Walter J. Maier

Characterization of soluble and colloidal phase metal complexes in river water by ultrafiltration. A mass-balance approach.

Ultrafiltration, anodic stripping voltammetry, and atomic absorption spectrophotometry have been used to determine the distribution and degree of association of major trace metals with discrete size fractions of dissolved organic matter which passes initially through a 0.4-pm membrane filter. A novel mass-balance approach has been developed for fractionation of operationally defined, dissolved organic matter and organometallic complexes into well-defined molecularsize ranges. The highest concentrations of trace metals were found in intermediate molecular weight fractions ( 10^3-10^4) with no detectable free or labile metal as determined by anodic stripping voltammetry.

Lake superior organic carbon budget

Abstract The organic carbon concentration of Lake Superior is discussed in terms of a simple mathematical model that treats the lake as a well mixed basin. Major sources, outflows, and biochemically mediated removal of organic carbon are analyzed in the time frame of yearly average values. Data on organic carbon concentrations of watershed drainage, rainfall, anthropogenic inflows and contributions from photosynthetic production are analyzed as are the removal of organics by biochemical oxidation and sedimentation. The long range projected effects of the major sources and sinks on the yearly average organic carbon concentration of the lake are described.

Modeling the influence of nonionic surfactants on biodegradation of phenanthrene

Surfactant mediated solubilization and simultaneous microbial degradation of phenanthrene in a completely mixed batch system has been studied. A mathematical model is presented based on the rates of solids dissolution, substrate biodegradation and oxygen uptake in terms of five coupled differential equations. The model accounts for the concurrent utilization of surfactants for cell growth. The system of differential equations has been solved by numerical integration to calculate the oxygen utilization, cell mass production and substrate concentration as a function of time. Sensitivity analysis of the model indicates that the maximum specific growth rate, the oxygen consumption coefficient, cell yield coefficient and dissolution coefficient are the most significant parameters that control the process. Four commercial nonionic surfactants at a concentration of 25 mg/L were tested to evaluate their effect on biodegradation rates of phenanthrene. The model could adequately predict the oxygen uptake, cell growth and substrate disappearance data observed in the experimental studies. The presence of surfactants enhanced the biodegradation rate for phenanthrene. The results also indicated that the most significant effect of surfactant addition was the increase in the dissolution rate of phenanthrene to the aqueous phase.

Phenanthrene mineralization in soil in the presence of nonionic surfactants

This research addresses the effect of surfactant addition on the microbial degradation of slightly soluble organic compounds in soil. Biodegradation of phenanthrene, coated on sand with a low f oc, was studied in the presence of nonionic surfactants. Phenanthrene coated sand was designed to simulate soil contaminated with excess phenanthrene which remains after evaporation of the lighter hydrocarbon solvents. A mixed culture acclimated to phenanthrene was used as the inoculum. Four nonionic surfactants were used in this study: Triton X‐114, Brij 35, Tween 40 and Corexit 0600. Continuous flow columns were employed to simulate groundwater flow through aquifers. The addition of Corexit 0600 and Tween 40 surfactants enhanced the biodegradation rate of phenanthrene while there was no enhancement by the other two surfactants. No appreciable lag period for mineralization was observed in these experiments. Additional tests are required to assess surfactant bacteria interactions to determine why certain surfactant...

Multicomponent UV Spectral Analysis of Aquatic Organics

ABSTRACT The utilization of multiwavelength ultraviolet absorbtion measurements for analyzing multicomponent mixtures of aquatic organic material is described. Applications are visualized in monitoring organic pollutant levels in natural bodies of water, process control in wastewater treatment and water treatment. The methodology for analyzing measurements of UV absorbance spectra and elemental composition of multicomponent mixtures to determine the concentration in terms of their major constituents is described.