Weihua He

Microbial electrochemical systems (MESs) present a promising approach for simultaneous water treatment and electricity generation. However, their performance is constrained by limited chemical-to-electrical energy conversion efficiency. Anode materials are central to this conversion process. Here, a self-supporting dual-precursor-derived carbon anode with excellent mechanical strength was developed by combining iron-rich biomass-derived heteroatom self-doping and pyrolytic pore formation with the intrinsic pore-forming ability and high carbon yield of phenolic resin. The resulting high-capacitance anode integrates hierarchically porous, heteroatom-doped carbon scaffolds with a mechanically robust matrix. The high capacitance generated by the synergistic effect of the porous architecture and endogenous Fe/N heteroatoms from the biomass precursor functions as both an electron repeaters and a capacitive buffer to support high biocurrent generation. Electrode materials derived from Enteromorpha sp. (E-MPR) exhibit a maximum capacitance of 1.67 ± 0.004 F cm–2 and supported a biomass loading of 1873.7 ± 74.1 μg cm–2, compared with 324.3 ± 12.1 μg cm–2 on carbon felt. The electroactive biofilm was dominated by Geobacter (81%). The functionally coupled electrode design optimizes the structure–performance relationships among the electrode material, the electroactive biofilm, and overall system efficiency. Consequently, a breakthrough in power and current densities was achieved, with values reaching 6138 ± 118 mW m–2 and 22 ± 1.2 A m–2, respectively. This work provides a notable enhancement in MES performance, suggesting that the high-performance anode is a promising candidate for engineering-scale applications of MES.

To improve the efficiency of AD for tetracycline-containing wastewater, this study systematically investigated the effects of ZVI and PAC on pollutant removal, VFA metabolism, biogas production, and sludge physicochemical characteristics. RSM was employed to optimize the co-dosing conditions of ZVI and PAC. The results suggested that ZVI and PAC could significantly facilitate COD degradation, and the optimal dosages for COD removal were 1000 mg/L ZVI and 2000 mg/L PAC with a removal efficiency of 61.03% and 56.9%, respectively. Both additives effectively accelerated the catabolism of typical VFAs, thereby mitigating the accumulation of intermediate metabolites that may cause AD system instability. In terms of biogas production, 1000 mg/L ZVI and 2000 mg/L PAC enhanced methane yield by 55.9% and 35.0% compared to the control group, with ZVI exhibiting a more prominent enhancement effect. Mechanistic analysis suggested that ZVI and PAC reinforced the AD process through multiple pathways: enhancing the electrical conductivity of the AD system, possibly facilitating the electron transfer pathways, and stimulating the secretion of EPSs by anaerobic microbes. RSM optimization yielded the optimal co-dosing parameters: 1000 mg/L ZVI and 1200 mg/L PAC. Under these conditions, the methane yield was increased by 71.18% relative to the control group, and the model validation accuracy reached 97.94%. This study provides a viable technical strategy and theoretical basis for enhancing the efficiency of anaerobic treatment of tetracycline-containing wastewater.

Microbial electrochemical cells (MxCs) offer a sustainable approach for wastewater treatment and energy recovery by harnessing the electroactive properties of microorganisms. This study explores the enrichment of Geobacter species on anode biofilms in single-(S-MxCs) and double-chambered (D-MxCs) MxCs, using domestic wastewater without an external anode potential. Stable current densities were achieved within 10 days for S-MxCs (9.52 ± 0.8 A/m²) and 14 days for D-MxCs (4.28 ± 0.9 A/m²), with S-MxCs showing a superior electrochemical performance. Hydrogen production rates were higher in D-MxCs (14.93 ± 0.66 mmol H₂/L/day) compared to S-MxCs (9.46 ± 0.8 mmol H₂/L/day), with cumulative production rates of 12.9 ± 1.3 mmol H₂/g COD and 6.48 ± 1.4 mmol H₂/g COD, respectively. Cyclic voltammetry confirmed enhanced bioelectrocatalytic activity in S-MxCs, while SEM imaging showed denser biofilms on S-MxC anodes. The novelty of this study lies in its demonstration of efficient biofilm development and microbial community resilience under non-potentialized conditions, providing insights that advance the practical application of MxCs in environmental biotechnology.

