eChapters

10.1 Introduction

As one ofthe oldest and most widely used renewable energy sources, hydropower generates electricity by using the natural flow of flowing water. Streams and rivers have been used for producing mechanical energy for thousands of years. Hydroelectric power plants are located near or on water sources since they derive their power from flowing water. The amount of energy that can be released in moving water depends on the volume of the water flowing and the elevation change from one point to another, often called head. Generally, hydropower plants can produce more electricity when there is more water flow and a higher head. 

Microalgae have long been recognized as good potential sources for biofuel production due to their relatively high oil content and rapid biomass production (Schenk et al., 2008; Hu et al., 2008). These photosynthetic organisms thrive in a variety of aquatic habitats, including lakes, rivers, oceans, and even sewage, demonstrating their adaptability to diverse environmental conditions. They can tolerate a wide range of temperatures, salinities, and pH levels, as well as varying light intensities and aquatic or desert conditions. Additionally, microalgae can grow independently or in symbiosis with other organisms, making them highly versatile for various cultivation systems (Mutanda et al., 2011). Algae are generally grouped into three major categories: Rhodophyta (red algae), Phaeophyta (brown algae), and Chlorophyta (green algae), and are further classified by size into macroalgae and microalgae. Macroalgae are large, multicellular organisms visible to the naked eye, while microalgae consist of microscopic single cells that can be either prokaryotic, similar to cyanobacteria, or eukaryotic, similar to green algae (Fields et al., 2014; Maltsev & Maltseva, 2021). Microalgae are capable of producing a wide array of valuable bioproducts, including polysaccharides, lipids, pigments, proteins, vitamins, bioactive compounds, and antioxidants. They grow at a much faster rate compared to terrestrial crops and can be cultivated on non-agricultural land using non-potable saltwater or wastewater, reducing competition with food crops and ensuring sustainability (Lee et al., 2014). This has made microalgae an increasingly attractive alternative feedstock for biodiesel production, which relies heavily on the high lipid content of microalgae. The majority of these lipids are stored in the form of triacylglycerols, a type of oil that is ideal for biodiesel production. Beyond biodiesel, microalgae can also be utilized in various other energy production pathways. Some microalgal strains can produce hydrogen gas under specific growth conditions, while algal biomass can be combusted like wood or digested anaerobically to produce methane biogas, which can be used for heat and power generation. Additionally, algal biomass can be processed into crude bio-oil through pyrolysis, further expanding its applications as a renewable energy source (Mumtaz et al., 2019).

Introduction 
Fossil Fuels like Coal, Coal product, Natural Gas, Petroleum, Crude Oil provide 80% of the world’s energy. However, burning them releases harmful pollutants, including carbon dioxide, nitrogen oxides and the sulfur oxides, contributing to global warming. To combat this, the World is shifting towards cleaner, renewable energy sources called biofuels. Biofuels are made from organic materials like plants and waste, offering several benefits: Renewable and Sustainable, Less greenhouse gas emissions, non-toxic [6]. Common biofuels include are: Biodiesel, Biogas, Bioethanol. These alternative fuels help reduce our reliance on fossil fuels, mitigating climate change and promoting a healthier environment. Biodiesel replaces fossil-based diesel/petrol made through Trans-esterifi cation process. The benefi ts include clean energy, renewable resources and the domestic production. Generations of biodiesel are: First Generation include Edible crops (Soybean, Corn, Sugarcane). Second Generation includes Non-edible biomass(Straw, Hay). Third Generation include Microalgae (70% yield). Fourth Generation include the genetically modifi ed algae and electro-biofuel. [2] Biodiesel production has changed over time. Initially, edible vegetable oils like soybean, corn, sunfl ower and palm oil were used. However this raised concerns: using valuable farmland for fuel instead of food, competing with food production, weather and soil quality affecting the crop yield , fertilizer use releasing harmful nitrous oxide greenhouse gas. To address these issues, focus shifted to non-edible oils and now Microalgae, offering; sustainable, climate-resilient production, no competition with the food crops, reduced greenhouse gas emission, higher oil yield. Microalgae -based biodiesel is the future providing a cleaner, more effi cient alternative.[4]

