Treatment of the chromium-containing solid wastes from leather industry: use in adsorption process and as nitrogen source in agriculture. / Tratamento de rejeitos sÃlidos contendo cromo da indÃstria de couro: uso em processos de adsorÃÃo e como fonte de nitrogÃnio na agricultura.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The leather industry has a great economic importance for Brazil, however it is responsible for the generation of solid wastes containing chromium (sawdust and stripes of wet blue leather), which need suitable disposal for being classified as class 1 waste. The objectives of this work were to treat this waste for chromium removal and to use the resultant material (collagen) in two processes: (i) adsorbent of organic contaminants; (ii) nitrogen source for plants. The samples of wet blue leather were supplied by Nunes Tanning Industry (located in the city of DivinÃpolis - MG) and the soil used in the tests of the material as nitrogen source was a Yellow-Red Latosol (collected in the city of Juiz de Fora - MG). The experiments were done in three stages: (i) hydrothermic treatment of the leather for chromium removal, (ii) use of the materials (wet blue waste and collagen) as adsorbents of the organics dyes methylene blue and reactive red and (iii) use of the collagen as nitrogen source for elephantgrass and common bean plants. In the stage of chromium removal, the extraction efficacy was of 99,6% (w/w), obtained with acid hydrolysis done with phosphoric acid. In the second stage of the work, the wet blue leather waste and the collagen (material after chromium removal) were efficient for the removal of the anionic dye reactive red, with adsorption capacities of 163 and 100 mgdye g-1material, respectively. In the adsorption of the cationic dye methylene blue the materials were less efficient, adsorbing only 8 mgdye g-1material. In the third stage of the work, the material was applied as nitrogen source for elephantgrass in the doses (0, 4, 8, 16 e 32 t ha-1). At the end of this culture, it was prepared an experiment with common bean plants in the same vases to verify the residual effect of the nitrogen from the collagen applied to the elephantgrass culture. The collagen showed to be a good nitrogen source, therefore for the doses of 4 and 8 t ha-1, presented elephantgrass production superior to the conventional manuring ((NH4)2SO4 and NH4NO3). It is important to say that the material was efficient as organic source of nitrogen only after the chromium extraction.

ASSUNTO(S)

colÃgeno adsorvente recycling reciclagem wet blue leather couro wet blue nitrogen fertilizer fertilizante nitrogenado collagen quimica adsorbent

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