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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Aquatic Contamination Authoritative resource presenting techniques and technologies to sustainably neutralize environmental contamination in aquatic plants, microorganisms, and more Two thirds of the Earth is covered with aquatic habitats that play a key role in stabilizing the global environment and providing a wide variety of services to increasing human needs. Nevertheless, anthropogenic activities are rapidly destroying the quality of both fresh and marine waters globally, due to excessive use of chemicals, fertilizers and pollution from suburban and industrial areas eventually making their way into the aquatic world. Aquatic Contamination: Tolerance and Bioremediation presents the broader spectrum of biological applicability of microbes with better understanding of cellular mechanisms for remediation of aquatic contaminants. The book also focuses on practices involved in molecular and genetic approaches, necessary to achieve targets of bioremediation and phytoremediation to solve global water contamination problems. Such approaches pave the way for the utilization of biological assets to design new, efficient, and environmentally sound remediation strategies by inculcating genomic techniques at cellular and molecular levels with model assessment. Aquatic Contamination provides a comprehensive background for readers interested in all perspectives of the contamination of aquatic environs. It covers various research aspects which are being carried out globally to understand simulation models in the assessment of xenobiotics, role of genomics, transgenic plants, and microbial enzymes for degradation and removal of toxic substances in aquatic environs. Key features include: * Extensive coverage of interactions between plants, metals and microbes including the influence of biotic and abiotic factors * Comprehensive discussion of the details of molecular mechanisms from assimilation to detoxification levels * Exploration of the enzymatic approaches of potential plants acting as hyper-accumulators for contaminants in aquatic environs * Details of sustainable tools such as transgenic plants for the manipulation of important functional microbial genes to achieve higher certainty of bioremediation * Details of advances in tools and models like micro-arrays and simulation models for the complete assessment of xenobiotic compounds from cellular to degradation hierarchies Aquatic Contamination: Tolerance and Bioremediation will be substantially helpful to environmentalists, microbiologists, biotechnologists and scientists, providing essential information on various modern technologies for the remediation of contaminants in aquatic ecosystems.
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Table of Contents
Cover
Table of Contents
Title Page
Copyright Page
Dedication Page
About the Book
Key features
About the Editors
Preface
1 Emerging Techniques for Treatment of Wastewater
1.1 Introduction
1.2 Composition of Untreated Wastewater and Its Effect on Water Bodies
1.3 Strategies to Treat Wastewater
1.4 Tertiary Treatment
1.5 Natural Processes for Wastewater Management
1.6 Emerging or Advanced Techniques for the Treatment of Wastewater
1.7 Conclusion
References
2 Aquatic Ecosystems and Health Threats
2.1 Introduction
2.2 Threats to the Health of Aquatic Ecosystems
2.3 Data Analysis
2.4 Results from the Study
2.5 Conclusions
References
3 Endophytic Fungi and Bacteria
3.1 Introduction
3.2 Main Anthropogenic Sources Releasing HMs into the Environment
3.3 Phytoremediation of HMs
3.4 Advantages and Disadvantages
3.5 Factors that Increase HMs Phytoremediation
3.6 Phytoremediation Mechanisms
3.7 Microbiota in Plants Used in Phytoremediation
3.8 Bacteria that Enhance Phytoremediation
3.9 Conclusion
References
4 Mechanism of Heavy Metal‐Induced Stress and Tolerance
4.1 Introduction
4.2 Heavy Metal‐Induced Stress
4.3 Metal Tolerance Mechanisms
4.4 Root Exudates
4.5 Cellular Wall
4.6 Plasma Membrane
4.7 Vacuole
4.8 Xylem
4.9 Phloem
4.10 Sequestering of Metals in the Cytosol by Various Ligands
4.11 Considerations
4.12 Conclusion
References
5 Biotechnology for Sustainable Remediation of Contaminated Wastewater
5.1 Introduction
5.2 Organic Contaminants
5.3 Biotechnology in Environmental Engineering
5.4 Biological Treatment
5.5 Electrochemical Method
5.6 Heavy Metal Treatment
5.7 Conclusion
References
6 Novel Trends of Biotechnology in Wastewater Treatment
6.1 Introduction
6.2 The Nascent Organic Methods
6.3 Forthcoming Technologies/Incubating Ideas: Theory of Existential Growth
6.4 Conclusion: Progression of Trending Technologies in Water Science
Acknowledgments
References
7 Role of Free‐Floating Macrophytes in the Abatement of Disturbed Environments
7.1 Introduction
7.2 Nutrient Equilibrium
7.3 Importance of Free‐Floating Macrophytes in Ecosystem Structure and Function
7.4 How Toxins are Added to the Environment
7.5 Role of Aquatic Plants in Water Bodies
7.6 Phytoremediation
7.7 FFPs as Bioabsorbants
References
8 Enzymatic Approach for Phytoremediation
8.1 Introduction
8.2 Mechanism and Types of Phytoremediation
8.3 Conclusion
References
9 Phyto‐Metalloproteins and Restoration of Freshwater Ecosystems
9.1 Introduction
9.2 Phytoremediation
9.3 Role of Metalloproteins in Phytoremediation
9.4 Use of Phytometalloproteins for Remediation of Contamination and Restoration of Freshwater Ecosystems
9.5 Heavy Metal Uptake from Contaminated Water
9.6 Phytometalloproteins in Remediation of Contaminated Freshwater Ecosystems
9.7 Genetically Engineered or Modified Metalloproteins for Improved Remediation of Contaminated Water
9.8 Conclusion
References
10 Phytoremediation
10.1 Introduction
10.2 Need for Phytoremediation
10.3 Phytoremediation Approaches
10.4 Hyperaccumulation
10.5 Genetically Engineered Plants and Phytoremediation
10.6 Multiple Benefits of Phytoremediation from Ecological to Socioeconomic
10.7 Phytoremediation‐Theoretical Aspects
10.8 Phytomanagement: A New Paradigm
10.9 Future Prospects
10.10 Conclusions
References
11 Biotechnological Advancements in Phytoremediation
11.1 Introduction
11.2 Types of Phytoremediation
11.3 Types of Pollutants
11.4 Naturally Available Plant Species for Phytoremediation
