Comment on "Thermodynamically enhancing propionic acid degradation by using sulfate as an external electron acceptor in a thermophilic anaerobic membrane reactor" by Qiao, W., Takayanagi, K., Li, Q., Shofie, M., Gao, F., Dong, R., Li, Y-Y. Water Res. (2016). (1st June 2017) - Dolfing, Jan