A novel enhanced anaerobic biodegradation method using biochar and Fe(OH)3@biochar for the removal of nitrogen heterocyclic compounds from coal gasification wastewater.

Three identical lab-scale sequencing batch reactors (SBR) were operated for 120 days for raw (R1), biochar (R2), and Fe(OH)3@biochar (R3) enhanced anaerobic degradation of selected nitrogen heterocyclic compounds (NHCs). The occurrence of Fe-OH ensured the successful attachment of Fe(OH)3 to biochar as evidenced by the Fourier transform infrared (FTIR) spectra of biochar and Fe(OH)3@biochar. Acute biotoxicity experiments revealed that enhancing biochar and Fe(OH)3@biochar effectively decreased the toxicity of microorganisms. Additionally, the introduction of biochar and Fe(OH)3@biochar improved the settling performance of anaerobic sludge. Further, it was concluded that enriched Longilinea and Comamonas might be the major genera that function to degrade selected NHCs in anaerobic conditions.