Integration of complete elemental mass-balanced stoichiometry and aqueous-phase chemistry for bioprocess modelling of liquid and solid waste treatment systems − Part 2:  Bioprocess stoichiometry

Bioprocesses interact with the aqueous environment in which they take place. Integrated bioprocess and three-phase (aqueous−gas−solid) multiple strong and weak acid/base system models are currently being developed for a range of wastewater treatment applications including anaerobic digestion, biological sulphate reduction, autotrophic denitrification, biological desulphurization and plant-wide water and resource recovery facilities. In order to model, measure and control such integrated systems, a thorough understanding of the interactions between the bioprocesses and aqueous phase multiple strong and weak acid/bases are required. In the first of this series of five papers, the generalized procedure for deriving bioprocess stoichiometric equations was explained. This second paper presents the stoichiometric equations for the major biological processes and shows how their structure can be analysed to provide insight into how bioprocesses interact with the aqueous environment. Such insight is essential for confident, effective and reliable use of model development protocols and algorithms. It shows that the composite parameters, total oxygen demand (TOD, electron donating capacity) and alkalinity (proton accepting capacity), are conserved in bioprocess stoichiometry and their changes in the aqueous phase can be calculated from the bioprocess components. In the third paper, the measurement of the organics composition is presented. The link between the modelling and measurement frameworks of the aqueous phase, which uses the composite parameter alkalinity, is described in the fourth paper. Aqueous ionic speciation modelling is described in detail in the fifth.

Download Full-text

Integration of complete elemental mass-balanced stoichiometry and aqueous-phase chemistry for bioprocess modelling of liquid and solid waste treatment systems – Part 1: The physico-chemical framework

Water SA ◽

10.17159/wsa/2021.v47.i3.11857 ◽

2021 ◽

Vol 47 (3 July) ◽

Author(s):

CJ Brouckaert ◽

BM Brouckaert ◽

GA Ekama

Keyword(s):

Wastewater Treatment ◽

Aqueous Phase ◽

Waste Treatment ◽

Oxygen Demand ◽

Weak Acid ◽

Aqueous Environment ◽

Base System ◽

Reaction Stoichiometry ◽

Phase Chemistry ◽

And Control

Bioprocesses interact with the aqueous environment in which they take place. Currently integrated bioprocess and three-phase (aqueous–gas–solid) multiple strong and weak acid/base system models are being developed for a range of wastewater treatment applications, including anaerobic digestion, biological sulphate reduction, autotrophic denitrification, biological desulphurization and plant-wide wastewater treatment systems. In order to model, measure and control such integrated systems, a thorough understanding of the interaction between the bioprocesses and aqueous-phase multiple strong and weak acid/bases is required. This first in a series of five papers sets out a conceptual framework and methodology for deriving bioprocess stoichiometric equations. It also introduces the relationship between alkalinity changes in bioprocesses and the underlying reaction stoichiometry, which is a key theme of the series. The second paper develops the stoichiometric equations for the main biological transformations that are important in wastewater treatment. The link between the modelling and measurement frameworks, which uses summary measures such as chemical oxygen demand (COD) and alkalinity, is described in the third and fourth papers. The fifth paper describes an equilibrium aquatic speciation algorithm which can be combined with bioprocess stoichiometry to provide integrated models of wastewater treatment processes.

Download Full-text

Management of Dairy Waste in the Sonoran Desert Using Constructed Wetland Technology

Water Science & Technology ◽

10.2166/wst.1999.0136 ◽

1999 ◽

Vol 40 (3) ◽

pp. 57-65 ◽

Cited By ~ 6

Author(s):

Martin M. Karpiscak ◽

Robert J. Freitas ◽

Charles P. Gerba ◽

Luis R. Sanchez ◽

Eylon Shamir

Keyword(s):

Sonoran Desert ◽

Suspended Solids ◽

Waste Treatment ◽

Oxygen Demand ◽

Dairy Wastewater ◽

Chemical Parameters ◽

Treatment Facility ◽

Physical Chemical ◽

Scirpus Validus ◽

Surface Wetland

An integrated wastewater treatment facility, consisting of upper (solids separators, anaerobic lagoons, and aerobic ponds) and lower (wetland cells) subsystems, has been built to replace the lagoon at a dairy in Arizona, USA. The collection sump of the new waste treatment facility collects all dairy wastewater outflow. Wastewater is then pumped to solids separators, and flows by gravity to anaerobic ponds and aerobic ponds. The upper subsystem is expected to treat the water sufficiently so that the wetland cells may achieve further pollutant reductions. The lower subsystem, comprised of 8 surface wetland cells with an approximate surface area of 5,000 m2, receives outflow from the ponds. The cells are planted with cattail (Typha domingensis), soft-stem bulrush (Scirpus validus), and reed (Phragmites australis). After treatment is completed via the lagoons and ponds followed by the wetland cells, the wastewater can be reused to flush barns or to irrigate crops. Performance of the overall system is evaluated by measuring physical, chemical and biological parameters in water samples taken from selected locations along the treatment system. Chemical parameters studied include biochemical oxygen demand, pH, total suspended solids, nitrogen species. Biological monitoring included coliforms (total and fecal) and Listeria monocytogenes.

