This study involves the development of a biofilm reactor that supports growth of a deep biofilm on a gas permeable membrane. The reactor solution is not aerated, and oxygen is supplied through the membrane. The reactor is termed a substratum-aerated-biofilm reactor or SAB. With adequate concentrations of electron-donors and electron-acceptors, a deep biofilm grows on the membrane and is comprised of different layers of bacterial activity. The aerobic layers are near the membrane support, while the anaerobic layers are near the biofilm-liquid boundary. In the SAB, the substrate diffuses from the bulk liquid into the biofilm to react. Oxygen diffuses through the membrane into the biofilm. All products likewise are transported by molecular diffusion through the biofilm and into the bulk liquid. The reactors consisted of a reactor wall made of a plexiglass cylinder with the gas permeable membrane supported on a shallow rotating cup. The cup was designed so that the cup and the membrane function as a flat plate. The flat plate was utilized for support of the biological growth, transfer of oxygen, and mixing of the bulk liquid and the gas phase. The experiments were conducted in completely mixed, continuous-flow reactors maintained at 25°C with a hydraulic detention of 8 hours. Pure oxygen was delivered to a gas compartment under the membrane. All reactors were fed a synthetic waste buffered to pH 7.0. The background solution for the feed solution was made from distilled water combined with adequate inorganic nutrients and vitamins. The background solution was supplemented with acetate and ammonia to obtain the desired substrate compositions. Combined nitrification and heterotrophic oxidation activity resulted when the SABs where fed 5 or 10 mg/1 acetate, and 10 mg-N/1 ammonia. Combined nitrification, heterotrophic oxidation, and denitrification resulted with acetate concentration of 20, 40, and 100 mg/1, and 10 mg- N/1 ammonia. Combined heterotrophic oxidation and fermentation resulted with acetate concentration of 800 mg/1, and 10 mg-N/1 ammonia. A series of mass balances were developed to determine the fate of the nitrogen compounds and acetate. These results showed that the flux values for carbon oxidation, nitrification, denitrification, and fermentation are higher than those reported for competing technologies such as rotating biological contactors. / Graduation date: 1990

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published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy

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The effectiveness of a cheap, low-tech, environmentally and technically favorable treatment of secondary treated municipal wastewater by contaminant removal through a floodplain-soil filter was evaluated using floodplain-simulating field lysimeters, packed with a sandy soil in 2002 and sand in 2003 and 2004. Secondary treated wastewaters from Vaudreuil (2002 and 2003) and Pincourt (2004) Wastewater Treatment Plants were used as influent. This was applied at rates of 0.06, 0.19, and 0.31 m3 m-2 d -1 to vegetated lysimeters, and at a rate of 0.19 m3 m-2 d-1 to bare-soil lysimeters. / Removal of NH4+-N, NO3--N, and COD from the influent was studied in all three years. Irrespective of flow rate or year, the system removed 62~84%, 96~99%, and 6~67% of TKN, NH4+-N, and COD, respectively, from the influent. Under 0.19 m3 m-2 d-1 flow rate, vegetated systems removed slightly more of these constituents from the influent, than did bare-soil lysimeters. Organic degradation mainly occurred in the top 0.1 m soil depth. Degradation of organic and inorganic influent nitrogen increased NO3--N levels in the effluent. Only minimal increases in soil-N levels and N2O emissions occurred with increasing application rates. The nitrogen mass balance accounted for 85∼98% (2003) and 67∼96% (2004) of input nitrogen (through leaching, soil retention, and N2O emissions), the remaining portion being attributable to vegetative effects and volatilization of non-N2O nitrogenous gases. The under established vegetation on the lysimeters reduced nitrogen leaching through soil, being 6% (2003) and 60% (2004) more effective than bare soil. / Effluent water quality improved with decreasing levels of heavy metals. Compared to influent levels, in vegetated lysimeters, under all flow rates, mean effluent As, Cd, Cu, Ni, Pb, and Zn levels had dropped by 58%, 9%, 3%, 37%, 63%, and 52% in 2003, and by 20%, 63%, 5%, 23%, 18%, 57%, and 79% for As, Cd, Cr, Cu, Ni, Pb, and Zn, in 2004. In both years, similar decreases in heavy metal levels occurred in the bare soil lysimeters. Across all flow rates and influent concentrations, soil heavy metal levels increased. In 2004, even low heavy metal content influent further increased (6∼179%) their accumulation in soil. As inputs of heavy metals to the soil increased with the increase in application rates, their associated times to reach maximum permissible limits also decreased. / LEACHN simulation of NO3--N in leachate arising from wastewater application, showed lowered levels with increasing flow rates, due to enhanced denitrification in the resulting anoxic upper soil zones. The simulation under continuous wastewater application at different range of nitrogen concentrations (low, medium, high) showed an increase of NO 3--N levels in the leachate with increasing N-levels. For all flow rates, and under tropical or humid conditions, the effluent NO 3--N levels remained below permissible limits for the low-N content wastewater applications. Intermittent applications, under all wastewater N-contents and flow rates, reduced NO3--N levels in the leachate by 51∼89% compared to continuous wastewater application, and permissible limits were not exceeded. Hence, wastewater with high levels of nitrogenous compounds, as occurs in most developing countries, could be treated by land under an intermittent application pattern, allowing a considerable reduction in nitrate pollution.