A comprehensive evaluation of process kinetics: A plant-wide approach for nutrient removal and biogas production

BACKGROUND: Autotrophic microorganisms are quite vulnerable to environmental conditions and to inhibitory actions that would upset nitrification mechanisms. A reliable numerical assessment of the adverse impact is needed for proper remedial action. This study focused on the kinetic response of the nitrifying fraction within the activated sludge biomass under acute exposure to sulfamethoxazole (SMX), utilizing and emphasizing the role of enriched culture. A mixed culture sustained with an enrichment technique was used to generate oxygen uptake rate profiles, where ammonia was the sole substrate with different SMX concentrations.RESULTS: Model calibration studies yielded specific growth rates of 1.40/day for the ammonia oxidizing fraction and 0.65/day for the nitrite oxidizing fraction acting as the rate limiting step for the overall nitrification process. SMX did not appreciably affect the specific growth rates, but it induced a significant increase in half saturation coefficients. Moreover, increased endogenous decay rates were estimated.CONCLUSION: Model calibration values indicated that SMX induced competitive inhibition on microbial growth and enhanced endogenous respiration due to an increasing demand for the maintenance energy to activate antibiotic resistance. This underlines the merit of further studies on conditions to sustain resistant microorganisms capable of tolerating and even degrading antibiotics in biological systems.

Section: Discussionmentioning

confidence: 99%

Significance of enriched culture on the assessment of the acute inhibitory impact of sulfamethoxazole on nitrifying biomass

Katipoglu‐Yazan

Çokgör

Orhon

2022

“…The magnitude of b ⊘ A was reported in the range of 0.27-0.44/day in related literature. 12,[21][22][23][24][25] An experimental study on the Ambarlı sewage determined b ⊘ A as 0.36/day; a recent modeling study on Istanbul sewage based on experimental assessment, Insel et al 14 suggested a design value of 0.65/day for b ⊘ A at 20 °C; using the related temperature coefficient, ⊔ of 1.07, this value would correspond to 0.46/day at 15 °C.…”

Section: Nitrificationmentioning

confidence: 99%

“…This approach involving the accord between experimental data and system modeling is well demonstrated in the literature. [14][15][16][17] Rainwater intrusion and mixing with sewage in the influent stream before treatment also should be recognized as an equally significant issue. Aside from the increase in the treated flow rate under wet weather conditions, runoff mixing modifies the magnitude of selected design parameters and the pollutant loads.…”

Section: Introductionmentioning

confidence: 99%

Impact of rainwater intrusion on wastewater characterization and performance of nutrient removal activated sludge process

Orhon,

Hallaç,

Solmaz

et al. 2023

BackgroundThe paper investigated the negative impact of rainwater intrusion and mixing with sewage, on the operation of an existing nutrient removal activated sludge plant. It evaluated the magnitude of observed changes, both in terms of flow increase and modification of major parameters, together with the resulting impact on system performance. The study was carried out on a selected plant. The influent characteristics of the plant have been reviewed for 2021 and 2022, both for the dry and rainy periods. Collected data were evaluated together with the experimental support derived from the selected plant.ResultsStatistical assessment of the collected data revealed significant changes likely to affect the performance of the existing plant: Sewage flow was increased from 580,000 m3/d to 670,000 m3/d. While COD and total N were slightly reduced, a higher level of inorganic solids was observed. Assessment of nitrification‐denitrification processes yielded an aerobic sludge age, θXA of 9 d and a total sludge age, θX of 15 d, with a VD/VT ratio of 0.4. Solids mass balance indicated a biomass level of 6,100 mg/L with 47% of fixed solids, which was increased to 7,300 mg/L with 52% fixed solids with the wet weather flow. These values denoted reactor volume limitation for sustainable/safe operation.ConclusionAside from the impact of substantial treatment cost increase due to the incremental flow of 13.7 million m3/year at wet weather periods, control and decrease of inorganic solids emerged as the key issue to safeguard system operation. The study also indicated clues for diverting runoff mixing as a tangible remedial action.This article is protected by copyright. All rights reserved.

“…It should be noted that this parameter does not completely describe the sequencing batch reactor configuration operated in a temporal mode, where an effective sludge age, ⊔ XE , becomes applicable involving only the aerobic and anoxic fractions of the total cycle time, with the assumption that no biological reactions would occur during the idle period of the cycle. 46 A similar ⊔ XE concept may be used, if needed, for an activated sludge system designed for simultaneous nitrogen and phosphorus removal and accounting for the biomass fraction in the anaerobic reactor, 47 since ⊔ X would exclude the biomass fraction in the anaerobic tank devoted to phosphorus release and intra cellular storage of biopolymers. 48,49 Nitrification kinetics Nitrification has attracted attention since the discovery of the activated sludge process, mainly due to the additional oxygen demand created in the aeration tank and in the receiving waters.…”

Section: Sludge Agementioning

confidence: 99%

Role of experimental support as an essential component of sustainable design of the activated sludge process for nitrogen removal

Orhon

Hallaç²,

Kurt³

et al. 2022

Background This study evaluated the essential role of the experimental support as an integral component of process design for the nitrogen removal activated sludge process. This role was demonstrated in prescribing and implementing a relevant design procedure; a similar treatment plant at Ambarlı in Istanbul was selected to provide the necessary experimental support, which was derived from the sewage, lab‐scale experiments, and from the plant itself. Each step of the design included the relevant scientific and conceptual basis and was implemented using the necessary experimental data specifically generated from a selected wastewater source. Results The target was to compile experimental data that would be necessary for the study and be equally applicable to similar design or research activities elsewhere. This data included major wastewater characteristics, chemical oxygen demand (COD) fractionation, process kinetics for COD removal and nitrification, applicable sewage temperature, and details for the impact of primary settling on system performance. Conclusion This study developed a new design approach involving solely COD for both the substrate and biomass but expressing the related component per unit flow rate. This approach offered a template that is adjustable to any similar design by only requiring specific information on the sewage flow and sludge age. The entire design procedure was presented as supported by original experimental data and in a summarized algorithm format. The study also emphasized the selection of an appropriate anoxic volume. A revised empirical expression was suggested for the computation of the corresponding denitrification potential, which was also supported by process modelling; they both indicated that the current empirical approach generally defined an excessively large anoxic volume. © 2022 Society of Chemical Industry (SCI).