Acute ammonia toxicity in rainbow trout was studied. This was carried out by injecting fish with various concentrations of ammonia dissolved in isotonic saline. In order to approximate conditions of natural toxicity, where ammonia would enter the fish at the gills, without the additional problems of environmental factors, the ammonium solutions were injected via a cannula implanted in the dorsal aorta. To determine if a differential toxicity existed in fish in relation to high pH and low pH ammonium solutions, ammonium bicarbonate and ammonium chloride were chosen for injection. Hydrogen ion, and total ammonia, concentrations were measured in blood sampled from the dorsal aorta, both before and after injection. In order to determine if, during the course of the injection, normal excretion rates would remove all of the injected ammonia, total ammonia and hydrogen ion concentrations were measured in blood sampled from both the dorsal and ventral aortae, and rates of extraction of ammonia from blood at the gills were calculated. Ammonia is toxic to fish. There was no significant difference between the dose of NH₄Cl and NH₄HCO₃ which killed fish. Therefore, unlike mammals, fish exhibited no differential toxicity to the ammonium compounds tested. Injection of NH₄Cl decreased pHa and injection of NH₄HCO₃ increased pHa. Both compounds increased the total ammonia concentration in the blood. Although in water the fraction of ammonia which exerts the toxic effects is unionized ammonia, within the fish it is the ionized fraction which exerts the toxic effects. The same dose of ammonium killed fish, but NH₄HCO₃-injected fish which survived had a much higher concentration of unionized ammonia in the blood than NH₄Cl-injected fish which died. Ammonia extracted from the blood in control fish was about one-fifth the amount which killed fish. This, together with the measured increases in blood ammonia following injection, demonstrate that, although ammonia is a normal excretory product of rainbow trout, the trout cannot increase excretion rates sufficiently to rid themselves of an ammonia load. Symptoms observed in fish following injection of ammonium solutions led to the conclusion that ammonia acts at the neural level. / Science, Faculty of / Zoology, Department of / Graduate

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Numerous wastewater treatment processes are currently available for nitrogen removal or ammonia conversion to nitrate. Those that are economically feasible rely mostly on microbiological processes, which are only effective when the microorganisms remain in a healthy state. If a biological process upset was to occur, due to a toxic shock load or cold weather, it may result in a discharge of ammonia or total nitrogen into the receiving water body. The impact of such a discharge could have deleterious effects on aquatic life or human health. The main objective of the breakpoint pilot study was to define optimum breakpoint pilot plant operating conditions which could then be applied to the design of a full scale breakpoint facility and serve as an emergency backup to biological nitrification. A pilot study was built on site at the Upper Occoquan Sewage Authority's Regional Water Reclamation Facility in Centreville Virginia. Testing was conducted in two phases (I and II) over a two year period in order to determine the operating conditions at which the breakpoint reaction performed best. Tests were performed during Phase I to determine the optimum operating pH, Cl₂:NH₃-N dose ratio, S0₂:Cl₂ dose ratio, and the minimum detention time for completion of the breakpoint reaction. Other testing done during Phase I included several special studies; including examination of appropriate analytical methods for monitoring breakpoint reactions, and investigation of the breakpoint reaction by-product nitrogen trichloride. Phase II testing examined how varying breakpoint operating temperatures, varying influent ammonia concentrations, higher influent organic nitrogen concentrations, and higher influent nitrite concentrations influenced the performance of the breakpoint pilot operation. Averages of data from operation at three different rapid mix pHs (7.0, 7.5, and 8.0) showed that pilot performance (i.e., ammonia oxidation) improved and the reaction was more stable at the higher operating pHs 7.5 and 8.0. Examination of dose ratios used during the study showed that the ideal operating ratios for this particular water was around 8:1 Cl₂:NH₃-N for the breakpoint reaction and 1.3:1 S0₂:Cl₂ for the dechlorination reaction. Although detention times for completion of the breakpoint reaction varied with pilot influent temperature, it generally required around 30-35 minutes to reach ammonia concentrations of < 0.2 mg/L NH₃-N at 8-12°C. Completion of the breakpoint reaction was found to be quickest at 20°C (the highest water temperature tested at the pilot). The tests of varying influent ammonia concentrations showed that although higher influent ammonia concentrations (11.0 mg/L) resulted in faster ammonia oxidation rates initially, the pilot operated better and had the same final performance results when the influent ammonia was lowered. Increasing the organic nitrogen concentrations (~ 1.0 mg/L) in the pilot influent resulted in a slightly higher Cl₂:NH₃-N dose ratio needed to reach breakpoint, a higher S0₂:Cl₂ dose needed to dechlorinate, and resulted in the formation of numerous disinfection byproducts. Increasing the nitrite concentration in the pilot influent increased the chlorination dose requirement. / Master of Science

A new model for the complex dielectric constant, ε, of aqueous ammonia (NH4OH) has been developed based on laboratory measurements in the frequency range between 2-8.5 GHz for ammonia concentrations of 0-8.5 %NH3/volume and temperatures between 277-297 K. The new model has been validated for temperatures up to 313 K, but may be consistently extrapolated up to 475 K and ammonia concentrations up to 20 %NH3/volume. The model fits 60.26 % of all laboratory measurements within 2σ uncertainty. The new model is identical to the Meissner and Wentz (2004) model of the complex dielectric constant of pure water, but it contains a correction for dissolved ammonia. A description of the experimental setups, uncertainties associated with the laboratory measurements, the model fitting process, the new model, and its application to approximating jovian cloud opacity for NASA's Juno mission to Jupiter are provided.