Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal weblink: http://www.jett.dormaj.com  
Thermal Catalytic Treatment (Thermolysis): An  
Effective Process for the Removal of COD and  
Color from Industrial Wastewater  
1
2*  
1
3*  
Mohit Nigam , Sunil Rajoriya , Shraddha Rani Singh , Pradeep Kumar  
1
Raja Balwant Singh Engineering Technical Campus, Agra-283105, India  
2
Meerut Institute of Engineering and Technology, Meerut-250005, India  
3
Indian Institute of Technology (BHU), Varanasi-221005, India  
Received: 03/02/2020  
Accepted: 13/04/2020  
Published: 20/05/2020  
Abstract  
Nowadays, water pollution control is one of the global concern areas of scientific research. To meet stringent regulating measures  
set by various regulatory authorities for effluent discharge, it is a challenging task for various industries. Various processes such as  
adsorption, biological process, thermal catalytic, membrane technology, electrochemical etc. are reported for the treatment of industrial  
wastewater. Amongst all the above processes, thermal catalytic process has appeared as an advance process for the treatment of highly  
polluted wastewater originating from various industries. In this paper, mechanism of thermal catalytic (thermolysis) process towards the  
pollutant removal has been discussed. This paper provides information about the recent research on thermal catalytic process for the  
treatment of synthetic and real industrial wastewater. In addition to this, a case study on the treatment of tannery wastewater using  
thermolysis process has also been investigated. The obtained results showed that maximum 65.25% COD and 72.65% color were reduced  
3
using copper sulphate salt with catalyst mass loading of 2 kg/m at pH of 4.  
Keywords: Chemical oxygen demand, Color, Wastewater treatment, Tannery wastewater, Thermal catalytic process  
Introduction1  
catalytic process has gained attention for the treatment of  
1
wastewater discharge from different industries. This novel  
process not only creates the desirable transformation but also  
decreases the total processing cost and has been found to be  
more energy efficient in comparison to many other  
conventional techniques. Thermal catalytic treatment offers  
immense potential for the removal of hardly degradable organic  
pollutant from various industrial effluents (17). Thermal  
catalytic process is an attractive destruction process for the  
treatment of wastewater in which organic and/or inorganic  
substances in aqueous/synthetic solutions gets decomposed and  
form precipitate at moderate or an elevated temperatures and  
self (autogenous) pressure in the absence of air/oxygen with or  
without metal salt catalysts like copper sulphate, copper oxide,  
magnesium oxide, ferric chloride etc. (18, 19). Due to its ease  
in operation, relatively simple equipment design, less  
maintenance and low energy consumption, thermal catalytic  
process can be applied almost all types of waste water. The  
main advantages and disadvantages of thermal catalytic process  
are given in Table 1. This process has been successfully applied  
in different type of industries such as pulp and paper mills (20),  
textile (21-22), alcohol distillery (17-18,23) waste water,  
Petrochemical wastewater (19), sugar industry waste water  
Water is one of the most precious compounds of nature for  
living life on earth. All living organism must have water in  
order to survive. There would be no life on earth without water.  
It covers more than 71% of the earth surface, whereas less than  
1
% of water is for drinking purpose as per international  
st  
standards. Thus, major global challenge for the 21 century to  
have drinkable water (1, 2). Human health is affected by water  
quality typically due to the presence of contaminants in  
drinking water from highly polluted wastewater. With Strictest  
regulation standards set by different regulatory authorities and  
increasing environmental awareness industries faces  
challenges, it requires appropriate waste water treatment  
technologies (3-4). Several industries such as food processing,  
textiles, distilleries, pulp and paper industries, tanneries and  
many other industries are continuously polluting aquatic  
medium in numerous different ways, either discharge directly  
and/or from the treatment plants of wastewater that do not  
fulfill their obligation; as they contains hardly degradable  
organics substances. Traditional biological treatment methods  
are incapable to treat such larger complex compounds (5, 6). In  
the past years, several researchers have studied on the various  
treatment technologies such as electrochemical methods (7-9),  
Adsorption (10, 11), biological process (12), membrane  
processes (13), Advance oxidation process (14) and  
combination of biological and advance oxidation process (15,  
(
24). Further thermal catalytic treatment process may be used  
as a pre-treatment, post-treatment, or even as the main  
treatment of wastewater because of versatility of the treatment  
process (25).  
1
6) for the treatment of wastewater. In the recent years, thermal  
Corresponding author: (a) Sunil Rajoriya, Meerut Institute of Engineering and Technology, Meerut-250005, India. E-mail:  
sunilrajoriya@gmail.com; and (b) Pradeep Kumar, Indian Institute of Technology (BHU), Varanasi-221005, India. Email:  
pkumar.che@iitbhu.ac.in.  
8
18  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
Table 1: Advantages and disadvantages of thermal catalytic treatment process  
Dis-advantages  
1. Need of cleaning of the reactor wall at Periodic  
S.No.  
Advantages  
1
.
.
Simple equipment required, low maintenance, easy to  
operate.  
interval since charred/solid residue gets  
attached to reactor wall.  
2
Efficient for reduction in the COD, color, odor, TDS etc.  
Less sludge generated.  
2. Requirement of acidic resistant reactor since  
the process is generally effective under acidic  
conditions.  
3
4
.
.
3. Required physicochemical monitoring of the  
effluent.  
Residue generated after thermolysis process has good  
calorific value.  
5
6
7
.
.
.
Operating cost is low since no nutrient and air are required.  
Small space required for the treatment.  
Good sludge settling and easy dewatering due to presence  
of Metallic oxides/hydroxides.  
It may be economical and a better supplement to the  
biological and oxidation processes. In this process, organic  
substrate precipitates in the form of solid, can be used as a fuel  
and the ash obtained may be mixed with organic manure for use  
in agriculture/horticulture. The major objective of the present  
study is to provide the detailed information about the recent  
research on the thermal catalytic process towards the treatment  
of industrial wastewater. The mechanism of thermal catalytic  
process has also been discussed. A case study on the treatment  
of tannery wastewater has also been studied in order to check  
the efficiency of the thermal catalytic process.  
