Growing need for energy for sustaining increasing population has resulted in overexploitation of natural resources and over use of fossil fuel-based energy sources (coal, oil and gas). The consumption of non–renewable resources such as coal, petroleum and natural gas has increased tremendously resulting in environmental problems and climatic changes. Emission of greenhouse gases and other environmental concerns have increased. The decline in the quantity of non-renewable resources has generated the search of alternate energy sources. Switch to alternate sources of energy and fuel can be a sustainable option to this problem. Solar, tidal, geothermal, wind are some of the renewable sources of energy that are being focused to curtail the energy crisis and ensure sustainability for environment. A framework based on fulfilling the SDGs need to be developed which can contribute for more profitable, responsible path of economic growth and development.

Waste management has become a major global concern. The rapid rise in the rate of population has increased the generation of waste at a tremendous pace. Improper disposal of agricultural, household, municipal and industrial wastes can pose a threat to the health of living beings and the environment. Industrial waste, in particular, is highly hazardous as it contains toxic chemicals and metals. Many methods of waste disposal have been adopted, but most of them produce various kinds of after-effects, therefore, biological methods have been adopted because of their eco-friendly and sustainable nature. Sustainable waste management aims to minimize the amount of waste generation. Waste is treated in a proper way, involving the steps such as segregation, recycling and reuse. Biotechnological methods such as composting, biodegradation of xenobiotic compounds and bioremediation have been tried. These methods have proved useful in treating waste in an eco-friendly way. More research studies need to be carried out to standardize the method for the proper treatment of waste so that environmental sustainability can be achieved. 

Increased requirements for food and commodities have generated immense pressure on land resources. Landforms and forest areas have been converted to agricultural lands and rehabilitation areas to support the needs of a growing population. Owing to these changes, an urgent need for afforestation and land restoration has been generated. Various methodologies have been tried to restore the degraded land and increase the forest cover. Clonal propagation aiming at rapid multiplication and large-scale production of plants via selected clones has been successfully implemented. This approach has proved useful in raising commercial plantations. The use of biotechnological approaches such as molecular markers and advanced breeding programmes proved useful in raising clones for achieving afforestation and land rehabilitation on a large scale. The present chapter provides a detailed account of biotechnological techniques and processes that have played a significant role in afforestation and land rehabilitation. 

Wastewater contamination is increasing day by day because of increase in industrial operations and anthropogenic activities. Wastewater is a by product of industrial and domestic operations which is directly disposed into the environment and contain large amount of toxic materials harmful for human, animals as well as environment. Wastewater coming from industries is highly contaminated hence its recovery is a major concern. Developing countries and less developed countries generate large amount of wastewater in comparison to developed countries. Biotechnology provides best solution to get rid of this problem. Different technique/methods such as use of activated sludge, trickling filters, biosorption, bioaccumulation, use of nanoparticles play a major role in treatment of water. Role of microorganisms via microbial fuel cells and membrane biofilm bioreactors have also been used for removing metals present in wastewater. This chapter aims to provide complete information about biotechnological approaches for wastewater treatment in a cost- effective manner along with complete removal of sludge and toxic compounds. 

Pollution and unsustainable use of natural resources such as land and soil has resulted in their destruction. Restoration of degraded land and soil is essential for maintenance of essential ecosystem services such as preservation of biodiversity, nutrient/water cycling and meeting the food requirement for living beings. Bioremediation has appeared as technology with high potential for restoring damaged soil and degraded lands. Biotechnological techniques such as development of efficient microbial consortia with an enhanced capacity to remove various contaminants from soils and improvement in nutrient retention in soil have opened new prospects in bioremediation with an aim to recover productive capacity of soil. The techniques such as bioventing, bioaugumentation, biosparging have also proved useful in restoring degraded and non-productive soils to a great extent. The biotechnological techniques, thus can act as an ecofriendly method for remediation, restoration and reclamation of degraded/damaged soils.

Nanotechnology plays an important role in monitoring, preventing, and remediating environmental pollution. Nanomaterials are used in the detection and removal of contaminants such as heavy metals, organic pollutants (aliphatic and aromatic hydrocarbons), and biological agents such as viruses, bacteria, and parasites. Nanomaterials act as good adsorbents, catalysts, and sensors due to their large specific surface areas and high reactivities. Physicochemical properties, such as large surface area, facilitate easier biodegradation/remediation of environmental contaminants. Carbon nanomaterials, namely carbon nanotubes, graphene, graphene oxide, and zero-valent iron nanoparticles, have shown great potential for the removal of heavy metals and organic contaminants from water and soil. Hence, nanoremediation represents an innovative approach to safe and sustainable remediation of environmental contamination. 

