Enzyme-coated biochar as a sustainable solution for water and wastewater treatment

Traditional wastewater treatment plants are not suitable for removing potentially hazardous compounds released daily into effluents, resulting in their accumulation in the environment. Therefore, developing efficient and sustainable water treatment technologies is a public health issue crucial to ensuring the development of our civilization. Enzymatic wastewater treatment is a promising approach for the remediation of different contaminants by breaking down and transforming the harmful ones into less toxic, biodegradable, and easily collected parts. It is considered safe, green, and efficient. The resulting system avoids enzyme leaching and high operating cost when applied in its immobilized form. Within this context, biochar is emerging as a sustainable solid support for enzyme immobilization since it presents a large surface area, an easily modifiable surface, and eco-friendly and inexpensive synthesis. The union of the adsorbent properties of biochar with enzymatic catalysis allows obtaining materials with dual functionality, which is more efficient in removing contaminants than isolated techniques. This review covers articles from the last decade that describe the use of enzymes immobilized on biochar for water and wastewater treatment, emphasizing the enzymes that can be used for the biodegradation of contaminants, the process of biochar synthesis, a comparison of the use of biochar with other materials available as a support, enzymatic immobilization and the experimental parameters that affect the immobilization efficiency, the biochar characteristics that influence its use as a support and the applicability of the systems described in the literature for removal of contaminants. Enzyme-coated biochar combines adsorption and biodegradation, offering an efficient approach to remove emerging aqueous contaminants.