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1.
Two different MFC configurations designed for handling solid wastes as a feedstock were evaluated in batch mode: a single compartment combined membrane-electrodes (SCME) design; and a twin-compartment brush-type anode electrodes (TBE) design (reversed T-shape MFC with two-air cathode) without a proton exchange membrane (PEM). Cattle manure was tested as a model livestock organic solid waste feedstock. Under steady conditions, voltage of 0.38 V was recorded with an external resistance of 470 Ω. When digested anaerobic sludge was used as the seed in the SCME design, a maximum power density of 36.6 mW/m 2 was recorded. When hydrogen-generating bacteria (HGB) were used as the seed used in the TBE design, a higher power density of 67 mW/m 2 was recorded. 相似文献
2.
Food wastes were used as feedstock for the direct production of electricity in a microbial fuel cell (MFC). MFC operations
with volatile fatty acids (VFA) produced 533 mV with a maximum power density of 240 mW/m 2. Short-chain VFAs, such as acetate, were degraded more rapidly and thus supported higher power generation than longer chain
ones. In general, the co-existence of other, different VFAs slowed the removal of each VFA, which indicated that anodic microbes
were competing for different substrates. 16S rRNA gene analysis using PCR-DGGE indicated that the MFC operation with VFAs
had enriched unique microbial species. 相似文献
3.
The owners of farm-scale anaerobic digesters are relying on off-farm wastes or energy crops as a co-digestion feedstock with
animal manure in order to increase their production of methane and thus revenues. Switchgrass represents an interesting feedstock
for Canadian digesters owners as it is a high-yielding low-maintenance perennial crop, well adapted to northern climate. Methane
potential assays in batch tests showed methane production of 19.4 ± 3.6, 28.3 ± 1.7, 37.3 ± 7.1 and 45.7 ± 0.8 L kg −1, for raw manure, blended manure, manure and mulched switchgrass, manure and pretreated switchgrass, respectively. Two 6-L
lab-scale anaerobic digesters were operated for 130 days in order to assess the benefit of co-digesting switchgrass with bovine
manure (digester #2), at a 20% wet mass fraction, compared with a manure-only operation (digester #1) The digesters were operated
at an hydraulic retention time of 37 ± 6 days and at loads of 2.4 ± 0.6 and 2.6 ± 0.6 kg total volatile solids (TVS) L −1 day −1 for digesters #1 (D1) and #2 (D2), respectively. The TVS degradation reached 25 and 39%, which resulted in a methane production
of 1.18 ± 0.18 and 2.19 ± 0.31 L day −1 for D1 and D2, respectively. The addition of 20% on a wet mass ratio of switchgrass to a manure digester increased its methane
production by 86%. The co-digestion of switchgrass in a 500 m 3 manure digester could yield up to 10.2 GJ day −1 of purified methane or 1.1 MWh day −1 of electricity. 相似文献
4.
Using the anode effluent to compensate the alkalinization in a bio-cathode has recently been proposed as a way to operate
a microbial fuel cell (MFC) in a continuous and pH neutral way. In this research, we successfully demonstrated that the operation
of a MFC without any pH adjustments is possible by completing the liquid loop over cathode and anode. During the complete
loop operation, a stable current production of 23.2 ± 2.5 A m −3 MFC was obtained, even in the presence of 3.2–5.2 mg O 2 L −1 in the anode. The use of current collectors and subdivided electrical circuitries for relative large 2.5-L-scale MFCs resulted
in ohmic cell resistances in the order of 1.4–1.7 mΩ m 3 MFC, which were comparable to values of ten times smaller MFCs. Nevertheless, the bio-cathode activity still needs to be
improved significantly with a factor 10–50 in order achieve desirable current densities of 1,000 A m −3 MFC.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Sulfide and vanadium (V) are pollutants commonly found in wastewaters. A novel approach has been investigated using microbial
fuel cell (MFC) technologies by employing sulfide and V(V) as electron donor and acceptor, respectively. This results in oxidizing
sulfide and deoxidizing V(V) simultaneously. A series of operating parameters as initial concentration, conductivity, pH,
external resistance were carefully examined. The results showed that these factors greatly affected the performance of the
MFCs. The average removal rates of about 82.2 and 26.1% were achieved within 72 h operation for sulfide and V(V), respectively,
which were accompanied by the maximum power density of about 614.1 mW m −2 under all tested conditions. The products generated during MFC operation could be deposited, resulting in removing sulfide
and V(V) from wastewaters thoroughly. 相似文献
6.
Anaerobic bioenergy production processes including fermentative biohydrogen (BioH 2), anaerobic digestion (AD) and bioelectrochemical system have been investigated for converting municipal waste or various biomass feedstock to useful energy carriers. However, the performance of a microbial fuel cell (MFC) fed on the effluent from a two-stage biogas production process has not yet been investigated extensively in continuous reactor operation on complex substrates. In this study we have investigated the extent to which a microbial fuel cell (MFC) can reduce COD and recover further energy from the effluent of a two-stage biohydrogen and biomethane system. The performance of a four-module tubular MFC was determined at six different organic loadings (0.036–6.149 g sCOD L −1 d −1) in terms of power generation, COD removal efficiency, coulombic efficiency (CE) and energy conversion efficiency (ECE). A power density of 3.1 W m −3 was observed at the OLR = 0.572 g sCOD L −1 d −1, which resulted in the highest CE (60%) and ECE (0.8%), but the COD removal efficiency decreased at higher organic loading rates (35.1–4.4%). The energy recovery was 92.95 J L −1 and the energy conversion efficiency, based on total influent COD was found to be 0.48–0.81% at 0.572 g sCOD L −1 d −1. However, the energy recovery by the MFC is only reported for a four-module reactor and improved performance can be expected with an extended module count, as chemical energy remained available for further electrogenesis. 相似文献
7.
