Metals bioremediation potential using Pseudokirchneriella subcapitata

Mônica Ansilago,Franciéli Ottonelli,Emerson Machado De Carvalho

doi:10.5327/z21769478834

Abstract

Microalgae are unicellular organisms, photosynthesizers that present cell duplication exponentially and biosorption capacity of nutrients dissolved in water. The objective of this work was to evaluate the capacity of the microalga Pseudokirchneriella subcapitata for bioremediation of metals and salts. In this aspect, the reduction of the metals and salts in the synthetic effluents by the microalga P. subcapitata was evaluated: (T1) culture medium (control); (T2) culture medium contaminated with aluminum chloride; (T3) culture medium contaminated with ferrous sulfate; (T4) culture medium contaminated with zinc sulfate; (T5) culture medium contaminated with the combination of aluminum chloride, ferrous sulfate and zinc sulfate. The bioremediation process was evaluated by comparing culture media with suspended microalgae to a filtrate version of the same medium. Iron and zinc metals, as well as nitrogen and phosphorus salts, showed depleted values in the filtered medium, indicating efficiency in the treatment of water by microalgae. Aluminum content was below the limit of detection in all treatments. The cumulative values in the microalgae biomass were, in descending order: nitrogen, zinc, iron and phosphorus, thus indicating the assimilation of the contaminants in the algal biomass. In addition, high biomass production of the microalgae was observed. The highest production rate was verified in the synthetic effluent with the association of metals, indicating a synergy between contaminants, which was probably responsible for reducing the toxic effect on the microalgae. These results indicated high potential for bioremediation by microalga P. subcapitata, besides the possibility of using algal biomass for biotechnological applications.

Highlights

Population growth and the development of new production technologies generate continuous environmental impacts
It is possible to observe an antagonistic dynamic, in which the effect of zinc on the exposure of other chemicals, such as iron and aluminum, resulted in the reduction of its toxic effect to microalgae, bringing about effects different from those expected for the action of contaminants alone, which result from synergistic, potentiation, antagonistic and additive interactions (Mozeto and Zagato, 2008)
This corroborates the results obtained in the present study, since the treatment contaminated with all metals (T5) obtained a higher rate of algal biomass duplication, which can indicate synergy between the contaminants, reducing the toxic effects

Summary

Introduction

Population growth and the development of new production technologies generate continuous environmental impacts. These bioactive compounds are essential inputs for the food, pharmaceutical and cosmetic industries They are an energy source (Priyadarshani and Rath, 2012) and present high market value due to the low costs of the production process. The species Pseudokirchneriella subcapitata has been reported in nutrient removal studies concerning elements such as nitrogen and phosphorus (Gonçalves et al, 2016), as well as in toxicity studies on media containing toxic metals (Gao et al, 2016; Sousa et al, 2018) It is a half moon-shaped, single-celled green algae, with a single chloroplast containing chlorophyll a and b (Granados et al, 2008). The microalga P. subcapitata presents desirable characteristics for wastewater bioremediation, experiments in controlled environments are still needed to evaluate its ability to remove nutrients of water, whether salts and/or metals, as well as to evaluate the production of algal biomass in liquid media substrates with the presence of contaminants. The objective of this study was to evaluate the bioremediation capacity of metals and salts by P. subcapitata microalgae in laboratory culture

Materials and Methods

Objective

Findings

Conclusion