The effect of caffeine, metronidazole, and ibuprofen on continuous flow activated sludge process

Yerkanat N. Kanafin, Yerbolat Kakimov, Assyl Adamov, Ardak Makhatova, Abilmansur Yeshmuratov, Stavros G. Poulopoulos, Vassilis J. Inglezakis, Elizabeth Arkhangelsky

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


The aim of this work was to study the biological treatment of a synthetic wastewater containing emerging contaminants. The 95‐day experiment was conducted in an 81 L continuous flow conventional activated sludge apparatus consisting of anoxic and aerobic reactors with internal recycling, and a clarifier with activated sludge recycling. Real activated sludge from the municipal wastewater treatment plant in the Nur‐Sultan city was used. The degradation efficiencies of caffeine, metronidazole, and ibuprofen in the synthetic wastewater were studied either separately or in combination.

When treated separately at the concentration of 30 mg/L, the degradation of caffeine and ibuprofen was up to 100%, while the degradation of metronidazole was in the range of 12–27%. Caffeine and ibuprofen inhibited the nitrification process, while the presence of metronidazole in the system suppressed the activity of denitrifying microorganisms. The biological treatment of the synthetic wastewater containing all three compounds (at the concentration of 10 mg/L each) resulted in degradation of caffeine and ibuprofen up to 100%, and 56% in the case of metronidazole. As both nitrification and denitrification processes were affected, the total nitrogen removal was significantly reduced from 53% to 22%.

Complete degradation of caffeine and ibuprofen, and partial degradation of metronidazole were observed in a synthetic wastewater using the activated sludge process. As the presence of emerging pollutants in a wastewater affects the general efficiency of the wastewater treatment plants, other physical or chemical pre‐treatment should be utilized to minimize the harmful effect of contaminants on the biological processes.
Original languageEnglish
Pages (from-to)1370-1380
Number of pages11
JournalJournal of Chemical Technology and Biotechnology
Issue number5
Publication statusPublished - May 2021


  • activated sludge
  • caffeine
  • emerging pollutants
  • ibuprofen
  • metronidazole
  • pharmaceuticals
  • wastewater

ASJC Scopus subject areas

  • Biotechnology
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Waste Management and Disposal
  • Pollution
  • Organic Chemistry
  • Inorganic Chemistry


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