Executive Summary : | Objective: To investigate into preparation / utilization of Permeable liner for disposal of coal ash in ash disposal ponds. The objectives are as follows. To evaluate its efficiency to prevent leaching of contaminants to groundwater. Summary: Huge quantity of coal ash produced in thermal power plants in India is disposed of with high environmental risk. Utilization of fly ash at different sectors has picked up but still few percentage of it is being utilized and power plants are compelled to dispose fly ash in ash ponds. Disposal of ash into ash ponds lends to environmental issues like ground water and surface water pollution. For this reason, Central Pollution Control Board has issued norms on providing plastic liner over the entire bottom of ash ponds and upstream faces of the ash dykes. The disadvantage of plastic liner is that the drainage becomes very difficult and as a results the deposited pond ash could not get dried up to the same extent as compared to the pond without plastic liner. In the present proposed study zeo-synthetic permeable liner made up of fly ash zeolite will be used in the laboratory to know its effective utilization in ash ponds. The prepared zeolitic material, which will provide a cost effective permeable liner that can be used in ash disposal ponds before disposal of huge quantity of fly ash into it. According to available literature it appears that few research work have been carried out to prepare zxeolitic material from fly ash. Zeolitic material prepared from fly ash will have unique adsorptive, molecular-sieve and ion exchange capacity. It will have better efficiency for prevention of contamination of ground water as compare to naturally available clay material. Fly ash is an agglomerate of micro spheres, which are mainly composed of Si and Al with minor amount of Fe, Na, K, Ca, P, Ti, and S. The major mineral compounds are amorphous aluminosilicate (glass) but other crystalline minerals are also present, such as mullite, quartz, hematite, magnetite, lime, anhydrites and Feldspars. These chemical, mineralogical and textural features make fly ash, a very suitable starting material for zeolite synthesis. The conversion of fly ash into zeolite not only eliminates disposal problem but also turns an otherwise waste material into a useful one. In case of groundwater contamination remediation, permeable reactive barriers are put on the direction of groundwater flow. The chemically reactive barriers or in situ treatment zones are permeable zones emplaced within the aquifer, which reacts with contaminants as contaminated ground water flows through the zone. Fly ash zeolites are the main reactive constituent for grouted screens or fly ash zeolite geotextile casings or geosynthetic fly ash zeolite.
In the proposed study fly ashes will be collected from Thermal Power Plants of NTPC. It will be characterized and utilized for synthesis of zeolite. In the laboratory bench scale experiment using one fly ash filled in PVC Vat with fly ash zeolite as permeable liner and the other fly ash filled in PVC Vat without permeable liner will be carried out. Leaching studies of fly ash filled Vats on weekly basis and analysis of different contaminants in the leachate water collected from the bottom of Vats will be done. For leaching different liquids like distilled water, acidic water etc will be used. Analysis of different water quality parameters will be carried out according to different IS Standards. The generated data in the laboratory will be processed and will be evaluated through the computer and empirical model will be developed to know the efficiency of zeolite to prevent the leaching of contaminants through fly ash filled Vats. Finally from over all experiments evaluation of cost effective and suitability of zeolitic material as permeable liner for disposal of fly ash in ash disposal ponds will be carried out. |