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Building a Bioreactor for Kombucha
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Please be positive and constructive with your questions and comments.

Building a Bioreactor for Kombucha

by EnchantressOfNumbers07 on Fri May 08, 2020 8:53 pm

I want to build a bioreactor to make kombucha but to do so I need to find a microcontroller that can sense pH, oxygen, temperature, and sugar in water. What microcontroller(s) & sensors would be good for this project?

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Re: Building a Bioreactor for Kombucha

by adafruit_support_bill on Sat May 09, 2020 6:44 am

We have sensors for temperature. The DS18B20 would be a good choice. See this guide for precision temperature control using an Arduino and the DS18B20: https://learn.adafruit.com/sous-vide-po ... us-viduino
For pH and Oxygen sensors, I'd check with aquarium specialist sites.

Unfortunately, the only glucose sensors I know of for monitoring bioreactors are part of some rather expensive lab equipment. The measurement involves extracting a sample from the reactor, and mixing it with precise quantities of reagents (the precision robotics behind that operation are a good part of the expense) before bringing it into contact with an amperometric sensor to measure the results.

You might be able to make something workable using a home blood glucose meter.

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Re: Building a Bioreactor for Kombucha

by EnchantressOfNumbers07 on Sat May 09, 2020 9:30 pm

Thank you so much for the information! I was wondering if the Arduino could handle so many sensors. Would it be theoretically easy to say for instance "if pH > 7, lift hatch/pump to let lemon juice in; if O2 < 5, pump more O2" (just an example)?

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Re: Building a Bioreactor for Kombucha

by adafruit_support_bill on Sun May 10, 2020 6:13 am

I was wondering if the Arduino could handle so many sensors.

An Arduino should be able to handle it. Fermentation is a relatively slow process, so processor speed should not be an issue. Unless you are planning a fancy graphical user interface, memory should not be an issue either. Pin-count requirements will depend on the sensors and actuators you end up with. I2c sensors can all share the same 2 i2c bus pins. Analog sensors typically need one analog pin each. If you use servos to operate your valves, you would need just one pin each for those.

Would it be theoretically easy to say for instance "if pH > 7, lift hatch/pump to let lemon juice in; if O2 < 5, pump more O2" (just an example)?

For stable control, you will probably want to at least use some sort of proportional control. So the amount of lemon juice added would be proportional to the difference between the measured pH and the setpoint value (7).

The guide linked in my previous post uses a Proportional/Integral/Derivative (PID) control algorithm for the temperature.

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Re: Building a Bioreactor for Kombucha

by EnchantressOfNumbers07 on Sun May 10, 2020 6:52 pm

Thank you again for your response! I wanted to know if there are some compatibility issues if I use sensors from aquarium sites. Should

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Re: Building a Bioreactor for Kombucha

by adafruit_support_bill on Sun May 10, 2020 7:44 pm

I wanted to know if there are some compatibility issues if I use sensors from aquarium sites

Most should be able to be accommodated.

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Re: Building a Bioreactor for Kombucha

by EnchantressOfNumbers07 on Mon May 18, 2020 1:17 pm

Thank you again for your patience with me thus far. I was wondering if I could build a similar system with a Raspberry Pi Zero since I have one on hand and my code expertise is in Java and Matlab. If so, where can I find compatible sensors?

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Re: Building a Bioreactor for Kombucha

by adafruit_support_bill on Mon May 18, 2020 1:41 pm

You might want to take a look at the Reef-Pi series of tutorials here: https://learn.adafruit.com/search?q=reef-pi
These deal with controlling a reef aquarium with a Rspberry Pi, but he is measuring many of the same parameters you are interested in.

For temperature, he uses our DS18B20: https://www.adafruit.com/product/381
For pH he uses a sensor from Atlas Scientific: https://www.amazon.com/dp/B00641R1PQ/

He has not written the section on dissolved oxygen, but I believe he will be using one of the Atlas Scientific sensors for that too.

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