The ability of a self-contained denitrification system, using fermentation products from waste fish solids, to maintain reliable performance was studied. Denitrification performance was described kinetically and stoichiometrically under different initial nitrate-nitrogen and soluble organic carbon to nitrate-nitrogen ratios. Characterization of soluble organic carbon (measured as soluble chemical oxygen demand, sCOD) indicated that volatile fatty acids (VFA) were generated during the fermentation of the waste fish solids. The results from batch experiments showed that over the range of initial nitrate concentrations studied, complete denitrification was achieved within 6 hrs. sCOD, nitrite, and nitrate profiles across several batch experiments showed that transient nitrite accumulations occurred, but the maximum measured concentrations never completely inhibited nitrate removal. The results suggested that the rate of denitrification was influenced by the initial sCOD to nitrate-nitrogen ratio when transient nitrite concentrations remained below 20 mg/L. However, when nitrite-nitrogen exceeded 25 mg/L, the rate of denitrification was negatively correlated with the maximum measured nitrite-nitrogen concentration. The stoichiometric carbon requirement was not correlated to any parameters believed to influence carbon consumption. After complete denitrification was achieved residual sCOD was still measured, which could not be identified as VFAs. Batch aerobic treatment of denitrified effluent resulted in a 60 to 70 % removal of the residual sCOD when allowed to react for 8 days. It was further determined that the residual sCOD exerted an oxygen of 5.81 on g COD/g C. Additional studies were conducted to maximize sCOD production during fermentation. Increasing the fermentation temperature from 28 oC to 40 oC facilitated a 36 % increase in the specific sCOD production rate (g sCOD/ g fish solids applied). In addition to sCOD production, ammonia production increased 20 % when the fermentation was conducted at the elevated temperature. An analysis comparing the cost of methanol addition to support denitrification to the cost associated with fermenting waste fish solids indicated that supplementing fermentation products with methanol resulted in the least costly strategy for promoting denitrification of an aquaculture waste stream. / Master of Science

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Treatment efficiency in a constructed wetland is related in part to the amount of time that a wastewater remains in the system. Current design methods idealize the system as a plug flow reactor and use a "residence time" based solely on the volume of the cell and the flow rate. Under this assumption, every element of wastewater entering the wetland cell experiences the same residence time. It is understood that this idealization ignores the existence of longitudinal dispersion, short circuiting and stagnant regions within the wetland cell. The result of these phenomena is a distribution of residence times. In other words, portions of the effluent exit the cell earlier than predicted, resulting in undertreatment, and portions exit late, resulting in excess treatment. The average concentration of treated wastewater at the outlet is a function of this distribution and the reaction kinetics associated with the waste. The overall effect of a distribution of residence times is reflected in a reduction of treatment efficiency at the outlet. Hydraulic regimes of constructed wetland systems were investigated at a pilot project site providing tertiary treatment of a pulp mill wastewater. Two vegetation types, bulrush and cattail, were investigated and compared to nonvegetated and rock-filter cells with identical configurations. Tracer studies used a fluorescent dye and were performed over the course of a year. Dye was input as a pulse at the inlet end of the cell and sampled over time at the outlet end to obtain concentration breakthrough curves. From these curves, time to peak, actual mean detention times, degree of dispersion, and extent of dead space were calculated, as well as predicted treatment efficiency. Results indicated varying degrees of dispersion, short circuiting, and dead space in the individual cells. Analysis of the residence time distributions provided estimates of the "active" volume of the treatment cell and the degree of short circuiting in the system. Effective volume of the planted cells ranged from 15 to 25% of full volume. Early arrivals of the peaks of the distributions, indicative of short circuiting, ranged from 30% to 80% of the theoretical detention times. A first order treatment model and a kinetic coefficient, k, were assumed, and corresponding treatment efficiencies were compared to the theoretical treatment of an ideal plug flow reactor. Reduced treatment efficiencies for the planted systems ranged from 2 to 20 %, by this estimation. Many references attempt to analyze wastewater treatment systems by refering to two models: dispersed plug flow and an approximation of tank-in-series. These models were investigated as potential descriptions of the hydraulic regime present in constructed wetlands. Residence time distributions of the constructed wetlands in this study indicated flow was not exclusively dispersed plug flow. This simplified model does not account for the exchange of material with "dead" space in the wetland cell. The data suggest a combination model of dispersed plug flow with a transient storage zone component may be more appropriate. / Graduation date: 1994

