A DOCUMENT ON VARIOUS
TYPES OF ADVANCED
OXIDATION PROCESS
By –
Sukhinder pal
Maninder Motwani
Suresh Tiwari
Abstract
Dye removal from wastewater is a key environmental concern because of the adverse impacts
that these compounds can have on aquatic ecosystems and human health. The management and
disposal of concentrated wastewater, particularly dye-containing wastewater, poses significant
environmental issues from generation to disposal. Conventional water treatment procedures
including filtration, flotation, and adsorption are non-destructive physical separation processes.
To tackle these emerging contaminants, advanced oxidation processes such as photo-Fenton,
Sonolysis, Photocatalysis, Fenton Oxidation, and ozonation etc. have been applied to remove
Dyes. These processes utilize the high reactivity of hydroxyl radicals to progressively oxidize
organic compounds to innocuous products. This review provides an overview of the findings
from recent studies, which have applied AOPs to degrade Dye compounds. Included is a
discussion
that Ozonation and Photocatalysis are effective in degrading Waste water
containing Dye. This review furthermore highlights the success of AOPs in the removal of
different dyes from Textile waste water effluents and recommendations for future studies are
outlined.
Keywords :- AOPs, Ozonation, Photocatalysis, Text Tile waste water
Table of content
Chapter No.
Content
Page No
List of Figure
List of Tables
1.
Introduction
1
2.
Literature Review
2
3.
Problem Statement and Objective
5
4.
5.
Various types of AOP
AOP Description’s
6
9
5.1 Fenton
9
5.2 Photo fenton
10
5.3 Ozonation
12
5.4 Sonolysis
14
5.5 UV Based
5.6 Wet air oxidation
16
18
5.7 Adsorption
19
6.
Comparison of various AOP method
21
7.
Advantages and Applications
22
8.
Future work
23
References
24
List of Figures
Fig.no
Name
Page No.
4.1
Various methods of AOP’s
10
5.1
Schematic diagram of Fenton process
11
5.4
Sonolysis process
16
5.6
Wet air oxidation Process
19
5.7
Adsorption process
20
List of Tables
Sr. No
Name
Page No
2.1
Literature
04
6.1
Comparison of AOP
21
Chapter 1
Introduction
Dyes are essential to the dyeing and textile industries. Over 100,000 commercially available
synthetic dyes are commonly utilised in these industries.1, 2 Dyes are mostly generated from
coal tar and petroleum intermediates, with an annual production of over 7×105 tons.3 Textile
waste effluents discharge around 15% (1,000 tons) of non-biodegradable textile dyes into
natural streams and bodies of water annually.4 Each kilogram of cloth treated in dyeing and
finishing operations consumes around 120-280 L of water According to Konstantinou and
Albanis, industrial and textile dyes are among the most hazardous chemical substances.5 The
textile finishing and dyeing industries contribute significantly to water pollution (17-20%),
according to World Bank estimates.6 Kant's study found that 72 of the primary hazardous
compounds in wastewater were primarily generated by textile dyeing, with approximately 30
of these substances being untreatable.7 In 1974, the Ecological and Toxicological Association
of the Dyestuffs Manufacturing Industry (ETAD) was established to protect consumers and the
environment by collaborating with the government to address concerns about the toxicological
impact of their products. In an ETAD survey, 90% of 4000 tested dyes were found to LD50
values exceed 2 ×103 mg/kg. The highest rates were seen in diazo, direct, and basic dyes.Azo
dyes are the most common type of colorants, accounting for about 50% of all dyes used in
industry. Azo dyes have a double bond of 40 nitrogen atoms (-N=N-), with at least one
connected to an aromatic group (such as naphthalene or benzene rings).
1
Chapter 2
Literature Review
Existing Literature:
LITERATURE REVIEW
1. Siti Zuraida, M.1, Nurhaslina,C.R.2 , Ku Halim Ku Hamid2, 2319-183X, (Print) 23191821 Volume 2, Issue 5(May 2013), PP.01-07 …. this work showed that bacteria species,
Lactobacillus delbruckii possessed impressive decolorization efficiency. ]The color removal
was dependent on the dye concentration, pH and temperature and the optimal conditions for dye
removal were 10 ppm, 6 and 37°C, respectively. It can be concluded that, Lactobacillus
delbruckii is the highly promising and suitable microorganisms to use in the treatment of
solution containing dye. However, more studies are essential prior to employing this method
commercially in the real textile industry. (P10)
2. Sobhan Ghanbari1,2 · Ali Fatehizadeh1,3 · Mehdi Khiadani
Ensiyeh Taheri1,3 ·
Hafz M. N. Iqbal5….. study demonstrates the efficacy and feasibility of dye removal in real
textile wastewater using UV/Chlorine/Br process followed by activated carbon adsorption. Dye
removal efficiency using UV/Chlorine/Br process varied at different solution pH and the highest
removal efficiency achieved at alkaline condition spatially at pH 8.3 that is the actual pH of
examined wastewater. When the bromide doses increased to 1.25 m Mol, the highest removal
efficiency (82.70%) was achieved and then efficiency decreased when the bromide dose
increased to greater than 1.25 mMol/L. Dye residue along with its degradation byproducts was
removed by the post AC adsorption. (P7)
3. Zarafshan Ali 1 , Amir Ikhlaq 1,* , Umair Yaqub Qazi 2,* , Asia Akram 3 , Iftikhar UlHasan 4 , Amira Alazmi 5 , Fei Qi 6 and Rahat Javaid 7,* This study compared the
efficiencies of the ozonation and catalytic ozonation processes for the removal of disperse
yellow 42 dye from an aqueous solution. Using Fe- and Mn-loaded (bimetallic) sodium zeolite,
the catalytic ozonation process proved to be an efficient method for dye removal. The highest
catalytic removal was achieved by catalytic ozonation (73%), followed by ozonation (30%),
and adsorption (15%). A catalyst dose of 0.5 g at a pH of 6 and with a maximum ozone supply
rate of 1.8 mg/min was considered as the optimized condition. The COD removal efficiency in
the real textile wastewater was 59% with the ozonation process, which increased to 79% after
catalytic ozonation. (P3)
4. Mehrangiz Pourgholi 1 , Reza Masoomi Jahandizi 2* , Mohammadbagher Miranzadeh 3
, Ommolbanin Hassan Beigi 1 , Samaneh Dehghan
The results of this research showed that dye removal using AOP has impact and COD based
on the type of process and reaction time in UV/H2O2/O3 by 30 minute time duration, was the
most effective method. UV/H2O2 in 10 minute time duration was the least effective method.