are broken down thermally and chemically and undergo  
complexation. Finally, it transforms into insoluble  
particles/molecules which settle down in the reactor. These  
insoluble particles become precipitate in terms of COD and  
color removal. Additionally, larger complex compounds are  
broken down into the smaller soluble compounds. Due to the  
development of insoluble precipitates, substantial reduction in  
terms of COD and color from wastewater takes place (26, 24,  
27). The steps in the mechanism of thermolysis process have  
been shown in Fig. 1. Thermal catalytic reaction in the absence  
of catalyst can be represented as:  
H2Oheat  
Complexorganiccompounds   Solid residuelower molecular weight organics  
2
Mechanism of thermal catalytic (thermolysis)  
process  
Thermal catalytic reaction in the presence of catalyst can be  
written as:  
In thermolysis process, dual mechanisms occur  
simultaneously. The wastewater is subjected to heat in the  
presence of metal based catalyst. At the initial stage, the both  
simple and complex organic compounds present in wastewater  
CatalystH2Oheat  
Complexorganiccompounds Solid residuelower molecular weight organics  
+∆ Thermal Energy  
Metal  
based  
+
catalyst  
(Room temp. to moderate  
temp. up to 95 C)  
0
Disintegration of organic matter  
Organic Compounds  
+
Other Contaminants  
Entrapment /  
Aggregation /  
Complexation  
Solid residue has good micro  
nutrient can be used as a fertilizer  
also has good calorific value can  
be used as a fuel  
Precipitation of organic matter in terms  
of COD/Color reduction  
Figure 1: Mechanism of thermal catalytic process  
8
19  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
Table 2: An Overview of thermolysis process towards the treatment of industrial wastewater in recent years  
Initial  
characteristics  
of wastewater  
Type of  
catalyst  
used  
Optimum  
process  
parameters  
Type of  
wastewater  
Range of  
Parameters  
Important  
References  
outcomes  
S. No.  
COD=108  
3
Alcohol  
distillery  
wastewater  
kg/m , BOD=50  
pH = 1 to 12,  
temp. = 160 to  
250°C  
pH=1,  
Temp.=250 C t  
2 h  
COD reduction=  
Lele et al.  
3
o
1
kg/m , pH=4.5,  
Nil  
Nil  
R
=
59% at pH 1  
(31)  
color=dark  
brown  
(temp. 230°C)  
Distillery  
COD reduction  
=40%, color  
reduction = 30%  
wastewater  
after biogas  
generation  
COD= 35000  
mg/L  
Temperature  
=150°C t  
Dhale et al.  
(33)  
o
2
3
Temp=150 C  
R
= 0.6 h  
pH= 5, C  
kg/m for COD,  
w
=5  
pH=5 to 10.5,  
Cw=1-8kg/m  
COD  
reduction=63.3%  
Color  
3
3
Pulp and  
paper mill  
waste water  
COD=7 kg/m  
Color=dark  
3
CuSO  
4
,CuO,  
Garg et al.  
(20)  
3
C =2 kg./m for  
w
activated carbon Temp.  
brown pH=10.8  
Color, CuSO  
4
catalyst  
o
range=20-95 C  
removal=92.5%  
COD= 34000  
mg/dm ,  
Bio-digester  
effluent from  
alcohol  
distillery  
plant  
Temp. =100-  
3
o
140 C Cw=2 to  
pH=1,  
Temp.=140 C,  
COD reduction  
=70%, BOD  
reduction=83%  
BOD=6300  
Chaudhari et  
al. (18)  
3
o
4
5
CuO  
5kg/m ,  
3
mg/dm ,pH =  
3
Pressure  
range=1-9 bar  
C
w
=3kg/m  
7
.8, color =  
blackish brown  
COD=2884  
pH=2-12  
Temp.=  
atmospheric  
temp. to 95 C  
Catalyst  
2
CuSO4.5H O,  
mg/L BOD3days  
pH=4, C  
w
=4  
kg/m , Temp. =  
95°C t =4 h,  
CuSO  
COD  
reduction=71.6%,  
Color  
CuO, ZnO,  
FeSO4.7H O,  
o
3
Desizing  
wastewater  
at 20 C=3275  
Kumar et al.  
(21)  
2
o
mg/L  
Color=520(PCU  
)
R
2 4 2  
Al (SO )3.16H  
4
removal=87.2%  
O
3
dose=1-8 kg/m  
COD  
reduction=77.9%,  
Color  
reduction=92.85%  
,
Composite  
wastewater of  
a cotton  
COD=1960  
mg/L,  
Color=2250  
(PCU), pH= 7  
pH=2 to 12  
CuSO  
4
, FeSO  
4
,
C
w
=1 to 12  
pH=12 C  
w
= 6  
Kumar et al.  
(22)  
6
7
FeCl , CuO,  
3
3
3
, R  
t
kg/m Temp.  
kg/m  
=4 h  
ZnO and PAC  
o
textile mill  
range =60-95 C  
COD=2884  
mg/L  
BOD3days=3275  
mg/L  
Color=520(PCU  
)
COD  
reduction=88%  
Color  
Commercial  
alum, FeCl ,  
3
FeSO4, PAC  
Desizing  
wastewater  
pH=2-12  
Cw=1-7 kg/m  
pH=4, C  
kg/m ,  
w
=4  
Kumar et al.  
(44)  
3
3
reduction=96%.  
COD = 108,400  
mg/L, BOD =  
48,000 mg/L,  
Color =  
Blackish brown,  
pH = 4.0  
pH=1-10,  
pH=2,  
Alcohol  
wastewater  
Temp. range=  
COD  
removal=60%,  
Chaudhari et  
al. (17)  
o
8
CuO  
Temp.=140 ,  
o
100-140 C, Cw  
3
w
C =3 kg/m  
3
= 2-5 kg/m  
(i)DWW  
COD=108400  
mg/L,  
BOD=48000  
mg/L, Color =  
Blackish  
Brown, pH = 4  
(ii)BDE  
COD=34000  
mg/L,  
BOD=6300  
mg/L, Color =  
Blackish  
(
i) For DWW,  
COD  
Sugarcane  
based alcohol  
industry  
waste water  
DWW and  
BDE  
pH=1-10,  
reduction=47,  
colour reduction  
=68%, (ii) For  
BDE, COD  
reduction=61%,  
color reduction  
pH=less than 2  
CuSO  
CuO, MnO,  
ZnO  
4
.5H  
2
O,  
Temp.=80-  
o
Temp.=100 C  
Chaudhari et  
al. (23)  
o
9
100 C, C  
w
=2-  
=0-12  
3
C
w
=4 kg/m t  
R
=12  
3
5kg/m  
h
,
t
R
h, CuO  
=
78%  
Brown, pH =  
7
.58,  
COD=3320  
Petrochemical mg/L,  
wastewater BOD=963  
mg/L, pH=5.6  
pH=6-10 C  
1-4 kg/m ,  
Temp.  
range=40-90 C  
w
=
pH=7, Cw=3  
3
3
CuSO  
FeCl  
4
, FeSO  
4
,
kg/m , T=50°C  
Time=20 min,  
Catalyst= FeCl  
COD  
reduction=77.2%  
Verma et al.  
