Bioremediation of Chromium from Water and Soil by Vascular Aquatic Plants

Abstract

The ability of aquatic plants to absorb, translocate and concentrate metals has led to the development of various plant-based treatment systems. The potential to accumulate chromium by Scirpus lacustris, Phragmites karka and Bacopa monnieri was assessed by subjecting them to different chromium concentrations under laboratory conditions. Plants showed the ability to accumulate substantial amounts of chromium during a short span of one week. When the plants were grown in tannery effluent and sludge containing 2.31 μg ml -1 and 214 mg kg -1 Cr, respectively, they caused significant reduction in chromium concentrations. While there was an increase in biomass, no visible phytotoxic symptoms were shown by treated plants. The plants can then be harvested easily and utilized for biogas production.Chromium is one ofthe toxic metals widely distributed in nature. Ofthe two forms found in the environment, trivalent and hexavalent, hexavalent chromium is the form considered to be the greatest threat because of its high solubility, its ability to penetrate cell membranes, and its strong oxidizing ability (1). The large-scale uses of chromium in metallurgical, pigment and dye, and in textile, and electroplating makes these industries potential sources of chromium pollution. The tanning industry is also a major contributor of chromium pollution of water resources. In India, according to a recent estimate, ca 2,000-3,200 tonnes of elemental chromium escape into the environment annually from the tanning industries alone (2). Chromium concentrations in effluents usually range between 2,000-5,000 pg ml" 1 compared to the recommended permissible limit of 2 pg ml 1 . The management of large amounts of effluent discharged by the tanneries has become a formidable task in developing countries. Contamination of water resources by these effluents is posing serious health hazards and is a threat to aquatic ecosystems. 274

Assessment of Present Heavy Metals in Industrial Affected Soil Area of Mandideep, Madhya Pradesh, India

“…(Chandra et al, 1997), estimated that in India alone about 2600 to 4200 tonnes of elemental Cr escape into the environment annually from the tanning industries, with a Cr concentration ranging between 2000 and 5000 mg L−1 in the effluent compared to the recommended permissible limit of 2 mg L−1. Typical concentrations in natural soils are 1-1000 mg /kg soil (Cappuyns et al, 2002). In the present study chromium was found with the concentration of 6.6mg/kg to 246.0 mg/kg in wet season and 6.9 mg/kg to 256.0 mg/kg in dry season.…”

Comparative Uptake and P Hytoextraction Study of Soil Induced Chromium by Accumulator and High Biomass Weed Species

“…These are Ipomoea carnea, Dhatura innoxia, Cassia tora and Lantana camara (all are local weeds). Another example of a plant that has shown much promise in the treatment of metal pollutant is Phragmytes karka, it has the ability to take up chromium from contaminated water [10,22]. Though studies on Phragmytes karka were hydroponic, soil studies on chromium accumulation are scarce.…”

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“…In recent years, it has been used as a decorative plant, but its medicinal use has not been well established. Removal of heavy metals and pollutants from aquatic systems by H. umbellata has been studied 12,15 . In addition, Hydrocotyle spp.…”