The planet is dealing with a major problem of environmental pollution. Year after year, this problem worsens, causing harm to our planet. To combat the major environmental issues, various technologies have been developed over the years. The use of nanomaterials in environmental management is becoming more common. Nanomaterials are increasingly being used to clean the air, purify water, decontaminate soil, and detect pollution. Nanotechnology has emerged as a technique for cleaning up pollution and monitoring degradation of environmental sectors such as air, water and soil. Hence nanotechnology can contribute to the sustainability of the environment. This chapter discusses the use of nanomaterials in the monitoring of air pollutants, organic contaminants and other environmental pollutants, as well as the various methods involved in the production of nanoparticles. 

Presence of micro pollutants and pathogens in water has become a concern worldwide. Micropollutants such as pharmaceutically active compounds, personal care products, organic compounds and pathogens/microbes (viral, bacterial and protozoa) pose a threat to humans. Nanotechnology has proved effective in developing strategies for the treatment of contaminated water. Nanomaterials have found application in the removal of different categories of pollutants, from water. The properties such as high reactivity and effectiveness establish nanomaterials as ideal materials suitable for treatment of contaminated water/wastewater. Nanomaterials such as carbon nanotubes, graphene-based composites and metal oxides, have shown potential to remove dyes, pathogens from wastewater. Research efforts are required to develop an eco-friendly, economic and sustainable technology for the removal of micropollutants and biological agents such as microbes using nanomaterials.

Magnetic nanoparticles (MNPs) possess inherent properties that help them in improving the quality of the environment via the detection, remediation, and removal of pollutants and contaminants. The properties such as high reactivity, high surface-to-volume ratios, superparamagnetism, large surface area and biocompatibility are responsible for the extensive use of magnetic nanoparticles in environmental remediation. MNPs act as adsorbents or catalysts and help in the removal of contaminants from environmental matrices. High pollutant removal efficiency of magnetic nanoparticles can be exploited in framing low-cost-effective technologies for environmental remediation. 

Nanotechnology has emerged as an alternative to conventional water treatment methods that involve high costs and processes. Nanomaterials offer great potential for cleaning wastewater. Various nanomaterials have shown the potential to remove pollutants such as organic and inorganic content, and toxic heavy metal ions from wastewater. Nanoparticles with nanofibers and carbon nanotubes form an important part of ultrafiltration membrane, osmosis, sorption, advanced oxidation process, water remediation as well as disinfection processes. The rate of removal of contaminants from wastewater depends upon the physical and chemical characteristics of the nanomaterial, the contaminant, and wastewater

Bioplastics are plastics that are manufactured from biomass. These polymers have become increasingly popular as a means of conserving fossil fuels, lowering CO2 emissions and minimising plastic waste. The biodegradability of bioplastics has been highly promoted, and the demand for packaging among merchants and the food industry is fast rising. It also has a lot of potential applications in the biological and automobile industries. The plastic on the market is extremely dangerous because it is non-biodegradable and harmful to the environment. As a result, the production and usage of biodegradable polymers are becoming increasingly popular. Some of the more recent formulations, partially as a result of third-party certifications, are more compliant than the initial generation of degradable plastics, which failed to achieve marketing claims. Many “degradable” plastics, on the other hand, do not degrade quickly, and it is unclear whether their use will lead to significant reductions in a litter. Biodegradable polymers, such as poly(lactic acid), are seen as viable replacements for commodity plastics. In seawater, however, poly(lactic acid) is practically non-degradable. Other biodegradable polymers' degradation rates are further influenced by the habitats they wind up in, such as soil or marine water, or when utilised in healthcare equipment. All of these aspects are discussed in detail in this chapter, including bioplastic types, applications, production, degradation, problems in landfills and sea water, fermentation, synthesis, and sustainability. This chapter, taken as a whole, is intended to help evaluate the possibilities of biodegradable polymers as alternative materials to commercial plastics.

