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Electrocoagulation; Aluminum electrodes; Decentralized water treatment; Drinking water treatment; Coagulant generation; Current density; Chloride concentration; Electrode passivation; Pitting corrosion; Electrode performance.
College
College of Engineering
Mentor Information
Katherine Alfredo
Description
Electrocoagulation (EC) is a promising alternative to conventional chemical coagulation for decentralized drinking water treatment because it generates coagulants on-site , reducing the need for chemical transportation and storage in remote communities. In EC systems, an electric current applied to aluminum electrodes releases species that form solid coagulants capable of removing groundwater contaminants. However, long-term operation remains poorly understood, as electrode degradation through passivation (deposit accumulation) and pitting may reduce coagulant production and treatment efficiency, highlighting the need for practical indicators to track performance. The objective of this study is to evaluate the relationship between current, electrode condition, and aluminum production in a lab-scale EC system under varying chloride concentrations (21-166 mg/L CaCl₂). The EC reactor was operated at a constant voltage of 12 V for 60 hours. Water samples were collected every 20 hours for total aluminum and pH analysis, while current was continuously monitored. At 60 hours, mass loss and microscopic observations were performed to assess pitting and passive film formation. A positive correlation was observed between current and aluminum, although high solution pH suggested the presence of dissolved aluminum species that reduced the reliability of current as a performance indicator. Higher chloride concentrations sustained aluminum production by limiting passivation, whereas lower chloride concentrations accelerated passivation, reducing current and aluminum release over time. . Visible pitting and passivation patterns, together with current measurements, may provide practical indicators of declining EC performance, but their reliability is influenced by non-coagulating aluminum species present at high pH.
Evaluation of Aluminum Electrocoagulation Performance Indicators for Decentralized Drinking Water Treatment
Electrocoagulation (EC) is a promising alternative to conventional chemical coagulation for decentralized drinking water treatment because it generates coagulants on-site , reducing the need for chemical transportation and storage in remote communities. In EC systems, an electric current applied to aluminum electrodes releases species that form solid coagulants capable of removing groundwater contaminants. However, long-term operation remains poorly understood, as electrode degradation through passivation (deposit accumulation) and pitting may reduce coagulant production and treatment efficiency, highlighting the need for practical indicators to track performance. The objective of this study is to evaluate the relationship between current, electrode condition, and aluminum production in a lab-scale EC system under varying chloride concentrations (21-166 mg/L CaCl₂). The EC reactor was operated at a constant voltage of 12 V for 60 hours. Water samples were collected every 20 hours for total aluminum and pH analysis, while current was continuously monitored. At 60 hours, mass loss and microscopic observations were performed to assess pitting and passive film formation. A positive correlation was observed between current and aluminum, although high solution pH suggested the presence of dissolved aluminum species that reduced the reliability of current as a performance indicator. Higher chloride concentrations sustained aluminum production by limiting passivation, whereas lower chloride concentrations accelerated passivation, reducing current and aluminum release over time. . Visible pitting and passivation patterns, together with current measurements, may provide practical indicators of declining EC performance, but their reliability is influenced by non-coagulating aluminum species present at high pH.