COD and color removal, based on the process in UV/H2O2/O3 and pH = 6 was the most
2
effective. The effect of UV/H2O2 and pH = 4 was the least efficient method on dye material
removing. Results showed that the treatment time was effective on color removing (P < 0/001)
statistically. (P6)
5. Zahid Mehmood a , Hafsa Khurshid a , Zanib Khurshid b , Muhammad Aamir a , Mehwish
Khan a Vol 5, no 2, pp 2955-2968 February 2024….dye-containing wastewater, poses
significant environmental issues Photocatalysis has proven efficient approach for dye
degradation in wastewater treatment operations. Photocatalysis is a method that uses light
irradiation and a semiconductor photocatalyst. Photocatalysis is a method that uses light
irradiation and a semiconductor photocatalyst, semiconductor materials, such as TiO2, ZnO,
Fe2O3, SnO2, ZrO2, CdS, and ZnS, have been utilised as catalysts to degrade organic
contaminants and dyes. DYE:- Procion Blue HERD (PBH) photo catalyst:-TiO2 and ZnO
Conditions:-UV lamp (30W); [PBH]0 = 10–100 ppm; photocatalyst loading = 0.5–2 g/L; pH 2–
10 Degradation:-100% decolorization of dye with ZnO at pH 7 and with TiO2 at pH. (P5)
6. Anna Lanzetta 1 , Stefano Papirio 1 , Armando Oliva 1 , Alessandra Cesaro 1,* , Luca Pucci
2 , Emanuele Mariano Capasso 2 , Giovanni Esposito 1 and Francesco Pirozzi 1 …After
investigating the effects of ozonation at different contact times (15, 30, and 45 min) and under
two pH conditions (uncontrolled and pH 10) on the decolorization results illustrate that the
highest color REs of 100, 90, and 26% were obtained for E1, E2, and E3, respectively, after 45
min and at pH 10, COD REs of 51, 31, and 33% were achieved for E1, E2, and E3, respectively.
t an ozonation stage could be proposed as a post-treatment for a biologically processed effluent
within the urban WWTP without any alkali dosage. highest color removal efficiencies (REs)
(>90%) were obtained with urban wastewater after a 45 min contact time and at pH 10. (P12)
7. R. F. Momin1 , P. B. Patil2 , S. Raut Jadhav3,(IJRASET), Volume 5 Issue VI, June 2017.
In the present study, degradation of Acid Blue 80 (AB80) was carried out by using Ultrasound
Cavitation. The effect of various operating parameters such as effect of amplitude, effect of
initial pH of solution, operating volume and effect of
temperature on the degradation rates were studied. The 34.94% degradation of AB80 was
found at the optimized conditions of amplitude, pH, temperature and volume of 75%, 2.5, 30
⁰C and 200 mL respectively. (P11)
3
LITERATURE REVIEW TABLE
SR Process
No
pH
Temp BOD COD
TDS
ELECTRICAL
Time Degradation References
CONDUCTIVITY
%
1
Photolysis
38.3
2560
280
1295.4 2920
4.26
2
Fenton
24
2550
50500
1002000
5002000
1000-10000
3
Photocatalysis
5.9 2560
3050
50100
5002000
1000-10000
4
Ozonation
67
2040
30
50
500
2000
5
Sonolysis
39
2560
___
___
___
___
Table 2.1
4
S.S Gupta
30180
90-99
H.A
Brillas
90
MA Ghazi
30
90-99
M.N
Malik
___
___
S.T Martil
Chapter 3
Problem statement and Objectives
3.1 Problem Statement
Dye wastewater is a problem because it can have harmful effects on the environment and
human health: Dyes can make water bodies appear colored, which can prevent sunlight from
reaching the photic zone. This can negatively impact the growth of algae and aquatic plants.
Dyes can be toxic to plants and animals. Fish and other aquatic creatures can ingest dyes, which
can be metabolized into hazardous substances that can harm them and their predators.Dyes can
be harmful to humans if they are ingested or come into contact with the skin. The intestinal
microflora in the human gastrointestinal tract can convert azo dyes into toxic amino acids.
Wastewater treatment plants contribute to greenhouse gas emissions, which are linked to
climate change. This research aims to address the pressing problem of Dye containing
wastewater treatment by employing Advanced Oxidation Processes (AOPs), which utilize
highly reactive oxidants to break down recalcitrant organic compounds. The challenges
encompass the identification of optimal AOPs, determining the most effective catalysts,
understanding reaction kinetics, and assessing the economic and environmental feasibility of
AOP-based treatment at an industrial scale.
