scholarly journals Modelagem simplificada do fósforo total em lagos e reservatórios brasileiros

Revista DAE ◽  
2019 ◽  
Vol 221 (68) ◽  
pp. 142-156
Author(s):  
Arthur Toné ◽  
Iran Lima Neto
Keyword(s):  
Water Temperature ◽  
Residence Time ◽  
Extreme Values ◽  
High Water ◽  
Temporal Variations ◽  
Water Volume ◽  
Hydraulic Residence Time ◽  
Decay Coefficient ◽  
Proposed Model ◽  
Lakes And Reservoirs

Resumo O fósforo é considerado o principal fator responsável pela eutrofização de lagos e reservatórios. No presente estudo, utilizou-se um modelo transiente de mistura completa para analisar a dinâmica do fósforo em 40 lagos e reservatórios localizados nas regiões Nordeste, Sudeste e Centro-Oeste do Brasil. Os resultados con- firmaram a dependência do coeficiente de decaimento de fósforo com o inverso da raiz quadrada do tempo de residência hidráulica. No entanto, em virtude da elevada temperatura da água dos lagos e reservatórios do Nordeste, esse coeficiente assumiu valores cerca de duas vezes superiores àqueles observados em regiões de clima tropical. Por outro lado, devido à alta variabilidade de temperatura dos lagos e reservatórios do Sudes- te, o coeficiente oscilou entre valores extremos observados em regiões de clima temperado e semiárido. Em virtude disso, propôs-se uma equação geral para calcular o coeficiente de decaimento de fósforo como uma função não apenas do tempo de residência hidráulica, mas também da temperatura da água. Após validação e análise de sensibilidade do modelo proposto, o mesmo foi aplicado a um reservatório hipotético sujeito a variações temporais de volume, vazão, carga e temperatura da água. Espera-se que este modelo simplificado possa auxiliar na gestão de lagos e reservatórios brasileiros. Palavras-chave: Eutrofização. Temperatura. Qualidade da água. Abstract Phosphorus is considered the main factor responsible for eutrophication of lakes and reservoirs. In the present study, a transient complete mixing model was used to analyse phosphorus dynamics in 40 lakes and reservoirs located in the Northeast, Southeast and Central-West regions of Brazil. The results confirmed the dependence of the phosphorus decay coefficient on the inverse of the square root of the hydraulic residence time. However, due to the high-water temperature of the lakes and reservoirs of the Northeast, this coefficient assumed values about two times higher than those observed in regions of tropical climate. On the other hand, due to the high temperature variability of the lakes and reservoirs in the Southeast, the coefficient oscillated between extreme values observed in temperate and semiarid regions. As a result, a general equation was proposed to calculate the phosphorus decay coefficient as a function not only of the hydraulic residence time, but also of the water temperature. After valida- tion and sensitivity analysis of the proposed model, it was applied to a hypothetical reservoir subject to temporal variations of water volume, flow, load and temperature. This simple model will potentially assist in the management of Brazilian lakes and reservoirs. Keywords: Eutrophication. Temperature. Water quality.

A Mathematical Model for the Anaerobic Digestion Process Applied to a Mixture of Night Soil and Septic Tank Sludge

1986 ◽  
Vol 18 (7-8) ◽  
pp. 239-248 ◽  
Author(s):  
Sung Ryong Ha ◽  
Dwang Ho Lee ◽  
Sang Eun Lee
Keyword(s):  
Mathematical Model ◽  
Anaerobic Digestion ◽  
Biomass Concentration ◽  
Gas Production ◽  
Septic Tank ◽  
Volatile Acid ◽  
Hydraulic Residence Time ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Proposed Model