(19)  
1
0
3
.
o
3
.
8
20  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
Biodigestor  
pH = 1-10,  
=2-5 kg/m ,  
Temp.  
3
effluent(BDE  
of a  
COD=34 kg/m ,  
pH=1,  
Cw=3kg/m ,  
Temp.=140 C  
COD  
reduction=70%,  
BOD  
3
C
w
3
)
pH=7.8, Color  
=Blackish  
brown  
Chaudhari et  
al. (51)  
1
1
1
2
CuO  
o
molasses  
based alcohol  
distillery  
range=100-  
t
R
=6 h,  
reduction=83%  
o
1
40 C, t  
R
=0-6 h  
4 2  
CuSO .5H O,  
CuO,  
pH=2-12,  
=1-10g/L,  
Temp.  
range=60-90 C,  
=0-3 h  
pH =11, Cw=4  
g/L, Temp=  
60±2 C, t  
4
min, CuSO .  
5H  
COD=120  
Synthetic Dye mg/L,  
COD  
reduction=95%,  
Color  
C
w
4 2  
MgSO .7H O,  
Kumar et al.  
(46)  
0
R
=90  
wastewater  
color=530PCU,  
pH=6.4  
FeCl  
and  
3
, CaCl  
2
o
reduction=67.59%  
t
R
2
O
4 2  
FeSO .7H O.  
COD=3682  
mg/L,  
Color=dark  
yellow, pH=5.5  
pH=2-10,  
=2-5kg/m  
Temp.=55-  
95°C, t =0-9 h  
COD  
reduction=74%,  
Color  
Sugar  
industry  
waste water  
pH=10, Cw=4  
3
CuSO  
CuO, MnO  
4
, FeSO  
4
,
C
w
Sahu et al.  
(24)  
3
1
1
3
4
g/dm , Temp. =  
o
75 C t  
R
=9 h, CuO  
R
removal=80%.  
Rice grain-  
based  
biodigester  
effluent  
COD=11500  
mg/L, Color =  
Blakish Brown,  
pH=7.8  
pH=3.5-9.5,  
COD  
reduction=80.4%,  
Color  
pH=5, C  
w
=4  
3
CuO, CuSO  
4
,
C
w
=1-5g/dm , T  
Prajapati et  
al. (26)  
3
g/dm , Temp. =  
FeSO  
4
emp. = 65-  
o
R
95 C t =9 h, CuO  
o
100 C, t  
R
=0-9  
removal=72%  
(BDE)  
Reactive Dye  
three main  
groups  
anthraquinone,  
benzene and  
triazine groups  
Cibacron  
Blue in  
aqueous  
solution  
pH=1-12  
Cw=1-8 g/L  
Temp.=40-95 C  
CuO,copper  
sulphate,ZnO  
pH=2 C  
T=95 C CuSO  
w
=5 g/L,  
Color  
removal=65.35%  
1
1
5
6
Su et al. (47)  
o
o
4
(reactive dye)  
COD=3682  
pH=2-10,  
Cw=2-6 kg/m ,  
pH=8, Cw=5  
COD  
reduction=73%,  
Color  
Sugarcane  
industrial  
effluent  
mg/L, Color=  
350 PCU, (Dark  
Yellow), pH =  
3
3
CuO,CuSO  
CuCl  
4
,
kg/m , Temp.  
Sahu et al.  
(49)  
o
2
Temp.=55-  
=85 C, t  
CuO  
R
= 9 h,  
o
9
5 C, t  
R
= 0-9 h  
removal=76%  
5
.5  
COD=3682  
mg/L,  
Color=350 PCU FeO, and  
(Dark Yellow)  
pH=5.5  
pH=1-11,  
Cw=2-6 kg/m ,  
pH=5,  
Cw=5kg/m ,T  
emp.=85 C, t =  
R
9h, CuO  
COD  
reduction=84.2%  
Color  
Sugar  
industry  
waste water  
CuO, ZnO,  
3
3
Sahu et al.  
(27)  
1
1
7
8
o
Temp.=55-  
MnO  
o
9
5 C, t  
R
= 0-9 h  
removal=89.6%  
pH=1-9, Cw=1-  
4kg/m , T emp.  
COD=40-70  
kg/m , color =  
Dark brown  
pH=2, Cw = 4  
3
3
Distillery  
waste water  
COD  
reduction=65%  
Sharma et al.  
(35)  
3
CuO  
kg/m , T emp.=  
o
= 80-110°C, t  
0-9 h  
R
R
110 C, t = 9 h  
=
Forests (MoEF) (28). The distillery wastewaters released into  
the aquatic environment without proper treatment can cause  
harmful effects in the aquatic life by hindering the light  
penetration (29).  
3
An overview of thermolysis process for the  
treatment of industrial wastewater  
Thermal catalytic process has been recognized as an  
effective process towards the industrial wastewater treatment.  
Most of the studies have suggested this process for the  
treatment of organic compounds present in wastewater (17-18,  
In the context of thermolysis process for the treatment of  
wastewater, Daga et al. (30) have checked the efficiency of  
catalytic thermal process for the treatment of distillery  
wastewater for the first time. In their work, they have  
2
2-24). In addition to this, thermolysis process has shown its  
efficiency towards the removal of COD and color by numerous  
researchers. In recent years, performance of thermolysis  
process has been widely evaluated by many authors for the  
treatment of different industrial wastewater which have been  
summarized in Table 2.  
3
performed with COD value in the range of 95- 100 kg/m at  
temperatures range of 150-230°C. The COD removal was  
found to be an increase with an increase in temperature and  
autogenously pressure. The 30% COD was removed at 150°C  
and 50% COD reduction was achieved at 230°C in 6 h  
treatment. The obtained result indicated that the process of  
degradation kinetics was described by two stages COD  
reduction with the first stage being faster than the second one.  
The experimental data was fitted for first order kinetics with a  
3
.1 Distillery wastewater  
In India, Alcohol is manufactured by the fermentation  
process from sugar cane molasses, grains etc. which generates  
-15 L of high strength wastewater for each liter of alcohol  
8
-
1
k value of 9.72, 12.96 and 14.35 min at 150, 170 and 190°C  
produced. The effluent from distilleries is known in several  
ways as distillery spent wash (DSW), distillery wastewater  
-
1
for the first stage, and 1.46, 1.32 and 1.66 min for the second  
stage, respectively (30). They reported that an increase in  
temperature resulted in an increase in COD reduction. The  
results indicated that the COD removal efficiency was  
favorable at under acidic conditions. Lele et al. (31) conducted  
thermolysis experiment for treatment of distillery wastewater  
having a COD value of 1,08,000 mg/L at temperatures over the  
(DWW), stillage, slope, vinasse etc. depending on the distillery  
th  
unit (17). India is the 4 largest producer of ethanol over the  
world which creates 40.4 billion liters of wastewater per annum  
with the production of 3.25 billion liter of alcohol by 319  
distilleries (3). Distillery industries have been recognized in the  
“Red Category” industries by the Ministry of Environment and  
8
21  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
range of 160-250°C and autogenously pressure in a autoclave.  
