Thousands of tones of antibiotics are consumed every year in the world for both therapeutic and nontherapeutic purposes. Most of them may poorly be absorbed in the digestive tracts of human and animals. About 25–75% is eventually excreted as unmetabolized parent compounds into domestic sewage, which are harmful to the aquatic environment. For instance, the antibiotics were detected in half of the sites from a network of 139 streams across
30 states in the US [1].