Environmental Biotechnology
Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 9 No. 4, Issue of July 15, 2006
© 2006 by Pontificia Universidad Católica de Valparaíso -- Chile Received May 26, 2005 / Accepted November 21, 2006
DOI: 10.2225/vol9-issue4-fulltext-11  
RESEARCH ARTICLE

Effect of sulphate concentration and sulphide desorption on the combined removal of organic matter and sulphate from wastewaters using expanded granular sludge bed (EGSB) reactors 

Freddy Valdés
 Departamento de Ingeniería Química
Facultad de Ingeniería, Ciencias y Administración
Universidad de La Frontera
Casilla 54-D, Temuco, Chile
Tel: 56 45 325472
Fax: 56 45 325053 

Edmundo Muñoz
 Departamento de Ingeniería Química
Facultad de Ingeniería, Ciencias y Administración
Universidad de La Frontera
Casilla 54-D, Temuco, Chile
Tel: 56 45 325472
Fax: 56 45 325053

Rolando Chamy
 Escuela de Ingeniería Bioquímica
Facultad de Ingeniería
Pontificia Universidad Católica de Valparaíso
General Cruz 34
Valparaíso, Chile
Tel: 56 32 273651
Fax: 56 32 273803
E-mail: rchamy@ucv.cl

Gonzalo Ruiz
 Escuela de Ingeniería Bioquímica
Facultad de Ingeniería
Pontificia Universidad Católica de Valparaíso
General Cruz 34
Valparaíso, Chile
Tel: 56 32 273651
Fax: 56 32 273803 

Christian Vergara
 Departamento de Ingeniería Química
Facultad de Ingeniería, Ciencias y Administración
Universidad de La Frontera
Casilla 54-D, Temuco, Chile
Tel: 56 45 325472
Fax: 56 45 325053 

David Jeison*
 Departamento de Ingeniería Química
Facultad de Ingeniería, Ciencias y Administración
Universidad de La Frontera
Casilla 54-D, Temuco, Chile
Tel: 56 45 325472
Fax: 56 45 325053
E-mail: djeison@ufro.cl

*Corresponding author

Financial support: Research Project FONDECYT 1020201.

Keywords: anaerobic digestion, EGSB, sulphate reduction, sulphide.

Abbreviations:

CH+: H+ concentration
CH2S:H2S concentration (liquid phase)
CHS-: HS- concentration
COD: chemical oxygen demand
CTS: total sulphide concentration
CTS-C: total sulphide concentration in column effluent
CTS-EGSB: total sulphide concentration in EGSB effluent
EGSB: Expanded Granular sludge Bed
FEGSB: inlet liquid flow rate of EGSB reactor
FR: recirculation liquid flow
GBiogas: biogas molar gas rate production
GC; molar gas rate in column
H: Henry constant for H2S
Ka: acid/base equilibrium constant for H2S
nS: sulphide volumetric production rate in EGSB reactor
OLR: organic loading rate
SLR: sulphate loading rates
TS: total sulphide
VEGSB: volume of EGSB reactor
yH2S: molar fraction of sulphide (gas phase)
yH2S-Biogas: molar fraction of sulphide in the biogas
yH2S-C: molar fraction of sulphide in gas leaving the column
Abstract
Full Text

During the application of anaerobic processes to high sulphate concentration wastewaters, operational problems are expected due to the occurrence of sulphate reduction. Sulphide production reduces effluent quality and may produce inhibition. The application of Expanded Granular Sludge Bed (EGSB) reactors for the combined removal of organic matter and sulphate was studied at different COD/sulphate and 3 values of pH. During the EGSB reactor operation, most of the sulphide remains in the liquid phase reducing effluent quality. The inclusion of a desorption column in the recirculation of the EGSB reactor promotes mass transfer to the gas phase, reducing the sulphide concentration in the liquid phase, significantly decreasing the chemical oxygen demand of the effluent.
 
Supported by UNESCO / MIRCEN network
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