LAUSR

Industrial and human activities generate a huge volume of polluted effluents with toxic compounds posing ecosystem and human health at risk when discharged into the environment untreated or partially treated. Therefore, industrial polluted effluents must be efficiently treated before being discharged into the environment. Also, although traditional wastewater treatment plants (WWTPs) are efficient in abating nitrogen and carbon concentrations, they have shown to be ineffective in the removal of certain types of compounds such as the so‐called emerging pollutants (e.g., pharmaceuticals, pesticides, personal care products). Thus, such compounds pass the WWTP unaltered and, thereby, they enter the environment with the consequent threat to wild and human life. Concern arises because many emerging pollutants are either endocrine disruptor or carcinogen compounds. Therefore, efficient treatment to remove such compounds before being discharged into the environment or water bodies is required. Different physical, chemical and physicochemical techniques have been widely used for the removal of pollutants from wastewater. However, such techniques are often costly, not practical and generate secondary pollution. In this context, microbial remediation is seen as an effective, sustainable and environmentally friendly promising technology to remove hazardous pollutants from wastewater. Thus, compared to physical, chemical and physicochemical remediation, bioremediation presents the following advantages: ecological, no secondary pollution, cost‐effective, little disturbance and low energy input. In addition, bioremediation will contribute to achieving some of the sustainable development goals for 2030 set by the United Nations in 2015 (United Nations 2015, https://www. un.org/sustainabledevelopment/summit/). Bioremediation processes use fungi, bacteria, algae or plants to remove wastewater pollutants or transform them into less toxic forms and can be performed in situ and ex situ. The former is considered slow and difficult to control and optimise, whereas the latter uses specially designed bioreactors to reach optimal bioremediation. To solve the limitations found in traditional bioremediation processes, researchers are keen to develop new bioremediation strategies. Modified microbial strains with enhanced bioremediation properties could be engineered but studies ensuring the innocuity of entering such strains in the natural environment should be performed beforehand to prevent horizontal gene transfer. Microbial fuel cells have appeared as an interesting alternative for wastewater bioremediation with the additional advantage of producing electricity concurrently (Mukherjee et al., 2022, https://doi.org/10.1016/j.matpr.2021.12. 326), but some constraints such as high cost and low electricity generation have to be sorted out. Also, microalgal bioremediation has emerged as a promising technology to remove nutrients and pollutants from wastewater (Sharma et al., Bioresour Technol. 2022;44:126129). Furthermore, microalgal bioremediation presents the asset of being able to recover resources from wastewater through biorefinery, thus, contributing to a circular economy. However, high nutrient demand for microalgal growth, harvesting problems and undeveloped downstream processes are currently limiting the commercial application of this technology. In addition, the use of bionanomaterials for the removal of pollutants from wastewater has been reported to be more advantageous than chemically synthesised nanomaterials but studies related to their toxicity towards wildlife, their regeneration and regulation of their degradation are required (Malik et al., this issue). For real applications, scaling up bioremediation processes is essential. However, most research dealing with bioremediation of wastewater has been performed in batch and on laboratory scale. Research on large‐scale and continuous bioremediation processes need to be studied for large commercial applications. In addition, there are few studies on real wastewater bioremediation. Hence, it is important to investigate bioremediation in real wastewater to assess its practical feasibility. To address the above‐mentioned limitations, multidisciplinary research including chemical engineers, biotechnologists, biochemists and material scientists is imperative. In addition, because single treatments are usually limited, the use of joint bioremediation technologies should be explored.