Mineralization of Antibiotics in Wastewater Via Photocatalysis

Antibiotics are among the prominent class of pharmaceuticals considered emerging pollutants. This class of compounds has found its way into diverse arrays of water bodies in the environment due to their incomplete decomposition, and also the indiscriminate disposal of pharmaceutical waste from industries, farms, and medical centers. This is often through soluble reactive effluent, water run-offs due to rainfall on agricultural facilities and untreated sewages. Their concentration in the environment usually exceeds the permitted levels, which in turn leads to the possibilities of bio-magnifications and bioaccumulation in the food chain. Consequently, they constitute safety hazards and it is important to remove this class of compounds. Another concern is the development of resistance by the micro-organisms, which could render these drugs ineffective and useless if serious control is not put in place to regulate their usage and presence in the environment. Although different conventional methods are currently used in water treatment plants, the presence of pharmaceuticals, such as antibiotics, has been confirmed in different recycled water meant for consumption. Recently, advanced oxidation processes (AOPs) have emerged as a useful technique for the mineralization of these antibiotics in water via the use of heterogeneous photocatalysis. In this review, a background study on the origin and fate of pharmaceuticals such as antibiotics, and the usefulness of photocatalysis (a prominent method of advanced oxidation process (AOPs)) in the mineralization of this class of pharmaceuticals into less harmful compounds is assessed. The degradation pathway of different classes of antibiotics is also discussed using specific examples of compounds in each of the classes.