Capacity of simultaneous removal of zinc and cadmium from contaminated media, by two microalgae isolated from a polluted site

Abstract

Several aquatic environments have been contaminated with heavy metals dumped via industrial effluents. Numerous studies have been published regarding the removal of single metals from aqueous solutions by microalgal biomass. However, such studies do not reflect the actual problem associated with industrial effluents because usually more than one metal species is present. Here we studied the biosorption capacity of Zn 2? and Cd 2? as single-and binarymetal systems by two microalgae, Scenedesmus obliquus and Desmodesmus pleiomorphus, isolated from a polluted site in Northern Portugal. For each metal independently, D. pleiomorphus showed a higher metal sorption capacity than S. obliquus, at concentrations ranging from 60 to 300 mg/l (except 150 mg Cd /l). Maximum amounts of Zn 2? and Cd 2? removed were 22.3 and 60.8 mg/g by S. obliquus, and 83.1 and 58.6 mg/g by D. pleiomorphus. In binary-metal solutions, S. obliquus was in general able to remove Zn 2? to higher extents than Cd 2? , whereas the opposite was observed with D. pleiomorphus. The simultaneous uptake of Zn 2? and Cd 2? by both microalgae was considerably lower than that of their single-metal counterparts, at equivalent concentrations. Although microalgal uptake from binary-metal solutions was lower than from single-metal ones, the wild microalgae selected were able to efficiently take up mixtures of Zn 2? and Cd 2? up to 300 mg/l of both metals-thus materializing a promising bioremediation vector for polluted waters.

A multilevel sustainability analysis of zinc recovery from wastes

“…Microalgae have versatile roles in CO 2 sequestration, biofuel production and wastewater treatment, which are crucial in mitigating various environmental impacts . A few recent examples of the employment of microalgae in removing zinc from wastewater are presented in Table 4 (Chan et al, 2014;Monteiro et al, 2011;Gvç lv and Ertan, 2012;Ji et al, 2012;Singh et al, 2007). Biomass is also efficient in removing zinc and other metals from wastewater.…”

“…Heavy metals including zinc can also be removed from wastewater through biosorption process using microalgae (Suresh Kumar et al, 2015;Chan et al, 2014;Monteiro et al, 2011;Gvç lv and Ertan, 2012;Ji et al, 2012;Singh et al, 2007). Microalgae have versatile roles in CO 2 sequestration, biofuel production and wastewater treatment, which are crucial in mitigating various environmental impacts .…”

Absorption and Adsorption of Heavy Metals by Microalgae

“…Microalgal biomass has been successfully used as sorbing material (Corder & Reeves, 1994;Donmez et al, 1999;Klimmek et al, 2001;Paperi et al, 2006;Gupta & Rastogi, 2008, 2009Aneja et al, 2010;Colica et al, 2010). The vast majority of the studies were conducted with synthetic solutions containing single metal ion and only limited information is available on biosorption by active (living cells) or inactive (nonliving cells) prokaryotic or eukaryotic biomass exposed to a mixture of several metals simultaneously (Mendoza-Cozatl et al, 2006;Topperwien et al, 2007;Monteiro et al, 2011). In a few studies, the effect of dissolved organic matter on metal speciation and detoxification is also addressed (Lamelas & Slaveykova, 2007;Lamelas et al, 2009).…”

Microalgae Improve the Photosynthetic Performance of Rice Seedlings (Oryza sativa L.) under Physiological Conditions and Cadmium Stress

“…The rich spectrum of mechanisms that allow microalgae to survive and thrive in the presence of heavy metals and at the same time to accumulate these metals in their cells, makes them suitable for practical application as a means of bioremediation (phycoremediation) [18,22,25]. It has been proposed that microalgae remove heavy metals directly from contaminated water in two main ways: the first is the metabolism-dependent uptake of metals by cells at low concentrations of contaminants, and the second is by biosorption, which is an inactive adsorption process [20,26,27]. Furthermore, the mechanisms by which microalgae remove heavy metals from the aquatic environment are: extracellular accumulation, which is more active in living microorganisms; cell surface sorption or complexation (active accumulation of heavy metals by covalent bonding from living and dead microorganisms); and intracellular accumulation, which can only take place by living microorganisms [18][19][20]23,28,29].…”