Christopher M. Miller

Hydrogen peroxide decomposition and quinoline degradation in the presence of aquifer material

Hydrogen peroxide is used as a source of oxygen for enhanced bioremediation of contaminated subsurface environments and as an oxidant in engineered systems. While a number of aspects of hydrogen peroxide chemistry are well understood, the importance and relationship between hydrogen peroxide decomposition and contaminant degradation in the presence of subsurface materials is not clear. We report on batch and column studies examining this relationship using quinoline and a sandy aquifer material. The rate of hydrogen peroxide decomposition followed a simple first order relationship, but the loss of quinoline was much more complex than anticipated. The stoichiometric efficiency (i.e. the amount of quinoline degraded for a given loss in hydrogen peroxide) increased dramatically with decreasing concentration of aquifer material. Surface scavenging of reactive intermediates is believed to cause this unexpected behavior. This hypothesis was supported by increased quinoline removal after treatment to remove or inactivate catalytic sites. A model is proposed capable of predicting the extent of quinoline degradation as a function of the aquifer material solids concentration. The findings show that batch and column data for this system and perhaps others involving reactive intermediates must be interpreted with caution. Our results suggest that phosphate addition to retard hydrogen peroxide decomposition could increase contaminant degradation, previously attributed to only biological processes. It may also be possible to enhance chemical degradation in the subsurface and in engineered systems by addition of amendments to modify the surfaces and control reaction pathways.

Chemical and microbiological assessment of pendimethalin-contaminated soil after treatment with Fenton's reagent

This study assessed chemical effects and microbial response after Fentons treatment of pendimethalin contaminated soils. The efficiency of the rapid chemical transformation of pendimethalin varied from 25% to greater than 90%. The highest efficiency was associated with a soil having comparatively low organic matter and low acid neutralizing capacity. This is consistent with the role of organic matter as a free radical scavenger and the optimum formation of free radicals at low pH. Potential heterotrophic activity, as measured by glucose mineralization, decreased with increasing pendimethalin concentration, but this inhibitory effect was removed after Fentons treatment. Treatment also released BOD, COD, TOC, and nitrate into solution. The organic matter released into solution was biodegradable and served as a substrate for subsequent microbial growth. Analysis of the microbial population growing in the Fentons treated soil leachates showed an overall decrease in (culturable) heterotrophic diversity, but an increase in the concentration of Pseudomonas species. These results suggest that Fentons treatment of pendimethalin contaminated soil created favorable conditions for microorganisms desirable for bioremediation.

Assessment of dissolved organic matter fluorescence PARAFAC components before and after coagulation-filtration in a full scale water treatment plant.

Fluorescence monitoring of the raw and treated water after coagulation-filtration in a drinking water treatment plant in Northeast Ohio was conducted during a period of 32 months. Principal fluorophore groups present in the dissolved organic matter (DOM) of the raw, treated, raw-treated combined water and differential fluorescence data sets comprising over 680 samples were determined through Parallel Factor (PARAFAC) analysis. Four components (two humic-like and two with protein nature) were identified in each model and their degree of similarity was evaluated using the Uncorrected Matrix Correlation (UMC), a measure of spectral overlapping. Results show that spectral characteristics of the components in the independent models are comparable (average UMC > 0.98), indicating that from a PARAFAC perspective, components in the raw water are not experiencing major transformations beyond removal through the treatment process and new fluorescent components are not being formed. Coagulation assessment based on PARAFAC application to the differential excitation-emission matrices (ΔEEM), representing the portion of fluorescence removed after treatment, is introduced in this paper along with the volumetric evaluation of the components present in a sample as an alternative approach to determine their relative contribution. Volumetric analysis revealed a predominance of humic components, constituting about 80% in the raw and treated water. Results of the ΔEEM model indicated that the most amenable component to be removed by coagulation (removal ≈ 50%) at full scale operation is a humic-like fluorophore with predominance in the raw water, while removal of the protein-like components was about 30%. Results also show that the PARAFAC sample loadings exhibit a higher association with the total EEM signal in the raw and treated water samples when compared with alternative analysis techniques. These results support the analysis of the PARAFAC components present in the raw and treated samples as a viable measure for assessment of the coagulation process in a drinking water treatment plant.

Oxidation behavior of aqueous contaminants in the presence of hydrogen peroxide and filter media

