Supersaturation of nitrogen gas caused by artificial aeration in reservoirs /

At head of title: Environmental & Water Quality Operational Studies.

Recent advances in tropical freshwater aquaculture

Several technological advances have been made in tropical freshwater aquaculture during the last three decades. Hatchery production of carp seed was achieved in India and China towards the late 1950's. Channel catfish farming in the U.S. has grown phenomenally. Development of the technology of high density culture using artificial aeration and nutritionally balanced diets has revolutionized freshwater aquaculture, particularly in Israel. Culture of fishes in cages, pens and running water have helped to achieve very high production levels. Considerable research work has been done on fish nutrition during recent years. Investigations on sex control reveal that it is possible to produce a single sex progeny which is more desirable for culture.

Le cycle de l'azote de marais filtrants artificiels : potentiel d'émission de gaz à effet de serre (GES) et exportation de formes azotées

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Desenvolvimento de um sistema computacional integrado para monitoramento de parâmetros físico-químicos da água e análise óptica de gotejadores

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of artificial substrate and night-time aeration on the water quality in Macrobrachium amazonicum (Heller 1862) pond culture

The effects of artificial substrate and night-time aeration on the culture of Macrobrachium amazonicum were evaluated in 12 ponds stocked with 45 prawns m-2. A completely randomized design in 2 × 2 factorial scheme with three replicates was used. The combination of factors resulted in four treatments: with substrate and aeration (SA), with substrate and without aeration (SWA), without substrate and with aeration (WSA) and without substrate and aeration (WSWA). The presence of substrate in SA and SWA treatments reduced suspended particles (seston) by ~17.3% and P-orthophosphate by ~50%. The use of aerator (WSA and SA treatments) significantly (P < 0.05) increased the concentration of dissolved oxygen, suspended particles and nutrients in the pond water. These results indicate that the effect of substrate on turbidity and total suspended solids (TSS) values is opposite to the effect of the aerator. The aerators in semi-intensive grow-out M. amazonicum farming lower water quality because they increased the amount of detritus and nutrients in the pond water. On the other hand, the use of artificial substrate reduces turbidity values, chlorophyll a, TSS and P-orthophosphate concentrations. Therefore, the combination of substrate addition and night-time aeration is not interesting because they have opposite effects. © 2013 John Wiley & Sons Ltd.

The use of mechanical aeration and its effects on water mass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cultivo de camarão com aerador e substrato artificial, identificação de bactérias da wetland construída para o tratamento do efluente

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phenol biodegradation by a microbial consortium: application of artificial neural network (ANN) modelling

In this study, an effective microbial consortium for the biodegradation of phenol was grown under different operational conditions, and the effects of phosphate concentration (1.4 g L-1, 2.8 g L-1, 4.2 g L-1), temperature (25 degrees C, 30 degrees C, 35 degrees C), agitation (150 rpm, 200 rpm, 250 rpm) and pH (6, 7, 8) on phenol degradation were investigated, whereupon an artificial neural network (ANN) model was developed in order to predict degradation. The learning, recall and generalization characteristics of neural networks were studied using data from the phenol degradation system. The efficiency of the model generated by the ANN was then tested and compared with the experimental results obtained. In both cases, the results corroborate the idea that aeration and temperature are crucial to increasing the efficiency of biodegradation.

The use of mechanical aeration and its effects on water mass

Devido ao crescente aumento do uso de aeradores artificiais em sistema de cultivo de peixes e à carência de estudos nesta área, este trabalho avaliou a influência de um aerador tipo propeller diffuser (AR 120) nas variáveis bióticas e abióticas em um viveiro de engorda de peixe. Foram demarcados três pontos de coleta localizados a 5, 10 e 23 m de distância do aerador, durante 15 dias consecutivos, sendo 5 dias antes do uso do aerador, 5 dias com o aerador ligado e 5 dias com o aerador desligado. As variáveis limnológicas estudadas não apresentaram diferenças significativas (P > 0,05) entre os três pontos de coleta, porém, em relação ao uso do aerador, variáveis como temperatura, transparência, pH, oxigênio dissolvido, bicarbonato, CO2 livre, fósforo total, ortofosfato, amônia, nitrato e nitrito diferiram significativamente (P < 0,05) com a agitação mecânica da água. Já a condutividade, alcalinidade, CO2 total e clorofila a não apresentaram diferenças significativas (P > 0,05) com o uso do aerador. A comunidade fitoplanctônica sofreu influência direta do aerador (P < 0,05), dominada pelas Chlorophyta, representando mais de 70% do total de organismos presentes, seguidas das Cyanophyta e Chrysophyta, porém estas últimas tenderam a aumentar após o uso do aerador, uma vez que estes grupos se adaptam rapidamente às mudanças do ambiente.