# Pharmaceuticals Removal from Wastewater with Microalgae: A Pilot Study
###### Abstract  
Urban wastewaters contain pharmaceuticals that are not appropriately removed in conventional wastewater treatments, limiting treated water reuse. Microalgae have been shown to remove pharmaceuticals from urban wastewater in laboratory trials, but few studies have been conducted under natural conditions. In this work, pharmaceutical removal was assessed in a pilot-scale microalgal tertiary wastewater treatment in real conditions. Even after secondary treatment, the water contained measurable amounts of pharmaceuticals (an average of 218.4 ng/L) that significantly decreased to 39.83 ng/L at the exit of the microalgal system. Pharmaceuticals' average removal rates were slightly higher in the summer (79.1%) than in autumn (71.1%). Antibiotics and antipsychotics were better removed (88.8 and 86.4%, respectively) than antihypertenisves (75.3%) and others (Bezafibrate and Diclofenac; 64.0%). Physicochemical characteristics of the wastewater influenced pharmaceutical removal; significant positive correlations were observed between anti-hypertensive drug removal and ammonium concentration (\(r=0.53\); \(p<0.05\)), total nitrogen and total pharmaceutical removal (\(r=0.46\); \(p<0.05\)), and total nitrogen and antipsychotic drug removal (\(r=0.47\); \(p<0.05\)). The results demonstrate the effectiveness of microalgal tertiary treatment in the removal of pharmaceuticals. microalgae; wastewater treatment plant; pharmaceuticals; environment contaminants +
Footnote †: journal: _Sciences_  
0000-0002-0001-999X/0000  
for pharmaceutical removal from wastewater, being the biological treatment the most studied and used [3; 4; 5]. However, as wastewater treatment plants (WWTPs) were not designed to eliminate persistent pharmaceutical compounds, they are not able to completely remove the pharmaceuticals and their metabolites [2; 6]. Therefore, these compounds are disseminated into aquatic compartments via treated effluent discharges and land application of biosolids [7]. Their potential for negative ecotoxicological effects, even at sublethal concentrations, in the aquatic environment has been of concern [8; 9]. Risk has been observed in all aquatic compartments, evidencing the importance of mitigation measurements [7]. Moreover, its presence in treated water can also hinder its reuse [10]. Considering that around 50% of the population in the Mediterranean experiences water stress in the summer, wastewater reuse would help the EU to achieve Sustainable Development Goal 6, related to the availability and sustainable management of water [11]. In this line of thought, wastewater treatment using microalgae can strongly contribute to the sustainable reuse of wastewater. Microalgae are unicellular or colonial photoautotrophic microorganisms that grow using solar energy, CO\({}_{2}\), and nitrogen and phosphorus, which are nutrients abundantly found in wastewater. They are also able to remove most of the organic (e.g., pharmaceuticals and personal care products, pesticides, and aromatic hydrocarbons) and inorganic pollutants (e.g., nitrogen, phosphorus, and metals) from these waters. Often growing in mixotrophic systems, together with bacteria, microalgae have been successfully used for the bioremediation of nutrients, such as nitrogen, phosphorus, and carbon from municipal wastewater [12]. In microalgae-based treatment systems, coupling nutrient removal with emerging contaminant bioremediation further improves the cost-efficiency of wastewater treatment [12; 13]. This produces cleaner treated water than most conventional wastewater treatment systems, warranting water reuse [14]. Being photosynthetic, microalgae systems rely on solar energy and consume much less energy than bacterial-based systems, which, together with the fact that they consume rather than emit CO\({}_{2}\), makes their life-cycle assessment more favorable than the bacterial-based ones [15].