Effect of electroplating industrial waste on “available phosphorus” of soil in relation to other physicochemical properties

Abstract

Unorganized land disposal of industrial wastes contaminates land and ground water. The Wazirpur Industrial area of Delhi, a metropolitan city, generates highly acidic (pH 2 - 3.8) and toxic waste, and disposal remains a perpetual problem. This waste contains a high quantity of macronutrients as well as heavy metals because major industries are involved in metals finishing. Wastes of these industries were mixed with municipal waste at roads. Hence a study was undertaken to verify the suitability of land disposal of this toxic waste. The waste was first treated with three doses of lime (0, 0.5 and 1%) and then mixed with two types of soils from two different locations in three different proportions viz. 10, 20 and 30%, maintaining soil moisture level at 50% of water holding capacity. These samples were incubated for 120 days. All three waste amendments resulted in an increase in available phosphorus (AP) in both waste- amended soils as compared to the control soils. It is statistically significant at p = 0.05 level. During the 120 days of incubation highest value (36.41 ± 0.01 ppm for site 1 soil and 30.40 ± 0.03 ppm for site 2 soil) of available phosphorus had been found at 20^th day of incubation for both the soils. Lime treatment at the rate of 0.5% gave in 10 and 20% treatments significantly positive result as compared to 0 and 1% treatment. Only in 30% waste amendment 1% lime treatment gave better amount of available phosphorus (27.77 ± 0.01 ppm and 24.84 ± 0.03 ppm for site 1 and site 2 soils respectively). The finding of the study evident that 0.5% lime treated 10% industrial waste can be used as manure for soil. The result is of further interest from a plant nutrition standpoint since the amount of potentially mobile-P measured in this study could be related to the amount of available phosphorous required for crop growth.

Key words: Industrial waste, land disposal, incubation study, available phosphorus.