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An integrated pump-suction electrocoagulation system for accelerated hardness removal: Process intensification and
Yunxian Liu1, Yuexin Chang1, Xu Liu1
1Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
Water Research
|June 25, 2026
Summary
This study introduces an integrated pump-suction electrocoagulation (IPE) system for efficient hard-water softening. The IPE system significantly enhances hardness and turbidity removal rates while reducing energy consumption compared to conventional methods.
Area of Science:
- Environmental Science
- Electrochemistry
- Materials Science
Background:
- Conventional electrochemical softening faces limitations due to spatial separation of precipitation and solid-liquid separation, leading to slow kinetics and high chemical demand.
- Existing membrane-free systems struggle with process integration and efficiency.
Purpose of the Study:
- To develop and evaluate intensified electrochemical systems for efficient hard-water softening.
- To investigate the performance of an integrated pump-suction electrocoagulation (IPE) system that spatially integrates key processes within a single reactor.
Main Methods:
- Development of three progressively intensified systems: pump-suction chemical flocculation (PCF), split-type electrocoagulation (SPE), and integrated pump-suction electrocoagulation (IPE).
- Utilizing multiphysics simulations to analyze flow fields and electric potential gradients within the IPE system.
- Conducting experiments to measure hardness and turbidity removal efficiencies and specific energy consumption.
Main Results:
- The IPE system demonstrated significantly enhanced reaction coupling, increasing Mg hardness and turbidity removal rate constants by approximately 5-fold and 12-fold, respectively, compared to single pump-suction systems.
- Rapid reduction in turbidity from 250 NTU to 22 NTU within 2.5 minutes, with Ca and Mg hardness removal efficiencies reaching 92.68% and 96.36%.
- IPE system achieved a specific energy consumption of 12.60 kWh/kg CaCO3, a 32.44% reduction compared to the SPE system.
Conclusions:
- The IPE system effectively integrates cathodic alkalinity generation and anodic Al species release, creating a confined alkaline microenvironment for intensified water softening.
- The synergistic interaction between cathode-induced precipitation and anodically released Al species accelerates nucleation, crystal growth, and the formation of aggregates with improved settling properties.
- Reconstructing electrochemical reaction space offers a compact, low-chemical, and energy-efficient strategy for hard-water softening by shifting rate-limiting steps to mass transfer and particle aggregation.
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