Performance evaluation of low cost adsorbents in reduction of COD in sugar industrial effluent

Studies on reduction of chemical oxygen demand (COD) in effluent from sugar industry have been carried out by employing different absorbents optimizing various parameters, such as initial concentration of adsorbate, pH, adsorbent dosage and contact time. Experimental studies were carried out in batches using metakaolin, tamarind nut carbon and dates nut carbon as adsorbents by keeping initial adsorbent dosage at 1 g l−1, agitation time over a range of 30-240 min, adsorbent dosage at 100-800 mg l−1 by varying the pH range from 4 to 10. Characterization of there adsorbents were done using techniques such as Fourier transforms infra red spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The experimental adsorption data fitted well to Langmuir and Freundlich adsorption isotherms. The isotherms of the adsorbents indicate appreciable adsorption capacity. Higher COD removal was observed at neutral pH conditions. Studies reveal that maximum reduction efficiency of COD takes place using metakaolin as an absorbent at a dosage of 500 mg l−1 in a contact time of 180 min at pH 7 and it could be used as an efficient absorbent for treating sugar industrial effluent.