Assessing the effects of intra-granule precipitation in a full-scale industrial anaerobic digester

2019 ◽  
Vol 79 (7) ◽  
pp. 1327-1337 ◽  
Author(s):  
H. Feldman ◽  
X. Flores-Alsina ◽  
P. Ramin ◽  
K. Kjellberg ◽  
U. Jeppsson ◽  
...  
Keyword(s):  
Energy Recovery ◽  
Granular Sludge ◽  
Full Scale ◽  
Scale Model ◽  
Ph Gradients ◽  
Operational Conditions ◽  
Reject Water ◽  
Biomass Activity ◽  
Multiple Mineral

Abstract In this paper, a multi-scale model is used to assess the multiple mineral precipitation potential in a full-scale anaerobic granular sludge system. Reactor behaviour is analysed under different operational conditions (addition/no addition of reject water from dewatering of lime-stabilized biomass) and periods of time (short/long term). Model predictions suggest that a higher contribution of reject water promotes the risk of intra-granule CaCO3 formation as a result of the increased quantity of calcium arriving with that stream combined with strong pH gradients within the biofilm. The distribution of these precipitates depends on: (i) reactor height; and (ii) granule size. The study also exposes the potential undesirable effects of the long-term addition of reject water (a decrease in energy recovery of 20% over a 100-day period), caused by loss in biomass activity (due to microbial displacement), and the reduced buffer capacity. This demonstrates how both short-term and long-term operational conditions may affect the formation of precipitates within anaerobic granules, and how it may influence methane production and consequently energy recovery.

scholarly journals Model assisted identification of N2O mitigation strategies for full-scale reject water treatment plants

2021 ◽  
Author(s):  
M. Beier ◽  
I. Feldkämper ◽  
A. Freyschmidt
Keyword(s):  
Water Treatment ◽  
High Strength ◽  
Full Scale ◽  
Mitigation Strategies ◽  
N2o Emissions ◽  
N2o Formation ◽  
Operational Conditions ◽  
Reject Water ◽  
Batch Tests ◽  
Measurement Campaigns

Abstract In a 3-year research project, a new approach to forecast biological N2O formation and emission at high-strength reject water treatment has been developed (ASM3/1_N2OISAH). It was calibrated by extensive batch-tests and finally evaluated by long-term measurement campaigns realized at three WWTPs with different process configurations for nitrogen removal of reject water. To enable a model application with common full-scale data, the nitritation connected supplementary processes are not depicted in the model. Instead, within the new model approach the N2O formation is linked to the NH4-N oxidation rate by defining specific formation factors [N2O-Nform/NH4-Nox], depending on three minor parameters, the concentrations of NO2 and O2 as well as the NH4 load. A comparison between the measured and the modeled N2O concentrations in the liquid and gas phase at the full-scale treatment plants prove the ability of the proposed modelling approach to represent the observed trends of N2O formation, emission and reduction using the standard parameter set of kinetics and formation factors. Thus, enabling a reliable estimation of the N2O emissions for different operational conditions. The measurements indicate that a formation of N2O by AOB cannot completely be avoided. However, a considerable reduction of the formed N2O was observed in an anoxic environment. Applying the model, operational settings and mitigation strategies can now be identified without extensive measurement campaigns. For further enhancement of the model, first results for kinetics of N2O reduction kinetics by denitrification processes were determined in laboratory-scale batch tests.

Mineral oil bio-degradation within a permeable pavement: long term observations

1999 ◽  
Vol 39 (2) ◽  
pp. 103-109 ◽  
Author(s):  
C. J. Pratt ◽  
A. P. Newman ◽  
P. C. Bond
Keyword(s):  
Water Quality ◽  
Microbial Population ◽  
Mineral Oil ◽  
Full Scale ◽  
Hydrocarbon Contamination ◽  
Scale Model ◽  
Research Project ◽  
Permeable Pavement

The paper reports on the first 300 days of a research project conducted at Coventry University, which has focused on the ability of a permeable pavement, reservoir structure to retain and treat petroleum-derived pollutants through in situ microbial bio-degradation. The research has required the construction of a full-scale model permeable pavement in the laboratory, which has been subjected to prolonged low-level hydrocarbon contamination, representative of typical loadings to urban surfaces such as highways and car parks. Water quality and bio-degradation indicators have been monitored over several months so that the capability of the permeable pavement to maintain a viable and effective microbial population could be assessed. The research has demonstrated that the structure can be used as an effective in situ aerobic bioreactor.

