1999 Annual Report for FS99-105
Low Cost Compost Screening
Summary
Municipal yard waste is an abundant natural resource in the areas of the south with hardwood trees. Composting often is accomplished at the waste facility, and they give the material away in most cases. Utilizing this resource in organic potting mixes for mulching and for increasing organic matter in the soil makes sense. Unfortunately trash, rocks and other debris pollute what would be an excellent source of organic matter.
The goal of my project is to construct a screener out of stock parts with minimal modifications. I will modify an existing three-point-hitch concrete mixer to remove the contaminants from yard waste. A farmer with a reasonably efficient screening system would be able to utilize unscreened yard waste from a nearby facility, reducing the need to go farther from the farm and transport a higher quality product long distances. My research has convinced me that the orbital action of a trommel type screener is more efficient than a vibrating screen method. A larger custom-built cylinder will increase the cost, but the increase in capacity would likely be worth it. Estimating the cost of a custom cylinder is difficult without first modifying the stock cylinder in this project.
To determine the best cylinder shape and size it will be necessary to first modify the cylinder that comes with the implement. This will be done by cutting a series of rectangular openings around the circumference and securing rabbit-wire screen over these openings. To make this as versatile a machine as possible, the ease of changing screens for various mesh sizes will be a priority. After determining the effectiveness of this idea with stock parts, the next step would be to increase the size and adjust the shape of the cylinder to increase the capacity of the screener to meet on-farm needs.