Please read the abstract in the front section of this document / Dissertation (MSc (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Sewage-holding tanks aboard recreational boats store human wastes, thereby preventing the direct discharge of wastewater to the aquatic environment. Water-conserving toilets and limited holding tank volumes produce a highly concentrated waste that must be periodically dumped to a wastewater treatment system. Prior to disposal, many boat operators add commercial preparations to control odors produced in their chemical toilets and holding tanks. The objective of this study was to determine the effects of three holding-tank chemicals on anaerobic wastewater treatment. Specifically, septic-tank performance with respect to effluent total suspended solids (TSS) and chemical oxygen demand (COD) was evaluated. Potential drain-field failure was the concern that led to the selection of TSS and COD. Drain-field failure could result from high solids carry-over or from a high concentration of COD in the effluent which would promote excessive bio-mat growth and clog the system. Laboratory septic tanks were constructed and operated for this evaluation. Methanol, paraformaldehyde and formaldehyde were each listed as an active ingredient in one of three chemical compounds used by recreational boat owners to deodorize sewage-holding tanks. septic-tank effluent TSS concentrations were not adversely effected by the shockloading with wastewater containing these chemicals. Concentrations expected to be achieved by dilution (20 and 50 percent of the recommended additive dose) resulted in septic-tank effluent COD within an acceptable range, which was determined by operation of a control system. Wastewaters containing these concentrations were not detrimental to the septic-tank treatment system. However, the full manufacturers' recommended dose of the odor control chemicals disrupted the system's ability to degrade COD. At full strength, the para formaldehyde and formaldehyde deodorants were particularly detrimental; no recovery occurred after the two-day shock-dose was completed. / Master of Science

M. Tech. Chemical and Metallurgical Engineering / Focuses on developing a reproducible, regenerable, effective and affordable adsorbent for the removal of fluoride, phosphorus and arsenic from water. The adsorption media should perform at room or low temperatures. To perform basic mathematical modelling to aid in adsorber design. The specific objectives are as follows: to apply a simple thermo-chemical process to convert limestone into a robust adsorption media ; to pelletize thermo-chemically converted limestone using organic binders ; to determine the effect of binders on arsenic, fluoride and phosphate removal from water and to apply basic models to interpret breakthrough results.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 131-139). Also available via the Internet.

This research investigated the effect of copper and nickel on the performance of a laboratory scale activated sludge system. The wastewater used for this research was the influent to the activated sludge process at the Hoechst Celanese cellulose acetate manufacturing plant, located at Narrows, Virginia. The influent wastewater to the experimental unit was pretreated with lime and then selected amounts of copper and nickel were added separately or together to evaluate their effects on the performance of the system. The Specific Uptake of Metal (SUM), Dissolved Metal (DM), Total Metal Loading Rate (TMLR), and Specific Total Metal Loading Rate (STMLR) were useful parameters for analysis of the effects of the metals on activated sludge performance. No significant changes in effluent COD, SS, and OUR were observed for the acclimated activated sludge when the selected amounts of metals were added but not when either was added separately. The settling characteristics of the activated sludge deteriorated when a combination of copper and nickel were added. The SUM increased at a faster rate at higher metal loading rates than at lower metal loading rates to the reactor. The increases in dissolved metal concentrations in the mixed liquor were a linear function of the metal loading rates. / Master of Science