Recycling of liming solution

Abstract

Pollution is one of the problems facing human being and if not controlled it will gradually lead to complicated environmental problems. According to current legislation on the environment tanners are required to reduce all kinds of pollution (solid wastes, dissolved or suspended substances in effluents, etc) The beamhouse operations cause the highest pollution during the leather manufacturing processes. Data provided by the leather department center indicated that sodium sulphide and lime are responsible for most pollution (55%) of the total pollution and 84% of the BOD, 75% of the COD, 92% suspended solids and 100% of toxicity. The aim of this work is to reduce the pollution load by recycling of the liming solution and at the same time reduce the amount of chemicals used in other processes and reduce the cost. Recycling process was carried out by adding a make up of sodium sulphide, lime and water to the used liquor to raise the concentration to its initial level. Chemical analysis and experimental work indicated that the save of sodium sulphide, lime and water was 60%, 40% and 90% respectively and the leather produced had the same properties compared with that produced by conventional method.