Design characteristics of showering aeration system

The showering aeration system (SAS) was designed and its performance was evaluated by conducting the aeration experiments in a tank of dimension 2 × 4 × 1.5 m. Initially, the aeration experiments were conducted to optimize the radius of curvature of the SAS with different values, such as = 0, 5, 10, 15, and 20 mm, and maintain other geometric parameters, i.e. number of holes in the shower (); height of water fall (H); diameter of the shower hole (d); volume of water under aeration (V) and water flow rate (Q) as constants. The optimum radius of curvature () was found to be 10 mm. The aeration experiments were further conducted with four different non-dimensional geometric parameters such as the number of holes , the ratio of the height of water fall to the length of shower arm the ratio of the diameter of the hole to the length of shower arm and the ratio of the volume of water to the cube of the length of shower arm The Response Surface Methodology and Box–Behnken Design were used to optimize the non-dimensional geometric parameters of the SAS to maximize the Non-Dimensional Standard Aeration Efficiency. The result indicates that the maximum NDSAE of 16.98 × 106 was obtained from the SAS performance at = 80; = 2; = 4 and = 48. HIGHLIGHT The optimized non-dimensional geometric parameters (H/l; d/l; V/l3; n) for the showering aeration system were experimentally validated, and the final NDSAE value was found to be 16.98 × 106 against the predicted NDSAE value of 17.70 × 106.

Experimental Oxygen Mass Transfer Study of Micro-Perforated Diffusers

We studied new micro-perforated diffuser concepts for the aeration process in wastewater treatment plants and evaluated their aeration efficiency. These are micro-perforated plate diffusers with orifice diameters of 30 µm, 50 µm and 70 µm and a micro-perforated tube diffuser with an orifice diameter of 50 µm. The oxygen transfer of the diffuser concepts is tested in clean water, and it is compared with commercial aerators from the literature. The micro-perforated tube diffuser and micro-perforated plate diffusers outperform the commercial membrane diffusers by up to 44% and 20%, respectively, with regard to the oxygen transfer efficiency. The most relevant reason for the improved oxygen transfer is the fine bubble aeration with bubble sizes as small as 1.8 mm. Furthermore, the more homogenous cross-sectional bubble distribution of the micro-perforated tube diffuser has a beneficial effect on the gas mass transfer due to less bubble coalescence. However, the pressure drop of micro-perforated diffusers seems to be the limiting factor for their standard aeration efficiencies due to the size and the number of orifices. Nevertheless, this study shows the potential for better aeration efficiency through the studied conceptual micro-perforated diffusers.

PERFORMANCE EVALUATION OF LOCALLY FABRICATED MECHANICAL SURFACE AERATOR

Experimental analysis for a fabricated Low-Speed surface aerator that can be used in wastewater and water treatment is presented in this research. The designed impeller configuration was tested to determine its power consumption, standard oxygen transfer rate (SOTR), and standard aeration efficiency (SAE). Impeller oxygen transfer and power consumption in a scaled laboratory tank were measured during aeration phase. The impeller was consisting of 8 inclines flat blades with an angle of 45° from center of the disc, was operated at 3 different immersion depths and 5 different rotational speeds for examining the impact of such factors on impeller efficiency. The results recorded that the best standard aeration efficiency for this configuration is (0.206 Kg. O2/KW.hr) at 120rpm and 7cm depth of the submersion, i.e. submersion depth to impeller diameter (h/D) ratio equals 0.175. Submergence depth increase beyond this limit would result in SAE decrease and definitely result into more power consumption.

Influence of Air Supply Height on Sleep Comfort Through Computational Fluid Dynamics Simulation

Taking the bed in the bedroom as an air-conditioning system (ACS), this paper attempts to disclose the influence of air supply height (ASH) on sleep comfort. Specifically, a computational fluid dynamics (CFD) model was established to simulate the air temperature distribution, air speed, and carbon dioxide content (CDC) indoor at five ASHs of the ACS. The simulation results were compared with lab data. On this basis, the aeration efficiency (AE), temperature regulation risk (TRR), and energy-use factor (EUF) of the ACS were analyzed under different working conditions, and the overall efficacy of the ACS was assessed comprehensively by the technique for order of preference by similarity to ideal solution (TOPSIS).

Prediction of standard aeration efficiency of propeller diffused aeration system using response surface methodology and artificial neural network

Aeration experiments were conducted in a masonry tank to study the effects of operating parameters on standard aeration efficiency (SAE) of a propeller diffused aeration (PDA) system. The operating parameters include the rotational speed of shaft (N), submergence depth (h), and propeller angle (α). The response surface methodology (RSM) and artificial neural network (ANN) were used for modelling and optimizing the standard aeration efficiency (SAE) of a PDA system. The results of the both approaches were compared for their modelling abilities in terms of coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE), computed from experimental and predicted data. ANN models were proved to be superior to RSM. The results indicate that for achieving the maximum standard aeration efficiency (SAE), N, h and α should be 1,000 rpm, 0.50 m, and 12°, respectively. The maximum SAE was found to be 1.711 kg O2/ kWh. The cross-validation results show that the best approximation of optimal values of input parameters for maximizing SAE is possible with a maximum deviation (absolute error) of ±15.2% between the model predicted and experimental values.

Prediction of aeration efficiency of parshall and modified venturi flumes: application of soft computing versus regression models

In this study, the potential of soft computing techniques namely Random Forest (RF), M5P, Multivariate Adaptive Regression Splines (MARS), and Group Method of Data Handling (GMDH) was evaluated to predict the aeration efficiency (AE20) at Parshall and Modified Venturi flumes. Experiments were conducted for 26 various Modified Venturi flumes and one Parshall flume. A total of 99 observations were obtained from experiments. The results of soft computing models were compared with regression-based models (i.e., MLR: multiple linear regression, and MNLR: multiple nonlinear regression). Results of the analysis revealed that the MARS model outperformed other soft computing and regression-based models for predicting the AE20 at Parshall and Modified Venturi flumes with Pearson's correlation coefficient (CC) = 0.9997, and 0.9992, and root mean square error (RMSE) = 0.0015, and 0.0045 during calibration and validation periods. Sensitivity analysis was also carried out by using the best executing MARS model to assess the effect of individual input variables on AE20 of both flumes. Obtained results on sensitivity examination indicate that the oxygen deficit ratio (r) was the most effective input variable in predicting the AE20 at Parshall and Modified Venturi flumes.

THE PERCENTAGE OF OXYGEN ABSORPTION BY VANNAMEI SHRIMP (LITOPENAEUS VANNAMEI) WHICH IS SUPPORTED BY THE PADDLEWHEEL

<p>A dynamic model was used to obtain optimal value or amount in the application of paddlewheel. Stella 9.1.4 software programing was employed to find relationships among parameters. The aims of this reasearch was to determine the percentage of oxygen uptake by vannamei shrimp (Litopenaeus vannamei) which is supported by 1 paddlewheel. The result showed that the optimal number of paddlewheel was 1 paddlewheel with Standart Aeration Efficiency was 1,31 kgO2/kWh. The percentage of oxygen absorption on vannamei shrimp until final cultivation was 24% during the cultivation, the percentage of oxygen absorption on vannamei shrimp had increased. In this research, total oxygen demand was 567 ppm, shrimp production was 1054,88 kg, the amount of feed was 2278,1 kg with a pond area was 600 m2, stocking density was 133 PL/m2 during a cultivation period of 98 days.<br />Keyword : Paddlewheel, Oxygen, Vannamei shrimp (Litopenaeus vannamei)</p>