Butler Oaks Farm, Inc. & FPPC, Inc.
Dairy Composting
Funded by Farm Pilot Project Coordination, Inc. through a congressional grant, RCS developed a comprehensive approach for managing manure solids from a 1,000-cow dairy. The primary objectives of this project were to remove 75% of nutrients from the waste stream, minimize capital costs, minimize operation & maintenance costs, maximize reuse, and produce a marketable end product. To this end, RCS designed and oversaw construction of
- a treatment system, composed of a sand separator for flush manure, in which sand and water were able to be reclaimed,
- a vat separator for solids removal, and
- a chemical injection system using ferric sulfate for additional nutrient removal.
Generated solids were then further processed through a screw press loader and sent to an in-vessel composting unit with a three dayturn-around cycle to produce a “value-added” soil amendment capable of being collected and marketed off site.
The system has demonstrated the ability to reach up to a 94% reduction of phosphorus concentrations. Considerable effort throughout this project focused on the compost component. Much of the testing period was spent in optimizing the dewatering of the manure solids prior to being fed into the composter. As a result of this study, the dewatering experienced in the solids settling basin was improved from 93% moisture content to 72%. As a result of this system, a total of 551 CY of soil amendment generated from the manure solids was exported offsite.
The first year revenue from the soil amendment sales was $11,020. During this time period, the daily compost production averaged 7.15 CY/day. The potential for soil amendment production from the solids generated and stored in the solids settling basins is 42 CY/day. However, the composter unit capacity is limited to 32 CY/day. During this first year of operation, a great deal of time was spent optimizing and testing the system components. If the system were to operate at the peak capacity of 32 CY/day, the projected annual soil amendment sale would be approximately $291,200.
