Skip to main content

Über dieses Buch

This book examines bioremediation technologies as a tool for environmental protection and management. It provides global perspectives on recent advances in the bioremediation of various environmental pollutants. Topics covered include comparative analysis of bio-gas electrification from anaerobic digesters, mathematical modeling in bioremediation, the evaluation of next-generation sequencing technologies for environmental monitoring in wastewater abatement; and the impact of diverse wastewater remediation techniques such as the use of nanofibers, microbes and genetically modified organisms; bioelectrochemical treatment; phytoremediation; and biosorption strategies. The book is targeted at scientists and researchers working in the field of bioremediation.



Chapter 1. Introduction to Environmental Protection and Management

Man’s environment consists of natural resources like air, land, water, plants, and animals. With the progress of industrialization and civilization, man has interacted with his surroundings and disturbed the nature. It leads to environmental pollution, which cannot be eradicated by nature’s self-acting process, i.e., various biogeochemical cycles. Environmental problems stem from two main categories of human activities: (a) resources utilization at unsustainable levels and contamination of the environment through pollution and (b) discharge of wastes at levels beyond the earth’s and environment’s capacity to absorb them or render them harmless which results in ecological damage and degradation of the environment. Environmental damage around includes pollution of water and air and consequent health problems, biodiversity loss, deterioration of buildings and monuments, soil fertility loss, desertification, ozone depletion, and many more. Environmental protection and management has become one of the foremost concerns of the world community. International concern for environmental protection and management has gained momentum with Stockholm Declaration in 1972. It is considered as Magna Carta of environmental protection and sustainable development. Then a series of global efforts have been undertaken internationally for protection of the environment. Hence, environmental protection has become not only local, regional, or national importance but also a global concern. Over the past several decades, growing public awareness regarding threats to the environment, informed by warnings from scientists, has led to demands that law protects the natural surroundings on which human well-being depends. Under growing pressure from national and international public opinion, governments began to demonstrate concern over the general state of the environment introduced legislation to combat pollution of inland waters, ocean, and air.
Sunita J. Varjani, Avinash Kumar Agarwal, Edgard Gnansounou, Baskar Gurunathan

Chapter 2. Mathematical Modeling in Bioremediation

Roughly 98% of the available freshwater is represented by the groundwater on the planet. Protecting and re-establishing groundwater quality is of great importance. A major threat to the resources of groundwater is soil and aquifer pollution by hazardous wastes. This pervasive issue represents an important practical and cost-effective challenge because underground environmental pollution is tough to locate and eliminate by conventional extraction and excavation methods. Thus, there is a necessity for a broader investigation of efficient, in situ remediation approaches that uses the benefit of natural phenomena, such as bioremediation and natural attenuation. This chapter gives a prologue to the essential hypothesis and utilization of contaminant transport demonstrating by numerical methods. In the wake of perusing this section, the reader ought to have the capacity to choose a proper numerical model for the circumstance under thought, run the code, and adjust it. The utilization of numerical methods to tackle groundwater contaminant transport issues has turned into a broadly utilized strategy in view of the intensive enthusiasm for groundwater quality and the quick improvement of processing innovation, which has made numerical simulations accessible to hydrogeologists and civil engineers. If suitably applied, numerical models can give answers to the following questions.
  • What is the relationship between solute concentration and location?
  • What will be the time taken to reach a target level of solution concentration due to remediation process?
  • Will a remedial measure reach a targeted concentration (reduced) in a certain time?
  • How might one recreate the historical data of contamination to discover the relationship between population, time of exposure, and concentration?
The chapter starts with fundamentals of groundwater flow. The concepts of groundwater such as hydraulic head, Darcy’s Law, hydraulic conductivity are discussed. Basics of transport processes, such as diffusion, advection that are involved in groundwater contamination, are also discussed. Later, theory of the model equations, assumptions considered, initial and boundary conditions are presented. In the latter sections, analytical and numerical models are discussed in detail with few recent advances in bioremediation modeling. The discussion presented here is considered to be basics yet should provide ample background for the reader concerned with the detailed workings of a numerical model.
Parthasarthy Vijay, Margavelu Gopinath

Chapter 3. Evaluation of Next-Generation Sequencing Technologies for Environmental Monitoring in Wastewater Abatement

