Remoção de fenol de efluente sintético com biofilme suportado em carvão ativado: estudo em batelada e em leito fixo

Abstract

Biological degradation through supported biofilm is a good method to minimize the toxic properties of contaminants, where wastewater regeneration occurs through biodegradation processes by microorganisms, which transform contaminants into simpler compounds. Thus, the use of biofilms supported on particulate inert materials allows, among others, a higher concentration of retained biomass and an increase in metabolic activity, with a greater efficiency of removal of contaminants such as phenol. The objective of this work was to evaluate the biodegradation of phenol using biofilm supported on charcoal in batch reactor and fixed bed column. The biodegradation of phenol in a batch reactor was performed using the charcoal containing the biofilm developed in different systems: orbital agitation bioreactor (OAB); and mechanical agitation bioreactor (MAB). The phenol concentrations evaluated were: 150, 100 and 50 mg L-1, initial pH in the range of 6.0 - 7.0 at room temperature. The results showed that the MAB bioreactor presented better performance in the removal of phenol and COD, due to the higher amount of biomass adhered to the support (8.56 mg support-1), reaching approximately 100% phenol biodegradation in 300 min. (3.47 mgsupport-1), the maximum removal at the three concentrations was obtained in approximately 720 minutes. The toxicity analyzes in the wastewater treated in the batch system showed moderate toxicity, and that the biodegradation process can be used as an alternative to remove this contaminant and the subsequent release of the effluent into the environment. In the fixed bed column studies, three different flow rates (2, 3 and 4 mL min.-1) and phenol concentrations (150, 100 and 50 mg L-1) were studied. In these tests the microorganisms adapted in the supports OAB and MAB of the batch bioreactors were used. The results of the column tests showed a better removal for the MAB bioreactor (which presented higher amount of biomass adhered) for the lower flows studied. The lower flow rate presents a longer residence time of the phenol within the column in contact with the microorganisms, consequently increasing the efficiency of biodegradation. It was also carried out the characterization of the substrates containing the biofilm in terms of its morphology through scanning electron microscopy (SEM), as well as microbiological analysis, in order to identify the microbial genera present in the biofilm of the bioreactors. The SEM analyzes showed visible morphological changes in the coals containing the biofilm, being these more accentuated in the support from the MAB bioreactor. The microbial analyzes of the supported biofilms indicated the presence of different microbial genera such as fungi, Penicillium spp., Fusarium spp., Trichoderma spp., Cladosporium spp., Rhizopus spp. and bacteria. Through this study, it was possible to verify the efficiency of the use of biofilms supported in the removal of toxic contaminants such as phenol, both in batch and continuous flow, as well as the biofilm formation process (OAB and / or MAB) interferes directly on the quality of the coating of the support, consequently on the performance of the material containing the biofilm used in the removal of the phenol.