Nitrogen is one of the major elements essential for plant growth. It is the element most prone to depletion by cultivation and is usually found deficient in soils. In successful farming the problem of nitrogen supply is of special importance because plants need it in large amounts, it is fairly expensive to supply, and it is easily lost from the soil.

Made available in DSpace on 2016-08-17T17:11:04Z (GMT). No. of bitstreams: 1 DISSERTACAO_GABRIEL CARDOSO NEVES.pdf: 3003386 bytes, checksum: a66fc84507d8a67ed01e8957922250cd (MD5) Previous issue date: 2015-05-05 / FUNDAÇÃO DE AMPARO À PESQUISA E AO DESENVOLVIMENTO CIENTIFICO E TECNOLÓGICO DO MARANHÃO / The objectives of this study were to determine the effect of different levels of nitrite (NO2 -) associated with calcium (Ca2+) in the water on the performance, biochemical and hematological parameters of jundiá (Rhamdia quelen). One hundred and sixty animals were stored in 16 boxes (n = 10) of 40 liters with constant aeration and kept in a water recirculation system with UV filter for 60 days. The design was completely randomized with 4 treatments and 4 replications in a factorial design with two levels of NO2 - (0,05 e 1,4 mg L-1) x 2 levels of Ca2+ in water (5 e 20 mg L-1). Fish (8.9±0.2 g and 15.0±0.8 cm) were fed with the diet (32% CP and max. 2.0% Ca2+) twice a day at home. Was done daily removal of waste by siphoning, and 80% of the water was replaced by another with nitrite and calcium levels previously set. The nitrite and calcium levels were maintained by the addition of sodium nitrite (NaNO2) and calcium carbonate (CaCO3), respectively. They evaluated: the growth performance, biochemical and hematological parameters for juvenile catfish (Rhamdia quelen). The final survival was not affected by nitrite levels associated with Ca2+. At 30 days, it was observed that there was no change (P>0.05) in weight gain, biomass, specific growth rate and feed conversion between the analyzed treatments. At 60 days, there was an increase (P<0.05) in weight gain, biomass and specific growth rate for animals of the control treatment in relation to the treatment high NO2 - and Ca2+ down, and for treatment low NO2 - and Ca2+ high in relation to the treatment high NO2 - and Ca2+ high. At the end of the experiment, it was found that the feed intake was higher of the treatment low NO2 - and Ca2+ high in relation to the treatment high NO2 - and Ca2+ high. No change (P>0.05) for converting food to end the 60-day trial. No change (P>0.05) in the levels of lactate and glycogen in the liver. The treatment showed control levels (P<0.05) higher protein in the liver compared to fish subjected to high Ca2+ and NO2 - low. Glucose levels in fish liver were higher (P<0.05) in the control treatment in relation to the treatments low NO2 - and Ca2+ high and high NO2 - and Ca2+ down. The levels of lactate and glycogen in muscle showed a lower (P<0.05) in the control treatment in relation to the treatment high NO2 - and Ca2+ down. The protein level in the muscle was lower (P<0.05) in treatment high NO2 - and Ca2+ high in relation to treatment low NO2 - and Ca2+ high and treatment high NO2 - and Ca2+ down. Glucose levels in the muscle had a higher (P<0.05) of the control treatment in relation to the treatment high NO2- and Ca2+ low, and higher of the treatment low NO2- and Ca2+ high in relation to the treatment high NO2- and Ca2+ high. The increase in hardness does not favored animals subjected to high levels of nitrite in relation to the hemoglobin levels. Fish exposed to high NO2 - and Ca2+ high, showed a reduction in this parameter for the processing low NO2 - and Ca2+ high (T2). This result may be an indication that there was blood hemoglobin oxidation in methemoglobin, causing poisoning in fish. Thus, the use of 20 mg L- 1Ca2+ in water has no positive effect in reducing the toxicity of nitrite in relation to performance, biochemical and hematological parameters for juvenile catfishes (Rhamdia quelen). / Os objetivos neste trabalho foram determinar o efeito de diferentes níveis de nitrito (NO2 -) associado ao cálcio (Ca2+) na água sobre o desempenho, parâmetros bioquímicos e hematológicos em juvenis de jundiá (Rhamdia quelen). Cento e sessenta animais foram estocados em 16 caixas (n=10) de 40 litros com aeração constante e mantidos em um sistema de recirculação de água com filtro U.V durante 60 dias. O delineamento utilizado foi o inteiramente casualizado com 4 tratamentos e 4 repetições em esquema fatorial com 2 níveis de NO2 - (0,05 e 1,4 mg L-1) x 2 níveis de Ca2+ na água (5 e 20 mg L-1). Os peixes (8,9±0,2 g e 15,0±0,8 cm) foram alimentados com ração extrusada (32% PB e máx. 2,0 % de Ca2+) duas vezes ao dia à vontade. Diariamente foi feito a retirada dos resíduos por sifonagem, e 80% da água foi substituída por outra com níveis de