Nearly 30% of CO₂ emissions are attributable to industries. The goal of our project is to solve the CO₂ problem by using engineered E. coli to fix CO₂ emitted from industries and convert it into bio-product, pyruvate. To accomplish our goal, we designed a device that will upscale our project to be used on field and we aim to integrate the device into industrial IGCC system. And we used the Arduino to sense the pH, CO₂ concentration and temperature then use the Wi-Fi sensor to upload to the database. Last but not least, we can monitor the condition of our device by showing data in our App.

Fig 1.Desin of our device

Our device consists of 4 main parts : a bioreactor, a nutrient tank, a collection tank and Arduino sensors. The flue gas from industrial contains high concentration of CO₂ which will inhibit the growth of E.coli. Thus, we will decrease CO₂ concentration level to less than 5% at the inlet of bioreactor. With a flowmeter, we can measure the flow of gases in pipelines.

For Arduino, we use thermometer (DS18B20)、pH meter and CO₂ sensor (MG811) to monitor our device. Besides, the LCD will print datum while the Wi-Fi sensor (ESP8266 Nodemcu) will upload our records to database. You can see more information about arduino code in software.

We developed a closed system on in our bioreactor design and implemented online real time monitoring system which can determine the progress condition of bioreactor.

The gas inlet port is located on the bioreactor’s lower part while outlet port is located on the bioreactor’s upper lid. As low concentration CO₂ enters the bioreactor, it flows through the diffuser refiner and dissolves in the buffered medium to form acid. A pH sensor and a thermometer is installed to monitor the bioreactor tank for further control implementation. Besides, the CO₂ concentration level of exhaust gas is monitored by a CO₂ sensor, which is mounted on the upper lid. These sensor’s output is connected to an Arduino analog input and sensor readings are displayed on a serial LCD which is attached on the lid of bioreactor. The data is then uploaded in real time to a web server via WiFi by using Arduino WiFi Shield.

To prevent sedimentation of cells at the bottom of bioreactor, we build our own slow speed magnetic stirrer of 3D printed materials which permits gentle mixing of microcarrier cell cultures. The 3D printed magnet bed is designed specifically for two magnets and can be fitted on the DC motor. The stirrer works by using a DC motor to spin two magnets with opposite polarity, which could create a magnetic field in the bioreactor and cause the stir bar to spin and mix the contents. For controlling the speed of the DC motor, we use Arduino and L298N to control the input voltage to the motor by using PWM signal.

Besides, we also implemented fed-batch culture system in our design. Nutrients are fed to the bioreactor during cultivation to prevent nutrient depletion. The nutrients are pumped into the growth chamber at a rate proportional to the growth factor of the culture, which is determined experimentally through the doubling time of the particular bacterial strain.

In order to simulate the situation of the industry, two electromagnetic valves are installed on the input and output of the collection tank and the medium tank, they can be controlled by the App.

• Acrylic Sheet
• Arduino UNO
• Power Supply
• Batteries
• Rotameter
• pH meter
• Thermometer (DS18B20)
• CO₂ sensor (MG811)
• Wi-Fi sensor (ESP8266 NodeMcu)
• Geared DC Motor
• Tubes
• Magnets
• 3D Printed Structure
• Nuts and Screws
• Wires
• Pumps