote our project more comprehensively, and innovatively, and solve problems in all respects. Classic tactic of synthetic biology is producing functional substances continuously via engineered bacteria and reaching aim of long-term efficiency ultimately. Comparing with various prevention measures, only the synthetic biology method with unique biological advantages come through with flying colors.
b. Consult the authoritative experts
We contacted and interviewed the scholars related to the research content of the project, and obtained a good deal of suggestions and guidance.
Danqing Feng, professor of College of Ocean and Earth Sciences in Xiamen University, said that the existing methods implemented to handle the blockage by mussels and Phaeocystis globose such as low surface energy coatings and chemical coatings have many disadvantages. Yet, the anti-fouling effect the biological active substances show is quite conspicuous, especially the biological small molecules, Prof. Feng also said. It would be very encouraging if extracellular secretion of microorganism combines with bioactive materials, the trait of which is anti-fouling.
When it comes to pick out what size of biomolecules we need, Professor Hongyue Dang, who is the Chair Professor of State Key Laboratory of Marine Environmental Science, Xiamen University, recommended the small ones, because the secretion amounts of small molecular substances could be relatively copious. If proteins were considered, the common types with high secretion would be much easy to form aggregates, let alone the denaturation and inactivation. So, we should seek for something small and robust to accommodate the sophisticated circumstances.
The research interests of Professor Xin Yu are formation and control of harmful algal bloom, and characterization of novel and emerging microbial contaminants in water treatment systems. He pointed out that when the outbreak of algae haunts the cooling system of the nuclear power plant, it is likely to be accompanied by the generation of algal colonies at the same time, so the decomposition and removal scheme of algal colonies can also be taken into account as a feasible direction.
Professor Dazhi Wang affirmed our idea, but also reminded us that what difficulties we may encounter, which advanced bacteria algaecide has not been developed for now, so we need to screen, isolate, culture bacteria which can dissolve algae cells. Prof. Wang also mentioned in the meantime that the engineering bacteria could secrete some enzymes that hydrolyze sugars, esters, or proteins of the cell walls or plasma membranes of the target cells, leading to the decomposition or death of target cells. This mechanism could be employed to design our subject, too.
All the professors praised our ideas but cautioned us to keep in mind that seawater's low nutritional environment is harmful to the growth of most microorganisms.
c. Complete specific design of the project
We conducted an extensive investigation of mussels, phaeocystis globosa and bacteria tolerant of the marine environment, and completed the specific design of the project in line with the above design ideas and the opinions from authoritative scholars. The particularly close relationship with HP is introduced as follows:
(1) Possibility of cracking the colonies
We couldn’t locate any more information on a detailed study of the composition of the algal colonies, which is critical to the fracture of them. So we asked Dr. Shufeng Zhang the composition and structure of the colonies of Phaeocystis globosa. Dr. Zhang reported that Phaeocystis globosa upregulate enzymes, such as heparanase and hexosaminidase B, to degrade heparan sulfate when stimulated by environmental temperature. We consult Dr. Zhang whether the colonies' polysaccharide is heparan sulfate, while Dr. Zhang's said there is no direct evidence shows that the component of it is heparan sulfate. Under the current study, to break down the colonies is rather tough, which is not a favorable choice.
(2) Selection of engineering bacteria
In the process of communicating with experts, many professors reminded us that the inadequate nutritional environment of saltwater makes it difficult for most bacteria to flourish. When plowing through literature and previous valuable projects, Vibrio natriegens, a kind of gram negative bacteria, comes into sight. It characterizes fast growth, substrates diversity, speedy metabolic rate, no human pathogenicity, simple genetic operation, and marked capacity for exogenous protein expression. Moreover, it can multiply well in high salty environment which is qualified to survive in the seawater. As a result, Vibrio natriegens is nominated as the engineering bacteria of our project.
