**1. Introduction**

Arsenic (As) is the one the most toxic element present in earth which poses a serious health hazard to animal and human health. Generally arsenic is present

in the earth crust in the form minerals, especially associated with iron pyrite and zinc ores. Arsenic contamination occurs through both by natural as well as anthropogenic processes [1]. Unlike other toxic heavy metals (Cadmium, mercury and chromium) arsenic contamination in environment predominately occurs through natural biogeochemical process [2] and some manmade activities play important role (triggering the process) in that process. Anthropogenic activities such as coal mining and burning smelting of As containing metal ores and other industrial activities are also responsible for distribution of arsenic in the environment [3]. Arsenic contamination of drinking water in South and Southeast Asia reported one of the most threatening problems that causes serious health hazard of millions of people of India and Bangladesh [4]. The source of As contamination in water in those countries were due to two different natural processes; oxidation of arsenopyrite minerals lies below ground water table due to water mining process and reduction of As containing iron hydroxides [5]. Arsenic exists in the nature in −3, 0, +3 and + 5 oxidation states and environmental forms include arsenious acids, arsenic acids, arsenites, arsenates, methylarsenic acid, dimethylarsinic acid, arsine, etc. Two inorganic forms are very common in natural waters: arsenite (AsO3 3−) and arsenate (AsO4 3−), referred to as arsenic (III) and arsenic (V). Pentavalent (+5) or arsenate species are AsO4 3−, HAsO4 2−, H2AsO4 − while trivalent (+3) arsenites include As(OH)3, As(OH)4 −, AsO2OH2− and AsO3 3−. The solubility of inorganic species depends on pH and redox potential of the environment and arsenite (As3+) is the most soluble form inorganic As. Pentavalent species or arsenate (As5+) predominate in oxygen rich aerobic environments, where as trivalent arsenites (As3+) dominant in moderately reducing anaerobic environments such as groundwater [4].

Arsenic concentration in drinking water reported more than 50 μg L−1 in many areas in the world [6], whereas maximum permissible limit set by World Health Organization (WHO) is 10 μg L−1. The use of arsenic contaminated ground water for irrigation purpose causes build up of As in soil and leads to entry of As in food crops, especially in rice and vegetables [7, 8]. This causes serious health hazard, in those As containing areas. In Southeast Asian countries like Bangladesh, Eastern parts of India (West Bengal and Bihar) and Vietnam, rice is consumed as major staple food and is very efficient in As translocation in grains [9]. Thus rice crop play a major pathway for As entry in human body living in those contaminated areas apart from drinking water. Thus remediation of arsenic contaminated water is important for environmental point of view. Various technologies are for remediation of arsenic contaminated water like ion exchange, electro dialysis, membrane filtration, adsorption and coagulation-flocculation generates lot of arsenic enriched waste. That waste material generally dumped or disposed in nearby surroundings, from where arsenic can also come back to soil and water by leaching thus making system susceptible to arsenic contamination. Along with above mentioned problem, huge cost is involved in this existing arsenic remediation technology. That necessitates finding out an alternate low cost technology which can take care of arsenic contaminated water.

Phytoremediation is an alternate and low cost technology that utilizes green plant to extract arsenic from water and store it vegetative cells. Phytoremediation process includes phytoextraction, phytostabilization, phytovolatilization, phytotransformation, and rhizofiltration [10]. Researchers find out that plants uptake arsenic by roots through phosphate uptake pathway and transfer it their above ground parts (shoot and leave). But how much amount of arsenic translocated from source (water) to sink (plant parts) depends on phytoremediation efficiency of the plant concern. However, more than 90% of total arsenic accumulated into the plant is stored in roots.

The plants utilized for phytoremediation have some criteria like (1) plant have higher specific growth rate under contaminated environment, (2) higher *Phytoremediation of Arsenic Contaminated Water Using Aquatic, Semi-Aquatic and Submerged... DOI: http://dx.doi.org/10.5772/intechopen.98961*

translocation capability of the toxic element concerned [11]. Metal translocation capability depends on factors like (1) bio concentration factor (BCF) and (2) translocation factor (TF). Plants having BCF >1 are ideal for Phytoremediation. Chinese brake fern (*Pteris vittata*) is the most promising plant for phytoremediation of arsenic from contaminated soil [12]. For instance, plants species like water hyacinth (*Eichhornia crassipes*), duck weed (*Lemma minor, Spirodela polyrhiza* and *Wolfia globosa*), water lettuce (*Pistia stratiotes*) and fern (*Azolla pinnata*) have been successfully utilized for arsenic removal from water purpose by many researchers [13–15]. Among the semi aquatic weeds. Apart from these free floating aquatic weed flora such as *Arundo donax*, *Vetivaria* sp., and *Alternanthera philoxeroides* had been successfully utilized for remediation of As contaminated water [16, 17]. In this chapter we are going to discuss about arsenic removal potential of various aquatic and semi aquatic weeds along with their future use for phytoremediation purpose.