The diminishing quantity of fossil fuels and environmental degradation lead to the search for renewable and environmentally friendly fuels that can substitute petroleum. The burning of petroleum products releases gases that pollute the environment, hence need for alternate fuels was realized. Biofuels such as biodiesel and bioethanol derived from food crops, biomass, algae, vegetable oil, animal fats, or lignocellulosic materials are renewable, biodegradable and non-toxic. They possess low quantities of sulfur, polycyclic aromatic hydrocarbons, and metals and are considered eco-friendly. Biotechnological methods have been adapted to increase the production of crop plants that are used in the production of biofuels. Genes encoding for enzymes that degrade lignin, an important component of food crops,have also been inserted in food crops so that processing can be made easier for getting increased production of biofuels. 

Heavy metal contamination has affected various life forms on earth due to their toxic, carcinogenic and bio-assimilative nature. Heavy metals are rapidly transported by various water bodies in our environment. Thus, the remediation of heavy metals in water bodies is essential for sustaining our ecosystems. The treatment technologies available for treating the heavy metals undergoing dynamic biochemical transformations in the environment are a challenge as well as an opportunity for developing alternate cost-effective technologies. Adsorption has emerged as an environment-friendly and cost-effective technology. Biochar, a sustainable and low-cost adsorbent, has shown encouraging results for the remediation of these environmental contaminants. It stands out as a promising adsorbent due to chelating functional moieties apart from high surface area and porosity. These physicochemical attributes of biochar can be modulated using various physicochemical treatments to achieve higher heavy metal removal efficiencies. Biochar is a carbon-neutral material, which can be regenerated and disposed-off easily in an adsorption-based remediation process. This chapter brings out the modifications characteristic of biochar, a comparative statement of properties vis-a-vis biochar and their use in the adsorption of heavy metals, and various mechanisms accounting for their removal.

Green technologies provide an eco-friendly and sustainable alternative to conventional technologies. Conventional technologies used for combating pollution show certain limitations and drawbacks. Green technologies have been accepted worldwide for their advantages, such as easy availability, less environmental harm and sustainability. In recent years, solar, wind, geothermal energy, and alternate fuels, such as biogas and biodiesel, have emerged as eco-friendly alternatives to conventional energy sources and fuels. Green technologies, such as developing eco-friendly and recyclable products, have restricted the release of greenhouse gases, generation of waste, and exploitation of natural resources to a great extent. Green technologies thus provide a sustainable option to prevent environmental degradation and over-exploitation of natural resources. Carbon-neutral alternatives have the potential to meet the needs of present and future generations. The production of clean energy is one of the major approaches to get a sustainable environment. Developing clean and environmentally friendly carbon-neutral alternatives can prove useful in meeting the needs of the fuels of present and future generations. 

Pollution in various sectors of the environment has produced a threat to human health and aquatic ecosystems. Biosensors play an important role in the detection of toxicants such as heavy metals. Efforts have been made to develop sensitive and efficient sensors for monitoring the presence of contaminants in the environment using nanotechnology and bioengineering techniques. Biosensors, in particular, help in monitoring the presence of pollutants in the environment, protecting our environment. Enzyme, DNA, imuno and whole cell-based biosensors have been developed and work depending on the reaction type, transduction signal, or analytical performance. Advantages such as specificity, low cost, ease of use, and portability establish biosensors as an efficient technique that can be used to detect the presence of various inorganic and organic contaminants. 

Modern agriculture is almost entirely reliant on the supply and utilization of agrochemicals, such as fertilizers, pesticides, and insecticides, to maintain and boost agriculture productivity. Heavy use of chemical fertilizers has resulted in numerous adverse effects on the environment and human health. Biofertilizers have emerged as an eco-friendly, inexpensive, and renewable alternative to restore, enhance, and maintain soil fertility, soil health, and crop yield. Biofertilizers are beneficial microbes, including plant growth-promoting rhizobacteria, mycorrhizal fungi, cyanobacteria, and their symbionts. Hence, the importance of biofertilizers in soil management practices for soil and crop sustainability needs to be highlighted in light of their multiple benefits, including augmenting nutrient availability in the rhizosphere, increasing nutrient uptake and recycling, supplementing soil water holding capacity, production of plant growth regulators, and soil reclamation. The challenges regarding the large-scale utilization of biofertilizers need to be emphasized to achieve sustainability in agricultural soils.