Tannic acid (TA), a common industrial contaminant in sectors such as papermaking and leather production, affects the anaerobic treatment of wastewater by forming complexes with proteins in sludge granules, thereby inhibiting microbial efficiency and promoting sludge deflocculation. Although techniques such as intermittent electricity can promote microbial growth, they do not effectively resolve sludge deflocculation. Additionally, although biochar (BC) enhances the abundance of microbes, it does not significantly improve microbial activity or treatment performance. This study aimed to alleviate the adverse effects of TA on anaerobic granular sludge (AnGS) by synergistically applying intermittent electrical stimulation and BC. Co-treatment with 1 h-on/off intermittent electricity and 3 g/L BC notably reduced granular sludge deflocculation. Consequently, the chemical oxygen demand (COD) removal efficiency in wastewater reached 91.73 %, with a maximum methane production per cycle of 230.59 mL/g COD, 16.95 % higher than that of the control reactor (197.17 mL/g COD). This improvement was attributed to the synergistic action of intermittent electricity and BC, which enriched the functional microorganisms and stimulated their activity, thereby facilitating direct interspecies electron transfer. Additionally, enhancing the polysaccharide and protein levels in extracellular polymeric substances improved the stability of granular sludge, ultimately mitigating the adverse effects of TA on AnGS.

The introduction of high-calcium wastewater into anaerobic reactors can lead to severe calcification of anaerobic granular sludge, compromising sludge activity and potentially causing system failure. This study explores the application of urea-hydrolyzing Bacillus pasteurii to facilitate microbially induced calcite precipitation (MICP) as an innovative pretreatment strategy for high-calcium wastewater. The aim is to achieve decalcification, mitigate granular sludge calcification, and enhance sludge performance. The approach was validated using simulated high-calcium wastewater from the papermaking industry, with optimal conditions achieving a calcium ion removal rate of 98.29 %. This significantly reduced the detrimental impact of high calcium concentrations on sludge activity, delayed the calcification process, and improved the biochemical performance of anaerobic granular sludge, with methanogenic activity increasing by 60.79 %. The enhanced performance can be attributed to the ammonia produced from the urease-catalyzed hydrolysis of urea, which supplemented nitrogen availability for anaerobic digestion, resulting in an optimized carbon-to-nitrogen ratio aligned with practical treatment conditions. This study offers a novel decalcification strategy for high-calcium wastewater, providing a promising solution to the challenges associated with anaerobic granular sludge calcification.

In this study, exogenous N-acyl-homoserine lactones (AHLs) was added to resist the stress by high concentration (0.5 g/L) of urea formaldehyde resin microplastics (UF-MPs) on anaerobic granular sludge (AnGS), aiming to provide a viable strategy for AnGS to withstand elevated levels of UF-MPs toxicity elucidate the intricate regulatory mechanism of AHL-mediated AnGS-QS regulation. The results showed that the three different signaling molecules (C4-HSL, C6-HSL, and C8-HSL) improved the performance of AnGS under high concentration (0.5 g/L) urea-formaldehyde resin stress, and increased sludge COD removal (4.48%, 4.76%, and 3.35%, respectively) and methanogenic activity (8.38%, 1.92%, and 18.76%, respectively). The addition of C4-HSL has the best effect on sludge particle size and strength, which is attributed to the fact that C4-HSL can significantly increase the content of polysaccharides and proteins in tightly bound extracellular polymeric substances (TB-EPS) (27.1% and 27.1%, respectively). C8-HSL most obviously promotes energy metabolism and EPS biosynthesis gene expression. Metagenomic analysis showed that trace AHLs could promote the abundance of enzymes and functional genes related to the main pathway of methane metabolism, increase the relative abundance of Methanothrix of acetophilic methanogens from 27.79% in the control group to 27.85% (C4-HSL), 28.90% (64-HSL), and 30.03% (C8-HSL), thereby improving community stability.

In this paper, transitional bimetallic catalysts (FeS2/MoS2) were prepared by a simple one-step hydrothermal method, which were directly applied to MFC anodes for the treatment of high-concentration wastewater with simultaneous biopower generation. The obtained catalysts were highly biocompatible and favorable for inducing the enrichment of electroactive microorganisms and shortening the initiation cycle. The maximum power density (Pmax) and current density of the obtained anode reached 2.87 W center dot m(-2) and 4.37 A center dot m(-2) under 4000 mg center dot L-1 influent, which were 171% and 65% higher than that of bare carbon cloth, respectively. The chemical oxygen demand (COD) removal rate reached 98.82%. 16 S rRNA gene sequence analysis showed that the main electrophilic microorganisms induced by FeS2/8%MoS2-modified anodes were Synergistota (30.94%) and Geoalkallbacter (15.93%) compared to CC anodes. The resulting anode possesses excellent redox activity and high biocompatibility, and is simple and inexpensive to prepare. More importantly, it accelerated the extracellular electron transfer rate at the interface between the electroactive bacteria and the anode, providing a new idea of choice for single-chamber microbial fuel cells for low-cost treatment of high-concentration wastewater.