Study on soil bio-remediaton for preventing groundwater contamination of chromium bearing leather processing waste dumping sites

Around 2300 tanneries in India produces 6000 tones of solid waste per annum, that includes 15000 tones of chromed leather shavings waste. This contain Chromium. Cr (VI) compounds used in leather processing which are highly water soluble, toxic, carcinogenic and a potential ground water contaminant. The MoEF have classified the chromium bearing solid wastes in the hazardous waste category that necessitates the disposal mechanism such as landfilling, stabilization, solidification etc., Many advanced chromium treatment methods were emerged that includes physio-chemical extraction and phytoremediation , but did not give complete solution to the problems. However, the bioremediation is one of the promising technology that is expected to play an important role in soil waste clean-up although, still in the preliminary stage. This is attributed to lack of proper understanding on integrating the geochemistry, geomicrobiology, geomorphology with soil stratification and mode of leachability. Therefore, this study is focused to evaluate the soil profile, geochemistry, geomorphology, biochemical transformation of cationic and anionic balances, specific organism's and their phylogenies for chromium degradation in Cr dumped sites. The present paper describes the important process of soil bioremediation based on the existing literatures, identified the gap in research for mobility of chromium degrading bacteria at different, compacted, non-compacted, porous and non-porous soil strata. A standard bioremediation protocol is the need of the hour to be developed for soil bioremediation in a confined and unconfined soil which can further be extended to other metals/salts such as (Ni, Fe, Zn, Cobalt) in contaminated waste dumping sites.Therefore, the laboratory and field level natural investigation on chromium contaminated waste dumping sites and sparging/injecting clusters of micro organisms that are capable of degrading chromium with a rich carbon source in the soils near Chromate industries at Ranipet, TamilNadu has been proposed as a complete detoxification of chromium before it reaches the groundwater.