Reclamation of pharmaceutical wastewater by UAF, contact oxidation, and auto brush-cleaning aiding nano ZrO₂ coated ceramic membrane MBR - an industrial-scale practice and functional microbial diversity

This project aimed to assess the feasibility of applying UAF/contact oxidation followed by ceramic membrane MBR in reclaiming 1400 m³/day of pharmaceutical wastewater with COD and NH₄⁺-N of around 8400 and 135 mg/L, respectively. UAF and contact oxidation system employed novel porous lightweight ceramsite as microbial carriers to facilitate the biomass retention. Results revealed that the integrated biological treatment experienced excellent and stable performance in the operation of successive 160 days in terms of COD and NH₄⁺-N abatement, around 96.8% and 81%, respectively. With the aid of auto mechanical bush and air scouring in submerged flat-sheet nano ZrO₂ coated ceramic membrane MBR for mitigating the membrane fouling, the MBR exhibited stable and better performance to remove suspended solid and soluble microbial products with around flux of 25 LMH and no severe fouling was observed during the whole treatment process. The MBR effluent can be reclaimed for road cleaning, urban landscaping, etc. Miseq sequencing analysis in the sludge-day 160 indicated that UAF was rich in Firmicutes with 42.02% relative abundance, followed by Thermotogae (22.91%) and Bacteroidetes (13.59%), which can decompose macromolecules into small molecules. Moreover, some species in Thermotogae and Bacteroidetes accounted for generation of biofilm in the ceramsite in UAF. Genus Petrotoga played a key role in conspicuous COD removal in UAF. The bacterial species composition in contact oxidation exhibited substantially discrepant. Appearance of Proteobacteria, as the dominant phylum (41.7%) can be responsible for COD abatement. Genus Thauera, Acinetobacter and Aeromonas detected had the capacity in NH₄⁺-N removal.