Foreword
Central Pollution Control Board came into being in 1974 under the Water (Prevention and Control of Pollution) Act (1974). In its efforts to control pollution from industrial the Board had developed Minimal National Standards (MINA.S) for various industries and one of them is the MINAS Caustic Soda unit. The Central Board is much concerned in the control of mercury pollution emanating fram chlor-alkali (Mercury Cell based) industries in the light of Minamal in Japan (1956). It is target ted that by 1984 the mercury discharge limit as in MINA$ should be achieved by all the 23 mercury cell based caustic soda units located in various parts of India. In this context, to ascertain whether the MINAS is implemented and to r\ecommend action to taken, studies were conducted in collaboration with various State Boards in the respective units. A case study on the caustic soda unit of Hindustan Heavy Chemicals, West Bengal is presented in this report. Discharges of Ir'ercury frCIn various sources are quantified which may be of much interest to the