13.9 Merit and Demerits of Coagulation/Flocculation (C/F)
in Dye Wastewater Treatment
The significant popularity of coagulation/flocculation process in dye wastewater
treatment is because of its simple design and operational procedure. Apart from
this, the process has the following advantages that make it an extensively used
method for dye wastewater treatment.
13.9.1 Merits of the Coagulation/Flocculation Process
1. Provoke the destabilization of colloidal and dissolved particles. The coagulation
process with the help of coagulant initiates the destabilization of colloidal particles which are difficult to settle under the effect of gravity (Baker 1948). Thus,
this process fastens the natural settling of colloidal particles using coagulant/
flocculants.
2. Reduces the turbidity of the water. The coagulation/flocculation process comprises of primary treatment that eliminates 90% of settleable particles, along with
other dissolved and suspended particles (Peavy et al. 1985). As these particles
sink down, the turbidity and dissolved organic compounds get significantly
reduced.
3. Reduces the oxygen demand of water. The process substantially reduces the
colloidal particles and dissolved organic compounds, thereby significantly
curtailing the BOD and some COD of the wastewater.
4. Enhances the functioning of secondary and tertiary treatment units. This process
carries a significant amount of organic and inorganic pollutants along with the
settled colloidal particles and hence reduces the over-functioning of other secondary treatment by reducing maximum pollutants initially.
5. Curtail the total treatment cost. The coagulation/flocculation process is the costeffective, simple and potential treatment process for decolourization of dyes
(Chen et al. 2010). Hence this process reduces the total cost of treatment as
compared to other advanced treatment methods used alone.
6. Prevent the formation of harmful by-products. Other advance oxidation processes
such as photocatalytic oxidation, ozonation, etc. are used for the treatment of dye
wastewater from toxic by-products that seem to be potential carcinogens. But the
coagulation/flocculation process has advantage over them, as this process
removes the colour but not by partial decomposition (Golob et al. 2005).
The efficiency of the primary treatment solely depends on the performance of other
secondary treatment methods. Being the part of primary treatment, the coagulation/
flocculation process, besides having some advantages, faces some flaws also which
are described as follows.
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S. Sonal and B. K. Mishra
in Dye Wastewater Treatment
The significant popularity of coagulation/flocculation process in dye wastewater
treatment is because of its simple design and operational procedure. Apart from
this, the process has the following advantages that make it an extensively used
method for dye wastewater treatment.
13.9.1 Merits of the Coagulation/Flocculation Process
1. Provoke the destabilization of colloidal and dissolved particles. The coagulation
process with the help of coagulant initiates the destabilization of colloidal particles which are difficult to settle under the effect of gravity (Baker 1948). Thus,
this process fastens the natural settling of colloidal particles using coagulant/
flocculants.
2. Reduces the turbidity of the water. The coagulation/flocculation process comprises of primary treatment that eliminates 90% of settleable particles, along with
other dissolved and suspended particles (Peavy et al. 1985). As these particles
sink down, the turbidity and dissolved organic compounds get significantly
reduced.
3. Reduces the oxygen demand of water. The process substantially reduces the
colloidal particles and dissolved organic compounds, thereby significantly
curtailing the BOD and some COD of the wastewater.
4. Enhances the functioning of secondary and tertiary treatment units. This process
carries a significant amount of organic and inorganic pollutants along with the
settled colloidal particles and hence reduces the over-functioning of other secondary treatment by reducing maximum pollutants initially.
5. Curtail the total treatment cost. The coagulation/flocculation process is the costeffective, simple and potential treatment process for decolourization of dyes
(Chen et al. 2010). Hence this process reduces the total cost of treatment as
compared to other advanced treatment methods used alone.
6. Prevent the formation of harmful by-products. Other advance oxidation processes
such as photocatalytic oxidation, ozonation, etc. are used for the treatment of dye
wastewater from toxic by-products that seem to be potential carcinogens. But the
coagulation/flocculation process has advantage over them, as this process
removes the colour but not by partial decomposition (Golob et al. 2005).
The efficiency of the primary treatment solely depends on the performance of other
secondary treatment methods. Being the part of primary treatment, the coagulation/
flocculation process, besides having some advantages, faces some flaws also which
are described as follows.
324
S. Sonal and B. K. Mishra