Environmental Engineering Reference
In-Depth Information
UASBR: An Effective Wastewater Treatment
Option to Curb Greenhouse Gas Emissions
Rajesh Singh and C.K. Jain
Anaerobic digestion is used for treating high strength organic wastewater. Since late
seventies, anaerobic digestion has experienced an outstanding growth in research
and full scale application, particularly for the treatment of food and beverage indus-
try effluent and to a lesser extent for municipal wastewater (Hulshoff-Pol et al.
1998 ; Yu et al. 2004 ; Fountoulakis et al. 2004 ; Filik-Iscen et al. 2007 ). Anaerobic
digestion is a complex, natural, and multi-stage process in which organic com-
pounds are degraded through a variety of intermediates into methane and carbon
dioxide, by the activity of a consortium of micro organisms. Interdependence of the
bacteria is a key factor in the anaerobic digestion process (Parawira et al. 2005 ) and
the deciding factor for quality of treated effluent as well as gas generation.
The upflow anaerobic sludge blanket reactor (UASBR) is a reactor of upflow
where the organic material on its way through the covering of sludge composed of
a large population of anaerobic bacteria begins its biodegradation. The reactor is
composed of three essential parts: a zone of digestion, a zone of sedimentation,
and a separator of gas-solids-liquids. These are integrated into one column where
the primary sedimentation process, the bio-digestion of the sludge and the sec-
ondary sedimentation is done simultaneously as a primary and secondary treat-
ment of residual waters, achieving efficiency in the removal of organic material
up to 85 % (Sponza 2001 ). Anaerobic digestion treatment is one of the technolo-
gies being considered to provide a solution to the treatment of high strength
organic wastewater and maximum amount of biodegradable fraction can be con-
verted into useful energy end product in the form of biogas and fertilizer in the
form of digestate (Fernandez et al. 2001 ; Saravanan et al. 2004 ; Song et al. 2004 ).
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