The waste generation and disposal into natural water bodies become a serious topic to be concerned by researchers today. Consequently, there is a demand for new strategies and technologies to address wastewater treatment and subsequent recycle and reuse especially in arid/semiarid areas. The harmful microbial load in raw sewage, toxic chemicals, and nutrients may cause pollution and can render water utilities unfit for human consumption or recreational activities. Biological treatment process is advantageous and constitutes tools to biodegrade organic matter, transfer toxic compounds into harmless products, and remove nutrient in wastewater microbiology. Bio-monitoring employs sentinel or indicator species in water bodies to infer water quality, ecosystem health status, and to protect public health from waterborne risks. Next-Generation Sequencing is one of the most leveraging studies focus on the ecology of microbial-mediated processes that influence freshwater quality such as algal blooms, contaminant biodegradation, and pathogen dissemination. Sequencing methods targeting small subunit (SSU) rRNA hypervariable regions have allowed for identification of microbial species which serve as bioindicators for sewage contamination in raw, treated, semi-treated water utilities. In addition, hidden diversity of unknown or uncultured microorganisms reveals the genetic capabilities for biodegradation of toxins and other contaminants. This chapter aims to provide brief knowledge about the development of bioindicators for sewage pollution and microbial source tracking, characterizing the distribution of toxin and antibiotic resistance genes in water samples. The assessment of biological risk, suitability, and unfairness inherent in the application of Next-Generation Sequencing may be a prior concern.
P. Senthil Kumar, S. Suganya, Sunita J. Varjani

Chapter 4. Genetically Modified Organisms and Its Impact on the Enhancement of Bioremediation

Bioremediation is a process of degrading the environmental contaminants, that are introduced accidentally or purposely which cause hazardous effect on earth and harm the normal life process. The conversion of these contaminants into less toxic forms is the goal of bioremediation process that can be achieved by the use of microorganisms. The bioremediation approaches have more advantages when compared with the traditional methods, as it can be directly implemented at the targeted contaminant site. Even though some bacteria and fungus were employed to decompose the chemical compounds, but they have only limited ratio to metabolize the hydrocarbons on their own. The genetically modified organisms are applied nowadays in bioremediation process for effective removal of contaminants, where the indigenous microbes cannot degrade. Genetically modified microorganisms (GMOs) play an important role in remediating the industrial waste, reduce the toxicity of some hazardous compounds, and also help in removal of pollution by hydrocarbons and petrol discharges. A variety of molecular tools such as molecular cloning, horizontal transfer of DNA in bacteria, electroporation, protoplast transformation, biolistic transformation, conjugation and transformation of competent cells are available for the successful construction of GMOs. Transfer of gene into the bacteria makes it as a novel strain, for eliminating the hydrocarbon contaminants from the environment in minimal time. Similarly, removal of compounds such as xylene, toluene, octane, naphthalene and salicylate is coded on bacterial plasmids for successful degradation of the environment. This chapter represents the applications of genetically modified organisms in bioremediation processes, molecular tools used for construction of GMOs, pros and cons, ethical issues and laws governing the application of GMOs.
Narasimhan Manoj Kumar, Chandrasekaran Muthukumaran, Govindasamy Sharmila, Baskar Gurunathan

Chapter 5. Integration of Lignin Removal from Black Liquor and Biotransformation Process

Industrial discharge has tremendously increased inorganic pollutants in water bodies all over the world. Paper and pulp mill effluent is included in one of the most pollution-generating discharges containing complex chemical compounds such as lignin. For clean and healthy water resources, the recovery of lignin from wastewater from the paper and pulp industry is of high importance. On the other hand, these pollutants can be carcinogenic, due to the chlorine lignin and chlorine phenols that are formed along the process. The main focus of this study on precipitation of lignin from the black liquor (influent) is one stage followed by dewatering/washing to improve purity of lignin. Lignin valorization is an essential process for an advanced, sustainable, and economical biomass-based industry. However, converting lignin into value-added products remains a challenge due to its heterogeneity and irregular structure. Complex nature of lignin depolymerized by aromatic-catabolizing organisms to create “biological funnels” that receive heterogeneous aromatic substrates and convert them to a few products. Microbes such as bacteria and fungi are involved in the lignin degradation. Degradation of lignin through white-rot fungi may be helpful for the biotechnical applications like biopulping, biobleaching and pulp mill effluents treatment, and soil bioremediation. White-rot fungi specifically P. chrysosporium, also known as model fungus, and Coriolus versicolor are potential degradation against recalcitrant chromophoric material in bleach plant effluents. The abundance and renewability of lignin potentially converted to valuable bioproduct may eventually replace existing technology on manufacturing industries.
Krishnamurthi Tamilarasan, Periyar Selvam Sellamuthu, Baskar Gurunathan

