Coconut shell activated carbon (CSAC) reinforced municipal sludge by high pressurized electro-dewatering with constant voltage gradient

Electro-dewatering (EDW) technology is a promising and effective municipal sludge dewatering technology. This study explores the effects of different voltage modes and coconut shell activated carbon (CSAC) on the performance of EDW and the resulting sludge cake. The results indicated that under a constant voltage gradient of 36 V/cm, the moisture content (<i>M_c</i>) of sludge significantly decreased from 88% to 64%, and there was a noticeable improvement in the resistance and temperature of sludge cake compared to the constant voltage mode. After adding CSAC, <i>M_c</i> of sludge was further reduced to 49%, the conductivity of the sludge was significantly increased, and the maximum current reached 0.34 A. The combined use of both methods also reduced the energy consumption during the sludge dewatering process, achieving a reduction of 78.14 Wh/kg._H2O compared with constant pressure electro-dewatering. Furthermore, this paper utilizes scanning electron microscopy (SEM) to observe the internal pore distribution in sludge, thereby elucidating the underlying mechanisms.