J Water Process Engineering 2024, 58, 104838 Advancing pharma wastewater treatment - Review of catalytic reactor-based hybrid approaches

Journal of Water Process Engineering 58 (2024) 104838
Available online 2 February 2024
2214-7144/© 2024 Elsevier Ltd. All rights reserved.
Advancing pharmaceutical wastewater treatment: A comprehensive review
on application of catalytic membrane reactor-based hybrid approaches
Ramesh Kumar
a , 1
, Elinah Awino
b , 1
, Dorcas Wanja Njeri
b , 1
, Aradhana Basu
c
, Sujoy Chattaraj
d
,
Jayato Nayak
e
, Snehagni Roy
b
, Gausal A. Khan
f
, Byong Hun Jeon
a , *
, Alak Kumar Ghosh
g
,
Shrabana Pal
h
, Shirsendu Banerjee
b
, Prabhat Rout
i
, Sankha Chakrabortty
b , *
, Suraj K. Tripathy
b
a
Department of Earth Resources & Environmental Engineering, Hanyang University, 222-Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
b
School of Chemical Technology, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, India
c
School of Sustainability, XIM University, Bhubaneswar 752050, India
d
Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
e
Centre for Life Science, Mahindra University, Hyderabad, Telangana, India
f
Department of Clinical Nutrition, College of Applied Medical Sciences, King Faisal University, Al Ahsa, Saudi Arabia
g
Department of Chemistry, The University of Burdwan, Burdwan (E) 713104, West Bengal, India
h
Department of Pharmacology, IPGME & R, SSKM Hospital, Kolkata 700020, India
i
School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, India
ARTICLE INFO
Editor: Andrea Merenda
Keywords:
Pharmaceutical wastewater
Membrane catalytic reactors
Advanced oxidation systems
Antibiotics removal
Water treatment
ABSTRACT
Pharmaceutical wastewater presents a concerning array of toxic chemicals, necessitating proper treatment and
disposal to safeguard human health and the environment. These chemicals, including active pharmaceutical
ingredients, antibiotics, solvents, and organic compounds, exhibit toxicity, ammability, and carcinogenicity,
posing risks to living beings and ecosystems. Contaminants such as surfactants, emulsiers, residual drugs, and
metabolites further exacerbate the complexity of pharmaceutical wastewater. Conventional treatment technol-
ogies, such as activated carbon adsorption, oxidation processes, membrane ltration, and biological treatment,
suffer limitations in effectively removal or neutralizing hazardous substances for the safe disposal of pharma-
ceutical wastewater if implemented individually. In particular, combining photocatalysis with membrane tech-
nology demonstrates promising benets, enhancing degradation efciency and reducing membrane fouling.
Membrane catalytic reactors (MCRs) integrated with advanced oxidation systems, viz. photocatalysis, Fenton-
based processes, ozonation, persulphate generation, and the electrocatalytic process, can degrade pollutants
and realize their physical separation. The present review manuscript comprehensively discusses detailed
mechanisms, performance, inuencing factors, and generation of catalytic radicals for removing organic pol-
lutants in hybrid MCRs to improve water quality and safeguard ecosystems from wastewater.
