Increasing oxygen transfer efficiency through sorption enhancing strategies

Garrido-Baserba, Manel; Rosso, Diego; Odize, Victory; Rahman, Arifur; Winckel, Tim Van; Novak, John T.; Al‐Omari, Ahmed; Murthy, Sudhir; Stenstrom, Michael K.; Clippeleir, Haydée De

doi:10.1016/j.watres.2020.116086

Cited by 10 publications

(4 citation statements)

References 63 publications

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“…This could include calculation of OUR in situ, based on applied airflow rates, or by applying intermittent aeration. The latter approaches were applied in other studies to improve nitrogen removal (Baeza et al, 2002; Jubany et al, 2009; Surmacz‐Gorska et al, 1996), but never tested for HRAS where faster OUR rates and more dynamics in oxygen transfer rates might exist (Garrido‐Baserba et al, 2020). Alternatively, other factors that can detect the feast famine level and microbial response similar to OUR might result in the same level of bioflocculation limitation detection.…”

Section: Resultsmentioning

confidence: 99%

“…This result confirmed the need for dynamic wasting targets in the function of bioflocculation conditions to achieve more controlled outputs in terms of effluent quality. The achieved better bioflocculation could potentially reduce energy demand through better sorption of colloids and surfactants (Garrido-Baserba et al, 2020), which can further enhance the energy mass balance of the high-rate CS system. In addition, good and stable effluent quality also created increased stability for downstream nutrient removal processes as more stable effluent COD/N ratios were established.…”

Section: Our Control With Bioflocculation Boundaries (Scenario B): Fu...mentioning

confidence: 99%

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Introducing bioflocculation boundaries in process control to enhance effluent quality of high‐rate contact‐stabilization systems

Ngo

Tampon

Winckel

et al. 2022

Water Environment Research

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High‐rate activated sludge (HRAS) systems suffer from high variability of effluent quality, clarifier performance, and carbon capture. This study proposed a novel control approach using bioflocculation boundaries for wasting control strategy to enhance effluent quality and stability while still meeting carbon capture goals. The bioflocculation boundaries were developed based on the oxygen uptake rate (OUR) ratio between contactor and stabilizer (feast/famine) in a high‐rate contact stabilization (CS) system and this OUR ratio was used to manipulate the wasting setpoint. Increased oxidation of carbon or decreased wasting was applied when OUR ratio was <0.52 or >0.95 to overcome bioflocculation limitation and maintain effluent quality. When no bioflocculation limitations (OUR ratio within 0.52–0.95) were detected, carbon capture was maximized. The proposed control concept was shown for a fully automated OUR‐based control system as well as for a simplified version based on direct waste flow control. For both cases, significant improvements in effluent suspended solids level and stability (<50‐mg TSS/L), solids capture over the clarifier (>90%), and COD capture (median of 32%) were achieved. This study shows how one can overcome the process instability of current HRAS systems and provide a path to achieve more reliable outcomes. Practitioner points Online bioflocculation boundaries (upper and lower limit) were defined by the OUR ratio between contactor and stabilizer (feast/famine). To maintain effluent quality, carbon oxidation was minimized when bioflocculation was not limited (0.52–0.95 OUR ratio) and increased otherwise. A fully automated control concept was piloted, also a more simplified semiautomated option was proposed. Wasting control strategies with bioflocculation boundaries improved effluent quality while meeting carbon capture goals. Bioflocculation boundaries are easily applied to current wasting control schemes applied to HRAS systems (i.e., MLSS, SRT, and OUR controls).

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Section: Resultsmentioning

confidence: 99%

Section: Our Control With Bioflocculation Boundaries (Scenario B): Fu...mentioning

confidence: 99%

Introducing bioflocculation boundaries in process control to enhance effluent quality of high‐rate contact‐stabilization systems

Ngo

Tampon

Winckel

et al. 2022

Water Environment Research

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“…This can have a positive effect on oxygen transfer as substances inhibiting gas-transfer at the bubble-bulk interface are removed or adsorbed on sludge flocs. Garrido-Baserba et al [19] discussed strategies to increase oxygen transfer efficiency through biosorption, inter alia by specifically removing surfactants. The amphiphilic structure of surfactants causes a negative effect on oxygen transfer at low concentrations in clean water [20] and activated sludge [21].…”

