Advanced oxidative process for treating the effluents from the bleached kraft cellulose industry / Processos oxidativos avançados para tratamento de efluentes de indústria de celulose kraft branqueada

AUTOR(ES)

Teresa Cristina Fonseca da Silva

DATA DE PUBLICAÇÃO

2007

RESUMO

In this work, the processes photo-Fenton, H2O2/UV, TiO2/UV and H2O2/TiO2/UV were compared and optimized in order to obtain organic matter removals from the effluents of the bleached kraft cellulose industry. Those processes were applied before and after the biological treatment of the effluents. Initially, the best pH conditions for application of the processes were studied. For the experiments combining the use of the reagents, such as the photo-Fenton and H2O2/TiO2/UV processes, a response surface was constructed in order to obtain the best proportions among the concentrations of the reagents inside and outside experimental space. The efficiency of those processes were monitored by the analyses of DQO, color and COT. For the effluent collected before the biological treatment, DBO5 analyses were performed in the most efficient experimental point (s) reached by the Advanced Oxidative Processes (POAs) for verifying the possible biological treatability (relationship DBO5/DQO) in those effluents. The treatments showed that the optimum pH for treatment of the effluents was 3.0 for the processes photo-Fenton, H2O2/UV and H2O2/TiO2/UV and 8.0 for the treatment TiO2/UV. However, the pH 8.0 was chosen for all treatments, except for the photo-Fenton treatment, from which the pH was 3.0. Among the processes under study, the one from which the experiment showed higher removal of DQO and COT was the photo-Fenton treatment, from which the concentrations of H2O2 and Fe2+were 700: 3.8 (mg L-1). The process H2O2/UV showed high percent removal of DQO, color and COT for those experiments using H2O2 concentrations at 500 mg L-1. The heterogeneous photocatalysis (TiO2/UV) was the treatment causing the lowest reduction of the organic matter, even when high concentrations of TiO2 (1000 mg L-1) were used. The treatment that combines the heterogeneous photocatalysis with hydrogen peroxide (H2O2/TiO2/UV) can be considered as advantageous in relation to H2O2/UV process, when low H2O2 amounts are used. No increase was found for biological treatability, after the accomplishment of the advanced oxidative processes. In addition, the treatments were less efficient for the effluent collected before the biological treatment than for the effluent collected after this treatment. As tertiary treatment, the advanced oxidative processes using high H2O2 concentrations reached DQO removals at the range from 60 to 70% removal, 100% removal of the color, whereas the removal values reached the range from 70 to 90% for COT.

ASSUNTO(S)

optimization advanced oxidative process tratamento de efluentes processos oxidativos avançados treating the effluents quimica analitica otimização

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