Effect of asparagine, corncob biochar and Fe(II) on anaerobic biological treatment under low temperature: Enhanced...

To ensure the efficiency of anaerobic biological treatment technology at lower temperature will expand the application of anaerobic reactor in practical industrial wastewater treatment. Through a batch experiment, asparagine, corncob biochar and Fe²⁺ were selected as strengthening measures to analyze the effects on the anaerobic sludge characteristics, microbial community and functional genes in the low temperature (15 °C). Results showed that after 21 days, asparagine began to promote chemical oxygen demand (COD) removal by the anaerobic treatment, with highest COD removal rate (81.65%) observed when the asparagine concentration was 1 mmol/L. When adding 3 g biochar, 25 mg/L Fe²⁺, and the combination of biochar and Fe²⁺, the COD removal rates reached to 82%, 92% and 97%, respectively. In the presence of asparagine, both biochar and Fe²⁺ alone or in combination increased the activity of protease (16.35%-120.71%) and coenzyme F₄₂₀ (5.63%-130.2%). The relative abundance of Proteobacteria and Methanobacterium increased in the presence of biochar and Fe²⁺. In addition, the KEGG results showed that the combined addition of biochar and Fe²⁺ enhanced bacterial replication and repair and promoted amino acid metabolism of archaea.