in recent years seem to be very stable in all weather conditions, and processing such
dye is more complicated. The methods to treat dye that are in practice these days
seem to be conventional, namely, biological oxidation, adsorption, and coagulation
by iron salts. Sometimes a more effective conventional technique of ozonation has
been used. However, reducing all the effluents from wastewater is a difficult task for
any method. An innovative method of treating the early-stage dye and finishingstage dye separately using a cellulosic reactive azo process was done by Vlyssides
et al. (2000). They reported that electrolytic method gave satisfactory results after
reduction of the organic load and the color of the effluent. At the end, they concluded
that color reduction is of most importance factor for the textile industries. The results
showed that chemical oxygen demand (COD), as well as biochemical oxygen
demand (BOD), were substantially reduced.
A study by Bilinska et al. (2017) adopted the most advanced and innovative
oxidation process to treat highly contaminated wastewater. An investigation was
carried out on a simulated mixture that was prepared by blending the highly reactive
agents of RY145, RR195, and RB221 at specific proportions. A variety of ozonebased advanced oxidation processes (AOPs) was compared with conventional techniques and assessed. Besides, the effect of hydrogen peroxide and UV during the
process has also been investigated. As the mixture was composed of several dyes,
the evaluation was carried out using the UV-Vis spectra technique. The addition of
such coloring agents has turned to the decolorization of wastewater very rapidly. It
was noticed that only 10% of decolorization was left behind after treatment for
10 min. Therefore, AOPs seem to be a promising technique and can readily be used
in such a harsh environment very effectively.
A membrane modification technique with polydopamine (PDA) coating was used
in the infiltration process by Ye et al. (2020) in their study. This modification
technique has gained huge interest among researchers due to its intrinsic adhesion
nature. Tight ultrafiltration membranes having a molecular weight between 1000 and
5000 Da were coated with polyethyleneimine ammonium persulfate. The use of
ammonium persulfate is to oxidize the polydopamine rapidly along the surface of the
substrate through a Schiff base reaction. By depositing such highly oxidizing
polydopamine in ammonium persulfate atmosphere for nearly 1.5 h, a defect-free
polydopamine with membranes of 1700 Da can be expected, which is capable of
desalinating up to 99.95% and yielding 99.2% dye recovery. The results indicated
that membrane modification using polydopamine is a better choice in dye desalination and recovery.
With an idea to find opportunities to reuse the separate streams of wastewater or
composite wastewater from mill, Cinperi et al. (2019) prepared three separate
wastewater streams. Moreover, five different concentrations of water were also
characterized. A pilot-scale study was carried out using membrane bioreactor,
nanofiltration, and reverse osmosis techniques. The addition of coloring agents in
separate streams has resulted in peaks and oscillations depicting the mixing effects.
After the membrane bioreactor test, the content of COD was 70%, while BOD was
74%, with TSS to be 86%, TN estimated to be 28%, and TP to be 43%. As the
combined membrane bioreactor and nanofiltration resulted in 40–99% removal
292
P. Pattnaik and G. S. Dangayach
dye is more complicated. The methods to treat dye that are in practice these days
seem to be conventional, namely, biological oxidation, adsorption, and coagulation
by iron salts. Sometimes a more effective conventional technique of ozonation has
been used. However, reducing all the effluents from wastewater is a difficult task for
any method. An innovative method of treating the early-stage dye and finishingstage dye separately using a cellulosic reactive azo process was done by Vlyssides
et al. (2000). They reported that electrolytic method gave satisfactory results after
reduction of the organic load and the color of the effluent. At the end, they concluded
that color reduction is of most importance factor for the textile industries. The results
showed that chemical oxygen demand (COD), as well as biochemical oxygen
demand (BOD), were substantially reduced.
A study by Bilinska et al. (2017) adopted the most advanced and innovative
oxidation process to treat highly contaminated wastewater. An investigation was
carried out on a simulated mixture that was prepared by blending the highly reactive
agents of RY145, RR195, and RB221 at specific proportions. A variety of ozonebased advanced oxidation processes (AOPs) was compared with conventional techniques and assessed. Besides, the effect of hydrogen peroxide and UV during the
process has also been investigated. As the mixture was composed of several dyes,
the evaluation was carried out using the UV-Vis spectra technique. The addition of
such coloring agents has turned to the decolorization of wastewater very rapidly. It
was noticed that only 10% of decolorization was left behind after treatment for
10 min. Therefore, AOPs seem to be a promising technique and can readily be used
in such a harsh environment very effectively.
A membrane modification technique with polydopamine (PDA) coating was used
in the infiltration process by Ye et al. (2020) in their study. This modification
technique has gained huge interest among researchers due to its intrinsic adhesion
nature. Tight ultrafiltration membranes having a molecular weight between 1000 and
5000 Da were coated with polyethyleneimine ammonium persulfate. The use of
ammonium persulfate is to oxidize the polydopamine rapidly along the surface of the
substrate through a Schiff base reaction. By depositing such highly oxidizing
polydopamine in ammonium persulfate atmosphere for nearly 1.5 h, a defect-free
polydopamine with membranes of 1700 Da can be expected, which is capable of
desalinating up to 99.95% and yielding 99.2% dye recovery. The results indicated
that membrane modification using polydopamine is a better choice in dye desalination and recovery.
With an idea to find opportunities to reuse the separate streams of wastewater or
composite wastewater from mill, Cinperi et al. (2019) prepared three separate
wastewater streams. Moreover, five different concentrations of water were also
characterized. A pilot-scale study was carried out using membrane bioreactor,
nanofiltration, and reverse osmosis techniques. The addition of coloring agents in
separate streams has resulted in peaks and oscillations depicting the mixing effects.
After the membrane bioreactor test, the content of COD was 70%, while BOD was
74%, with TSS to be 86%, TN estimated to be 28%, and TP to be 43%. As the
combined membrane bioreactor and nanofiltration resulted in 40–99% removal
292
P. Pattnaik and G. S. Dangayach