Physico Chemical Characteristics of Paper Mill Effluents and Its Treatment Process

Paper mill need high purity water to get pure cellulose, high bright paper, caustic and lime. The proportion of water to chemicals and fibers is indicated by solid percentage and consistency. The process involved are debarking, chipping of woods, wet piling of bagasse, cooking, washing, screening, cleaning, dewatering and bleaching in pulp making, stock proportioning, cleaning, screening, sheet forming, drying and broke handling in paper making and evaporation of black liquor, combustioning of black liquor in recovery boilers, causticizing in soda recovery process. In each and every stage of process effluents were generated and their physico-chemical properties, effluent load varied due to the presence of organics and inorganics. The effluent generated have high dissolved solids, high COD and BOD, dark brown color, acidic and alkaline pH. The effluent adversely affects surface and ground water, fertility and texture of soils and also affects fisheries and aquatic flora and fauna. In this presence study samples were collected covering from selected unit operations of the paper mill and their physico-chemical characteristics were analyzed. The final outlet was treated with alum, charcoal, fly ash and neutral sodium silicate. The study shows that the treated effluent have good reduction in total solids, total dissolved solids, total organics, COD, BOD and results in colorless effluent.