11.5 Phytoremediation of Organic Pollutants
11.6 Advances in Biotechnological Approaches for Phytoremediation of Different Pollutants
11.7 Biotechnology Advances in the Phytoremediation of Inorganic Pollutants
11.8 Biotechnology Advances in the Phytoremediation of Organic Pollutants
11.9 Implications of Transgenic Plants for Phytoremediation against Herbicides
11.10 Nanomaterials‐Assisted Phytoremediation
11.11 Next‐Generation Sequencing and Omics Approach for Improving Phytoremediation
11.12 Gene Editing Tools and Phytoremediation
11.13 Conclusion
References
12 Phytoremediation of Pesticides and Heavy Metals in Contaminated Environs
12.1 Introduction
12.2 Mechanism of Phytoremediation by Heavy Metals
12.3 Factors which Affect Uptake Mechanisms
12.4 Strategies for Improved Efficiency of Phytoremediation
12.5 Metal Chelators Encoded by Overexpression Genes
12.6 Origins of Pesticide Entry into Water
12.7 Effects of Pesticides
12.8 Threats to Terrestrial Biodiversity
12.9 Impacts of Pesticides on Soil Ecosystem Services
References
13 Biotechnological Interventions for Removal of Heavy Metals and Metalloids from Water Resources
13.1 Introduction
13.2 Water Pollution
13.3 Heavy Metals and Metalloids
13.4 Effects of Heavy Metals and Metalloids on Water Pollution
13.5 Heavy Metal and Metalloids Removal
13.6 Bioremediation in Pollution Management
13.7 Biosensors
13.8 Biotechnological Methods Used in the Removal of HMMs
13.9 Conclusion
References
14 Microbial Biofilms – Pollutant Load Suppressor
14.1 Introduction
14.2 Characteristic Features of Biofilms that are Exploited for Bioremediation
14.3 Environmental Pollutants
14.4 Microbial Biofilms
14.5 Pesticide Degradation
14.6 Wastewater Treatment
14.7 Microbial Fuel Cells (MFCs)
14.8 Bioremediation of Organic Pollutants
14.9 Bioremediation of Heavy Metals
14.10 Toxicity of Heavy Metals
14.11 Conclusion
References
15 Recent Advances in the Biodegradation of Petroleum Hydrocarbons
15.1 Introduction: Aquatic Contamination Through Petroleum Hydrocarbons – Sources, Statistics, Impact, and Solution
15.2 Whole Genome Sequencing (WGS): History, Concepts, Methodology, Analyses, and Relevance to Biodegradation of Petroleum Hydrocarbons
15.3 Key Insights and Recent Advances from Studies on the WGS of Petroleum Hydrocarbon‐Degrading (Hydrocarbonoclastic) Bacteria in the Past Decade (2012–2021)
15.4 Future Research Directions in WGS Studies of Petroleum Hydrocarbon‐Degrading Bacteria
15.5 Conclusions
References
16 Green Synthesized Nanomaterials as Tools to Remediate Aquatic Pollution
16.1 Introduction
16.2 Approaches of Nanoparticle Synthesis
16.3 Routes of Metal Nanoparticle Synthesis
16.4 Applications of Green Nanomaterials in the Remediation of Aquatic Pollution
16.5 Conclusion
References
17 Nanotechnology‐Based Applications
17.1 Introduction
17.2 Nanotechnology: A Reliable Tool
17.3 Main Nanotechnological Processes for Water Purification and Wastewater Treatment
17.4 Polymer‐Based Nanoabsorbents
17.5 Membrane‐Based Technology
17.6 Nanomaterials for Microbial Control and Disinfection
17.7 Photocatalytic‐Based Technology
17.8 Conclusions and Future Outlook
Acknowledgments
References
18 Reliability on Nanoscience
18.1 Introduction
18.2 Wastewater's Pollution
18.3 Nanotechnology and Nanomaterials
18.4 Nanoscience and Wastewater Remediation
18.5 Conclusions
18.6 Future Perspectives
References
19 Transgenic Plant Technology and its Role in Bioremediation
19.1 Introduction
19.2 Transgenic Plant Technology
19.3 Transgenic Plants in Bioremediation
19.4 Metal Accumulators
19.5 Need for Transgenic Plants
19.6 Phytoremediation Via Chelation
19.7 Phytovolatilization
19.8 Chemical Modification
19.9 Risk Assessment
19.10 Future Perspectives
References
20 Comprehensive Note on Various Wastewater Treatment Strategies
20.1 Introduction
20.2 Treatment Strategies
20.3 Methods of Wastewater Treatments
20.4 Electrochemical Methods of Wastewater Treatment
20.5 Biological Treatment
20.6 Strategies for Biological Treatment
References
21 Case Studies of Aquatic Contamination and Bioremediation
21.1 Introduction
21.2 Water Contamination
21.3 Noxious and Hazardous Combinations in Diesel‐Tarnished Water
21.4 Halophilic Tiny Creatures Expected to Work as Bioremediation Trained Professionals
21.5 Parts Drew in with Diesel Bioremediation by Organisms
21.6 Conclusion
References
Glossary
Index
End User License Agreement
List of Tables
Chapter 2
Table 2.1 Nickel concentrations in plant parts (mg/kg), sediments (mg/kg), ...
Chapter 3
Table 3.1 Average natural contents in selected rocks with HMs (values in mg...
Table 3.2 Plant species used for phytoremediation.
Table 3.3 Advantages and disadvantages of phytoremediation (Diarra et al. 2...
Table 3.4 Effects of endophytic and mycorrhizal fungi on HMs phytoremediati...
Chapter 4
Table 4.1 Plant species and main organs involved in metal uptake.
Chapter 5
Table 5.1 Various processes used for the treatment of wastewater.
Table 5.2 Combined technology.
Table 5.3 Techniques used for the treatment of pharmaceutical industrial wa...
Chapter 6
Table 6.1 List of enzymes and their role in wastewater treatment.
Table 6.2 Oligonucleotide probes used to detect chemolithoautotrophic proka...
Chapter 7
Table 7.1 Free‐floating macrophytes for accumulating various heavy metals....
Chapter 9
Table 9.1 Efficient HM‐hyperaccumulators for phytometalloproteins‐mediated ...
Chapter 10
Table 10.1 Strategies of phytoremediation with description, benefits, and w...
Table 10.2 List of metal and metalloid hyperaccumulators.
Table 10.3 Plants used in the process of sustainable phytoremediation/phyto...
Chapter 11
Table 11.1 List of hyperaccumulator phytoremediators used against various i...
Table 11.2 List of the transgenic plants transformed using PCs, MTs, and GS...
Table 11.3 List of the transgenic plants engineered against heavy metals, x...
Chapter 12
Table 12.1 Plants with phytoremediation potential and their role in elimina...
Table 12.2 Types of pesticides.
Chapter 13
Table 13.1 Ecological status of some heavy metals and metalloids.
Chapter 15
Table 15.1 Petroleum hydrocarbons degraded or potentially degradable by HDB...
Table 15.2 Summary of highlights from WGS and biodegradation potential of p...
Table 15.3 Putative gene clusters/operons involved in the biodegradation of...