Abbreviations: APAP, acetaminophen; ACF, activated carbon ber; AOPs, advanced oxidation processes; AMP, ampicillin; AnMBR, anaerobic membrane bio-
reactors; AQY, apparent quantum yield; AZM, azithromycin; BF-MBR, biolm membrane bioreactor; BOD, biological oxygen demand; BDD, boron-doped diamond;
CF, carbon ber; CQDs, carbon quantum dots; CMs, catalytic membranes; CBZ, carbamazepine; CEX, cephalexin; CMF, ceramic membrane ltration; COC, chemical
oxygen concentration; COD, chemical oxygen demand; CAP, chloramphenicol; CIP, ciprooxacin; CT, contactor-type; DT, distributor-type; DOX, doxycycline; EFCM,
electro-Fenton catalytic membrane; EF, electro-Fenton; EO, electro-oxidation; EDUF, electrodialysis and ultraltration; ED, electrodialysis; EE/O, energy per unit
order; ET, extractor-type; FBR, uidized-bed Fenton; FO, forward osmosis; GPMs, geopolymeric membranes; HRT, hydraulic retention time; MMW, magnetic mining
waste; MBR, membrane-incorporated bioreactors; MCRs, membrane catalytic reactors; MOF, metal-organic framework; MF, microltration; MICM, molecularly
imprinted catalytic membrane; NF, nanoltration; OFL, ooxacin; OTC, oxytetracycline; PS, peroxydisulfate; PMS, peroxymonosulfate; PhACs, pharmaceutically
active compounds; PEC, photo-electrocatalytic; PM, photocatalytic membrane; PMR, photocatalytic membrane reactor; PNF, photocatalytic nanoltration; POF,
photocatalytic optical bers; PSf, polysulfone; PVDF, polyvinylidene uoride; QY, quantum yield; RO, reverse osmosis; SRT, solid retention time; SDZ, sulfadiazine;
SMZ, sulfamethoxazole; TCH, tetracycline hydrochloride; TC, tetracycline; ZTM-T, Ti-based catalytic membranes; TiO
2
-HAP, titanium dioxide-doped hydroxyapatite;
TDS, total dissolved solid; TOC, total organic carbon; TMP, trimethoprim; UF, ultraltration; UV, ultraviolet; ZO, zinc oxide.
* Corresponding authors.
E-mail addresses: [email protected] (B.H. Jeon), [email protected] (S. Chakrabortty).
1
Authors have equal contributions.
Contents lists available at ScienceDirect
Journal of Water Process Engineering
journal homepage: www.elsevier.com/locate/jwpe
https://doi.org/10.1016/j.jwpe.2024.104838
Received 14 September 2023; Received in revised form 10 January 2024; Accepted 14 January 2024

Journal of Water Process Engineering 58 (2024) 104838
2
1. Introduction
The pharmaceutical industry has rapidly grown over the past two
decades, becoming a global economic powerhouse. Recent research re-
veals that global antibiotic consumption reached 40.1 billion dened
daily doses in 2018. In the pharmaceutical industry, water serves mul-
tiple purposes, such as raw materials, components, and solvents in
formulating, producing, and processing pharmaceutical products [1].
About 23 % of the water supply is estimated to go towards its operation,
which results in the generation of highly toxic and contaminated
wastewater that demands costly, multistage treatment to meet regula-
tory requirements [2]. Pharmaceutical wastewater has a high concen-
tration of ammonia‑nitrogen, chroma, organic material, and nutrients. It
exhibits elevated levels of chemical oxygen demand (COD), biological
oxygen demand (BOD), and chemical oxygen concentration (COC).
Reports indicate that nearly 200 pharmaceutically active compounds
(PhACs) have been found in various water sources, from wastewater to
surface water to groundwater [3]. Conventional wastewater treatment
plants (WWTPs) are not designed to degrade emerging pollutants like
PhACs. Studies have found high concentrations of antibiotics, such as
cephalexin (CEX), azithromycin (AZM), and ciprooxacin (CIP), in
treatment plant efuents [4]. Several methods, such as activated sludge
[5], anaerobic treatment [6], constructed wetlands [7], adsorption [8],
coagulation/occulation [9], membrane [10], and ozone/hydrogen
peroxide treatment integrated technology [11], were explored for
pharmaceutical wastewater treatment. However, conventional waste-
water treatment processes are not designed to degrade emerging phar-
maceutical pollutants.
Recently, membrane technology has become increasingly popular for
large-scale water treatment systems, especially in developed countries
[12]. Basically, a membrane is a semi-permeable barrier, allowing some
substances from the source uids to pass through while selectively
preventing others. Contaminant separation is dependent on attributes
like charge and size [13]. However, membrane clogging and fouling due
to the deposition of solutes over the membrane surface or gel layer
formation by concentration polarization near pores have resulted in
permeability loss, which depends upon the module type (crossow or
dead-end), membrane materials, applied pressure, and crossow rate
[14]. Such intervention is time-consuming, chemical-intensive, labor-
intensive, and possibly destructive to membranes, all of which have a
bigger impact on costs. Catalytic membranes (CMs) can be applied to
drive a continuous treatment process, generating reclaimable treated
water. Catalytic properties can be integrated onto and throughout the
surface of the membrane, introducing an advanced technology for
wastewater treatment referred to as membrane catalytic reactors
(MCRs). CMs have a dual role, as they anchor the catalyst on their
surface or embed it within their structure. This dual function combines
ltration and catalysis capabilities, allowing simultaneous pollutant
oxidation to maintain membrane cleanliness and delay membrane
fouling, enabling easy catalyst reapplication and enhancing the process
intensication approach [15,16]. It integrates membrane separation
with catalytic reactions within a singular unit, resulting in increased
conversion rates, enhanced selectivity, and a more streamlined, cost-
efcient reactor design that can serve the gaps in conventional treat-
ment processes [17].
