Abstract:
Solid waste is a major challenge to developing countries. Urban areas of Pakistan are estimated to produce 40,000 tons /day and are projected as 75,000 tons /day by 2025. Almost 60 % of generated waste is collected and dumped in open area as a common practice. Till date there is no operational sanitary land fill site in the country expect one in Lahore. Thus, waste dumping poses serious threat to community health, groundwater, surface water resources, soil and reduced plant diversity. More than 1000 chemicals have been identified in groundwater contaminated by landfills leachate that can pollute the environment. The objective of this study was to develop a bio retention media that can filter pollutants from the leachate. For the said purpose, vermi compost was chosen as a bio-retention media, but the problem is compost itself leach organics and phosphorus along with copper and other heavy metals. To deal with the leaching, TiO2 nano-particles immobilize on silica sand were used as an additional layer that has excellent sorbtion capacity along with photo catalytic capability. A leaching experiment was designed in a leaching column and was irrigated with original leachate collected from dumpsite of Islamabad. Result of this study concluded that TiO2 nano particles (NP) were successfully immobilized on the silica sand and addition of a layer of NP significantly improved leachate quality. Immobilized NP reduced the contaminant flow from the compost itself. Moreover, UV application on TiO2 NP decreased the nitrite leaching from the compost. Also significantly reduced organic carbon and ortho-phosphorus in addition to the leaching of metals like lead and chromium.
