Environmental Impact of Ash Pond of a Thermal Power Plant on Groundwater Quality

Ash pond is the term associated with thermal power plants where the ash is disposed of in a low lying area by mixing with water. The water percolates into the subsoil and ash after sun drying will be used for recycling purposes. The physico-chemical properties of groundwater are affected due to wet disposal. The groundwater samples collected from the surrounding villages near an ash pond of a thermal power station (TPS) near Vijayawada were investigated for possible contamination of groundwater. Total dissolved solids, total hardness and sulphates were found to be major quality parameters in the samples. The groundwater quality in majority of sampling locations is not suitable for drinking. Further, leaching studies were performed in laboratory to assess the variation of leaching properties from the ash with respect to time. The leachate was tested for selected physico-chemical parameters and analysed for their variation with time. It is found to have high TDS, turbidity and total hardness and confirmed that leaching is a slow process. A sample survey was conducted in all the villages where water samples were collected. It is noticed that the villagers are facing problems with the ash pond water contamination and dry ash rising into atmosphere. However, the local groundwater is helpful for irrigation purposes due to the low values of sodium absorption ratio and residual sodium carbonate index. The utility of flyash from ash pond was tested for its removal of fluoride. The results of treatability studies indicated that at low concentrations of adsorbent dose, a 70% removal of flouride from synthetic fluoride solution and 50% removal from field sample.