Environmental Biotechnology: For Sustainable Future

Several studies have reported that open municipal dumpsites in developing countries are acting as a major source for a wide variety of pollutants. In developing nations, many dumpsites are located in the urban centers or even within the residential boundaries. Contaminants released during incomplete combustion of municipal solid waste have profound adverse impact on human health and the environment. Hence there is an urgent need to identify a low-cost technique to decontaminate such heavily polluted sites. In this chapter, we have reviewed several papers and discussed how different types of engineered biochars can be effectively used to adsorb contaminants from dumpsite soil. Biochars are basically carbon-rich solids treated by high-temperature pyrolysis. Biochars are obtained by heating biomass in presence of less oxygen or in anaerobic conditon. Properly pyrolysed mixtures of organic and cellulosic wastes are capable of adsorbing a wide variety of organic contaminants from wastewater, sludge and soil prior to the release or disposal in engineered landfills. Biochar produced from waste organic material such as coconut shells, sugarcane bagasse and straw has been reported with high adsorption capacity. Because locally produced waste organic material can be utilized for production of these low-cost adsorbents, they are especially attractive for remediation and treatment systems in developing countries. Pyrolytic temperature is believed to be the most important factor affecting the sorption capacity of biochar, followed by grinding to increase the surface area. Holding and adsorption capacity of the biochar for treating contaminants in soil could be a limiting factor of these materials. Some studies have shown that less than 5–7% (m/m) mixing of biochar and soil resulted in higher water retention capacity leading to increased potential for biodegradation. We therefore suggest that improved low-cost processing methods should be investigated so that biochar can be exploited as an adsorptive medium for remediating and treating contaminated soils in these regions.

The requirement and need of novel techniques to speed up the sanitization of polluted and adulterated sites and reduction in the expenses of these methods is a growing concern. The application of nanoparticles, predominantly the iron nanoparticles, as a pioneering and inventive technique to decontaminate the adulterated sites has received attention and consideration in recent times. Though, all over the world, many research studies have been carried on nanoparticles, diminutive level of knowledge is realized about their performance, actions, and conduct in the soil and in aquatic habitats, their adsorption on soil mineral particles, and communication with soil microbes.

Industrial sectors, which are involved in the manufacturing of display, optical and photonic products, semiconductors, memory and storage devices, nano-biotechnology equipment (energy aspects), and health care goods, generate most of the products that contain nanoparticles. On the other hand, nanotechnology is a technique which has been employed as an environmental know-how to guard the nature through prevention, handling, curing, and cleanup of pollution. In this chapter, we have focused on the environmental toxicant cleanup and discuss a background and overview of the existing practices related to the remediation. The research findings; social issues; probable environmental, human health, and safety repercussions; and future thoughts for remediation using nanotechnology are also discussed. Here, we also discuss nanoscale zerovalent iron in some detail. The technique of nanoremediation has the capacity to lessen the total costs of decontamination at the bigger polluted sites. Moreover, the purpose of this technique is also to reduce the cleanup duration, eradicate the treatment requirement and dumping of the contaminated soil, and also lessen contaminant amount to almost zero. Further, we believe that suitable evaluation of nanoremediation approaches, especially the large-scale environmental studies, also need to be addressed to avoid and counteract any probable hostile environmental effects.

Escalated industrialization, inappropriate waste management practices, mining, landfill operations, and application of sewage sludge have caused excess contamination of aquatic and terrestrial ecosystems. As a consequence, human beings pose serious threats to life-supporting resources, i.e., air, soil, and water. Heavy metals and pesticides are a special class of contaminants having wide variety of effects. When the contaminated lands are used for agriculture practices, contaminants like heavy metals and pesticides get transferred from soil to food chain which leads to bioaccumulation and biomagnification. Phytoremediation (a technique that exploits plants ability to lessen, eradicate, degrade, or immobilize the environmental contaminants, with the aim of restoring the contaminated area) is gaining advantage over other conventional treatment techniques being economical, environmentally sound, and aesthetically acceptable. Conventional approaches for cleanup and restoration of heavy metals and pesticides from contaminated environment have some unavoidable precincts like high cost and creation of secondary pollutants. Many aquatic and terrestrial plants such as Eichhornia, Pistia, Lemna, Salvinia, Typha, Hydrilla, Ricinus, Brassica, Arabidopsis, Vetiver, Solanum, etc. are capable of accumulating heavy metals and can be used as agents for eco-restoration of degraded ecosystems. Further, biosorption has also emerged as an innovative, eco-friendly, cost-effective, and probable substitute for the removal and/or recovery of inorganic contaminants from aqueous medium. Biosorption can be applicable over wide range of temperature and pH, with rapid kinetics of adsorption and desorption and low capital and operation cost. Even, biological biomass can again be regenerated for reuse.

