**Figure 8.**

*This mechanized device is pulled by a tractor and is used to shape, turn, or churn the compost in the windrows.*

As an alternative to windrows, smaller operations will use what is typically referred to as the in-cell technique. As its name suggests, this approach uses modular structures that hold the compost in place and look somewhat like a large cube [7]. The biggest advantage of the in-cell or 3-cell technology are that they can be maintained using manual labor and do not require expensive machinery such as a tractor and windrow turner for turning or churning the compost mix while it is in the process of decomposition. There were some obvious reasons why the in-cell composting technique was employed at the compost operation in Guatemala. These include the following:

• By using manual labor to move the compost from one cell to another and thus accelerating the decomposition process, more youths could be employed;


The in-cell compost technique looks much more like the compost "bin" that a homeowner might use for decomposing kitchen and yard organic waste (**Figure 9**). Home-composting typically has one compost bin/cell. Yes, some households can and do have multiple compost bins, however the contents are seldom mixed or shoveled into an adjoining bin. For this reason, three cells should be employed to be more effective (**Figure 10**). But why three cells? One should begin with a new compost mix that is started in cell A: once the contents begin to shrink in size as the green waste decomposes, all of the contents from cell A should then be shoveled into cell B and a new batch started in the now available cell A. The act of moving the mix from cell A to cell B adds oxygen and mixes the contents, similar to what a windrow turning machine might accomplish. Later, the contents from cell B are moved into cell C for completion, and a new batch is begun in cell A, which has seen its material moved into cell B.

There are perhaps many ways to construct cells for producing compost, all based on the availability of cost-effective materials and creativity of the builder. Wooden shipping pallets were selected for use at the CENMA site because they are inexpensive and were easily obtained. Each of the shipping pallets were simply fastened together using long screws or nails to join one to another (**Figures 10** and **11**). Small sections of chain link fencing were used to enclose the front opening for each cell. Initially, the intention was to use steel fencing post which would be hammered into the ground forming each of the corners, coupled with welded wire fencing fastened to the posts to form the enclosed sides. However, the hard and rocky surface area found at the test site rendered this approach unfeasible as it was impossible to drive the metal posts into the ground. The wooden shipping pallets were readily available, easy to fasten together, and inexpensive.

For a newly established compost pile (in cell A), one must regularly monitor the internal temperature during the initial weeks to determine the rate of

**Figure 9.** *A compost bin or cell is used to make compost from household green waste, fallen leaves, and grass clippings.*

#### **Figure 10.**

*This schematic illustrates how wooden pallets can easily fastened together as a three-cell compost system (illustration by Seth Morrow).*

**Figure 11.** *Wooden shipping pallets are readily available and can be simply fastened together to replicate the three-cell compost system.*

decomposition (or cooking as it is referred to). At the same time, the size of the pile decreases or shrinks in size as the green material breaks down. Similar to that of a windrow, a thermometer with a long one-meter probe is used to measure the internal temperature (**Figure 12**) to determine if and how fast the compost process is successfully occurring. **Table 2** illustrates cell-monitoring data for one of the two test cells constructed. The data was monitored in order to chart the time and temperature on a weekly basis, in addition to observed odor (smelliness). Approximately one month after the pile is made, the temperature cease increasing while the shrinkage of the pile should also decrease in rate. When this occurs, the pile should be shoveled into cell B. This process of turning the pile simply involves taking the material out of the cell and mixing it up, meaning that it is important to move the decomposing material from the middle of the pile to the outside layers of the relocated pile, now in the second cell (cell B).

*Compost, Social Sustainability, and Circular Economy in Guatemala DOI: http://dx.doi.org/10.5772/intechopen.100280*

**Figure 12.** *Decomposition temperature is monitored regularly using this thermometer with a 1 meter long probe.*

The microorganisms should be actively feeding on the organic material, meaning that they are now consuming the composting mass of material. Obviously, the microorganisms do not have the ability to move very far, so it is very important to adequately mix the pile, putting the microorganisms into direct contact with organic material to continue the decomposition process. Whereas the turning of a pile will introduce oxygen, it is quickly consumed, and it is not the primary function of turning or mixing the contents. Oxygen should enter a compost pile through proper ventilation and pore space (voids in the mix). Some people will also include perforated plastic pipe, similar to that used for stormwater under-drainage, and place the pipe across the bottom and then extending perpendicularly and vertically up through the pile to better allow the movement of oxygen.


*The units for Height are in inches, Temperature is in F, and Humidity is based upon relative %. Smell was subjective with 1 being low and 3 being high.*

**Table 2.**

*The rate of decomposition, changes in temperature, humidity and odor were monitored weekly in each of the test compost cells.*
