Removal of pharmaceutical compounds in water and wastewater using fungal oxidoreductase enzymes

Abstract

Due to recalcitrance of some pharmaceutically active compounds (PhACs), conventional wastewater treatment is not able to remove them effectively. Therefore, their occurrence in surface water and potential environmental impact has raised serious global concern. Biological transformation of these contaminants using white-rot fungi (WRF) and their oxidoreductase enzymes has been proposed as a low cost and environmentally friendly solution for water treatment. The removal performance of PhACs by a fungal culture is dependent on several factors, such as fungal species, the secreted enzymes, molecular structure of target compounds, culture medium composition, etc. In recent 20 years, numerous researchers tried to elucidate the removal mechanisms and the effects of important operational parameters such as temperature and pH on the enzymatic treatment of PhACs. This review summarizes and analyzes the studies performed on PhACs removal from spiked pure water and real wastewaters using oxidoreductase enzymes and the data related to degradation efficiencies of the most studied compounds. The review also offers an insight into enzymes immobilization, fungal reactors, mediators, degradation mechanisms and transformation products (TPs) of PhACs. In brief, higher hydrophobicity and having electron-donating groups, such as amine and hydroxyl in molecular structure leads to more effective degradation of PhACs by fungal cultures. For recalcitrant compounds, using redox mediators, such as syringaldehyde increases the degradation efficiency, however they may cause toxicity in the effluent and deactivate the enzyme. Immobilization of enzymes on supports can enhance the performance of enzyme in terms of reusability and stability. However, the immobilization strategy should be carefully selected to reduce the cost and enable regeneration. Still, further studies are needed to elucidate the mechanisms involved in enzymatic degradation and the toxicity levels of TPs and also to optimize the whole treatment strategy to have economical and technical competitiveness.

Degradation of tetracyclines and sulfonamides by stevensite‐ and biochar‐immobilized laccase systems and impact on residual antibiotic activity

“…With a sole exception, there is general agreement about the enhancement of laccase‐triggered antibiotics degradation ensured by the addition of redox mediators . However, in the present study, of the four tested mediators, only ABTS and syringaldehyde met this expectation.…”

“…A variety of techniques have been proposed to prevent antibiotics spread, such as advanced oxidation and membrane processes, adsorption and combined methods . The research on enzyme‐catalyzed transformation methods for antibiotics and organic micropollutants have been explored in recent years . In this respect, laccase (E.C.…”

“…1.10.3.2.; para ‐benzenediol:oxygen oxidoreductase), a copper‐containing oxidase, appears to be very promising due to its low substrate specificity and its ability to bring about the mono‐electronic oxidation of a wide array of aromatic compounds using molecular oxygen as the final electron acceptor. Consequently, due to its low substrate specificity, laccase has been successfully used for the oxidation of a wide variety of organic pollutants, such as pesticides, polycyclic aromatic hydrocarbons, dyes and pharmaceutical compounds, including antibiotics …”

“…So far, however, there are only two studies where functionalized biochar was used to immobilize laccase . Another point that deserves attention regards the source of laccase; in fact, with few exceptions, the large majority of studies dealing with laccase‐catalyzed oxidation have relied on Trametes versicolor laccase (TvL) …”

Eco-Friendly Remediation to Mitigate the Toxic Effects of Emerging Contaminant Diclofenac

“…But chemical and physical approaches of remediation are not enough to reduce the effect of pollution as they are costly and generate recalcitrant compounds. In order to employ a fast, simple, cost-effective and eco-friendly approach bioremediation is being explored for effective DCF removal [33]. Bioremediation can play a crucial role in cleaning the sites of contamination.…”