Download Full-text

Research Progress of Desertification and Its Prevention in Mongolia

Sustainability ◽

10.3390/su13126861 ◽

2021 ◽

Vol 13 (12) ◽

pp. 6861

Author(s):

Xiya Liang ◽

Pengfei Li ◽

Juanle Wang ◽

Faith Ka Shun Chan ◽

Chuluun Togtokh ◽

...

Keyword(s):

Model Development ◽

Mitigation Strategies ◽

Research Progress ◽

Prevention Measures ◽

Interdisciplinary Approaches ◽

The World ◽

Impacting Factors ◽

Decoupling Analysis ◽

And Control ◽

The Relationship

Mongolia is a globally crucial region that has been suffering from land desertification. However, current understanding on Mongolia’s desertification is limited, constraining the desertification control and sustainable development in Mongolia and even other parts of the world. This paper studied spatiotemporal patterns, driving factors, mitigation strategies, and research methods of desertification in Mongolia through an extensive review of literature. Results showed that: (i) remote sensing monitoring of desertification in Mongolia has been subject to a relatively low spatial resolution and considerable time delay, and thus high-resolution and timely data are needed to perform a more precise and timely study; (ii) the contribution of desertification impacting factors has not been quantitatively assessed, and a decoupling analysis is desirable to quantify the contribution of factors in different regions of Mongolia; (iii) existing desertification prevention measures should be strengthened in the future. In particular, the relationship between grassland changes and husbandry development needs to be considered during the development of desertification prevention measures; (iv) the multi-method study (particularly interdisciplinary approaches) and desertification model development should be enhanced to facilitate an in-depth desertification research in Mongolia. This study provides a useful reference for desertification research and control in Mongolia and other regions of the world.

Download Full-text

The Impact of the Aqueous Phase Chemistry of HNO4 on Gas Phase Tropospheric Chemistry

Journal of Aerosol Science ◽

10.1016/s0021-8502(21)00128-2 ◽

2001 ◽

Vol 32 ◽

pp. 269-270

Author(s):

J.E. WILLIAMS ◽

F.J. DENTENER ◽

A.R. van den BERG

Keyword(s):

Gas Phase ◽

Aqueous Phase ◽

Tropospheric Chemistry ◽

Phase Chemistry ◽

The Impact

Download Full-text

Model development and control of an auto-refrigerated polystyrene polymerization reactor

Transactions of the Institute of Measurement and Control ◽

10.1177/01423312211025125 ◽

2021 ◽

pp. 014233122110251

Author(s):

Reyhane Mokhtarname ◽

Ali Akbar Safavi ◽

Leonhard Urbas ◽

Fabienne Salimi ◽

Mohammad M Zerafat ◽

...

Keyword(s):

Temperature Control ◽

Model Development ◽

Heat Removal ◽

Superior Performance ◽

Polymerization Process ◽

Vacuum System ◽

Control Scheme ◽

Simulation Results ◽

And Control ◽

Operating Plant

Dynamic model development and control of an existing operating industrial continuous bulk free radical styrene polymerization process are carried out to evaluate the performance of auto-refrigerated CSTRs (continuous stirred tank reactors). One of the most difficult tasks in polymerization processes is to control the high viscosity reactor contents and heat removal. In this study, temperature control of an auto-refrigerated CSTR is carried out using an alternative control scheme which makes use of a vacuum system connected to the condenser and has not been addressed in the literature (i.e. to the best of our knowledge). The developed model is then verified using some experimental data of the real operating plant. To show the heat removal potential of this control scheme, a common control strategy used in some previous studies is also simulated. Simulation results show a faster dynamics and superior performance of the first control scheme which is already implemented in our operating plant. Besides, a nonlinear model predictive control (NMPC) is developed for the polymerization process under study to provide a better temperature control while satisfying the input/output and the heat exchanger capacity constraints on the heat removal. Then, a comparison has been also made with the conventional proportional-integral (PI) controller utilizing some common tuning rules. Some robustness and stability analyses of the control schemes investigated are also provided through some simulations. Simulation results clearly show the superiority of the NMPC strategy from all aspects.

Download Full-text

Oxidation of substituted aromatic hydrocarbons in the tropospheric aqueous phase: kinetic mechanism development and modelling

Physical Chemistry Chemical Physics ◽

10.1039/c7cp08576a ◽

2018 ◽

Vol 20 (16) ◽

pp. 10960-10977 ◽

Cited By ~ 17

Author(s):

Erik H. Hoffmann ◽

Andreas Tilgner ◽

Ralf Wolke ◽

Olaf Böge ◽

Arno Walter ◽

...

Keyword(s):

Aqueous Phase ◽

Aromatic Hydrocarbons ◽

Aromatic Compounds ◽

Kinetic Data ◽

Kinetic Mechanism ◽

Detailed Model ◽

Model Studies ◽

Phase Chemistry

An aqueous-phase chemistry mechanism for the oxidation of aromatic compounds in the atmosphere is developed based on available kinetic data. Detailed model studies successfully describe the oxidation and functionalization of monoaromatic compounds in the atmosphere.

