Water management practices to reduce mass discharge are a major point of concern for aquaculture producers. This study assessed effects of consecutive low-grade weirs on chemical retention and settling of aquaculture pond effluent in a single drainage ditch. Two control and nine treatment discharges were conducted September - October 2012. Control discharge dissolved inorganic phosphorus (DIP) load increased 154%, whereas total inorganic phosphorus (TIP), ammonia, and nitrate loads decreased (47%, 43%, and 63%, respectively). Treatment discharge nutrient loads decreased across all analytes (80% DIP, 86% TIP, 89% ammonia, 89% nitrate). However, control and treatment discharges concentrations of DIP and nitrate increased, whereas TIP and ammonia concentrations decreased. All discharges reduced total and volatile suspended solid loads 72% - 94%, with removal rates of 0.02 ± 0.01 mg/L/min total and 0.02 ± 0.001 mg/L/min volatile suspended solids. Results indicate ditches fit with low-grade weirs may be an innovative management practice.

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During the water quality and sludge characterization phase, average effluent quality over the course of a day was not found to be impaired during a 7-month sampling and monitoring study at the three trout farms. However, effluent quality was found to change significantly during times of high farm activity (i.e. feeding, harvesting, cleaning, etc.). Normalized Total Suspended Solids (TSS) concentrations were found to be as high as 115 mg/l during harvesting and 63 mg/l during feeding. Solids characterization studies proved farm waste solids degrade over time and that their particle size distributions are a function of the feed size and activity of a certain raceway. Waste solids accumulation studies proved that the solids removal efficiency of farm sediment traps were very low, and after a certain period of time, they reached capacity due to particle scouring. A pilot plant was constructed in the water and sludge treatability phase to prove a baffled settling scheme was sufficient to treat average and peak TSS concentrations during a normal workweek. The study found optimal TSS removals at detention times of 15-20 minutes, and overflow rates of 77.4 – 48.9 m3/m2·d. Given economic, spatial, and operational constraints, sedimentation was found to be the most feasible treatment technology for raceway-system trout farms. / Master of Science

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The boundary integral technique was implemented in a computer code for the general static analysis of three dimensional elastic solids. The was based on a formulation of the problem in which the governing boundary equation is developed from the known solution to Kelvin's problem, by the application of Betti's reciprocal relationship. Modeling the boundary of the region being analyzed with plane elements and assuming the tractions and displacements constant across these elements leads to a set of simultaneous algebraic equations approximating the boundary integral equation. Numerical techniques are used in the computer code to assemble and solve this set of equations. The operation of this code was demonstrated by the solution of several example problems. The results of these problems show the code to be successful. It's practical application however is limited due to the large solution time required. This time would be significantly reduced if a more efficient equation solver were employed. The time requirement could be a severe limitation when a relatively large number of elements is needed to model displacement gradients. The development of an element based on linear or higher order variation of displacements would greatly reduce the required mesh size in this case and thus the solution time.

Effective heat transfer through a bed of particulate solid largely affects the production rate and the process stability in an extrusion process. Most classical models in single screw extrusion treat the solids bed as a continuum behaving as an elastic plug or fluid while neglecting the discrete nature of the particles and the presences of the fluid. The heat transfer within the solids bed in these models is calculated based on thermophysical properties of the bulk system without consideration for the presence of the interstitial fluid. From a practical point of view, experimental measurements of solids bed heat transfer within a rotating screw, particularly cross channel, as the bed moves down the length of the solids conveying zone are impossible to perform. A new device was designed to model the radial compressive stresses and shear stresses on a solids bed of plastics, similar to the environment within the screw channel of a single screw extruder. This device enables the user to visualize the nature of the solids bed under different experimental conditions through a transparent wall. Also, the device provides ways to explore the heat transfer in a solids bed under different conditions by embedded thermocouples on the top or through the front wall of the containing chamber. The results reported in this study have shown that the discrete nature of the solid bed has a strong affect on the heat transfer within the bed. The rate of heat transfer within the different beds of polymer did not appear dominated by the thermophysical properties of the materials. Rather, the evidence supports that conduction through the pseudo-static interstitial fluid (i.e. air) dominated the rate at which a polymer bed heats up; a finding similarly found for the sintering of powdered metals and ceramics in the literature. This finding would imply that differences in melting rates found in extruders are not related to the heat transfer in the solids bed; however, this statement only holds true so long as the granules making up the bed remain static (i.e. plug-like) and do not circulate within the screw channel. Quite interestingly, pellet circulation within the solid bed was observed in LLDPE over a range of test conditions. This pellet circulation resulted in enhanced heat transfer within the bed of LLDPE (a raise of 10°C) compared to PS and PP. PP exhibited pellet circulation but only over a small window of operation. Different ways to improve heat transfer within solid bed were subsequently tested in this project, such as starve feed, forced convection and spherical particle. From this work, improved understanding of heat transfer in the solids conveying zone of a single screw extruder was gained. / Thesis / Master of Applied Science (MASc)