Enhancement of Solubility and Biohydrogen Production from Sewage Sludge with Lime Mud Filtrate

This work has been performed to investigate the use of lime mud filtrate (LMF) pretreatment to enhance hydrogen (H-2) evolution from sewage sludge (SS). The SS samples were pretreated with LMF (pH 8.0-11.0) at 55 degrees C for 48 h, prior to the H-2 fermentation. The maximum H-2 yield of 38.30 ml/g-VS (volatile solid) was obtained from the SS pretreated by LMF pH of 10.0, with the corresponding lag time of 3.10 h, which was well described by the modified Gompertz model. Adequate pH of LMF facilitated the solubilization of SS and the release of organic matters, providing adequate substrates for subsequent bio-H-2 evolution. The soluble chemical oxygen demand was increased from 25.0 to 91.7%, as compared with the control test without LMF soak. However, further increase in pH of LMF could decrease the concentration of available substrate, thus reducing the H-2 yield. This technique revealed sustainable waste management and energy recovery.