Section: Influences On Oxygen Transfer In Two-stage Activated Sludge ...mentioning

confidence: 99%

Oxygen Transfer in Two-Stage Activated Sludge Wastewater Treatment Plants

Schwarz

Behnisch

Trippel

et al. 2021

Water

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Aeration is an energy-intensive process of aerobic biological treatment in wastewater treatment plants (WWTP). Two-stage processes enable energy-efficient operation, but oxygen transfer has not been studied in depth before. In this study, α-factors were determined with long-term ex situ steady-state off-gas measurements in pilot-scale test reactors (5.8 m height, 8.3 m3) coupled to full-scale activated sludge basins. A two-stage WWTP with more than 1 Mio population equivalent was studied over 13 months including rain and dry weather conditions. Operating data, surfactant concentrations throughout the two-stage process, and the effect of reverse flexing on pressure loss of diffusers were examined. The values of αmean, αmin, and αmax for design load cases of aeration systems were determined as 0.45, 0.33, and 0.54 in the first high-rate carbon removal stage and as 0.80, 0.69, and 0.91 in the second nitrification stage, respectively. The first stage is characterized by a distinct diurnal variation and decrease in α-factor during stormwater treatment. Surfactants and the majority of the total organic carbon (TOC) load are effectively removed in the first stage; hence, α-factors in the second stage are higher and have a more consistent diurnal pattern. Proposed α-factors enable more accurate aeration system design of two-stage WWTPs. Fouling-induced diffuser pressure loss can be restored effectively with reverse flexing in both treatment stages.

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“…To enhance nitrogen removal capacity, the BNR waste flow, enriched with nitrifiers, was seamlessly recycled to the A stage for bioaugmentation. This approach is not only cost‐effective with minimal retrofitting, but there is also no requirement for building up a separate sidestream nitrifier system (Bailey et al, 2008; Garrido‐Baserba et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Case study: Bioaugmenting the comammox dominated biomass from B‐stage to enhance nitrification in A‐stage at Blue Plains AWWTP

Nguyen Quoc,

Peng,

De Clippeleir

et al. 2024

Water Environment Research

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A comprehensive case study was undertaken at the Blue Plains wastewater treatment plant (WWTP) to explore the bioaugmentation technique of introducing nitrifying sludge into the non‐nitrifying stage over the course of two operational years. This innovative approach involved the return of waste activated sludge (WAS) from the biological nutrient removal (BNR) system to enhance the nitrification in the high carbon removal rate system. The complete ammonia oxidizer (comammox) Nitrospira Nitrosa was identified as the main nitrifier in the system. Bioaugmentation was shown to be successful as nitrifiers returned from BNR were able to increase the nitrifying activity of the high carbon removal rate system. There was a positive correlation between returned sludge from the BNR stage and the specific total kjeldahl nitrogen (TKN) removal rate in A stage. The bioaugmentation process resulted in a remarkable threefold increase in the specific TKN removal rate within the A stage. Result suggested that recycling of WAS is a simple technique to bio‐augment a low SRT system with nitrifiers and add ammonia oxidation to a previously non‐nitrifying stage. The results from this case study hold the potential for applicable implications for other WWTPs that have a similar operational scheme to Blue Plains, allowing them to reuse WAS from the B stage, previously considered waste, to enhance nitrification and thus improving overall nitrogen removal performance.Practitioner Points Comammox identifying as main nitrifier in the B stage. Comammox enriched sludge from B stage successfully bio‐augmented the East side of A stage up to threefold. Bioaugmentation of comammox in the West side of A stage was potentially inhibited by the gravity thickened overflow. Sludge returned from B stage to A stage can improve nitrification with a very minor retrofits and short startup times.

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Increasing oxygen transfer efficiency through sorption enhancing strategies

Cited by 10 publications

References 63 publications

Introducing bioflocculation boundaries in process control to enhance effluent quality of high‐rate contact‐stabilization systems

Introducing bioflocculation boundaries in process control to enhance effluent quality of high‐rate contact‐stabilization systems

Oxygen Transfer in Two-Stage Activated Sludge Wastewater Treatment Plants

Case study: Bioaugmenting the comammox dominated biomass from B‐stage to enhance nitrification in A‐stage at Blue Plains AWWTP

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