Ernst M. Davis

Sorption of organics by Selenastrum capricornutum

Abstract The sorption of eight organic compounds by a representative green alga, Selenastrum capricornutum , was determined by gas-liquid chromatography using a series of linear model experiments. The log 10 bioconcentration factors (BCF), defined as the ratio of the concentration on in the algae to the concentration in the aqueous medium, are as follows: benzene, 3.32; toluene, 3.18; chlorobenzene, 3.69; 1,2-dichlorobenzene, 4.17; naphthalene, 4.10; phenanthrene, 4.38; di- n -butylphthalate, 4.36 and pyrene, 4.56. The relation of log 10 BCF correlation with log 10 octanol-water partition coefficient was determined as log 10 BCF = 0.46 log 10 P + 2.36.

Characterization of organic compounds in simulated rainfall runoffs from model coal piles

Model coal piles were constructed and leached with distilled water under simulated rainfall conditions. The piles were composed of one of four coals: two of high sulfur content (Illinois #6 and Western Kentucky), one of low sulfur content (Montana Nerco), and one of variable sulfur content (Texas lignite). There were nine rainfall simulations spaced 15 days apart. The runoffs were collected, extracted at acid and base pH, and analyzed by capillary column gas chromatography/mass spectrometry (GC/MS). Also, an extreme case was simulated by stir-extracting a coal with three different organic solvents in an acid and base medium, and the extracts were analyzed by GC/MS. The most common organic compound identified in any extract was phenanthrene. Aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), and methyl and ethyl substituted PAHs were also identified. The concentration of most of the compounds did not exceed 50 μg/L. The concentrations of compounds in the extreme case simulations ranged from below detection (< 1 μ/L) up to 107 μ/L. The data demonstrated that runoffs from coal piles may contain numerous organic compounds including many PAHs.

Regrowth potential of coliforms after UV disinfection of municipal wastewater

Photoreactivation of fecal coliforms and subsequent regrowth was investigated in effluents of wastewater treatment plants using ultraviolet light as the disinfectant. Shielding of bacteria ingested in Daphnia sp in the plant outfalls was shown to be a major contributor to increased fecal coliform, E. coli, fecal streptococci and enterococci after fragmentation of the Daphnia sp due to normal dieoff. Representative fecal coliform colonies that comprised the regrowth population were identified to species with E. coli, a small fraction of the total fecal coliform population.

Probable causes for reduced BOD test results in hypersaline wastewaters

Abstract The causes for erratic BOD results from wastewaters containing elevated concentrations of salt were investigated. Standard organic solutions and an industrial waste were tested with sewage seed and known species of salt tolerant bacteria using standard and hypersaline dilution water at three salt concentrations. Significant BOD differences were found when saline wastes were diluted with standard (non-saline) BOD dilution water. Bacterial populations to genera were monitored and it was shown that equivalent numbers of bacteria did not have the same capability to degrade a given amount of waste with increases in salt concentrations to the 3% level. Seeding of hypersaline wastewaters with known salt tolerant species is recommended for consistent BOD results.