LIFE CYCLE ASSESSMENT OF MARBLE INDUSTRY FOR CLEANER PRODUCTION TECHNOLOGY AS A POLLUTION PREVENTION MEASURE

Abstract

This study was conducted in 13 districts of Khyber Pukhtunkhwa province where marble processing have been takes place. The main goal of this study was to seek possibilities for the introduction of Cleaner Production (CP) techniques in the marble industry and to handle the wastes in environment friendly manner. For this purpose Life Cycle Assessment (LCA) technique was used. A comprehensive audit of marble processing units (MPUs) was carried out. This includes analysis of the raw materials inputs and outputs in terms of final products and byproducts. Besides, on-site treatment facility of the wastewater and its recycling in the process was studied along with the slurry recovery. This was done with the idea to reuse the water inside the units with the recovery of marble slurry powder. Analysis of waste marble slurry was done to identify its composition for ensuring its utilization in the subsequent secondary products. The analyses include chemical composition, moisture content, specific gravity, fineness and water absorption. It was estimated that a MPU needed 25-50 tonnes/day of raw marble stone. Water for cooling was required @ 15.6 to 31.8m3/day, with the electricity requirement of 385.4 to 919.2 kWh/day. Production outputs were ranged from 18 to 40 tonnes/day and 14.72-30.74 m3/day in terms of marble tiles and wastewater discharge respectively. Marble slurry waste was tested for the preparation of valuable products such as cement, dish washing powder, high strength Glass Fiber Reinforce Mortar (GFRM) and lime. After recycling of marble slurry waste in the preparation of recycled products, the necessary experimental testing of these products was also performed to check the quality according to American Society for Testing and Materials (ASTM) or international standards. Compressive and flexural strength of concrete and GFRM specimens after 28 days curing showed strength closest to control specimens and qualify the standard requirements for construction purposes. Dish washing powder prepared from 50% calcium carbonate marble slurry, 20% soda carbonate, 20% sulphonic acid and 10% soap stone shows excellent consumer‘s response in comparison of dish washing powder available in the market. Percent mean composition of lime prepared from marble slurry shows more purity index than the commercial grade. Life Cycle Impact Assessment results revealed that the wastewater of MPUs has got significant impacts on the physico-chemical characteristics of surface waters and soil. The waste produced from the marble processing can be converted into valuable products. It is therefore recommended that LCA along with Cleaner Production (CP) be made as an integral parts of Environmental Impact Assessment (EIA) process in Pakistan.