DETOXIFICATION OF PULP AND PAPER MILL EFFLUENT USING ADSORPTION

Abstract

Paper industry has played an important role in the development of human civilization. Worldwide demand for paper is likely to rise continuously due to both the population growth and the improvement in quality of life. There is huge consumption of water in the paper industry resulting in equal amount of waste water and it is amongst the highly polluting industries. It is included in the list of industries notified by the Ministry of Environment and Forest, Government of India, requiring Environmental Impact Assessment and clearance. There are various toxic compounds present in the effluent emanating from the pulp and paper mills employing chlorine or chlorine dioxide in the bleaching process. Now environmental concern has shifted from traditional parameters e.g. BOD, COD, TSS to chlorinated organic compounds containing large number of chlorinated phenols. These compounds are highly irritant and suspected carcinogens. Chemical and biological methods are being used for the treatment of pulp and paper mill effluent. Adsorption by activated carbon has been commonly used for effective and efficient removal of the pollutants. However, due to 10-15 % loss during regeneration and high cost of activated carbon, various low cost adsorbents are being tried. In the present work bagasse flyash and rice husk flyash have been used as low cost adsorbents for removal of some of the chlorinated phenols present in the bleach plant effluent. Detailed studies have been done using these adsorbents for the removal of 2,4 dichlorophenol and tetrachlorocatechol, two of the toxic compounds present in pulp and paper mill effluent. The experiments were conducted by varying the parameters affecting adsorption - adsorbent dose, pH, contact time and initial concentration. The results obtained were compared with those of using activated carbon as adsorbent for economic evaluation of the process. Adsorption studies were also carried out for removal of 4 chlorophenol and 2, 4, 6 trichlorophenol. The results and comparisons show that bagasse flyash and rice husk flyash can be used as efficient and economically viable adsorbents for toxicity removal.