The results showed maximum 50% COD reduction within 2  
hrs. Belkacemi et al. (32) carried out thermolysis process for  
the treatment of mature timothy grass based distillery  
wastewater which having total organic carbon (TOC) 22,500  
mg/L in the temperature range of 473-513 K and autogenously  
pressure in the absence of catalyst. The result revealed that  
maximum 54% TOC reduction was obtained at 513 K in 10 min  
with initial pH of 4.5. They also reported first order kinetic  
model for TOC reduction incorporated the effect of initiation-  
deactivation of catalyst during the process. Dhale et al. (33)  
have studied for the treatment of distillery waste water after  
bio-gas generation using wet oxidation at the laboratory scale.  
They have reported that 40% COD and 30% color reduction  
was obtained at 150°C and pH of 8. Chaudhari et al. (18) have  
investigated the efficiency of catalytic thermal treatment  
process in terms of COD removal from a bio-digester effluent  
of an alcohol distillery plant. They reported that maximum 70%  
COD reduction was obtained at pH of 1 using CuO catalyst at  
salt content, high chemical oxygen demand (COD) and total  
organic carbon (TOC) and toxic chemicals due to presence of  
surfactants, scouring agents, oil and grease, reactive dyes (38-  
41). The wastewater emanates from textile industries creates  
serious environmental problem such as hinders photosynthesis  
activity in plant, threat to aquatic life due to existence of metals  
and chlorine, high color hinders the light penetration and  
oxygen consumption (42). Therefore it is required to treat  
textile industry waste water before being allowed to be  
discharge in to surface waters. The conventional waste water  
treatment methods are found to be not appropriate for the  
treatment of high strength complex waste water emanating  
from textile industry (43). Thermal catalytic process may be  
an option for the treatment of textile wastewater. This process  
is very effective in color as well as COD removal. There have  
been numerous studies described in literature towards the  
treatment of synthetic dye wastewater and real industrial  
effluent using thermal catalytic process. In this context, Kumar  
et al. (21) studied the effectiveness and performance of the  
thermolysis process for the treatment of desizing wastewaters  
under moderate temperature and atmospheric pressure  
conditions. They have used in their study various types of  
1
6
40°C with initial COD =34000 mg/L for the reaction time of  
hrs. Chaudhari et al. (17) have conducted thermolysis  
3
experiments in a batch mode with a 1 dm stainless steel  
pressure reactor for COD removal from alcohol distillery  
effluent. The observed results showed that maximum COD  
4 2 4 2  
catalysts such as CuSO .5H O, CuO, ZnO, FeSO .7H O,  
Al (SO4) .16H O. They have found that maximum 71.6%  
COD and 87.2% color were removed at catalyst mass loading  
2
3
2
3
removal was found as 60% at 140°C , 3 kg/m (catalyst  
3
loading) and pH of 2. They have also found that the solid  
residue with a heating value of 21.77 MJ/kg had a C:H atomic  
ratio of 1:1.08. They have suggested that the obtained residue  
can be utilized as a fuel in the combustion furnaces and the  
obtained ash can be mixed with organic manure for the  
agriculture/horticulture purpose. Chaudhari et al. (23) studied  
the thermolysis process for the treatment of distillery  
wastewater (DWW) and bio-digester wastewater (BDE) at  
atmospheric pressure using various catalysts such as CuO, ZnO  
of 4 kg/m and pH of 4. It was also found that the pH value of  
0
the wastewater have an important effect on the precipitation  
process. Kumar et al. (22) investigated treatment of dyeing  
effluent from a cotton textile mill by thermolysis and  
coagulation process. They also compared the efficiency of  
4 4 3  
different catalysts such as CuSO , FeSO , FeCl , CuO, ZnO  
and PAC (poly aluminium chloride). It was found that CuSO  
4
was found to be most effective catalyst as compared to others.  
It was found that about 77.9% COD and 92.85% color were  
and MnO  
2
-CeO  
2
. They observed that CuO catalyst had highest  
reduced using thermal catalytic process at a catalyst mass  
3
removal efficiency as compared to all the other catalysts. The  
maximum 47% COD with 68% color reduction from DWW  
and 61% COD with 78% color reduction from BDE was  
loading (CuSO  
4
) of 6 kg/m , pH 12 and 95°C. It has been  
reported that 88% COD and 96% color reduction of thermally  
treated desizing waste water followed by coagulation were  
3
3
achieved at 100°C with 4 kg/m catalyst loading in 12 h. Kadam  
achieved using commercial alum at a coagulant dose (1kg/m )  
et al. (34) reported 80% and 92% COD reduction with 60 mg  
dose FeCl and CuSO catalyst respectively. Prajapati et al. (26)  
3 4  
at pH of 4 (44). Man et al. (45) studied thermolysis–  
coagulation–flocculation process for the reduction of color and  
COD from aqueous solution. Almost 90% of COD and 98% of  
color removal were achieved at a final pH of 10.89 and a  
studied on the treatment of rice grain based biodigestor effluent  
of the distillery unit. They have used various catalysts such as  
copper oxide, copper sulphate and ferrous sulphate during  
thermolysis process. They have observed that maximum COD  
and color removal of 80.4% and 72% respectively were found  
2
coagulant dose of 3 g MgCl /L of dye solution. Thermolysis  
followed by Coagulation–flocculation resulted in a removal of  
91.26% COD and 98.78% color at final solution pH of 10.89  
with a lesser coagulant dosage of 500 mg/L. Kumar et al. (46)  
investigated the efficiency of catalytic thermal treatment of  
synthetic dye wastewater in terms of COD and color reduction.  
They have used in their study various catalysts such as  
3
at an optimum temperature of 95°C, catalyst loading of 4 g/dm  
and pH of 5 with CuO catalyst. They have also suggested that  
the slurry found after thermolysis had good settling  
characteristics. The obtained residue may be used as a fuel in  
combustion furnaces. Sharma et al. (35) reported the maximum  
CuSO  
FeSO  
4
.5H  
.7H  
2
O, CuO, MgSO and  
O. They have observed that copper sulphate was  
4
.7H  
2
O, FeCl  
3
,
CaCl  
2
6
5% COD from distillery wastewater was reduced at an  
4
2
3
optimum pH of 2, catalyst loading of 4 kg/m , a temperature of  
10°C,. They also suggested that due to the containing of high  
found to be best catalyst in comparison to others. Almost 95%  
COD and 68% color from synthetic solutions with copper  
sulphate loading of 4 g/L in 90 min were achieved at  
temperature of 60±2°C, pH of 11 and 100 mg/L of initial dye  
concentration. Another study on dye wastewater using  
thermolysis process was reported by Su et al. (47), they  
reported that almost 66.14% color was removed at optimum  
pH of 2 and catalyst mass loading of 5 g/L.  