Lu et al. synthesized a catalytic nanobrous membrane known as
Co
x
O
y
@carbon catalytic nanobrous membrane (Co
x
O
y
@CCNM) by
facilitating the in-situ growth and subsequent pyrolysis of ZIF-67 on the
nanobers [18]. This membrane enables rapid, durable, and continuous
degradation of antibiotic compounds such as tetracycline (TC), CIP, and
sulfamethoxazole (SMZ) through a gravity-driven ow-through ltra-
tion process. The novel ZIF-67-derivative-functionalized Ti-based CMs
(ZTM-T) demonstrated exceptional efciency in removing SMX, reach-
ing an impressive removal rate of 96.3 %. This level of removal was
signicantly higher, 216.7 times greater than membrane ltration alone
and 3.8 times higher than peroxymonosulfate (PMS) treatment alone. In
addition, a potential mechanism for the degradation of SMX was
investigated using a combination of density functional theory analysis
and high-performance liquid chromatography-mass spectrometry [19].
MCRs may contain conductive or chemically active components, i.e.,
external stimuli such as light, electrical current, chemical activation,
enzymatic response, or any combination of these, which can boost the
concentration and destruction of the contaminants [20].
Here, several emerging technologies, starting from membrane-based
separation and membrane bioreactors, various AOPs, and advanced
MCRs, are critically evaluated for continuous treatment to enhance the
scale-up condence from lab-to-pilot-to-industry. A paradigm shift is
necessary to tackle the quick-changing scenario on real eld scenarios
for treating complex pharmaceutical wastewater by developing novel
MCR-based technology. Membrane-based emerging technologies help to
transform the existing wastewater treatment plant technologically faster
and more efciently for the removal of PhACs. This holistic approach
addresses the long-term sustainability of urban water systems, with
“blue” representing freshwater supplies, “green” representing environ-
mentally friendly technologies, and “grey” representing wastewater
purication. These systems can enhance water quality and protect
ecosystems by eliminating organic contaminants, heavy metals, and
pharmaceuticals from wastewater through the combined power of
photocatalysis and membrane separation.
The current review manuscript has conducted an extensive literature
survey on essential aspects, such as composition variation in pharma-
ceutical wastewater and innovation in treatment processes, especially in
advanced oxidation processes (AOPs). The novel content in the present
review paper compared to the existing literature on pharmaceutical
wastewater treatment over the last ve years is mentioned in Table 1.
Most of the review manuscripts focused on general technological ad-
vancements [21,22] or the hybrid treatment process that includes con-
ventional and emerging technologies, such as adsorption followed by
electrochemical oxidation [23], combined biological, membrane, and
ultrasonication [24], AOPs integrated with nanocatalyst [25], AOP with
immobilized photocatalysts on carbon nanotubes [26], and integration
of photocatalysis and membrane separation technology [27]. The
membrane separation technology is considered a promising method for
the separation of solid from liquid [28,29], which can be utilized as a
suitable carrier for novel and effective nanoscale photocatalytic material
for the simultaneous degradation of PhACs and permeation of treated
water in a continuous way.
2. Pharmaceutical wastewater: an overview
Water, a vital component in pharmaceutical production, is a raw
material in producing different pharmaceutical products, active phar-
maceutical ingredients, formulations, analytical reagents, and
compendia articles. This necessitates a reliable supply of clean water for
the industry [1,36]. The pharmaceutical industry is extremely water-
dependent, resulting in numerous wastewater-generating processes.
