Given the increasing number of cases of water eutrophication and large quantities of naturally grown algae, this study collected algae for bioethanol production from a; eutrophic water body. The compositions of alga biomass collected from the eutrophic; water body are more complicated than pure culture. The saccharification technique is; also different from conventional. This study applied an electrocoagulation/flotation (ECF) system to recycle eutrophic algae. After pretreatment processes, this study investigated three types of algal biomass to determine the optimal conditions for acid saccharification: Al-containing algal biomass (S1), Fe-containing algal biomass (S2), and raw algal biomass (S3). The results revealed that S1 and S3 attained the highest reducing sugar yields after a 30-min reaction under the following conditions: sulfuric acid concentration = 6% (WV), liquid solid ratio (LSR) = 26, and temperature = 120 degrees C. The maximum reducing sugar yield from S2 occurred at an LSR of 22, yielding up to 156 mg glucose/g and achieving a xylose yield that is twice higher than the glucose yield. Therefore, adopting an ECF system with an Fe electrode for recycling algae advances current research on the saccharification of algae. Recently, the proposed technique has been approved as a new patent by Taiwan Government. (C) 2016 Elsevier Ltd. All rights reserved.