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Thesis (M. Phil.) - University of Queensland, 2005. / Includes bibliography.

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2007. / Title from title page screen (viewed on Sept. 18, 2008). Thesis advisor: C. Neal Stewart, Jr. Vita. Includes bibliographical references.

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona, 1986. / Includes bibliographical references (leaves 207-213).

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona, 1988. / Includes bibliographical references.

Thesis (M.A. in sociology)--Washington State University, August 2008. / Includes bibliographical references (p. 42-44).

Thesis (M.A.)--Duquesne University, 2004. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 90-99) and index.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 469-477). Available also in a digital version from Dissertation Abstracts.

The discharge of a landfill leachate to a receiving water body can cause a serious pollution problem. One component of leachate that can have a severe impact on a receiving water body is ammonia and its oxidized form, nitrate. This study investigated the biological treatibility of a high ammonia leachate, with specific regard to nitriification and denitrification. A continuous-feed, single sludge denitrification system with recycle was used. Leachate ammonia concentrations of up to 288 mg/L-N were reduced to less than 1 mg/L. The ammonia was removed by nitrification and bacterial uptake. About 25% of the incoming ammonia was taken up by the bacteria in the anoxic reactor; the rest was subsequently nitrified in the aerobic reactor. The nitrates produced in the aerobic reactor were recycled back to the anoxic reactor to undergo denitrification. Glucose was added directly to the anoxic reactor to aid denitrification. The degree of denitrification was dependent on the glucose loading to the anoxic reactor; however, 100% denitrification was achieved on several occasions. The influent leachate COD removal was 20%; however after the addition of glucose to the system, a mean COD removal of 74% was obtained. Of the COD removed across the system, 85% was used in the anoxic reactor for denitrification, and the remaining 15% was used by the heterotrophs in the aerobic reactor. The four metals monitored regularly, zinc, manganese, nickel and iron were removed by the biomass, but not to the same extent During the latter part of the study, the system was first spiked with manganese, and then - zinc, to try and induce an inhibitory effect on the nitrification process. The manganese had no detectable effect on the system. However, total zinc (>95% soluble) levels of between 14.9 and 17.6 mg/L caused substantial inhibition of the nitrification process, resulting in approximately 70 mg/L ammonia in the effluent (feed = 216 mg/L). This inhibition was also evident from the lower percent nitrification values and the unit nitrification rates. This high influent zinc concentration also caused deflocculation, resulting in the loss of significant quantities of biomass with the effluent. The high zinc concentrations also inhibited the denitrifiers, resulting in a decrease in the ammonia uptake, as well as an increase in the COD (used)/Nitrate+Nitrite (NOT) (reduced) ratios in the anoxic reactor. The zinc levels were then lowered to allow the system to return to normal; after this state had been reached, the influent total zinc (>95% soluble) levels were again increased up to 19.5 mg/L. This concentration of zinc did not result in any ammonia appearing in the effluent; thus, it is possible that the bacteria had acclimatized to these high influent zinc concentrations. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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