The sheer volume and composition of wastewater in the pharmaceutical
industry vary by operation and production rate, with no standard
wastewater composition due to the heterogeneity of drugs used. The
efuent is highly toxic and dangerous to the biota and has an intense
hue. Non-biodegradable organic matter such as antibiotics, animal and
plant steroids, analgesics, beta-lactamides, reproductive hormones, and
metals, such as chromium, cadmium, mercury, lead, and nickel, are
found in large quantities in pharmaceutical wastewater [37]. The Cen-
tral Pollution Control Board of India regulates the release of such haz-
ardous waste into the environment. Efuent discharge restrictions for
the selected countries are shown in Table 2. Multiple studies have used
pharmaceutical wastewater to classify pharmaceutical wastewater by
using pH measures, total dissolved solids (TDS), BOD, COD, biode-
gradability, alkalinity, and ammonia‑nitrogen concentration. While
characterizing pharmaceutical wastewater in India, Damodhar and
Reddy found that the River Uppanar had TDS levels ranging from 354.38
R. Kumar et al.

Journal of Water Process Engineering 58 (2024) 104838
3
Table 1
Comparative evaluation review articles published over the last ve years on antibiotics removal methods during pharmaceutical wastewater remediation.
References Critical points
discussed in the
selected review articles
(Highlights and
strengths)
Review coverage relevant to antibiotic removals during pharmaceutical wastewater treatment system
Target pollutants General wastewater
composition
Membrane-based treatment process Advanced oxidation processes (AOPs) Catalytic
membrane
reactor
Separate
membrane process
Membrane-
incorporated
bioreactor
Photo/Fenton
oxidation
process
Electrochemical
oxidation
Ozonation Photocatalysis
process
[23] - Discussed adsorption,
electro-sorption, and
electrochemical
oxidation methods
for pharmaceutical
wastewater
treatment
- Highlighted reaction
mechanisms and
optimization of
operating parameters
- General
pharmaceutical
wastewater
- Not covered - Not covered - Not covered - Not covered - Covered - Not covered - Not covered - Not covered
[30] - Discussed AOPs for
general hospital
efuent wastewater
treatment
- Critically evaluated
individual AOPs
- Discussed the AOPs
potential on real
wastewater matrices
for remediation
- General hospital
efuents
discussed as
pharmaceutical
wastewater
- Discussed hospital
efuent
composition
- Not covered - Briey
covered
- Covered - Covered - Covered - Covered - Not covered
[21] - Discussed recent
advancements in
various technologies
for pharmaceutical
wastewater
treatment
- Reviewed about
microbial fuel cells,
bio-nanotechnology,
and bioltration
- Discussed about
challenges and
recommendations for
pharmaceutical
wastewater
treatment
- General
pharmaceutical
wastewater
- Discussed about
pollutant sources
in pharmaceutical
wastewater
- Not covered - Not covered - Not covered - Not covered - Not covered - Not covered - Not covered
[22] - Discussed the
removal efciency
and operating
parameters of
pharmaceutical
wastewater
treatment methods
(adsorption, Algal
bioremediation,
constructed wetland,
and coagulation/
occulation)
- Wastewater
containing non-
steroidal anti-in-
ammatory
drugs (diclofenac
and naproxen)
are discussed
- Not covered - Briey discussed
ultraltration
(UF) membrane
application as a
hybrid
technology
- Briey
discussed as
hybrid
technology
- Not covered - Not covered - Briey
discussed as
hybrid
technology
- Not covered - Not covered
(continued on next page)
