Arsenic contamination of groundwater in different parts of the world is an outcome of natural and/or anthropogenic sources, leading to adverse effects on human health and ecosystem. Millions of people from different countries are heavily dependent on groundwater containing elevated level of As for drinking purposes. As contamination of groundwater, poses a serious risk to human health. Excessive and prolonged exposure of inorganic As with drinking water is causing arsenicosis, a deteriorating and disabling disease characterized by skin lesions and pigmentation of the skin, patches on palm of the hands and soles of the feet. Arsenic poisoning culminates into potentially fatal diseases like skin and internal cancers. This paper reviews sources, speciation, and mobility of As and global overview of groundwater As contamination. The paper also critically reviews the As led human health risks, its uptake, metabolism, and toxicity mechanisms. The paper provides an overview of the state-of-the-art knowledge on the alternative As free drinking water and various technologies (oxidation, coagulation flocculation, adsorption, and microbial) for mitigation of the problem of As contamination of groundwater.
A novel laccase producing Basidiomycete Peniophora sp. (NFCCI-2131) was isolated from pulp and paper mill effluent. The optimal temperature and initial pH for laccase production by the isolate in submerged culture were found to be 30 and 4.6° C, respectively. Maltose (20 g l⁻¹) and tryptone (1.0 g l⁻¹) were the most suitable carbon and nitrogen sources for laccase production. Cu²⁺ (1.0 mM) and veratryl alcohol induced maximum laccase production giving 6.6 and 6.07 U/ml laccase activity, respectively. Under optimised culture conditions, 7.6 U/ml activity was obtained, which was 2.4 times higher than that was achieved in basal medium. An evaluation of the delignification efficiency of the crude enzyme in the presence of redox mediators [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) and (1-hydroxybenzotriazole)] revealed structural changes in lignin and existence of many active centres for both chemical and biological degradation of lignin following enzymatic treatment.
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