1
organic load in wastewater, thermolysis followed by  
electrocoagulation may be utilized for the complete treatment  
of distillery wastewater.  
3
.2 Textile wastewater  
Textile industry is one of the polluting industries over the  
world, and it consumes approximately 200 L water per kg of  
fabric processed per day (36-37). All textile industries involve  
desizing, scouring, bleaching, mercerizing, dyeing operation  
according to their requirements. These industries generate a  
huge quantity of wastewater which contains a wide range of  
pollutants in terms of high turbidity, strong color, pH, high-  
3.3 Sugar Industry Waste water  
Wastewater from sugar industry is polluted with various  
organic and inorganic molecules. The sugar industry  
wastewaters have been characterized by high COD, BOD and  
TDS. If untreated waste water is discharged to the natural water  
8
22  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
bodies, which makes the water bodies unhealthy for both  
aquatic and human usages (48). Therefore it is required to treat  
wastewater before discharging in to the environment. In recent  
years, thermal catalytic process has been employed towards the  
treatment of sugar industrial wastewater by many authors (20,  
The wastewater generated from tanning industries increases  
aquatic environmental problems due to their complex  
composition and high concentrations of several organic and  
inorganic compounds reflected in particular by high chemical  
oxygen demand (COD), strong color, dissolved and suspended  
solids, salinity, toxic chemicals etc. (53). The compositions of  
waste water coming from tanneries are highly fluctuated and  
depend on the raw materials, tanning route, the processing  
volume, the amount of water utilized and hide/skin preservation  
process. The contamination of water bodies with highly  
concentrated tannery wastewater is a major issue because of  
hostile effects on aquatic life and human health. Therefore, it is  
necessary to treat such type of wastewater before discharge in  
to water bodies. Thermolysis process as an effective treatment  
option has been taken in this study for the treatment of tannery  
wastewater. Thermal catalytic process is a chemical process, in  
which a substance (complex organic compounds + catalyst +  
2
4, 27, 49-51). In this regards, Garg et al. (20) studied  
thermochemical precipitation for the COD and color removal  
from pulp and paper mill wastewater using copper sulphate as  
a catalyst. The obtained result showed that a maximum COD  
reduction of 63.3% was achieved with a catalyst loading of 5  
3
kg/m , whereas the maximum 92.5% color was removed using  
-3  
a CuSO loading of 2 kg m at an optimal solution pH of 5.0.  
4
Sahu et al. (24) investigated the treatment of sugar industry  
wastewater for the COD and color removal using catalytic  
thermal process. They found that maximum 74 % COD and 80  
%
color reduction were obtained using copper oxide as a best  
3
catalyst at catalyst mass loading of 4 kg/m , pH of 10 and  
temperature of 75°C. Sahu (27) compared the performance of  
different metal oxides such as copper oxide, zinc oxide, ferrous  
oxide and manganese oxide towards the treatment of sugar  
industry wastewater using thermolysis process as pretreatment  
step. The results showed this process with copper oxide gave  
2
H O) is decomposed into other substances (solid residue,  
smaller organic compounds, water, gas) the application of heat  
(21, 22, 45). The main objective of this study is to evaluate the  
efficiency of thermal catalytic process in terms of the COD and  
color reduction from tannery wastewater.  
8
4.2% COD and 89.6% color removal at catalyst concentration  
3
of 5 kg/m , solution pH of 5, reaction time of 9 h and  
temperature 85°C. It was reported that the obtained sludge after  
thermolysis has high heating values and can be further used as  
a fuel (27). Sahu (49) illustrated the reduction of chemical  
oxygen demand and color from sugarcane industry wastewater  
using thermolysis and coagulation method. Only thermolysis  
process gave maximum 73% of COD and 76% color removal  
from sugar industry wastewater at catalyst (copper oxide)  
4.2 Materials and methods  
4.2.1 Chemicals  
All the chemicals used in this study were of analytical grade  
(AR) and purchased from Kumar Chemicals, India. Ferrous  
sulphate (FeSO  
Sulphate (CuSO  
4
.7H  
.5H  
2
3
O), Ferric Chloride (FeCl ), Copper  
O), Copper oxide (CuO) and Zinc Oxide  
4
2
(ZnO) were used as catalyst for thermal catalytic treatment  
process. Potassium dichromate, silver sulfate, ferrous  
ammonium sulfate heptahydrate, concentrated sulfuric acid,  
mercuric sulfate and ferroin indicator were used in COD  
analysis.  
3
loading of at 5 kg/m , temperature of 85°C, reaction time of 9  
h and pH of 8. Whereas, 97.6% COD and 99.9% color were  
removed using thermolysis followed by coagulation method at  
pH of 6.5 and mass loading of 8 mM with copper sulfate salt.  
It was suggested that thermolysis followed by coagulation  
method may be an alternative option for the treatment of real  
industrial effluent. Sahu et al. (50) evaluated the performance  
of thermolysis and electrocoagulation process on sugar industry  
wastewater. They reported that maximum 75.6% of COD and  
4.2.2 Tannery wastewater  
The raw effluent was collected from leather industry  
located in the Kanpur, India (details not provided due to  
confidentiality issues). The effluent sample was yellowish-  
brown in color and kept at 4±1°C in the laboratory. The  
characterization of the wastewater has been shown in Table 3.  
7
9.2% of color content were achieved using thermolysis  
process whereas 97.8% of COD and 99.7% of color were  
obtained with combined thermal and electrocoagulation  
process under optimum conditions.  
