Technological Interventions in Management of Hg Contaminated Water

Rising cases of environmental mercury hazards has led to a need for cost-effective mercury treatment techniques. Extensive use of mercury from ancient times has resulted in water contamination that may require remediation. Mercury contamination is tedious to treat and may pose a risk to human health and the environment. To deal with this threat of mercury contamination, industrial wastes and wastewaters containing mercury requires treatment for its removal and immobilization. This chapter provides a synopsis of the availability, performance, and technologies for management of mercury in water. It covers the innovative methods to treat the mercury contamination like biosorption. In this chapter, the technological aspects available for the mercury treatment technologies are reviewed. It describes the theory, design, and operation of the technologies; provides information on commercial availability and use; and includes data on performance, where available.

Effective Removal of Heavy Metals From Aqueous Solution by Nano-Composites

Heavy metal contamination in industrial effluents presents a serious threat to the environment and human health because of their toxicity, non-biodegradability, carcinogenicity, and bioaccumulation in living organisms. Recently, the preparation and application of iron oxides, especially magnetite nanoparticles, for metals removal have been investigated due to their nano size, magnetic separation, and the ease of synthesis, coating, and modification. However, magnetic nanoparticles lose some magnetization due to air oxidation. Magnetite nanoparticles coating with inorganic shell, like silica and carbon, have been reported and were capable of improving chemical stability. The effects of pH, contact time, and initial concentrations on the removal of heavy metals should be studied using nano-composites in water. In this chapter, the authors present a technical review on different nano-composites used for bioremediation and their limitations.

Nano-Bioremediation

The functional aspect of nanotechnology (NBT) is driven either to accelerate the performance of materials and/or to reduce the quantity of materials that are used for the purpose. Most significantly, its potential attribute to the environment includes the treatment and remediation, sensing and detection, and pollution prevention. In general nano-bio remediation (NBR) involves the use of nano-materials either in in-situ (in place), or ex-situ (off-place) treatment of contaminated materials. To accomplish this, the elemental or zero-valent metals and like materials in nano-form (1-100 nm) have been applied as an instinctive need to embrace sustainable environment. The use of nanomaterials initially reduces the biodegradable contaminants and then it promotes to achieve the standard levels. Thus, the role of nano-materials could be an efficient, effective approach to remediate the environmental contaminant sustainably. However, further research is required to record the detailed fate of the nano-materials that are used in environment remediation.

Role of Plant Growth Promoting Bacteria (PGPB) for Bioremediation of Heavy Metals

The heavy metal pollution problem is all over the world. Plant growth promoting bacteria (PGPB) has transformed heavy metals present in the soil, which removes and minimizes their toxic effects. This chapter highlights the role of PGPB for remediation of heavy metals, their mechanism of action, and their applications approach of hyperaccumulation. Further, it also highlights the role of uptake and detoxification of metals by cellular mechanisms which facilitate the bioremediation of heavy metals from contaminated areas. Bacteria may also enhance nutrient uptake, increasing plant growth and defenses while diminish heavy metals intake and their toxic effects. Therefore, this chapter focuses on the mechanisms by which microorganisms can mobilize or immobilize metals in soils and the bioremediation strategies are addressed for the improvement of phytoextraction as an innovative process for enhancement of heavy metals removal from soil.

Biosorption of Uranium Heavy Metals

Uranium is a seriously threatening heavy metal because of its high toxicity and radioactivity. Uranium contaminates surface and groundwater. Metal removed from aqueous solutions often leads to effective metal concentration. Apart from the slow natural process of metal mineralization, removal of heavy metals is attained when the metal becomes concentrated at a point that it is either returned to the process or resold. Physical adsorption takes place due to van-der Waals' forces. Conventional methods used for uranium removal are expensive and produce huge amount of sludge (consists of toxic substances) which blockade the membrane. In this chapter, uranium removal by biosorption method is discussed. Uranium removal is attained by the use of either living microorganisms (bacteria, algae, and fungi) or their dead biomasses.