Finally, integrating the ideas and ways of synthetic biology, and clues of literature and HP surveys, we settle down the plan to figure out the blockage at the inlets of nuclear plants ——"SALVAGE", acronym for Scientifically and Ably Leverage Vibrio natriegens to Alleviate the problem of P. globosa and M. edulis. We maneuver these issues by several resorts. Dealing with the mussels, the signal peptides take along with effective substances into the marine environment to undermine mussel byssus to prevent its adhesion and to destroy the adhesive proteins to remove the adhered mussels. When processing the algae, we devise specific engineering bacteria to produce indoles and rhamnolipid to kill algal monomers, preventing the explosive proliferation of algae. Suicide system is arranged to ensure the biological safety simultaneously. However, the problem about colonies need to be discussed more profoundly.
SCHOLARS
Prof. Dazhi Wang
Dr. Shufeng Zhang
Prof. Hongyue Dang
Prof. Xin Yu
Prof. Danqing Feng
Prof. Kunshan Gao
Dazhi Wang is the professor, doctoral supervisor and deputy dean of The School of Environment and Ecology, Xiamen University. Our team sent an email to Professor Wang to ask for advice about our design of algae killing. His reply to us is as follows:
"Thank you for your letter. This direction should be feasible, but it will take time. First of all, there is no mature bacterial algaecide for now, which means we need to screen, isolate, culture bacteria that can dissolve or break down algae cells. The mechanism of bacteria dissolving or killing algae are usually the secretion of some specific enzymes hydrolyzing sugars, esters or proteins in the cell walls or membranes, resulting in cellular decomposition or death. Finally, the finished algaecide should assess for on-site application and ecological risk. It would take 2-3 years to complete the entire project. I hope it will help you."
Dr. Shufeng Zhang is a postdoctoral researcher at State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University. In 2019, he engaged in the research of using transcriptome analysis to analyze the formation and degradation mechanism of Phaeocystis globosa colonies, and published an article which mentions structure of a possible material we would like to explore.
At the very beginning of our designing phase, we hoped to find some enzymes to digest Phaeocystis globosa colonies, so as to decrease size of them and prevent them from blocking filters. However, we went blind when searching for composition of extracellular polysaccharide of P. globosa colonies, therefore, we turned to Dr. Zhang for help.
First, we introduced him about our ideas and asked him about the problems we encountered in analyzing the composition and structure of P. globosa in order to seek suggestions for improvement.
In his article, he puts forward that P. globosa up-regulate heparanase and hexosaminidase B, which are capable of degrading heparan sulfate at the transcription level under the stimulation of environmental temperature, but we did not know whether it infers that the extracellular polysaccharide of Phaeocystis globosa is heparan sulfate. Dr. Zhang said there is no direct evidence shows that the component of it is heparan sulfate. Therefore, Dr. Zhang suggested that we use the instrumental analysis platform of College of Chemistry and Chemical Engineering in our school to analyze the composition and structure of the extracellular polysaccharide of Phaeocystis globosa. After revealing the monosaccharide and the main bonds, we would be able to find specific glycosidic bonds, and eventually achieve our expectation to tear the blocking colonies into small pieces.
During the preliminary research of the project, we went to the College of Oceanic and earth of Xiamen University to interview Professor Hongyue Dang.
Hongyue Dang is a Distinguished Professor at the College of Oceanic and Earth. His research interests focus on microbial adhesion, metal corrosion effects and ecological protection mechanisms and technologies. In this interview, we asked him about the relationship between biofilms formed by marine microorganisms and large fouling organisms, as well as some possible solutions for microbial fouling.
We also discussed with Professor Dang about the formation and important influence of biofilm in seawater. Besides, he presented his views on the relationship between biofilm and fouling. For methods of targeted removal of biological membrane, Professor Dang suggested us to choose engineering bacteria secreting nuclease, protease, glycosidic enzyme which can inhibit the formation of biofilm. But it is much more recommended to use small extracellular secretory molecules, because the secretion volume of smaller molecules can be larger. By contrast, protein denaturation and inactivation are more easy in seawater environment. Finally, Professor Dang reminded us to pay attention to the complexity of the seawater environment and be careful of the rigor of laboratory simulation and verification experiments.
