Biochar production from microalgae: a new sustainable approach to wastewater treatment based on a circular economy

• Published in: Enzyme and microbial technology Vol. 169; p. 110281
• Main Authors: Costa, Jorge Alberto Vieira, Zaparoli, Munise, Cassuriaga, Ana Paula Aguiar, Cardias, Bruna Barcelos, Vaz, Bruna da Silva, Morais, Michele Greque de, Moreira, Juliana Botelho
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-09-2023
• Subjects: Circular economy; Hydrothermal carbonization; Microalgae biomass; Pyrolysis; Torrefaction; Microalgae biomass; Pyrolysis; Torrefaction; Circular economy; Hydrothermal carbonization
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/j.enzmictec.2023.110281

The generation of wastewater due to human activities are the main responsible for environmental problems. These problems are caused by the large amount of organic and inorganic pollutants related to the presence of pesticides, metals, pathogens, drugs and dyes. The photosynthetic treatment of effluents emerges as a sustainable and low-cost alternative for developing wastewater treatment systems based on a circular economy. Chemical compounds present in wastewater can be recovered and reused as a source of nutrients in microalgae cultivation to produce value-added bioproducts. The microalgal biomass produced in the cultivation with effluents has the potential to produce biochar. Biochar is carbon-rich charcoal that can be obtained by converting microalgae biomass through thermal decomposition of organic raw material under limited oxygen supply conditions. Pyrolysis, torrefaction, and hydrothermal carbonization are processes used for biochar synthesis. The application of microalgal biochar as an adsorbent material to remove several compounds present in effluents is an effective and fast treatment. This effectiveness is usually related to the unique physicochemical characteristics of the biochar, such as the presence of functional groups, ion exchange capacity, thermal stability, and high surface area, volume, and pore area. In addition, biochar can be reused in the adsorption process or applied in agriculture for soil correction. In this context, this review article describes the production, characterization, and use of microalgae biochar through a sustainable approach to wastewater treatment, emphasizing its potential in the circular economy. In addition, the article approaches the potential of microalgal biochar as an adsorbent material and its reuse after the adsorption of contaminants, as well as highlights the challenges and future perspectives on this topic.
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•Microalgal biomass produced from wastewater treatment can be used to obtain biochar.•Microalgae biochar is an adsorbent promise to remove contaminants in effluents.•The application of microalgal biochar is related to its properties.•The circular bioeconomy context can be applied to the production of biochar.•Microalgae biochar can integrate energy production and resource recovery.