Hyperaccumulation of Copper by Two Species of Aquatic Plants Hamizah Mokhtar, Norhashimah Morad, Fera Fizani Ahmad Fizri Environmental Technology Division School of Industrial Technology Universiti Sains Malaysia, Penang, Malaysia E-mail: ami_872001@yahoo.com, nhashima@usm.my, fera@usm.my Abstract— Phytoremediation is a relatively new approach to treat wastewater contaminated by organic and inorganic substances including heavy metals. The effectiveness of two aquatic plants, Centella asiatica and Eichhornia crassipes, were evaluated for their capabilities in removing copper from copper solution. The aim of this study is to determine the potential of these aquatic plants to act as hyperaccumulators. The aquatic plants were put in 8 liters of solution containing of 1.5 mg/L, 2.5 mg/L and 5.5 mg/L of copper, for a period of 21 days. Analyses of heavy metals contents were conducted using an Atomic Adsorption Spectrometer. Results showed an increase of copper within the plants’ roots and shoots tissues and a decrease of copper concentration in the solution. The maximum removal of copper in the solutions containing Centella asiatica was 99.6 as compared to 97.3 % in solutions containing Eichhornia crassipes. Centella asiatica accumulated a maximum amount of copper of 1353.0 mg/kg while Eichhornia crassipes accumulated 1147.5 mg/kg of copper in their roots. The accumulation of copper of more than 1000 mg/L in plants tissues indicate that both aquatic plants can be considered as hyperaccumulators of copper. Roots tend to accumulate a higher amount of copper than shoots due to translocation process. Significant removal of copper were obtained at p<0.01 for containers containing both aquatic plants, indicating that Centella asiatica and Eichhornia crassipes can be utilized in the phytoremediation method to remove copper from wastewater. Keywords - hyperaccumulation; copper; Centella asiatica; Eichhornia crassipes; phytoremediation I. INTRODUCTION The rapid pace of industrialization and urbanization activities has become a major environmental concern due to dispersal of wastes generated on the ecosystem. Heavy metals are one of the most hazardous contaminants that may be present in the aquatic ecosystem. These heavy metals are highly toxic to the aquatic biodiversity, and drinking contaminated water containing heavy metal poses severe health hazards in humans. Contaminations of copper, nickel and zinc are normally due to releases from a variety of sources including electroplating, mining, urban sewage, smelters, tanneries, textile industry and chemical industries [1]. According to Ministry of Health of Malaysia, the limit for drinking water quality is 0.01 mg/L for copper. The industrial effluent discharge standard for Malaysian inland water is 0.2 mg/L for copper, according to Environmental Quality Act, 1974 with latest amendment in 2000. Even though the industries may employ treatment systems to treat their effluents, sudden changes in their manufacturing processes or breakdown of wastewater equipment may cause wastewater containing heavy metals that exceed the discharge limits to be inadvertently released into the environment. Various methods have been employed to clean- up the effluents. These methods include ion exchange, chemical precipitation, disinfection, adsorption by activated carbons, reverse osmosis and nanofiltration. Most of these methods are expensive, require high energy and are not able to completely remove the heavy metals [2]. Contrary to this conventional method, phytoremediation, i.e. the use of trees of plants to remediate contaminated soil or water, is a relatively new approach which is considered more cost- effective and environment-friendly. The major benefits of using aquatic plant-based treatment system are that it requires much lesser energy, it is a completely natural system and very easy to regenerate [3]. Several plants species, such as water lettuce (Pistia stratiotes) [4], water lilies (Nymphaea spontanea) [3], parrot feather (Myriophylhum aquaticum), creeping primrose (Ludwigina palustris), and watermint (Mentha aquatic) [5] have been studied to determine their potential in accumulating heavy metals. Among the various plants species group, aquatic macrophytes attain greatest interest in the field of phytoremediation. Aquatic macrophytes have great potential to accumulate heavy metals inside their plants bodies. These plants can accumulate heavy metals up to 100,000 times greater than the amount in the associated water. Therefore, these macrophytes have been used for heavy metal removal from a variety of sources [4]. Aquatic macrophytes such as water hyacinth, is one of the most commonly used plants in constructed wetlands because of its fast growth rate and large uptake of nutrients and contaminants [1]. Eichhornia crassipes and Centella asiatica have also been shown to be effective in removing trace elements from water and accumulate them in their bodies [6]. In this study, two aquatic plants, Eichhornia crassipes and Centella asiatica, were used to determine their potential in removing Cu of various concentrations from copper solutions. Eichhornia crassipes and Centella asiatica are two of the most abundant aquatic plants in Malaysia and have been found to thrive in canals, rivers and man-made lakes. The effectiveness of the plants in removing copper from the solution as well as the potential of the plants to accumulate 115 2011 International Conference on Environment Science and Engineering IPCBEE vol.8 (2011) © (2011) IACSIT Press, Singapore