Biological treatment performance of hypersaline wastewaters with high phenols concentration from table olive packaging industry using sequencing batch reactors

Abstract

Biological treatment of hypersaline wastewaters such as fermentation brine from table olive processing (FTOP), was carried out using four sequential biological reactors (SBRs). These wastewaters were characterized by conductivities higher than 90mScm−1 together with COD and total phenols concentration values of more than 15gL−1 and 1000mgL−1, respectively. In order to increase the organic removal efficiency and to reduce the hydraulic retention time (HRT), extra nutrients were added and pre-treatment by adsorption was performed. Results showed that the COD/N/P relationship, in the FTOP, of 250/5/1 was appropriate for the biological process reaching COD removal efficiencies of around 80%. The FTOP adsorption pre-treatment with powder activated carbon for the reduction of phenols concentration to 400mgL−1 led to a HRT reduction from 40 to 15 days, maintaining the COD and total phenols removal percentages around 78% and 97%, respectively. On the other hand, γ-Proteobacteria was the main bacterial class, representing around 74% of the microbial community in the reactors.