<p>This study investigates the performance of a sequencing batch electro-membrane bioreactor (SB-EMBR) operated under low electric charge loading (39.9 mAh L⁻<sup>1</sup>), focusing on the effects of aeration intensity on treatment performance, biomass activity, and membrane fouling. The reactor was operated at a current density of 10 A m<sup>−2</sup> and three specific aeration demand levels (SADₘ = 0.48, 0.24, and 0.12 m<sup>3</sup>&#xa0;m⁻<sup>2</sup>&#xa0;h⁻<sup>1</sup>). Organic matter and phosphorus removals remained consistently high (&gt; 90% COD removal; TP &lt; 1.0&#xa0;mg L⁻<sup>1</sup>) regardless of aeration intensity. In contrast, ammonium removal efficiency declined from 99.5 to 74.7% as the SADₘ decreased from 0.48 to 0.12 m<sup>3</sup>&#xa0;m⁻<sup>2</sup>&#xa0;h⁻<sup>1</sup>. Batch assays revealed reduced activity of polyphosphate-accumulating organisms under oxygen-limited conditions. The pronounced decrease in the P-release/COD-uptake ratio from 0.172 to 0.0164&#xa0;mol P mol⁻<sup>1</sup> C indicates that TP removal at low dissolved oxygen became predominantly governed by chemical coagulation rather than the biological phosphorus removal process. The calculated Al/P molar ratio of 2.32&#xa0;mol Al mol⁻<sup>1</sup> P was sufficient to sustain phosphorus removal through both precipitation and adsorption onto aluminum hydroxides. Reduced aeration favored anoxic phosphorus uptake, increasing the denitrifying phosphate assimilation potential from 18 to 41%. The membrane fouling rate increased from 1.02 to 4.81&#xa0;kPa d⁻<sup>1</sup> as aeration decreased, mainly due to diminished shear forces, soluble microbial products accumulation (+ 205%), floc size reduction (− 50.1%), and higher capillary suction time (+ 123%). Owing to the short current application (1.6&#xa0;h d⁻<sup>1</sup>), the additional electrocoagulation cost was only 0.07 USD m⁻<sup>3</sup>, lower than values reported for continuous-flow EMBRs. Overall, operation of the SB-EMBR under reduced electric charge loading demonstrated promising energy efficiency while maintaining stable and satisfactory pollutant removal even at low aeration intensities.</p>

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Low electric charge loading in a sequencing batch electro-membrane bioreactor: influence of aeration intensity on treatment performance, biomass activity, and membrane fouling

  • Tiago José Belli,
  • Emerson Souza,
  • Caroline Rodrigues,
  • André Aguiar Battistelli,
  • Wanderli Leite,
  • Miriam Cristina Santos Amaral,
  • Flávio Rubens Lapolli

摘要

This study investigates the performance of a sequencing batch electro-membrane bioreactor (SB-EMBR) operated under low electric charge loading (39.9 mAh L⁻1), focusing on the effects of aeration intensity on treatment performance, biomass activity, and membrane fouling. The reactor was operated at a current density of 10 A m−2 and three specific aeration demand levels (SADₘ = 0.48, 0.24, and 0.12 m3 m⁻2 h⁻1). Organic matter and phosphorus removals remained consistently high (> 90% COD removal; TP < 1.0 mg L⁻1) regardless of aeration intensity. In contrast, ammonium removal efficiency declined from 99.5 to 74.7% as the SADₘ decreased from 0.48 to 0.12 m3 m⁻2 h⁻1. Batch assays revealed reduced activity of polyphosphate-accumulating organisms under oxygen-limited conditions. The pronounced decrease in the P-release/COD-uptake ratio from 0.172 to 0.0164 mol P mol⁻1 C indicates that TP removal at low dissolved oxygen became predominantly governed by chemical coagulation rather than the biological phosphorus removal process. The calculated Al/P molar ratio of 2.32 mol Al mol⁻1 P was sufficient to sustain phosphorus removal through both precipitation and adsorption onto aluminum hydroxides. Reduced aeration favored anoxic phosphorus uptake, increasing the denitrifying phosphate assimilation potential from 18 to 41%. The membrane fouling rate increased from 1.02 to 4.81 kPa d⁻1 as aeration decreased, mainly due to diminished shear forces, soluble microbial products accumulation (+ 205%), floc size reduction (− 50.1%), and higher capillary suction time (+ 123%). Owing to the short current application (1.6 h d⁻1), the additional electrocoagulation cost was only 0.07 USD m⁻3, lower than values reported for continuous-flow EMBRs. Overall, operation of the SB-EMBR under reduced electric charge loading demonstrated promising energy efficiency while maintaining stable and satisfactory pollutant removal even at low aeration intensities.