Nicholas J. Fendinger

Measurement of alkyl ethoxylate surfactants in natural waters

Alkyl ethoxylate alcohols (AE) are used in a wide variety of household cleaning products. In order to monitor environmental levels of AE and to determine AE removal during wastewater treatment, an analytical procedure that provides total AE concentration resolved by alkyl chain length for various environmental matrices (influent, effluent, and river water) was developed. The method utilizes a reverse-phase column to extract and concentrate AE from surface waters and wastewaters and utilizes strong anionic and cationic exchange columns to remove potential interferences. AE were reacted with hydrogen bromide to form corresponding alkyl bromide derivatives that were analyzed by capillary gas chromatography with mass selective detection. Recovery of AE from influent, treatment plant effluent, and river water was quantitative (65-102%) over a range of concentrations for all matrices. AE removal was 99% at two activated sludge treatment plants and 92% at two trickling filter plants. Total AE in low dilution (effluent to river water) surface waters downstream from wastewater treatment plants were less than 0.037 mg/L.

The effect of environmental storage conditions on the organic content of simulated coal leachates

Simulated coal leaching experiments were conducted at 25°C and 7°C, after lime treatment, and under reduced oxygen tension. Leachate from coal stored at lower temperatures, reduced oxygen and had higher pH values with lime, lower conductivities, and lower concentrations of dissolved organic carbon (DOC) and total organic carbon (TOC) than leachates from coal stored at higher temperatures and/or oxygen rich conditions. The leaching of DOC is related to acid production by chemoautotrophic bacteria. Lower concentrations of DOC in leachates from coal treated with lime can be attributed to neutralization, subsequent decreased production of acidity by autotrophic bacteria, and utilization of DOC by heterotrophic bacteria. Concentrations of aliphatic and aromatic hydrocarbons associated with the liquid fraction of leachates were not influenced by temperature or reduced oxygen concentration. Changes in the aliphatic hydrocarbon content of the coal leachates are related to metabolism by heterotrophic bacteria and/or to decreased acidity.

Influence of coal source and treatment upon indigenous microbial communities

SummaryThe leaching of six Eastern coals was investigated using experimental coal columns subjected to simulated leaching events. Measurements of CO2 assimilation and specific enrichment cultures indicated that the microbial communities of all leachates were dominated by iron- and sulfur-oxidizing chemoautotrophic bacteria. Comparison of CO2 assimilation rates in leachates and core samples of leached coal indicated that most chemoautotrophs remained within coal columns during leaching. Mean numbers of chemoautotrophic bacteria in leachate samples were correlated with concentrations of dissolved iron and sulfate. Leachates from unwashed, run-of-mine coals contained more chemoautotrophs and more iron and sulfate than did leachates from washed, final product coals. After several leachings, the ratio of sulfur oxidizers to iron oxidizers tended to increase. These data suggest that the chemoautotrophic community of final product coals may be pyritelimited. Aerobic heterotrophs constituted a minor component of the microbial community in leachates from the six coals and their abundance and metabolic activity were apparently not influenced by the beneficiation history of the coal. Changes in rates of acetate metabolism may have been related to microbial succession within the heterotrophic community of coal columns. In all leachates, rates of tritiated methylthymidine assimilation were correlated with rates of acetate incorporation but not with CO2 assimilation, even though autotrophs dominated the microflora. Thus, thymidine assimilation rates appear to reflect activities or growth of mainly heterotrophic microorganisms in leachate.