Remediation of Aquaculture Wastewater Using the Microalga Chlorella sorokiniana

Libardo A Lugo,Olafur P Palsson,Sigfus Bjornsson,Sigurdur Brynjolfsson,Hakon Skulason,Ragnheidur I Thorarinsdottir,Skuli Johannsson

doi:10.3390/w12113144

Abstract

The aquaculture industry requires solutions to several environmental challenges in order to become sustainable, including adequate wastewater management. Aquaculture wastewater (AWW) is rich in nitrogen, phosphorus, organic carbon, and other elements essential for microalgae. Due to the potential for AWW to be used as a microalgal growth medium and the potential of Chlorella sorokiniana to remediate wastewater, the growth of this species in AWW was evaluated. The microalgal growth in AWW was compared to the growth in a modified BG11 growth medium containing similar nutrient concentrations as the AWW. The effect of pH regulation and air-lifting the cell suspension at different airflow rates was also studied. As a result, it was found that C. sorokiniana can grow successfully in AWW; however, its cultivation required pH regulation. This microalga species can reach a biomass concentration of up to 476 mg/L and a biomass productivity of 140 mg/L/day. Furthermore, up to 78% of the nitrogen, 77% of the phosphorus, 70% of the magnesium, 90% of the zinc, and 99% of the nickel contained in the AWW were assimilated by the microalgae. The results of this study show that microalga cultivation in wastewater has great potential to reduce contamination while generating economic benefits.

Highlights

Phycoremediation refers to the use of microalgae or macroalgae to remove or transform pollutants from water and air, nutrients and harmful chemicals from wastewater, and CO2 from waste air [1]
To evaluate the potential of Aquaculture wastewater (AWW) to be used as a microalgal growth medium, the concentration of several chemicals, as well as some physicochemical properties of the AWW, was measured (Table 3)
This study demonstrates the potential and feasibility of the use of the microalga C. sorokiniana to remediate AWW in a large-scale photobioreactor

Summary

Introduction

Phycoremediation refers to the use of microalgae or macroalgae to remove or transform pollutants from water and air, nutrients and harmful chemicals from wastewater, and CO2 from waste air [1]. The pshycoremediation processes involve the production of microalgal biomass. This biomass is a valuable stock in different industries, as several chemicals can be extracted or produced from it. These include biofuels such as biodiesel and bioethanol, which are produced from lipids and carbohydrates, respectively [2], and bioactive medicinal products, such as pigments and polyunsaturated fatty acids (PUFAs), which are commonly used in the health industry and play a vital role as precursors of vitamins, antioxidants, anti-inflammatory compounds, and wound healing additives [3,4]. The raw biomass is regularly used for human and animal consumption. It is highly digestible, contains large quantities of amino acids and proteins, and promotes animal growth and health [5]

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Conclusion