Composting Rocket: Turning Food Waste to Healthy Soil


We pursue sustainable resources for a better future for lives and the earth. We've decided to contribute to the pursuit of sustainability by participating in the Composing Rocket Project among many activities that we can choose. Our project sees food waste, which was considered waste, as a renewable resource. When we get nutrient soil, we’ll get healthy food using the nutrient soil.


Monday 10-3pm




Week 6

August, 07 2019

We faced some problems, but we have overcome them together.

The product on Monday(6th) was ok. But the composting in the machine was moldy. It looks like just decayed soil, which is good sign according to our mentor. That means more micro organisms.

I was hoping we would end this internship with such a great result, but we had a small challenge. Our product on 7th is too much moisture. It also began to smell. Odor means that there is not enough air in the rocket.

Until last week it showed good moisture and color. It smelled just like the earthy smell. The temperature in the rocket has decreased from last Thursday. Usually it was around 70°C for second channel. Now that channel is around 60°C. It has not yet returned.

We haven't figured out exactly why, but we decided to reduce the amount of water first. And no water for few days.

If you add a lot of water to the machine, the water comes out through the outlet. We used to put the water back in the machine. In some cases, the amount was two buckets (about 10 gallons) per day. So We have been having this rule for about 3 weeks. At first glance, you might think that this is the cause of the result. But, actually, the water is what we have left after we replenish it. In other words, because the amount of water initially put in was excessive, the machine drained it out. Well, at that time, we put the water back in the machine according to the instruction of the rocket. It was assumed that this was to supply microorganisms in the water to the machine.

The strange thing is that by Monday, the result was stable. Well, I felt on Monday that the rocket doesn't turn as usual by seeing that all material we put on last Thursday are stuck in the first channel. I didn't work on Tuesday, so I don't know what happened, but it doesn't seem particularly problematic. Various bacteria are currently breeding in the machine. Many bacteria and microorganisms may caused the water.

The pH level of wet result is shocking. pH 1.79 This is a stronger acid than a lemon. However, this is also an advantage. This change in pH with the amount of water means that pH 7 can be easily maintained with good water control. The former result was slightly alkaline.

Week 5

July, 29 2019

Finally, we got some good results. The color is dark black and it is moist. It has little chunk of wood chips which will be break down by worms but still look nice.

On July 22, the temperature of the second channel rose to 67°C degrees. Although this week's weather were hotter than the day(32°C), the second channel has not increased to 67°C. Thus, the interior of the machine can affected not only the temperature of the weather but also the humidity.

This week's temperature changes are interesting. According to the instructions, the second machine would be 60-70°C degrees, the third channel 60-30°C, and the fourth 30°C or less. On Monday, it was again unstable due to a monotonous down hill trend, but after that, it turned out to be a mountain shape that changed on the second channel. In addition, the difference between the first channel and the second channel is more stable than the former (1°C degree difference) approximately an average of 6°C degrees. On the other hand, the temperature of the fourth channel(50°C) should cool down a lot to be less that 30°C.

I'm worried that the pH of product is little bit alkaline. Earthworms prefer pH of 5.5-8. But now pH of product is 8.5, generally a little out of range at pH of 8.5. The reason has yet to be revealed.

Compared to last week, humidity was much improved. Now the fog has developed enough to cause the field of view to become cloudy.

We set up a voltage with mentor to see if the machine works well. We switched the voltage number to temperature using types n and k, but it does not match current temperature. It is difficult to see that there is a problem with the machine because the machine produces satisfactory results. At first, We decided to stop measuring the voltage.

I can turn the machine's internal propeller by pressing the manual button. We figured out that it takes 46 seconds per one round. Furthermore, we need to check that it is actually take about two weeks for the soil to come out as written in the manual.

Week 4

July, 22 2019

The machine is more active than ever before, but the amount of food waste is still lacking. I expect that in the new semester it will bring a better performance by having more food waste.

The pH of most objects are fine. But, we have found that the product is somewhat little bit basic. The pH of product is 8.85. Although it is not to a serious degree, the red wiggler earthworms prefer pH levels from 5.5 to 8. We expect coffee will serve as a buffer by suppling plenty of acidic coffee.

There have also been many improvements in the product condition. It looks more moist. But, I see a piece of less disintegrated wood. We discussed it would be better to use wood chips that was more shattered.

The first channel of temperature is similar to the second channel. It is a good signal. On the afternoon of the 23rd, the second channel finally passed the temperature of the first channel. The first channel is 61, the second channel is 63.

Week 3

July, 15 2019

We started to measure the pH. The pH is one of the important factors like temperature. Especially, it is important to maintain proper pH because the product will be eaten by earthworms. Wood chips, food waste in the machine, and soil were measured on 15th. All are within the appropriate level.

The soil is still arid. The cause are probably the amount of food to be fed to the machine, and the amount of water. The fact that the hose was just ready is also affected. Until now, if the ratio was about total mass for food waste and wood chips to water is 2: 1, 1: 1 will be added to the total amount of feed soon.

On July 6, when I got temperature after putting water into machine, the temperature was lowered by 11.6 degrees. I had been worried that this will affect maintaining the proper temperature inside the machine. However, since the supply of food is much larger these days, the temperature does not change much even after watering. This will have a good effect on microorganisms.

On the 16th day, the hose was broken. All hoses should be carefully wrapped so that they are not cut by the mower.

Week 2

July, 08 2019

Almost all models are built. One problem, however, is that the warehouse for the vermi-composting model is slightly smaller than the model. It is difficult to place an engine that can move the heavy contents back and forth.

Now temperature graph of each channel shows down slope without bend. However, the ideal situation is that the graph of the temperature represented by each channel shows the shape of the mountain as the second channel has the highest temperature. The cause for down slope is likely to be due to small amount of waste. There is a limit to the amount of food waste that can be collected in the school during the summer term. We always bring food waste from Dunkin 'Donuts on campus, and coffee and grass clippings are the main thing. I am worried that the coffee will oxidize the product since there is a lot of coffee.

We cleaned the machine. Cleaning the machine was well done, but one piece of drain is lost and we are going to separate the pipe in the drain for a second. It is not expected to have a significant impact on the machine, personally.

One of the problems in last year was the drain. But, more precisely, there was a problem with the fan in the drain hole, and the water was not discharged properly, which is different from the present case. I hope there is no big problem because the drainage is smooth now.

Week 1

July, 01 2019

Building the Vermicomposter

We have been attempting to figure out how to build the Vermicomposter since last Wednesday (July 3rd.) As of today, it is still incomplete, but is far more along than it has ever been in the years since it's been ordered. Unfortunately, the directions that came along with the composter were extremely unclear and did not specify how and where things were put together, leaving us to deduce the construction of the machine ourselves. We hope to get it done by this time next week, but Murphy's Law was not kind to us so far. Hope for the best and prepare for the worst! The following will be pictures of our progress so far.