EIACP (PC-RP) on Environmental Problems of Mining

A SEASONAL ASSESSMENT OF THE IMPACT OF COAL FLY ASH DISPOSAL ON THE RIVER YAMUNA, DELHI

I. CHEMISTRY

ARCHANA WALIA and N. K. MEHRA
Department of Zoology, University of Delhi, Delhi–110 007, India

(Received 23 August, 1996; accepted in final form 9 January, 1997)

The impact of fly ash on the chemistry of the River Yamuna was studied. Byproducts from a 200 MW capacity I.P. thermal power station on the west bank of the River Yamuna, Delhi are largely from coal combustion (fly ash) and are disposed of as a slurry to offsite ash ponds. Many elements associated with fly ash are soluble and become available to the biota. A twoyear survey was made of the seasonal variations in limnochemical features in the nonimpacted and the impacted segments of the river receiving fly ash effluent and the ash treatment ponds. Conductivity, TDS, DO, hardness, sulphate and nitrate increased significantly in the receiving waters over background values. The reverse was noticed for free CO₂, alkalinity and phosphate. Changes in some other parameters were insignificant. Fly ash effluents from the ash ponds significantly increased the concentration of some elements, viz., Al, Sb, Bi, Cd, Cr, Co, Li, Mn, Mo, K, Si, and Zn in river water. Generally, the highest concentration of most parameters were recorded in the ash ponds. This investigation was helpful in assessing the effect of wet ash disposal on the river limnology and understanding the solubility of various elements in the ash ponds.

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