Anaerobically digested distillery effluent is a mixture of complex organic and inorganic pollutants which is composed of several plant sterols which do not only affect the water quality but also aquatic flora and fauna. Research has revealed the adverse effects of post-methanated distillery effluent (PMDE) on the seed germination and plant growth of Phaseolus mungo even at lower concentrations. Studies have also showed the adverse effect on soil fertility by inhibiting the nitrogen-fixing bacteria and root nodulation. The major colorant of distillery effluent is melanoidin, reaction product of amino-carbonyl compounds at elevated temperature in the sugar industries and distilleries due to condensation reaction. Due to its high solubility in aquatic ecosystem and negative charge, it makes complexation with all the humic substances and heavy metals in the environment. Therefore, the decolorization and degradation of PMDE is still a global challenge due to its complexity. The physical, chemical, and biological techniques have been attempted for its detoxification and color removal but still warranted for its feasible application. Manganese peroxidase (MnP) and laccase have been reported as key enzymes from fungi and bacteria. During the degradation process of PMDE, different metabolic products through GC-MS/MS analysis have also been characterized. The integration of bacterial treatment with constructed wetland plant treatment (Phragmites communis, Typha angustifolia, and Cyperus esculentus) technique has been reported recently as an effective approach for decolorization and degradation of PMDE. The major challenge of PMDE biodegradation and decolorization is its high total dissolved solids (TDS) containing complex organic pollutants including heavy metals. The high TDS is a result of precipitation of metal sulfides during anaerobic digestion of distillery spentwash due to complexation of heavy metals and sulfates which impose inhibitory effects on the microorganisms, consequently inhibiting the biodegradation process. Several complex organic pollutants present in PMDE have been also reported as endocrine-disrupting chemicals (EDCs) which directly affect the aquatic and terrestrial ecosystems.

Metals naturally exist in the crust of the earth, and their compositions vary among different localities, resulting in structural disparity of surrounding concentrations. Some heavy metals are much important in trace amounts in respect to living organisms related to their metabolic activities. High solubility of various heavy metals changes them into extremely toxic and perilous contaminant of water and soil when discharged by many industrial activities. When these metals are released into the environment, they can be leached into the underground waters, depositing in the aquifers, or run off into surface waters and soils thereby resulting in water and soil pollution. Thus, heavy metals become a potential contaminant for environment that can partake in trophic transfer in food chains. The toxicity of heavy metals mainly depends upon its relative oxidation state, which is responsible for physiological bio-toxic effects. When these metals enter into the living organisms, they, combine with proteins, enzymes, and DNA molecules, form highly stable bio-toxic compounds, thus altering their proper functioning and obstructing them from the bioreactions. Arsenic, chromium, cadmium, and lead are highly toxic and produce mutagenic, carcinogenic, and genotoxic effects. Hence, this chapter is focused on occurrence and allocation of heavy metals, their toxicological impact on environment, and their possible eco-friendly remedies for green and healthy environment.

The rhizosphere is the region around plant roots where maximum microbial activities occur. In the rhizosphere both beneficial and harmful activities of microorganisms affect plant growth and development. The mutualistic rhizospheric bacteria which improve the plant growth and health are known as plant growth-promoting rhizobacteria (PGPR). They are of much importance due to their ability to help the plant in diverse manners. PGPR such as Pseudomonas, Bacillus, Azospirillum, Azotobacter, Arthrobacter, Achromobacter, Micrococcus, Enterobacter, Rhizobium, Agrobacterium, Pantoea, and Serratia are now very well known. Application of PGPR as bioinoculants/bioformulations is found to be very effective in enhancing crop productivity in a sustainable way. The use of PGPR in agriculture is also ecologically important as the synthetic chemicals used in agriculture are a severe threat to agroecosystems.

Increasing agro-productivity for feeding growing world population under present climatic scenario requires optimizing the use of resources and adopting the sustainable agriculture methods. This can be achieved by using plant-beneficial bacteria. Target of achieving sustainable agriculture implies the use of varieties that are resistant to disease and tolerant to stress and having desired nutrition value. This can be effectively achieved through the use of rhizospheric microflora including bacteria, fungi, algae, etc. Among these, plant growth-promoting rhizobacteria (PGPR) have been seen as reliable and most promising bioinoculants for promoting plant growth and controlling phytopathogen without causing environmental deterioration. Application of PGPR as bioinoculants can help in achieving the target of global agricultural productivity to feed the world’s booming population, which is expected to become 9 billion by 2050. However, to be useful and effective bioinoculants, PGPR strains should be competent in their habitat, safe to the environment, helpful in plant nutrition and biocontrol, compatible with useful soil rhizobacteria, and tolerant to a variety of stress factors and show broad spectrum activity. In the context of the above scenario, this chapter focusses on the use of PGPR to increase agro-productivity and as one of the vital drivers of the agro-economy. In this review we focus on the modes of action of PGPR and their role in environmental protection and agricultural sustainability under increasing climatic variations.

