Abstract

NAVA URREGO, Lizet Marina; GASPERIN SANCHEZ, Raquel  and  DURAN MORENO, Alfonso. Biodegradation of toxic compounds from oil refinery wastewater: comparison of two batch reactors with suspended and attached biomass. Rev. Int. Contam. Ambient [online]. 2014, vol.30, n.1, pp.101-112. ISSN 0188-4999.

This study deals with the treatment of an oil refinery's wastewater using two sequencing batch reactors. The first one was a suspended biomass reactor and the second was an attached biomass reactor with Kaldnes K1 carriers. Due to the diversity and complexity of the refinery wastewater, it was necessary to acclimate the microorganisms using fixed efficiency strategy to ensure a good degradation of the poorly biodegradable or recalcitrant compounds. The reactor operated for 45 days using 24 h cycles (filling, reaction time, settle, draw and idle). The volumetric organic loading applied to both reactors ranged between 0.44 and 0.54 kg COD/m³d; the surface loads ranged between 1.56 - 1.80 g COD/m² d for the attached biomass reactor. The performance of the sequencing batch reactors was assessed by the efficiency of COD removal, DOC and phenols content, obtaining final removal percentages of75, 73 and 99 % in the suspended biomass reactor, while the attached biomass reactor reached removal percentages of 77, 81 and 99 %, respectively. The total suspended solids concentration in the reactor suspended biomass was approximately 2200 mg TSS/L while in the attached biomass reactor was between 450 and SST 560 mg/L. The VSS/TSS ratio was 0.8 and 1 for both reactors. The concentrations of biomass attached ranging from 3.98 g/m² to 5.45 g/m². In each reactor were made four profiles for assessing the ability of microorganisms to degrade type substrate to which they were exposed in a given time. In both reactors, degradation profiles 1 and 2 showed that a high COD removal occurred during the first hour of reaction, while for the sections 3 and 4 the maximum amount was reached after the second hour. In the case of total phenols, in all the profiles it was obtained a removal efficiency of over 98 % during the first hour of reaction, indicating that in both reactors, the biomass was able to degrade toxic compounds present in sour stripped water no matter what type of agglomeration microbial was used.

Keywords : sour water; phenols; inhibition; SBR.

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