Table 3: Characteristics of the tannery wastewater  
Parameters  
Values  
Units  
In all, it can be concluded that based on above studies,  
thermolysis process has shown its efficiency towards the  
treatment of different wastewater. Also, various other processes  
such as coagulation, electrocoagulation process etc. can be  
coupled with thermolysis process in order to enhance its  
performance and efficacy. It can be said that the organic  
pollutants from wastewater can be treated successfully using  
thermolysis process, and it can be employed other similar dyes  
wastewater as well as real industrial effluent. Therefore, a real  
sample from tannery industry has been taken in order check the  
performance and efficiency of thermolysis process in  
subsequent section 4.  
pH  
5.8  
–
Color  
Yellowish brown  
–
COD  
5970  
11360  
9740  
1620  
35.2  
mg/L  
mg/L  
mg/L  
mg/L  
mS/cm  
NTU  
Total solids (TS)  
Total dissolved solids (TDS)  
Total suspended solids (TSS)  
Electrical conductivity  
Turbidity  
286  
4
.2.3 Analytical Method  
The chemical oxygen demand (COD) of the sample was  
measured as per the standard of APHA method (54). Solution  
pH was regulated using 1 N NaOH and 1 N H SO . Total solids  
TS) were estimated by drying the effluent sample at 104 °C  
2
4
(
4
Treatment of Tannery wastewater using  
in hot air oven (Make: Macro Scientific Works Pvt. Ltd.).  
Total dissolved solids (TDS), conductivity and turbidity were  
measured using ion meter (Hanna Instruments, USA). Solution  
pH was determined by a pH meter (Hanna Instruments, USA).  
To determine the color removal efficiency, absorbances of the  
sample were measured using a UV–vis double beam  
spectrophotometer (Model: NSP372) at 475 nm.  
thermolysis process: A case study  
4
.1 Introduction  
The leather industry has a major relevance in Indian  
economy and contributes significantly towards exports,  
employment generations. However, these industries are  
typically recognized as most polluting wastewater generated  
industries (52). A typical tanning processing comprises of  
beamhouse operation, tanyard, retanning and finishing process.  
8
23  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
4
.2.4 Experimental Setup and procedure  
The schematic of the thermal catalytic reactor set-up used  
decrease in pH except for CuO and ZnO. This may be due to  
the dissociation of sulphate/chlorides and thus creating  
sulfuric acid/hydrochloride which reduces the pH of the  
solution (22).  
Hence, it can be concluded from the above case study that  
the thermolysis process may be an effective process for the  
treatment of real industrial wastewater. Thus, on the basis of  
above result found in this work with earlier studies for the  
treatment of industrial wastewater using thermolysis, it has  
been proven that thermal catalytic process has potential  
towards the treatment of the highly polluted industrial  
wastewater.  
in the present work is shown in Fig. 2. Thermal catalytic reactor  
set up consists: (1) a 0.5 L capacity three necked round bottom  
flask (2) the rotamantle with both heating and speed controlling  
knob (3) a long vertical water cooler condenser was connected  
at the center of the atmospheric glass reactor to condense the  
vapors and recirculate into the glass reactor to prevent any loss  
of the vapor generated during the reaction (4) a mercury  
thermometer was inserted into the glass reactor to measure the  
reaction mixture temperature (5) one neck of the glass reactor  
was used for sample withdraw. In this study, all experiments  
were performed for treating 300 ml volume of tannery waste  
water sample. The effect of solution pH on the removal of COD  
and color was studied over a pH range of 2.0–11.0 to optimize  
5
Conclusions  
The thermolysis process is found to be an environmental  
3
the pH. The desired amount of the catalyst (2 kg/m ) was added  
friendly process for the treatment of industrial wastewater. It  
can be signified as an effective tool for the treatment of  
organic, inorganic and larger complex molecules present in  
various industrial wastewaters.  
to the wastewater sample and temperature was kept at 95°C.  
The reaction time was 5 h for all the experiments. After the start  
of an experiment five millimeters of the samples were taken  
from the reactor at a regular interval of time and analyzed for  
COD and color. The % removal of COD and color was  
calculated using following Eq. (1):  
i
C Cf  
Eq. (1)  
Removal (%)  
x100  
Ci  
where, C and C = Initial and final concentration respectively  
i f  
(mg/L).  
4
.3 Results and discussions  
Initial pH is an important parameter in deciding the  
efficiency of thermolysis process. Thermolysis process  
strongly depend on the initial pH for the treatment of textile  
industry wastewater (22), pulp and paper wastewater (20),  
sugar industry wastewater (24, 50), synthetic dye wastewater  
(
46) and petrochemical wastewater (19). Therefore, in this  
case study, the effect of initial pH on thermolysis of the  
wastewater with copper sulphate (CuSO .5H O), ferric  
chloride (FeCl ), copper oxide (CuO), ferrous sulphate  
FeSO .7H O), zinc oxide (ZnO) and without catalyst was  
4
2
3
(
4
2
investigated in a batch mode at the atmospheric pressure and  
at 95°C. All the experiments were conducted for a reaction  
3
time of 5 h with the catalyst mass loading (C  
w
) of 2 kg/m . The  
Figure 2: Experimental set-up of thermal catalytic process  
initial pH was varied in the experiments over a range of 2–12.  
The obtained results are shown in Fig. 3 and Fig. 4. A sample  
from treated wastewater was collected after each experiment  
and sludge was allowed to settle down. Then, the supernatant  
was taken for the measurement of its COD and color. It can be  
seen from figure (3) and (4) that all the catalysts i.e.  
7
6
5
0
0
0
CuSO₄.5H₂O  
FeCl₃  
CuO  
FeSO₄.7H₂O  
ZnO  
40  
Without catalyst  
4 2 4 2  
CuSO .5H O, FeCl3, CuO, FeSO .7H O and ZnO exhibited  
30  
20  
10  
0
high removal efficiency of COD and color under acidic  
solution in comparison to basic conditions of the solution.  
Maximum 65.25% COD and 72.65% color reduction were  
obtained in case of copper sulphate salt at pH of 4. Ferric  
chloride has shown 45.36% COD, 58.32% color reduction at  
pH of 4. Copper oxide provided 47.65% COD and 56.32%  
color reduction at pH of 6. Ferrous sulphate and zinc oxide  
have shown 40.25% COD and 45.26% color reductions, and  
0
2
4
6
8
10  
12  
14  
Initial pH  
Figure 3: Effect of solution pH on COD reduction of the tannery  
wastewater by thermolysis (Experimental conditions: COD = 5970  
mg/L, temperature = 95°C, reaction time = 5 h, catalyst mass loading  
0
2
5.23% COD and 30.25% color reduction at pH of 6  
3
(C  
w
) = 2 kg/m )  
respectively. When the tannery wastewater was heated in the  
absence of catalysts at the similar conditions, the maximum  
This paper provides information about the recent research  
1
2.65% COD and 15.46% color were reduced at pH of 8. The  
on thermal catalytic process for the treatment of synthetic as  
well as real industrial wastewater. In a case study presented in  
this paper, the treatment of tannery wastewater using  
thermolysis process shows that it can degrade and mineralize  
the organic molecules which are hardly treatable by  
random reduction in COD values was also found for treatment  
of various industrial wastewaters by numerous researchers (17,  
1
8, 20, 21, 22). It has also been observed that the after the  
treatment final pH was also measured and found to be a  
8
24  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
conventional treatment techniques. The obtained results based  
on case study (treatment of tannery wastewater using  
thermolysis) showed that maximum 65.25% COD and 72.65%  
color were reduced using copper sulphate salt with catalyst  
[15]Brink A, Sheridan C, Harding K. Combined biological and  
advance oxidation processes for paper and pulp effluent treatment.  