3.2 Objective
The main objective of using advanced oxidation processes (AOPs) to treat dye wastewater is to
degrade organic pollutants and remove contaminants:
•
Degrade Organic Pollutants: - AOPs use hydroxyl radicals to break down organic pollutants
into carbon dioxide and water.
•
Remove contaminants: - AOPs can remove organic and inorganic contaminants from
wastewater
•
Increase Biodegradability: - AOPs can make wastewater more biodegradable.
5
Chapter 4
Various Types of AOP’s
4.1 Various methods of AOP for water treatment
Fig 4.1- Various methods of AOP for water treatment
1. Sonolysis
•
Sonolysis is a process that involves the use of ultrasound waves to induce chemical
reactions or physical changes in a substance.
•
Ultrasound waves, which have frequencies above the range of human hearing, can
create high-frequency pressure waves in a liquid or solution.
•
These waves can lead to the formation of tiny bubbles or cavities, which can collapse
violently in a process known as cavitation.
•
This cavitation can generate localized high temperatures and pressures, which can drive
various chemical reactions or disrupt molecular structures in the material being treated.
•
Sonolysis has applications in various fields, including chemistry, materials science, and
wastewater treatment.
6
2. Fenton
•
The Fenton process is an advanced chemical oxidation method used for the treatment
of contaminated water and wastewater.
•
(typically, ferrous sulfate, FeSO4) to generate highly reactive hydroxyl radicals (·OH)
through a series of chemical reactions.
•
These hydroxyl radicals are strong oxidants that can rapidly degrade and remove
various organic and inorganic contaminants from water.
3. Photo Fenton
•
The Photo-Fenton process is an advanced oxidation technique used for the treatment of
water and wastewater.
•
It combines the Fenton reaction, which involves the use of hydrogen peroxide (H2O2)
and iron ions (Fe2+ or Fe3+), with the addition of ultraviolet (UV) or visible light to
enhance the generation of highly reactive hydroxyl radicals (·OH).
•
This process is particularly effective in degrading and removing organic and inorganic
contaminants from water.
4. UV Based
•
UV-based Advanced Oxidation Processes (AOPs) combine ultraviolet (UV) light with
other chemical processes to create highly reactive hydroxyl radicals (·OH) for the
purpose of advanced water treatment.
•
These AOPs use UV light as a key component to generate these radicals, which are
strong oxidants capable of breaking down a wide range of organic and inorganic
contaminants in water. Here are a couple of UV-based AOPs.
5. Ozonation
•
Ozonation as an Advanced Oxidation Process (AOP) is a water treatment method that
utilizes ozone (O3) to generate highly reactive oxygen radicals for the oxidation and
removal of contaminants from water and wastewater.
•
It is an effective and widely used technique for treating various types of water,
7
•
including drinking water, industrial wastewater, and groundwater remediation.
6. wet air oxidation
•
Wet air oxidation (WAO) is considered an advanced oxidation process (AOP). Advanced
oxidation processes are a group of chemical treatment methods used to remove organic
and inorganic contaminants from water and wastewater.
•
WAO is one of these AOPs. It involves the use of elevated temperatures and pressures,
along with the presence of oxygen, to break down and oxidize organic compounds
present in wastewater. By doing so, it helps in the removal of pollutants and the
purification of water.
•
Advanced oxidation processes like WAO are valuable tools for addressing challenging
water treatment scenarios.
8
Chapter 5
AOP’s Description
5.1 Fenton
Fenton is considered to be one of the most effective advanced treatment processes in the
removal of many hazardous organic pollutants from refractory/toxic wastewater. It has many
advantages, but drawbacks are significant such as a strong acid environment, the cost of
reagents consumption, and the large production of ferric sludge, which limits Fenton’s further
application. The development of Fenton applications is mainly achieved by improving
oxidation efficiency and reducing sludge production. This chapter presents a review on
fundamentals and applications of conventional Fenton, leading advanced technologies in the
Fenton process, and reuse methods of iron containing sludge to synthetic and real wastewaters
are discussed. Finally, future trends and some guidelines for Fenton processes are given.
The presence of many organic pollutants in wastewater, surface water, and groundwater may
result from contaminated soil, agricultural runoff, industrial wastewater, and hazardous
compounds storage leakage. These organic pollutants, such as volatile phenols, benzene, and
benzene derivatives, are considered highly toxic and low biodegradable. In some instances,
conventional treatment methods such as biological processes are not sufficient to remove them.
In order to improve water quality, advanced treatment is needed to remove the refractory
organics.
Fenton is an effective advanced treatment process. The hydroxyl radical (·OH) can be
generated from the reaction between aqueous ferrous ions and hydrogen peroxide (H2O2), and
it can destroy refractory and toxic organic pollutants in wastewater. Fenton discovered the
Fenton reaction in 1894, and he reported that H2O2 could be activated by ferrous (Fe2+) salts
to oxidize tartaric acid. However, its application as an oxidizing process for destroying toxic
organics was achieved until the late 1960s. Fenton was mainly used to treat wastewater by
radical oxidation and flocculation. H2O2 is catalyzed by ferrous ions to decompose into HO·
and to trigger the production of other radicals, which can fully oxidize organic matters. The
hydroxyl radical (·OH) has a strong oxidation capacity (standard potential = 2.80 V versus
standard hydrogen electrode). Hydroxyl radicals can effectively oxidize refractory organic
pollutants in wastewater and even completely mineralized them into CO2, water, and inorganic
salts. Meanwhile, the iron complex produced in the treatment of wastewater by Fenton will
9
play the role of flocculant. The conventional Fenton continuous flow process configuration, as
illustrated in Figure 1, including acid regulation, catalyst mixing, oxidation reaction,
neutralization, and solid–liquid separation. Fenton has many advantages, such as its high
performance and simplicity (operated at room temperature and atmospheric pressure) for the
oxidation of organics and its non-toxicity (H2O2 can break down into environmentally safe
species like H2O and O2). However, Fenton also has some inherent disadvantages, which limit
its application
promotion. For example, strict pH range, high H2O2 consumption, and the accumulation of
disadvantages, the enhancement of the Fenton process has attracted much attention from
researchers. Both heterogeneous and homogeneous catalysts were used to replace Fe2+,
including ferric oxide, iron minerals, and nano zero-valent iron.
