384
D. Raha et al.
1 Introduction
The milk production unit and dairy plant emanate high volume of wastewater
containing formidable amount of organics and nitrogenous substances (Tripathi and
Upadhyay 2003). It is reported that dairy industry releases on an average of 0.2–10 L
of effluent per litre of milk processing (Vourch et al. 2008). Wastewater emanates
such plants contain high level of suspended solids, BOD, COD, nitrogen, oil, fat,
grease contents along with varied pH levels due to different cleansing strategies,
which necessitates a special treatment to minimize the environmental problems.
A high degree of wastewater treatment would be accomplished before its discharge
in water environment to maintain ecological harness. Biological treatment is one of
the alternative options for treatment of above wastewater because of high soluble
BOD, high COD concentration and proven reliable processing technology. Furthermore, resulting end products emerge from this process are innocuous in nature.
Biological treatment methods for treating dairy wastewater are advocated by Kargi
and Dincer (1997) containing multi-substrates such as COD, N and P. The aim of the
study was to perform a laboratory scale batch experiment to treat dairy plant effluent
emphasis as COD and nitrogen removal to estimate kinetic constant using Monod’s
equation for designing reactor for a real-life application.
2 Materials and Methods
2.1 Seed Acclimatization
A glass cylinder of 1000 mL capacity was taken as an acclimatization unit. A nonacclimatized seed from nearby small-scale dairy industry was collected and mixed
with waste samples and necessary air was supplied continuously with the help of
small compressor unit. Seed acclimatization phase was continued for 2 months and
considered to be complete when a steady performance was noted for a consistent
COD removal and growth of biomass.
For acclimatization of nitrifiers, a separate synthetic solution was prepared in
a cylinder of 1.0 L capacity, in which NH 4 Cl and (NH 4 ) 2 SO 4 of concentration of
0.10 g/L and 0.05 g/L, respectively, were added as nitrogen source to stimulate the
appropriate environmental conditions. Necessary aeration was accomplished through
a small compressor unit. pH within the cylinder was kept in the range of 7.5–8.0 by
the addition of necessary doses of 0.1 N sodium bicarbonate (NaHCO 3 ) solution.
The denitrifying sludge was collected from a anaerobic digester unit. A separate
denitrifying unit was employed, i.e. an aspirator bottle, kept on a magnetic stirrer, for
mixing well in absence of oxygen. The seed was acclimatized by adding potassium
nitrate (KNO 3 ) having NO 3
− –N concentration of 10–30 mg/L for a time period of
D. Raha et al.
1 Introduction
The milk production unit and dairy plant emanate high volume of wastewater
containing formidable amount of organics and nitrogenous substances (Tripathi and
Upadhyay 2003). It is reported that dairy industry releases on an average of 0.2–10 L
of effluent per litre of milk processing (Vourch et al. 2008). Wastewater emanates
such plants contain high level of suspended solids, BOD, COD, nitrogen, oil, fat,
grease contents along with varied pH levels due to different cleansing strategies,
which necessitates a special treatment to minimize the environmental problems.
A high degree of wastewater treatment would be accomplished before its discharge
in water environment to maintain ecological harness. Biological treatment is one of
the alternative options for treatment of above wastewater because of high soluble
BOD, high COD concentration and proven reliable processing technology. Furthermore, resulting end products emerge from this process are innocuous in nature.
Biological treatment methods for treating dairy wastewater are advocated by Kargi
and Dincer (1997) containing multi-substrates such as COD, N and P. The aim of the
study was to perform a laboratory scale batch experiment to treat dairy plant effluent
emphasis as COD and nitrogen removal to estimate kinetic constant using Monod’s
equation for designing reactor for a real-life application.
2 Materials and Methods
2.1 Seed Acclimatization
A glass cylinder of 1000 mL capacity was taken as an acclimatization unit. A nonacclimatized seed from nearby small-scale dairy industry was collected and mixed
with waste samples and necessary air was supplied continuously with the help of
small compressor unit. Seed acclimatization phase was continued for 2 months and
considered to be complete when a steady performance was noted for a consistent
COD removal and growth of biomass.
For acclimatization of nitrifiers, a separate synthetic solution was prepared in
a cylinder of 1.0 L capacity, in which NH 4 Cl and (NH 4 ) 2 SO 4 of concentration of
0.10 g/L and 0.05 g/L, respectively, were added as nitrogen source to stimulate the
appropriate environmental conditions. Necessary aeration was accomplished through
a small compressor unit. pH within the cylinder was kept in the range of 7.5–8.0 by
the addition of necessary doses of 0.1 N sodium bicarbonate (NaHCO 3 ) solution.
The denitrifying sludge was collected from a anaerobic digester unit. A separate
denitrifying unit was employed, i.e. an aspirator bottle, kept on a magnetic stirrer, for
mixing well in absence of oxygen. The seed was acclimatized by adding potassium
nitrate (KNO 3 ) having NO 3
− –N concentration of 10–30 mg/L for a time period of