Table 15.4 Summary of the genes involved in biodegradation of selected hydr...
Table 15.5 Results of comparative genomics analysis of bacteria belonging t...
Chapter 16
Table 16.1 Biosynthesis of metal nanoparticles.
Table 16.2 Application of green synthesized nanoparticles in wastewater tre...
Chapter 18
Table 18.1 Some examples of nanomaterials that can be used to remediate aqu...
List of Illustrations
Chapter 1
Figure 1.1 Scheme for handling wastewater.
Figure 1.2 Simplified diagram of the primary treatment.
Figure 1.3 Simplified illustration of the secondary treatment.
Figure 1.4 An activated device of sludge.
Figure 1.5 Main parts of a trickling filter.
Figure 1.6 Diagram of an RBC reactor.
Figure 1.7 Oxidation ditch.
Figure 1.8 Constructed wetland (subsurface flow system).
Figure 1.9 Constructed wetland (free water surface system).
Figure 1.10 Microbial fuel cell technology benefits.
Chapter 2
Figure 2.1 Location map showing the sample collection localities from the re...
Figure 2.2 The photographic views of the studied localities. (a) locality 4;...
Figure 2.3
Nuphar lutea
(right) and
Nymphaea alba
(left).
Figure 2.4 General views of the seasonally investigated localities in the Gö...
Figure 2.5 Samples collected from the localities. (a) recording location par...
Figure 2.6 Sample preparations for analysis. (a) grinding of oven‐dried plan...
Figure 2.7 Anthropogenic factors causing pollution in the Gölbaşı Lake. (a–d...
Chapter 3
Figure 3.1 Main anthropogenic sources of heavy metal release into the enviro...
Figure 3.2 Overview of mechanisms of HMs' uptake.
Figure 3.3 Speciation diagram of Cu(ll)/OH/CO
3
.
Figure 3.4 Positive effects of endophytic and mycorrhizal fungi on plant dev...
Figure 3.5 Mechanisms of action of rhizosphere microorganisms in the remedia...
Chapter 4
Figure 4.1 ROS generation and stress tolerance mechanisms induced by heavy m...
Figure 4.2 Involvement of root exudates in metal tolerance.
Figure 4.3 Primary wall components involved in metal tolerance. (a) Cellulos...
Figure 4.4 Secondary wall components involved in metal tolerance.
Figure 4.5 Plasma membrane metal transport mechanisms.
Figure 4.6 Mechanisms of metal transport to the vacuole.
Figure 4.7 Mechanism of metal transport in the xylem and phloem.
Figure 4.8 Synthesis and composition of Glutathione.
Figure 4.9 Phytochelatin synthesis.
Figure 4.10 Structure of metallothioneins.
Figure 4.11 Main organic acids involved in metal chelation.
Chapter 5
Figure 5.1 The mechanism of removal of wastes from contaminated water.
Figure 5.2 The process of activated sludge for the treatment of wastewater....
Figure 5.3 Membrane bioreactor for the treatment of wastewater.
Figure 5.4 The mechanism of removal of phosphorus from the wastewater.
Chapter 6
Figure 6.1 Contribution of biosensors in wastewater treatment.
Chapter 8
Figure 8.1 Mechanisms of phytoremediation with microbial assistance.
Figure 8.2 Categorization of oxidoreductase.
Chapter 10
Figure 10.1 Factors influencing phytoremediation.
Figure 10.2 Flow chart showing the basic process of metal hyperaccumulation ...
Chapter 11
Figure 11.1 Various mechanisms involved in phytoremediation.
Figure 11.2 Representative diagram showing different types of pollutants and...
Figure 11.3 Outline for the use of the multiomics approach for a better phyt...
Chapter 12
Figure 12.1 Mechanism of phytoremediation.
Chapter 13
Figure 13.1 Heavy metal sources causing environmental pollution.
Figure 13.2 Various mechanisms used in phytoremediation.
Figure 13.3 Some types of biosensors.
Chapter 15
Figure 15.1 Key milestones in research on the WGS of hydrocarbonoclastic bac...
Figure 15.2 Stages in a typical WGS pipeline.
Figure 15.3 Sunburst chart showing the diversity of environments from where ...
Figure 15.4 A typical workflow for analyses of WGSs.
Figure 15.5 Translated amino acid sequences from the partial 16S rRNA gene s...
Figure 15.6 Principal substrates/classes of hydrocarbons degraded by HDB who...
Figure 15.7 Literature map of the pathways involved in the biodegradation of...
Figure 15.8 An integrated pathway for phenol metabolism in
Rhodococcus ruber
Figure 15.9 An example of a whole genome sequence map of the bacterium:
Rhod
...
Figure 15.10 Cell metabolism diagram of the first bacterium with potential H...
Figure 15.11 Cell metabolism diagram for
Alcanivorax borkumensis
SK2. Cell s...
Figure 15.12 Distribution of genes responsible for xenobiotics degradation f...
Figure 15.13 Relative distribution of genes responsible for xenobiotics degr...
Chapter 16
Figure 16.1 Two approaches for synthesizing nanoparticles (a) Top‐down appro...
Figure 16.2 Application of green synthesized nanoparticles (NPs) in wastewat...
Chapter 17
Figure 17.1 A drawing depicting the disadvantages of some of the conventiona...
Figure 17.2 A generalized schematic representation of nanotechnology and its...
Chapter 18
Figure 18.1 Mechanisms of treating wastewater to promote remediation using n...
Guide
Cover Page
Title Page
Copyright Page
Dedication Page
About the Book
About the Editors
Preface
Table of Contents
Begin Reading
Glossary
Index
WILEY END USER LICENSE AGREEMENT
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Aquatic Contamination
Tolerance and Bioremediation
Edited by
Rouf Ahmad BhatGowhar Hamid DarFernanda Maria Policarpo TonelliSaima Hamid
This edition first published 2024© 2024 John Wiley & Sons Ltd
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Library of Congress Cataloging‐in‐Publication Data applied for:
Names: Bhat, Rouf Ahmad, 1981– editor. | Dar, Gowhar Hamid, editor. | Tonelli, Fernanda Maria Policarpo, editor. | Hamid, Saima, editor.Title: Aquatic contamination : tolerance and bioremediation / edited by Rouf A. Bhat, Gowhar H. Dar, Fernanda M.P. Tonelli, Saima Hamid.Description: Hoboken, NJ : Wiley, 2024. | Includes index.Identifiers: LCCN 2023012172 (print) | LCCN 2023012173 (ebook) | ISBN 9781119989288 (hardback) | ISBN 9781119989295 (adobe pdf) | ISBN 9781119989301 (epub)Subjects: LCSH: Water–Pollution. | Bioremediation.Classification: LCC TD420 .A68 2024 (print) | LCC TD420 (ebook) | DDC 628.1/68–dc23/eng/20230330LC record available at https://lccn.loc.gov/2023012172LC ebook record available at https://lccn.loc.gov/2023012173
Cover Design: WileyCover Image: Courtesy of Rouf Bhat
This book is dedicated to the mothers of all the editors of this book.
