Biodegradation of nonylphenol ethoxylates (NPEOs) by Bacillus sp. LY, with heterotrophic nitrification ability was investigated. The results showed that NPEOs were readily degraded by Bacillus sp. LY with more than 80% of the total NPEOs being removed within 7 days. Heterotrophic nitrogen removal occurred simultaneously during the biodegradation period of NPEOs. NPEOs were biodegraded through a nonoxidative pathway, through which NPEOs were degraded via sequential removal of ethoxyl units to the nonylphenol. To the authors' knowledge, it is the first report on the biodegradation of NPEO contaminants by a microorganism capable of heterotrophic nitrogen removal.