Editorial: Status and future of wastewater treatment modelling

Rieger, Leiv; Takács, I.; Shaw, Andy; Ohtsuki, T.; Langergraber, Günter; Gillot, S.

doi:10.2166/wst.2010.003

Cited by 13 publications

(13 citation statements)

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“…Consequently, our results convincingly show that the level of inhibition on N 2 O reduction is strongly correlated with the H 2 S concentration rather than the sulfide. Usually, in the presence of a competitive inhibitor, the maximum enzyme activity can still be reached if sufficient substrate is available. , However, in all Set I batch tests, although the initial N 2 O concentration was substantially in excess, the N 2 O reduction rate measured in Step II (in the presence of H 2 S) was always lower than that in Step I (in the absence of H 2 S), which suggested that inhibition was not competitive inhibition. In contrast, a noncompetitive-type inhibition model , was found to describe the experimental data well, which suggests that H 2 S inhibition on N 2 O reduction was likely due to noncompetitive inhibition.…”

Section: Resultsmentioning

confidence: 94%

Effect of H₂S on N₂O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Pan¹,

Ye²,

Yuan³

2013

Environ. Sci. Technol.

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Sulfide is produced in sewer networks, and previous studies suggest that sulfide in sewage could alter the activity of heterotrophic denitrification and lead to N2O accumulation during biological wastewater treatment. However, the details of this phenomenon are poorly understood. In this study, the potential inhibitory effects of sulfide on nitrate, nitrite, and N2O reduction were assessed with a methanol-utilizing denitrifying culture both prior to and after its exposure and adaptation to sulfide. Hydrogen sulfide was found to be strongly inhibitory to N2O reduction, with 50% inhibition observed at H2S concentrations of 0.04 mg H2S-S/L and 0.1 mg H2S-S/L for the unadapted and adapted cultures, respectively. In comparison, both nitrate and nitrite reduction was more tolerant to H2S. A 50% inhibition of nitrite reduction was observed at approximately 2.0 mg H2S-S/L for both unadapted and adapted cultures, while no inhibition of nitrate reduction occurred at the highest H2S concentrations applied (2.0 mg H2S-S/L) to either culture. N2O accumulation was observed during nitrate and nitrite reduction by the adapted culture when H2S concentrations were above 0.5 and 0.2 mg H2S-S/L, respectively. Additionally, we reveal that hydrogen sulfide (H2S), rather than sulfide, was likely the true inhibitor of N2O reduction, and the inhibitory effect was reversible. These findings suggest that sulfide management in sewers could potentially have a significant impact on N2O emission from wastewater treatment plants.

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Section: Resultsmentioning

confidence: 94%

Effect of H₂S on N₂O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Pan¹,

Ye²,

Yuan³

2013

Environ. Sci. Technol.

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“…That said, it is important to point out that calculations in Table 3 were made from experimental data values not beyond than ≈ 2 , therefore, without considering the entire tail of the RTD. The differences calculated between both configurations based on these parameters would have been lower if RTD tails had been taken into account [31].…”

Section: Rheological Propertiesmentioning

confidence: 99%

Biological reactor retrofitting using CFD-ASM modelling

Climent

Basiero²,

Martínez‐Cuenca

et al. 2018

Chemical Engineering Journal

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In recent years, the interest on modelling activated sludge (AS) systems by means of Computational Fluid Dynamics (CFD) techniques has significantly increased. This work shows a successful case study combining CFD hydrodynamics and biokinetic modelling. The hydrodynamics is analysed by using the Reynolds-averaged Navier-Stokes equation for incompressible non-Newtonian fluids and SST turbulence model. Biokinetics has been included into the CFD as transport equations with source and sink terms defined by the Activated Sludge Model nº1 (ASM1). Furthermore, a strategy for reducing the computational cost while maintaining accuracy of the results of these calculations has been proposed. This strategy is based on a two-step solver configuration and the definition of a variable timestep scheme. The resulting CFD-ASM approach permits a proper evaluation of denitrification in the anoxic tanks as well as the reproduction of nitrate and readily biodegradable substrate distributions. To demonstrate the strength of the proposed CFD-ASM, it has been used to evaluate the operation of a full-scale AS system and optimize its performance through changes in the biological reactor anoxic zone. The original configuration has been retrofitted and modified after detecting intrinsic defects on the fluid behaviour within the tank. This study has been assessed by analysing hydrodynamics in detail and validating the simulation results with tracer tests and flow velocity measurements. Substantial variations on the Residence Time Distribution have been confirmed when modifying the internal elements of the tank configuration: the wall-bushing and the stirrer positioning. As a result of this work, an influential short circuiting was corrected improving hydrodynamics and increasing mean residence time, all favouring denitrification efficiency. Outcomes of this study show the benefit of CFD when applied to AS tanks.

