Suitability of vetiver (Vetiveria zizanioides) for removal of Cr (III) from tannery effluent using floating bed and rhizofiltration systems

Various physico-chemical methods have been employed in remediating heavy metals from wastewater, but most of them are expensive. While phytoremediation, is one cost-effective and eco-friendly technology, proves to be an alternate amongst which Vetiver, a unique tropical plant, is recognized for its large biomass and dense root system and has been proven for various remediation studies. The current research was conducted to assess the potential for Vetiver rhizofiltration of chromium. A pilot study was conducted in rhizobox wherein Vetiver was grown using sand as a medium and samples were collected from rhizobox port 1 and rhizobox port 2. Subsequently, the study was upscaled to a floating bed experiment. In both studies, Vetiver were grown under 500 mg L-1 Cr (III) solution and tannery effluent had a chromium concentration of 379 mg L-1 and the results were compared to control. Between the samples collected from port 1 and 2, the removal of chromium in port 1 was recorded to be higher than that of port 2. Moreover, the removal of chromium ions from the tannery effluent was relatively higher than the spiked solution. In both the ports, the highest removal of chromium concentration was recorded in T5 (Sand + Vetiver + Cr (III) @ 500 mg kg-1) with a removal percent of 12.59 and 10.38% in port 1 and 2, respectively. Hence, Vetiver grass has a great potential in removing pollutants like chromium from the wastewater.

Metal(loid) speciation and transformation by aerobic methanotrophs

Abstract: Manufacturing and resource industries are the key drivers for economic growth with a huge environmental cost (e.g. discharge of industrial effluents and post-mining substrates). Pollutants from waste streams, either organic or inorganic (e.g. heavy metals), are prone to interact with their physical environment that not only affects the ecosystem health but also the livelihood of local communities. Unlike organic pollutants, heavy metals or trace metals (e.g. chromium, mercury) are non-biodegradable, bioaccumulate through food-web interactions and are likely to have a long-term impact on ecosystem health. Microorganisms provide varied ecosystem services including climate regulation, purification of groundwater, rehabilitation of contaminated sites by detoxifying pollutants. Recent studies have highlighted the potential of methanotrophs, a group of bacteria that can use methane as a sole carbon and energy source, to transform toxic metal (loids) such as chromium, mercury and selenium. In this review, we synthesise recent advances in the role of essential metals (e.g. copper) for methanotroph activity, uptake mechanisms alongside their potential to transform toxic heavy metal (loids). Case studies are presented on chromium, selenium and mercury pollution from the tanneries, coal burning and artisanal gold mining, respectively, which are particular problems in the developing economy that we propose may be suitable for remediation by methanotrophs. 6g_ZKsLH11vt1AExshJzH4Video Abstrac

Biotic-abiotic transformations of chromium in long-term tannery waste contaminated soils : implications to remediation / by Sara Parwin Banu Kamaludeen.

Bibliography: leaves 166-180.180, [4] leaves : ill. (chiefly col.) ; 30 cm.Determines the effect of chromium on the soil microbial community and its activity, the biotic-abiotic mechanisms involved in chromium oxidation, and phytostabilization of chromium using plants and organic amendment in tannery-waste contaminated soil.Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 200

Bioremediation of chromium contaminated environments

972-985  Bioremediation is the most promising and cost effective technology widely used nowadays to clean up both soils and wastewaters containing organic or inorganic contaminants. Discharge of chromium containing wastes has led to destruction of many agricultural lands and water bodies. Utilisation of chromium(Cr) reducing microbes and their products has enhanced the efficiency of the process of detoxification of Cr(VI) to Cr(III). This review focuses mainly on the current technologies prevalent for remediation like natural attenuation, anaerobic packed bed bioreactors (using live cells, Cr(VI) reductases or their byproducts) and use of engineered microorganisms. Treatment of wastewaters by biosorption or using biofilms and immobilized microbial cells are also discussed

Microbial role in the failure of natural attenuation of chromium(VI) in long-term tannery waste contaminated soil

Bioremediation of Cr(VI) in long-term contaminated soil environment has not been very successful due to the known reoxidation of Cr(III) to Cr(VI). Microbial role on the presence of Cr(VI) in soil samples from a long-term tannery waste contaminated site, even 25 years after cessation of waste disposal was examined. The contaminated soil, unamended or amended with 6.6% (w/w) cow manure, was incubated under 70% water holding capacity and saturated conditions. Water-soluble and exchangeable Cr(VI) declined to undetectable levels within 20 days only in saturated soil, irrespective of the presence or absence of cow manure. When the saturated soil with no Cr(VI) present was subjected to drying, Cr(VI) reappeared in cow manure-amended and unamended soil within 10 days of drying, but at levels far less than that present in the soil before saturation. When the saturated soil was autoclaved and then dried, Cr(VI) was not formed. Evidently, microorganisms are involved in the reoxidation of chromium and the resulting negligible attenuation of Cr(VI) at the long-term tannery waste contaminated site

Microbial activity and phospholipid fatty acid pattern in long-term tannery waste-contaminated soil

Sara P.B Kamaludeen, M Megharaj, R Naidu, I Singleton, A.L Juhasz, B.G Hawke, N Sethunatha