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Brazil has one of the largest herds of cattle in the world, with more than 170 million heads. Over 400 farms have exported more than 2,875 ton (in 1997) of leather to Europe. The wet blue tanning process uses chemicals such as chromium compounds and produces liquid wastes that must be treated by physicochemical and biological systems. About 15,000 ton per month of dewatering sludge with 24% solids content is disposed of into landfills. During the process, pre-tanned skins (wet blue leather) are shaved to the desired thickness and the shavings, like sludge, are among the wastes that must have special attention. The organic content and chromium concentration are high. About 12% of the leather production from cattle hides are shavings, and its chromium concentration ranges from 3.5 to 5.5% of dry matter. The Environmentally friendly leather project, a co-operation between Brazilian and German tanneries, universities and technical schools, is looking for process optimisation, waste minimisation and adequate treatment for solid and liquid wastes from the leather industry. This work presents results of Low Temperature Conversion of chromecontaining sludge and shavings in a laboratory batch reactor, offering a solution for these hazardous wastes, recovering the energy content and transforming metals in insoluble sulphides. [ABSTRACT FROM AUTHOR]

In this work the parameters of Low Temperature Conversion--LTC were applied in a centrifuged sludge from a sewage treatment plant located in Rio de Janeiro, Brazil. Before the conversion, the sludge was dried and analyzed by TGA to observe its behavior with increasing temperature. The chemical composition of the crude pyrolysis oil was analyzed by FTIR, 1H NMR and GC-MS. The results showed that the oil is a mixture of hydrocarbons, oxygenated and nitrogenated compounds. Using a catalytic treatment it was possible to fractionate the oil where the predominant constituents were hydrocarbons showing that the cracking was effective. An important result was the difference between the calorific value of dry sludge (10 MJ kg(-1)), the pyrolysis oil (36 MJ kg(-1)) and one of the fractions separated by catalytic cracking (40 MJ kg(-1)) when compared with commercial diesel (45 MJ kg(-1))., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In this work low temperature conversion (LTC) process was applied in a dried sludge from a petrochemical industry wastewater treatment station located in Rio de Janeiro, Brazil. The process was performed in two modes: continuous and batch-scale. This process produced a pyrolysis oil (continuous 14%; batch-scale 40% yield); pyrolytic char (continuous 46%; batch-scale 56% yield); gas and water. Pyrolysis oil fraction was analyzed by gas chromatographic mass spectrometry (GCMS) and the main components identified were toluene, ethylbenzene, styrene, isopropyl benzene, alpha-methylstyrene, butanenitrile and 1,3- biphenyl propane. Metals content, sulfur content and calorific value have been determined for the pyrolysis oil fraction. The results showed that the pyrolysis oil obtained could be used for industrial purposes and/or as energetic matrix.