Combination of biological processes for agro-industrial poultry waste management: Effects on vermicomposting and anaerobic digestion.

This study evaluated the combination of bioprocesses to increase the utilization of agro-industrial poultry wastes. Composting piles were submitted to hydration and fraction separation (FS) and then, the solid fraction was vermicomposted and the liquid fraction was anaerobically digested. Composting followed by hydration and FS prior to vermicomposting enhanced earthworm adaptation and survival by reducing salt levels (50%), total organic carbon, and total nitrogen which may be limiting to vermicomposting at high concentrations. These strategies providing the production of up to 300 new cocoons and 360 young earthworms more than the control treatment. In addition to providing a favorable environment for earthworm growth, the combination of bioprocesses resulted in a high-quality organic fertilizer free of phytotoxic compounds and with phytostimulant properties (germination index higher than 100%). Energy recovery was greater in the treatment without the precomposting step (T0) (461.8 L CH4 kg-1. Volatile Solidsadded). The results show that combining the bioprocesses is a sustainable alternative for managing poultry wastes not only in terms of the recycling of nutrients but also by providing a clean source of energy.

Semi-continuous anaerobic co-digestion of flotation sludge from broiler chicken slaughter and sweet potato: Nutrients and energy recovery.

Energy production based on the proper allocation of environmental liabilities is in line with the concept of sustainability. Flotation sludge (S) is a type of waste derived from the physical treatment of the wastewater generated in significant quantities during chicken slaughter in Brazil. If not treated, this wastewater may contribute to pollution, but further treatment provides clean energy and nutrient recycling. The present study aimed at evaluating the reduction of (S) organic load by means of mono and co-digestion with sweet potatoes (P) while promoting its conversion into energy (methane) and nutrients (digestate). Semi-continuous reactors (60 L capacity) were used with a hydraulic retention time of 25 days. The reactors were fed daily with 2.4 L consisting of 60% digestate recirculation, 40% non-chlorinated water and 4.5% total solids (TS). Using nine reactors and six progressive periods, eleven conditions were evaluated with three replicates each. The percentages of (P) and (S) varied from 0 to 100. The best observed condition in terms of energy recovery and TS removal was 60% of P + 40% of S (p ≤ 0.05), as it presented values of at least an increase of 92% in total biogas volume, an increase of 123% in specific methane production, an increase of 98% in specific methane yield and an increase of 44% in TS removal efficiency compared to mono-digestions. The fertilizer potential of the digestate generated in the different conditions was calculated and evaluated according to the area of (P) production. The results varied from 3.6 to 10.8 ha of (P) using 100 m3 of digestate. A multivariate analysis showed that higher amounts of (P) in substrate composition favor energy recycling while higher concentrations of (S) enhance the production of a digestate with valuable agronomic characteristics.

Combining pre-treatment strategies for broilers industry waste valorization.

aiming at expanding the possibilities for broiler slaughter wastes valorization, composting piles were submitted, at different time points (T0, T10, T20, T30 and Control) representing the treatments, to a solid-liquid fraction separation (FS), after being submerged in water (2:1, water:compost, in the fresh weight). After FS, solid material separated with a strain was again placed in piles for the final stage of composting, being evaluated the organic composts obtained after the stabilization phase (65 days) and maturation (95 days), in the different treatments. Reductions in mass (60-62%) and volume (56-64%) were greater in piles submitted to FS in comparison to control piles (52% and 54%). On the other hand, the FS induced greater losses of C (70.3-71.3%), N (55-62%), P (41.7-54.4%) and K (62.3-72.1%) in comparison to the control (65.2%, 48.0%, 28.1%, and 37.6%, respectively). We conclude that, as a way of integrating bioprocesses, FS does not have negative effects on the composting process. Moreover, compost mixtures from FS-treated piles, when used as substrate, yield better seedlings in comparison to mixtures from control.