Fig 5.1 Schematic diagram of the Fenton process
5.2 Photo Fenton
The Fenton reaction is based on the use of a mixture of iron salts (Fe2þ) and H2O2, generating
HO radicals under mild acidic conditions Eq. The Fe2þ catalyst can be regenerated as shown
in Eq. or through reactions of Fe3þ with other intermediates (Bautista et al., 2008).
Fe2+H2O2→Fe3+OH-+HO
Fe3+H2O→Fe2+HO2+H+
10
Both Fenton and photo-Fenton processes have been found to be effective for the degradation
of pharmaceuticals. Despite having similar restrictions as the thermal Fenton process, the photo
Fenton reactions can be enhanced by UVeVis radiation to initiate additional HO radicals
(Andreozzi et al., 1999; Legrini et al., 1993). Solar photo-Fenton has been demonstrated for
the treatment of various pharmaceuticals such as antibiotics, anti-inflammatory, analgesic and
antineoplastic drugs (Alalm et al., 2015; Klamerth et al., 2010b; Sirtori et al., 2011; Trovo et
al., 2011 ). For example, Trovo et al. (2011) reported on the efficiency of photo-Fenton using
a solar simulator for the degradation of amoxicillin in the presence of two different iron species,
ferrioxalate complex and FeSO4. Complete removal of amoxicillin was achieved in the
presence of the ferrioxalate complex within 5 min, while 15 min were needed when FeSO4 was
applied in the presence of 120 mg/L H2O2. Nevertheless, the ferrioxalate complex was found
to demonstrate higher toxicity particularly for Daphia magna bioassays. Low concentrations of
Fe2þ (5 mg/L) and H2O2 (75 mg/L) have been shown to efficiently degrade 100 mg/L of loxacin
and trimethoprim under solar photo-Fenton conditions (Michael et al., 2012). Sirtori et al.
(2011) performed the solar photo-Fenton on nalidixic acid in different water matrices (i.e.
demineralized water, saline water and simulated
industrial effluent). The efficacy of the solar photo Fenton process was greatly affected by the
water composition, in particular for DOC removal. DOC removal from the simulated industrial
effluent was the lowest with 20% after 240 min, followed by 73% reduction in the saline water
after 107 min and 86% in the demineralized water after 92 min. Koltsakidou et al. (2017)
explored the solar photo-Fenton (Fe3þ/H2O2) degradation of 5fluorouracil by varying the
concentrations of H2O2 (0e90 mg/L) and Fe3þ (0e15 mg/L). At pH3, the optimum
concentrations of H2O2 and Fe3þ were 60 mg/L and 4.5 mg/L, respectively. This study chose a
lower concentration of Fe3þ, 4.5 mg/L, despite the higher concentration providing a slightly
higher degradation rate, due to the increased need for iron sludge removal if a higher
concentration were to be applied.
A recent study has reported that a ferrioxalate-based photo Fenton reaction using UVA-light
emitting diodes (LEDs) successfully led to complete degradation of antipyrine in 2.5 min, 93%
of TOC removal in 60 min and a reduction in the amount of H2O2 (Davididou et al., 2017). The
near monochromatic irradiation at 365 nm, which was close to the maximum absorbance of
the ferrioxalate complexes, was suggested to be the crucial factor (Davididou et al., 2017). A
minimal amount of H2O2 (100 mg/L) was found optimal to degrade 50 mg/L of antipyrine.
Excess H2O2 exhibited scavenger effects thus reducing the availability of HO radicals needed
for API degradation (Veloutsou et al., 2014). Although the Fenton process is not as energy
11
intensive as other
AOPs such as UV and O3, it requires low acidic pH (3e5) conditions (Malato et al., 2002) with
pH significantly influencing the Fenton reaction (Perini et al., 2018). At a pH higher
than 3, Fe3þ precipitates as Fe(OH)3, while at even higher pH values, the formation of Fe(II)
complexes leads to a decline in Fe2þ concentration. Much progress has been made in operating
Fenton and photo-Fenton processes at a neutral or near-neutral pH to deal with large-scale
operations or real wastewater samples (e.g. hospital wastewater) (GiraldoAguirre et al., 2017;
Perini et al., 2018). The removal of oxacillin was performed at pH~6 (Giraldo-Aguirre et
al., 2017), while the removal of mixtures of micropollutants by means of photo-Fenton was
performed at pH 6e7 (De la Cruz et al., 2013b). A 203 mmol/L solution of oxacillin was
completely eliminated after 50 min in the presence of 90 mmol/L of Fe2þ, 10 mmol/L of H2O2
and irradiation with a 30 W light source (365 nm) at pH 6 (Giraldo-Aguirre et al., 2017). The
potential use of iron ligands or complexing agents such as oxalate, citric acid
and
ethylenediaminedisuccinic acid has been investigated when performing photo-Fenton
reactions at a neutral pH (Klmerth et al., 2010a; Miralles-Cuevas et al., 2014).In addition to
working at non-conventional pHs, different sources of iron species have also been investigated
to compare their effects on the degradation efficiency of APIs. de Lima Perini et al. (2013)
investigated the potential of iron citrate, iron oxalate, and iron nitrate on the conversion of
ciprofloxacin. Iron citrate and iron oxalate resulted in the highest conversion of ciprofloxacin
(25 mg/ L) at pH 4.5, but iron citrate was superior based on the highest TOC removal (0.699).
