After food scraps and other compostable materials complete their 21-day cycle in the anaerobic digester, the material is transferred to Keith Day Company for an outdoor composting process that lasts 60 – 90 days. The material is placed in long “windrows,” where the product is allowed to reach approximately 150 degrees and turned a minimum of 5 times, until the organic materials have decomposed into a fine soil amendment.
After composting, organics are carefully screened, or sifted, to ensure the finished compost is free of contaminants.
Quality control is essential in every step of the program. Before food scraps leave commercial properties and special events, haulers and The Offset Project (TOP) work with staff to ensure they are educated in proper source separation. Loads are inspected again once they reach MRWMD and contaminants, such as plastic and aluminum foil, are removed.
Finally, the material is mixed with mulch made from landscape trimmings and loaded into the anaerobic digester units for 21 days. After anaerobic digestion, the organics then compost in windrows for 60-90 days. The finished compost is then mechanically screened and sifted.
Routine testing of the finished compost has shown the NPK content to be: N = 1.2, P= .21, K = .31. The compost also tests free of all trace metals and pathogens.
This process turns a material that would otherwise be considered “waste” into a high quality soil amendment. Using compost is a great way to return nutrients to the soil, improve soil structure and water retention, and sequester carbon. Organics to Energy compost is sold to local vineyards and orchards by Keith Day Company.