Key Takeaways & Executive Findings
- •• • O3-MNBs pre-oxidation achieved >97.5% removal of 2-MIB and GSM at 400 ng·L−1 within 30 min, and 67.2% algal cell removal, enabling compliance with the 10 ng·L−1 regulatory limit. • • When used as a deep treatment stage, O3-MNBs oxidation rate constants (k) were 10.1%–25.6% higher than in pre-oxidation, due to reduced background organic matter competition, maximizing degradation efficiency. • • PAC adsorption of GSM showed ~20.0% higher equilibrium capacity than 2-MIB, but raw water NOM reduced adsorption capacity by 6.0%–10.0%, necessitating dose optimization to ensure 2-MIB removal. • • Both oxidation and adsorption processes were accurately described by pseudo-first-order (R²>0.95) and pseudo-second-order (R²>0.99) kinetics, respectively, enabling model-driven prediction of oxidation time and PAC dosage for cost-effective operation.
Abstract
Algal-derived taste and odor compounds (2-methylisoborneol, 2-MIB, and geosmin, GSM) in drinking water sources are poorly removed by conventional treatment. This study systematically evaluated the standalone and combined performance of ozone micro-nano bubbles (O3-MNBs) oxidation and powdered activated carbon (PAC) adsorption for removing 2-MIB, GSM, and algal cells from source water. Results showed that O3-MNBs pre-oxidation achieved >97.5% removal of odorants at 400 ng·L−1 and 67.2% algal cell removal within 30 min. When applied as a deep treatment stage, the degradation rate constant (k) was 10.1%–25.6% higher than in pre-oxidation due to lower background matrix interference. Both pre-oxidation and deep treatment reduced effluent concentrations of 2-MIB and GSM to below 10 ng·L−1, with oxidation kinetics fitting pseudo-first-order models (R²>0.95). PAC adsorption of both compounds followed pseudo-second-order kinetics (R²>0.99), with GSM equilibrium adsorption capacity approximately 20.0% higher than that of 2-MIB. In pure water, adsorption capacity increased by >10.0% compared to raw water. Based on kinetic models, a quantitative prediction method was established for O3-MNBs oxidation and PAC adsorption processes, aiming to achieve efficient odorant removal and cost optimization, providing theoretical support for advanced drinking water purification and smart water plant construction.
1. Introduction
Conventional drinking water treatment processes—coagulation, sedimentation, and filtration—exhibit limited removal of algal-derived taste and odor compounds such as 2-methylisoborneol (2-MIB) and geosmin (GSM). These low-molecular-weight, chemically stable compounds often persist at ng·L−1 levels, failing to meet the stringent 10 ng·L−1 regulatory limit set by the 2022 Chinese Drinking Water Standard (GB 5749—2022). Furthermore, algal cells can penetrate filters, releasing intracellular odorants and organic matter, exacerbating treatment challenges. Advanced oxidation and adsorption processes are therefore required to address this bottleneck.
Ozone micro-nano bubble (O3-MNBs) technology offers enhanced mass transfer and radical utilization compared to conventional ozonation, while powdered activated carbon (PAC) provides high adsorption capacity for dissolved odorants. However, the synergistic behavior of O3-MNBs oxidation followed by PAC adsorption, particularly under varying water quality conditions, has not been systematically quantified. This study bridges that gap by evaluating the standalone and combined performance of O3-MNBs and PAC, establishing kinetic models for both processes, and proposing a model-driven approach to optimize oxidation time and PAC dosage for cost-effective odor control in drinking water treatment.
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DENG Qiujin, LU Zhifeng, CHEN Ben, CHEN Sa, LIANG Qifeng, SONG Chuqi, YANG Qiujian, JIA Yanyan, LYU Hui (2026). Combined Ozone Micro-Nano Bubble Oxidation and Powdered Activated Carbon Adsorption for Removal of Taste and Odor Compounds from Drinking Water. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202507110
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Frequently Asked Questions
What is the impact of natural organic matter (NOM) on the adsorption capacity of powdered activated carbon (PAC) for 2-MIB and GSM?
NOM in raw water competitively inhibits adsorption, reducing the equilibrium adsorption capacity (qe) by 6.0%–10.0% compared to pure water. This reduction necessitates higher PAC dosages in real water matrices to achieve the same removal efficiency, particularly for 2-MIB which has lower affinity than GSM.
How does the placement of O3-MNBs oxidation (pre-oxidation vs. deep treatment) affect the degradation kinetics of odorants?
When applied as a deep treatment stage after conventional processes, the background matrix (e.g., NOM) is lower, leading to a 10.1%–25.6% increase in the pseudo-first-order rate constant (k) compared to pre-oxidation. This allows faster degradation of 2-MIB and GSM, achieving effluent concentrations below 10 ng·L−1 within shorter contact times.
What are the kinetic models that describe the oxidation and adsorption processes, and how can they be used for process design?
Oxidation of 2-MIB and GSM by O3-MNBs follows pseudo-first-order kinetics (R²>0.95), while PAC adsorption follows pseudo-second-order kinetics (R²>0.99). These models allow prediction of required oxidation time and PAC dosage for target effluent concentrations, enabling cost optimization and real-time process control in water treatment plants.
What is the removal efficiency of algal cells by O3-MNBs pre-oxidation, and why is this important?
O3-MNBs pre-oxidation achieved 67.2% algal cell removal within 30 minutes. This is critical because algal cells can release intracellular odorants and organic matter if not lysed, and their removal reduces the load on downstream processes and minimizes the risk of taste and odor episodes.
How does the adsorption capacity of PAC for GSM compare to that for 2-MIB, and what are the implications for treatment?
GSM exhibits approximately 20.0% higher equilibrium adsorption capacity on PAC than 2-MIB. This means that for a given PAC dose, GSM is removed more effectively, while 2-MIB may require higher PAC dosages or additional treatment to meet the 10 ng·L−1 standard, particularly during algal bloom events when 2-MIB concentrations can spike.
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