Advancing wastewater treatment with Azolla filiculoides waste: a comprehensive review of adsorption applications

ABSTRACT

Rapid urbanisation and industrialisation have led to severe environmental pollution from the accumulation of wastewater and poorly treated or untreated industrial wastes. Traditional waste treatment methods are often expensive and ineffective in fully removing contaminants. As a result, there is a growing interest in exploring natural and cost-effective treatment systems. One such potential solution is the use of the aquatic fern, Azolla filiculoides Lam which has shown promise as a readily available, free-floating biomass that can effectively adsorb and remove metal ions and other pollutants from water. This review paper delves into the untapped potential of A. filiculoides bio-adsorbent, as a highly effective and eco-friendly solution for removing organic and inorganic pollutants from wastewater. The review also identified future research opportunities and recognised existing limitations in our understanding of A. filiculoides for wastewater treatment. Various aspects of its efficiency, including equilibrium isotherm, kinetics, thermodynamics, desorption, and adsorbent reclamation, have been studied. The research highlights A. filiculoides’s impressive maximum specific surface area of 484 m²/g, enabling it to adsorb a wide range of contaminants effectively. Among the studied adsorption models, Langmuir and pseudo-second-order models best described the adsorption phenomena on this bio-adsorbent. Thermodynamic evaluations further confirm that its waste can be utilised to construct feasible and spontaneous adsorption systems for efficient pollutant removal. It shows great promise as a bio-adsorbent to mitigate the adverse environmental impacts of wastewater pollution promoting sustainable water management practices. Further research and application of A. filiculoides in wastewater treatment could lead to substantial environmental benefits.

GRAPHICAL ABSTRACT

KEYWORDS:

• Azolla filiculoides
• waste conversion
• wastewater treatment
• adsorbent
• water pollution

Acknowledgements

We are thankful to Dr. Swagata Ghosh, Assistant Professor of English, Symbiosis Institute of Technology, Symbiosis International University, Pune, India for editing this manuscript. SG and SA conceptualised the idea. SG along with SA, AB, MM, BL, ZTAS, OJA, CO, AM, SZAN, HO, CB, CAI and AHB collected, analysed the data and drafted the manuscript. All the authors read, edited and approved the manuscript for publication.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Compliance with ethical standards

This article does not contain any studies involving human or animal subjects.

Ethics approval

This article does not contain studies involving human or animal subjects.

Data availability statement

The authors declare that the data used for this review were obtained from the literature.

Additional information

Notes on contributors

Soumya Ghosh

Dr. Soumya Ghosh is currently working as an Assistant Professor at the Natural and Medical Sciences Research Center, University of Nizwa, Oman since January 2024. Previously, he worked as a postdoctoral researcher at the University of the Free State, South Africa (2019–2024). Following his Ph.D. from Stellenbosch University, South Africa (2011–2015) he pursued his first postdoctoral studies at Thompson Rivers University, Canada (2016–2017). After returning from Canada, he joined as visiting faculty of Microbiology at Kuchaman College, Rajasthan, India. Prior to his PhD, Dr. Ghosh worked as a Research Fellow at the Biological Center, University of Gröningen, The Netherlands (2005). Thereafter, he worked as a Research Fellow at the Centre of Plant Molecular Biology, Tübingen University, Germany (2005–2008) where he secured his Biologie-Diplomarbeit (2005–2006) and consecutively at the Technical University Munich, Germany (2008 to 2010). Dr. Ghosh completed his Bachelor's degree in Microbiology from Garware College, Pune, India in 1999 and subsequently his Master's degree in Zoology at Pune University in 2001. Dr. Ghosh works in diverse fields ranging from plant biology to microbial diversity (bacteria and fungus). Recently, since 1st January 2024, Dr. Ghosh has been awarded the South African National Research Foundation (NRF)-C3 scientist rating.

Asmaa Benettayeb

Asmaa Benettayeb was born in Oran, Algeria in 1988 and received his formation and Ph.D. in Chemical Engineering from the University of Sciences and Technology of Oran Mohamed Boudiaf. His research focused on the development of new processes in relation to the field of environment and chemical engineering, especially in the field of water and wastewater treatment with extensive focus on adsorption and Chemical/physical modification of alginate, Chitosan, and other biosorbents for adsorption of heavy metals, Uranium, Rare earth elements, and water purification technology.

Maryam Meskini

Maryam Meskini is currently a Ph.D. student in Medical Bacteriology at the Pasteur Institute of Iran in Tehran. She holds a Master's degree in Medical Bacteriology from Baqiyatallah University of Medical Sciences, also in Tehran. Her research encompasses a diverse range of topics within medical bacteriology, with a particular focus on Mycobacterium tuberculosis, epigenetics, burn-related infections, and Pseudomonas aeruginosa. Maryam has an impressive publication record, with over 60 articles published in renowned scientific journals. Through her dedication and innovative research, Maryam aims to advance the field of medical bacteriology, contributing to better clinical outcomes and public health solutions.

Basant Lal

Dr. Basant Lal is working at the Department of Chemistry, GLA University, Mathura, India. He passed M.Sc. (1996) with first division from U.P. College Varanasi and obtained a Ph.D. degree from Banaras Hindu University. He has more than two decades of teaching and research experience and has taught UG and PG students. Presently, four Ph.D. students are working under his supervision. Dr. Lal is actively involved in research activities, has published more than 50 research papers in national and international reputed journals, and is also the author of two books.