About the Book
More than two‐thirds of earth is covered with aquatic habitats that play a key role in stabilizing the global environment and providing a wide variety of services to increase human needs. Nevertheless, anthropogenic activities are rapidly destroying the quality of both fresh and marine waters globally due to excessive use of chemicals and fertilizers, and pollution from suburban and industrial areas eventually makes their way into the aquatic world.
To preserve the integrity of aquatic environs is the greatest challenge in current era because more than 80% of urban wastewater, millions of tons of heavy metals, toxic chemicals, sludge, fertilizers, and other waste are being directly discharged into inland waters. There are huge issues involved with technological facilitation and need large investment funds.
This book presents the broader spectrum of biological applicability with better understanding of cellular mechanisms for remediation of aquatic contaminants. Besides, it focuses on practices involved in molecular and genetic approach, necessary to achieve target of bioremediation and phytoremediation to solve the global water contamination problems. Such approaches pave the way for the utilization of biological assets to design new, efficient, and environmentally sound remediation strategies by inculcating genomic techniques at cellular and molecular levels with model assessment.
The content of the book provides a comprehensive background for those who are interested to look upon all perspectives of contamination of aquatic environ. It covers various research aspects that are being carried globally to understand the simulation models in assessment of xenobiotic, role of genomics, transgenic plants, and microbial enzymes for degradation and removal of toxic substances in aquatic environs. In general, it will be very much helpful to the environmentalists, microbiologists, biotechnologists, and scientists and enlighten them on various modern technologies for remediation of contaminants in aquatic ecosystems.
Key features
The book covers every interaction between plant, metal, and microbes including influence of biotic and abiotic factors.
It discusses comprehensive details of molecular mechanism from assimilation to detoxification levels.
It includes the enzymatic approaches of potential plants that act as hyperaccumulators for contaminants in aquatic environs.
It contains sustainable tools such as transgenic plants to manipulate important functional microbial genes to achieve higher certainty of bioremediation.
It provides advancement tools and models such as microarrays and simulation models for the complete assessment of xenobiotic compounds from cellular to degradation hierarchies.
About the Editors
Dr. Rouf Ahmad Bhat (PhD) has pursued his doctorate at Sher‐e‐Kashmir University of Agricultural Sciences and Technology Kashmir (Division of Environmental Sciences) and presently is working in the Department of School Education, Government of Jammu and Kashmir. Dr. Bhat has been teaching graduate and postgraduate students of environmental sciences for the past 3 years. He is author of more than 55 research articles (h‐index 25; i‐index 35; total citation 2000) and 40 book chapters and has published more than 32 books with international publishers (Springer, Elsevier, CRC Press Taylor and Francis, Apple Academic Press, John Wiley, and IGI Global). He has specialization in limnology, toxicology, phytochemistry, and phytoremediation. Dr. Bhat has presented and participated in numerous state, national, and international conferences, seminars, workshops, and symposium. Besides, he has worked as an associate environmental expert in World Bank‐funded Flood Recovery Project and also the environmental support staff in the Asian Development Bank (ADB)‐funded development projects. He has received many awards, appreciations, and recognition for his services to the science of water testing, air, and noise analysis. He has served as an editorial board member and a reviewer of reputed international journals. Dr. Bhat is still writing and experimenting with diverse capacities of plants for use in aquatic pollution remediation.
Dr. Gowhar Hamid Dar (PhD) is currently working as an assistant professor in environmental science, Sri Pratap College, Cluster University Srinagar, Department of Higher Education (J&K). He has a PhD in environmental science with specialization in environmental microbiology (fish microbiology, fish pathology, industrial microbiology, taxonomy, and limnology). He has been teaching postgraduate and graduate students for the past many years at Postgraduate Department of Environmental Science, Sri Pratap College, Cluster University Srinagar. He has more than 70 research articles (h‐index 15; i‐index 20; total citation >700) in international and national journals of repute and more than 20 books with international publishers (Springer, Elsevier, CRC Press Taylor and Francis, Apple Academic Press, John Wiley, and IGI Global) to his credit. Moreover, he is supervising a number of students for the completion of degrees (PhD/Masters). He has been working on the isolation, identification, and characterization of microbes for a decade to understand their utility for humans. His research is based to understand the pathogenic behavior of microbes and to particularly understand the impact of pollution on development of diseases in fish fauna for past several years. He has received many awards and appreciations for his services toward science and development. Besides, he also acts as a member of various research and academic committees. Further, Dr. Dar is principal investigator and coprincipal investigator for different R&D projects sanctioned by Government of India and Government of Jammu and Kashmir.
Dr. Fernanda Maria Policarpo Tonelli (PhD) is an Assistant Professor at Federal University of São João del Rei, Divinópolis, MG, Brazil, where she teaches graduate students. She specializes in biotechnology/molecular biology and has been studying nanomaterials’ green synthesis protocols and applications such as delivery and remediation, as same as allelopathic potential of secondary metabolites from plants. The research projects resulted in 10 patent applications, 3 of them already analyzed and granted. She has published five books, authored 14 scientific articles and more than 30 book chapters with international publishers. She has presented and participated in many national and international conferences and has also had the opportunity to contribute to the organization of various scientific events. Dr. Tonelli has also dedicated herself to the promotion of science and technology through co‐funding a non‐governmental organization. Dr. Tonelli is active in scientific advocation groups for women. Her efforts as a researcher have been recognized with various awards, including For Women in Science Brazil (awarded by L‘Oréal Brasil, UNESCO in Brazil, and Brazilian Academy of Sciences) and Under 30 Brazil (Forbes) as well as various certificates of merit.
Dr. Saima Hamid holds doctorate as well as master's degree in environmental science from the University of Kashmir, India. She has qualified UGC‐NET exams multiple times and other state level exams. Her research area includes plant molecular biology, stress adaptations, bioactive compound isolation and characterization, climate change, and microbial biotechnology. She has published more than 30 research and review articles in highly reputed journals such as Elsevier, Frontier’s in Plant Sciences, Springer, MDPI, Wiley, and other peer reviewed journals. She is the cofounder of CERD Foundation and member of various international organizations that focus on plant adaptations and climate change. She is an international forum speaker from six years and columnist of various international magazines and local newsletters in different countries such as Island Chief of Maldives, Sri Lanka, Bangladesh, and many others.
