The Effect of Aeration on in-Vessel Compost Processing and Quality.

The University of Arkansas spends approximately $14,553 each year on food-waste disposal. On campus composting could reduce this cost and simultaneously promote the University’s sustainability initiatives. Composting in a closed, in-vessel system such as an Earth Tub™ offers the advantage of containing food waste as it accumulates to an amount sufficient for composting in a small-scale operation. Furthermore,   control of the composting atmosphere may also be an advantage. Aeration is an important factor in composting, as it modifies moisture and temperature, both of which affect the microbial activity necessary to compost. The goal of this research was to determine the effect of mixing frequency (for aeration) on in-vessel compost processing. Pre- and post-consumer food waste  feedstock was combined with  wood chips  as a bulking agent. A 3 days/week versus 7days/week mixing/aeration schedule was compared. Compost processing was evaluated by measuring  temperature, pH, electrical conductivity, and moisture content over time. Preliminary results suggest that moistures were very high (> 50%) during bin filling and a final 30-day composting period.  The  pH in the 3 days/week treatment decreased after several weeks and was often lower than in the bin being mixed 7 times per week, Both treatments remained above the recommended 3500-6400 dS/m EC level. In-vessel composting may provide a mechanism to hold accumulating wastes and facilitate the compost process under a controlled atmosphere; however, important logistical constraints such as maintaining optimal moisture contents to facilitate aerobic decomposition during composting need to be optimized before efficient compost processing can be expected.