The coupling system of magnetite-enhanced thermophilic hydrolysis-acidification and denitrification for refractory organics removal from anaerobic digestate food waste effluent (ADFE)

The aim of this study was to remove the refractory organics from high-temperature anaerobic digestate food waste effluent by the coupling system of hydrolysis-acidification and denitrification. Iron-based materials (magnetite, zero-valent iron, and iron-carbon) were used to enhance the performance of thermophilic hydrolysis-acidification. Compared with the control group, magnetite had the best strengthening effect, increasing volatile fatty acids concentration and fluorescence intensity of easily biodegradable organics in the effluent by 47.6 % and 108.4 %, respectively. The coupling system of magnetite-enhanced thermophilic hydrolysis-acidification and denitrification achieved a nitrate removal efficiency of 91.2 % (influent NO3--N was 150 mg L-1), and reduced the fluorescence intensity of refractory organics by 33.8 %, compared with influent. Microbiological analysis indicated that magnetite increased the relative abundance of thermophilic hydrolytic acidifying bacteria, and coupling system enriched some genera simultaneously removing nitrate and refractory organics. This study provided fresh information on refractory organics and nitrogen removal of thermophilic wastewater biologically.