Preface
Environmental pollution in the current scenario is a serious threat to all forms of living creatures. The water scarcity is a reality, although it covers the major part of Earth’s surface, helping to stabilize ecosystems. Industrialization does not consider sustainability principles and has established a concerning scenario worldwide. Anthropogenic activities have promoted contamination in aquatic ecosystems that leads to deterioration of freshwater qualities and hence makes it inadequate to be used by living beings. Inorganic, organic substances, and biological contamination released from different sources pose severe threat to quality aquatic ecosystems and make it unfit for dependent organisms.
The growing population, however, needs to receive clean water supply to live and maintain good health. So, it is necessary to develop efficient strategies to diminish and preferably stop pollution generated from domestic, industrial, and agricultural sources.
The book is dedicated to discussing the problems associated with contaminated aquatic environs and addressing strategies to preserve and restore the integrity of aquatic environs. Biological materials such as enzymes, microorganisms, and plants can be used in bioremediation protocols to offer low‐cost and eco‐friendly technologies to deal with contaminants of diverse chemical nature. The nanotechnology field can also offer materials that can be useful tools to promote polluted environments’ restoration. The aim of the book is to offer to undergraduate students and researchers a multidisciplinary and comprehensive approach to the theme, from a biotechnological point‐of‐view.
We are extremely grateful to all the authors who have contributed chapters in this project and to the project handling team of John Wiley & Sons, Inc., for their generous cooperation and for publishing this book.
Rouf Ahmad BhatGowhar Hamid DarFernanda Maria Policarpo TonelliSaima Hamid
1Emerging Techniques for Treatment of Wastewater
Naseema A. Wani1, Nazir A. Malik2, Younas R. Tantary3, Ishrat Jan4, Tawseef Ahmad5, and Mohammad S. Wani6
1 Department of Botany, Punjabi University, Patiala, Punjab, India
2 Department of Botany, Dolphin PG College of Science and Agriculture, Chandigarh, Punjab, India
3 Department of Botany, Government Degree College, Tangdhar, Jammu and Kashmir, India
4 Department of Zoology, University of Kashmir, Srinagar, Jammu and Kashmir, India
5 Department of Biotechnology, Punjabi University, Patiala, Punjab, India
6 Department of Agriculture, Government Mohindra College, Patiala, Punjab, India
1.1 Introduction
Water is exceptionally a prerequisite for sustaining earthly existence. While 70% of the earth is made up of water, it is surprisingly accessible to only less than 1%. The world population will increase by up to nine million by 2050 with the current population growth rate that may trigger serious freshwater shortages in the immediate future. It is predicted that access to clean water for human needs will be challenging around the globe by 2030, as natural freshwater resources may be under great strain (Wichelns et al. 2015). Regrettably, 97% of the world's surface water is saltwater; two‐thirds of the remaining 3% have frozen because 1% of the world's water source is not equally dispersed, and this scarcity is a major trouble in developing nations (Smith 2009). The most important prerequisite of each and every human being is the clean and potable water, but at the same time, usage of this is the utmost responsibility and concern of today's world. Some areas are supplied with water for this purpose despite constant rainfall. There is a shortage in this regard in some areas. In all regions across the globe, this creates a major obstacle in managing water distribution. Water is a predominant factor in the environment which influences human health and other living organisms. The physical and chemical facets of water quality have become a problem with the rise in population, as wastewater from various sources poses a serious threat. Globally, billions of people face the big issue of proper sanitation and clean water supply (WHO 2013). The rapid development of human society throughout the globe in the form of population growth, urbanization, and industrial development has led to an increase in the need for clean and safe drinking water on the one hand and the formation of wastewater on the other. In both the developed world and the developing world, human actions have contributed to water resource pollution by discharging harmful chemical substances from factories, industrial waste, agricultural land, etc., raising some additional load on accessible water supplies and generating large amounts of wastewater (Li et al. 2013). This wastewater approaching from various anthropogenic places is released in a very identical manner into distinct water bodies, which include streams, seas, oceans, and estuaries where it pollutes and significantly damages the aquatic vegetation and fauna. Over the years, various regulations, protocols, and procedures associated with the treatment and release of wastewater into water bodies have been developed and applied around the world and reused to address the continuing challenge of drinking water. But, alternatively, apart from all the rules and regulations, there is another sad truth that a substantial quantity of wastewater has been abandoned untreated or dealt with using strategies that are ineffective and discharged into the environment which subsequently ends in the degradation of the environment. These inadequate sanitation services result in many waterborne diseases (Bixio et al. 2006). According to the WHO, about 80% of the diseases in the developing world are water‐related, due to low water quality and lack of sanitation, and this is worse in rural areas (WHO 2013). Lack of sanitation contaminates watercourses around the world and is one of the most important sources of water contamination. Every year there are three million deaths from diarrheal diseases due to Escherichia coli, Salmonella and Cholera bacterial infections, as well as parasites and viruses. The number of children dying of diarrhea in the 1990s was much greater than the number of conflict‐ridden victims after World War II (Smith 2009). Furthermore, it is reported that approximately four million humans around the globe have little or no accessibility to safe and sanitized water sources and every year huge numbers of people die from waterborne diseases (Montgomery and Elimelech 2007; Malato et al. 2009).
In order to solve these issues, wastewater treatment is needed to reprocess wastewater in a useful way from distinctive sources. Wastewater treatment approaches that are currently in use have been validated to be effective in the past, but there is a desperate need to reconsider and develop current policies and procedures and create new wastewater management systems if you want to lessen the environmental risk. Another prime advantage of wastewater treatment is that it can be utilized for consuming purposes that will significantly reduce the burden on natural freshwater supplies from increasing water requirements. The World Health Organization reported that 1.1 billion people did not have access to safe drinking water in 2015. So, purifying wastewater and keeping it safe to drink can help reduce the need for drinking water.
