Comparison of Forced and Naturally Aerated Composting of Dairy Manure Solids

Abstract

TEN compost piles of solids separated from a dairy manure slurry by a DeLaval, Lisep separator were built and observed during the period of June, 1985 to March, 1986. The study was conducted for the purpose of observing changes in moisture content and internal temperature under conditions of forced and natural aeration. Five of the compost piles were naturally aerated, and five were aerated by a fan which forced air through the pile of solids. The natural aeration process simply aged the manure solids in an unconfmed pile. The fan in the forced aeration process forced air into a perforated plenum beneath the compost piles. The fan was controlled by a temperature set point controller which sensed pile temperature. Results of this study suggest that naturally aerated static piles will achieve temperatures generally considered adequate for good composting, and will maintain elevated temperatures longer than forced aeration static piles. However, forced aeration of static compost piles of dairy waste solids appears to be superior to natural aeration if, for some reason, rapid temperature rise and high maximum temperatures are process goals. Dairy waste solids were found to dry very slowly in static compost piles. Forced aeration was found, however, to promote more rapid drying rates.