Bioremediation and Phytoremediation Technologies in Sustainable Soil Management

Volume 1: Fundamental Aspects and Contaminated Sites

Junaid Ahmad Malik, Megh R. Goyal, Khursheed Ahmad Wani, Junaid Ahmad Malik, Megh R. Goyal, Khursheed Ahmad Wani

• Éditeur: Apple Academic Press
• Année: 2022
• ISBN:
  9781000570236
• Édition: 1
• Sujet: Tecnología e ingeniería
• Sous-sujet: Agronomía

This 4-volume set focuses on the use of microbial bioremediation and phytoremediation to clean up pollutants in soil, such as pesticides, petroleum hydrocarbons, metals, and chlorinated solvents, which reduce the soil's fertility and renders it unfit for plant growth.

Volume 1: Fundamental Aspects and Contaminated Sites begins with an overview of phytoremediation and the role of environmental factors. It goes on to introduce soil assessment techniques and offers methods of remediation designed to combat soil and agricultural degradation. It discusses soils contaminated by heavy metals; microbial and phytoremediation-based removal of polycyclic aromatic hydrocarbons (PAHs) from coal, crude oil, and gasoline; microbial bioremediation and amelioration of pesticide-contaminated soils; phytoremediation techniques for biomedical waste contaminated sites; as well as biomediation processes for human waste sites. Biopesticides are also explained as an alternative to conventional pesticides.

Other volumes in the 4-volume set:
• Volume 2: Microbial Approaches and Recent Trends
• Volume 3: Inventive Techniques, Research Methods, and Case Studies
• Volume 4: Degradation of Pesticides and Polychlorinated Biphenyls

Together, these four volumes provide in-depth coverage of the mechanisms, advantages, and disadvantages of the bioremediation and phytoremediation technologies for safe and sustainable soil management.

PART I Fundamental Aspects

CHAPTER 1 PHYTOREMEDIATION AND PHYTOTECHNOLOGIES: AN OVERVIEW

IRFAN-UR-RAUF TAK and SOFI MOHAMMAD ZUBER

ABSTRACT

Heavy metal (HM) contamination is considered a serious ecological pollution as it can impact the development of industries in various countries. This pollution can also cause several diseases in humans. A number of techniques have been employed to remove HMs from the environment and soil, such as phytoremediation, which aims at removing the pollutants from adulterated soils and water by means of plants. In contrast to this, “phytotechnologies make use of vegetation to contain and remove organic and inorganic contaminants that are present in the soil, surface waters and in the groundwater.” This chapter provides a brief perspective on recent advancements in the research and practical applications of phytoremediation and phytotechnologies.

1.1 INTRODUCTION

Land, soil, and water have been subjected to a number of exploitations because of various anthropogenic activities, which have resulted in their degradation. Efforts have been made to reduce the pollution sources. Phytoremediation has been observed to be an effective technique because it has lower side effects than the conventional methods. In this context, the soil contamination has been a significant ecological problem due to its impacts on human health.

Contaminated sites are present throughout the world, which is in need of immediate cleanup to safeguard our wellbeing. In comparison, phytotechnologies can help to protect the environment by using plants to extract and immobilize pollutants that are present in soil, surface water, and groundwater. Phytotechnologies have found its applications in solid wastes related to mining. These can also help in stabilizing the tailings and to act as hydraulic control for drainage purposes, thus minimizing the contaminant exposure to humans. Phytotechnologies have also found its applications in the elimination of metals from the adulterated media, and this process requires the selection of plant species in a careful manner. These systems, once fully established are able to maintain with minimum efforts.

The present chapter focuses on various aspects of phytoremediation and phytotechnologies. Different methods and techniques and their general remediation capacities have been discussed besides highlighting on their advantages and limitations.

1.2 ROLE OF PHYTOREMEDIATION AND PHYTOTECHNOLOGIES

Contamination of land with heavy metals (HMs) is one of the most hazardous issues as it has been known to cause a decrease in the function of the soil. It has been found to affect the health of the humans and ecosystems and economic welfare [69]. Human intervention is needed in such cases to make use of existing technologies for the purpose of removing the pollutants. Physiochemical techniques can overcome this pollution. Providing chemical substances are one of the ways to remove the contaminants from the land and besides this.