1.2 Composition of Untreated Wastewater and Its Effect on Water Bodies
Defining wastewater really is difficult. Water consideration in its natural state, i.e. water from streams, lakes, and rivers, contains a wide range of minerals, nutrients, and suspended and dispersed substances. The water that is employed for one reason may not be suitable for another. Therefore, to explain the purity of water, there is a list of criteria set by various countries for different water groups. In order to make sure of the availability of clean water, changes are made regularly on the basis of the databases accessible across the planet from certain water and health regulatory authorities. Any degradation in water quality due to the involvement of human activities is water pollution. Anthropogenic and ecological waste both together contribute with regard to the switch in the natural constitution of water. Wastes discharged into water bodies of one country do not remain restricted to specific limits, and this leads to an increase in conflict between bordering nations. Therefore, it is an international concern and that is why it needs global support. Every segment of society has been experiencing an increasing need for sustainable use of resources. Wastewater is any water that has been influenced by human consumption. Wastewater is used water from any mechanical, residential, or arming exercises, stormwater, surface overflow, or any sewer inflow or sewer penetration (Almuktar et al. 2018). Because of the water global scarcity issues, the situation is fundamental to consider nonconventional sources of water for satisfying the increase in the need for freshwater. Wastewater is considered an acceptable solution suitable for addressing the scarcity of water resources caused by multiple factors such as population progression (Bichai et al. 2012; Almuktar and Scholz 2016). However, the unbelievable diversity in wastewater sources intrusive of organic and inorganic elements generates the recycling of that water condition to ordered checking to evaluate incoming hazards affecting the overall environment (FAO 2003). Only 20% of the total wastewater produced is treated before it is delivered into the environment (UNESCO 2012). Satisfactory recycling of wastewater is important to look after the health of the community, the environment, and water resources.
Wastewater normally originates from various anthropogenic places that lead to various forms of contaminants and pollutants present in it counting organic, inorganic, and biological origin (Das et al. 2014). Inorganic contaminants and heavy metal pollutants, viz. copper, cadmium, nickel, and zinc, other chemical toxins and pollutants, such as colorants, detergents, hydrocarbons, and biodegradable substances, are contained in drinking water. Also contained in wastewater are biological pollutants, such as bacteria, microorganisms (pathogenic and nonpathogenic), fungi, and viruses (UN Water 2015). All of the three wide variety of contaminants and pollutants discussed if left untreated or not properly handled affects and impacts the environment in a dangerous way that leads to the degradation of the environment and its related problems. The level of impact depends on the contaminant and pollutant type, form, and concentration.
As discussed earlier, wastewater is a complex mixture of many contaminants and pollutants discharged from domestic, industrial, and agricultural places and, when left untreated, these contaminants and pollutants will pollute the water bodies and produce a significant hazard to the water's natural environment.
Biological pollutants of wastewater by pathogenic or nonpathogenic sources from various sources directly or indirectly contaminate groundwater, which can contribute to infection outbreaks. Untreated wastewater from various places is of major concern due to the long‐term effect of water resources on the aquatic environment.
1.2.1 Effect on River Water
Globally, river water is the main source of freshwater for humans, and any pollution of any sort would directly impact the human population. Since river water is an important source of freshwater, it also acts as an important waste disposal center to prevent the treatment of wastewater generated from various sources. These all have a direct effect on river ecology, affecting environmental cycles (Sharma et al. 2019). Wastewater changes the natural environment of rivers. An excessive quantity of toxins and pollutants leads to nutrient accumulation in the rivers resulting in eutrophication (Kanu and Achi 2011). A large amount of growth in river water results in the reduction of oxygen which interferes with the growth of natural aquatic organisms and can lead to the destruction of aquatic life. Industrial and mining effluents containing heavy metals such as arsenic, cadmium, and lead in rivers may result in the addition of these metals that can further lead to biomagnifications of these organic compounds in organisms. Industrial wastewater also produces acid waste resulting in the acidification of the river water by increasing its pH and temperature and thereby destroying the aquatic environment (Akpor and Muchie 2011; UN Water 2015). The presence of hazardous substances will adverse the aquatic health. This is further worsened by the excessive population of waterborne pathogens. Using microbiologically polluted water for household and other uses is harmful to human health and the entire environment. The prolonged exposure of rivers to untreated wastewater can forever alter their composition and properties, which influence normal aquatic life growth and survival. Suspended solids in rivers reduce sunlight penetration and consequently decrease photosynthesis, preventing the growth of aquatic plants and bacteria that sustain and stabilize rivers (Akpor and Muchie 2011).
1.2.2 Effect on Marine Environment
Discharge of untreated wastewater into marine ecosystems, for instance, oceans and seas, has a negative impact on the survival and growth rate of the sea species. The degree of the decline is predicated on the solubility, concentration, and retention of heavy metals, pesticides, insecticides, pharmaceuticals, microorganisms, fossil fuels, hazardous chemicals, and their residues in the contaminants and pollutants found in wastewater. They all may have a worrying effect on the life of the sea. This may build up or bioconcentrate in the species. Wastewater being inaugurated into seawater is detrimental to aquatic life because of increased toxicity. This enhanced toxicity may cause acute and lasting destruction to marine life and will eventually lead to the disruption of the biological cycle (Ren et al. 2017). To investigate the major effect of these toxins and pollutants on aquatic life, much research has been done on one of the diverse, in addition to the most delicate, fragments of marine ecosystems, the coral reefs. The consequences of numerous researches have revealed that the association between wastewater and marine environment destruction is quite consequential and is creating a serious threat to marine life. Industrial wastewater, sewage wastewater, and fertilizer waste are damaging the coastal regions and coral reefs to a greater degree and are also changing the entire water quality of oceans and seas and this in turn is hampering the survival and growth rates of marine life. Another primary point noted was that the polluted sites spread their contamination to unpolluted areas through water currents in oceans and seas, therefore troubling remote areas. Another issue that has a huge impact is the decalcification of calcium carbonate structures contained in the aquatic system. Biogenic calcification is an important process in the marine ecosystem process in which various calcium carbonate structures are being produced that enable several marine organisms to evolve. Calcium carbonate structures in marine organisms has many advantages such as predator defense and mechanical support (Andersson and Gledhill 2013). With the aid of calcium carbonate structures surrounding them, these coral reefs can develop in shallow ocean waters, thereby aiding in providing habitat to other organisms. Acidification of oceans causes erosion and decalcification of these structures leading to the degradation of coral structures. There is a correlation between the calcification and decalcification process that conserves the coral reef biodiversity. Ocean acidification indicates the pH of marine water is transferring toward a low alkaline state which is creating significant damage to the aquatic life (Abbasi and Abbasi 2011). One probable reason for acidification may be the disposal of commercial wastewater comprising toxic metals and others chemicals. These acids can pollute the water and stay there for a significant period of time, changing the average pH of the oceanic waters. The coastal waters encountering contaminated wastewater have elevated levels of nutrient content that leads to algal bloom and decreases the oxygen content in water leading to an unbalanced growth of aquatic organisms and also changing the ratio of coral reef communities. The ratio of coral cover and fish population diminishes with the increasing pollution. It was also observed that due to the low quality and high nutrient content in coastal waters, the amount of dead coral is higher and, at the same time, the proportion of algae increases.