This study attempts to overcome the challenges associated with the degradation of complex organic substances like corn straw hydrolysate in hydrogen recovery by strategically enriching functional microbial communities in single-chamber cubic microbial electrolysis cells (MECs). We applied negative pressure, using acetate or xylose as electron donors, to mitigate the hydrogen sink issues caused by methanogens. This innovative method significantly enhanced MEC performance. MECs enriched with xylose demonstrated superior performance, achieving a hydrogen production rate 3.5 times higher than that achieved by those enriched with acetate. Under negative pressure, hydrogen production in N-XyHy10 reached 0.912 ± 0.08 LH₂/L MEC/D, which was 6.7 times higher than in the passive-pressure MECs (XyHy10). This advancement also resulted in substantial increases in current density (73%), energy efficiency (800%), and overall energy efficiency (540%) compared with MECs operated under passive pressure with 10% hydrolysate feed. The enrichment of polysaccharide-degrading bacteria such as Citrobacter and Pseudomonas under negative pressure underscores the potential for their industrial application in harnessing complex organic substrates for bioenergy production in single-chamber MECs. This is a promising approach to scaling up bioenergy recovery processes. The findings of this research study contribute significantly to the field by demonstrating the efficacy of negative pressure in enhancing microbial activity and energy recovery, thereby offering a promising strategy for improving bioenergy production efficiency in industries.

A stable aerobic consortium was enriched to degrade crystalline cellulose (Whatman filter paper 1). The degradation efficiency of the consortium after 7 days of incubation was 91% compared to the control. One bacterial isolate, C7, capable of degrading various cellulosic substrates, was obtained from the consortium under aerobic conditions. The sequencing of 16s rDNA revealed that it was related to Paenibacillus sp. It degraded 83% of cotton after 3 days of incubation. The degradation efficiency of Paenibacillus sp. C7 for filter paper, cotton, and avicel was 90%, 90%, and 92% after 5 days of incubation compared to the control. It also degraded non-pretreated agricultural residues efficiently by 70% for rice straw and 46% for wheat bran in 10 days. Scanning electron micrographs (SEMs) of degraded filter paper after 2 days of incubation indicated smoother and thinner fabrics in its structure. It is a potential cheaper candidate for the degradation of lignocellulosic biomass without any pretreatment.

To date, dozens of pilot-scale microbial fuel cell (MFC) devices have been successfully developed worldwide for treating various types of wastewater. The availability and configurations of separators are determining factors for the economic feasibility, efficiency, sustainability, and operability of these devices. Thus, the concomitant advances between the separators and pilot-scale MFC configurations deserve further clarification. The analysis of separator configurations has shown that their evolution proceeds as follows: from ion-selective to ion-non-selective, from nonpermeable to permeable, and from abiotic to biotic. Meanwhile, their cost is decreasing and their availability is increasing. Notably, the novel MFCs configured with biotic separators are superior to those configured with abiotic separators in terms of wastewater treatment efficiency and capital cost. Herein, a highly comprehensive review of pilot-scale MFCs (>100 L) has been conducted, and we conclude that the intensive stack of the liquid cathode configuration is more advantageous when wastewater treatment is the highest priority. The use of permeable biotic separators ensures hydrodynamic continuity within the MFCs and simplifies reactor configuration and operation. In addition, a systemic comparison is conducted between pilot-scale MFC devices and conventional decentralized wastewater treatment processes. MFCs showed comparable cost, higher efficiency, long-term stability, and significant superiority in carbon emission reduction. The development of separators has greatly contributed to the availability and usability of MFCs, which will play an important role in various wastewater treatment scenarios in the future.