36
A. Geethakarthi
Table 10 Advantages and limitations of biological decolourization technologies [8]
Technologies
Advantages
Limitations
Biodegradation
Economically attractive
Most commonly acceptable
treatment
Slow process, maintenance and
nutrient requirements
Suitable only in favourable
environment
Anaerobic process
Resistant to wide variety of
complex colourants
Biogas produced is used for
steam generation
1. Longer acclimatization phase
Aerobic process
1. Colour removal is
facilitated along with
COD removal
1. Longer detention period and
specific substrate removal
2. Less resistant to recalcitrant
dyes
Single cell (fungal, algal and
bacteria)
Good removal efficiency for
low volumes and
concentrations
Very effective for specific
colourant removal
Culture maintenance is
cost-intensive
Cannot cope up with large
volumes of coloured effluents
and simplicity of design, ease of operation and insensitivity to toxic pollutants. An
ideal sorbent meets the following criteria:
1. Large internal surface area to interact and admit the molecules to be adsorbed
2. High affinity and capacity for target compounds
3. High regenerative capacity
4. Long ageing period, thereby maintaining adsorptive capacity through enhanced
recycling
5. Possess tolerance for a wide range of effluent parameters
6. Mechanically strong enough to withstand the bulk handling and vibration.
2.1 Adsorption Mechanism
The optimization and design of an adsorption system can only be understood by
adsorption mechanism. The effective activation and regeneration of the adsorbents
can be achieved only by proper adsorption mechanism. The mechanism involved in
colour or ionic removal processes is through the following 3 steps:
1. Diffusion of the adsorbate molecules through the solution onto surface of the
adsorbents
2. Adsorption of adsorbate on the surface of materials through molecular
interactions and
3. Diffusion of molecules to be adsorbed from the surface into the interior of the
adsorbent materials.
A. Geethakarthi
Table 10 Advantages and limitations of biological decolourization technologies [8]
Technologies
Advantages
Limitations
Biodegradation
Economically attractive
Most commonly acceptable
treatment
Slow process, maintenance and
nutrient requirements
Suitable only in favourable
environment
Anaerobic process
Resistant to wide variety of
complex colourants
Biogas produced is used for
steam generation
1. Longer acclimatization phase
Aerobic process
1. Colour removal is
facilitated along with
COD removal
1. Longer detention period and
specific substrate removal
2. Less resistant to recalcitrant
dyes
Single cell (fungal, algal and
bacteria)
Good removal efficiency for
low volumes and
concentrations
Very effective for specific
colourant removal
Culture maintenance is
cost-intensive
Cannot cope up with large
volumes of coloured effluents
and simplicity of design, ease of operation and insensitivity to toxic pollutants. An
ideal sorbent meets the following criteria:
1. Large internal surface area to interact and admit the molecules to be adsorbed
2. High affinity and capacity for target compounds
3. High regenerative capacity
4. Long ageing period, thereby maintaining adsorptive capacity through enhanced
recycling
5. Possess tolerance for a wide range of effluent parameters
6. Mechanically strong enough to withstand the bulk handling and vibration.
2.1 Adsorption Mechanism
The optimization and design of an adsorption system can only be understood by
adsorption mechanism. The effective activation and regeneration of the adsorbents
can be achieved only by proper adsorption mechanism. The mechanism involved in
colour or ionic removal processes is through the following 3 steps:
1. Diffusion of the adsorbate molecules through the solution onto surface of the
adsorbents
2. Adsorption of adsorbate on the surface of materials through molecular
interactions and
3. Diffusion of molecules to be adsorbed from the surface into the interior of the
adsorbent materials.