Optimizing anaerobic digestion of Chinese liquor brewing wastewater: A cost-effective and high-performance approach

Abstract

The low pH and intricate pollutants in Chinese liquor brewing wastewater (CLBW) pose significant challenges for effective anaerobic digestion (AD) treatment. Granular activated carbon (GAC) can facilitate direct interspecies electron transfer (DIET) and enhance the system’s tolerance to high OLR and low pH. This study investigates a novel approach combining GAC addition and slight influent pH adjustment, which can enhance AD performance of CLBW with reduced alkali need. The synergistic effects and underlying mechanisms remain unclear. The results revealed that the reactor (R20-1), amended with 20 g/L GAC and the influent pH adjusted by adding 1 g NaOH/L_influent, while the non-GAC reactor failed rapidly at an initial OLR of 3.4 kg COD/(m³∙d). Microbial community analysis revealed that Prevotella was enriched at 12.7 kg COD/(m³∙d)), whereas Parabacteroides dominated at high OLRs > 15.9 kg COD/(m³∙d). Key archaea such as Methanobacterium and Methanosaeta were predominant, with Methanocorpusculum and Methanobrevibacter enriched at high OLRs. Electroactive bacteria, particularly Syntrophomonas, were enriched in R20-1 but decreased at high OLRs. Moreover, genes involved in both DIET and acetate decarboxylation pathways assigned to Methanosaeta showed increased expression with GAC addition. This research provides valuable insights into microbial evolution, functional gene changes and the correlation relationships among environmental factors and microorganisms with increasing OLR, offering a more cost-saving and efficient strategy for treating high-strength organic and acidic wastewater compared to traditional AD methods.