RESUMEN
Employing forced aeration (FA) in composting static windrows (SW) from fish waste (FW) has the potential to enhance the development of process and, organic fertiliser quality. However, due to the impact of season, the FA may lead to excessive drying of SW and, difficulty in thermophilic temperature maintenance. The aim of this study was to assess the effects of passive aeration (PA) and FA on the composting of FW in SW during the summer and winter seasons. The temperatures of the windrows remained within the thermophilic range for most of the composting period, with peak temperatures observed shortly after starting and turning the windrows (at 50 and 70 days). The aeration benefited the initial TS degradations, resulting in 86.66 and 45.99% of the TS total reduced to FA and PA piles, at 50 days during the winter. The C organic reduction was 77.77 and 76.33% in summer and winter to FA piles, respectively, but this reduction was 59.24% and 67.82% for winter and summer, respectively, in PA windrows. At 50 days, the N reduction in FA piles was already at 70.32% and 71.87% for winter and summer. The volatile solids reductions were significantly higher (p < 0.01) in FA piles during the summer. Although the FA has been shown to enhance the organic constituents' degradation during the composting of FW, its adoption was not enough to improve the compost composition. Thus, by conducting piles on a small scale, with the perforated wall, as described in this study, the FA could be dispensed.
RESUMEN
Characterizing the waste generated from different agro-industrial segments enables the strategic management of residues, with the goal of maximizing recovery within the premises of a circular economy. This research aimed to determine the coefficient of waste generated in broiler chick hatcheries as well as to characterize the waste, taking into account the points of culling and the ages of the laying hens. Furthermore, the waste was used in composting with sheep manure (SM) at increasing inclusion rates (0:100, 10:90, 20:80, 30:70, 40:60, and 50:50). On average, 0.16 kg (DM) of hatchery waste is generated per kg of broiler chicks born. At the hatchery, at least 79% of the total disposal occurs at the hatcher stage. This value is impacted by chicken age (P < 0.05), with birds of a late laying age generating waste with higher contents of carbon (C), volatile solids (VS), ether extract (EE), and nitrogen (N). Culling during egg reception and the manual transfer process account for only 1.8% of the total waste generated on average and thus contribute little to the composition of the overall residues. However, the mechanical transfer process may represent up to 19.0% of the total waste generated by hens of an intermediate laying age. According to the average of all the composting stages, the maximum reduction in solids and C from the hatchery waste was reached when the waste accounted for 50% of the windrow composition. Such conditions resulted in organic fertilizer with the highest N content (2.8%), equivalent to 40.0% more than that in the treatment with no added hatchery waste. The compost resulting from 50% hatchery waste inclusion also had the highest humic acid to fulvic acid (HA:FA) ratio and the highest calcium content due to the higher proportion of eggshells. These findings lead to the recommendation for the inclusion of hatchery waste in composting with SM at a 50% rate by mass.