Chapter 6. Role of Nanofibers in Bioremediation

Scarcity of pure water is a threatening issue worldwide; water is an essential need for human survival and all activities on earth. Effluent water from industries containing recalcitrant pollutants causes dangerous impacts to the environment and human health. In the current epoch, bioremediation is an alternative technology for decontamination of water systems by use of specific microorganisms and it can provide green, efficient, cost-effective, and sustainable remediation of water contaminants. Immobilized nanofibers possess enhanced catalytic activity, high stability, and very good reusability of novel nano-biocomposites which has remarkable potential for the treatment of water and wastewater. It also plays a major role in safe preservation of bioremediating bacteria for potential wastewater treatment applications. Nanofibers have become a popular carrier matrix for immobilization of specific microorganisms. Simple, versatile, and cost-effective properties of nanofibers made them a promising tool for microbial integration which enhances the bioremediation by efficient removal of contaminants such as dyes and heavy metals from wastewater. This chapter describes the immobilization of specific bacteria on electrospinning nanofibers and its application in bioremediation process.
Sekar Aiswarya Devi, Muthukumar Harshiny, Manickam Matheswaran

Chapter 7. Bioremediation of Industrial Wastewater Using Bioelectrochemical Treatment

Industrial waste/wastewater possesses a severe environmental threat to aquatic life. But, it also provides good potential sources for the removal and recovery of precious metal using various treatment processes. Several conventional treatment technologies such as physical, chemical, and biological (aerobic/anaerobic) methods used in the industries are an energy-consuming process and also expensive. Bioelectrochemical treatment system provides a novel platform to remove organic matter as well as recovery of heavy metal ions from various wastewater process streams. In bioelectrochemical treatment, organic matter is bioremediated by electroactive biofilms and coupled to cathode reduction to remove metal ions from the wastewater. This review summarizes the research on bioelectrochemical systems for bioremediation of organic matter as well as recovery of heavy metal ions from the wastewater. There are two different methods being discussed: firstly, removal of organic matters using different bioelectrochemical treatment systems; secondly, recovery of metal ions using abiotic and biotic cathodes in the system.
N. Samsudeen, Manickam Matheswaran

Chapter 8. Biosorption Strategies in the Remediation of Toxic Pollutants from Contaminated Water Bodies

Heavy metals, radioactive waste, hydrocarbon pollutant, and pesticides are some of the leading toxic pollutants in our environment. Challenges are faced in decontamination of these types of pollutants to soil and water for a long period of time. A number of methods such as membrane technology, electro-Fenton reaction, advanced oxidation process, and nanotechnology played a major role in removing toxic pollutants but difficulties are seen in degradation of toxic sludge, additional side reactions, high cost in initial installment and in maintenance, etc. Biosorption is a physiochemical metaprocess involving solid and liquid phases in which dissolved species to be sorbed. Low cost, high efficiency, and reusability of biosorbent are some of the advantages in biosorption. Biosorption involves removal of toxic pollutants by biomass. Some microorganisms are targeted for the removal of single pollutant alone. Algae, bacteria, fungi, yeast, waste materials from agricultural and food industries, etc., are used as biosorbent. Different mechanisms such as precipitation, absorption, adsorption, and ion exchange are combined with biosorption in order to treat toxic pollutants. This chapter provides collective ideas of various removal techniques in combination with biosorption and their applications to remediate water streams. This chapter also illustrates some of the problems faced during the biosorption activity and highlights the importance of improving the process for bioremediation in toxic pollutants.
P. Senthil Kumar, K. Grace Pavithra