Ph.D. (Biochemistry) / Please refer to full text to view abstract

The culture of the floating aquatic plant, duckweed (Lemna minor), as an agent of domestic sewage treatment was studied in a clarification lagoon at Duncan, British Columbia, during the summer of 1986. Duckweed was grown in plastic fabric tanks (3700 L volume, 1.85 m deep, 2.25 m² water surface area) receiving 290 L of sewage per day or 12.8 d hydraulic retention time. Three treatments were tested: cropped duckweed, uncropped duckweed, and no duckweed. Water quality, plant growth and tissue composition were monitored on the basis of weekly sampling. Removals of VSS, COD, total-N and total-P were greater in the presence than in the absence of duckweed. Unmeasured imports of N and P masked the effect of plant uptake on reducing nutrient concentrations in the tank effluents. Sustainable duckweed yields were possible at both cropping rates, despite a severe infestation of aphids. Dry matter yields of 2.0 g/m².d and 6.4 g/m².d were obtained at the 15%/week and 50%/week cropping rates, respectively. Duckweed contained 6.1 - 6.4% N and 1.1 - 1.4% P (dry wt.). Plant harvest removed 0.14 g N/m².d and 0.03 g P/m².d at the 15%./week and 0.31 g N/m².d and 0.07 g P/m².d at the 50%/week cropping rates. Cropping increased the fraction of total-N and total-P loading that could be removed via plant uptake. Performance of the experimental treatments is analyzed in the light of concentration data, mass balances, and mass flux estimations. Possible sources of unmeasured N and P imports are discussed, and recommendations for future research are provided. The results suggest that duckweed may hold promise under certain conditions as a means of polishing sewage lagoon effluent. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Call number: LD2668 .T4 1986 B46 / Master of Landscape Architecture / Landscape Architecture/Regional and Community Planning

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Civil Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Civil Engineering / Master / Master of Philosophy

Enrichment cultures of microorganisms separated from soil contaminated with pentachlorophenol and creosote were able to grow on and degrade phenol (300 mg 2-chlorophenol (100 mg L⁻¹), or 4-chlorophenol (100 mg L⁻¹) when added as the sole carbon source, but were unable to degrade 3-chlorophenol (100 mg L⁻¹) even after more than 127 days of incubation. Phenol biodegradation by enrichment cultures was completely inhibited by temperatures at or above 37 °C or phenol concentrations greater than 1,200 mg L⁻¹. Phenol degradation rates were reduced in the absence of an inorganic nitrogen source. Two species of gram-negative bacterial isolates from this soil degraded 300 mg L⁻¹ phenol in three to twelve days. A yeast isolate degraded 300 mg L⁻¹ phenol more quickly, in one to three days. No isolates were found that degraded any of the chlorinated compounds. Phenol biodegradation by the yeast was completely inhibited by substrate concentrations greater than 1,000 mg L⁻¹; it was partly inhibited by low dissolved-oxygen concentrations, substrate concentrations greater than 500 mg L⁻¹, and the presence of alternative carbon sources such as acetate or glucose. Acetate also inhibited yeast growth in the presence of phenol, while glucose stimulated it. The addition of yeast extract or thiamin stimulated yeast growth and phenol degradation by the yeast. In enrichment cultures, growth factors were provided to yeast by other microorganisms. Maximum rates of phenol degradation by yeast and enrichment cultures were comparable, often greater than 300 mg L⁻¹ phenol per day. Doubling times for yeast growing on phenol were generally from three to five hours. The rapid rates of growth and phenol degradation by isolates and enrichments suggest that biodegradation of phenol in the subsurface should not be substrate limited. Rather the transport of dissolved oxygen by advection/dispersion or vertical diffusion should limit phenol degradation by aerobic metabolic pathways in groundwater.