Plants encounter various challenges that impact on growth and development. In the agricultural scenario, any limiting condition can transform into serious economic losses. Conventional methods employed to deal with biotic and abiotic stresses, including chemical methods, plant breeding, genetic engineering and other modern practices, present a variety of practical concerns. For example, transgenic plants can lead to selection pressure on the parasites thus providing a means to develop resistance. Hence a shift towards exploring the potentialities in plant growth-promoting microbes (PGPM) as a part of mainstream agricultural practices is imperative. In this review, we focus on PGPM (inclusive term for plant growth-promoting rhizobacteria and fungi), which, apart from their plant growth-promoting activities, also play a role in plant diseases control as well as in alleviating the impact of abiotic stresses. A deeper understanding of the mechanisms by which PGPM modify plant stress responses to boost their resistance and the nuances of the PGPM-host interactions would lead to increased acceptance of PGPM in agricultural applications.

Dillenia indica Linn. (Dilleniaceae) is generally known as elephant apple and locally known as outenga. The vernacular names are chalta, chulta, bhavya, karambel, ouu, and ramphal. This evergreen deciduous tree is markedly disseminated in the seasonal tropics of many Asian countries, in India from Himalaya to south India. The different parts of this plant have been prevalently investigated for the plethora of biological activities including anticancer, antidiabetic, antihyperlipidemic, antileukemic, antioxidant, antimutagenic, antimicrobial, antinociceptive, antidiarrheal, and hairweaving activities. Differently prepared extracts of this plant have been reported mainly to contain a wide range of flavonoids, triterpenoids (lupene-type), phytosteroids, phenolics, alcohols, and ketones and an anthraquinone. Several phytochemical investigations revealed substantial presence of various types of active constituents including β-sitosterol, stigmasterol, betulin, betulinic acid, kaempferol, myricetin, quercetin, dillenetin and rhamnetin. Among these the major chemical constituents are betulin and betulinic acid (lupene-type triterpenoids) that show a wide spectrum of pharmacological activities like anti-HIV, anticancer, antimalarial, anti-inflammatory, etc. The present chapter thus approaches to highlight on phytochemistry, traditional and therapeutic uses, and biological activities of Dillenia indica.

The Indian power sector has developed huge infrastructure for power generation, transmission and distribution of energy since the major utilization of fossil fuel has been an obstacle to achieve energy sustainability. Moreover, inadequate efficiency to treat the municipal and industrial wastewater is also generating serious environmental hazards. Thus concurrent management roadmap is required to tackle these challenges. In this context, algae have enormous efficiency to deal the challenges related to environment as well as energy sustainability. Algae have unique potential to grow under variety of environmental conditions due to flexible metabolic pathways. Wastewater generation and its adequate treatment are two of the major challenges to achieve the environmental sustainability that can be resolved through integration of algal cultivation in wastewater treatment systems. In this article, a holistic view on implication of algal microbiology for wastewater remediation and bioenergy production is provided. The procedures, associated challenges, and advancement in line of algal biofuel production explored by various authors are studied to project better ways for algal biofuel production process. A variety of pollutants as nutrients and their impact on lipid production in algal biomass are considered as the main advantages of this holistic approach. Advancements and challenges in algal harvesting and conversion processes for biodiesel production are also reviewed.

Constructed wetland microcosms (CWMs) are engineered wastewater treatment systems that are designed to treat wastewater from small communities, involving aquatic plants, a variety of substrate materials, soils and their associated microbial fauna. CWMs are considered as promising ecological technology that requires low or no energy input, low operational cost and provides more benefits and better alternative to conventional wastewater treatment systems. In CWMs dissolved oxygen (DO), pH and temperature are controlled to achieve the desirable treatment efficiency. Several other components such as plant, substrate, water depth, hydraulic loading rates (HLRs) and hydraulic retention time (HRT) are also critical to establishing viable CWMs for the better performance. The literature on CWMs suggests excellent nutrient removal performances which are achieved with low and stable effluent concentrations. Further, the choice of appropriate macrophyte species having high uptake of pollutants and high pollutant tolerance and choice of substrate materials are critical for treatment performance. CWMs can be differentiated based on existing native vegetation type (such as floating leaved macrophytes, free-floating macrophytes, emergent macrophytes and submerged macrophytes, in which emergent macrophytes are common) and, hydrology (surface flow constructed wetlands (SFCWs), subsurface flow constructed wetlands (SSFCWs) and hybrid systems). The focus of this paper is to review the state of the art in improving the overall efficiency of CWMs for wastewater treatment. The paper documents both the design and operation of CWMs which are critically dependent on environmental, operational and hydraulic factors. It further outlines key challenges and future prospects for their wider replication.

