Metals bioremediation potential using Pseudokirchneriella subcapitata

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.

The use of algae to remove copper and lead from industrial wastewater

“…One example is Spirogyra sp., which in the conditions of pH 5.0 and the initial concentration of 200 mg/L for Pb is able to sorb 80% Pb ions (Gupta & Rastogi 2008), or Chlorella vulgaris, achieving 94.74% saturation with lead ions (Peng et al 2017). Red algae Gelidiella acerosa are able to remove 96.36% copper at pH 5.31 with the initial concentration of 23.87 mg/L (Dulla et al 2020), whereas Chlorella vulgaris, 88% (Ansilago et al 2021). There are few publications concerning biosorption with the use of Raphidocelis subcapitata, and the ones that exist do not refer to heavy metals (Carvalho et al 2015, Hom-Díaz et al 2022, so their ability to remove metal ions, optimum pH conditions or potential substances that could facilitate the process are not yet well known.…”