Ti O IND.2 heterogeneous photocatalysis in secondary wastewater treatment / Fotocatálise heterogênea com Ti O IND.2 aplicada ao tratamento de esgoto sanitário secundário




The heterogeneous photocatalysis with Ti O IND.2 and solar radiation in secondary wastewater treatment to remove organic matter and microorganisms was investigated. A glass plate (approximate 0.48 M POT.2 ) with immobilized titanium dioxide (10 g/ M POT.2 ) was operated in different flow rates (15; 22.5 and 30 L/h) and angles in relation to horizontal (2, 12 and 22 degrees). Two effluents were used in the assays. The first (effluent 1) was from an anaerobic reactor treating sewage and the second (effluent 2) from an anaerobic/aerobic granular activated carbon expanded bed reactor which receives the wastewater collected in the Campus of USP/São Carlos and from the surrounding neighborhood of the campus. The assays were carried out in batch with recirculation time of 4 hours. The photolysis (only solar radiation) and the catalyst adsorption (Ti O IND.2 in the dark) in organic matter removal and disinfection were evaluated. The oxidation of organic matter (COD and TOC) and inactivation of indicators of fecal contamination (Clostridium perfringens, total coliforms, E. coli, and coliphages) were evaluated. The results shows that heterogeneous photocatalysis was more efficient in effluents disinfection than the photolysis. The resistance of the microorganisms to Ti O IND.2 /UV process was in decreasing order: Clostridium perfringens, total coliforms, E. coli and coliphages. The best operational conditions for microorganisms inactivation in effluent 1 are: alfa = 2 degrees and Q = 22.5 L/h. TOC oxidation in effluent 2 was more influenced by angle than by flow rate. The physical and chemical characteristics of the effluents had an important role in oxidation and disinfection. Initial E. coli concentration was more important than intensity of solar radiation during photocatalytic disinfection in the experimental conditions of this work. The reactors with immobilized Ti O IND.2 open to solar radiation have to be closed to avoid excessive evaporation


radiação solar disinfection wastewater treatment desinfecção fotocatálise heterogênea titanium dioxide solar radiation dióxido de titânio tratamento de esgoto heterogeneous photocatalysis

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