Design of Eco-Friendly Geo-Composite Liner for Fly ash Ponds

This paper aims to design of geocomposite liner for fly ash ponds. Our country has many thermal plants, which generates huge amount of flyash as a waste and their disposal require some of the crucial treatment and engineered flyash pond. The problems from coal based thermal plants is disposal of such flyash. In the present research, Clayey soils, Sodium bentonite and black cotton soils used as a liner for fly ash pond, instead of HDPE sheet to reduce the heavy metal contaminants leachate. Recent GCL, HDPE or Geocomposite liners as bottom lining layers are a suggestive solution for preventing toxic materials from seepage into the surrounding areas. The obtained results of this research indicate that the more percentage of concentration of heavy metals like Arsenic, lead, cadmium and chromium are retained in sodium bentonite layer than the black cotton soil. Hence it is, recommended that among the different liners, sodium bentonite is the most appropriate geocomposite liner, as it’s self-healing and swelling properties provides more retention capacity of toxic heavy metals. The present invention relates to a geocomposite liner system for fly ash pond to reduce the leaching of toxic metals in ground water. The geocomposite liner system comprises of at least one fibrous layer having a layer of sodium bentonite material; a non-fibrous layer mechanically and non-adhesively affixed between fibrous layers. A suitable thickness of bentonite clay is encapsulated between the fibrous and non-fibrous layers, it can retain the Arsenic, Cadmium, Chromium and Lead metals in it. This Geo composite liner is most suitable, economical and easy to install over CCLs and GCLs.

Synthesis and Characterization of Mullites From Silicoaluminous Fly Ash Waste

Fly ash is considered one of the major hazardous pollutants around the globe. Every year a million tonnes of fly ash is disposed of into the fly ash ponds which are major sites of pollution. The major fractions of fly ash are silicates, aluminates, and ferrous substances followed by minor traces element oxides. The aluminates and silicates comprise of 70% of the fly ash. The aluminates and silicates are present in fly ash in the form of crystalline mullites and sillimanites. Mullites being inert and crystalline are retractile to mineral acids. So, here the authors have reported a novel and simple step for the recovery of all the major elements of fly ash along with recovery of mullites by using hydrofluoric acid at room temperature. The method comprises of treatment of fly ash with diluted hydrofluoric acid for 12 hours under agitation. The recovered white color mullite powder, rod shaped of size 90-300 nm, was analyzed by the sophisticated instruments for the confirmation of the mullite particles.

Bioleaching of trace metals from coal ash using local isolate from coal ash ponds

Bioleaching of chromium, copper, manganese and zinc from coal ash were investigated using isolates from coal ash ponds particularly Psuedomonas spp. Six (6) different coal ash ponds were examined however, after initial screening Psuedomonas spp. were only present in three (3) coal ash ponds. Among the three coal ash ponds, results showed that eight (8) putative Pseudomonas spp. isolates were present that were identified using the Polymerase Chain Reaction (PCR). Using the eight putative Pseudomonas spp. for bioleaching at optimum conditions and 15 days, the pH value ranges from 8.26 to 8.84 which was basic in nature. Moreover, the maximum metal leached were 8.04% Cr, 12.05% Cu, 4.34% Mn and 10.63% Zn.