Effect of mesh on CFD aerodynamic performances of a container ship

2020 ◽  
Vol 20 (3) ◽  
pp. 343-353
Author(s):  
Ngo Van He ◽  
Le Thi Thai
Keyword(s):  
Water Surface ◽  
Reference Model ◽  
Full Scale ◽  
Scale Model ◽  
Container Ship ◽  
Ansys Fluent ◽  
Remarkable Effect ◽  
Aerodynamic Performances ◽  
Mesh Convergence

In this paper, a commercial CFD code, ANSYS-Fluent has been used to investigate the effect of mesh number generated in the computed domain on the CFD aerodynamic performances of a container ship. A full-scale model of the 1200TEU container ship has been chosen as a reference model in the computation. Five different mesh numbers for the same dimension domain have been used and the CFD aerodynamic performances of the above water surface hull of the ship have been shown. The obtained CFD results show a remarkable effect of mesh number on aerodynamic performances of the ship and the mesh convergence has been found. The study is an evidence to prove that the mesh number has affected the CFD results in general and the accuracy of the CFD aerodynamic performances in particular.

scholarly journals Anaerobic hydrolysis of complex substrates in full-scale aerobic granular sludge: enzymatic activity determined in different sludge fractions

2021 ◽  
Author(s):  
Sara Toja Ortega ◽  
Mario Pronk ◽  
Merle K. de Kreuk
Keyword(s):  
Hydrolytic Enzymes ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Granular Sludge ◽  
Hydrolytic Activity ◽  
Full Scale ◽  
Aerobic Granular Sludge ◽  
Bulk Liquid ◽  
Granule Formation ◽  
Hydrolysis Of

Abstract Complex substrates, like proteins, carbohydrates, and lipids, are major components of domestic wastewater, and yet their degradation in biofilm-based wastewater treatment technologies, such as aerobic granular sludge (AGS), is not well understood. Hydrolysis is considered the rate-limiting step in the bioconversion of complex substrates, and as such, it will impact the utilization of a large wastewater COD (chemical oxygen demand) fraction by the biofilms or granules. To study the hydrolysis of complex substrates within these types of biomass, this paper investigates the anaerobic activity of major hydrolytic enzymes in the different sludge fractions of a full-scale AGS reactor. Chromogenic substrates were used under fully mixed anaerobic conditions to determine lipase, protease, α-glucosidase, and β-glucosidase activities in large granules (>1 mm in diameter), small granules (0.2–1 mm), flocculent sludge (0.045–0.2 mm), and bulk liquid. Furthermore, composition and hydrolytic activity of influent wastewater samples were determined. Our results showed an overcapacity of the sludge to hydrolyze wastewater soluble and colloidal polymeric substrates. The highest specific hydrolytic activity was associated with the flocculent sludge fraction (1.5–7.5 times that of large and smaller granules), in agreement with its large available surface area. However, the biomass in the full-scale reactor consisted of 84% large granules, making the large granules account for 55–68% of the total hydrolytic activity potential in the reactor. These observations shine a new light on the contribution of large granules to the conversion of polymeric COD and suggest that large granules can hydrolyze a significant amount of this influent fraction. The anaerobic removal of polymeric soluble and colloidal substrates could clarify the stable granule formation that is observed in full-scale installations, even when those are fed with complex wastewaters. Key points • Large and small granules contain >70% of the hydrolysis potential in an AGS reactor. • Flocculent sludge has high hydrolytic activity but constitutes <10% VS in AGS. • AGS has an overcapacity to hydrolyze complex substrates in domestic wastewater. Graphical abstract

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