R. Kumar et al.

Journal of Water Process Engineering 58 (2024) 104838
4
Table 1 (continued )
References Critical points
discussed in the
selected review articles
(Highlights and
strengths)
Review coverage relevant to antibiotic removals during pharmaceutical wastewater treatment system
Target pollutants General wastewater
composition
Membrane-based treatment process Advanced oxidation processes (AOPs) Catalytic
membrane
reactor
Separate
membrane process
Membrane-
incorporated
bioreactor
Photo/Fenton
oxidation
process
Electrochemical
oxidation
Ozonation Photocatalysis
process
- Reviewed the optimal
conditions and
removal efciency of
different
technologies
- Discussed about
perspectives and
challenges during
pharmaceutical
wastewater
treatment
[27] - Overview focus on
the photocatalytic
membrane (PM)-
based treatment of
water and waster-
containing pharma-
ceutical and personal
care products
(PPCPs)
contaminants
- Discussed about the
fabrication of PM and
key parameters for
enhanced removal of
PPCPs from aquatic
system
- Discussed
perspectives and
challenges during
PPCP removal
- General
pharmaceutical
wastewater
- Not covered - Briey discussed
about
microltration
(MF), UF,
nanoltration
(NF), and
reverse osmosis
(RO) membrane
- Not covered - Not covered - Not covered - Not covered - Discussed
various
photocatalyst
applications for
PPCP
degradation
- Not covered
[31] - Discussed the
occurrence of
pharmaceutical
residues in water
bodies
- Emphasized the
application of nano-
enabled photo-
catalyst for the
degradation of
pollutants
- Discussed scale-up at
industrial level, eco-
nomic feasibility
studies, and life cycle
assessment for nano-
photocatalysts appli-
cation in wastewater
treatment
- Discussed the
sources of the
pollutants in
pharmaceutical
wastewater
- Discussed the
types and
concentrations of
pollutants in
wastewater
- Not covered - Not covered - Briey
discussed in
the
introduction
and general
methods of
treatment
- Briey discussed in
the introduction and
general methods of
treatment
- Briey
discussed in
the
introduction
and general
methods of
treatment
- Discussed in
detail about the
fabrication,
operating
parameters, and
degradation
mechanism
- Not covered
(continued on next page)
R. Kumar et al.

Journal of Water Process Engineering 58 (2024) 104838
5
Table 1 (continued )
References Critical points
discussed in the
selected review articles
(Highlights and
strengths)
Review coverage relevant to antibiotic removals during pharmaceutical wastewater treatment system
Target pollutants General wastewater
composition
Membrane-based treatment process Advanced oxidation processes (AOPs) Catalytic
membrane
reactor
Separate
membrane process
Membrane-
incorporated
bioreactor
Photo/Fenton
oxidation
process
Electrochemical
oxidation
Ozonation Photocatalysis
process
[32] - Discussed the
limitations of
biological and
physical methods
during the treatment
of pharmaceutical
wastewater
- Discussed various
AOP methods
(electrochemical and
photocatalytic
methods)
- Evaluated UV/
chlorine-based AOPs
as best methods for
pharmaceutically
active compounds
(PhACs), i.e., carba-
mazepine (CBZ)
- Discussed the
degradation
process of CBZ as
target PhACs
- Not covered - Not covered - Discussed in
brief during
the
biological
method of
PhAC
treatment
- Discussed
briey the
chemical and
catalytic
degradation
of PhACs
- Discussed in detail
the application of
various materials
during the
electrochemical
oxidation of PhACs
- Discussed
briey the
chemical and
catalytic
degradation
of PhACs
- Discussed in
detail about the
application of
various materials
during
photocatalysis of
PhACs
- Not covered
[33] - Focused on organic
contaminants
treatment in
pharmaceutical
wastewater using
biologicals and AOPs
- Discussed in detail
photocatalysts and
photo (electro)
catalysis processes
for pollutant
degradation
- Discussed in
detail about
various sources
of PhACs
- Not covered - Briey covered - Briey
covered
- Briey
discussed in
the
introduction
section
- Discussed in detail
about
electrocatalysts and
electrochemical
oxidation
- Not covered - Discussed in
detail about
various types of
photocatalysts
and degradation
mechanisms
- Not covered
[34] - Discussed toxicity,
occurrence,
constituents in
wastewater from
pharmaceutical
industries
- Focused on different
parameters of the
affection treatment
process during
conventional and
emerging
technologies
- Recommended
hybrid technologies
for effective
treatment of
pharmaceutical
wastewater
- Discussed the
sources,
constituents, and
presence of
PhACs (mean wt
%) in the
wastewater
- Presented
chemical
composition of
various
pharmaceutical
wastewater
- Discussed in
detail various
membrane
processes (MF,
UF, NF, and RO)
- Discussed in
detail as one
of the
emerging
treatment
technologies
- Discussed
mechanism
and removal
efciency
- Not covered - Briey
covered
- Discussed in
detail about
various types,
mechanism, and
removal
efciency
- Not covered
(continued on next page)
R. Kumar et al.