Phenols are widely used in the manufacturing of various chemicals like pesticides, herbicides, biocides and dyes. The effluent generated from these industries is heavily contaminated. Different routes used for the removal and recovery of phenols from the waste water include oxidation, biodegradation and recovery by resins. The oxidation method requires external addition of chemicals to the effluent stream, for the oxidation of phenols. These chemicals are very expensive and effluent requires further treatment for removal of these added oxidizing chemicals. In the biodegradation method phenols are biodegraded with the help of activated sludge. In this method the microorganism in the activated sludge process degrade the phenols to form carbon dioxide and water. But the process requires high energy and becomes economically non-feasible when there is high concentration of phenol in waste water. To overcome this problem one can recover phenol from effluent by using adsorption technique. This method also reduces CO2 emissions from the bioreactors and curtails the over all operation cost of bioreactor.
Material and Methods:
A laboratory experiment was carried out by using cationic resin in two separate glass columns and 200ml of resin was packed in each glass column. The effluent of 6000 mg/l of phenols concentration was fed from the top at the rate 6 ml / minute. The elute was collected in a glass beaker of two litre capacity from the first column and was again passed through second resin column. A composite sample of elute from first and second columns were analyzed on Gas Chromatography. Resins adsorb phenols on its surface. Maximum adsorption can be achieved by regulating the rate of elution. This concentration of phenols can be reduced below 100 mg/l by passing through similar second resin column. This will help in lowering down the initial concentration and effluent treatment cost required for biological treatment.
The biological treatment of phenols requires higher capacity of bioreactors which ultimately results in huge energy consumption for aeration. The result and overall cost benefit analysis of the treatment plant before and after recovery of the phenols show that there is a huge difference of
र 23,50,000 per day for the treatment of 25KL effluent, if it is biologically treated after recovery of the phenols. Recovery will also reduce the electrical energy consumption from 358KW to 180KW per day. The recovery and recycling of phenols will save र 304,000 per annum.
Recovery of phenols by resin column is therefore economically feasible and eco friendly method.Bandela N.N. and Deshpande D.M., Department of Environmental Science, Dr Babasaheb Ambedkar Marathwada University, Aurangabad