Abstract Hydrogen peroxide has been used as an oxidant to degrade contaminants in solutions and soils. A poor understanding of the numerous variables that are involved makes it difficult to determine dominant contaminant removal mechanisms. Our primary objective was to examine the relationship between contaminant (quinoline and nitrobenzene) degradation rate and the rate of hydrogen peroxide decomposition on filter media. Both batch and continuous flow column experiments were conducted. In general, the rate of contaminant degradation was proportional to the rate of hydrogen peroxide decomposition, but the mass of contaminant removed depended on the amount of hydrogen peroxide decomposed, filter medium concentration, and filter medium characteristics. For increasing filter medium concentration and equivalent loss of hydrogen peroxide, the mass of contaminant degraded was found to decrease. In addition, acid-hydroxylamine treatment of the selected filter medium, to examine the role of reducible metal oxide coatings, resulted in greater contaminant removals than the parent material despite a slower hydrogen peroxide decomposition rate. The observed hydrogen peroxide decomposition and contaminant oxidation results are consistent with a reaction scheme whose central elements include: (1) a rate limiting filter medium surface catalyzed reaction initiating hydrogen peroxide decomposition with the formation of a reactive intermediate, (2) a competing reaction of the intermediate with the filter medium surface, and (3) reaction of the same intermediate with the aqueous organic contaminant. Loss of quinoline and nitrobenzene is most likely a solution phase reaction because sorption of these compounds was small over the pH range 7–8 and oxidation efficiency did not increase with increasing filter medium concentration, which would be expected if the reactions were occurring on the surface. Finally, enhanced oxidation of quinoline and nitrobenzene on the treated material is explained by more efficient use of the reactive intermediates for contaminant oxidation due to a reduction in the number of scavenging sites associated with reducible metal oxide coatings.

Lithic controls on the removal of iron and remediation of acidic mine drainage

Abstract The remediation of streams adversely affected by acidic mine drainage often employs limestone as a neutralization agent. However, metal precipitation on the limestone surface can render it ineffective. This investigation reports preliminary field and laboratory results demonstrating that, in the presence of a mixture of limestone and sandstone, iron preferentially precipitates on the sandstone surface, and iron removal from aqueous solution is greater than with either of the materials alone. First, a river in Tennessee (USA) with preferential iron precipitation was characterized with respect to water quality and lithic surface morphology. Second, a field experiment where lithic samples were placed in an Ohio stream receiving coal mine drainage demonstrated that iron hydroxide preferentially coats quartz-rich lithologies. Finally, laboratory experiments confirmed enhanced iron removal in the presence of mixed lithic surfaces. Based on these results, the use of multiple lithic surfaces, particularly in-stream, has the potential to provide improved methods for the treatment of acidic mine wastes.

A PARAFAC-Based Long-Term Assessment of DOM in a Multi-Coagulant Drinking Water Treatment Scheme

A parallel factor (PARAFAC) analysis approach was used to study the character and composition of dissolved organic matter (DOM) in a multicoagulant (two aluminum-based coagulants) full scale drinking water treatment plant. A three year, long-term assessment was conducted based on deconstruction of the excitation-emission matrices (EEM) of over 1000 water samples collected before and after parallel coagulation treatment basins. Two humic moieties and a protein-like group were identified in the raw and treated waters. Apportionment of fluorophores was established using a novel approach based on the overall fluorescence intensity (OFI) of PARAFAC components. Uncorrected matrix correlation (UMC) revealed minimal changes of the fluorescence moieties after treatment (UMC > 0.98), and a comparable effect of both coagulants on the structure (UMC > 0.99) and distribution of these groups. Coagulation increased the proportion of the protein-like fluorophore and preferentially removed a humic-like group irrespective of the coagulant. Preference for this moiety was supported by a coagulant-affinity factor derived from the association between PARAFAC components after treatment. The suitability of a PARAFAC-based approach for coagulant evaluation/selection was demonstrated when compared to a dissolved organic carbon (DOC)-based criterion. This paper contributes to the understanding of the behavior of PARAFAC components in water treatment processes and presents several approaches for the future monitoring and control of coagulation at full scale treatment facilities.

Service learning in the library and information science curriculum: The perspectives and experiences of one Multimedia/User Education class

Abstract This article provides a case study of a class project in Multimedia/User Education in the Library and Information Science program at the University of Iowa. The goals of the class were to develop multimedia skills, develop conceptual models for implementing multimedia in libraries, and develop a culture of collaborative teaching and learning within the group of students who were enrolled. The course used service learning pedagogy to achieve these ends. Students developed web sites for public libraries in Iowa that, in many cases, are used in those libraries. In this article, the instructor of the course describes the design of the class, and the students contribute their observations about the service learning experience.

Evaluation of Management Alternatives for Truck Wash Water Generated During Winter Maintenance Activities

The purpose of this research was to identify alternative strategies for managing wash water generated during routine washing of salt trucks at Ohio Department of Transportation (ODOT) maintenance facilities lacking access to sanitary sewer and to assess their costs. Eighteen potential management strategies were identified and evaluated. Six of these strategies were included in a detailed cost analysis, which indicated that site-specific conditions directly affect the cost of alternative management strategies and that tying a facility into the sanitary sewer is not always the most cost-effective strategy. For a county maintenance facility with 12 trucks and 30 winter events, tying into the sanitary sewer was the most cost-effective strategy when the capital cost was less than US

Fenton's Reagent Degradation of 2,4-Dinitrotoluene in Water–Acetone Mixtures

173,640; however, when the capital cost was greater than US

Laboratory techniques for evaluating the effectiveness of salt neutralizers for the corrosion prevention of winter maintenance equipment

285,333, four of the five alternative strategies identified were more cost-effective than tying into the sanitary sewer.