Compostagem como alternativa para gestão de resíduos gerados pela indústria da água-de-coco.

Abstract

The consumption of coconut water has been growing significantly in recent years and, consequently, there is a greater demand to produce the fruit still unripe, which generates an environmental liability, which are the fruit peels. Furthermore, the bark is difficult to decompose due to the high levels of cellulose and lignin in its composition. In this context, the aim of the present study was to evaluate different formulations of composting coconut husks over time. The experiment conducted out in the composting yard at Fazenda Reunidas Socôco®, municipality of Santa Izabel do Pará, in the Amazon region. The experimental design was randomized blocks in a factorial scheme (5x6) of five treatments (T1: Crushed Coconut Shells (CCT); T2: CCT + 3% poultry litter (CA); T3: CCT + Inoculant (IN); T4: CCT + 3% CA + IN; T5: CCT+5% CA) and six composting times (0, 12, 24, 36, 48 and 60 days) with four repetitions. The contents of nitrogen, phosphorus, potassium, calcium, magnesium, iron, aluminum, sodium, organic carbon (Corg), organic matter (OM), ash and carbon/nitrogen (C/N) of the compost were evaluated. The results were submitted to analysis of variance and Tukey test at the level of 5% probability (p<0.05) using the SISVAR statistical program. Pearson correlation (p<0.05), clustering and Principal Components (ACP) analyzes were also performed using the R Software. There was a significant reduction in C/N, Corg and MO, although the treatments did not differ from each other for variables Corg and MO, and increase in the contents of N, P, Fe, Al and ash in all treatments after 60 days of composting. T2, T4 and T5 reached an adequate C/N ratio (<33) for use as fertilizer faster (36 days), higher values of N, P, Ca and Mg, in addition to lower C/N ratios at 60 days. The C/N showed a strong negative correlation with the N content and moderate with the P, Ca and Al content, in addition to a strong positive correlation with the MO and Corg content. The cluster analysis showed that the chemical characteristics of different formulations change over time, favoring the formation of groups influenced mainly by nutrient content and C/N of the material. ACP showed that the reduction of C/N over time is strongly related to waste mineralization processes. Therefore, the results of this research demonstrate that the composting of green coconut fiber, with the addition of CA, is effective in reducing the C/N to values suitable for application to the soil in a shorter time, reducing the compost yard time and, consequently, the operating costs involved in the large-scale composting process.