Performance of sewage treatment plants: coliform reduction

The predominant cause of water pollution in India is the presence of Fecal Coliform, mainly due to large amount of untreated sewage discharged into the water bodies. Many a times, even if treated sewage is discharged into a water body, still high Coliform levels remain as a significant pollution issue. Although, conventional treatment technologies also reduce the Coliform level significantly, still these levels are high enough to pose a health hazard in the receiving water bodies. For regulation of pollution, Central Pollution Control Board (CPCB) has been providing Minimal National Standards (MINAS) for all the important pollutants. These standards are used by the State Pollution Control Boards/ Pollution Control Committees to regulate pollution in their respective States/UTs. The techno-economic feasibility of MINAS is ensured through detailed studies on the performance of various technological options. Keeping this in mind for setting Coliform standards, CPCB with the help of Indian Institute of Technology, Roorkee and Anna University, Chennai carried out a detailed study on performance of all the prevailing treatment technologies in terms of Coliform reduction. The results of the two Studies are presented is this Report. IIT Roorkee had also carried out experiments on measures for further reduction in Coliform level after the conventional treatment. The two Institutes also compiled the information from the world literature on global technological options for Coliform reduction in sewage.