Zainab T. Al-Sharify

Zainab T. Al-Sharify is an associate professor at the Environmental Engineering Department, University of Mustansiriyah. She is an honorary assistant professor at the Chemical Engineering Department, University of Birmingham, UK. She received her BSc and MSc from Al-Nahrian University, Iraq, and her PhD degree from the University of Birmingham, UK. Her research focuses on fluid flow, nanoparticles, computational fluid dynamics, and formulation technology. She has more than 140 published papers and 80 publications in Scopus-indexed journals. Her H-index is 27.

Oluwaseun Jacob Ajala

Oluwaseun Ajala is a highly accomplished individual who pursues excellence in the field of Chemistry. He is an esteemed academic staff member of Ladoke Akintola University of Technology Ogbomoso Nigeria. With over a decade of experience as a seasoned researcher, he has established himself as a leading authority in the field of chemistry. He has authored 27 international publications, and five book chapters, and has over 905 citations on Google Scholar, with an impressive 16 Hi index in Scopus. His research interests include the synthesis and characterization of nanomaterials, green chemistry, and environmental chemistry.

Christian Osagie

Christian Osagie currently works as a Reliability Engineer for Jones Lang LaSalle Incorporated (JLL) at their Nordestedt, Germany location. He does research in AOP process Nanotechnology, Water treatment, Stochastics, and their Applications, Chemical Process Safety and Reliability Engineering, Air Pollution and Adsorption Processes.

Alhadji Malloum

Dr. Alhadji Malloum is a PhD holder in Physical Chemistry and a leading researcher in Computational Physical Chemistry. Dr Alhadji Malloum is a Senior Lecturer at the University of Maroua (Cameroon) and a Postdoctoral Fellow at the University of the Free State (South Africa). His current research interests focus on computational methods for wastewater treatment, understanding the properties of liquids using molecular clusters, and investigating biological molecules. He also develops methodologies that apply machine learning to predict the adsorption capacity of materials characterized experimentally and advise on their efficiency against specific pollutants.

Shahad Z. Al-Najjar

Shahad Al-Najjar is a lecturer at the Chemical Engineering Department, al Nahrain University. She received her BSc and MSc from Al-Nahrian University, Iraq, and her PhD degree from the University of Birmingham, UK. Her research focuses on mass transfer and formulation technology. She has more than 20 published papers and 10 publications in Scopus-indexed journals. Her H-index is 9.

Helen Onyeaka

Dr. Helen Onyeaka is an Associate Professor in the School of Chemical Engineering at the University of Birmingham, UK, specializing in Sustainable Food Production, Food Waste Valorization, and Chemical Engineering. She teaches a range of microbiology courses and laboratory classes for both undergraduate and postgraduate students, focusing on Food Safety, Hygiene, and Management programs, including Masters/MSc/PG Diploma/PG Certificate, MSc Environmental Health, and MSc Public and Environmental Health.

Charné Bornman

Charné Bornman holds a degree in genetics and is currently leading research on building a fungal fuel cell at the University of the Free State, South Africa. She is proficient in Python and R and applies her expertise in machine learning and bioinformatics to explore novel applications in biotechnology and genetics. This work exemplifies her commitment to harnessing biological systems for sustainable energy and technological solutions.

Shabnam Ahmadi

Shabnam Ahmadi is currently a Ph.D. student at the Tarbiat Modares University, Iran. Previously she was a lecturer at the Department of Environmental Health Engineering at Zabol Medical University, Iran. Her research area focuses on the AOPS process, adsorption, and nanotechnology.

Chinenye Adaobi Igwegbe

Chinenye Adaobi Igwegbe (Ph.D. Chemical Engineering, COREN, PE) is a seasoned Lecturer and accomplished researcher in the Department of Chemical Engineering at Nnamdi Azikiwe University, Nigeria. With her expertise in wastewater treatment, biomass conversion/valorization, and process design/modeling and optimization, she has dedicated her career to advancing the field of Chemical Engineering. Currently, she is actively involved in the Poland Government Ulam National Agency for Academic Exchange (NAWA) for International Scientists 2022 research program at Wroclaw University of Environmental and Life Sciences in Poland, showcasing her commitment to global research collaboration. She has also published more than 150 journal articles, book chapters, and a book. Additionally, she has undertaken roles as both an editor and reviewer for various esteemed journals. Her research pursuits have yielded significant contributions to be ranked in the October 2023 Stanford University list of the top 2% of the world's scientists (in her fields of Chemical Engineering, Environmental Science, and Engineering). As a mentor and educator, she is deeply invested in cultivating the academic growth of aspiring engineers.

Ahmad Hosseini-Bandegharaei

Dr. Ahmad Hosseini-Bandegharaei received his bachelor‘s degree in Pure Chemistry in 2003 from Ferdowsi University and completed his postgraduate studies at Birjand and Semnan universities, under the supervision of Prof. M.S. Hosseini and Prof. M. Rajabi. His research interests are mainly focused on (i) the preparation of new adsorbents for both solid-phase extraction and determination of pollutants and their removal from waters and wastewaters and (ii) the development of new heterogeneous catalysts for mineralization of organic compounds, on which he works at Semnan University.