Ahmad AbuSeif, Yousef AbuSeif, Siyu Gan, Zia ur Rehman, Chunli Zheng
Sludge dewatering is a critical step in wastewater treatment, but conventional methods often rely on high chemical dosages and energy-intensive mechanical processes while achieving only limited moisture reduction. Recent advances such as bio-flocculants and electro-osmotic dewatering have improved dewatering performance, yet these techniques are constrained by high costs, inconsistent efficacy, or excessive energy use. Moreover, their impact on downstream thermal drying equipment performance remains underexplored, representing a significant research gap. To address this gap, this study develops a simulation-driven framework that links upstream moisture content reduction to heat pump drying efficiency. Using a low-concentration cationic polyacrylamide (CPAM) flocculant (0.01% dose) for sludge pretreatment, we reduced sludge moisture content from 82.7 to 22.7% and evaluated the effects on a subsequent heat pump dryer. The results show that this optimized pretreatment increased the heat pump’s coefficient of performance (COP) by 37.8% and extended its maintenance interval by 42.3% relative to untreated sludge. This low-dose chemical approach achieved greater efficiency gains than traditional high-dose flocculation methods, with a conventional aluminum sulfate treatment (15 mg/L) yielding a 33.2% COP improvement. The integrated model also predicts substantial operational cost savings of around $27,450 per year per heat pump unit under the optimized CPAM treatment. These findings demonstrate the significant energy and economic benefits of linking advanced dewatering pretreatment to downstream thermal processing performance. By quantifying these cascading benefits, the study introduces a novel and more sustainable strategy for sludge management, bridging the gap between sludge dewatering innovations and improved thermal equipment efficiency.