Another way is to replace the contaminated land with other lands [70]. This later method encompasses the elimination of adulterated soil with clean soil. This technique has however many limitations, which mainly include the removal of the original soil [47]. To overcome these limitations, an eco-friendly favorable phytoremediation technique is employed at an affordable cost. This technique makes use of specific plants to remove the soil pollutants. Besides this, it also helps in reducing the toxic effects of contaminants from the surrounding environment [25, 71]. This technique has great potential to implement on different types of pollutants and also helps in recovering soil functions [10, 37]. This technique also includes soil fertility to allow the growth of the plants, which have added their economic values [63]. It has, however been seen that this technology could not be fully implemented by farmers, who lack knowledge, thus causing failure in the implementation of these technologies in HM contaminated lands. Therefore, farmer’s knowledge and their training are essential for the success of these techniques.

In contrast to this, phytotechnologies are plant-based methods for the detection and removal of the contaminants present in the soil and in the groundwater [23]. The strategies are aimed at preventing the diseases that are caused by environmental exposures [9]. While the society is mainly concerned with the fact that sanitation helps in preventing the exposure to various types of communicable diseases, we remain less concerned about the fact that the environment plays a significant role in the prevention of the diseases. The success of various remediation techniques is determined by various types of clean-up goals, which are necessary.

Remediation tools and phytotechnologies have been known to have both advantages as well as disadvantages. The most common feature of using phytotechnologies when compared to other methods is their low cost and high acceptance for clean-up purposes [15, 23]. When evaluating the phytotechnologies in terms of capital costs, it is mainly involved with cultivating the plants in situ for proper conservation of energy and water. As a clean-up tool based on phytotechnologies, there is proper reduction of secondary pollutants that are associated with the remediation. The positive impacts of phytotechnologies involve protecting the surrounding environment besides providing various kinds of ecosystem services [21]. While assessing the phytotechnologies in terms of esthetic values, it has a great community appeal and acceptance [3] due to covering the contaminated site with various types of vegetations for reducing stress in urban environment [19]. It is because of these facts that phytotechnologies have a widespread public acceptance because it primarily helps in minimizing the exposure to various contaminants, besides helping in improving the quality of food, air, and water resources.

1.3 POTENTIAL OF PHYTOREMEDIATION

Phytoremediation is an in-situ and solar-powered methodology that helps in removing and transforming the pollutants besides metabolizing them [18, 44]. The plants that are used can subsequently be harvested and disposed-off very safely. It has been observed that plants can take up the pollutants through their root system and this property helps in detoxification and cleaning-up the pollutants. It is this property of plants for removing or elimination of the wastes, most importantly metals and phenolic compounds. It has also been observed that the plant-microbe interaction has an important role to play in maintaining the physiology and health of the plant. Plants have been for very long known to provide shelter to diverse kinds of microbes, which then ultimately help in degrading the toxic pollutants. Plants make use of a number of mechanisms to uptake and then degrade the inorganic and organic pollutants [48]. Some of the mechanisms used by the plants for the decontamination of polluted soils are discussed in this section.

1.3.1 PHYTOEXTRACTION

It is a cost-effective method through which plants can take up the soil contaminants, especially the metal contaminants through roots and then can transport them to shoots and leaves [33, 41]. Number of plants especially hyperaccumulator plants can accumulate a number of metals in their shoots without showing any visible symptoms [17]. These plants have been found to employ a number of metabolic processes for the purpose of up-taking and mobilizing the metal ions that are present in the soil and then convert them into less toxic forms [28]. After the metals have been accumulated, the resulting plant biomass is finally harvested and is then composted for the purpose of recycling the metals. A plant will be considered as an ideal hyperaccumulator, if it has a high biomass and is rapidly growing besides having high capability to accumulate the metals in its shoots. Both BCF (bioconcentration factor) and TF (translocation factor) have been seen to be very important parameters in the studies of HM uptake [67]. Such plants are considered to be a potential candidate for the phytoextraction of metals from the contaminated sites [20, 22, 33]. Also, plants with BCF value >1 and TF value <1 can have significant potential for phytostabilization [16].

1.3.2 PHYTOSTABILIZATION

It makes use of different types of plant species for immobilizing the HMs that are present in the soil. This is possible through different processes, which mainly include accumulation and precipitation. It helps in reducing the movement of metals and thereby prevents them from leaching into the groundwater and thereby preventing the metal ions from entering into ...