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“…It could be especially useful to identify consistent relationships among characteristics not only for individual cities, but also across regions, which would provide another way to increase accuracy of predictions while reducing costs (Englund et al, 2020). For example, the planning and design of municipal wastewater treatment plants, relations like VSS/TSS ratio of 0.74-0.85 for untreated wastewater are commonly assumed (Rieger et al, 2012;Tchobanoglous et al, 2014). As shown in Figure 6A, in this study a strong correlation between VS and TS (R 2 = 0.88) with a slope of 0.52 was observed with data from all seven countries.…”

Section: Qualities: Comparison Of Fecal Sludge Characteristics In Sev...mentioning

confidence: 99%

Quantities and qualities of fecal sludge: Experiences from field implementation with a Volaser in 7 countries during a pandemic

et al. 2023

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Reasonable estimates for quantities and qualities (Q&Q) of fecal sludge that accumulate in onsite sanitation containments are fundamental for the design of appropriate management and treatment solutions, from community to city-scale. There are increasing attempts to improve Q&Q estimates, but current approaches are still at a conceptual level, and are not yet standardized with confirmed statistical relationships. To reach this level, we will need consistent approaches for planning, measuring, and global collaborations. Hence, the objectives of this study were: (1) to assess and compare Q&Q of fecal sludge from seven cities and communities, and explore statistical relationships that could be used to increase accuracy of Q&Q estimations; (2) to test and launch the Volaser device for measuring in situ volumes of fecal sludge; and (3) to capture lessons learned from field implementation with collaborators in seven countries during a global pandemic when no international travel was possible. The study took place in Ghana, India, Lebanon, Kenya, Sierra Leone, Uganda, and Zambia during the COVID-19 pandemic. Q&Qs were measured in 204 containments with a Volaser, laboratory analysis, and questionnaire. Results indicate that there are differences in Total Solids (TS) and Chemical Oxygen Demand (COD) in fecal sludge based on containment type, toilet type, source, and whether there is a water connection on the premises. Based on the results of this study, together with previously published open-source data, an empirical relationship for Volatile Solids (VS) and TS of 0.49 (R2 = 0.88) was established using 1,206 data points. For COD/TS, no significant relationship was observed. Developing such empirical relationships will be useful for planning and modeling approaches. An external evaluation was conducted to evaluate overall project management, Volaser technology transfer, and effects of collaborating during the COVID-19 pandemic. Success factors for collaborating with new and existing partners without face-to-face meetings included laboratory capacity and experience with analytical methods, study objectives that were relevant for the partner and locality, and a strong quality assurance plan to ensure comparability of results. The lessons learned can be taken forward as ways to reduce carbon footprint, and contribute to resilient, inclusive development research projects.

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Editorial: Status and future of wastewater treatment modelling

Cited by 13 publications

References 1 publication

Effect of H₂S on N₂O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Effect of H₂S on N₂O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Biological reactor retrofitting using CFD-ASM modelling

Quantities and qualities of fecal sludge: Experiences from field implementation with a Volaser in 7 countries during a pandemic

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Editorial: Status and future of wastewater treatment modelling

Cited by 13 publications

References 1 publication

Effect of H2S on N2O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Effect of H2S on N2O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Biological reactor retrofitting using CFD-ASM modelling

Quantities and qualities of fecal sludge: Experiences from field implementation with a Volaser in 7 countries during a pandemic

Contact Info

Product

Resources

About

Effect of H₂S on N₂O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers

Effect of H₂S on N₂O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers