Some Studies on Water Treatment Plant of MAHAGENCO

The coal fired thermal power station needs large amount of demineralised water and cooling water. All the thermal power station of Mahagenco use solft water for cooling and it has alkalinity ranging from 100 to 250 ppm. Demineralised water is prepared by ion exchange process and the exhausted cation resin is regenerated by hydrochloric acid and anion resin is regenerated by sodium hydroxide solution. This paper discusses two case study of the water treatment plant. (1) Detail about typical problem faced by demineralised plant operators of Mahgenco after the receipt of hydrochloric acid from chlorinated paraffin industry. This type of acid has passed the percentage purity test as prescribed by IS:265, No special test has been recommended by any standard to detect hydrochloric acid from chlorinated paraffin industry or the ground of rejection. Moreover the cost of the acid from this source is 25% cheaper than chloroalkali source. Hence detail study has been conducted by the author after gathering observation from different power station and developed simple analytical method to detect major pollutant Le. paraffin. (2) This case study is on effective utilization of waste water from soft water plant and cooling tower blow down in neutralization of acidic regeneration waste from demineralised plant. As per present practice all the wast of cooling tower and soft water plant are separately drained and used for ash disposal after being treated at effluent treatment plant or directly added. After a study on effluent of neutralization pit of demineralised plant it is concluded that most of the time effluent pH is below 6.5 which is because we are solely depend on alkali waste for neutralization, it has been observed that acid waste from demineralised plant contain 1–2% acid and below 1% alkali, which is not sufficient to neutralize the whole acid from neutralization pit. But if the waste from cooling tower which has alkalinity of 140–250 ppm is diverted or washing from soften plant having alkalinity of raw water can be effectively utilised to neutralize the acid waste and it will reduce the botheration of acid water even in case of accidental leakage. The same water can be very well used for ash sluicing.