Bioremediation Approaches for Recalcitrant Pollutants

The different chemical pollutants discharged by the industries to the environment can upset the delicate balance of the ecosystem. Bioremediation, the use of microorganisms and plants to remediate polluted environments, is a promising and growing area of environmental biotechnology. Bioremediation options encompass diverse types of biotechnological mechanisms that may lead to a target pollutant's mineralization, partial transformation, humification, or altered redox state. The use of extra cellular and/or cell-free enzymes has been also proposed as an innovative remediation technique. Perspectives and limitations to evolve and use this technology are critically discussed in this chapter with respect to the complexity of mixtures of xenobiotics often found in practice. Whereas the potential of bioremediation is substantial, its application has important limitations that are apparent from many examples and the authors feel that these limitations can be overcome only when adequate attention is directed to fundamental microbiological, chemical and engineering issues.

Novel Bioremediation Methods in Waste Management

Bioremediation technologies are one of the novel methods in the field of waste and environment management and are presently gaining immense credibility for being eco-compatible. Bioremediation using microbes has been well accepted as an environment friendly and economical treatment method for disposal of hazardous petroleum hydrocarbon contaminated waste (oily waste). Besides this, earthworms can be used to extract toxic heavy metals, including cadmium and lead, from solid waste from domestic refuse collection and waste from vegetable and flower markets. Other novel methods used recently for treatment of wastes are plasma incineration or plasma assisted gasification and pyrolysis technology. The technologies applied for conditioning include ultrasonic degradation, chemical degradation, enzyme addition, electro-coagulation and biological cell destruction. Genetic engineering is another method for improving bioremediation of heavy metals and organic pollutants. Transgenic plants and associated bacteria constitute a new generation of genetically modified organisms for bioremediation.

Advances in Bioremediation for Removal of Toxic Dye from Different Streams of Wastewater

Azo dyes are used in abundance in several industries like textile, printing, paper, plastic, cosmetics, paints, etc. Extensive discharge of such dyes in adjacent water bodies has raised much environmental concern. Azo dyes are toxic to living organisms and their genotoxic and carcinogenic potentials are intensified on being released as mixtures. In the recent years, various microorganisms have been isolated and reported to possess tremendous potential for efficient dye degradation. However, the process of bioremediation is highly controlled by experimental factors like effluent pH, temperature and concentration of dyes in solution. Therefore, appropriate optimization of these factors is to be determined in order to ensure maximum efficiency of this process. This review highlights application of immobilization techniques of bacterial cells for achievement of successful biodegradation. In this study, the existing problems of dye pollution and possible improvisations for obtaining enhanced bioremediation of dyes have also been discussed.

Heavy Metal Pollution

The chapter covers various issues related to heavy metals. Here we attempt to document the possible definitions for heavy metals. Heavy metals, the elements having density higher than 3.5 g/cm2 are being added at high rate to our close vicinity. These metals lead to serious problems related to ecology and mankind. Toxic effects of heavy metals are dependent on the concentration of metals, reactivity of metal species and duration of exposure. There is a need to address the toxicological and remedial aspects of heavy metals.

Phyto-Remediation: Using Plants to Clean Up Soils

In this chapter authors have discussed the role of plants to develop contaminant free environment. This concept is also known as Phytoremediation. Phytoremediation is a word formed from the Greek prefix “phyto” meaning plant, and the Latin suffix “remedium” meaning to clean or restore. This technology has been receiving attention lately as an innovative, cost-effective alternative to the more established treatment methods used at hazardous waste sites. Phytoremediation can be classified into different applications, such as phytofiltration or rhizofiltration, phytostabilization, phytovolatilization, phytodegradation and phyto-extraction etc. The chapter will deal with phytoremediation, its advantages, limitations and in detail techniques of classification and application.

Genetically Engineered Microorganisms for Bioremediation Processes

In the past few decades, environmental pollution is a major issue which affects biodiversity public health and eco systems present in worldwide, nowadays, microbial potential are connected to effect the clean-up of environmental pollutants. Conventional methods are focus on the separation, rather than the destruction of contaminants, the use of genetically engineered microorganisms for bioremediation would be an alternative, environmentally friendly, more effectiveness and economical clean-up technique for the remediation of pollutants in present in contaminated sites. A combined strategies relationship between genetic engineered microbes and bioremediation can enhance the effectiveness of contaminants sites. Here, we have elaborated recent work on the investigation and improvement of these microbes using genetic tools and given an outlook of what may be possible in the near future.

Biosorption of Dye Molecules

Water contamination due to dyes has drawn increased attention. Dyes in water bodies are greatly perceptible and pose tremendous threat to ecosystem. Thus removal of such dye molecules is a matter of concern. In the past various physical and chemical techniques have been employed for the removal of colour from wastewater. However most of these methods have certain drawbacks. Biological treatment is often efficient and economical. Many microorganisms are able to accumulate and degrade different pollutants. Yet even the biological methods have some shortcomings such as toxicity of biodegradation products and more.

Biodegradation of Phenol

Aromatic compounds are widely distributed in nature. Free phenols are frequently liberated as metabolic intermediates during the degradation of plant materials. In recent years the natural supply of phenolic substances has been greatly increased due to the release of industrial byproducts into the environment. Phenolic compounds are hazardous pollutants that are toxic at relatively low concentration. Effluents from petrochemical, textile and coal industries contain phenolic compounds in very high concentration; therefore there is a necessity to remove phenolic compounds from the environment. Microorganisms capable of degrading phenol are common and include both aerobes and anaerobes. The use of microbial catalysts in the biodegradation of organic compounds has advanced significantly during the past three decades. The efficiency of biodegradation of organic compounds is influenced by the type of the organic pollutant, the nature of the organism, the enzyme involved, the mechanism of degradation and the nature of the influencing factors.

Application of Genomics and Proteomics in Bioremediation

Bioremediation mediated by microorganisms is proving to be cost effective, ecofriendly and sustainable technology. Genome enable experimental and modeling techniques are of a great help in evaluating physiology and enhancing performance of life forms to be used for bioremediation purpose. Similarly, the application of proteomics in bioremediation research provides a global view of the protein composition of microbial cell and offers promising approach to understand the molecular mechanism of removal of toxic material from the environment. Combination of proteomics and genomics in bioremediation is an insight into global metabolic and regulatory network that can enhance the understanding of gene functions. Present chapter give a bird's eye view of genomics and proteomics and their potential utilization in bioremediation and for the clearer understanding of the cellular responses to environmental stimuli. An understanding of the growth conditions governing the expression of proteome in a specific environment is essential for developing rational strategies for successful bioremediation.

Heavy Metal Pollution and its Management

Environmental degradation has become a major societal issue thanks to uncontrolled anthropogenic activity, besides natural factors. Entry of toxic heavy metals and minerals in human system mainly through contaminated water, food and air, leads to overt and insidious health problems. Heavy metal pollution, a global concern today, can be managed by using bioremediation, an eco-friendly alternative. Bioremediation is one of the most promising technological approaches to the problem of hazardous waste. It is a technology for removing pollution from environment, restoring contaminated site and preventing future pollution. Bioremediation can be performed in situ or ex situ. Microorganisms directly degrade contaminants rather than merely transferring them from one medium to another, employ metabolic degradation pathways and can be used in situ to minimize disturbance of the cleanup site. Hence, microorganisms can be effective, economical and non-disruptive tools for eliminating hazardous chemicals. Its advantage generally outweigh the disadvantage, therefore may be used as management tool.