This paper reports on trials conducted to determine the effect of bulking agent particle sizeon windrow pile temperature. Woodchips, prepared from wood waste obtained from a pallet manufacturer,were used in the study. Three windrow recipes were made using a recipe of one part biosolids to 2.5 partswoodchips (vol:vol) at a target moisture content of 60%. Three treatments were investigated: (1) fine:100% fine wood chips; (2) medium: 50:50 fine and coarse woodchips; and (3) coarse: 100% coarsewoodchips. Characteristic particle sizes (equivalent to the screen size passing 63.2% of particles) were40, 13, and 5.2 mm for the coarse, medium, and fine material, respectively. Each treatment was replicatedtwice for a total of six piles. It was found that finer particle sizes resulted in thermophilic temperaturesbeing reached sooner, being sustained for a longer time, and recovering more quickly after rainfall events.Based on the experimental observations, it was assumed decreased tortuosity in the coarse woodchipmaterial led to higher ventilation rates as compared to the finer material. Further experimental work isrequired to confirm this. The authors' recommend operators characterize feedstock bulking agent sizeparticle size distribution, particularly at facilities purchasing bulking agents for their operations.
展开▼
