Caracterização química de resíduos da produção de biodiesel compostados com adição mineral / Chemical characterization of residues from biodiesel production composted with mineral addiction

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The production of biodiesel has in agriculture its base of sustentation. The culture of sugar cane and oleaginous species as castor oil plant after processing to obtain alcohol and vegetal oil, respectively, generates organic residues. These residues when used in agriculture in the compost form make possible the reduction of production costs and increase of the agricultural productivity, and if destined in inadequate places cause environmental pollution. The compost enrichment may promote the retention of the mineral nutrients in humic substances (HS) and its gradual release to plants with the compost mineralization. Besides, it may contribute to form different amount and quality of HS. The enrichment may be made with high and low solubility fertilizers, inclusive with rocks that contain primary minerals. In addition to Si from the bagasse of the sugar cane, organic acids formed during composting can act reducing the phenomenon of P adsorption, increasing P availability. This work was carried out to analyze the effect of compost enrichment on the quantitative and qualitative changes of HS, the agronomic potential and pollution effect of compost. It was carried four experiments to achieve our goal. In the first experiment it was evaluated quantitative changes during the composting of eight composts obtained from the mixture of following wastes: sugar cane bagasse (SCB), ashes of sugar cane bagasse (ASCB), poultry manure (PM), filter cake (FC) and castor oil plant residue (Ricinus communis, L.) (MR). The treatments were prepared by mixing the material in the following combinations: a) SC: SCB + ASCB + PM; b) UR: SCB + ASCB + PM + mineral fertilisers NPK, where N: urea; c) AS: SCB + ASCB + PM + mineral fertilizers NPK, where N: ammonium sulphate; d) SM: SCB + ASCB + PM + serpentinite and micaxist powdered rocks; e) PR: SCB + FC; f) FC: SCB + FC; g) M+G: SCB + MR + gneiss powdered rocks; and h) M-G: SCB + MR. The composts were sampled at 0, 30, 90 and 120 days after starting composting. It was measured pH, EC, C, N, humic substances, fractionation of light organic matter in cellulose, hemicellulose and lignin, and water soluble C in all stages of sampling, and chemical characterization of the stabilized compost. The composts that contain FC and MR presented the greatest content of HA (humic acids) and FA (fulvic acids). Losses of C were smaller in the compost of SCB + ASCB + PM base, if excluding compost SM; the FA content was more influenced by the treatments than that of HA; the mineral enrichment with SM promoted the formation of more polymerized humified material, while of reverse was found for AS, less. The second study involved the extraction and purification of HA and FA from the composts, which were then characterized qualitatively by means of analysis of CEC, index of germination, elementary analysis, thermogravimetry (DTG, DTA), infrared, UV-visible, and 13C-NMR spectroscopy of and molecular diffusion coefficient. The quality of the HS formed was affect by the treatments. The composts of SM and FC showed greater CEC; the HA was more aromatic in the treatments with mineral enrichment and the FA from AS compost was less aromatic; the treatments influenced the formation of oxygenated functional groups, if excluding composts SM and FC. The third study evaluated the compost pollution potential using leaching columns, which were incubated by 7 days, followed by the applications of five water in day 0, 7, 14, 21 and 28. The leached material was collected and reserved for analyses of C, NO3 - and P. The losses of C and NO3 - through leaching was more intense after the first application of water; the composts M+G and M-G presented greater losses of C and NO3 - and smaller of P; the mineral enrichment with SCB + ASCB + PM contributed to lower losses of C and P, and greater of NO3 -. The last study was carried out in a greenhouse using a loamy dystrophic Oxisol, which was cultivated with sugar cane. The EC, soil fertility, equilibrium P, "available" Si, total organic C, total N and humic substances were analyzed in the soil. For plants, it was determined dry biomass, and nutrients concentration in leaves after 150 days of planting. The composts met the nutritional requirements of the sugar cane; the production of dry biomass of the treatment with 35 Mg ha-1 composts was similar to the mineral fertilizer treatment; the compost containing ASCB did not contribute to a high content of Si in the soil, and no effect on the reduction of the soil adsorption of P; HA of the composts contributed for reduction of P fixation.

ASSUNTO(S)

lixiviação ciencia do solo humic substances substâncias húmicas compost sugar cane cana-de-açúcar composto orgânico

ACESSO AO ARTIGO

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