Textile industries use dye such as Rhodamine B, Brilliant Red and Reactive Orange for the fabrics. Thus the colour of the effluent even after the normal treatment is not within the standard to discharge into the environment. A study was conducted to identify suitable bio-sorbents and to optimize the conditions for selected bio-sorbent to reduce the colour of treated waste water (TWW) from a textile industry. Sieved and air dried sawdust from Rubber (Hevea brasiliensis), Trincomalee wood (Berrya cordifolia), and Breadfruit (Artocarpus altillis) timber were tested with TWW. Rubber sawdust showed a better performance in colour removal than the sawdust from Trincomalee wood and Breadfruit. In order to optimize the conditions with the rubber sawdust, colour removal efficiency of TWW was measured at different pH, sawdust amount, initial dye concentration and different contact times. Sorption data was modelled by Langmuir and Freundlich adsorption isotherms for each dye; Rhodamine B, Brilliant Red, Reactive Orange. Results showed that the best performances of adsorption of dye into Rubber sawdust was obtained at 5 g/L sawdust dosage with 6 minutes contact time up to 0.2 ml of 0.5 M dye concentration under pH 2. Adsorptions of acidic dye (Brilliant Red) and anionic reactive dye (Reactive Orange) followed the Langmuir isotherm. Sorption of cationic dye Rhodamine B was better represented by the Freundlich model. It is recommended to use the sawdust of rubber to remove the colour in wastewater in acidic condition and neutralize the effluent before discharge to the environment.
Tropical Agricultural Research Vol. 26 (4): 666 – 676 (2015)