scholarly journals Using a Gas-Phase Tracer Test to Characterize the Impact of Landfill Gas Generation on Advective-Dispersive Transport of VOCs in the Vadose Zone

2014 ◽  
Vol 225 (12) ◽  
Author(s):  
Gregg R. Monger ◽  
Candice Morrison Duncan ◽  
Mark L. Brusseau
Keyword(s):  
Gas Phase ◽  
Vadose Zone ◽  
Landfill Gas ◽  
Tracer Test ◽  
Dispersive Transport ◽  
Gas Generation ◽  
The Impact

scholarly journals Review of Research Methods for Assessing the Activity of a Municipal Landfill Based on the Landfill Gas Analysis

2021 ◽  
Vol 65 (2) ◽  
pp. 167-176
Author(s):  
Dorota Porowska
Keyword(s):  
Gas Phase ◽  
Research Methods ◽  
Landfill Gas ◽  
Water Environment ◽  
Gas Analysis ◽  
Economic Management ◽  
Gas Generation ◽  
Municipal Landfill ◽  
The Impact

Accurate projection of gas generation from landfills poses numerous difficulties. One needs to select and use an appropriate method from among several available options, and consider local and individual conditions of a landfill. These aspects are crucial for the economic management of the landfill gas in new landfills, and for assessing the impact of the gas on soil-water environment in old landfills. This paper is aimed at reviewing the research methods that can be used to assess the activity of new municipal waste landfills currently in operation, and of old, closed landfills after reclamation. Landfill activity can be assessed using different models and analysis of the produced gas. The actual data on the investigated municipal landfill showed that the landfill activity can be accurately assessed based on the quantitative determination of biogas formation using the LandGEM method, and the analysis of gas phase variability in the landfill accounting for oxygen, methane, carbon dioxide and hydrogen sulfide share/presence. Each landfill is different and calls for an individual approach or methodological modifications.

Gas-phase Diffusive Tracer Test for the In-Situ Measurement of Tortuosity in the Vadose Zone

2007 ◽  
Vol 184 (1-4) ◽  
pp. 355-362 ◽  
Author(s):  
Geoffrey R. Tick ◽  
Colleen M. McColl ◽  
Irfan Yolcubal ◽  
Mark L. Brusseau
Keyword(s):  
Gas Phase ◽  
Vadose Zone ◽  
Tracer Test ◽  
In Situ Measurement

Chemical Transport Facilitated by Multiphase Flow Systems1

1985 ◽  
Vol 17 (9) ◽  
pp. 1-12 ◽  
Author(s):  
Carl G. Enfield
Keyword(s):  
Organic Carbon ◽  
Boundary Conditions ◽  
Transport Equation ◽  
Fluid Phase ◽  
Chemical Transport ◽  
Facilitated Transport ◽  
Organic Fraction ◽  
Dispersive Transport ◽  
Transformation Of Variables ◽  
The Impact

Relatively immobile chemicals have been observed moving significantly faster than anticipated from hydrophobic theory. A theory is developed considering transport in three mobile fluid phases which can be used to describe this facilitated transport. The convective dispersive transport equation is solved utilizing a transformation of variables which permits utilizing existing solutions covering a wide variety of boundary conditions. The impact of the facilitated transport is demonstrated for one case where the soils organic carbon is 10%. If 2% of the fluid phase is an organic fraction, the theory developed projects that hydrophobic theory may underestimate mobility by more than 100 times. At concentrations of dissolved organic carbon normally observed in nature (5 - 10 mg/l), a measurable increased mobility is anticipated for the very immobile compounds like dioxins.

Landfill Gas Generation Projects Implementation

2020 ◽  
Author(s):  
Andrei A. Achitaev ◽  
Stanislav A. Eroshenko ◽  
Anastasia G. Rusina ◽  
Alexey A. Zhidkov ◽  
Pavel N. Evseenkov
Keyword(s):  
Landfill Gas ◽  
Gas Generation

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

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

scholarly journals Application of random forest regression to the calculation of gas-phase chemistry within the GEOS-Chem chemistry model v10

2019 ◽  
Vol 12 (3) ◽  
pp. 1209-1225 ◽  
Author(s):  
Christoph A. Keller ◽  
Mat J. Evans
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Random Forest Regression ◽  
Data Set ◽  
Gas Phase Chemistry ◽  
Chemical Conditions ◽  
Phase Chemistry ◽  
The Impact