Another dominant aspect which is being taken into account for deteriorating aquatic life is the nutrient enrichment of marine water. Untreated sewage and fertilizer waste are contributing to the nutrient enhancement of marine water in a massive way and damaging aquatic life. Nutritional enhancement results in a strong increase in the concentration of inorganic compounds such as phosphate, nitrate, and ammonium. Prolonged persistence causes chemical imbalances in marine waters and increases algal growth, decreasing photosynthetic activity and oxygen levels of aquatic plants, thus consequently influencing their growth. The nutritional enhancement also results in coral reef bleaching, which leads to the loss of coral cover around the globe (Wiedenmann et al. 2013).
1.3 Strategies to Treat Wastewater
With the fast growth in human population and industrialization, the challenges of acquiring water resources and disposing of wastewater will become increasingly more and more difficult. People around the globe express trouble in this sector and assembled various meetings and plans for environmental protection. Various intellectuals expressed profound concern over the continued deterioration of natural resources and proposed remedies by introducing different goals.
Most importantly, one such idea is ecological understanding that directs to exploring the accessible environmental information and implementing those concepts for designing new projects to accomplish the target of sustainable growth without harming the environment and balance the needs of future generations. The essence of ecological understanding can also be implemented in plotting wastewater treatment methods by making use of soil, plants, and microorganisms. Many such strategies are presently being used like aquatic ponds, wetlands, trickling filters, activated sludge method, and rotating biological contactor (RBC) techniques. Treatment refers to the reduction of value contaminants or pollutants in wastewater until they are released into the atmosphere with low negative impacts. The method of treatment differs considerably and depends on factors such as technology complexity, affordability, cost, efficiency, and the type of wastewater involved such as industrial, agricultural, or urban. There are several standards and rules developed by specific countries in order to preserve the quality of water and industries related to acceptable amounts of toxic components in their waste.
The drinking water standards are divided into two categories: primary and secondary. The primary requirements are legal and designed to govern potentially dangerous substances such as organic and inorganic chemicals and microbes in order to guarantee a safe public water supply. On the other hand, the secondary requirements, which are not enforced by law, mainly involve color and odor. So it is not a matter of great concern.
Technology is rapidly evolving and is indirectly disrupting natural wealth, especially water. The byproducts and waste produced by these activities add xenobiotic components that are challenging to deteriorate by natural processes. Therefore, there is a need for improved treatment strategies to deal with this ever‐changing waste matter (Sharma et al. 2019). The type of wastewater treatment techniques relays on the kind of environment where the wastewater will later be released and what kind of effect it would have on that specific environment (Laugesen et al. 2010). The wastewater treatments are classified into different stages depending on the procedure involved and the methodology used to meet the required standards. The easiest kind of categorization is mainly based on natural and advanced methods. But globally the most acceptable and widely studied methods of treatment schemes were divided into three main classes: primary, secondary, and tertiary schemes (Figure 1.1). These strategies often comprise various forms of physical, chemical, and biological treatment methods.
The treatment of wastewater is done to make it acceptable for release or reuse into the system again. The types and degrees of the treatment process used depend on the efficiency of the wastewater disposal and the intended use of treated water. For example, the water for the use of domestic consumption should not contain any type of microbial contamination such as pathogens but may contain tracer amounts of calcium and magnesium salts. However, boiler water may contain microorganisms and even pathogen‐causing diseases but calcium and potassium salts (hardness) are not allowed as they can cause the scaling of the reactor and prevent heat transfer. Wastewater released into the water bodies requires less intense treatment as compared to the water which has to be reused. The purpose of a modern wastewater treatment system is to generate clear, free‐from‐suspended solids, safe water that should be free from disease‐causing microorganisms.
1.3.1 Primary Treatment
The primary treatment highlights physicochemical and mechanical approaches which do not have a significant impact on the chemical oxygen demand (COD) and the biological oxygen demand (BOD) of the effluent. It is highly intended to reduce the bulkiness of the effluent with the aid of removing pollutants which could interfere with the further operating facility of the sewage treatment plant. The purpose of primary treatment in particular is the removal of organic and inorganic solvents through sedimentation, as well as the removal of scum materials by skimming. During primary treatment about half of the biochemical oxygen demands, three‐fourths of the overall suspended solids, and the greater part of the oil and grease are separated. Several organic phosphorus, nitrogen, and heavy metals incorporated into solids are often separated throughout primary sedimentation. However, the colloidal and dissolved constituents are unaffected. Grit such as sand and heavy particles with high settling velocity are separated to avoid the rush of alternating wastewater treatment plants. Chemicals can be added to clarifiers to increase the rate of settling in order to increase the efficiency of the process. The primary treatment is meant for removing only those contaminants that have the tendency to float or be resolved under the influence of gravity. Therefore, there is a need to separate those contaminants which are in a suspended form and are mostly composed of oxygen‐demanding substances. Figure 1.2 shows the simplified diagram of the primary treatment.
Figure 1.1 Scheme for handling wastewater.
Figure 1.2 Simplified diagram of the primary treatment.
Figure 1.3 Simplified illustration of the secondary treatment.
1.3.2 Secondary Treatment
The primary treatment is accompanied by the secondary treatment, which is commonly known as biological treatment. Generally, secondary treatments include elimination of dissolved biodegradable and organic compounds that use biological treatments. The most popularly used biological treatment processes are tricky filters that are an unchangeable growth system and an activated sludge program that is a suspended growth system. Both systems are virtually used for the successful removal of total suspended solids (TSS) and dissolved BOD. A typical simplified plan of secondary treatment is revealed in Figure 1.3.
The biological treatment depends on the functioning of the microbial community. So, it is interesting the results can be obtained by providing the necessary growth conditions required for the existing community. Several parameters are considered to monitor the effect of processes such as residence time, hydraulic retention time, food‐to‐microbe ratio, rate of organic load, and rate of recycling. The most widely used activated sludge process is one of the oldest and main methods being used by the wastewater treatment industry.
1.3.3 Activated Sludge
Presently, the activated sludge system is probably the most successful and versatile method for the wastewater treatment process. Activated sludge designates scientific treatment methods that take advantage of an adjourned development of organisms to remove suspended solids and BOD. It relies on the rule that excess wastewater for air circulation to shape flocs of microorganisms decreases the organic matter and is separated by sedimentation (Narmadha and Kavitha 2012). The technique includes aeration and settles down the tanks and other accessories, reoccurrence and waste pumps, blowers and mixers for air circulation, and the device for flow measurement (Liu et al. 2011; Wu et al. 2012). Continuing the attention of active microorganisms in the reservoir, a portion of the activated sludge is reused (Xu et al. 2015). The activated sludge technique inhabits a small place as incorporated with a trickling filter and has better quality of waste. The only disadvantage is the significant amount of BOD in one end of the reservoir. However, on the other end, the microorganisms are more active physiologically until the mixer is entirely activated in the activated sludge system.
