Biological treatment of pharmaceutical wastewater from the antibiotics industry
Pharmaceutical wastewater generated by an antibiotics (penicillin) company was treated by aerobic membrane bioreactors (MBRs) and sequencing batch reactors (SBRs). At a low organic loading rate of 0.22 kg-COD m−3d−1, both types of reactors were capable of treating the wastewater such that the treated effluent met the discharge regulation except for the total dissolved solids. However, when the loading rate was increased to 2.92 kg-COD m−3d−1, foaming issues resulted in unstable performance. Overall, the MBRs achieved better solid removal but the SBRs performed better in regards to the degradation of aromatic compounds, as determined by UV absorbance (UVA). Finally, ozonation was applied on two different streams and showed promise on the strong stream – that corresponds to the formulation effluent and contains most of the biorefractory compounds. Ozonation successfully reduced the UVA, lowered the pH and increased the biochemical oxygen demand : chemical oxygen demand (BOD5 : COD) ratio of the strong stream. However, it was less efficient on the effluent having undergone pre-treatment by a biofilter due to a lack of selectivity towards refractory compounds.