Utilization of lime sludge waste from paper mills for fish culture

Lime sludge (mud) waste from a paper mill at Jagiroad, Assam (Hindustan Paper Corporation Limited) can be used as a cheaper alternative source of liming for management of acidic water in the fish ponds of Assam. Lime sludge waste has no toxic substances, but contains 66.5% calcium carbonate. To maintain the alkalinity level of water, 1.5 times more lime sludge waste is required compared to pure lime. Parameters like pH, conductivity, free carbon dioxide, total hardness and dissolved oxygen are increased due to application of lime sludge waste from the paper mill, which are beneficial to the fish as well as fish food organisms. The heavy metals found in the lime sludge waste were below permissible level. Lime sludge has no adverse impact on growth and development of fish, rather it has some beneficial effect on production of fish.