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.

In recent years, there has been increasing interest in the use of biomass from microbialsources, particularly the microalgae, to absorb multimetal ions in the waste water.The other type of treatment like ion exchange, evaporation, precipitation, membrane separation etc.are too expensive to treat low levels of heavy metal in wastewater. This work demonstrated the biosorption of a mixture of heavy metals solution with silica gel immobilized micro algae Comparison of metal uptake in single and multi-component aqueous solutions of Cu-Zn was discussed. The results suggested that there should exist a competitive adsorption for the binary mixture solution as the adsorption capacity for the primary heavy metal often dropped with the introduction of the secondary heavy metal. The adsorption capacity was also found to decrease for the cases of binary adsorption. The biosorption equilibrium data obeyed Langmuir and Freundlich model in the concentration ranges studied.The preference of investigated biosorbent for metals is as follows Cu>Zn. The sorption processes were found to be slower in multi-component than those in the single-component metal solutions. Concerning copper, and zinc, no significant removal efficiency could be noticed between single and multi-component aqueous metal solutions in the presence of NO 3 and SO 4 anions. On the contrary, presence of chloride ions significantly decreased efficiency of metal biosorption.. The presence of Ca and Mg ion did not affect the adsorption of Cu ion whereas these ions considerably affect the adsorption of Zn ion. This finding is highly important for the design of the adsorption system and it can be used for metal uptake in waste water treatment

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