Dechloridation of Treated Tannery Effluent by Using Leaves of Plants

The present study deals with the dechloridation of treated tannery effluent by using plant leaves. The effluent after treatment, which is let out from the Common Tannery Effluent Treatment Plant (CETP) into Senkulum lake, Dindigul, Tamilnadu, was collected for the study. The physico-chemical characteristics of the treated tannery effluent were analysed. The pH value of effluent was 8.04, which slightly exceeded the recommended value. The electrical conductivity was 12,500 micromhos/cm, which was higher than the permissible limit. The value of hardness was 2210 mg/L. Out of the three cations tested, i.e. sodium, potassium and calcium, the sodium was 1275 mg/L followed by potassium (76mg/L) and calcium (295mg/L). The chloride content was higher (12,652 mg/L) in the tannery effluent. Leaves of plants such as Cynodon dactylon, Psidium guajava, Azadirachta indica, Cassia tora and Cassia angustifolia were used for the study. An adsorption kinetic study was performed with different weights of adsorbents (100-500 mg/100 mL), temperature (20- 60°C) and pH (4-10), for chloride adsorption with different contact times (30 min, 1 hr, 2 hr). The Cassia tora leaves adsorbed maximum chloride compared to the leaves of other plants with a maximum weight of 200mg of adsorbent/100 mL, temperature of 40°C, pH 10 and contact time of 2 hours.