Short Communication 32 Advanced Biotech March 2009 | | Introduction Removal of colour from dye-bearing wastewaters is one of the major environmental problems because of difficulty in treating such waste waters by conventional treatment methods, as most of the dyes are stable to light and oxidising agents (Mall and Upadhyay, 1998). The presence of even minute quantities of colouring substance makes it unsuitable for drinking or other recreational purposes due to its undesirable appearance and possible side effects (Donmez et al., 1999). The most commonly used methods for the removal of colour from dyestuffs are chemical precipitation and biological oxidation (Fernadez et al., 1995). Photo-catalytic oxidation and ozone treatment are the other alternative technologies commonly employed. However, these methods are effective and economic only when the solute concentrations are relatively high. Pithophora sp. belongs to the family of filamentous green algae. It is a common mat forming species that inhabits ponds. It clogs waterways and lakes with its large mats and filaments. It may range in colour from lime green to dark green or greenish brown. These algae possess the ability to fix and store nitrogen for their growth. When it becomes dense enough, the plant produces gas bubbles that become trapped in the water. In warmer water, it becomes buoyant and rises and floats on the water surface (Abbot and Hollenberg, 1976). Adsorption using biomass as adsorbents (biosorption) has recently attracted significant interest (Figueira et al., 2000). It has the advantages of achieving high purity of the treated wastewater through the use of cheap sorbents (Kratochvil and Volesky, 1998). Studies on various types of non-living biomasses such as algae, fungi, nut hulls and wood sawdust have shown that such materials may sequestrate dyes from aqueous solutions accumulating them within their structures; thus such materials may be used for the removal of dyes from wastewater (Matheictal et al., 1997). The sorption involves various mechanisms, mainly chemisorption, ion-exchange, adsorption by physical forces and ion entrapment in inter and intrafibrilar capillaries; oxidation / reduction reactions may also take place in the biosorbent (Yang and Volesky, 1999). The objective of this work is to study the sorption of Malachite Green dye on Pithophora sp. The algal biomass of Pithophora sp., fresh water algae, was collected from a nearby lake. The collected materials were washed with deionised water a number of times to remove dirt particles and the washing process was continued till the wash water contains no colour. The washed materials were then sun dried for 48 hours. The dried materials o were then activated at 300 C for 50 min using a muffle furnace. The activation temperature and activation time was selected on the basis of preliminary studies at different temperatures and activation times that gave maximum sorption capacity for the removal of malachite green. The activated material was then powdered using a domestic 'Sumeet' kitchen grinder. The powdered material was then sieved; the particle size in the range of 0.3 to 1 mm was used in the present study (Kumar et al., 2006) The dyes were estimated colorimetrically by monitoring their absorption in the visible region, 620 nm for Malachite Green, using Spectronic 20D+ Spectrophotometer (Spectronic Instruments, USA). Calibration graphs were prepared (1000 -8000 ppm for malachite green) and concentrations of sample aliquots were established by reference to the respective calibration graph. 0.1 g of adsorbent was equilibrated with 50 ml of desired concentrations (5, 10, 15, 20, 25 and 30 ppm) of dye solutions for a predetermined o period of time at a constant temperature of 37± 20 C on a rotary shaker (170 rpm) for equilibrium adsorption studies. After the equilibration, the carbon was separated by filtration using Whatmann No.41 filter paper, the first 10 ml of filtrate was discarded and the remaining filtrate was analysed for the unadsorbed dye concentration. pH variation studies were then performed, adjusting the initial pH of the dye solutions with dil. HCl or dil. NaOH solutions. Materials and Methods Adsorbent Estimation of dyes Adsorption experiments Removal of malachite green from its Aqueous solution by Pithophora sp. 1 2 3 3 S. Sivamani , C. Parvathi , C. Prakash and C. V. Koushik Abstract Removal of dyes from waste water is a major ecological problem. Colourants present in dyehouse effluent are responsible for environmental pollution. Removal of malachite green from its aqueous solution by Pithopora sp. has been investigated by means of a batch system. The optimum conditions were found to be (Time 10 min, pH 5 and Concentration 15 ppm) and the maximum dye removal rate was found to be 94.35%. The effects of contact time, pH and initial concentration of dye on the adsorption of malachite green by Pithopora sp. were studied. The results showed that pH and dye concentration had no significant effects. Keywords: Malachite green, Pithopora sp., Adsorption