The coloured effluents produced from different industries, such as textile, plastics, printing, cosmetics, leather and paper, are extremely toxic and a tremendous threat to the aquatic organisms and human beings. The removal of coloured dye pollutants from the aqueous environment is a great challenge and a pressing task. The growing demand for low-cost and efficient treatment approaches has given rise to alternative and eco-friendly methods, such as biodegradation and microbial remediation. This work summarizes the overview and current research on the remediation of dye pollutants from the aqueous environment by microbial bio-sorbents, such as bacteria, fungi, algae, and yeast. In addition, dye degradation capabilities of microbial enzymes have been highlighted and discussed. Further, the influence of various experimental parameters, such as temperature, pH, and concentrations of nutrients, and dye, has been summarized. The proposed mechanism for dye removal by microorganisms is also discussed. The object of this review is to provide a state-of-the-art of microbial remediation technologies in eliminating dye pollutants from water resources.

To exploit photocatalytic performance is one of the worthiest efforts for expanding the application of carbon dots (CDs) owing to their low-cost starting materials, facile preparation and simple operation without secondary pollution. Herein, novel biomass-based CDs (Bio-CDs) were successfully synthesized from waste palm powders by using one-step hydrothermal method under the facilitation of thionyl chloride on carbonization process and doping effect. The resultant Bio-CDs exhibited quasi-spherical shape with an average size of 3.54 nm and displayed blue-emissive fluorescence with excitation-dependent behavior. Benefiting from the S and Cl co-doped structure and small size effect, the synthesized Bio-CDs possessed high photocatalytic activity towards the degradation of organic dyes under visible light. The degradation of the Rhodamine B was nearly 71.7%, while the Methylene Blue was almost decomposed completely (ca. 94.2%), which make the Bio-CDs to be a hopeful candidate as photocatalyst for the reduction of organic pollutants.