Biomining Microorganisms' Molecular Aspects and Applications in Biotechnology and Bioremediation

The effective dissolution of metals is widely known with the help of microorganisms called bioleaching or biomining used for the extraction of metals from their ores. Usually the microorganisms involved in biomining are chemolithoautotrophic and extremophilic in nature, since they are living in highly acidic environments (pH 1-3.0) containing heavy concentrations of metals. The commonly found genera of archea are Sulfolobus, Acidianus, Metallosphaera, and Sulfurisphaera. Throughput microbial genomics and proteomics analysis provides novel insights of metabolism mechanisms of bioleaching microbes. These microbes are having significant impact on the bioremediation of acid mine drainage (AMD) resulted from many industrial operations. Using these microbes, various metals including Ni, Cd, Cu, Fe, As, Pb, Hg, Cr, Mn, Zn, etc. are removed from the environment. Biomining microorganisms are having significant applications in the biotechnological processes including extraction of gold from ores, extraction of nickel from low-grade sulfide ores, extraction of copper from chalcopyrite, etc.

Nanoparticles for Bioremediation of Heavy Metal Polluted Water

The process of bioremediation can be intrinsic or natural attenuation, where the process of remediation happens on its own, or it can be extrinsic or bio-stimulated when it is incited with help of some growth productive conditions like addition of fertilizers or nanoparticles, the smallest active particles on the earth. Nanoparticles are charged entities with low activation energy and exhibiting quantum effects making the chemical reaction between the nanoparticle and surrounding feasible in lesser time, and they also exhibit surface plasmon resonance that helps in identification of toxic material in surrounding. Apart from these properties, their different shapes and sizes help in designing the environmental cleanup process as per the suitable conditions and requirements. Polluted water treatment is being done with the help of nanoparticles due to their property of being highly profitable as adsorbents and for filtration purposes.

Interaction of Heavy Metal Ions With Nanomaterials

Increasing water pollution due to heavy metals is a major global concern, and favorable remediation techniques are required. Heavy metal contamination affects both flora and fauna as it enters the food web. The development of nanotechnology and novel nanomaterials production has attracted researchers worldwide. Both carbon- and metal-based nanomaterials proved great adsorbents for heavy metal remediation because of their unique properties such as thermal and chemical stability and high surface. Novel green route for nanomaterials synthesis make the nanomaterials production an environmentally friendly, low cost, and user-friendly approach. This chapter reviews the heavy metal pollution causes and utilization of different nanomaterials for the remediation process.

Application of Plant Tissue Culture in Management of Hg Contaminated Water

In the chapter, the authors describe how a plant can be selected as a natural indicator of heavy metal (mercury) contamination, how one can select a plant species to monitor a particular type of heavy metal and use those plants to remove the contaminants from the area under consideration. The chapter also contains a brief idea of environmental contamination by heavy metals and how the situation can be managed by the techniques of modern plant biotechnology. The authors add some reports and data of their in-vitro studies of mercury toxicity on Ananas sp., generally known as pineapple, for better understanding of the text.

Low Cost Absorbents, Techniques, and Heavy Metal Removal Efficiency

Heavy metal contamination in water is a serious concern to the environment and human health. High concentrations of heavy metals in the environment can be toxic to a variety of living species. Natural bio-absorbents are abundant and inexpensive and considered a waste if not managed properly. The role of bio-absorbents has been widely studied and has been utilized for the removal of heavy metals. The objective of the chapter is to search the database for different absorbents and their efficiency for the removal of heavy metals. Key words related to the study have been used to select different papers published by the researchers all over the world. A rigorous three-tier process has been utilized by the authors to select the papers from the database for the current study. This chapter has identified a few research gaps in the field of heavy metal removal by using different low cast absorbents that need to be taken into account in future research.