Iron-based biochar derived from waste-activated sludge enhances anaerobic digestion of synthetic salty organic wastewater for methane production

Herein, synthetic iron-based biochar was used in anaerobic digestion of synthetic salty organic wastewater for methane production. The iron-based biochar synthesized at different pyrolysis temperatures improved methane production. An optimal methane production of 551 +/- 4.0 mL/L was achieved by adding iron-based biochar prepared at 700 degrees C. The rate of hydrolysis-acidification and methanogenesis was promoted by iron-based biochar as the NaCl concentration was less than 20 g/L. However, the catalytic effect of iron-based biochar on methane production of saline wastewater failed during the NaCl concentration of 40 g/L due to the complete suppression of methanogenesis. Analyzing the methanogenic activity of iron-based biochar modified anerobic systems and characterizing the physical-chemical properties of iron-based biochar demonstrated that the iron oxides and/or zero-valent iron generated on the biochar surface increased methane production. This study highlights the potential benefits of iron-rich sludge-based biochar on enhanced anaerobic digestion and treatment of salty organic wastewater.

Automated summary

The synthetic iron-based biochar improved methane production at lower NaCl concentrations, but failed to have a catalytic effect at higher NaCl concentrations due to complete suppression of methanogenesis. Iron-based biochar demonstrated potential benefits for enhanced anaerobic digestion and treatment of salty organic wastewater by promoting hydrolysis-acidification and methanogenesis at lower salt concentrations.