Investigation of the properties and mechanism of activated sludge in acid-magnetic powder conditioning and vertical pressurized electro-dewatering (AMPED) process

Although sludge electro-dewatering is a promising sludge dewatering technology, it generally requires pre-treatment of sludge to achieve the desired dewatering effect. Herein, a technique was designed to use acid -magnetic powder conditioning as a pretreatment for sludge electro-dewatering, and the impacts of acid -magnetic powder conditioning and vertical pressurized electro-dewatering process were revealed. Pretreat-ment with CPAM conditioning, which is commonly used in sludge dewatering, and acid-magnetic powder conditioning conditioning were conducted on the sludge. The conditioned sludge was conducted electro-dewatering after precipitated. The results showed that under optimal conditions (pH = 5, 0.15 g magnetic powder/g DS), the dewatered sludge's MC was 48.5 %, a decline of 9.13 % compared to the CPAM conditioning. Acid-magnetic powder conditioning enhances the electro-dewatering effect mainly by destroying the substrate and reducing the sludge resistance. Pearson analysis revealed that conductivity showed an extremely strong positive correlation with SCOD (r = 0.812, p < 0.05) and extracellular polymeric substance (r = 0.811, p < 0.05) and a negative correlation with organic matter in the TB layer (r =-0.862, p < 0.05), and the sludge TB layer was significantly disrupted by acid-magnetic powder conditioning and vertical pressurized electro-dewatering. And there was a significant decrease in sludge impedance after conditioning. These findings demonstrate that acid -magnetic powder conditioning can greatly enhance the dewatering efficiency and is a potential pretreatment technology to assist in the sludge electro-dewatering process.