Combined application of biochar, compost, and bacterial consortia with Italian ryegrass enhanced phytoremediation of petroleum hydrocarbon contaminated soil

The burning issue of today,s environment problem is the release of toxic contaminants from various man made sources resulting in contamination of natural resources of earth and leading to scarcity of clean water and loss of soil fertility. To overcome these drawbacks,the concept of using plant to clean up contaminated environment is not new. about 300 years ago, plants were proposed for use in the treatment of waste water.land and water pollution by heavy metals is a world wide issue. therefore has been an increasing concern with regard to accumulation of heavy metals in environment as they pose big threat to both human health and natural environment. in central and eastern european countries about 1.7 million sites were contaminated with heavy metals and need reclamation. in developing countries particularly india, china, pakistan, bangladesh, soil and water pollution is also severe where small industrial units are pouring their untreated effluents over near agricultural fields.the use of plants species for cleaning polluted soils and water named as phytoremediation has gained increasing attention since last decade, as an emerging cheaper technology. This article reviewed the status of phytoremediation in global prospects.

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Status of Phytoremediation in World Scenario

Mining practices and the absence of proper mine land reclamation has led to heavy metal contaminated sites with serious impact on the ecosystems and risk for human health. The origin of the contamination is often associated to mine tailing deposits because they are a source of the acid mine drainage (AMD). These areas are devoid of vegetation due to the harsh soil conditions that prevent the rooting of plant species. The remediation of these areas followed by revegetation is necessary to suppress the generation of the AMD and its negative effects on the ecosystems. Conventional remediation technologies for heavy metal contaminated sites are usually not applicable because of the high cost associated with chemicals and energy requirements, as well as the long treatment time to remediate large areas. In this study, the use of phytocapping for the remediation of mine tailing deposits and abandoned mine areas is reviewed. Phytocapping is cost effective, environmentally friendly and has multifunctional role against various problems of mine tailings: it provides erosion control, landscape rehabilitation, enhances the soil properties for further colonization of other more demanding vegetal species, reduces the leachability of metals downwards the groundwater, and favors the immobilization of metals forming less bioavailable species. The most critical step in phytocapping is the developing of the first vegetative cover because of the biotoxicity of the mine soil and mine tailings. Several amendment materials can be used to ameliorate soil conditions creating a favorable environment for the rooting of plants, as well as serving as a source of nutrients. Local plant species with fast growing are preferable because their adaptation to the soil and climate conditions favors their self-propagation.

Mine tailing disposal sites: contamination problems, remedial options and phytocaps for sustainable remediation

Phytoextraction, as the most commonly used technique in phytoremediation, involves the utilization of plant-hyperaccumulators for the absorption pollutants (primarily heavy metals) from the environment, their transport, and concentration in the biomass of harvestable organs. This in situ, cost-effective technology could improve the quality of moderately contaminated lands and waters within realistic time scales. For a successful implementation of phytoextraction, the main prerequisite is to identify native plants which are able to extract (absorb), degrade, or sequester hazardous contaminants from growing media and develop strategies for making hybrids and genetically modified plants which are good candidates for phytoextraction. Because of their rapid growth rate and high biomass yield, their adaptability to different ecological conditions and genetic variability is outstanding. Willows and poplars from the Salicaceae family are valuable resources for the use of phytoremediation. Also, species like the eucalypt, black locust, birch, and paulownia are defined by numerous researchers as good candidates for phytoextraction due to their high metal bioconcentration ability and high yield. There have been numerous studies confirming that species with a role in phytoextraction developed a complex network of homeostatic metabolic mechanisms in order to control metal uptake, accumulation, (re)distribution, and detoxification.

Phytoextraction of Heavy Metals by Fast-Growing Trees: A Review

Bioremediation is considered as one of the safer, cleaner, cost effective and environmental friendly technology for decontaminating sites which are contaminated with wide range of pollutants. Various industrial and anthropogenic activities resulted in increased contaminated sites due to unawareness regarding production, use and disposal of hazardous substances. The process of bioremediation uses various agents such as bacteria, yeast, fungi, algae and higher plants as major tools in treating oil spills and heavy metals present in the environment. A continuous search for the new biological forms is required to regulate increasing pollution and environmental problems faced by man residing in an area. As microorganism shows wide range of mechanisms, there are still few mechanisms which are not known, therefore bioremediation is still considered as a developing technology. Thus, there is an urgent need to for us to review and modify the available options for environmental clean up. The objective of this paper is to conduct a comprehensive review on various sources of bioremediation agents and their limitations in treating pollutants present in the environment.

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Bioremediation: A Sustainable Tool for Environmental Management – A Review.

The increasingly anthropogenic release of toxic contaminants has led to the contamination of organic chemicals, such as phthalic esters (PAEs), Polycyclic Aromatic Hydrocarbons (PAHs), Polybrominated Diphenyl Ethers (PBDEs), Polychlorobiphenyls (PCBs), Petroleum Hydrocarbons (PHC), pesticides, etc [1]. Remediation of organicpolluted soils is becoming an increasing challenge worldwide [2]. Phytoremediation is an emerging technology that utilizes plants to clean up organic pollutants and toxic metals in water, sediments, or soils [3]. Phytoremediation has been accepted and utilized widely because it is a cost-effective and environmental friendly green technology with permanently removing the pollutants [4]. A large number of plant species have been found to be promising candidates for the phytoremediation of organic pollutants [5]. In general there are two approaches for the phytoremediation of organic-polluted soils based on the difference in remediative mechanism. First, organic pollutants can be taken up directly by plants, resulting in the sequestration or degradation of pollutants inside of plants [5], which is called phytoextraction. Second, organic pollutants can be degraded by plant-secreted enzymes or plant-modified microbial community in rhizosphere [5,6], which is called plant-assisted rhizoremediation.

Phytoremediation of Organic Polluted Soil

The remediation of metal-/metalloid-contaminated soils has been becoming a challenge worldwide As compared to traditionally physical–chemical approaches, phytoremediation is considered to be a “green approach” to clean up metal-/metalloid-contaminated environments by using plants to decrease the concentration of mobile metals/metalloids in sites According to the uptake and metabolism of heavy metals/metalloids in hyperaccumulating plants, phytoremediative techniques contain phytoextraction, phytostabilization, and phytovolatilization The wild hyperaccumulating plant species with a reasonable adaptability are limited However, the rapid development of genetic modification of plants is able to improve the efficiency of phytoremediation and thus to extend the application of phytoremediation in different metal-/metalloid-contaminated environments The site assessment and regulatory requirements are indispensable to optimize the application of phytoremediation Hazard assessment, risk management, and feasibility analysis should be carefully performed before applying and implementing phytoremediation Phytoremediation requirements must be considered on a site-by-site basis, such as the monitoring of the processes of phytoremediation on remediation sites and the safe handling of by-products after phytoremediation

Jian Chen

Papers

Phytoremediation of Organic Polluted Soil

Phytoremediation to Remove Metals/Metalloids from Soils