Dr. Xin Yu is a chair professor at College of the Environment and Ecology, Xiamen University. He was once selected as a member of the National Hundred-Thousand Talents Project and the Hundred Talents Program of the Chinese Academy of Sciences. We conducted an online interview with Professor Yu Xin, introducing the preliminary ideas of our design and the problems we encountered in the project direction-.
Professor Yu first introduced many existing removal schemes for organisms in seawater systems, including physical deposition, diatom mud adsorption, chemical solutions to produce hypochloric acid into seawater to kill organisms.
Then, he put forward a few suggestions to us about our project design. First of all, it’s important to confirm which specific types of algae pose a security threat to selected nuclear power plants. The algae that cause blockage problems in different seas are different, so we should base on the actual situation to identify one or more algae as our target in order to facilitate the further design of algae removal. Secondly, algal blooms are most likely accompanied by the generation of the colonies which may also clog the cooling water system. So, the decomposition and removal scheme for colonies could also be a feasible direction for our subsequent experiment design. But Professor Yu also pointed out that the relevant research is not very comprehensive, it will be a more challenging work.
Finally, Professor Yu expressed his appreciation and affirmation to our project and wished us a smooth progress.
During the preliminary investigation of the project, we went to the College of Oceanic and earth of Xiamen University to interview Professor Danqing Feng.
Professor Danqing Feng is the vice chairman of the Marine Fouling and Anti-Fouling Technology Professional Committee of the Chinese Society of Corrosion and Protection. Her main research interest is marine fouling organisms and marine environment protection technology, which is quite fit with the problem we expect to solve. At the same time, we also knew that Professor Feng is also involved in the biological control of contamination in nuclear power plants. We briefly shared our current vision with her and sought her advice on what we expected the project to be. We also asked her a lot of knowledge for fouling prevention.
Professor Feng told us that current low surface energy coatings and chemical coatings have many defects. In fact, the microbial display technology we expected to use in the fouling prevention and control has been tried decades of years ago. But at that time, the effect didn’t satisfy, so there is no large scale usage. For the moment, active substance of biological origin shows great anti-fouling effects, especially the biological small molecules. it will be very encouraging of our project to combine microbial surface displaying with anti-fouling bio-active substances. As for the design of anti-fouling validation experiment, it is generally used to conduct validation experiment with representative fouling organisms in the laboratory, and then conduct hanging board experiment in open water. If laboratory conditions are limited, only indirect validation method could be adopted.
Kunshan Gao is the professor at the School of Ocean and Earth Sciences, Xiamen University, who has published 171 papers, including 121 SCI papers, most of which have been positively cited by scholars of the same field in their papers and monographs for many times.
We interviewed Professor Kunshan Gao online and asked him about the methods of solving algae pollution problems.
In the interview, Professor Gao mentioned that there are six main solutions for algae pollution, which are herbicides, ultraviolet light, strong oxidants such as hydrogen peroxide, mechanical removal, modified sludge adsorption, and finally the prevention of eutrophication to intercept the bloom of algal. Among them, herbicides mainly inhibit the photosynthetic process of algae and the oxidative respiratory chain through uncoupling agents.
Professor Gao also reminded us that only killing algae cells is not enough to solve the blockage. Because the colonies are still there, they can still clog the cooling water system in nuclear power plants.
3. Evaluation, verification, and optimization of project
a. Removal of colonies of Phaeocystis globosa
For the colonies of Phaeocystis globosa, we decided to change the way of our thinking which tries to solve the blockage by cracking the colonies after consulting the professors. We designed a SPY Tag-Catcher system illuminated by the high content of galactose in the colonies’ polysaccharides and the work of Peking University in 2016. This system, combined with signal peptides system, can continuously secrete SPY Tag and SPY Catcher into environment. SPY Tag equipped with galactose binding proteins can bind to galactose on the colonies, and SPY Catcher can capture SPY Tag to form gel complex and then sink the colonies to bottom of the inlet tubes.
b. Supplement and improvement to the hardware design
We also bring our design to Xiapu Nuclear Power Plant in Fujian to communicate with the engineers there to further improve our scheme and conduct field trips to further optimize and improve the hardware design to make it more suitable to the environment of the cooling water system.
