Remediation of a mixture of analgesics in a stirred-tank photobioreactor using microalgal-bacterial consortium coupled with attempt to valorise the harvested biomass.

An artificial microalgal-bacterial consortium was used to remediate a mixture of analgesics (ketoprofen, paracetamol and aspirin) in a stirred-tank photobioreactor. A hydraulic retention time (HRT) of 3days supported poor treatment because of the formation of p-aminophenol (paracetamol toxic metabolite). Increasing the HRT to 4days enhanced the bioremediation efficiency. After applying an acclimatization regime, 95% removal of the analgesics mixture, p-aminophenol and COD reduction were achieved. However, shortening the HRT again to 3days neither improved the COD reduction nor ketoprofen removal. Applying continuous illumination achieved the best analgesics removal results. The harvested biomass contained 50% protein, which included almost all essential amino acids. The detected fatty acid profile suggested the harvested biomass to be a good biodiesel-producing candidate. The water-extractable fraction possessed the highest phenolic content and antioxidant capacity. These findings suggest the whole process to be an integrated eco-friendly and cost-efficient strategy for remediating pharmaceutical wastewater.

Biodegradation of ketoprofen using a microalgal-bacterial consortium.

OBJECTIVE: To test the toxicity of ketoprofen (a commonly-used NSAIDs) using two microalgal strains and Artemia sp. following the isolation of bacterial and microalgal strains and testing their ability to biodegrade and tolerate ketoprofen. RESULTS: Chlorella sp. was the most resistant to ketoprofen. A defined bacterial consortium (K2) degraded 5 mM ketoprofen as a sole carbon source both in the dark or continuous illumination. Ketoprofen did not undergo photodegradation. In the dark, biodegradation was faster with a lag phase of 10 h, 41% COD removal and 82 % reduction in toxicity. The consortium degraded up to 16 mM ketoprofen. The consortium was composed of four bacterial isolates that were identified. MS/MS analysis suggested a ketoprofen biodegradation pathway that has not been previously reported. Combining Chlorella sp. and the K2 consortium, ketoprofen was degraded within 7 days under a diurnal cycle of 12 h light/12 h dark. CONCLUSION: The feasibility of using a microalgal-bacterial system to treat pharmaceutical wastewater is promising for the reduction of the process cost and providing a safer technology for pharmaceutical wastewater treatment.