This project is another type of anaerobic reduction (non-oxygen-loving microbes) of biomass called fermentation. We use black plastic bags to capture the sun’s energy to help heat and speed up the composting process even further. Fermentation is a chemical change brought on by the action of microscopic organisms such as yeast, molds and bacteria. The souring of milk, the rising of bread dough, and the conversion of sugar to alcohol are all examples of fermentation. Alcohol is produced when yeast enzymes break up sugar into roughly equal parts of alcohol and carbon dioxide gas.
Everyone may be familiar with baker’s yeast, but most yeast occurs wild in nature and grows on plants and animals, by which it is dispersed through the air and water. Yeast spores are
everywhere, and if they get a chance, they will gladly ferment your biomass waste, feeding off the waste’s sugars, starches, and cellulose fibers. There are thousands of strains of wild yeast, and with the help of their enzymes, you can make a
supercompost that is rich in helpful enzymes.
Enzymes in the soil can degrade complex organic compounds into nutrients for plants and contribute to carbon turnover, providing energy for plant growth. Carbon-degrading enzymes are abundant in all healthy soil. By adding or increasing enzymes in soil, we are naturally helping in the cultivation of plants for food, energy, and industry.
Fermentation is an anaerobic conversion of sugars to carbon dioxide and alcohol that breaks down complex organic compounds into simple substances while producing enzymes. The alcohol produced during fermentation is called ethanol, like that found in wine, beer, and liquors. This ethanol is beneficial in helping to keep competing microorganisms such as black mold and other less beneficial microorganisms at bay. The fermentation process speeds up the production and reproduction of the enzyme proteins we want and also forms simple plant nutrients.
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Figure 7-13
T I P
I Active dry yeast (the stuff sold for making bread)
I Compostable materials (kitchen waste, grass, leaves, and paper)
I Water
I Sugar
I Heavy (3-mil-thick) black plastic 40- to 50-gallon trash bags (nonbiodegradable so as not to break down, fail, or spill)
I A sunny location with warm days
I A 2-cup (500-milliliter) measuring cup
I A 5-gallon bucket
I A rubber band (Figures 7-14, 7-15, and 7-16)
W H A T Y O U ’ L L N E E D
104 Recycling Projects for the Evil Genius
Let’s Start
1. Find a nice sunny spot to work with your black plastic bags (black collects heat from the sun).
2. Add five 5-gallon (18-liter) buckets of biomass (leaves, grasses, and kitchen waste) to each bag. Be careful not to punch a hole in the bags. You don’t want leaks. Fill each bag where you are going to let it sit in the sun so that you don’t need to move it again (Figure 7-17).
3. Now fill the 5-gallon bucket about two-thirds full of room-temperature water, add 5 pounds (2.26 kilograms) of sugar, and stir it well to dissolve the sugar as best you can (Figure 7-18).
4. Add 5 tablespoons (150 milliliters) of dry active yeast to the water and sugar solution, and mix it all together (Figure 7-19).
5. Pour the sugar, water, and yeast solution into the bag.
6. You want the contents of the bag to be
soaking wet, so if you used biomass with a lot of surface area, such as leaves, you may need to add more water.
Figure 7-14
Figure 7-15
Figure 7-16 Figure 7-17
7. Once everything is soaking wet, grab the bag and loosely bundle it together in your hand.
8. Slowly squeeze out as much of the air as you can from the bag.
9. Now close the top of the bag using a rubber band to hold it shut, but not so tight that gases are prevented from escaping. During fermentation, CO2is created, and the bag will puff up as this happens. You don’t want the bag to burst, so having a relatively loose seal is important. At the same time, you don’t want outside air and other microbes getting into the
bag, so sealing it too loosely is also not a good thing (Figure 7-20).
10. Let the bag sit in the sun soaking up the sun’s heat during the day and holding it at night, and in two to three weeks, the fermentation should be finished. If not, add more sugar, and give it more time.
How to Use It
1. We first need to separate the liquids and the solids, so by hand (wear gloves if you want), pull out as much of the solids as you can and put them in the bucket. When the bucket is full, put its contents in with your other compost or soil, and blend it in well. Repeat this step until the bulk of the remaining solids is removed.
2. Pour the liquid contents into your empty bucket, and use them as a superplant food by mixing them first with water at 1 tablespoon (30 milliliters) of compost liquid enzyme per 1 gallon (3.8 liters) of water. Spray it and pour it on your plants to make them healthy and to discourage pests.
Chapter 7 I Solar-Powered Compost Projects 105
Figure 7-18
Figure 7-19
Figure 7-20
3. You can also use 1 gallon (3.8 liters) of the liquid as a culture in place of the yeast for your next bag of solar-powered compost.
4. The liquid also can be used to boost water-based cleaners around your home, just like the cleaning enzymes in Chapter 8.