Caixing Tian

Simultaneous microbial and electrochemical reductions of vanadium (V) with bioelectricity generation in microbial fuel cells

Simultaneous microbial and electrochemical reductions of vanadium (V) with bioelectricity generation were realized in microbial fuel cells (MFCs). With initial V(V) concentrations of 75 mg/l and 150 mg/l in anolyte and catholyte, respectively, stable power output of 419±11 mW/m(2) was achieved. After 12h operation, V(V) concentration in the catholyte decreased to the value similar to that of the initial one in the anolyte, meanwhile it was nearly reduced completely in the anolyte. V(IV) was the main reduction product, which subsequently precipitated, acquiring total vanadium removal efficiencies of 76.8±2.9%. Microbial community analysis revealed the emergence of the new species of Deltaproteobacteria and Bacteroidetes as well as the enhanced Spirochaetes mainly functioned in the anode. This study opens new pathways to successful remediation of vanadium contamination.

Simultaneous sulfide removal and electricity generation with corn stover biomass as co-substrate in microbial fuel cells

Microbial fuel cells (MFCs), representing a promising method to treat combined pollutants with energy recovery, were utilized to remove sulfide and recover power with corn stover filtrate (CSF) as the co-substrate in present study. A maximum power density of 744 mW/m(2) was achieved with sulfide removal of 91% during 72 h operation when the CSF concentrations (mg-COD/l) and the electrolyte conductivity were set at 800 mg/l and 10.06 mS/cm, respectively, while almost 52% COD was removed due to the microbial degradation of CSF to the volatile organic carbons. CSF concentrations and electrolyte conductivities had significant effects on the performance of the MFCs. Simultaneous removals of inorganic pollutant and complex organic compounds with electricity generation in MFCs are reported for the first time. These results provide a good reference for multiple contaminations treatment especially sulfide containing wastewaters based on the MFC technology.

Microbial reduction and precipitation of vanadium (V) in groundwater by immobilized mixed anaerobic culture

Vanadium is an important contaminant impacted by natural and industrial activities. Vanadium (V) reduction efficiency as high as 87.0% was achieved by employing immobilized mixed anaerobic sludge as inoculated seed within 12h operation, while V(IV) was the main reduction product which precipitated instantly. Increasing initial V(V) concentration resulted in the decrease of V(V) removal efficiency, while this index increased first and then decreased with the increase of initial COD concentration, pH and conductivity. High-throughput 16S rRNA gene pyrosequencing analysis indicated the decreased microbial diversity. V(V) reduction was realized through dissimilatory reduction process by significantly enhanced Lactococcus and Enterobacter with oxidation of lactic and acetic acids from fermentative microorganisms such as the enriched Paludibacter and the newly appeared Acetobacterium, Oscillibacter. This study is helpful to detect new functional species for V(V) reduction and constitutes a step ahead in developing in situ bioremediations of vanadium contamination.

Continuous electricity generation with piggery wastewater treatment using an anaerobic baffled stacking microbial fuel cell

AbstractAnaerobic baffled stacking microbial fuel cells (ABSMFCs) consisting of four individual MFCs with total volume of 6.4 L was constructed to generate electricity from piggery wastewater in present study. Anode materials (carbon paper, carbon fiber felt, and graphite granule) and anode connecting modes of the four MFCs (in series or parallel) could affect the bioelectricity generation and wastewater treatment effects. When they were connected in series, voltage loss occurred and voltage reversed with increase in current between some MFCs. The influent COD loadings showed significant relationship to the performance of ABSMFC, as it increased from 0.2 to 4.0 g/L d, voltage output across an external resistance of 1,000 Ω decreased by 71.7% (in series) and 30.7% (in parallel), respectively; coulombic efficiency decreased rapidly by 96.7% (in series) and 94.3% (in parallel), while COD removal efficiency initially increased and then decreased. This study demonstrated that the large volume ABSMFC can realiz...

Optimization of enhanced bioelectrical reactor with electricity from microbial fuel cells for groundwater nitrate removal

ABSTRACT Factors influencing the performance of a continual-flow bioelectrical reactor (BER) intensified by microbial fuel cells for groundwater nitrate removal, including nitrate load, carbon source and hydraulic retention time (HRT), were investigated and optimized by response surface methodology (RSM). With the target of maximum nitrate removal and minimum intermediates accumulation, nitrate load (for nitrogen) of 60.70 mg/L, chemical oxygen demand (COD) of 849.55 mg/L and HRT of 3.92 h for the BER were performed. COD was the dominant factor influencing performance of the system. Experimental results indicated the undistorted simulation and reliable optimized values. These demonstrate that RSM is an effective method to evaluate and optimize the nitrate-reducing performance of the present system and can guide mathematical models development to further promote its practical applications.

Characteristics of ultra-fine bubble water and its trials on enhanced methane production from waste activated sludge

In this study biogas production efficiency was evaluated by adding ultra-fine bubble water (UFBW) into waste activated sludge (WAS) through anaerobic digestion (AD). Four kinds of gases, i.e. Air, N2, CO2 and H2 were introduced into tap water (TW) to prepare the UFBW with their properties being first investigated. Results show that hundreds of millions of nanoscale bubbles with the negative zeta potential could be stable in the UFBW for longer than two weeks whereas almost no nanometer bubbles could be detected in the raw TW. As for their impact on subsequent AD of WAS, the cumulative methane production with the addition of UFBW was 14-21% higher than that from the raw TW addition group. Interestingly, the Air-UFBW also could promote the biogas production in this study, which is different from the common understanding of AD, an obligate anaerobic process.