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Among the industries generating hyper saline effluents, tanneries are prominent in India. Hyper saline wastewater is difficult to treat by conventional biological treatment methods. Salt-tolerant microbes can adapt to these conditions and degrade the organics in hyper saline wastewater. In this study, the performance of a bench scale aerobic sequencing batch reactor (SBR) was investigated to treat the tannery wastewater by the salt-tolerant bacterial strains namely Pseudomonas aeruginosa, Bacillus flexus, Exiguobacterium homiense and Styphylococcus aureus. The study was carried out under different operating conditions by changing the hydraulic retention time, organic loading rate and initial substrate concentration. From the results it was found that a maximum COD reduction of 90.4% and colour removal of 78.6% was attained. From this study it was found that the salt-tolerant microorganisms could improve the reduction efficiency of COD and colour of the tannery wastewater.

Efficient and economical treatment for color removal in the effluent of dyeing units and the dyestuff production units have always need an emerging technologies. In general physical methods such as adsorption, ion exchange and filtration/coagulation methods, chemical methods like ionization, Fenton reagent, photo catalytic & biological processes namely aerobic/anaerobic degradation, biosorption are used for dye removal. Adsorption using solid materials (i.e.) adsorbents, considered as an effective process for color removal, because of its higher efficiency over other processes. Researchers made an attempt to use various non-conventional, low-cost, naturally-occurring biomasses as adsorbent, which may be mineral, organic or biological materials. These include fruit peels, seeds, leaves, bark, sawdust, straw, ash sludge and other materials that are available in abundant quantity. The various methods showed the color removal capability of adsorbents; mainly based on the processing methods and the variety of dye. In this review, various dye adsorbents and their capacity for removing the dyes from various effluents is highlighted.

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