- The humic acid analogue antraquinone-2,6-disulfonate (AQDS) serves as an electron shuttle in the electricity-driven microbial dechlorination of trichloroethene to cis-dichloroethene. Aulenta, F., Maio, V.D., Ferri, T., Majone, M. Bioresour. Technol. (2010)