Download Full-text

An advanced scheme for wet scavenging and liquid-phase chemistry in a regional online-coupled chemistry transport model

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-1177-2013 ◽

2013 ◽

Vol 13 (3) ◽

pp. 1177-1192 ◽

Cited By ~ 19

Author(s):

C. Knote ◽

D. Brunner

Keyword(s):

Aqueous Phase ◽

Climate Model ◽

Transport Model ◽

Measurement Data ◽

Coupled System ◽

Cloud Microphysics ◽

Microphysics Scheme ◽

Meteorological Model ◽

Wet Scavenging ◽

Phase Chemistry

Abstract. Clouds are reaction chambers for atmospheric trace gases and aerosols, and the associated precipitation is a major sink for atmospheric constituents. The regional chemistry-climate model COSMO-ART has been lacking a description of wet scavenging of gases and aqueous-phase chemistry. In this work we present a coupling of COSMO-ART with a wet scavenging and aqueous-phase chemistry scheme. The coupling is made consistent with the cloud microphysics scheme of the underlying meteorological model COSMO. While the choice of the aqueous-chemistry mechanism is flexible, the effects of a simple sulfur oxidation scheme are shown in the application of the coupled system in this work. We give details explaining the coupling and extensions made, then present results from idealized flow-over-hill experiments in a 2-D model setup and finally results from a full 3-D simulation. Comparison against measurement data shows that the scheme efficiently reduces SO2 trace gas concentrations by 0.3 ppbv (−30%) on average, while leaving O3 and NOx unchanged. PM10 aerosol mass was increased by 10% on average. While total PM2.5 changes only little, chemical composition is improved notably. Overestimations of nitrate aerosols are reduced by typically 0.5–1 μg m−3 (up to −2 μg m−3 in the Po Valley) while sulfate mass is increased by 1–1.5 μg m−3 on average (up to 2.5 μg m−3 in Eastern Europe). The effect of cloud processing of aerosols on its size distribution, i.e. a shift towards larger diameters, is observed. Compared against wet deposition measurements the system tends to underestimate the total wet deposited mass for the simulated case study.

Download Full-text

Study of Ponds in Kathmandu Valley and Analysis of their Present Situation

Historical Journal ◽

10.3126/hj.v12i1.35438 ◽

2020 ◽

Vol 12 (1) ◽

pp. 38-54

Author(s):

Bikash Adhikari ◽

Anmol Parajuli ◽

Prakash Adhikari

Keyword(s):

Dissolved Oxygen ◽

Sustainable Management ◽

Field Survey ◽

Oxygen Demand ◽

Present Situation ◽

Control Fish ◽

Kathmandu Valley ◽

E Coli ◽

Dug Wells ◽

And Control

Ponds in Kathmandu were constructed to feed the sub surface aquifers of stone spouts and dug wells at all seasons. The study focuses on how the ponds have been saved, reduced in size or completely lost. The causes behind the degradation of ponds are forces of intervention and disturbances that lead to the loss of the originality, quality and quantity of ponds throughout its timeline. Out of eight existing ponds in the study area, 10 samples were taken from eight different ponds for quality assessment. The historical significances and status, uses as of 2019 are tabulated based on field survey. The paper focuses on the study of pH, Total Solids, Electrical Conductivity, Ammonia, Nitrate, Phosphate, Ammonia, Dissolved Oxygen, Biological Oxygen Demand, Total Organic Matter, Chlorophyll, E. Coli, and dimensions of existing ponds. The physical, social stresses and lack of regular inspection of ponds have contributed to their degradation. However, the existing ponds require sustainable management. Proper safeguarding mechanism should be developed for the regular aeration of water in the ponds such as fountains so that the ponds have more dissolved oxygen eliminating faulty smell and control fish death.

Download Full-text

Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-2913-2013 ◽

2013 ◽

Vol 13 (1) ◽

pp. 2913-2954 ◽

Cited By ~ 2

Author(s):

P. Renard ◽

F. Siekmann ◽

A. Gandolfo ◽

J. Socorro ◽

G. Salque ◽

...

Keyword(s):

Aqueous Phase ◽

High Resolution Mass Spectrometry ◽

Organic Aerosol ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Methyl Vinyl ◽

Phase Chemistry ◽

Dissolved O2

Abstract. It is now accepted that one of the important pathways of Secondary Organic Aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the liquid phase chemical mechanisms leading to macromolecules are still not well understood. For α-dicarbonyl precursors, such as methylglyoxal and glyoxal, radical reactions through OH-oxidation produce oligomers, irreversibly and faster than accretion reactions. Methyl vinyl ketone (MVK) was chosen in the present study as it is an α, β-unsaturated carbonyl that can undergo such reaction pathways in the aqueous phase and forms even high molecular weight oligomers. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under atmospheric relevant conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series) are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the supremacy of oligomerization reactions after several minutes of reaction. These processes, together with the large ranges of initial concentrations investigated (60–656 μM of dissolved O2 and 0.2–20 mM of MVK) show the fundamental role that O2 likely plays in atmospheric organic aerosol.

Download Full-text