PHYTOREMEDIATION DEFINITION Phytoremediation is an emerging technology which

PHYTOREMEDIATION

DEFINITION �Phytoremediation is an emerging technology which uses plants and their associated rhizospheric microorganisms to remove, degrade or contain chemical contaminants located in the soil, sediments, groundwater, surface water, even the atmosphere. OR �The process by which various pollutants are removed from soil, water, or air by plants. �Phytoremediation comes from 2 words: I. Phyto(Greek)= plant II. Remedium(Latin) = restoring balance or

PRINCIPLE OF PHYTOREMEDIATION �Use plants to "vacuum" heavy metals from the soil through their roots �Certain species have the ability to extract elements from the soil and concentrate them in the stems, shoots, and leaves �The unique plants must be able to tolerate and survive high levels of heavy metals in soils-like zinc, cadmium, and nickel. �These plants possess genes that regulate the amount of metals taken up from the soil by roots and deposited at other locations within the plant. �Some contaminants also changed into safer gases as plant transpires.

FORMS OF PHYTOREMEDIATION

1. PHYTOEXTRACTION �Phytoextraction is a form of phytoremediation in which plants remove dangerous elements or compounds from soil or water, most usually heavy metals, metals that have a high density and may be toxic to organisms even at relatively low concentrations. �The heavy metals that plants extract are toxic to the plants as well, and the plants used for phytoextraction are known as hyperaccumulators that sequester

2. RHIZOFILTRATION �Rhizofiltration is a form of phytoremediation that involves filtering water through a mass of roots to remove toxic substances or excess nutrients. �This process is very similar to phytoextraction in that it removes contaminants by trapping them into harvestable plant biomass. �First, plants are put in contact with the contamination. They absorb contaminants through their root systems and store them in root biomass and/or transport them up into the stems and/or leaves. The plants continue to absorb contaminants until they are harvested. The plants are then replaced to continue the growth/harvest cycle until satisfactory levels of contaminant are achieved.

�Both processes are also aimed more toward concentrating and precipitating heavy metals than organic contaminants. �The major difference between rhizofiltration and phytoextraction is that rhizofiltration is used for treatment in aquatic environments, while phytoextraction deals with soil remediation.

3. PHYTOSTABILIZATION �Phytostabilization focuses on long-term stabilization and containment of the pollutant. �e. g. , the plant's presence can reduce wind erosion; or the plant's roots can prevent water erosion, immobilize the pollutants by adsorption or accumulation, and provide a zone around the roots where the pollutant can precipitate and stabilize. �Unlike phytoextraction, phytostabilization focuses mainly on sequestering pollutants in soil near the roots but not in plant tissues. �Pollutants become less bioavailable and livestock, wildlife, and human exposure is reduced.

4. PHYTODEGRADATION �It is also known as phytotransformation. �The breakdown of the contaminants taken up by the plants through metabolic processes within the plants. OR �The breakdown of the contaminants surrounding the plants through the effect of compounds (enzymes) produced by the plants. �Complex organic pollutants are degraded into simpler molecules and are incorporated into the plant tissues and accelerate growth. �Plants contain enzymes that catalyze and accelerate the chemical reactions.

PHYTOVOLATILIZATIO N �Phytovolatilization is a process, in which plants take up contaminants from soil and release them as volatile form into the atmosphere through transpiration. �The process occurs as growing plants absorb water and organic contaminants. As water travels from the roots to the leaves along the vascular system of the plant, it is changed and modified along the way. Then, some of the contaminants move through the plants to the leaves and evaporate or volatilize into the atmosphere. �Phytovolatilization has been primarily used to