nitrito e cálcio previamente ajustados. Os níveis de nitrito e cálcio foram mantidos por meio da adição de nitrito de sódio (NaNO2) e carbonato de cálcio (CaCO3), respectivamente. Foram avaliados: o desempenho zootécnico, os parâmetros bioquímicos e hematológicos para juvenis de jundiá (Rhamdia quelen). A sobrevivencia final não foi afetada pelos niveis de nitrito associado ao Ca2+. Aos 30 dias, observou-se que não houve alterações (P>0,05) no ganho de peso, biomassa, taxa de crescimento específico e conversão alimentar entre os tratamentos analisados. Aos 60 dias, observou-se aumento (P<0,05) no ganho de peso, biomassa e taxa de cresimento específico para os animais do tratamento controle em relação ao tratamento alto NO2 - e Ca2+ baixo, e para o tratamento baixo NO2 - e Ca2+ alto em relação ao tratamento alto NO2 - e Ca2+ alto. Ao final do período experimental, observou-se que o consumo de ração foi maior no tratamento baixo NO2 - e Ca2+ alto em relação ao tratamento alto NO2 - e Ca2+ alto. Não houve alterações (P>0,05) para a converção alimentar ao final dos 60 dias experimentais. Não houve alterações (P>0,05) nos níveis de lactato e glicogênio no fígado. Os animais do tratamento controle apresentaram níveis (P<0,05) mais elevados de proteína no fígado em relação aos peixes submetidos a alto NO2 - e Ca2+ baixo. Os níveis de glicose no fígado dos peixes foram maiores (P<0,05) no tratamento controle em relação aos tratamentos baixo NO2 - e Ca2+ alto e alto NO2 - e Ca2+ baixo. Os níveis de lactato e glicogênio no músculo apresentaram-se menor (P<0,05) no tratamento controle em relação ao tratamento alto NO2 - e Ca2+ baixo. O nível de proteína no músculo foi menor (P<0,05) no tratamento alto NO2 - e Ca2+ alto em relação ao tratamento baixo NO2 - e Ca2+ alto e ao tratamento alto NO2 - e Ca2+ baixo. Os níveis de glicose no músculo apresentaram-se maior (P<0,05) no tratamento controle em relação ao tratamento alto NO2 - e Ca2+ baixo, e maior (P<0,05) no tratamento baixo NO2 - e Ca2+ alto em relação ao tratamento alto NO2 - e Ca2+ alto. O aumento da dureza não favoreceu os animais submetidos a elevados níveis de nitrito em relação ao niveis de hemoglobina. Os peixes expostos a alto NO2 - e Ca2+ alto, apresentaram uma redução neste parâmetro em relação ao tratamento baixo NO2 - e Ca2+ alto (T2). Tal resultado pode ser um indicativo de que houve oxidação da hemoglobina do sangue em metahemoglobina, causando intoxicação nos peixes. Sendo assim, a utilização de 20 mg L- 1Ca2+ na água não apresenta efeito positivo na redução da toxidez do nitrito em relação ao desempenho, parâmetros bioquímicos e hematológicos para juvenis de jundiá (Rhamdia quelen).

Research was performed at a pilot-scale wastewater treatment plant operating an adsorption/bio-oxidation (A/B) process at 20C. The study compared B-Stage performance under DO Control, Ammonia Based Aeration Control (ABAC), and Ammonia vs. NOx (AvN) control. AvN in 1) fully-intermittent and 2) intermittently-aerated MLE configurations was compared to DO Control and ABAC, each with continuous aeration, in an MLE configuration. The study also examined operation of each aeration strategy with two different feed types: A-Stage effluent (ASE) and primary clarifier effluent (PCE). Operating modes were compared on the basis of nitrogen removal performance, COD utilization efficiency for denitrification, and alkalinity consumption. AvN was found to provide comparable nitrogen removal performance to DO Control and ABAC. The highest nitrogen removal performance was seen when operating DO Control (81.4 ± 1.2%) and ABAC (81.1 ± 1.2%) with PCE. High nitrogen removal efficiency (77.5 ± 6.1%) was seen when fully-intermittent AvN operation was fed ASE containing a high particulate COD fraction. A high effluent nitrite accumulation ratio (NAR = NO2-/(NO2-+NO3-)) was seen during this period (46 ± 15%) accompanied by the out-selection of Nitrospira. Feeding effluent from AvN control to an Anammox MBBR improved removal efficiency. Increased soluble COD loading resulted in greater nitrogen removal with strategies operating in an MLE configuration while particulate COD was found to be important for processes where removal was designed to occur in downstream reactors. Efficiency of COD for denitrification was found to vary based on the amount and type of influent COD; however AvN in an MLE configuration was found to use COD more efficiently than fully-intermittent AvN. In either configuration, AvN required less alkalinity addition than DO Control or ABAC. High sCOD concentrations in PCE led to increased nutrient removal as compared to ASE but increased heterotrophic growth and mixed liquor concentrations in the B-Stage making the A-Stage an attractive option for its ability to control the C/N ratio fed to BNR processes. / Master of Science