RESUMO
Conventional sewage treatment systems are generally not designed to remove micropollutants, requiring the development of new technologies, such as the combination of biological processes with advanced oxidative processes. The configuration of an anaerobic expanded granular sludge bed (EGSB) reactor stands out for its use of granular biomass and high sludge bed expansion. Ozonation is an advanced oxidative process that stands out as one of the most promising technologies for the degradation of micropollutants. Thus, the present work aimed to evaluate the removal of drugs through the application of ozonation as a polishing process for the effluent of an EGSB reactor that was fed with synthetic sewage. Ozonation was shown to be efficient in the degradation of these compounds, reaching removals above 90%. It was found that the degradation profile of each drug varied according to its chemical structure since some drugs are more susceptible to oxidation than others and since the concentrations of pharmaceuticals are also related to their removal. Moreover, the assessment of risks to the environment and human health confirmed the need to assess the best scenario for risk reduction considering all drugs, since even with almost complete removal of some compounds, the effluents still showed toxicity. Thus, the high removal efficiencies found for the evaluated micropollutants showed that this technique has the potential to be used to improve the quality of biological reactor effluents or even to be combined in effluent reuse systems.
Assuntos
Ozônio , Esgotos , Anaerobiose , Reatores Biológicos , Humanos , Oxirredução , Eliminação de Resíduos LíquidosRESUMO
Direct (UV) and hydrogen peroxide-assisted (UV/H2O2) photolysis were investigated in bench-scale for removing the organic compounds present in the electrodialysis reversal (EDR) brine from a refinery wastewater reclamation plant. In the UV/H2O2 experiments, a COD:H2O2 molar ratios of 1:1, 1:2 and 1:3 were tested by recirculating the brine in the UV reactor for 120 min. Results showed a significant reduction in UVA254, whereas no reduction was observed for chemical oxygen demand (COD), in the UV process, suggesting great cleavage but limited mineralization of the organic matter. UV/H2O2 with C:H2O2 ratio of 1:3 exhibited high efficiency in removing the organic matter (COD removal of 92% with an electrical energy per removal order (EEO) value of 22 kW h m-3). Although the EDR brine has high salinity, no strong scavenging effect of â¢OH was found in the water matrix due to the high concentration of anions, especially chloride and bicarbonate. Finally, UV/H2O2 with C:H2O2 ratio of 1:3 and residence time of 120 min is an efficient alternative for organic matter removal of EDR brine from refinery wastewater reclamation plant showing total capital cost (CapEx) estimated at US$ 369,653.00 and total operational cost (OpEx), at US$ 1.772 per cubic meter of effluent.
Assuntos
Peróxido de Hidrogênio/química , Compostos Orgânicos/isolamento & purificação , Petróleo , Sais/isolamento & purificação , Raios Ultravioleta , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Conservação dos Recursos Hídricos/métodos , Filtração/métodos , Humanos , Peróxido de Hidrogênio/farmacologia , Indústria de Petróleo e Gás/métodos , Oxirredução , Petróleo/análise , Fotólise , Salinidade , Instalações de Eliminação de Resíduos , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiaçãoRESUMO
The purpose of this article is to evaluate the integration of the air stripping, membrane bioreactor (MBR) and nanofiltration (NF) processes for the treatment of landfill leachate (LFL). Pretreatment by air stripping, without adjustment of pH, removed 65% of N-NH3 present in LFL. After pretreatment, the effluent was treated in MBR obtaining 44% of COD removal, and part of the N-NH3 was converted to nitrite and nitrate, which was later removed in the post-treatment. Nanofiltration was shown to be an effective process to improve the removal of organic compounds, the high toxicity present in LFL and nitrite and nitrate generated in the MBR. The system (air stripping + MBR + nanofiltration) obtained great efficiency of removal in most parameters analyzed, with overall removal of COD, ammonia, color and toxicity approximately 88, 95, 100 and 100%, respectively. By this route, treated landfill leachate may be reused at the landfill as water for dust arrestment and also as earth work on construction sites.