385
3. Tertiary treatment process: The tertiary treatment process is the final removal
stage of conventional treatment process to make the effluent suitable for intended
reuse. In this process, all the pollutants such as suspendeded solids, organic matters, heavy metals, pathogens, which are difficult to remove in secondary treatment process, can be eliminated.
From the last few decades, different technologies have been developed to remove
the different types of toxic dyes from the industrial effluents. Those are categorized
in three groups: a) physical treatment, b) chemical treatment, and c) biological
treatment.
(a) Physical Treatment
Different types of physical processes are applied for the treatment of dyes such
as screening, coagulation, precipitation, adsorption, and membrane filtration.
Among all, adsorption has been found the best process for the removal of dyes due
to its simple design, easy operation, higher efficiency, low costs, and no effect by
toxic substances. Membrane fouling and membrane replacement cost are the major
restrictions for the membrane filtration (Ruan et al. 2019).
(b) Chemical Treatment
The chemical treatment methods include coagulation-flocculation, oxidation,
ozonation, Fenton oxidation, photocatalytic oxidation, irradiation, ion exchange,
and electrochemical treatment. These chemical methods are very efficient for dye
removal but excessive chemical use causes the difficulty of sludge disposal, very
high cost, and also electrical energy is required for these techniques (Ruan
et al. 2019).
(c) Biological Method
The biological treatment methods include aerobic treatment, anaerobic treatment, and anaerobic-aerobic treatment where the organic pollutants are converted
into harmless and stable substances. Aerobic treatment involves activated sludge,
aerobic digestion, trickling filtration, lagoons, ponds, oxidation, and anaerobic
treatment involves anaerobic digestion, lagoons, and septic tanks. The conventional
treatment methods for dye removal based on physicochemical treatment and biological treatment from wastewater are given in Fig.15.3.
15.3.1 Physicochemical Treatment
Coagulation and flocculation process is an efficient, simple, and cost-effective process widely used for effluent treatment, drinking water treatment, and reduction of
chemical oxygen demand (Ruan et al. 2019). The process is performed by destabilization of charged particles dispersed in water by reducing the charge of the surface
and the formation of large particle by accumulation. Coagulants mainly used in this
15 Remediation of Dyes from Industrial Wastewater Using Low-Cost Adsorbents
3. Tertiary treatment process: The tertiary treatment process is the final removal
stage of conventional treatment process to make the effluent suitable for intended
reuse. In this process, all the pollutants such as suspendeded solids, organic matters, heavy metals, pathogens, which are difficult to remove in secondary treatment process, can be eliminated.
From the last few decades, different technologies have been developed to remove
the different types of toxic dyes from the industrial effluents. Those are categorized
in three groups: a) physical treatment, b) chemical treatment, and c) biological
treatment.
(a) Physical Treatment
Different types of physical processes are applied for the treatment of dyes such
as screening, coagulation, precipitation, adsorption, and membrane filtration.
Among all, adsorption has been found the best process for the removal of dyes due
to its simple design, easy operation, higher efficiency, low costs, and no effect by
toxic substances. Membrane fouling and membrane replacement cost are the major
restrictions for the membrane filtration (Ruan et al. 2019).
(b) Chemical Treatment
The chemical treatment methods include coagulation-flocculation, oxidation,
ozonation, Fenton oxidation, photocatalytic oxidation, irradiation, ion exchange,
and electrochemical treatment. These chemical methods are very efficient for dye
removal but excessive chemical use causes the difficulty of sludge disposal, very
high cost, and also electrical energy is required for these techniques (Ruan
et al. 2019).
(c) Biological Method
The biological treatment methods include aerobic treatment, anaerobic treatment, and anaerobic-aerobic treatment where the organic pollutants are converted
into harmless and stable substances. Aerobic treatment involves activated sludge,
aerobic digestion, trickling filtration, lagoons, ponds, oxidation, and anaerobic
treatment involves anaerobic digestion, lagoons, and septic tanks. The conventional
treatment methods for dye removal based on physicochemical treatment and biological treatment from wastewater are given in Fig.15.3.
15.3.1 Physicochemical Treatment
Coagulation and flocculation process is an efficient, simple, and cost-effective process widely used for effluent treatment, drinking water treatment, and reduction of
chemical oxygen demand (Ruan et al. 2019). The process is performed by destabilization of charged particles dispersed in water by reducing the charge of the surface
and the formation of large particle by accumulation. Coagulants mainly used in this
15 Remediation of Dyes from Industrial Wastewater Using Low-Cost Adsorbents