Heavy Metal Removal (Copper and Zinc) in Secondary Effluent from Wastewater Treatment Plants by Microalgae

Abstract

Microalgae is used for the removal of heavy metals from a wastewater treatment plant discharge. Laboratory-scale experiments are described that characterize the heavy metal uptake of copper and zinc by three microalgae strains: Chlorella vulgaris, Spirulina maxima, and a naturally growing algae sample found in the wastewater from a wastewater treatment plant (containing Synechocystis sp. (dominant) and Chlorella sp. (common) and a few cells of Scenedesmus sp.) Tests were conducted using untreated and autoclaved secondary effluent as a substrate. In the untreated secondary effluent trial, the microalgae removed up to 81.7% of the copper, reaching a lowest final concentration of 7.8 ppb after 10 days. Zinc was reduced by up to 94.1%, reaching 0.6 ppb after 10 days. The removal rates varied significantly with the microalgae strain. Higher heavy metal removal efficiencies were obtained in the autoclaved secondary effluent than the untreated secondary effluent, suggesting microorganisms already present in secondary effluent contribute negatively and compete with microalgae for nutrients, hindering microalgae growth and uptake of heavy metals. Inoculated samples showed decreased heavy metal concentrations within 6 h of initial inoculation, suggesting microalgae do not require long periods of time to achieve biosorption of heavy metals.

Green Approach in the Bio-removal of Heavy Metals from wastewaters

“…only up to 2%. Meanwhile, Chan et al [13] reported that Chlorella vulgaris and Spirulina maxima capable of reducing Zn concentration in DW up to 96.3% and 94.9%, respectively. Other than that, Hamouda et al [25] studied removal of heavy metals in industrial wastewater using green microalgae and found that Scenedesmus obliquus able to reduce Cd about 70% in the light and dark culture condition.…”

A multilevel sustainability analysis of zinc recovery from wastes

“…Table 3 shows some examples of zinc removal using various types of conventional treatment methods (Kul and Oskay, 2015; Charerntanyarak, 1999;Rubio and Tessele, 1997;Juang and Shiau, 2000;Ujang and Anderson, 1996;Álvarez-Ayuso et al, 2003;Dermentzis et al, 2011). However, conventional approaches are normally inefficient in removing heavy metals present at low concentration (10-100 mg/L) and the operations are costly and energy intensive (Suresh Kumar et al, 2015;Chan et al, 2014;Mehta and Gaur, 2005). Microbial electrosynthesis process serves the purpose of recovery of heavy metals including iron, copper and zinc, present at low concentration in wastewaters (Sadhukhan et al, 2016a).…”

“…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 .…”

“…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.…”

Eco-friendly and cost-effective superabsorbent sodium polyacrylate composites for environmental remediation

“…Heavy metals are recognized as one of the most harmful pollutants in the environment, due to their detrimental effects on aquatic environments and human beings, such as high toxicity, bioaccumulation, and non-degradability [1][2][3]. Common sources of heavy metal pollution are mainly mining and industrial activities such as petroleum refining, paints and pigments, pesticide production, chemical manufacturing, mining and smelting activities, and electroplating [1,4].…”