Biomedical subjects

James R Mihelcic

Publications and source records attributed to James R Mihelcic.

7 recordsLinked to original sources

PubMed2005

Low-temperature inhibition of the activated sludge process by an industrial discharge containing the azo dye acid black 1.

A municipal wastewater treatment plant (WWTP) receiving industrial dyeing discharge containing acid black 1 (AB1) failed to meet NH(3) and BOD(5) discharge limits, especially for NH(3) during the winter. Dyeing discharge was combined with domestic sewage in volumetric ratios reflecting the range received by the WWTP and fed to sequencing batch reactors at 22 and 7 degrees C. Analysis of the various nitrogen species revealed complete nitrification failure at 7 degrees C with more rapid nitrification failure as the dye concentration increased. Slight nitrification inhibition occurred at 22 degrees C: NH(3) removal decreased from 99.9% for the control compared to only 97.0% removal with dye addition. Dye-bearing wastewater also reduced COD removal by half at 7 degrees C and by one-fifth at 22 degrees C, and increased effluent TSS nearly three-fold at 7 degrees C. Activated sludge quality at 7 degrees C deteriorated after exposure to AB1, as indicated by excessive foaming and the presence of filamentous bacteria and by a decrease in endogenous and exogenous oxygen uptake. Decreasing AB1 loading resulted in partial activated sludge recovery. Eliminating the dye-bearing discharge to the full-scale WWTP led to improved performance bringing the WWTP into compliance with discharge limits.

Amido Black↗

PubMed2004

Design and performance characterization strategy using modeling for biofiltration control of odorous hydrogen sulfide.

Biofilter, dynamic modeling software characterizing contaminant removal via biofiltration, was used in the preliminary design of a biofilter to treat odorous hydrogen sulfide (H2S). Steady-state model simulations were run to generate performance plots for various influent concentrations, loadings, residence times, media sizes, and temperatures. Although elimination capacity and removal efficiency frequently are used to characterize biofilter performance, effluent concentration can be used to characterize performance when treating to a target effluent concentration. Model simulations illustrate that, at a given temperature, a biofilter cannot reduce H2S emissions below a minimum value, no matter how large the biofilter or how long the residence time. However, a higher biofilter temperature results in lower effluent H2S concentrations. Because dynamic model simulations show that shock loading can significantly increase the effluent concentration above values predicted by the steady-state model simulations, it is recommended that, to consistently meet treatment objectives, dynamic feed conditions should be considered. This study illustrates that modeling can serve as a valuable tool in the design and performance optimization of biofilters.

Air Pollutants↗

PubMed2003

Sustainability science and engineering: the emergence of a new metadiscipline.

A case is made for growth of a new metadiscipline of sustainability science and engineering. This new field integrates industrial, social, and environmental processes in a global context. The skills required for this higher level discipline represent a metadisciplinary endeavor, combining information and insights across multiple disciplines and perspectives with the common goal of achieving a desired balance among economic, environmental, and societal objectives. Skills and capabilities that are required to support the new metadiscipline are summarized. Examples of integrative projects are discussed in the areas of sustainability metrics and integration of industrial, societal, and environmental impacts. It is clear that a focus on green engineering that employs pollution prevention and industrial ecology alone are not sufficient to achieve sustainability, because even systems with efficient material and energy use can overwhelm the carrying capacity of a region or lead to other socially unacceptable outcomes. To meet the educational and human resource needs required for this new discipline, the technological and environmental awareness of society must be elevated and a sufficient and diverse pool of human talent must be attracted to this discipline.

Conservation of Natural Resources↗

PubMed2003

Development and evaluation of an environmental multimedia fate model CHEMGL for the Great Lakes region.