Laboratory scale experiments were conducted to develop a mathematical model for the anaerobic digestion of a mixture of night soil and septic tank sludge. The optimum mixing ratio by volume between night soil and septic tank sludge was found to be 7:3. Due to the high solids content in the influent waste, mixed-liquor volatile suspended solids (MLVSS) was not considered to be a proper parameter for biomass concentration, therefore, the active biomass concentration was estimated based on deoxyribonucleic acid (DNA) concentration in the reactor. The weight ratio between acidogenic bacteria and methanogenic bacteria in the mixed culture of a well-operated anaerobic digester was approximately 3:2. The proposed model indicates that the amount of volatile acid produced and the gas production rate can be expressed as a function of hydraulic residence time (HRT). The kinetic constants of the two phases of the anaerobic digestion process were determined, and a computer was used to simulate results using the proposed model for the various operating parameters, such as BOD5 and volatile acid concentrations in effluent, biomass concentrations and gas production rates. These were consistent with the experimental data.

scholarly journals Surface Water Temperature Predictions at a Mid-Latitude Reservoir under Long-Term Climate Change Impacts Using a Deep Neural Network Coupled with a Transfer Learning Approach

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1109
Author(s):  
Nobuaki Kimura ◽  
Kei Ishida ◽  
Daichi Baba
Keyword(s):  
Climate Change ◽  
Surface Water ◽  
Water Temperature ◽  
Transfer Learning ◽  
Air Temperature ◽  
Climate Models ◽  
Temporal Variations ◽  
Training Data ◽  
Surface Water Temperature

Long-term climate change may strongly affect the aquatic environment in mid-latitude water resources. In particular, it can be demonstrated that temporal variations in surface water temperature in a reservoir have strong responses to air temperature. We adopted deep neural networks (DNNs) to understand the long-term relationships between air temperature and surface water temperature, because DNNs can easily deal with nonlinear data, including uncertainties, that are obtained in complicated climate and aquatic systems. In general, DNNs cannot appropriately predict unexperienced data (i.e., out-of-range training data), such as future water temperature. To improve this limitation, our idea is to introduce a transfer learning (TL) approach. The observed data were used to train a DNN-based model. Continuous data (i.e., air temperature) ranging over 150 years to pre-training to climate change, which were obtained from climate models and include a downscaling model, were used to predict past and future surface water temperatures in the reservoir. The results showed that the DNN-based model with the TL approach was able to approximately predict based on the difference between past and future air temperatures. The model suggested that the occurrences in the highest water temperature increased, and the occurrences in the lowest water temperature decreased in the future predictions.

scholarly journals Forecasting water temperature in lakes and reservoirs using seasonal climate prediction

2021 ◽  
pp. 117286
Author(s):  
Daniel Mercado-Bettín ◽  
Francois Clayer ◽  
Muhammed Shikhani ◽  
Tadhg N. Moore ◽  
María Dolores Frías ◽  
...  
Keyword(s):  
Water Temperature ◽  
Climate Prediction ◽  
Seasonal Climate ◽  
Seasonal Climate Prediction ◽  
Lakes And Reservoirs

A Multi-Period Evacuation Vehicle Routing Problem Model

2014 ◽  
Vol 931-932 ◽  
pp. 578-582
Author(s):  
Sunarin Chanta ◽  
Ornurai Sangsawang
Keyword(s):  
Vehicle Routing ◽  
Public Transportation ◽  
Vehicle Routing Problem ◽  
Programming Model ◽  
High Water ◽  
Mixed Integer ◽  
Routing Problem ◽  
Problem Model ◽  
Proposed Model ◽  
Evacuation Routing

In this paper, we proposed an optimization model that addresses the evacuation routing problem for flood disaster when evacuees trying to move from affected areas to safe places using public transportation. A focus is on the situation of evacuating during high water level when special high vehicles are needed. The objective is to minimize the total traveled distance through evacuation periods where a limited number of vehicles is given. We formulated the problem as a mixed integer programming model based on the capacitated vehicle routing problem with multiple evcuation periods where demand changing by the time. The proposed model has been tested on a real-world case study affected by the severe flooding in Thailand, 2011.

scholarly journals The impact of rotational speed and water volume on textile translational motion in a front-loading washer

2018 ◽  
Vol 89 (16) ◽  
pp. 3401-3410 ◽  
Author(s):  
Hong Liu ◽  
R Hugh Gong ◽  
Pinghua Xu ◽  
Xuemei Ding ◽  
Xiongying Wu
Keyword(s):  
Residence Time ◽  
Rotational Speed ◽  
High Speed ◽  
Translational Motion ◽  
Processing System ◽  
Water Volume ◽  
Motion Path ◽  
Rotational Axis ◽  
Passive Region ◽  
The Impact

