Pharmaceutical wastes in wastewater are a cause for alarm worldwide as it contributes to pharmaceutical resistance, not to mention that most clinical drugs are resistant to conventional treatment methods. Fenton and Fenton-like treatment of water are among the emerging advanced oxidation processes (AOPs) that could potentially degrade these recalcitrant pollutants in water. It uses a catalyst and an oxidant to generate powerful radicals that can react with the pollutants to cause their complete mineralization. Here, Engr. Lopez and his team developed a catalyst from waste mussel shell biochar and showed excellent performance for the degradation of diclofenac in water.