Electro-dewatering (EDW) is an innovative method for volume reduction of sewage sludge before re utilization and disposal. In this study, dewaterability limit and energy consumption in sludge electrodewatering process were directly explored using in-situ linear sweep voltammetry (LSV) analysis by a high-voltage electrochemical workstation instead of a traditional DC power source. Dewaterability limits of biosolids EDW were identified under a constant-voltage dewatering mode with different applied voltages at 10, 20, 30, 40, and 50 V, independently. The LSV tests reveal that the dewaterability limit of sludge is attributed to the higher electrical resistance of the sludge layer near the anode. The mass of the filtrate flow was linearly proportional to the total amount of electric charge corresponding to the energy consumption in EDW, which elucidated the principal mechanism of EDW. Under a constant-voltage dewatering mode, the applied voltage is a key factor in controlling the energy consumption. Reducing the applied voltage while extending the dewatering time is proposed to reduce the energy consumption and obtain a good dewatering result. As the applied voltage decreased from 50 to 10 V, the energy consumption could be reduced from 403.6 to 80.3 kWh/m(3) removed water, the dewatering times was increased from 6.4 to 85.4 min, and the dry solids content of dewatered cake increased from 16.1 to 34.4 wt%. Those results indicate that LSV is an effective method to reveal the mechanism of EDW and optimize the operation parameters to reduce energy consumption. (C) 2017 Elsevier B.V. All rights reserved.