Effect of temperature on bio-hythane production and bioremediation of recalcitrant dye by means of two anaerobic processes

A series of batch experiments were carried out to investigate the effect of temperature on the improvement of bio-hythane production, thermodynamic characteristics, and decolorization efficiency of anaerobic degradation of C.I. acid red 88 containing wastewater. The maximum accumulated bioH 2 gas reached 0.43 l/g VS under 65 °C and the target dye was hydrolyzed with a 98% color removal. Under mesophilic temperature, bio-hydrogen production was unstable due to growing unfavorable mixed microflora. The methanogenesis bacteria activity showed better performance under temperatures ranging from 45 to 65 °C. The maximum chemical oxygen demand (COD) degradation was reached 70.2% under 45 °C, with the highest methane bioconversion that was recorded. Our results confirmed that temperature is a significant factor in improving biogas production and treated wastewater’s quality for reuse. The activation energy for hydrogen and methane is determined using regression ( R 2 , 0.95 and 0.96) to be 102.3 and 97.4 kJ/mol, respectively. Graphical abstract