TREATMENT OF BLACK LIQUOR BY A ELECTRO FLOTATION

Abstract

Environmental pollution is one of the major problemS mankind is facing today due to rapid industrialization and urbanisation. Natural water resources, atmosphere and land has been seriously affected due to over exploitation of natural resources and increasing generation of wastes. Pulp and paper industry which is among 17 highly polluting industries in our country, discharges large volumes of solids, liquid and gaseous wastes during various stages of manufacture of paper into the environment. Pollution due to small paper mills based on agricultural residue is more serious as recovery of chemicals from black liquor, the most polluting ;...aste water, is not done due to prohibiting high cost. Proper treatment and disposal of this black liquor is one of the most serious problems faced by small paper mills and their survival and growth ultimately depend upon how this problem is solved. A recent trend has been to partially treat black liquor and then mixing with the brown and white water for further treatment. Electroflotation process offer}several advantages for such type of treatment to reduce the strength of pollution load from waste water. Till recently this process is not well established mainly due to the availability of conventional processes and not too much work has been done in this process of treatment. In this laboratory studies related to black liquor treatment through Electroflotation, a maximum of COD reduction of 45.,45%, suspended solids (5.5.) reduction of 74.24%, Dissolve Solids (D.S.) reduction of 17.26%, and Total Solids (T.S.) reduction of 31.99% obtained. It was observed that the efficiency achieved is better for S.S.: removal. It is mainly due to the better adherence of electrolytically produced gases to the floc which is responsible for such removal. It is expected that more work on the electroflotation as treatment process on other waste water shall be done and if successful in pilot plant studie