Thesis Details

Thesis Title: Analysis of the Impact of Concentration of Mixed Liquor Suspended Solids, Selected Salts, and Surfactants on Bacteria Respiration Rate in Wastewater
Thesis Author: Jeff Haburay
Abstract: Chemical usage has increased dramatically in the past several decades. Conventional wastewater treatment methods are capable of treating residuals, to a certain degree. The untreated residuals that are discharged from treatment facilities are undesirable and may be potentially hazardous. Textile chemicals of concern may range from salts to dyes to heavy metals. A great deal needs to be learned about their performance in wastewater treatment and in the environment. This thesis establishes the inhibition effects that selected textile salts and surfactants have on biological treatment systems. The thesis evaluated the response of treatment bacteria to increasing levels of sodium chloride, sodium sulfate, and two nonionic surfactants (an alcohol ethoxylate, AE, and an alkylphenol ethoxylate, APE). The treatment bacteria were adjusted in the laboratory to low, average, and high concentrations that are typically found in textile and municipal treatment facilities. The target concentrations were 1000 mg/l, 3000 mg/l, and 5000 mg/l. EC50 (the concentration of chemical that resulted in a 50 percent reduction in bacteria respiration) and the Inhibition Threshold, IT (the concentration of chemical that had no effect on bacteria respiration), were obtained for all of the chemicals at all concentrations of bacteria. The concentration of bacteria had no effect on bacteria respiration when additions of sodium chloride were made. However, when sodium sulfate, alcohol ethoxylate surfactant, and alkylphenol ethoxylate surfactant were added, significant differences in respiration occurred between the different concentrations of bacteria. Data from this research is classified as "preliminary work" and is not intended for regulatory use.