Chapter 9. Bioremediation of Heavy Metals

Bioremediation technology is an effective and eco-friendly technology for removing toxic pollutants from the soil and aquatic environment. The lesser quantities of some heavy metals are important to humans and animals. However, the extensive usage of heavy metals for human purposes can change the geochemical cycles and biochemical balance. Due to this reason, the excess amount of toxic heavy metals like copper, lead, cadmium, nickel, and chromium is directly discharged into the soil and water bodies. The indiscriminate accumulation of heavy metals can be hazardous to the human life and aquatic biota. To overcome this problem, bioremediation technique has been developed for the treatment of heavy metals using biological agents like bacteria, fungi, algae, and plants. These biological agents can be used to change the metal bioavailability and toxicity in the soil and aqueous environment. The remediation of heavy metals in soil is further improved by the addition of organic amendments like biosolid, compost, and municipal solid waste, which is used as both nutrients and conditioner. Aim of this chapter is to investigate the role of microorganisms and plants to remediate the heavy metals and also to discuss the recent bioremediation technologies and methods for heavy metals in soil and aquatic environment.
P. Senthil Kumar, E. Gunasundari

Chapter 10. Pesticides Bioremediation

In the developing countries, the usage of pesticides in the production of crops, fruits, and vegetables increases the economic status which establishes the major success in this field. Although the pesticide is an important aspect of the agricultural practices, the vast handling of harmful pesticides is an ultimate concern to the air, water, soil, and public health. Due to high impacts on human health, their application has been limited and different scenarios are developed to clean up the stubborn pesticides at different contaminated sites. Biological techniques like bioaugmentation, biostimulation, biosurfactants, bioremediation contaminated sites are available for degrading the pesticides, but the last one was found to be a most preferred method to mitigate the hazardous pesticides. Bioremediation method uses biological agent like microorganisms to degrade the contaminants in the existence of sufficient nutrients and environmental conditions. Properties of polluted sites, temperature, pH, nature of the pollutants are important factors which play a major role in the bioremediation process. The intent of this chapter is to bring out the bioremediation technologies accessible for clearing of pesticides at contaminated sites; additionally, their fundamentals, advantages, limitations and the pesticides treated are also summarized.
P. Senthil Kumar, C. Femina Carolin, Sunita J. Varjani

Chapter 11. Application of Microbes in Remediation of Hazardous Wastes: A Review

Currently, pollution control, environmental management, treatment and recycling of wastes have become critical issues. One of the major reasons behind the growing environmental pollution is illegal disposal of waste. Due to the toxicity of waste, establishing efficient and environmentally friendly method to degrade and detoxify these wastes represent an important research challenge. Various physiochemical methods are applied all over the world for solid waste management. The application of microbes to degrade waste is gaining attention due to its environmental and economic benefits. The present review deals with application of microbes in bioremediation of hazardous wastes. This review also outlines the various factors that limit the use of microbial waste bioremediation technologies. Moreover, the prospects of waste valorization for the production of biopolymers, biofuels, biocompost and industrial enzymes are also discussed in the review article.
Moni Kumari, Pooja Ghosh, Indu Shekhar Thakur

Chapter 12. Phytoremediation Techniques for the Removal of Dye in Wastewater

Phytoremediation attempts to use plants and microbes associated with plant root systems to protect the environment by removal of pollutants in the form of inorganic and organic wastes. Phytoremediation is capable of treating pollutants of dye waste, which are derived from various sources. Adaptation in genetic levels is the basic attitude behind plants that able to manage the contaminants from polluted site. Various classifications of phytoremediation are discussed in this chapter. Among the various pollutants, textile dyes and effluents are identified to most predominant pollutants of our environment. Treatment of textile dyes using plant remains an unfamiliar area of research. Mechanisms of uptake of different dyes by plants have also been proposed. Selection criteria of plants for achieving high efficiency of treatment of dye contaminant wastewater have been projected. Use of Lemna minor L. plant with pond system in warmer regions has shown significant removal of Basic Red 46 dye. Different plants such as Tecoma stans var. angustata, Scirpus grossus, water hyacinth Eichhornia crassipes, aquatic plant Spirodela polyrrhiza have also been discussed for their potential of dye degradation. Consortium of Petuniagrandiflora and Gailardia grandiflora plants has been established for their role in dye degradation. Combined technology involving plant-associated micro-organisms with Medicago sativa L. and Sesbania cannabina Pers have also been proposed. Various impacts of azo dye on living organism have been discussed.
B. Bharathiraja, J. Jayamuthunagai, R. Praveenkumar, J. Iyyappan

