Avaliação do tratamento da borra oleosa de petróleo após estabilização e monitoramento do material numa célula de aterro sanitário industrial experimental.

Abstract

The oily sludge of petroleum is one of residues produced for the exploitation and production of petroleum that requires a proper disposal, because it has a variety of contaminants, as heavy metals and oils and grease. In this context, the following work aimed to evaluate the disposal of oily sludge of petroleum, which has heavy metals and oils and greases, inside of a cell of industrial landfill in experimental scale after the stabilization using bentonite clay. The classification and chemical characterization of oily sludge of petroleum were made in the first stage of the work, in order to identifying elements that give it dangerousness. The oily sludge of petroleum kept a concentration of 8,27 mg.L"1 of chrome, above of Maximum Allowable Limit value which is 5 mg.L"1, therefore, the oily sludge is characterized as toxic and it can be classified as Grade I residue (dangerous). The content of oils and greases was of 46 mg.L"1, exceeding the limit of 20 mg.L"1 established by CONAMA Resolution n° 430/2011 for effluents from any pollution source. Preliminary tests were made in the second stage of work to justify the choice of configuration of experimental cell of industrial landfill, which were supported in the monitoring of four cells, varying the cover layers and the shape of disposal of residue. Precipitations were simulated during the monitoring of cells, and the produced leachate was analysed periodically. All test cells reduced, significantly, concentrations of metals and oils and greases to available level, especially those which had clay layer. In the last stage of work, before the mounting of cell of industrial landfill, the residue was subjected to the stabilization process using bentonite clay and placed into landfill cell with layer of sand and gravel. The cell was monitored during 75 days and the leachate was analysed periodically. At the final of monitoring, the concentration of oils and greases declined for 7,10 mg.L"1 and the chromium metal, which was in greater concentration, reduced for 0,12 mg.L"1. Results of analyse of leachates indicate that the oily sludge of petroleum is in decomposition stage of organic matter. The balance of mass was made to evaluate the stabilization of oily sludge of petroleum with bentonite clay and it showed that, O&G contaminants, total chromium and total lead, were reduced in 44,2%, 44,4% e 25,0%, respectively. The efficiency of retention of contaminants was significant, especially for DQO, chromium and O&G, whose values were 49,12%, 44,40% e 44,20%, respectively. The greater speeds of biostabilization were for DQO, chromium and O&G, in other words, 0,00867, 0,00754 e 0,00745 d"1, respectively. At the final of research, it is possible to conclude that with the stabilization of oily sludge of petroleum into clay mass and the disposition of this material into experimental cell of industrial landfill, it obtained a non-hazardous material (Grade II) and contaminants that there were into oily sludge of petroleum were attenuated.