A low reactivity between iron nitrate and H2O2 was suggested to be the cause of the poor
degradation of ciprofloxacin.
Overall, researchers are constantly investigating approaches to overcome the low acidic
condition requirements of Fenton and photo-Fenton reactions. By modifying ‘conventional
‘conditions, a better insight in the efficiency is obtained and sluggish degradation kinetics are
overcome. However, more studies need to be performed and optimized at a wide pH range
using natural and wastewater
5.3. Ozonation
Involving O3 in aqueous reactions may produce various unwanted byproducts due to its high
redox potential. The two pathways that may occur are direct and indirect reactions, with the
former being preferable. The two different half-reactions that may occur in water are:
12
O3 + 2H+ + 2e− → O2 + H2O
O3 + H2O + e− → O2 + 2HO−
Usually, ozone is utilized to break C=C bonds in organic compounds. In its indirect reactions,
it creates different radicals depending on the pH values.
O3 + OH− → HO•2+ O2•− (1 < pH < 7)
O3 + OH− → HO•2+ O2 (8 < pH < 14)
O3 + HO•2→ HO•2+ O3•−
Under alkaline conditions, HO•2 is highly unstable, propagating reactions such as those
detailed below :
HO•2→ O2•− + H+
O3 + O2•− → O3•− + O2
O3•− + H+ → HO•3
HO•3→ •OH + O2
O3 + •OH → HO•4
HO•4+ HO•2+ O2
HO4 radicals ultimately produce more HO2 radicals, creating OH radicals for the AOP. The
most significant problem with such systems is the control of ozone byproducts such as bromate
and N-nitrosodimethylamine, which are both carcinogenic. These also raise issues in the
biological stability of the outcomes of the AOP, because acids, aldehydes and degradable
organic compounds are produced. Two major categorizations are included in these O3-based
processes: ozone/hydrogen peroxide and ozone/UV. The former is favored in general
wastewater treatments because the production of hydroxyl radicals is enhanced through the
dissociation of H2O2 , whereas in the latter, UV radiation photolyzes O3 to the production of
H2O2; in turn, this product produces the necessary OH radicals], as expressed below:
O3 + H2O + hv → H2O2
H2O2 + hv → 2 •OH
Ozone/hydrogen peroxide has been already implicated in the pharmaceutical sector, as stated
13
by Almomanietal. [74]. The oxidation of various antibiotics, estrogens, etc., has been
monitored, and the parameters for higher yields are mainly the concentrations, directly
increasing the rates of the oxidation reactions. A fully controlled double-sided glass reactor
was operated in semi batch modes, with proper mass flow controllers, washing traps, a diffuser,
and pH and temperature controls. An effluent-rich ozone/hydrogen peroxide catalyst was also
tested for anticancer, antipsychotic and painkiller drugs. A COD reduction was achieved,
reaching 88% in a pH range of 4~6. A custom-made assembly with a glass reactor supported
by ozone and oxygen generator systems with controllable flows was used for the experiments,
with 200 mL of wastewater in each batch run [75]. Finally, lake water and wastewater samples
were treated with ozone/hydrogen peroxide AOPs, in a batch reactor500 mL at pH = 8,
resulting in the increased transformation of atrazine (ATR), sulfamethoxazole (SMX) and Nnitroso-dimethylamine (NDMA), whilst keeping the bromate formation at a percentage of 70%
Ozone-based processes produce the strongest oxidants in large quantities due to the O3 splitting
reaction. Byproducts are more biologically stable but lead to the formation of aldehydes such
as formaldehyde, which is a genotoxic compound. Although it has a powerful oxidation
capability, there are some drawbacks to its use in aqueous reactions, due to its low solubility
in water. The mass transfer of gas–liquid interfaces and self-decomposition are the limiting
steps for water purification systems. Generally, this AOP is used as a pretreatment step in
wastewater treatment, with no suggestions in major water purification procedures
5.4. Sonolysis
Ultrasounds in aqueous medium constitute a particular AOP technology which can proceed through
two distinct types of actions, either a chemical (indirect) or a physical (direct) mechanism. In the
indirect action, generally realized at high frequency, water and dioxygen molecules undergo hemolytic
fragmentation and yield •OH, HO2•, and •O radicals (Riez et al.,1985; Lorimer and Mason, 1987;
Trabelsi et al., 1996; Zaviska et al., 2009).The direct action, so-called sonication, involves the formation
by the ultra-sounds of cavitation bubbles which grow, then collapse, creating powerful breaking forces
with extremely high temperatures (T = 2000–5000 K) and pressures (about 6 × 104 kPa). In these
extreme conditions, a sonolysis of water molecules occurs, which produces very reactive radicals able
to react with organic chemical species present in the aqueous medium and and/or a pyrolysis
degradation of organic compounds is taking place
H2O +))) → •OH +• H (22)
•OH + X (O.C.) → Products (23)
X (O.C.) + H → Products (24)
14
where: ))) = ultrasound, X(O.C.) = organic compound(s). Therefore, in recent years, ultrasounds have
been widely used for the oxidation and degradation/destruction of organic pollutants in waters,
wastewaters, and sewage sludges, as shown in several studies (Naffrechoux et al.,2003; Minero et al.,
