Treatment of pharmaceutical industrial wastewater by nano-catalyzed ozonation in a semi-batch reactor for improved biodegradability

Abstract The study reports the biodegradability enhancement of pharmaceutical wastewater along with COD (Chemical Oxygen Demand) color and toxicity removal via O3, O3/Fe2+, O3/nZVI (nano zero valent iron) processes. Nano catalytic ozonation process (O3/nZVI) showed the highest biodegradability (BI = BOD5/COD) enhancement of pharmaceutical wastewater up to 0.63 from 0.18 of control with a COD, color and toxicity removal of 62.3%, 93% and 82% respectively. The disappearance of the corresponding Fourier transform infrared (FTIR) and gas chromatography–mass spectrometry (GC–MS) peaks after pretreatment indicated the degradation or transformation of the refractory organic compounds to more biodegradable organic compounds. The subsequent aerobic degradation study of pretreated pharmaceutical wastewater resulted in biodegradation rate enhancement of 5.31, 2.97, and 1.22 times for O3/nZVI O3/Fe2+ and O3 processes respectively. Seed germination test using spinach (Spinacia oleracea) seeds established the toxicity removal of pretreated pharmaceutical wastewater.