STUDIES ON TREATMENT OF BLACK LIQUOR BY ANFLOW FILTER

Abstract

Paper and pulp industry has developed manifold during the recent past. It is one of the major pollution industry, wherein the "black liquor" emanating from pulping process has the maximum pollution potential. In most of the large paper mills, the soda-recovery system is followed' and black liquor does not join the effluent stream. In small paper mills (SPM),, however the recovery process becomes too costly to afford. Present practice in most of the mills (SPM) is to mix the black liquor to the rest of waste and subject to the treatment. However, this practice leads to higher cost of treatment, fluctuations in characteristics of the input to Effluent Treatment Plant and thus lower overall efficiencies. A recent trend has been to partially teat black liquor and then mixing with the brown and white water for further treatment. All anaerobic systems viz. An. Lagoons, UASB reactors, Digesters are being studied for their applica-tions in field, Anaerobic Filters, through of recent origin are being recommended. In this laboratory studies related to black liquor treatment through Anaerobic Filter, it was observed that a maximum of COD reduction of 37.1%, Suspended Solids (S.S.) reduction of. 96.5%, Dissolved Solids (D.S.) reduction of 28.5%, and Total Solids (T.S.) i'duction of 38.5% is possible. Also it was observed that at low organic loading the efficiency achieved is better. The bio-gas produced has methane percentage varying as a function of organic loading. It is expected that more work on the anaerobic filters as treatment units for black liquor shall be done and if successful in pilot plant studies, will be implemented in practice. ( iv ) CONTENTS