Textile motion in a front-loading washer has been characterized via video capturing, and a processing system developed based on image geometric moment. Textile motion significantly contributes to the mass transfer of the wash solution in porous materials, particularly in the radial direction (perpendicular to the rotational axis of the inner drum). In this paper, the velocity profiles and residence time distributions of tracer textiles have been investigated to characterize the textile dynamics in a front-loading washer. The results show that the textile motion varies significantly with the water volume and rotational speed, and that the motion path follows certain patterns. Two regions are observed in the velocity plots: a passive region where the textile moves up with low velocity and an active region where the textile falls down with relatively high speed. A stagnant area in the residence time profile is observed. This corresponds to the passive region in the velocity profile. The stagnant area affects the mechanical action, thus influencing washing efficiency and textile performance. The findings on textile dynamics will help in the development of better front-loading washers.

Non-Markovian model for the study of pitting corrosion in a water pipe system

2015 ◽  
Vol 26 (10) ◽  
pp. 1550119 ◽  
Author(s):  
A. C. P. Rosa ◽  
P. Vaveliuk ◽  
M. A. Moret
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Extreme Values ◽  
Tail Probability ◽  
Markovian Model ◽  
Nonextensive Statistical Mechanics ◽  
Long Tail ◽  
Pipe System ◽  
Proposed Model ◽  
State Regime

The main studies on pitting consist in proposing Markovian stochastic models, based on the statistics of extreme values and focused on growing the depth of wells, especially the deepest one. We show that a non-Markovian model, described by a nonlinear Fokker–Planck (nFP) equation, properly depicts the time evolution of a distribution of depth values of pits that were experimentally obtained. The solution of this equation in a steady-state regime is a q-Gaussian distribution, i.e. a long-tail probability distribution that is the main characteristic of a nonextensive statistical mechanics. The proposed model, that is applied to data from four inspections conducted on a section of a line of regular water service in power water reactor (PWR) nuclear power plants, is in agreement with experimental results.

Temperature effects on bank filtration: redox conditions and physical-chemical parameters of pore water at Lake Tegel, Berlin, Germany

2010 ◽  
Vol 1 (1) ◽  
pp. 55-66 ◽  
Author(s):  
A. Gross-Wittke ◽  
G. Gunkel ◽  
A. Hoffmann
Keyword(s):  
Water Temperature ◽  
High Water ◽  
Nitrate Respiration ◽  
Redox Processes ◽  
Redox Potentials ◽  
Bank Filtration ◽  
Physical Chemical ◽  
Drinking Water Production ◽  
Chemical Conditions ◽  
Sediment Layers

In the city of Berlin, artificial groundwater recharge techniques, such as bank filtration and infiltration ponds, are an important source for drinking water production. Climate change with increasing surface water temperatures can influence the water purification processes during bank filtration mainly due the intensification of metabolic processes leading to a decrease of oxygen and an increase of anaerobic conditions. In Lake Tegel a significant increase of water temperature in the epilimnion of 2.4°C within the last 30 years was recorded. For a better understanding of induced bank filtration at Lake Tegel, redox processes and physical-chemical conditions within the surface sediment layers (0–26 cm depth) at the littoral infiltration zone were investigated. The influence of temperature in the range of 0–25°C on microbial catalysis of redox processes, such as reduction of nitrate and sulphate, was examined during the period March 2004–June 2005. High water temperatures (16–25°C) were accompanied by negative redox potentials (EH=−47 mV) and decreasing Ninorg concentrations, while the amount of ammonia, Mn2 +  and Fe2 +  was rising. This indicates redox processes such as denitrification, Mn4 +  reduction, nitrate respiration and ammonification, as well as Fe3 +  reduction. The reduction of sulphate, however, has not yet become significant at Lake Tegel, but with increasing water temperature, sulphate reduction must be expected.

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