Effects of selected pharmaceuticals on nitrogen and phosphorus removal bioprocesses

• The anoxic P uptake via nitrite was more tolerant to PhaCs than the aerobic one.
• IBUP was the most toxic single tested compound to nitrogen removal via nitrite.
• Denitritation and aerobic P uptake were the most sensitive processes.

The inhibitory effect of five selected pharmaceuticals on the nitrogen and phosphorus removal bioprocesses was investigated with emphasis on the via nitrite removal pathway. Biomass was collected from a sequencing batch reactor (SBR) and was spiked with specific pharmaceutical concentrations (10–500 mg L−1). Batch activity tests were conducted to determine the level of inhibition caused by the selected pharmaceuticals and their combinations to the rate of nitritation, denitritation, phosphorus uptake via nitrite and via oxygen and phosphorus release. The highest inhibition of nitritation was observed when 250 mg L−1 of ibuprofen mg L−1 and 250 of paracetamol were added. Out of the 12 different combination that were tested, sPRR was the bioprocess that was least inhibited by the pharmaceuticals in 4 cases (p < 0.05), while the aerobic phosphorus uptake was the most severely inhibited bioprocess in 4 cases (p < 0.05).In most cases, anoxic phosphorus uptake via nitrite was more tolerant compared to aerobic phosphorus uptake. Thus, its implementation is more favorable for the treatment of effluents with high pharmaceutical concentrations.

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