S. Afr. J. Chem. Eng. 2018;25:116-122.  
[
16]Oller I, Malato S, Sánchez-Pérez JA. Combination of Advanced  
Oxidation Processes and biological treatments for wastewater  
decontamination—A review. Sci. Tot. Environ. 2011;409:4141–  
3
mass loading of 2 kg/m at pH of 4. In all, it can be said that  
thermolysis process can be used as an effective treatment  
process for the treatment of other synthetic as well as real  
industrial wastewater.  
4
166.  
[17]Chaudhari PK, Mishra IM, Chand S. Effluent treatment for alcohol  
distillery: Catalytic thermal pretreatment (catalytic thermolysis)  
with energy recovery. Chem. Eng. J. 2008;136 (1):14-24.  
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
[18]Chaudhari PK, Mishra IM, Chand S. Catalytic Thermal Treatment  
CuSO₄.5H₂O  
FeCl₃  
(Catalytic Thermolysis) of a Biodigester Effluent of an Alcohol  
Distillery Plant. Ind. Eng. Chem. Res. 2005;44:5518-5525.  
CuO  
[
[
[
19]Verma S, Prasad B, Mishra IM. Thermo chemical treatment  
FeSO₄.7H₂O  
ZnO  
(
thermolysis) of petrochemical wastewater: COD removal  
mechanism and floc formation. Ind. Eng. Chem. Res. 2011;50  
9):5352-5359.  
Without Catalyst  
(
20]Garg A, Mishra IM, Chand S. Thermochemical Precipitation as a  
Pretreatment Step for the Chemical Oxygen Demand and Color  
Removal from Pulp and Paper Mill Effluent. Ind. Eng. Chem. Res.  
2005;44:2016-2026.  
21]Kumar P, Prasad B, Mishra IM, Chand S. Catalytic thermal  
treatment of desizing wastewaters. J. Hazard. Mater.  
2007;149:26–34.  
0
2
4
6
8
10  
12  
14  
Initial pH  
Figure 4: Effect of solution pH on color reduction of the tannery  
wastewater by thermolysis (Experimental conditions: COD = 5970  
mg/L, temperature = 95°C, reaction time = 5 h, catalyst mass loading  
0
[22]Kumar P, Prasad B, Mishra IM, Chand S. Treatment of composite  
wastewater of a cotton textile mill by thermolysis and coagulation.  
J. Hazard. Mater. 2008;151:770-779.  
3
w
(C ) = 2 kg/m )  
[
23]Chaudhari PK, Singh RK, Mishra IM, Chand S. Kinetics of  
catalytic thermal pretreatment (catalytic thermolysis) of distillery  
wastewater and bio-digester effluent of alcohol production plant at  
atmospheric pressure. Int. J. Chem. React. Eng. 2010;8:1-22.  
24]Sahu OP, Chaudhari PK. Removal of color and chemical oxygen  
demand from sugar industry wastewater using thermolysis  
processes. Desalination and Water Treatment 2015;56:1758–  
References  
[
1] Rajasulochana P, Preethy V. Comparison on efficiency of various  
techniques in treatment of waste and sewage water  
comprehensive review. Resour. Efficient Technol. 2016;2:175–  
84.  
–
A
[
1
[
[
[
[
[
[
[
[
[
[
[
2] Singh NB, Nagpal G, Agrawal S, Rachna. Water purification by  
1
767.  
using Adsorbents: A Review. Environ. Technol. Innovation.  
[
[
25]Sahu O, Paul D, Chaudhari PK. A Comparatively Study on  
Thermal and Advance Oxidation Wastewater Treatment Process:  
Review. J. Chem. Eng. Chem. Res. 2014;1( 6):353-364.  
26]Prajapati AK, Chaudhari PK, Mazumdar B, Choudhary R.  
Catalytic thermal treatment (catalytic thermolysis) of a rice grain-  
based biodigester effluent of an alcohol distillery plant. Environ.  
Technol. 2015;36(20):2548–2555.  
27]Sahu O. Catalytic thermal pre-treatments of sugar industry  
wastewater with metal oxides: Thermal treatment. Exp. Therm.  
Fluid Sci. 2017;85:379–387.  
28]Tewari PK, Batra VS, Balakrishnan M. Water management  
initiatives in sugarcane molasses based distilleries in India. Res.  
Conserv. Recycl. 2007;52:351–367.  
29]Mohan S, Achary BK, Madamwar D. Distillery spent wash:  
Treatment technologies and potential applications. J. Hazard.  
Mater. 2009;163:12–25.  
2
018;11:187–240.  
3] Pant D, Adholeya A. Biological approaches for treatment of  
distillery wastewater: Review. Bioresour. Technol.  
007;98:2321–2334.  
A
2
4] Gadipelly C, Gonzalez AP, Yadav GD, et al. Pharmaceutical  
industry waste water: Review of the technologies for water  
treatment and reuse. Ind. Eng. Chem. Res. 2014;53:11571-11592.  
5] Rajoriya S, Carpenter J, Saharan VK, Pandit AB. Hydrodynamic  
cavitation: An advanced oxidation process for the degradation of  
bio-refractory pollutants. Rev. Chem. Eng. 2016;32(4):379-411.  
6] Abdelfattah I. Treatment of Highly Polluted Industrial Wastewater  
Utilizing Clean and Low Cost Technologies: Review Article. J.  
Environ. Acc. Manage. 2018;6(2):167-184.  
7] Carlos A, Huitle M, Brillas E. Decontamination of wastewaters  
containing synthetic organic dyes by electrochemical methods: A  
general review. Appl. Catal., B: Environ. 2009;87:105–145.  
8] Sundarapandiyan S, Chandrasekhar R, Ramanaiah B, Krishnan S,  
Saravanan P. Electrochemical oxidation and reuse of tannery saline  
wastewater. J. Hazard. Mater. 2010;180:197–203.  
9] Benhadji A, Ahmed MT, Maachi R. Electro coagulation and effect  
of cathode materials on the removal of pollutants from tannery  
wastewater of Rouïba. Desalination. 2011;277:128–134.  