River water bodies serve as prominent water sources for various purposes ranging from drinking water, waste load allocation, irrigation, hydropower generation and ecosystem services. Human activities and natural processes require a balanced water supply and demand, while population growth, land use and climate change are the external forces which try to change the stream and river water quantity and quality. Water temperature is an inherent property of its quality and a controlling factor of health of freshwater environments. It is often considered as a driver of metabolic activity in water bodies, which influence the biological and chemical processes affecting the metabolic responses from organisms to ecosystems. The present work aims to explore sources of predictability of river water temperature (RWT) as a keen driver of hydrological and ecological processes at multiple scales. Increasing RWT in response to climate change and local-to-regional anthropogenic activities result in decreasing dissolved oxygen (DO) levels and anaerobic conditions in the aquatic system, thereby affecting marine life and the consequent availability of food, reproduction and migration. An assessment of integrated RWT and streamflow fluctuations is proposed to evidence biological activity, chemical speciation, oxygen solubility and self-purification capacity of a river system and fluctuations of flows responsive to hydro-climate pulses. The independent and integrated contributions of air temperatures and flow fluctuations to RWT in the Missouri River near Nebraska City, USA, represent the stream responses to global raising temperatures. To quantify the contributions of multiple variations of predictor variables in the air-water interfaces to RWT variability, we use a multiple regression. The performance of the model was tested along Missouri River near Nebraska City, USA, using historical series of daily river water temperature, air temperature and river discharges for the 1947–2014 period. A sensitivity analysis on river water temperature is performed, under air temperature increase of +2 °C, +4 °C and + 6 °C with a decrease of discharge of ±20%. Overall, the increase of RWT for the Missouri River is observed as about 2.76 °C under various air temperature and discharge changes when compared with the observed conditions at mean annual scale. The study results provide a comprehensive analysis of the impacts of river discharge and air temperature changes under climate change over RWT.

Though cellular architecture and functions show vast array of adaptive features to combat extreme temperature regime, enzymes are the key determinants of thermal adaption in both extremes of life, i.e., psychrophily or thermophily, as they drive the metabolism and cell cycle. Psychrophilic enzymes exhibit high specific activity at lower temperature range by disappearance of non-covalent stabilizing interactions (H bonding, hydrophobic interactions, salt bridges, etc.) and proline and arginine residues which cause improved flexibility (local/global) in conformation of enzymes. These enzymes have devised diverse ways to achieve the feat to live in extremity. Thermophilic enzymes work totally opposite to psychrophiles, i.e., by increasing proline number that causes proline isomerization which renders them to be more rigid and have higher arginine content which leads to increased salt bridge formation and extensive H bonding, etc. Oligomerization and heat shock proteins further give microbes stability against temperature.

Energy and environment are the opposite sides of the same coin. Increasing energy production depends on the fossil fuel availability and is the main cause of the environmental degradation by emission of greenhouse gases. To overcome the environmental degradation problem, the whole world is moving towards the renewable energy technologies. The sun is the main direct source of all forms of energy present on the earth. The solar energy can prove to be the sustainable future for maintaining energy demand. Solar energy is the utmost auspicious technology because it can be used for heating as well as electricity production. This technology is the most mature technology and can be used at large or small scale as cleanest source of energy. This chapter deals with the different solar energy technologies mainly working towards the environmental sustainability and cleaning.

Many organic, inorganic and natural dye sensitizers have been trailed in the past in an attempt to reduce the cost, improve the performance and make the dye-sensitized solar cell (DSSC) technology more environment-friendly. Ruthenium-based complexes are by far the most efficient dye sensitizers and have been commercially used in DSSC technology and achieved approximately 12–14% conversion efficiency. But the problems associated with ruthenium complexes are high cost and toxicity which drive the researchers to identify new metal-free and environment-friendly dye sensitizers such as organic and natural sensitizers. In this regard, natural dye sensitizers due to their low-cost extraction and environment-friendly nature are becoming a new area of research in the field of DSSC technology. These dye sensitizers are naturally occurring dye pigments, such as chlorophyll, betanins, carotenoids, anthocyanins and tannins extracted from flowers, leaves, stems and roots of plants using water, acetone and/or alcohols. At present, the efficiency of natural dye sensitizers is quite low compared to ruthenium-based dye due to selective light absorption. Recently, highest recorded efficiency of 2% has been reported using cocktail of natural dyes extracted from flowers. Attempts have been made to improve the performance of natural dye sensitizers by making cocktails and/or by using a variety of solvents for the extraction of dye molecules.