During this time, we found that the water influx at the inlets is rush, so the engineering bacteria need some external forces to be fixed at the inlet, also to guarantee biosafety. So we frame a surface displaying-adhesion system for engineered bacteria in charge of solving mussel adhesion. According to the function of binding protein screening and the work of Kyoto University in 2019, we select two proteins for surface displaying: OmpA and LamB, and plastic binding protein for binding purpose. By combining them, the surface of the engineered bacteria would be filled with plastic binding protein and then the bacteria would adhere to the plastic coating of the intake grilles, which also ensures adequate contact for the functional proteins and the mussel byssus to enhance the effectiveness. Additionally, we plan to link the underwater camera system to count the number of mussels and to modulate the launchof engineering bacteria. As for the engineering bacteria seeing to preventing the congestion caused by Phaeocystis globosa and colonies, we set a floating device floating in the inlet pipe. Engineered bacteria are cultured in this floating device to release their expressed proteins without leakage of the engineered bacteria by a filter membrane with a specific size.
For stakeholders other than nuclear power plants and scholars, we had planned to conduct interviews on the staff of fish farming and fish boating to clarify the impact of fouling organisms such as mussels and algae in these industries. we visited the Freshwater Fisheries Research Institute of Fujian and the Aquatic Technology Promotion Station of Fujian, had in-depth discussions with relevant researchers, exploring human practice related to interests.
CNNC Xiapu Nuclear Power Plant
Other two stakeholders
In order to get a concrete understanding of the impact scale of the outbreak of algal red tides and adhesion of mussels to the cooling water system of the nuclear power plants, we visited the CNNC Xiapu Nuclear Power Plant which is still under construction, and interviewed Mr. Dan Wen, the Director of the Engineering Management Department of Huaneng Xiapu Nuclear Power Co..
After listening to our explanation of our project, the director suggested that the hardware we designed for sinking algae colonies should have a suitable pond-like environment to be launched. The nuclear power plant uses a lot of water, so the seawater is directly taken in and enclosed in the water channel by two typhoon dykes. It has four different types of grilles to filter the large organisms like fishes or shrimps and other materials like garbage first, and then each subunit individually takes water from the water channel through its own intake port, then re-filters water for their own usage. As the entire cooling water system is distributed throughout the nuclear power plant, the device we mentioned to collect and sink the colonies must capture and sink the colonies in the pond-like environment before it enters the cooling water intake port of each unit so as to prevent clogging of the cooling water system.
As for the hardware design of the mussels anti-adhesion, Director Wen Dan indicated that there are already underwater cameras in the nuclear power plant for observation against the grilles, but since the underwater cameras are fixed in one position, they are not similar to our hardware design for real-time monitoring in the field while moving. However, he also pointed out that the nuclear power plant itself has a fouling disposal machine, and the grilles are also treated by coating and replacing regularly so that it will not be blocked and shut down due to accidents.
The target objects of our project are mainly mussels and Phaeocystis globosa, which are Marine organisms and closely related to aquatic researches. Therefore, we visited the Freshwater Fisheries Research Institute of Fujian and the Aquatic Technology Promotion Station of Fujian, had in-depth discussions with relevant researchers, exploring human practice related to interests.
We briefly introduced the topic to the researchers. We inhibit or eliminate the adhesion of mussels by inhibiting viscosity of mussel foot protein using synthetic biological methods. The researchers mentioned the generation and the viscosity of mussel foot protein play a vital role in the function of the adhesion of mussels, confirming the reasonability and availability of our subject.
As for the hardware design of the mussels anti-adhesion, Director Wen Dan indicated that there are already underwater cameras in the nuclear power plant for observation against the grilles, but since the underwater cameras are fixed in one position, they are not similar to our hardware design for real-time monitoring in the field while moving. However, he also pointed out that the nuclear power plant itself has a fouling disposal machine, and the grilles are also treated by coating and replacing regularly so that it will not be blocked and shut down due to accidents.