Chapter 13. Phenol Degradation from Industrial Wastewater by Engineered Microbes

Over the centuries, a tremendous increase in human population has placed a demand for industrial growth, which enhanced the disposal of wastewater and resulted in developing a sustainable technology for wastewater treatment. Phenol and its derivatives are the most pondered substantial pollutants generated from pharmaceutical industries, basic organic chemical manufacturing industries, petroleum refineries, petrochemical industries, coal gasification operations, liquefaction process, tannery, pesticide manufacturing industries, and pulp and paper mills, which contain harmful pollutants that are toxic and carcinogenic in nature. Accumulation of phenol even at a lower concentration may be fatal to all living beings in the ecosystem. This chapter includes the overview of phenol pollution, deleterious effects of phenol in the ecosystem, biodegradation of phenols, and significance of engineered microbes for phenol degradation.
Ravichandran Rathna, Ekambaram Nakkeeran

Chapter 14. Insect Gut Bacteria and Their Potential Application in Degradation of Lignocellulosic Biomass: A Review

Lignocellulosic biomass is most abundant in the environment. Enzymatic breakdown of lignocellulose, an important component of common waste materials, can be an essential step toward mitigating the wastes and generating biofuel. The diverse microbial community is maintained within the insect gut as per their food habit, ecological niche. Certain insects have shown tremendous enzymatic potential as a feed on lignocellulosic materials for their nutrition. In this context, scientific community has become interested to explore different insect gut microbial diversity through the advent of new technologies. The present manuscript encompasses the potential role of insect gut bacteria, aspects of colonization, and role in degradation of lignocellulosic biomass. Further, the significance of potential bacteria for harnessing the enzymes and appropriateness of application in lignocellulosic wastes degradation is also discussed in this review.
Rajesh Kumar Prasad, Soumya Chatterjee, Sonika Sharma, Pranab Behari Mazumder, Mohan G. Vairale, P. Srinavas Raju

Chapter 15. Bioremediation of Volatile Organic Compounds in Biofilters

In India, 12 lakhs deaths per annum take place due to air pollution according to a report by Greenpeace organization. Volatile organic compounds are major air pollutants which are released into the environment through mobile sources, stationary sources, area sources, and natural sources. Stationary sources such as petrochemical and pharmaceutical industries release VOCs like toluene which is known to cause several health hazards including lung cancer. In addition to it, VOCs pollute air, soil, and water which are a growing environmental concern. Based on the concentration level of the VOCs, several removal techniques have been employed to combat VOCs. Non-biological methods such as ozonation, absorption, adsorption, incineration, catalytic oxidation, condensation, membrane separation are being employed. Several biological methods ranging from biotrickling filters to biofilters have been demonstrated, and they are found to be economical. The biofilters are simple to construct, easy to operate, and cost effective. Major advantage of this method is the pollutant is converted into biodegradable waste which can decompose within a moderate time frame, thus producing no secondary pollutants. In this chapter, biofilters, microorganisms, biofilter preparation and reaction mechanism are discussed. More emphasis was given on operation, processes, conditions, and stability of biofilters. The recent advancements in biofilters including application of foam for enhanced separation and the limitations of the biofiltration methods are also discussed. Future scope and summary of the chapter are given at the end of the chapter to provide an insight into biofilters research.
Margavelu Gopinath, Rose Havilah Pulla, K. S. Rajmohan, Parthasarthy Vijay, Chandrasekaran Muthukumaran, Baskar Gurunathan

Chapter 16. Bioremediation of Industrial and Municipal Wastewater Using Microalgae