2005; Dai et al., 2006; Ku et al., 2006; Kim and Huang, 2007; Torres et al., 2007; Sun et al., 2007; Qiu
et al., 2008; Ghodbane and Hamdaoui, 2009; Zaviska et al., 2009; Ma, 2012). However, a notable
drawback of the water treatment by ultrasounds is that the number of generated •OH radicals is
generally insufficient. Consequently, ultrasounds have been more often applied in the presence of other
oxidants, such as H2O2 and dioxygen, as well as in combination with UV irradiation and with various
AOPs, including the Fenton’s reagent (with different forms of iron: Fe0 , Fe2+,and Fe3+) and Fentontype reactions. The later combined methods are generally called sono-Fenton AOPs. In these
conditions, the development of such advanced hybrid techniques has resulted in the improvement of
the degradation/destruction efficiency of organic pollutants in waters and of the reduction of the
sonochemical treatment time (Trabelsi et al., 1996; Naffre- choux et al., 2003; Minero et al., 2005; Dai
et al., 2006; Liang et al., 2007; Sunet al., 2007; Torres et al., 2007; Namkung et al., 2008; Oturan et al.,
2008b;Qiu et al., 2008; Ghodbane and Hamdaoui, 2009; Joseph et al., 2009; Maet al., 2010; Ma and
Sung, 2010; Ma, 2012), although a clear understanding of the theory and mechanisms of these various
sonochemical hybrid AOP techniques needs to be done
As pointed out and described in detail in the very recent review of Ma(2012), several important,
operational parameters, including the ultrasonic frequency (range: 20–1700 kHz) and amplitude, the
iron type (Fe0 , Fe2+, and Fe3+) and dosage, and the solution pH, must be optimized in order to improve
the efficiency of the sonochemical AOP treatment of polluted waters. Moreover, it has been also shown
that the optimal values of ultrasonic frequency and amplitude depended on the characteristics of the
effluents to be treated (nature and concentration of pollutants . . . ) as well as on the experimental
conditions (type and volume of the sonochemical reactor, treatment time . . . ), and that the
physicochemical properties of effluents (vapor pressure, surface tension, viscosity, presence of
impurities and/or gas . . . ) had a significant effect on the performances of the sonochemical reactor
(Gogate and Pandit, 2000, 2001, 2004; Zaviska et al., 2009).
In fact, during the last decade, the sonochemical AOPs have been broadly applied to the
degradation/destruction of a great variety of pollutants, including pesticides (Oturan et al., 2008a; Ma
et al., 2010; Ma and Sung, 2010), dyes (Minero et al., 2005; Sun et al., 2007; Ghodbane and Hamdaoui, 2009; Ma, 2012), aromatic compounds (Trabelsi et al., 1996; Petrier et al., 1999; Dai et al., 2006;
Ku et al., 2006; Liang et al., 2007; Namkung et al., 2008; Ma, 2012), endocrine disrupters (bisphenol
A) and pharmaceuticals (Torres et al., 2007; Ma, 2012), and disinfectant by-products (Kim and Huang,
2007) in waters and/or wastewaters.
15
Although the combination of ultrasounds with the Fenton-type reactions has resulted into the rapid and
recent development of sonochemical methods for the removal of organic pollutants from waters, and
seems able to lead to a very promising technologic approach for decontamination purposes, most
experimental works have been performed until now at the laboratory scale in artificial systems, with
only one or two compounds as the model contaminants (Ma, 2012). , application of sonochemical AOPs
at the industrial level in a real-time water (or wastewater) treatment plant would be needed to
demonstrate the economic and commercial feasibility of these methods.
Fig.5.4 Sonolysis process
5.5. UV based
Generally, the presence of UV light radiation, if properly combined with hydrogen peroxide, may
effectively produce OH radicals; simultaneously, UV light acts as a natural disinfectant agent for many
organic pollutants and wastewater systems. The applications of such systems have been reported in
many fields, varying from the pharmaceutical sec- tor to the pharmaceutical industry, organic pollutant
removal. The chemistry of this procedure has been investigated by modeling the mechanisms and
processes, concluding that the substitution of expensive H2O2 with other chemicals, such as Cl2, may
be a useful alternative and excellent candidate at low pH values and low UV doses. The main chemical
16
reaction occurring in such systems is described below:
H2O2 + hv → 2•OH
……. (1)
Through the effect of radiation, the hydrogen peroxide molecules form OH radicals. This decomposition is attributed to a Haber–Weiss mechanism, which is initiated by cleavage of
the O–O bond. Further chemical OH production is initiated by the following reactions [40]:
H2O2 + •OH → H2O + HO•2
……… (2)
H2O2 + HO•2 → H2O + O2 +•OH
…… (3)
However, in some cases, radical recombination occurs, as follows [41]:
•OH + HO• → H2O2
………… (4)
•OH + HO•2 → H2O + O2 ..........(5)
HO•2 + HO•2 → H2O2 + O2 ……… (6)
Many factors affect the efficiency of the above reactions, such as the concentration of hydrogen
peroxide, the source of UV radiation and the physicochemical characteristics of fluid involved in the
oxidation process. In Figure 1, the effect of the H2O2 concentration is indicative of the degradation of
carbamazepine.