Introduction 
Fuels are essential to human existence and account for 70% of the world’s energy use. The demand for fossil fuels is rising daily due to the ongoing global population boom and has now reached a crisis point. The world’s current reserves cannot keep up with the projected 40% rise in demand between 2010 and 2040 [1]. According to Energy Information Administration (EIA) statistics, the world’s fossil fuel sources will run out in fewer than 50 years [2]. In addition, burning fossil fuels and living in an industrialised environment have released large amounts of carbon dioxide (CO2), carbon monoxide (CO), sulphur dioxide (SO2), nitrogen oxides (NOx), as well as a significant number of potentially toxic compounds into the atmosphere. This has severely degraded the natural resources that are currently available, including fossil fuels. The human and natural ecology have suffered significant damages as a result of the effects of global warming in recent years [3]. As a result, cutting CO2 emissions is crucial to preventing the negative effects of global warming. Therefore, there has been a greater focus on the improvement of CO2 capture and sequestration systems to significantly lower CO2 emissions from a variety of sources, including vehicle exhaust emissions and industrial flue gas [4] . Fuel production needs to be sustainable in terms of the environment and the economy, meaning it needs to be able to reduce CO2. It is critical to find inexpensive, sustainable, and clean energy options in order to handle the current circumstances. Currently, several traditional renewable energy sources, such as solar, biofuels, hydroelectric, geothermal, or wind are being used with varying degrees of success and detriment. Biofuels are sustainable and renewable energy sources that have emerged as a superior alternative to traditional fossil fuels in energy production. Biofuels have a lot of potential because they are abundant environmentally favourable renewable resources and their production is expanding globally, even though they are still more expensive than fossil fuels [5]. Researchers are actively investigating biomasses as a means of obtaining energy from renewable sources. It is commonly known that through a process called photosynthesis, plants can transform sun energy into chemical forms. Microalgae are fast-growing microorganisms that develop 100 times quicker than terrestrial plants. Their photosynthetic efficiency is also higher (10–50 times greater than terrestrial plants) among biomasses [6]. In less than a day, they can double their biomass. Unicellular microalgae, in contrast to plants, do not divide substantial amounts of biomass into supporting structures like stems or roots, which are costly to create energetically and frequently challenging for harvesting and processing to produce biofuel. Furthermore, they have the ability to adapt to harsh aquatic environments and economically absorb helpful substances. Moreover, 1 kg of microalgae biomass is produced by microalgae cells that fix 1.8 kg of CO2 and have a 50% carbon content [7]. Microalgae can be grown on terrain that is inappropriate for food production because of their high total yield and hence small land use footprint [8]. Microalgal species including Scenedemus sp., Chlorella sp., and Botryococcus sp.; are common, easier to grow than other species and may have higher lipid contents [9].

1.    Introduction    360
2.    Feedstocks for Biodiesel Production    361

    2.1.    Fats and oils, 362
    2.2.    Alcohols, 363
    2.3.    Catalysts and neutralizers, 367

1.    Introduction    468

2.    Biofuel Cell    470

    2.1.    Microbial-based Biofuel Cells, 471
        2.1.1.    Microbial bioreactors producing H2 for conventional fuel  cells, 475
        2.1.2.    Microbial fuel cells producing electrochemically active metabolites in  
                the anodic compartment, 476
        2.1.3.    Microbial fuel cells operating in the presence of artificial electron relays, 477
        2.1.4.    Microbial fuel cells producing electricity during wastewater treatment, 483
        2.1.5.    Microbial fuel cell producing  electricity from acetate or butyrate, 484

1.    Introduction    302
2.    Raw Materials for Alcohol Production    304

    2.1.    Sugary substrates, 306
    2.2.    Starchy residues (cereal grains), 309
    2.3.    Cellulosic materials (crop residues), 314

3.    Microorganisms for Alcohol Production    316

    3.1.    Comparision of ethanol production by bacteria and yeasts, 318

1.     Introduction    424

2.    Conventional Methods of Hydrogen Production    426

3.    Biological Methods of Hydrogen Production    429

    3.1.    Hydrogen production by biophotolysis of water, 430
        3.1.1. Photolysis by cyanobacteria (Blue green algae), 430
            3.1.1.1. Nitrogenase dependent hydrogen production, 434
            3.1.1.2.  Hydrogenase-dependent hydrogen production, 437
            3.1.1.3.  Factors affecting  hydrogen production by cyanobacteria, 440
            3.1.1.4.   Bioreactors for cyanobacterial hydrogen production, 443
            3.1.1.5. Future prospects for cyanobacterial hydrogen production, 446

