A composite approach for remediation of cane distillery spent wash using chitosan modified biomass, electrolysis, and Oscillatoria boryana

A cost effective multistep bio-physicochemical method comprising adsorption on carbon, banana pseudo-stem (BPS), and modified chitosan hydrogels (MHPS) as adsorbents, bioremediation using Oscillatoria boryana (OB) and constant current electrolysis was employed successfully to remove oxygen demanding organic wastes, color, total dissolved solids (TDS), melanoidin, and acidic/basic impurities from distillery spent wash (DSW). The adsorbent were characterized for their structures [Shimadzu FTIR (Fourier transform-Infrared spectroscopy)-8400S], thermal stability [TGA (Thermogravimetric analyzer)-Q 500 V20.0 Build 36] and surface morphology [ZEISS EVO series SEM (Scanning Electron Microscopy)-EVO 50]. The percentage color reduction by visible spectrometry and residual coloring matter on platinum-cobalt color unit scale were found to be 97.2% and 250 ppm, respectively till OB bioremediation stage. The remaining residual color (2.8%) was removed in the subsequent electrolysis (1.95%) and adsorption on MHPS (0.85%) stages. The net percent reduction in color (>99%), COD (Chemical Oxygen Demand) and BOD (Biochemical Oxygen Demand) in the present composite approach for DSW treatment were found to be much higher than the reported values. Analysis of the adsorption data for the synthesized activated carbon through Langmuir and Freundlich isotherm models revealed Langmuir adsorption isotherm with pseudo-first-order kinetics. The evaluated thermodynamic parameters (Van't Hoff plot) for adsorption revealed that the adsorption was spontaneous and exothermic. (C) 2016 Wiley Periodicals, Inc.