Valorization of Microalgae Biomass by Its Use for the Removal of Paracetamol from Contaminated Water

Carla Escapa,Samuel Vega,Cristina Nuevo,Luis Calvo,Ricardo Coimbra,Marta Otero,Ana García,Sergio Paniagua

doi:10.3390/w9050312

Abstract

Microalgae are aquatic photosynthetic prokaryotic or eukaryotic microorganisms which cultivation for the fixation of CO2 and the production of biofuels has received large attention. However, the sustainable development of an algal biorefinery is still a challenge. In this context, the valorization of microalgae biomass for a wastewater adsorptive treatment may be an option to explore. Recently, the presence of emerging contaminants (ECs) in natural waters and the associated risks have led to a great concern, especially in the case of pharmaceuticals. In the present work, the elimination of paracetamol from water by biosorption onto microalgae, namely Synechocystis sp., has been studied. Kinetic and equilibrium parameters have been determined and compared with those obtained when using a commercial activated carbon under the same experimental conditions. Although the adsorption kinetics are very similar onto both materials, at the equilibrium, the Langmuir maximum capacity of the activated carbon (278 mg g−1) is five times higher than that of Synechocystis sp. (53 mg g−1). In any case, it must be considered that the utilization of microalgae may be considered an environmentally friendly process with important associated savings.

Highlights

The worldwide energy crisis and global warming have both caused an increase in the research on the production of renewable energies [1]
The amount of adsorbed paracetamol increased with time until becoming stable at the equilibrium, which happened after stirring for 240 min
The kinetic experimental results have been properly described by the Lagergren and the pseudo second kinetic equations, and the equilibrium time was 240 min for both adsorbent materials

Summary

Introduction

The worldwide energy crisis and global warming have both caused an increase in the research on the production of renewable energies [1]. The Kyoto Protocol committed the signatory countries to reduce the emission of greenhouse gases, so the production of third generation biofuels from photosynthetic microorganisms, such as microalgae and cyanobacteria, has stirred up considerable attention due to their CO2 fixation capacity [2,3]. Only 5 kt/year of microalgal biomass are produced with production costs of. 18.527 €/t [4], a reduction up to 296 €/t being needed to reach a competitive price in the biofuels market [5]. To substitute the consumption of biofuels in Europe by microalgal biodiesel, 9.25 millions of hectares (approximately the surface of Portugal) with a productivity of. Huge amounts of phosphorus and nitrogen are necessary for the culture of microalga, which reduces the sustainability of the process because of both their high price as a pure chemical product and their availability [7].

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Conclusion