Influence of the fetch parameter on results from empirical correlations for estimating odorous emissions at passive liquid surfaces

2016 ◽  
Vol 74 (10) ◽  
pp. 2384-2391 ◽  
Author(s):  
Ademir A. Prata ◽  
Milena J. Calvo ◽  
Gaetano Boncardo ◽  
Eric C. Sivret ◽  
Jane M. Santos ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Model Compound ◽  
Emission Rate ◽  
Wastewater Treatment Plants ◽  
Effective Diameter ◽  
Empirical Correlations ◽  
Film Mass Transfer ◽  
Liquid Surfaces

Passive liquid surfaces in wastewater treatment plants may be potential sources of odorous emissions. This study investigates the occurrence and significance of deviations that may originate from the use of the effective diameter as fetch parameter in the empirical correlations utilised by the WATER9 model to estimate odorous emissions at passive liquid surfaces. A sensitivity analysis was performed using benzene as a model compound and considering representative conditions of wind speed and wind alignment. The gas-film mass transfer coefficient (kG) was found relatively in sensitive to the choice of the fetch parameter, deviating less than 15% for aspect rations up to 15. The calculation of the liquid-film mass transfer coefficient (kL) was much more sensitive (positive extreme of 126.98% and negative extreme of −54.80%), partially because of the use of different equations for different fetch-to-depth ratios. For more volatile compounds, such as benzene, these discrepancies will be significantly manifested in the estimated emission rate. When appropriate, the use of the actual fetch instead of the effective diameter is recommended.

Sensitivity analysis of the WATER9 model: emissions of odorous compounds from passive liquid surfaces present in wastewater treatment plants

2018 ◽  
Vol 2017 (3) ◽  
pp. 903-912
Author(s):  
Milena J. Calvo ◽  
Ademir A. Prata ◽  
Leonardo Hoinaski ◽  
Jane M. Santos ◽  
Richard M. Stuetz
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Liquid Phase ◽  
Wind Speed ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Wastewater Treatment Plants ◽  
Effective Diameter ◽  
Odorous Compounds ◽  
Liquid Surfaces

Abstract Empirical mathematical models have been frequently used to estimate emissions and to act in the prevention of possible impacts from odorous compounds. Based on the regulatory WATER9 model, the present study had the aim to evaluate the deviations originating from the simplification of using the effective diameter (in contrast to the conceptually appropriate use of the linear physical fetch) as fetch parameter in the calculation of the global mass transfer coefficient at passive liquid surfaces at wastewater treatment plants (WWTPs). The present analysis incorporated the influence of different values of wind velocity, molecular diffusivity and Henry's Law constant. The analyses for the calculation of the mass transfer coefficients were developed for 1,000 wind speeds, chosen using the Monte Carlo method, three WWTPs and three compounds of environmental relevance, spanning different behaviour regarding their volatilisation. The wind speed had a direct influence on the deviations for all types of compounds analysed. However, this parameter was found to be more representative for the compounds whose volatilisation is limited by conditions in the liquid phase. Furthermore, the deviations for the calculation of the mass transfer coefficient arising from the use of the effective diameter as fetch parameter were significantly larger for liquid phase-dominated compounds, compared to gas phase-dominated compounds. Comparison against available experimental data confirm that the use of the effective diameter as the fetch parameter makes the model predictions further depart from the experimental values. The present analysis shows that, for a varied range of wind speed and WWTP configurations, the use of the actual physical fetch shall be preferred over the use of the effective diameter in emission models for WWTPs, so as to avoid the introduction of potentially large systematic deviations.

Experimental determination of fluid-film mass transfer coefficient from adsorption uptake curve

2011 ◽  
Vol 173 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Junpei Fujiki ◽  
Tatsuru Shinomiya ◽  
Takashi Kawakita ◽  
Seiji Ishibashi ◽  
Eiji Furuya
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Experimental Determination ◽  
Fluid Film ◽  
Uptake Curve ◽  
Film Mass Transfer

scholarly journals Hydrodynamics and mass transfer in Kühni extraction columns

2021 ◽  
pp. 14-14
Author(s):  
Milan Sovilj ◽  
Momcilo Spasojevic
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Dispersed Phase ◽  
Drop Diameter ◽  
Phase System ◽  
Rotor Speed ◽  
Empirical Correlations ◽  
Dimensionless Numbers ◽  
Transfer Direction

This work provides a review of hydrodynamic characteristics and mass transfer in the K?hni extraction columns. The experiments, as reported in the literature, were performed in the presence and absence of mass transfer. The results showed that the Sauter mean drop diameter was strongly affected by the rotor speed and interfacial tension, whereas the effects of the dispersed and continuous velocities were negligible. Empirical correlations for the Sauter mean drop diameter, taken from the literature, were discussed. It was experimentally determined that the dispersed-phase holdup depended to a great extent on the rotor speed, mass transfer direction between the phases, physical characteristics of fluids in the liquid-liquid system, and the dispersed-phase flowrate whereas it increased with the increase in mixing in the two-phase system and the ratio of phase flowrates. On the other hand, it has been shown that the mass transfer rate increases with increasing the level of back mixing. It was found that the mass transfer coefficient depends on the rotor speed and the direction of mass transfer between the phases. At the same time, it has been shown that the mass transfer coefficient depends relatively little on the phase flowrates. An empirical correlation was proposed for prediction of the overall mass transfer coefficient based on dimensionless numbers. Also, novel empirical correlations for prediction of the Sherwood number in the continuous phase were presented based on the dispersed-phase holdup, Reynolds number, and mass transfer direction between the phases. Empirical correlations based on dimensionless numbers can be considered as a useful tool for the design of the K?hni columns.

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