Treatment of source-separated urine by a combination of bipolar electrodialysis and a gas transfer membrane

2006 ◽  
Vol 53 (3) ◽  
pp. 139-146 ◽  
Author(s):  
W. Pronk ◽  
M. Biebow ◽  
M. Boller
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Ammonium Phosphate ◽  
Low Ph ◽  
Bubble Columns ◽  
Gas Transfer ◽  
Additional Mass ◽  
Hydrophobic Membrane ◽  
Bipolar Membranes ◽  
Transfer Unit

Urine contains nutrients which can be applied usefully as a fertiliser in agriculture, but the relatively high pH can lead to ammonia evaporation. Electrodialysis with bipolar membranes was combined with an additional mass transfer unit in order to render a product containing ammonium and phosphate at a low pH. In one case, the additional mass transfer unit consisted of bubble columns placed in acid and basic concentrate streams, connected with a circulating gas phase. In the other case, the unit consisted of a gas-filled (hydrophobic) membrane placed in between the circulating acid and basic concentrate streams. The results showed that ammonia was transferred through the gas phase, but also carbonate, which is present in stored urine originating from the hydrolysis of urea. Although the pH in the product stream decreases initially, it rises above pH 7 at longer operation times. This pH increase can be attributed to a combination of proton compensating effects. The use of ammonia-selective membranes for the transfer into the acid concentrate could provide a solution to generate an ammonium phosphate product at low pH and high recoveries.

Influence of liquid properties on mass transfer coefficients in bubble columns

1988 ◽  
Vol 53 (4) ◽  
pp. 763-770 ◽  
Author(s):  
Kurt Winkler ◽  
František Kaštánek ◽  
Jan Kratochvíl
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Binary Systems ◽  
Bubble Column ◽  
Surface Force ◽  
Interfacial Area ◽  
Bubble Columns ◽  
Transfer Coefficients ◽  
Phase Velocities ◽  
Specific Interfacial Area

The gas phase holdup, the specific interfacial area a, and the liquid-side volumetric mass transfer coefficient kLa have been determined for two selected binary systems water-butanol and butanol-2-ethylhexanol in a short bubble column of 150 mm i.d. at gas phase velocities (air) in the range of uG = (0.31-2.52) . 10-2 m s-1. The kLa-uG dependences show characteristic maxima which only partially can be explained by molecular and surface force interactions, induced by the liquid phase. The main parameter, influencing the kLa-values, is a. At small gas velocities some irregularities in the Sauter diameter d32 and in the values of separated kL are observed.

scholarly journals DESIGN OF A PACKED-BED ABSORPTION COLUMN CONSIDERING FOUR PACKING TYPES AND APPLYING MATLAB

2016 ◽  
Vol 29 (2) ◽  
pp. 83-104 ◽  
Author(s):  
A. Pérez Sánchez ◽  
E. J. Pérez Sánchez ◽  
R. Segura Silva
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Gas Phase ◽  
Phase Transfer ◽  
Packed Bed ◽  
Design Parameters ◽  
Microsoft Excel ◽  
Absorption Column ◽  
Transfer Unit ◽  
Gaseous Stream

In the present work, a packed bed absorption column is designed to recover certain amounts of ethanol contained in a gaseous stream. Four packing types (50-mm metal Hiflow® rings, 50-mm ceramic Pall® rings, 50-mm metal Top Pak® rings and 25-mm metal VSP® rings) are considered in order to select the most appropriate one in terms of column dimensions, pressure drop and mass-transfer results. Several design parameters were determined including column diameter (D), packing height (Z), overall mass-transfer coefficient (Km) and gas pressure drop (P/Z), as well as the overall number of gas-phase transfer units (NtOG), overall height of a gas-phase transfer unit (HtOG) and the effective surface area of packing (ah). The most adequate packing to use for this absorption system constitutes the 25-mm metal VSP® rings, since it provided the greatest values of Km (0.325 kmol/m3.s), and ah (169.57 m-1), as well as the lowest values of both Z (0.6 m) and HtOG (0.145 m), meaning that it will supply the higher mass-transfer conditions with the lowest column dimensions. The influence of both gas mixture (QG) and solvent (mL) feed flowrates on D, Z, Km, P/Z, NtOG and HtOG was also evaluated for the four packing considered. The design methodology was solved using computing software MATLAB® version 7.8.0.347 (R2009a) (Math Works, 2009), and also Microsoft Excel®.D

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

Analysis of Heat and Mass Transfer Between a Desiccant-Air System in a Packed Tower

1987 ◽  
Vol 109 (2) ◽  
pp. 89-93 ◽  
Author(s):  
P. Gandhidasan ◽  
M. Rifat Ullah ◽  
C. F. Kettleborough
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Heat And Mass Transfer ◽  
Packing Material ◽  
Mass Transfer Resistance ◽  
Liquid Desiccant ◽  
Governing Equations ◽  
Packed Tower ◽  
Transfer Resistance ◽  
Steady State Model

Heat and mass transfer analysis between a desiccant-air contact system in a packed tower has been studied in application to air dehumidification employing liquid desiccant, namely calcium chloride. Ceramic 2 in. Raschig rings are used as the packing material. To predict the tower performance, a steady-state model which considers the heat and mass transfer resistances of the gas phase and the mass transfer resistance of the liquid phase is developed. The governing equations are solved on a digital computer to simulate the performance of the tower. The various parameters such as the effect of liquid concentration and temperature, air temperature and humidity and the rates of flow of air and liquid affecting the tower performance have been discussed.

scholarly journals Effect of fluid properties on mass transfer in the gas phase

AIChE Journal ◽  
1955 ◽  
Vol 1 (1) ◽  
pp. 9-19 ◽  
Author(s):  
E. J. Lynch ◽  
C. R. Wilke
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Fluid Properties

Gas-phase mass-transfer in a disk-column

1959 ◽  
Vol 11 (2) ◽  
pp. 130-137 ◽  
Author(s):  
N.A. Warner
Keyword(s):  
Mass Transfer ◽  
Gas Phase
Sign in / Sign up

Export Citation Format

Share Document