The present scenario of increased population and industrial development leads to deterioration of freshwater and decreases the quality of water all over the world. This causes freshwater shortage in most of the area. Moreover, organic and inorganic substances released from various sources into the existing natural water bodies or environment lead to pollution. The primary and secondary treatment of wastewater had been introduced in many numbers of places to extinguish the easily settled material and to oxidize the organic matter in wastewater. But these methods were not found to be efficient because the effluent from secondary treatment is loaded with increased amount of inorganic nitrogen and phosphorus, and so, it leads to eutrophication and much more long-standing problems because of discharged heavy metals and refractory organics. On the other side, wastewater contains numerous ingredients, and interestingly, some of the compounds in the wastewater, like nitrogen and phosphorus, are identified as beneficial ingredients for microalgae cultures. Therefore, algal bioremediation can be considered as a feasible alternate technology for treating the wastewater in a cost-effective and assertable way compared to conventional water treatment process. These microalgal cultures are autotrophs, and they play a notable role in remediation of wastewater by their photosynthetic ability. A win–win situation of using microalgae in the bioremediation of industrial or municipal wastewater provides tertiary biotreatment of wastewater coupled with the production of potentially valuable biomass as bioresource for biofuel or high-value by-products. There is a mutual advantage in this method in which using wastewater for microalgal culture will minimize the use of freshwater, reduce the cost of nutrient addition, and also removal of nitrogen and phosphorous, and reduce CO2 emission. This chapter covered the overview of the role of microalgae in treatment of industrial as well as municipal wastewater.
Baskar Gurunathan, I. Aberna Ebenezer Selvakumari, R. Aiswarya, S. Renganthan

Chapter 17. Phytoremediation of Textile Dye Effluents

Water is the vital source to live and the textile dye effluent is one of the major contaminants present in the wastewater which is highly toxic to all form of lives. Though some effective various methods such as physical, chemical, and biological methods are available to remove the textile dye effluents, phytoremediation is the most economical, eco-friendly, easy to do to degrade the contaminates completely/partially present in effluent. The different plants are found with naturally inhabited metabolic pathways to utilize different dyes and some of the genetically engineered plants are also produced in order to effectively degrade the dyes and to sustain different environmental conditions. Symbiotic relationships between the plant and microbes are also used to help the plants to overcome different kinds of stress. The enzymes like oxidoreductases which are extracted from the plants have shown potent activity against dyes. The significant decrease in color, turbidity, conductivity, total suspended solids (TSS), total dissolved solids (TDS), chemical oxygen demand (COD), and biological oxygen demand (BOD) are taken as indicators of effectiveness of phytoremediation. Several researchers have done extensive studies in phytoremediation area in order to understand the exact mechanism to during treatment of effluents. This chapter mainly focusses on various phytoremediatic methods and its mechanism used in textile effluents treatments.
Shanmugaprakash Muthusamy, Dhilipkumar Govindaraj, Karthik Rajendran

Chapter 18. Role of Biosurfactants in Enhancing the Microbial Degradation of Pyrene

Pyrene is a high molecular weight polycyclic aromatic hydrocarbon (PAH) with a symmetrical structure, commonly found as a pollutant of air, water, and soil. Being one of the most abundant high molecular weight pericondensed PAH and having its structure similar to several carcinogenic PAHs is being used as a model compound to study the degradation of high molecular weight PAHs. Therefore, its removal from the environment is a challenging task for scientists. Pyrene has been found to be toxic to the aquatic microinvertebrate Gammarus pulex, and its quinone metabolites are mutagenic and toxic to organisms in the environment. This chapter mainly focuses on the microbial degradation of ecologically toxic pyrene by pure microbial cultures and microbial consortium, simultaneously emphasizing the role of surfactants in enhancing the degradation process.
Gauri Gupta, Avantika Chandra, Sunita J. Varjani, Chiranjib Banerjee, Vipin Kumar

Chapter 19. Bioremediation of Nitrate-Contaminated Wastewater and Soil

Water utilization is in a steep hike due to urbanization and population increase. On the other hand, pollution of fresh water due to human activities is increasingly a major concern as it affects economy and growth of a nation. Among various water pollutants, nitrogen compounds form a significant role in wastewater contamination due to increase in anthropogenic sources like agriculture. Release of nitrate into fresh water poses severe problems including eutrophication, methemoglobinemia, and other health issues. Thus, nitrate contamination in water and soil has become a growing environmental concern. According to USEPA standards, the maximum contamination level for nitrate is 45 mg L−1, and the same standard is adopted by the Bureau of Indian Standards (BIS). Among various technologies employed for treating nitrate-contaminated water, biological denitrification is one of the more versatile and promising methods widely being employed. The treatment of NO3 using bacteria referred as denitrification or bioremediation of nitrate has high separation efficiency. This chapter focuses on various biodenitrification processes, immobilization of microorganism, and different reactors employed for removing the nitrate from water. Different reactor designs ranging from fixed-bed reactors to biological aerated filters have been demonstrated for effective denitrification.
K. S. Rajmohan, Margavelu Gopinath, Raghuram Chetty


Weitere Informationen