1.    Introduction    392

2.    Landfill Gas    393

3.    Biogas    394

    3.1.    Benefits of biogas, 394
    3.2.    Potential of biogas, 395
    3.3.    Biogas production system, 396
        3.3.1.    Raw materials, 396
        3.3.2.    Biogas technology, 398
        3.3.3.    Process of anaerobic fermentation for methane generation, 400
        3.3.4.    Conditions for anaerobic fermentation, 404
        3.3.5.    Sludge-algae-methane system, 407
        3.3.6.    Biogas plant, 408

1.    Introduction    272
2.    Alcohols    273

    2.1.    Methanol, 274
    2.2.    Ethanol, 277
    2.3.        Butanol, 283

3.    Biodiesel    284
4.    P-series fuels

Abstract

Microorganisms inhabiting in the rhizosphere play a vital role in ecosystem functioning. Rhizosphere is an area around the root surface where pathogenic and beneficial microorganisms repose and influence the plant growth and health. These microbial groups of bioagents found in the rhizosphere include bacteria, fungi, nematodes, protozoa, algae and micro-arthropods. Because of their rich diversity, complexity of interactions and numerous metabolic pathways, microbes are an amazing resource for biological activity. These microorganisms require organic matter for their growth and activity in soil and provide valuable nutrients to the plants and hence maintaining the plant health. The most promising fields for the use of bioinoculants are agriculture, horticulture and forestry. There are many reports on the inoculation of bioagents in agriculture and horticulture crops but only a few reports are available in forestry. This article is an overview on various bioinoculants which are used during inoculation and a compilation of scattered reports of bioinoculants in forestry only.

1. Introduction
Pharmaceutical pollution has emerged as a significant global concern, raising alarms about its potential impacts on ecosystems and human health. The journey of pharmaceutical compounds from their point of use to contamination of water bodies reveals a complex and interconnected web of anthropogenic activities. From manufacturing plants to individual households, these pollutants persistently infiltrate aquatic systems, creating a growing

Abstract

Now a days, the public has become more sensitive towards the protection of the environment and general awareness has increased about the adverse effects of industrial effluents contaminate with various pollutants, including dyes on the environment. Dyes are an important class of synthetic organic compounds used in many industries, especially textiles. Consequently, they have become common industrial environmental pollutants during their synthesis and later during fiber dyeing. Textile industries are facing a challenge in the field of quality and productivity due to the globalization of the world market. The dyes, which are widely used in textile industries when left in water bodies without any treatment cause environmental pollution and in turn are toxic, carcinogenic and mutagenic. The efficient treatment of the sludge from the industries is not economical and a challenging task. Currently, a number of different technologies and methods such as biological, physical and chemical are widely used for the removal of dyes. The treatment technologies for the removal of textile dyes from the textile wastewater found that over the past two decades interestingly focused on biodegradation methods such as microbial decolourization, enzymatic decolourization, adsorption by microbial biomass (living or dead) and bioremediation systems as a better alternative as the available physico-chemical methods.

1.    Introduction    129
2.    Soil Microbiology    129

    2.1.    Bacteria, 130
    2.2.    Fungi, 132
    2.3.    Algae and Cyanobacteria, 132
    2.4.    Protozoa, 132
    2.5.    Viruses, 135