10]Ahmed MJ, Theydan SK. Equilibrium isotherms, kinetics and  
thermodynamics studies of phenolic compounds adsorption on  
palm-tree fruit stones. Ecotoxicol. Environ. Saf. 2012;84:39–45.  
11]Yadav SK, Singh DK, Sinha S. Chemical carbonization of papaya  
seed originated charcoals for sorption of Pb(II) from aqueous  
solution. J. Environ. Chem. Eng. 2014;2:9–19.  
[
[
[
[
[
[
30]Daga NS, Prasad CVS, Joshi JB. Kinetics of Hydrolysis And Wet  
Air Oxidation Of Alcohol Distillery Waste. Indian Chem. Eng.  
1
986;28:22–31.  
31]Lele SS, Rajadhyaksha PJ, Joshi JB. Effluent treatment for alcohol  
distillery: Thermal pretreatment with energy recovery. Environ.  
Prog. 1989;8:245–252.  
32]Belkacemi K, Larachi F, Hamoudi S, Turcotte G, Sayari A.  
Inhibition and deactivation effects in catalytic wet oxidation of  
high- strength alcohol-distillery liquors. Ind. Eng. Chem. Res.  
1
999;38(6):2268–2274.  
[
[
[
33]Dhale AD, Mahajani VV. Treatment of distillery waste water after  
bio-gas generation: wet oxidation. Ind. J. Chem. Technol.  
2
34]Kadam A, Upadhyay K. Wastewater treatment of alcohol distillery  
000;7(1):11-18.  
12]Lofrano G, Meriç S, Zengin GE, Orhon D. Chemical and  
biological treatment technologies for leather tannery chemicals and  
wastewaters: A review. Sci. Total Environ. 2013;461–462:265–  
plant by catalytic thermolysis. J. Ind. Pollut. Control  
2
012;28(1):51-56.  
2
81.  
35]Sharma D, Prajapati AK, Chaudhari R, Kaushal RK, Pal D,  
Sawarkar AN. Preparation and characterization of CuO catalyst for  
the thermolysis treatment of distillery wastewater. Environ.  
Technol. 2018;39:2607-2612.  
36]Wang Z, Xue M, Huang K, Liu Z. Textile Dyeing Wastewater  
Treatment. Advances in Treating Textile Effluent. 2011;5:91-116.  
37]Kant R. Textile dyeing industry an environmental hazard. Natural  
Sci. 2012;4 (1):22-26.  
[
[
13]Fazal S, Zhang B, Zhong Z, Gao L, Lu X. Membrane Separation  
Technology on Pharmaceutical Wastewater by Using MBR  
(Membrane Bioreactor). J. Environ. Prot. 2015;6:299-307.  
14]Tekin H, Bilkay O, Ataberk SS, et al. Use of Fenton oxidation to  
improve the biodegradability of a pharmaceutical wastewater. J.  
Hazard. Mater. 2006;B 136:258–265.  
[
[
8
25  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 2, Pages: 818-826  
[
[
38]Verma AK, Dash RR, Bhunia P. A review on chemical  
coagulation/flocculation technologies for removal of colour from  
textile wastewaters. J. Environ. Manage. 2012;93:154-168.  
39]Dos Santos AB, Cervantes FJ, Van Lier JB. Review paper on  
current technologies for decolourisation of textile wastewaters:  
Perspectives for anaerobic biotechnology. Bioresour. Technol.  
2
007;98:2369–2385.  
[
[
40]El-Gohary F, Tawfik A. Decolorization and COD reduction of  
disperse and reactive dyes wastewater using chemical-coagulation  
followed by sequential batch reactor (SBR) process. Desalination  
2
009;249:1159–1164.  
41]Naik DJ, Desai HH, Desai TN. Characterization and treatment of  
untreated wastewater generated from dyes and dye ingredients  
manufacturing industries of Sachin industrial area, Gujrat, India. J.  
Environ. Res. Dev. 2013;7 (4A):1602-1605.  
[
[
[
[
42]Holkar CR, Jadhav AJ, Pinjari DV, Mahamuni NM, Pandit AB. A  
critical review on textile wastewater treatments: Possible  
approaches. J. Environ. Manage. 2016;182:351-366.  
43]Olayinka K. Studies on industrial pollution in Nigeria: The effect  
of textile effluents on the quality of groundwater in some parts of  
Lagos. Nigerian J. Health and Biomedical Sci. 2004;3:44-50.  
44]Kumar P, Prasad B, Chand S. Treatment of desizing wastewater by  
catalytic thermal treatment and coagulation. J. Hazard. Mater.  
2
009;163:433–440.  
45]Man LW, Kumar P, Teng TT, Wasewar KL. Design of  
experiments for Malachite Green dye removal from wastewater  
using thermolysis – coagulation–flocculation, Desalination and  
Water Treatment. 2012;40:260–271.  
[
[
[
[
[
46]Kumar P, Agnihotri R, Mondal MK. Catalytic treatment of  
synthetic dye wastewater: COD and color reduction. J. Environ.  
Chem. Eng. 2013;1:440–447.  
47]Su CXH, Teng TT, Wong YS, Morad N, Rafatullah M. Catalytic  
thermolysis in treating Cibacron Blue in aqueous solution: Kinetics  
and degradation pathway. Chemosphere 2016;146:503-510.  
48]Kushwaha JP. A review on sugar industry wastewater: sources,  
treatment technologies, and reuse. Desalination and Water  
Treatment. 2015;53:309-318.  
49]Sahu O. Treatment of industry wastewater using thermo-chemical  
combined processes with copper salt up to recyclable limit. Int. J.  
Sustain. Built Environ. 2016;5:288–300.  
50]Sahu O, Rao DG, Thangavel A, Ponnappan S. Treatment of sugar  
industry wastewater using  
electrocoagulation processes. Int. J. Sustain. Eng. 2018;11(1):16–  
5.  
a combination of thermal and  
2
[
[
[
51]Chaudhari PK, Chand S, Mishra IM. Kinetics of Catalytic Thermal  
Treatment (Catalytic Thermolysis) of Biodigester Effluent of an  
Alcohol Distillery Plant. Chem. Eng. Comm. 2012;199:874–888.  
52]Chowdhury M, Mostafa MG, Biswas TK, Saha AK. Treatment of  
leather, industrial effluents by filtration and coagulation processes.  
Water Resour. Ind. 2013;3:11–22.  
53]Religa P, Kowalik A, Gierycz P. Application of nanofiltration for  
chromium concentration in the tannery wastewater. J. Hazard.  
Mater. 2011;186:288–292.  
[
54]  
APHA, AWWA, WPCF, Standard Methods for the  
th  
Examination of Water and Wastewater, 20 ed., American Public  
Health Association, Washington, DC, 1998.  
8
26