Equations are used by different groups to describe the synergistic utilization of UV radiation and
H2O2. For example, Verma et al. described the combination of UV-C radiation and H2O2 for the
successful degradation of the toxic anatoxin-a, suggesting the alternative effect of the harsher UV-C
radiation instead of UV-A. Anatoxin-A is extremely toxic; therefore, the experiments were conducted
in Lamil Plus Class II micro- biological safety cabinets (Karstulan Metalli Tek-Fin Oy, Finland). The
UV radiation was produced by DUV LEDs (TO39FW), developed by Sensor Electronic Technology,
Columbia. Bagheri et al. tried to overcome the excess recombination using only vacuum-UV
processes, emphasizing the effect of fluid concentrations. A prototype annular photoreactor made of
Plexiglas was photo-assisted by mercury 42 W amalgam lamps; all these experiments were conducted
under continuous flow. These parameters were also investigated by Crapulli et al. for mechanistic
modelling, combining different concentrations and UV radiation wavelengths in order to estimate the
higher penetration depths of hydroxyl radicals (•OH). Their concentration profiles were gathered
under air- and oxygen-saturated conditions corresponding to Re = 1587 over a period of 60 min in a
vacuum-UV reactor with cooling capabilities maintaining constant power concluded that UV
radiation with an alternative medium, such as O3, is more effective than H2O2. All experiments were
performed in
17
custom-made laboratory-scale reactors, under a UV lamp with nominal power ranging from 11 to 60
W and volume reactor capacities from 0.1 to 3.1 L. Their reactor setup included a glass tank, a pump
and a stainless-steal irradiation reactor tube holding the UV lamp. Nevertheless, the main asset from
this AOP is the strong synergy of the photolytic dissociation of H2O2, along with photolytic activity
Especially in the pharmaceutical industry, decomposition of the products requires the energy of this
AOP in order to achieve maximum efficiency of the reaction
5.6. Wet Air Oxidation
The wastewater containing organic pollutants, such as pharmaceutical residues, is collected and
prepared for treatment. This may involve pre-treatment steps to remove solids, adjust pH, or dilute the
wastewater to optimal conditions for the WAO process. The prepared wastewater is pressurized to the
desired operating pressure typically ranging from 5 to 200 bar. Pressurization increases the solubility
of oxygen in water, facilitating the oxidation reactions: The pressurized wastewater is then heated to
the desired operating temperature, typically between 150°C and 320°C. Heating promotes the rapid
oxidation of organic compounds by increasing their reactivity with oxygen.: In the reaction vessel, the
hot, pressurized wastewater comes into contact with oxygen, either supplied from an external source or
generated in situ by decomposing oxygen-containing compounds in the wastewater.
The oxidation reactions occur, breaking down the organic pollutants into simpler, less harmful byproducts.: After the oxidation reaction, the treated wastewater is cooled to lower temperatures to
facilitate subsequent handling and processing. Cooling may involve passing the wastewater through a
heat exchanger or other cooling devices.: Any remaining solids or suspended particles are separated
from the treated wastewater through processes such as settling, filtration, or centrifugation. This step
helps to clarify the wastewater before further treatment or discharge. If necessary, any by-products or
residual contaminants generated during the WAO process are further treated or disposed of according
to environmental regulations. and: Depending on the specific requirements and regulations, the treated
wastewater may be recycled for reuse within the pharmaceutical facility or discharged into the
environment after meeting relevant discharge standards.
18
Fig. 5.6 Wet Air Oxidation Process
5.7 Adsorption
Adsorption process is exothermic and spontaneous in nature. The adsorption of direct blue 106 dye
increased, when the adsorbent increased, low temperature and reduce in initial dye concentration. The
adsorption findings confirmed pseudo-second order and intra particle diffusion. Palm ash was used to
prepare low cost activated carbon Adsorption of blue 71 dye confirmed the Freundlich model in the
range of 50 - 600 mg/L. The kinetic data fitted well with pseudo-second order model. Almond shell has
been employed to prepare activated carbon The percentage of removal of direct red 80 dye about 97 %
after 1 hour. Adsorption process supported pseudo-second order kinetic and Langmuir model. Orange
peel was used to synthesis activated carbon. Adsorption data revealed that removal of direct navy blue
106 dye is physical process, fitted well to Freundlich model. This work confirmed pseudo-second order
kinetic with intraparticle diffusion process.
Characteristics of acid dyes including anionic, were used for wool, food colorants and medical
industries at acidic conditions. Several examples of acid dyes such as acid blue 83, acid black 1, acid
orange 7, acid blue 1 and acid yellow 36. Hazalnut bagasses were used to prepare activated carbon at
600˚C by using zinc chloride as activating agent. Absorbent has surface area of 1489 m2/g. Adsorption
capacities increased at lower pH, higher concentration of dye (acid blue 350) and higher temperature.
Based on the experiment results, the highest adsorption capacity about 450 mg/g, at 45˚C, pH 2.
Activated carbon has been prepared by using different raw materials. Experimental results showed that
activated carbon could be used as adsorbent to remove dye from wastewater on a laboratory scale.
Various types of dyes such as vat dye, basic dye, acid dye, direct dye, reactive dye and disperse dye
were successfully removed from effluents. The percentage removal of dye depended on experimental
19
conditions. In future, more and more researchers focus on the design and operational experiences with
pilot plant testing of activated carbon adsorption system.
Fig.5.7 Adsorption
20
Chapter 6
6.1 Comparison of various AOP methods.
Sr.No Types of
(AOP)
1.
2.
3.
4.
5.
6.
Remark (Parameter)
Advantages
Dis-Advantages
effective for
degrading organic
pollutants, operates
ambient temperature
and pressive Suitable
for continuous
treatment.
Effective for the degradation of a wide
range of pollutant
relatively low
cost,can operate under
mild condition
Low catalyst conc,
Renewable energy,
high degradation rate
High energy input,
limited applicable to
certain waste - water
compositions
Potential scaling
issue.