This paper describes the development of a multimedia compartmental model--CHEMGL--which predicts the fate and transport of chemicals in the Great Lakes region and can be used for risk assessment. CHEMGL includes 10 compartments that describe a given region: air boundary layer, free troposphere, lower stratosphere, surface water, sediment, surface soil, vadose soil, groundwater zone, plant foliage and plant root. The model assumes that the compartments are completely mixed and chemical equilibrium between the phases within each compartment is assumed (e.g., suspended solids and biota in water). The attenuation mechanisms include advection, transformation reactions, and diffusive and nondiffusive intermedia transport between compartments. Input parameters include a description of each environmental media, emission rates, and chemical-specific properties and reaction rates. The numerical model results are in good agreement with the analytical solution for an example that examines the fate of benzene. Accordingly, the mathematical and computational components of the model were verified. CHEMGL predicted the concentration of four representative chemicals (atrazine, benzo[a]pyrene, benzene and hexachlorobenzene) in all five basins: Superior, Michigan, Huron, Erie and Ontario. The predicted concentrations fell within one to two orders of magnitude of data reported in the literature. These results suggest that the model is appropriate for estimating the fate and exposure of chemicals for a screening level risk assessment.

Fresh Water↗

PubMedDate not supplied

Optimization of biofiltration for odor control: model development and parameter sensitivity.

A dynamic model that describes the mass transport and attenuation of odor-causing air emissions (i.e., hydrogen sulfide and other reduced sulfur compounds) in a biofiltration unit was developed and incorporated into a software package called Biofilter. Mechanisms included advective flow, mass transfer from the bulk phase to the biofilm, biofilm internal diffusion, and biological reaction in the biofilm. A dimensionless analysis revealed that the mass transport and attenuation of target compounds can be characterized by several dimensionless groups. Model equations were converted to ordinary differential equations using orthogonal collocation and the resulting ordinary differential equations were solved using the DGEAR algorithm. Numerical solutions were verified by comparing model simulations to analytical solutions. The model simulations showed that the existence of a water layer surrounding the biofilm in a biofiltration unit lowers the removal efficiency of hydrogen sulfide. A sensitivity analysis of model parameters (including the film transfer coefficient, biofilm diffusivity, biofilm thickness, maximum specific biomass growth rate, yield coefficient, half-saturation coefficient, and initial active biomass concentration) using data from two biofilters located at the Cedar Rapids (Iowa) Water Pollution Control Facilities, showed that biofilm internal diffusion and biofilm kinetics have a significant effect on hydrogen sulfide removal, while external mass transfer has little effect.

Air Pollutants↗

PubMedDate not supplied

Optimization of biofiltration for odor control: model calibration, validation, and applications.

A dynamic model that describes the biofiltration process for hydrogen sulfide removal from wastewater treatment plant air emissions was calibrated and validated using pilot- and full-scale biofilter data obtained from the Cedar Rapids (Iowa) Water Pollution Control Facilities. After calibration, the model was found to predict the dynamic effluent concentrations of the pilot- and full-scale biofilters well, with the measured data falling within 58 to 80% of the model output values. In addition, the model predicted the trend of the field data, even under field conditions of changing input concentration and at effluent concentrations below 1 ppm by volume. The model demonstrated that increasing gas residence time and temperature and decreasing influent concentration decreases effluent concentration. In addition, model simulations showed that a longer residence time is required to treat dynamic loading increases, indicating that biofilter design should account for the maximum influent concentration. These results can be used to help design and operate biofilters for controlling odorous and hazardous air emissions.

Air Pollutants↗

PubMedDate not supplied

Biogeochemical analysis of hydrogen sulfide removal by a lava-rock packed biofilter.

Although lava-rock-based biofilters have demonstrated their efficiencies for hydrogen sulfide (H2S) removal found in odorous air emissions, the biogeochemical basis for this removal is unclear. In this study, samples of lava rock and rinse water from biofilters at Cedar Rapids Water Pollution Control Facilities (Iowa) were used to study the structure and chemical composition of lava rock and to identify the predominant microorganism(s) present in lava-rock-based biofilters. It was found that iron, in the form of Fe2+ and Fe3+, was present in lava rock. Although literature suggests that Acidithiobacillus thiooxidans are primarily responsible for gaseous H2S removal in biofilters, our study showed that Acidithiobacillus ferrooxidans was the dominant microorganism in the lava-rock-based biofilters. A novel mechanism for H2S removal in a lava-rock-based biofilter is proposed based on the biogeochemical analysis of lava rock.

Acidithiobacillus↗