POLLUTION CONTROL CASE STUDY : INDUSTRIAL EFFLUENTS TREATMENT AT MRL, CHENNAI

A leading petroleum refinery, The Madras Refineries Limited (MRL) located in Chennai has taken important steps in managing the effluents discharging efficiently.

The MRL has two efficient treatment plants designed to meet IS2490 quality control standards. The Ministry of Environment and Forests has developed an industry oriented standards called MINAS (Minimum National Standards) as per the Environment Protection Act, 1986.

At the new plant, the treatment facilities consists of three streams.

1. The first is cooling water treatment.

2. The second is treating sour and merox water and

3. The third is for treating floor wash and stream water and to remove oil.

The three efficient streams from the refinery contain the following contaminants.

1. Process and utility stream : The contaminants are oil, grease, hydrogen sulphide, phenols, acids and alkalis.

2. The storm and wash water stream : Oil and grease.

3. The general purpose stream : Waste water, solids, organics and bio-organisms.

The MRL has taken bold initiatives and concentrated on the water management to meet the water requirements of the factory due to decreasing sub-soil water.

1. MRL has installed non-chromate type treatment facility to avoid chromium, a heavy-metal, mixing with the effluent.

2. Facilities for recycling to help reduce the quantum of pollutant discharge are also installed.

3. Further, MRL, went in for installation of tertiary treatment plant to treat secondary treated sewage of the city at Madras Metropolitan water supply and Sewage Board, to reuse the water. This facility, though costed heavily (rupees twenty five crores) and it has solved the water problem in summer. In Installing this unit, it was ensured that the quality of ground in the area was not affected.

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