Abstract
The purpose of this study was to investigate whether pharmaceutical pollutants in urban wastewater can be reduced during algal cultivation. A mixed population of wild freshwater green algal species was grown on urban wastewater influent in a 650 L photobioreactor under natural light and with the addition of flue gases. Removal efficiencies were very high (>90 %), moderate (50–90 %), low (10–50 %), and very low or non-quantifiable (<10 %) for 9, 14, 11, and 18 pharmaceuticals, respectively, over a 7-day period. High reduction was found in the following pharmaceuticals: the beta-blockers atenolol, bispropol, and metoprolol; the antibiotic clarithromycine; the antidepressant bupropion; the muscle relaxant atracurium; hypertension drugs diltiazem and terbutaline used to relive the symptoms of asthma. Regression analysis did not detect any relationship between the reduction in pharmaceutical contents and light intensity reaching the water surface of the algal culture. However, the reduction was positively correlated with light intensity inside the culture and stronger when data collected during the night were excluded. Algae cultivation can remove partially or totally pharmaceutical pollutants from urban wastewater, and this opens up new possibilities for treating urban wastewater.
Highlights
Environmental pollution due to excessive releases of nutrients and other chemicals in urban wastewater is increasingly recognized as a major threat to aquatic ecosystems globally
Dictyosphaerium, the most frequent alga found in the present study, was among the dominant algae species in a wastewater treatment study performed in New Zealand (Park et al 2011b)
This could complicate harvesting by sedimentation, since Dictyosphaerium can remain suspended for a long time (Park et al 2011b)
Summary
Environmental pollution due to excessive releases of nutrients and other chemicals in urban wastewater is increasingly recognized as a major threat to aquatic ecosystems globally. A strategy that could counter this threat is to use algal ponds or bioreactors. This approach is not new (Oswald and Gotaas 1957). It has recently attracted the interest of many scientists around the world, mainly due to the ability of algae to take up nutrients and remove pollutants from wastewater efficiently (Hoffman 1998; Sturm and Lamer 2011), and the possibility of producing high-energy biomass from them (Rawat et al 2011; Park et al 2011a). García et al (2006) found that total nitrogen and phosphorus contents in municipal wastewater can be reduced by 73 and 43 %, respectively, by using mini high-rate algal ponds in Spain, and in other cases, reductions of 90–95 % have been reported (Hoffman 1998; Ruiz-Marin et al 2010). Algae have been grown on other types of wastewater such as fish and animal production waste streams (Woertz et al 2009; Riaño et al 2011)
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