Rapid degradation of
pollutants, versatile
for various types of
waste water, minimal
chemical usages.
Energy -intensive
effectiveness
influenced by waste
water composition
and UV
transmittance by
product.
Efficient for the
degradation of wides
range of
pharmaceutical
compound
disinfection
properties minimal
sludge production.
High energy
consumption limited
effectiveness, for
certain compound
potential
generation of harmful
By- product.
Wet air oxidation
Palladium High degradation
(WAO) involves the
Cobalt
efficiency effective
oxidation of organic
for recalcitrant
pollutant in the
Compound can
presence of oxygen and
handle
elevated temperature
High organic loads.
(typically above 150°c)
and pressure.
High energy
Consumption
equipment potential
formation of nitrogen
Oxides and other byproduct.
Sonolysis involves the
use of ultrasound waves
to generate cavitation
bubble in the waste
water, which leads to
the formation of
hydroxyl radicals.
Fenton
Fenton’s reagent
involves the addition of
iron salts (Fest or Fe3+)
and hydron peroxide
(H2O2) to the waste
water
Photo
Photo-Fenton combines
Fenton
Fenton’s reagent with
UV or sunlight
imitation
UVUV-Based Apo’s
Based
involves the use of
ultraviolent (UV) light
in combination with
oxidants such as
hydrogen peroxide
(UV/H2O2) or Ozone
(UV/03).
Ozonation Ozonation typically
requires the presence of
Ozone gas, suitable PH
(Usually neutral to
slightly alkaline)
And appropriate
contact time for
effective degradation.
Catalyst
used in
process
Sonolysis
Wet air
oxidation
------
Fe2&fe3
Fe2&fe3
may be
used
03
----
21
PH adjustment
require for Fenton
reagent, potential
formation of sludge
dependency on UV
source for Fenton.
Acidic pH,high operating costs,inhibition
by radical scavengers
Chapter 7
Advantages and Application
7.1 Advantages of AOP
•
Rapid reaction rates
•
Small foot print
•
Potential to reduce toxicity of organic compounds
•
Mineralization of organics, i.e. conversion to salt and CO2
•
Does not concentrate waste for further treatment, such as membranes
•
Does not produce “spent carbon” such activated carbon absorption
•
Easily automated and controlled.
7.2 Application
•
AOPs have been extensively explored for efficient
degradation from various aqueous matrices.
•
The process based on the generation reactive species of
hydroxyl ion (OH.) radicals with high oxidized power
•
The radical species oxidize the complex molecules into
smaller fragments
•
AOPs commonly used for the degradation of Dye waste
Include ozone based, UV based, Fenton based, Adsoprtion
based.
•
They exhibit high degradation efficiency, rapid degradation
rate and ecofriendly characteristics.
22
Chapter 8
Future work
•
To Perform the Experimental Work
•
To Prepare the textile wastewater from the available textile dyes
•
To investigate the quality of the water after the filtration using the prepared ozonation
process.
•
To compare the results with other water treatment methods
Future work are the actions or suggestions that you propose to overcome or mitigate these
limitations, such as conducting more experiments, collecting more data, using different
methods, or exploring new hypotheses.
Additionally, we will work on improving the Adsorption processes. We want to find the best
conditions for these processes to be most effective. Our main goal is to figure out the best ways
to combine these different processes. By trying out different combinations, we hope to find the
most effective way to break down the substances we're studying.
23
References
1. Siti Zuraida, M.1 , Nurhaslina,C.R.2 , Ku Halim Ku Hamid2, 2319-183X, (Print)
2319 1821 Volume 2, Issue 5(May 2013), PP.01-07 …. this work showed that bacteria
species, Lactobacillus delbruckii possessed impressive decolorization efficiency.
2. Sobhan Ghanbari1,2 · Ali Fatehizadeh1,3 · Mehdi Khiadani Ensiyeh Taheri1,3
Hafz M. N. Iqbal5….. study demonstrates the efficacy and feasibility of dye removal in
real textile wastewater using UV/Chlorine/Br process followed by activated carbon
adsorption.
3. Zarafshan Ali 1 , Amir Ikhlaq 1,* , Umair Yaqub Qazi 2,* , Asia Akram 3 , Iftikhar
Ul-Hasan 4 , Amira Alazmi 5 , Fei Qi 6 and Rahat Javaid 7,* This study compared the
efficiencies of the ozonation and catalytic ozonation processes for the removal
ofdisperse yellow 42 dye from an aqueous solution.
4. Mehrangiz Pourgholi 1 , Reza Masoomi Jahandizi 2* , Mohammadbagher Miranzadeh,
Ommolbanin Hassan Beigi 1 , Samaneh Dehghan.
The results of this research showed that dye removal using AOP has impact and COD based
5. Zahid Mehmood a , Hafsa Khurshid a , Zanib Khurshid b , Muhammad Aamir a
Mehwish Khan a Vol 5, no 2, pp 2955-2968 February 2024….dye-containing
wastewater, poses significant environmental issues Photocatalysis has proven efficient
approach for dye degradation in wastewater treatment operations
6. Anna Lanzetta 1 , Stefano Papirio 1 , Armando Oliva 1 , Alessandra Cesaro 1,* , Luca
Pucci 2 , Emanuele Mariano Capasso 2 , Giovanni Esposito 1 and Francesco Pirozzi 1
7. R. F. Momin1 , P. B. Patil2 , S. Raut Jadhav3,(IJRASET), Volume 5 Issue VI, June
2017.
In the present study, degradation of Acid Blue 80 (AB80) was carried out by
Using Ultrasound Cavitation.
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