Removal of pharmaceutical compounds (ranitidine, tramadol, and gabapentin) from wastewater by Trichormus variabilis microalgae

Abstract

AbstractWastewater effluent from the pharmaceutical, cosmetic, and chemical industries often contains pharmaceutical contaminants, making the reuse of wastewater a controversial practice. Physical and chemical methods have been unsuccessful in removing these pollutants on a large scale. Microalgal technology has been introduced as a promising tool to tackle this issue. This study evaluated the performance of Trichormus variabilis microalgae in removing three contaminants, namely ranitidine, tramadol, and gabapentin. Three concentrations of each compound were introduced into the microalgal culture medium. The effect of these pharmaceutical concentrations on growth, biomass production, photosynthetic pigments, and protein and lipid content was evaluated and compared with control cultures over 14 days. It was found that T. variabilis was able to remove 61–100% of these drugs. Moreover, the addition of 250 mg L–1 of ranitidine to the algae culture medium led to a 33.4% reduction in biomass growth. Adding 20 mg L–1 of tramadol and 200 mg L–1 of gabapentin caused 30% and 19.2% biomass reductions, respectively. The presence of 100 mg L–1 of gabapentin led to a 38% and up to 14% increase in chlorophyll and carotenoid content in comparison with the control, while the presence of the other drugs reduced the content of chlorophyll and carotenoid. On the other hand, the protein content increased by 254% in the culture media compared to the control media in the presence of 50 mg L–1 ranitidine. Regarding lipid concentration, 20 mg L–1 of tramadol had the most important effect by doubling the lipid content in T. variabilis in comparison with the control. In conclusion, these drugs could be removed to a significant extent by T. variabilis, which is promising for larger scale applications.