Tratabilidade de águas residuárias contendo poluentes perigosos: estudo de caso.

Autor: Morita, Dione Mari
Jazyk: portugalština
Rok vydání: 1993
Předmět:
Druh dokumentu: Tese de Doutorado
Popis: O trabalho foi desenvolvido com o objetivo de caracterizar e estudar formas de tratamento de águas residuárias de indústrias de refino de óleo lubrificante e de recuperação de solventes. A fase preliminar teve por objetivo avaliar a biodegradabilidade do despejo combinado dessas duas indústrias. A segunda foi realizada em instalação piloto composta, basicamente, de uma unidade de arraste com ar/tanque de equalização, tanques de correção de pH e de aeração com tempos de detenção distintos, seguidos de tanques de sedimentação. Foram executados testes para avaliar a remoção de material solúvel em n-hexano do despejo da indústria de refino de óleo lubrificante e do efluente final. A unidade de arraste com ar difuso operando com subpressão de 15 mmhg a saída dos gases, vazão específica de ar de 20 ml/l min. E tempo de detenção de 5 dias foi eficiente na remoção de acetona, piridina, benzeno, tolueno, hexano, metil etil cetona e provavelmente solventes clorados. Não apresentou remoção significativa de álcoois, que foram eficientemente degradados no sistema biológico subsequente. Obteve-se remoções superiores a 90%, em termos de dbo e dqo, no processo biológico com tempos de detenção de 20 e 30 dias, e em torno de 80% para os demais. Os sistemas biológicos responderam bem as cargas transientes de solventes, exceto para o tolueno e o álcool isopropílico.
Traditionally, raw materials from solvent recovery and from reclaimed lubricating oil industries are considered hazardous solid waste. Consequently, the best control technology is incineration. This work was developed in order to characterize and to study ways of treating wastewaters from lubricating oil refinery and solvent recovery industries. The experimental part was divided in two phases. The preliminar step aimed to evaluate the biodegradability of combined wastewater from both industries. The second phase was basically carried out in a pilot plant composed by an air stripping unit/equalization tank, pH correction tanks and bioreactors with different retention times, followed by sedimentation tanks. Other than these assays, tests were performed to evaluate the removal of soluble material in n-hexane of the wastewater of the lubricating oil refinery industry and of the supernatant of the sedimentation tank after the bioreactor of 20 days retention.The buble aeration unit operating with a 15 mmHg suppresion to the gas exit, with a specific air flow of 20 mL/L.min. and with a retention time of 5 days was efficient to remove acetone, pyridine, benzene, toluene, hexane, methyl ethyl ketone and probably chlorinated solvents. There was no significative removal of alcohols, that were efficiently degraded in the subsequent biological system. BOD and COD removal efficiencies were better than 90% in the biological process with retention times of 20 and 30 days, and about 80% for the rest. The responses of biological systems to the transient inputs of solvents were well, except for toluene and isopropilic alcohol. Several physico-chemical processes for soluble material in n-hexane removal were studied. The only one to present effluent concentration under the legal limit was the addition of the sodium xylene-sulphonate base demulsifier to the supernatant of the sedimentation tank the bioreactor of 20 days retention.
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