In the inactivated sludge method, various modifications have been made in order to get better results. By doing several modifications in the conventional type of facility like extended aeration, step aeration, mechanical aeration, and contact stabilization the efficiency of the activated sludge system can be increased. It is possible to modify the process by judiciously augmenting the sludge with acclimatized microbes and optimization of other parameters related to the process due to the development in technology. Apart from generating energy, these systems have the facilities to recover important resources from wastewater. A few years ago, research has been done in this area and therefore it is possible to retrieve many valuable products, such as fibers, cellulose biopolymers, and bioplastics (Guest et al. 2009; Lin et al. 2010; Ruiken et al. 2013). A general type of activated sludge system is shown in Figure 1.4 (Obuobie et al. 2006).
1.3.4 Trickling Filter
This is a developmental process wherein the microorganisms in charge of treatment are linked to a dormant pressing material. It is made of a circular reservoir with which it is a loaded product (volcanic, rock, or engineered material). Wastewater is pumped from above and seeps via filter media that allow organic material to be impregnated in wastewater by populated microorganisms such as aerobic, anaerobic, algae, facultative bacteria, protozoa, fungi referred to the stream as a biological film, or slime layer (about the thickness from 0.1 to 0.2 mm). Trickling filters are effective in which waste eminence such as suspended solids and BOD elimination is significant. The method is less complicated compared to activated sludge method but requirements for repair and operation necessities are higher because of the energy consumption (Fahad et al. 2019). This process is definitely worth it compared with prosperous, densely populated areas which have good treatment of wastewater and better water system. And it is suitable for the treatment of gray water. Moreover, it requires more area contrasted with certain other technologies and has impending for filter flies and odor (Liu et al. 2011). The main components of a trickling filter are shown in Figure 1.5 (Xu et al. 2015).
Figure 1.4 An activated device of sludge.
Figure 1.5 Main parts of a trickling filter.
1.3.5 Rotating Biological Contactors
One of the natural methods for biological wastewater treatment is aerobic RBC. RBC is a different type of wastewater treatment method which associates benefits of fixed biological film, such as high concentration of biomass, short hydraulic retention time, fast operation, minimal energy cost, and insensitivity to hazardous material shock loads. Consequently, the aerobic RBC reactor is commonly used in the treatment of domestic and commercial wastewater (Amoatey and Bani 2011; Vianna et al. 2012). The RBC reactor schematic diagram is shown in Figure 1.6.
1.3.6 Oxidation Ditches
Oxidation Ditches (OD) are usually comprehensive mixing techniques however can be revised. Normal OD treatment methods constitute a single or multichannel arrangement inside a ring or oval. Initial treatment for instance grit elimination and bar screens usually leads to an oxidation ditch. Principal resolving proceeding to an oxidation ditch may also be used and tertiary filters might be needed following elucidation, reliant on the sewage necessities. Disinfection is necessary and reaeration could be required prior to final absolution. In the ditch oxygen transfer, circulation and aeration are provided by horizontally or vertically attached aerators (Zhang et al. 2014). The flow is aerated and blended with recovered sludge from a secondary clarifier in the oxidation ditch. In order to facilitate microbial growth, the mixing phase incorporates oxygen into the blended liquor and the drive velocity confirms microorganisms' contact with the powerful liquor (US‐EPA 2000). Figure 1.7 shows the diagram of oxidation ditch treatment (Amoatey and Bani 2011).
Figure 1.6 Diagram of an RBC reactor.
Figure 1.7 Oxidation ditch.
The secondary effluent consequently collected may be dealt with again by modern methods such as tertiary treatment followed by membrane filtration and disinfection to regain good‐quality potable water. Secondary treatments have been additionally divided into aerobic and anaerobic processes. The most extensively used aerobic processes have already been discussed earlier such as activated sludge, trickling filters, RBCs, and oxidation ditches. Among the anaerobic methods are anaerobic digestors, anaerobic filters, and upflow anaerobic sludge blanket reactor. Anaerobic methods are more beneficial than aerobic methods in terms of more energy production and biomass production in the form of methane gas possessing high calorific value (Metcalf and Eddy 2003).
1.4 Tertiary Treatment
Tertiary processing or advanced processing is used where it is required to remove particular components of wastewater that cannot be eliminated by secondary treatment. The tertiary treatment technique commonly known as effluent polishing is used to remove plant nutrients such as nitrogen and phosphorus which are responsible for the eutrophication of water bodies. This technique includes a diversity of processes performed on the effluent discharge from the secondary waste treatment process so that the water can be reused. It is employed when primary and secondary treatment cannot attain all that is needed. Suspended solids dissolved inorganic materials and organic compounds are eliminated by tertiary wastewater treatment. The tertiary treatment technique makes use of physicochemical and biological processes. Nitrogen removal can be done by the biological process which employs nitrification and denitrification with the application of additional aeration and nitrifying and denitrifying bacteria. Another method includes ammonia stripping where pH of water is first raised to alkaline range leading to the formation of ammonium ions followed by rapid flow of water at high speed through the long towers leading up to the removal of nitrogen in the form of ammonia gas. The removal of phosphorus is supported by chemical treatment facilitated by the addition of an alkaline chemical, alum, which results in precipitation (Nathanson 2000). The objective of the tertiary treatment is to eliminate nonbiodegradable toxic organic contaminants like polychlorinated biphenyls, chlorophenols, and other synthetic pollutants.
1.5 Natural Processes for Wastewater Management
Natural treatment strategies include the proper use of natural systems such as plants, soil, and microorganisms where pollutants and contaminants are eliminated without the help of any chemical. Natural treatment takes advantage of the following techniques to combat the wastewater epidemic.
1.5.1 Constructed Wetlands (CWs)
Wetlands constitute marshy areas which are composed of swampy forest areas and salt marshes and they can be artificial, natural, permanent, or temporary. The naturally existing wetlands are abundant in microflora and can be used for wastewater treatment. The constructed Wetlands (CWs) are near‐natural techniques and are fully engineered wetlands seen as the future of the wastewater treatment industry for which many newest investigations have been dynamically established in the past decades (Kayombo et al. 2000; Vymazal 2014). CWs are regions with a considerable depth possessing water in them and supporting the growth of different life forms including microorganisms as well as various plant forms such as reeds and sedges. CWs have been shown to make sure some benefits over conventional techniques. CWs are cost‐effective, east to operate and maintain, decrease the cost of the waste collection process, absorb low energy, promise appropriate reprocessing, can be worked on several levels, and increase visual importance to the atmosphere (Chen et al. 2008; Foladori et al. 2015
