Abstract
The valorization of Spirulina as a potential biosorption material to treat contaminated wastewater was evaluated. Batch experiments were conducted to study the influence of pH value and ionic strength on the biosorption capacity of Spirulina. Higher removal capacity was observed at pH 5.2, while higher ionic strength was found to result in lower adsorption capacity, which suggests that ion exchange is a relevant mechanism for Pb (II) adsorption on Spirulina. The immobilization of Spirulina on alginate beads was found not only to increase the adsorption capacity, but also to overcome limitations such as unacceptable pressure drops on column systems. The Langmuir model was the most appropriate model to describe the biosorption equilibrium of lead by free and immobilized Spirulina. The experimental breakthrough curves were evaluated using the Thomas, Bohart-Adams, and dose-response models. The experimental results were most properly described by the dose-response model, which is consistent with previous results. The adsorption capacity of Spirulina was found to increase linearly with the influent lead concentration (in the range 4–20 mg L−1) at 1.6 mL min−1 flow rate. Batch and column experiments were compared to better understand the biosorption process. The promising results obtained indicate the potential use of Spirulina immobilized on alginate beads to treat industrial wastewater polluted with toxic metals.
Highlights
The increasing pollution of the environment by heavy metals due to industrial activity poses serious risks for human health and living organisms
The presence of lead in various types of wastewater should be controlled according to the standard for the permitted amount of metal determined by the Environmental Protection Agency [2]
A biosorbent for the removal of lead from aqueous solutions was prepared from the microalga Arthrospira (Spirulina) platensis, which was obtained from the Spanish Bank of Algae (BEA 0007B), University of Las Palmas de Gran Canaria
Summary
The increasing pollution of the environment by heavy metals due to industrial activity poses serious risks for human health and living organisms. Biosorption has been proposed as an emerging and low-cost alternative based on the sorption of dissolved pollutants on a biomaterial This technology overcomes the most relevant drawbacks of conventional methods, mainly the indirect disposal of toxic metal sludge and the limited adsorption efficiency at low metal concentrations [3]. Biomaterials, such as bacteria, algae, fungi, and agricultural wastes, have been proposed as low-cost biosorbents for the removal of heavy metals from wastewater [4]. The breakthrough curve was used to study the efficiency of the continuous process with the proposed biosorbent
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