Photocatalysis and biodegradation of pharmaceuticals in wastewater: effect of abiotic and biotic factors

Pharmaceuticals (PhACs) are a class of emerging contaminants of global concern due to their ubiquitous nature, persistence and capability of affecting humans and aquatic lives negatively even at very low concentrations. Conventional wastewater treatment procedures are generally inadequate for removing these contaminants. Photocatalysis, an advance oxidation process (AOP), has been widely used in eliminating PhACs from wastewater. This is due to its low operational cost compared to other AOPs. However, the problem of complete mineralization of PhACs by photocatalysis remains a challenge. In this review, we discussed photocatalysis, biodegradation and mechanisms of action for the degradation of PhACs in wastewaters. The application of a combined photocatalytic biodegradation systems for the degradation of PhACs in wastewater was also presented. It is worthy of note that several operating parameters such as the biotic and abiotic factors are pivotal to an efficient photocatalytic and biodegradation treatment systems. Therefore, an integrated photocatalysis/biodegradation system is essential to achieving a complete mineralization of PhACs; other advantages of this treatment technique include low energy cost, effective degradation process, generation of non-toxic by-product and self-sustenance energy generation.