Modeling acute impact of sulfamethoxazole on the utilization of simple and complex substrates by fast growing microbial culture

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BACKGROUND The study focused on the biodegradation of pretreated olive mill wastewater (OMW) properly diluted in and mixed with a biodegradable substrate and/or domestic sewage stream. It utilized the permeate of a chemically conditioned two‐stage ultrafiltration/nanofiltration system with COD of 5700 mg L−1 and a total phenol content of 100 mg L−1. Peptone mixture with similar characteristics to domestic sewage was adopted as the biodegradable synthetic substrate. The study relied on two sets of microbial culture; one acclimated to peptone and the other to a mixture of peptone and domestic sewage. Respirometric analyses were conducted on pretreated OMW diluted in the selected substrate using corresponding biomass seeding. RESULTS Model evaluation of the oxygen uptake rate profiles indicated that the pretreated OMW was fully consumed in the respirometric tests. There were no inhibitory/toxic impacts of OMW dosing on the biomass. The entire biomass participated in the utilization of OMW/substrate with no metabolic adjustment problems. CONCLUSION Experimental results provided conclusive evidence that co‐treatment with a domestic sewage stream is a viable option for OMW management, after a chemically conditioned two‐stage filtration used as the pretreatment step. Pretreatment removes the recalcitrant nature of the wastewater, which becomes fully biodegradable under appropriate dilution and mixing conditions. © 2016 Society of Chemical Industry

Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Biodegradation of pretreated olive mill effluent in mixture with a domestic sewage or compatible wastewater stream

Khaligh

Yağcı

Ubay‐Cokgor

et al. 2016

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“…In conventional inhibition kinetics, the increase in half saturation coefficients are classified as competitive inhibition based upon enzyme analogy . (ii) Significant increase in the endogenous decay rate from 0.12 day ‐1 in the control reactor to 0.25 day ‐1 upon first exposure to SMX both for nitrifiers and heterotrophic biomass: this increase was previously reported for heterotrophic biomass under acute impact of SMX . Exposure to antibiotics activates a defense mechanism, which requires higher maintenance energy.…”

Section: Resultsmentioning

confidence: 99%

“…However, lab scale treatment systems operated with specific operational conditions have achieved partial degradation and co‐metabolism of SMX. The adverse effects of SMX were mainly investigated with the comparison of process kinetics and the change of microbial composition in carbon removal systems where the microbial community was dominated by heterotrophic bacteria . However, research on the impact of SMX on the nitrification mechanism is limited to a few studies …”

Section: Introductionmentioning

confidence: 99%

Chronic impact of sulfamethoxazole: how does process kinetics relate to metabolic activity and composition of enriched nitrifying microbial culture?

Katipoglu‐Yazan

Ubay‐Cokgor

Orhon

2018

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BACKGROUND This study investigated utilization kinetics of ammonia‐nitrogen induced by chronic sulfamethoxazole (SMX) exposure on biomass with an enriched nitrifying community. A lab‐scale activated sludge system was supplied with 100 mg COD L‐1 of peptone mixture and 50 mg N L‐1 of ammonia nitrogen at a SRT of 15 days. At steady‐state, the reactor was operated with additional daily SMX dosing of 50 mg L‐1 for 35 days. Profiles of oxygen uptake rates and nitrogen fractions obtained in respirometric/batch experiments were used for estimation of nitrification kinetics. RESULTS Acute inhibitory impact of SMX was expressed with high levels of half saturation constants and endogenous decay rates. After 35 days, half saturation constants significantly increased while higher active biomass fractions and recovered endogenous decay rates were estimated. At the end of the acclimation phase, 92% nitrification was achieved with 10 mg L‐1 SMX utilization. CONCLUSION Interpretation of modeling results with the outcomes of molecular analysis facilitated explanation of autotrophic/heterotrophic bacteria behavior in the course of SMX exposure. Removal of SMX may be attributed to co‐metabolism with ammonia oxidation and/or activity of SMX utilizing heterotrophic bacteria. © 2017 Society of Chemical Industry

“…The AQUASIM software was used for model simulations . Execution of the simulation methodology was described in detail elsewhere , . As specified before, the two processes, i.e.…”

Section: Methodsmentioning

confidence: 99%

A novel modeling approach for evaluating microbial mechanism and design of contact stabilization process

Allı

İnsel

Sözen

et al. 2017

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BACKGROUND The paper offers a novel interpretation of microbial mechanisms and evaluates the assets of contact stabilization (CS) using multi‐component modelling. A model structure re‐defining microbial processes is adopted, where the function of the contact tank was limited to the utilization of soluble substrate fractions and that of the stabilization tank essentially involved endogenous decay and removal of the adsorbed particulate substrate. RESULTS The model was used to simulate the microbial behaviour and performance of CS in comparison with a conventional activated sludge system (CAS), at an SRT range between 6 and 15 d. The results were confirmed by a stoichiometric description of the process using relevant mass balance relationships, which identified the role of major parameters in system behaviour and performance. A rational process design procedure was proposed based on modelling and process stoichiometry. CONCLUSION The CS process achieved effective carbon removal with a much smaller footprint and/or aeration volume with respect to CAS, due to its ability to work at significantly higher volumetric organic loadings; its flexibility to be operated at much higher SRT compared with CAS with the same HRT, allowed minimizing sludge production and sustaining a microbial composition also supporting nitrification. However, process stoichiometry reflected that the CS process, despite its significant advantages, should not be considered a suitable candidate for maximizing sludge harvest and energy recovery. © 2017 Society of Chemical Industry