Resíduos industriais como estimuladores da biodegradação de poda de árvores

Abstract

The activities related to the maintenance of the plant species in the urban environment generate tree pruning residues, which can be treated through the composting process in order to obtain a biologically stable final compound that can be used as an organic fertilizer. However, the composition of this residue hinders its degradation process, since the lignin present in its structure is resistant to the action of the decomposing fungi, which are favored in acidic environment. In this context, the composting of tree pruning with industrial acid residues may stimulate the degradation of lignin. The objective of this work was to compare the tree pruning composting process combined with organic household waste and two industrial acid residues (sludge from the dairy industry waste treatment plant and the orange juice industry waste). Physical parameters (temperature, mass and volume reduction) and chemical parameters (pH, electrical conductivity, C/N ratio, humidity, fixed and volatile solids and humic acids) were analyzed to determine which of the residues results in better degradation of tree pruning. Four treatments (T1: tree pruning + orange residues, T2: tree pruning + household organic waste, T3: tree pruning + dairy sludge, T4: tree pruning + dairy sludge + orange residues) were tested in composting beds with initial volume of 160 liters of tree pruning and 78 liters of test residue each. It was observed that T1 provided the best degradation conditions: it presented the most alkaline pH final contents, reduced about 40% of the electrical conductivity, provided the largest reduction in volatile solids contents and the largest increment in the fixed solids content, presented final humidity within the ideal limits (40 to 60%), naturally adjusted the initial C/N ratio to 29/1 and final to 13/1, presented the thermophilic phase in the active degradation phase and reduced the mass and volume by 60% at the end of the process, besides presenting one of the largest humic acids/ fulvic acids ratios. On the other hand, T4 presented the least satisfactory results, indicating that the combination of industrial waste did not favor microbial action due to the action of dairy sludge. Thus, it was possible to conclude that the use of orange juice residues in the composting process with tree pruning is a viable alternative since it provided the treatment of this industrial waste and favored the degradation of lignocellulosic materials present in tree pruning.