Integrated Approach for Carbon Sequestration and Wastewater Treatment Using Algal–Bacterial Consortia: Opportunities and Challenges

Abstract

Increasing concentrations of carbon dioxide (CO2), one of the important greenhouse gases, due to combustion of fossil fuels, particularly burning coal, have become the major cause for global warming. As a consequence, many research programs on CO2 management (capture, storage, and sequestration) are being highlighted. Biological sequestration of CO2 by algae is gaining importance, as it makes use of the photosynthetic capability of these aquatic species to efficiently capture CO2 emitted from various industries and converting it into algal biomass as well as a wide range of metabolites such as polysaccharides, amino acids, fatty acids, pigments, and vitamins. In addition, their ability to thrive in rugged conditions such as seawater, contaminated lakes, and even in certain industrial wastewaters containing high organic and inorganic nutrients loads, has attracted the attention of researchers to integrate carbon capture and wastewater treatment. Algae offer a simple solution to tertiary treatments due to their nutrient removal efficiency, particularly inorganic nitrogen and phosphorus uptake. The algal–bacterial energy nexus is an important strategy capable of removing pollutants from wastewater in a synergistic manner. This review article highlights the mechanism involved in biological fixation of CO2 by microalgae, their cultivation systems, factors influencing algal cultivation in wastewater and CO2 uptake, the effect of co-cultivation of algae and bacteria in wastewater treatment systems, and challenges and opportunities.

Chlamydomonas reinhardtii, a Reference Organism to Study Algal–Microbial Interactions: Why Can’t They Be Friends?

“…Therefore, the addition of oxygen-producing microalgae to the process has become a promising way to reduce costs in wastewater treatment. Moreover, microalgae make this process more environmentally friendly, since the bacterial release of the greenhouse gas CO 2 is reduced by algal fixation [ 138 , 139 ], as recently reviewed by [ 140 , 141 ]. Importantly, bacteria naturally present in wastewater effluents promote the growth of microalgal species including Chlamydomonas, which in turn enhances the water treatment process [ 142 ].…”

<em>Chlamydomonas Reinhardtii, </em>a Reference Organism to Study Algal-Microbial Interactions. <em>Why Can’t They Be Friends</em>

“…Therefore, the addition of oxygen-producing microalgae to the process has become a promising way to reduce costs in wastewater treatment. Moreover, microalgae make this process more environmentally friendly, since the bacterial release of the greenhouse gas CO2 is reduced by algal fixation [135,136], recently reviewed by [137,138]. Importantly, bacteria naturally present in wastewater effluents promote the growth of microalgal species including Chlamydomonas, which in turn enhances the water treatment process [139].…”

Optimization of atmospheric carbonation in the integrated treatment immediate one-step lime precipitation and atmospheric carbonation. The case study of slaughterhouse effluents

“…This integrated solution is recognized for its low cost, simplicity, eco-friendly technology and high efficiency in removing contaminants, like organic matter and nitrogen (Madeira et al [3]. However, this treatment process needs to be studied in detail, since the ability of the atmospheric CO 2 to be transferred to the aqueous phase depends on factors, such as concentration of CO 2 in the atmosphere, area at gas-liquid interface, contact time and solution properties (including pH, temperature, concentration of dissolved salts, and others) (Viswanaathan et al [9]. Lately, the capture of atmospheric CO 2 has deserved the attention of several researchers [10].…”