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Air Diffuser

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A Roig – One of the best experts on this subject based on the ideXlab platform.

  • effect of the aeration system on the levels of Airborne microorganisms generated at wastewater treatment plants
    Water Research, 2008
    Co-Authors: Miguel A Sanchezmonedero, M I Aguilar, R Fenoll, A Roig


    Six different wastewater treatment plants were monitored in order to identify the main bioaerosol sources and to evaluate the effect of the aeration system used in the biological treatment (Air diffusion, horizontal rotors and surface turbine aerators) on the Airborne microorganism levels to which workers may be exposed. Air samples were collected by using a single stage impactor. Total count of mesophilic bacteria was used as the monitoring parameter to compare the impact of the aeration system on generic bacterial bioaerosols rather than a quantitative estimation for pathogens or fecal indicator microbes. In this study, pre-treatment, biological treatment and sludge thickening were the processes that generated the highest amount of bioaerosols. Aeration systems involving mechanical agitation of the wastewater, such as horizontal rotors and surface turbines, generated a larger amount of bioaerosols (between 450 and 4580 CFU/m 3 ) than Air Diffuser aerators (between 22 and 57 CFU/m 3 ). The levels of Airborne bacteria generated by Air Diffusers were very similar to those registered at the background locations (lower than 50 CFU/m 3 ), unaffected by the activities taking place in the wastewater treatment plant. The use of Air Diffusers as an aeration system for the biological treatment would significantly minimise the potential biological hazard that wastewater treatment plant workers may be exposed to.

Hannu Koskela – One of the best experts on this subject based on the ideXlab platform.

  • cfd modelling of an industrial Air Diffuser predicting velocity and temperature in the near zone
    Building and Environment, 2005
    Co-Authors: Gery Einberg, Kim Hagstrom, Panu Mustakallio, Hannu Koskela, Sture Holmberg


    Abstract This article describes experimental and modelling results from CFD simulation of an Air Diffuser for industrial spaces. The main objective of this paper is to validate a manufacturer model of the Diffuser. In the Air Diffuser, the low velocity part is placed on top of a multi-cone Diffuser in order to increase Airflow rates and maximize the cooling capacity of a single Diffuser unit. This kind of configuration should ensure appropriate performance of industrial Air Diffusers, which is discussed briefly at the end of the article. The paper illustrates the importance of a simulation model jointly with the manufacturer’s product model and the grid layout near the ventilation device to achieve accurate results. Parameters for Diffuser modelling were adapted from literature and manufacturer’s product data. Correct specification of Diffuser geometry and numerical boundary conditions for CFD simulations are critical for prediction. The standard k–e model was chosen to model turbulence because it represents the best-known model utilized and validated for Air Diffuser performance. CFD simulations were compared systematically with data from laboratory measurements; Air velocity was measured by ultrasonic sensors. Results show that CFD simulation with a standard k–e model accurately predicts non-isothermal Airflow around the Diffuser. Additionally, smoke tests revealed that the flow around the Diffuser is not completely symmetrical as predicted by CFD. The cause of the observed asymmetry was not identified. This was the main reason why some simulation results deviate from the measured values.

  • evaluation of Air Diffuser flow modelling methods experiments and computational fluid dynamics simulations
    Building and Environment, 2005
    Co-Authors: J R Fontaine, Hannu Koskela, R Rapp, Raimo Niemela


    Abstract The application of computational fluid dynamics to the study of room ventilation presupposes precise specification of the boundary conditions associated with Air Diffusers. The geometric complexity of these devices requires the use of special techniques such as jet-type approximation, relocation of the velocity fixing surface downstream of the device, or even simulation of the flow within the Diffuser. This paper presents a quantitative evaluation of these techniques based on experimental and numerical analysis of the flow of a circular induction Diffuser. All the comparisons are performed by linear regression on the three velocity components obtained at over 900 points. A general methodology for characterising complex Diffusers is deduced from the results.

  • momentum source model for cfd simulation of nozzle duct Air Diffuser
    Energy and Buildings, 2004
    Co-Authors: Hannu Koskela


    Development of simplified models for Air Diffusers is essential for the applicability of CFD-modelling to room Air flow simulation. The geometry of a Diffuser is usually complex and, therefore, it is not possible to use an exact geometrical model in practical CFD-simulations. The model should be simple enough to enable the modelling of a room with several Diffusers. In this study, a simplified model was developed for the nozzle duct Diffuser. The Diffuser consists of a duct, which is partly covered with small nozzles creating high-velocity jets. A complex circulating flow pattern is created between the jets. The room Air enters the flow from the nozzle-free sector and is mixed with the supply Air. The flow field near the Diffuser was investigated with laboratory measurements in order to determine the boundary conditions for the simplified model. The developed model is based on momentum sources describing the induction of secondary Air caused by the jet system. The model was validated with laboratory test cases by comparing the simulation results with measurements. The measured flow patterns in the four test cases with different Archimedes numbers were well reproduced by the simulations.

Ata Allah Nadiri – One of the best experts on this subject based on the ideXlab platform.

  • sequential treatment of paper and pulp industrial wastewater prediction of water quality parameters by mamdani fuzzy logic model and phytotoxicity assessment
    Chemosphere, 2019
    Co-Authors: Sadat Mazhar, Allah Ditta, Laura Bulgariu, Iftikhar Ahmad, Munir Ahmed, Ata Allah Nadiri


    Abstract Recycling of industrial wastewater meeting quality standards for agricultural and industrial demands is a viable option. In this study, paper and pulp industrial wastewater were treated with three biological treatments viz. aerobic, anaerobic and sequential (i.e. 20 days of anaerobic followed by 20 days of aerobic cycle), associated with simulation modeling by Mamdani Fuzzy Logic (MFL) model of some selected parameters. Electric Air Diffuser and minimal salt medium in sealed plastic bottles at control temperature were used for aerobic and anaerobic treatments, respectively. The significant reduction in chemical (COD: 81%) and biological oxygen demand (BOD: 71%), total suspended (TSS: 65%), dissolved solids (TDS: 60%) and turbidity (68%) was recorded during sequential treatment. The treated water was irrigated to determine its phytotoxic effects on seed germination, vigor and seedling growth of mustard (Brassica campestris). Sequential treatment greatly reduced phytotoxicity of wastewater and showed the highest germination percentage (90%) compared to aerobic (60%), anaerobic (70%) treatments and untreated wastewater (30%). Regression analysis also endorsed these findings (R2 = 0.76–0.95 between seed germination, seedling growth and vigor). MFL technique was adopted to simulate sequential treatment process. The results support higher performance of MFL model to predict TDS, TSS, COD, and BOD based on the physico-chemical water quality parameters of raw wastewater, time of treatment and treatment type variation. Based on these findings, we conclude that the sequential treatment could be a more effective strategy for treatment of pulp and paper industrial wastewater with efficiency to be used for agricultural industry without toxic effects.