Abstract. Atmospheric chemistry models are a central tool to study the impact of chemical constituents on the environment, vegetation and human health. These models are numerically intense, and previous attempts to reduce the numerical cost of chemistry solvers have not delivered transformative change. We show here the potential of a machine learning (in this case random forest regression) replacement for the gas-phase chemistry in atmospheric chemistry transport models. Our training data consist of 1 month (July 2013) of output of chemical conditions together with the model physical state, produced from the GEOS-Chem chemistry model v10. From this data set we train random forest regression models to predict the concentration of each transported species after the integrator, based on the physical and chemical conditions before the integrator. The choice of prediction type has a strong impact on the skill of the regression model. We find best results from predicting the change in concentration for long-lived species and the absolute concentration for short-lived species. We also find improvements from a simple implementation of chemical families (NOx = NO + NO2). We then implement the trained random forest predictors back into GEOS-Chem to replace the numerical integrator. The machine-learning-driven GEOS-Chem model compares well to the standard simulation. For ozone (O3), errors from using the random forests (compared to the reference simulation) grow slowly and after 5 days the normalized mean bias (NMB), root mean square error (RMSE) and R2 are 4.2 %, 35 % and 0.9, respectively; after 30 days the errors increase to 13 %, 67 % and 0.75, respectively. The biases become largest in remote areas such as the tropical Pacific where errors in the chemistry can accumulate with little balancing influence from emissions or deposition. Over polluted regions the model error is less than 10 % and has significant fidelity in following the time series of the full model. Modelled NOx shows similar features, with the most significant errors occurring in remote locations far from recent emissions. For other species such as inorganic bromine species and short-lived nitrogen species, errors become large, with NMB, RMSE and R2 reaching >2100 % >400 % and <0.1, respectively. This proof-of-concept implementation takes 1.8 times more time than the direct integration of the differential equations, but optimization and software engineering should allow substantial increases in speed. We discuss potential improvements in the implementation, some of its advantages from both a software and hardware perspective, its limitations, and its applicability to operational air quality activities.

scholarly journals Municipal Solid Waste Characterization and Landfill Gas Generation in Kakia Landfill, Makkah

2021 ◽  
Vol 13 (3) ◽  
pp. 1462
Author(s):  
Faisal A. Osra ◽  
Huseyin Kurtulus Ozcan ◽  
Jaber S. Alzahrani ◽  
Mohammad S. Alsoufi
Keyword(s):  
Solid Waste ◽  
Energy Recovery ◽  
Solid Waste Management ◽  
Landfill Gas ◽  
Drainage System ◽  
Solid Wastes ◽  
Generation Model ◽  
Gas Generation ◽  
Municipal Solid Wastes ◽  
Makkah City

In many countries, open dumping is considered the simplest, cheapest, and most cost-effective way of managing solid wastes. Thus, in underdeveloped economies, Municipal Solid Wastes (MSW) are openly dumped. Improper waste disposal causes air, water, and soil pollution, impairing soil permeability and blockage of the drainage system. Solid Waste Management (SWM) can be enhanced by operating a well-engineered site with the capacity to reduce, reuse, and recover MSW. Makkah city is one of the holiest cities in the world. It harbors a dozen of holy places. Millions of people across the globe visit the place every year to perform Hajj, Umrah, and tourism. In the present study, MSW characterization and energy recovery from MSW of Makkah was determined. The average composition of solid waste in Makkah city is organic matter (48%), plastics (25%), paper and cardboard (20%), metals (4%), glass (2%), textiles (1%), and wood (1%). In order to evaluate energy recovery potential from solid waste in Kakia open dumpsite landfill, the Gas Generation Model (LandGEM) was used. According to LandGEM results, landfill gas (methane and carbon dioxide) generation potential and capacity were determined. Kakia open dump has a methane potential of 83.52 m3 per ton of waste.

scholarly journals Gaseous chemistry and aerosol mechanism developments for version 3.5.1 of the online regional model, WRF-Chem

2014 ◽  
Vol 7 (6) ◽  
pp. 2557-2579 ◽  
Author(s):  
S. Archer-Nicholls ◽  
D. Lowe ◽  
S. Utembe ◽  
J. Allan ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Chemical Mechanism ◽  
Reduced Form ◽  
Sea Spray ◽  
Wind Fields ◽  
Aerosol Composition ◽  
Aerosol Emission ◽  
Sea Spray Aerosol ◽  
The Impact ◽  
Phase Chemical

Abstract. We have made a number of developments to the Weather, Research and Forecasting model coupled with Chemistry (WRF-Chem), with the aim of improving model prediction of trace atmospheric gas-phase chemical and aerosol composition, and of interactions between air quality and weather. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been added, using the Kinetic Pre-Processor (KPP) interface, to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas-phase schemes. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. We have worked on the European domain, with a particular focus on making the model suitable for the study of nighttime chemistry and oxidation by the nitrate radical in the UK atmosphere. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments are illustrated, using a modified version of WRF-Chem 3.4.1, in order to demonstrate the impact that these changes have in the Northwest European domain. These developments are publicly available in WRF-Chem from version 3.5.1 onwards.

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