3.    Water Microbiology    133
4.    Microbial Associations    133

    4.1.    Neutral interactions, 133
    4.2.    Positive interactions, 133
    4.3.    Negative interactions, 133

2.1 Introduction 
The world is encountering a severe power and environmental crisis. Adopting sustainable progress is the best means to protect our environment and maximise the use of available resources. The urgent issues, encompassing diverse types of pollution and carbon emissions, highlight the necessity to shift towards renewable energy sources. This shift is essential for diminishing our dependence on fossil fuels, addressing the on-going challenges regarding climate change, and confronting the exhaustion of current energy reserves. Furthermore, mitigating water pollution is an essential component of ensuring ecological sustainability [1,2]. Water supplies are rapidly being contaminated due to diverse contaminants including heavy metals, and harmful chemicals. While industrialization is critical for societal growth, it is critical to recognise the negative environmental consequences caused by numerous processes that emit hazardous substances. Improper disposal of untreated wastewater can negatively impact ecology and biodiversity [3]. As a result, it is critical to use environmentally friendly and sustainable treatment methods that adhere to green development principles. This will bolster industrialization efforts while upholding water pollution safeguards for recovery and reuse. Given the prevailing energy crisis, traditional wastewater treatment facilities have become financially unsustainable due to their high energy consumption. Traditional wastewater treatment is both costly and demands substantial energy resources. Furthermore, these approaches fall short of efficiently eradicating recalcitrant organic waste, heavy metals, and other persistent contaminants. Moreover, many of these treatment processes require regeneration. Microbial fuel cell (MFC) technology has emerged as an ecofriendly treatment option capable of effectively eliminating stubborn organic pollutants and heavy metals over the long term. Microbial fuel cells are chosen over other current treatment methods because to their reduced energy needs and lower chemical usage [4,5]. In addition to lowering energy usage, MFCs possess the ability to produce ample bioenergy, which can help alleviate the energy shortage. This provides a cleaner alternative for generating renewable energy in favour of sustainable development and environmental protection as depicted in Figure 2.1.

The increase in population and global industrialization has led to environmental pollution, which is a significant threat to the health of the ecological system. Different measures are recommended to remediate polluted areas effectively. The applications of nanotechnology in medicine, cosmetics, sports, textiles, and pharmaceuticals have increased over the years. Another approach to remediate the adverse effects of pollutants on the environment is by utilizing nanotechnology for contaminant remediation. Biogenic nanoparticles are tiny particles produced by biological entities such as fungi, bacteria, yeast, and algae. These biogenic nanoparticles are efficient in removing pollutants like heavy metals, pharmaceutical waste, dyes, and hydrocarbon waste. 

1.    Introduction    174
2.    The Thermodynamic and Mechanistic basis of Cellular Metabolism    174

    2.1.      Adenosine triphosphate, 175
    2.2.    Coenzyme A, 176
    2.3.    Modes of ATP synthesis, 177

3.      Components of Electron Transport Chain    181

    3.1.    Electron carriers in ETC, 182
    3.2.    Complex I - NADH dehydrogenase (NADH coenzyme Q reductase), 185
    3.3.    Complex II - Succinate - coenzyme Q reductase, 187
    3.4.    Complex III - Coenzyme Q - cytochrome c reductase, 187
    3.5.    Complex IV - Cytochrome c oxidase, 188
    3.6.    ATP synthese, 188

Abstract
 
Opencast mining destroys the original land ecosystem and microbial community due to mining and stockpiling of mine rejects on adjoining land, which is a matter of great environmental concern. Mining creates formation of wastelands, formation of gullies, ravines, overburdens, reduced water infiltration and increased runoff. Reclamation of mined out areas is often difficult due to its chemical, physical and biological traits. Absence of topsoil is the most common feature of the mine spoils dumps. Arbuscular mycorrhizal fungi (AMF), the synonym of VAM fungi, are important microbes of soil that form symbiotic association with most of the terrestrial plants on the earth. Observations led to use of legume microsymbionts as biological substitutes for fertilizers. AMF diversity increases with species diversity of plants as the potential number of association increases. Dominant arbuscular mycorrhizal fungi can prevent the invasion of non-mycorrhizal plants on land where they have established symbiosis and promote their mycorrhizal host.

Abstract

Microbiological synthesis of nanoparticles has emerged as rapidly developing research area in nanotechnology across the globe with various biological entities being employed in production of nanoparticles constantly forming an impute alternative for conventional methods. Simple prokaryotes to complex eukaryotic organisms including higher plants are used for the fabrication of nanoparticles. In the present article, the synthesis of important plant nutrients like Mg, Zn, Ag, Au, Ti, P and Fe nanoparticles from different fungal species, their characterization and application potential of nanonutrients in agriculture is elaborately discussed.

The basic methods for wastewater sewerage (collection, treatment, and disposal) are as follows:

• Off-site sewerage
• Separate sewerage system
• Combined sewerage system
• On-site sewerage

Many nations have implemented separate sewage systems that transmit sewage and storm water through separate pipelines in order to separate the two. Storm water often does not contribute to a wastewater treatment facility (WWTP). Domestic sewage contains 99.9% or more water. The remaining portion is made up of bacteria