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For this project we were asked to measure the turbidity of the water in Lake Latin. The turbidity of the water is the number of suspended particles in the water. First, we had to understand water turbidity and the information produced by the sensor. We assembled our turbidity sensor and code and did an initial test with dirt in water to understand the results. We then tested the water of Lake Latin using the same code and testing process.
Turbidity Sensor Assembly
We used this site to help assemble our turbidity sensor. We were given a Grove Turbidity Sensor and an Arduino to power and send code to our turbidity sensor. The way the turbidity sensor works is as we place the senor in the water, a small laser is shown between the two lips of the sensor. The more light that passes to the other side without being scattered by the particles in the water produces a larger output that will be shown on the serial monitor. This means that with more particles in the water, there will be a lower output because the light will be scattered by all of these particles. We used this document to get the code for our turbidity sensor. We used this website to help set up our sensor. We copied and pasted the code into Arduino IDE, a site that sends code to Arduino, and changed the Com to the port we had plugged our Arduino and turbidity sensor into. We sent the code to the Arduino and we were finished setting it up.
This is our turbidity sensor and Arduino. The Arduino is the large blue square board and the sensor is the clear circular object attached to the long colored wires.
This is our Arduino and sensor all hooked up and connected to the computer.
This is the code we used to program our sensor. By chunk of code, the void setup chunk will only run once, which sets 9600 as the rate at which the sensor communicates with the serial monitor. Voide loop will repeat our code over and over. The analogRead(AO) is the pin were the sensor connects to the Arduino. (5.0 / 1024.0), this line is the conversion of the binary code to volts, the 5.0 representing the maximum voltage. The delay (1000) is how long the serial monitor waits, 1000 milliseconds, before printing another output.
Initial Dirt and Water Test
In order to understand and compare the results we would get from the Lake Latin water reading, we first tested the turbidity of clean fountain water and dirt. We made sure to mix the dirt and water well before testing so that the particles didn't settle to the bottom. With our sensor still plugged into our computer, we pulled up the serial monitor tab on the Arduino IDE site. When we placed the sensor in the clear and clean fountain water, the monitor showed an output of 1.24-1.25. We then dried off the sensor and moved it to the dirty water cup. The dirt and water showed and output of 0.12-0.14. These two extremes show that as the output number becomes lower, it means the water is dirtier and has more particles in it.
This is our dirt and water mixture.
This is our set-up for testing our two extremes, super dirty water and super clean water.
IMG_1241.movThis is the video our of tests, showing the two outputs,
Lake Latin Water Test
We collected some water from Lake Latin in two sports, one that is known for being gross and dirty and another that looks cleaner. We set up our electronics the same way as we did in our previous tests. We made sure to mix the water well before testing so that the particles didn't settle to the bottom. We started off our sensor in the clean water and got an output of 1.09-1.11. This was different from the test we did earlier, even though we used the same water source. We transferred the sensor to the "ok" Lake Latin water, which was a little bit yellow in color but did not have any visible particles in the water. The reading showed the output at 1.19-1.21. Then we went to the "bad" Lake Latin water which was more yellow in color and had a few visible particles in the water. This water showed a reading of 0.99-1.00. We finally put the sensor in the dirty water and got a reading of 0.4-0.43. These values all fit the assumption that the dirtier the water is the lower the output will be, besides the "ok" Lake Latin water. This value is even higher than the clean drinking fountain water. This means that this area in Lake Latin must be cleaner than we had originally thought.
These are our four water samples from left to right: clean drinking fountain water, "ok" Lake Latin Water, "bad" Lake Latin Water, and dirty water.
IMG_1250.MOVThis is our final test of all four types of water.
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