Effects of aeration and season on the composting of slaughterhouse waste

Abstract

The necessity of forced aeration (FA) in static windrows should be evaluated with caution since the adoption of composting cells with partially open walls can favor the process and dispense the need for aeration. We aimed to evaluate the influence of aeration and season in composting cells with perforated walls (CCPW) using bovine slaughterhouse waste (SW) associated with a bulking agent. The windrows built in winter, without (WA) and with aeration (A), maintained average temperatures of 55.8 and 57.5 °C for 66 and 53 days, respectively. This period was shorter than that observed in summer windrows (71 and 72 days, WA and W, at temperatures of 55.9 and 53.7 °C, respectively). The presence of FA in the windrows conducted in the summer did not influence (p > 0.05) the reduction of total solids (TS), C, ether extract (EE), and neutral detergent fiber (NDF) at 90 days, while the FA during the winter provided a lower degradation of the evaluated constituents (TS, C, EE, and NDF). FA did not influence N losses during the summer, but accelerated those observed in the initial composting phase during the winter (40.16 and 48.25% of N losses, at 50 and 70 days of composting, respectively), compared to WA condition (32.04 and 44.09%, respectively). FA did not minimize N losses, and also did not improve the levels of other nutrients. Thus, we can conclude that composting of SW in CCPW dispenses the use of FA during the winter or summer. • Composting cells with perforated walls (CCPW) are efficient in static piles. • CCPW are efficient to dispense aeration during slaughterhouse waste (SW) composting. • The forced aeration during the winter reduces the degradation of organic matter. • The low air humidity in the winter slows down the biodegradation process.