Different mixtures were digested in a single-stage, batch, mixed, laboratory scale mesophilic anaerobic digester at the Biomass Research Centre Laboratory (University of Perugia). The yield and the composition of biogas from the different substrates were evaluated and the cumulative curves were estimated. Two experimental campaigns were carried out, the first on three mixtures (chicken, pig and bovine manures), the second on animal and vegetal biomasses (chicken and cow manure, olive husk) with different inocula (rumen fluid and digested sludge). In the first campaign pig manure mixture showed the maximum biogas production (0.35 Nm 3/kg) and energy content (1.35 kWh/kg VS); in the second one the differences in produced biogas from the different inocula were analyzed: olive husk with piggery manure anaerobically digested as inoculum showed the higher biogas (0.28 Nm 3/kg VS) and methane yield (0.11 Nm 3/kg VS), corresponding to an energetic content of 1.07 kWh/kg VS. All data obtained from the laboratory scale anaerobic digester are comparable to the values in literature for several biomass and in particular for olive husk, dairy manure and chicken manure. 相似文献
8.
Electricity production and modeling of microbial fuel cell (MFC) from continuous beer brewery wastewater was studied in this paper. A single air-cathode MFC was constructed, carbon fiber was used as anode and diluted brewery wastewater (COD = 626.58 mg/L) as substrate. The MFC displayed an open-circuit voltage of 0.578 V and a maximum power density of 9.52 W/m 3 (264 mW/m 2). Using the model based on polarization curve, various voltage losses were quantified. At current density of 1.79 A/m 2, reaction kinetic loss and mass transport loss both achieved to 0.248 V; while ohmic loss was 0.046 V. Results demonstrated that it was feasible and stable for producing bioelectricity from brewery wastewater; while the most important factors which influenced the performance of the MFC are reaction kinetic loss and mass transport loss. 相似文献
9.
Scaling up microbial fuel cells (MFCs) requires the development of compact reactors with multiple electrodes. A scalable single
chamber MFC (130 mL), with multiple graphite fiber brush anodes and a single air-cathode cathode chamber (27 m 2/m 3), was designed with a separator electrode assembly (SEA) to minimize electrode spacing. The maximum voltage produced in fed-batch
operation was 0.65 V (1,000 Ω) with a textile separator, compared to only 0.18 V with a glass fiber separator due to short-circuiting
by anode bristles through this separator with the cathode. The maximum power density was 975 mW/m 2, with an overall chemical oxygen demand (COD) removal of >90% and a maximum coulombic efficiency (CE) of 53% (50 Ω resistor).
When the reactor was switched to continuous flow operation at a hydraulic retention time (HRT) of 8 h, the cell voltage was
0.21 ± 0.04 V, with a very high CE = 85%. Voltage was reduced to 0.13 ± 0.03 V at a longer HRT = 16 h due to a lower average
COD concentration, and the CE (80%) decreased slightly with increased oxygen intrusion into the reactor per amount of COD
removed. Total internal resistance was 33 Ω, with a solution resistance of 2 Ω. These results show that the SEA type MFC can
produce stable power and a high CE, making it useful for future continuous flow treatment using actual wastewaters. 相似文献
10.
Control of livestock diseases can become complicated when wild animals are involved. The Eurasian badger ( Meles meles) is considered the principle wildlife host of Mycobacterium bovis (which causes bovine tuberculosis, bTB) in Great Britain and Ireland, but wild deer have also been implicated. Whether wild
deer are likely to perpetuate bTB in cattle depends on the exposure risks they pose, the mode of pathogen transmission, the
distances over which the disease can be transported and whether they can maintain infection within their own populations independently
of other sources. We evaluated the likely host status of each of four species of wild British deer (red, roe, fallow and Reeves'
muntjac) and the badger across a range of densities typically observed in Britain by manipulating the reproductive number
equation proposed by Anderson and May ( 1991). We estimate that roe deer almost certainly act as spillover hosts at densities lower than 30 km −2, red deer below 16 km −2, muntjac below 6 km −2, fallow below 4 km −2 and the badger below 2 km −2. We also estimate that muntjac will almost certainly act as maintenance hosts at densities above 56 km −2, fallow above 47 km −2 and badgers above 24 km −2. For densities between these values, we cannot be certain of the host status of these species, and for red and roe deer we
cannot be certain of host status under most natural conditions typically experienced in parts of Britain experiencing high
incidence of bTB in cattle. However, enhanced transmission rates resulting from artificially high densities such as might
be experienced at supplementary feeding sites may be sufficient to promote independent maintenance of infection. We were not
able to confidently assign host status to any species over a wide range of densities, but conclude that this is likely to
reflect reality, where host status may be affected as much by, for example, demographic fluctuations as it is by population
density. Our results imply densities below which populations of wild deer inhabiting cattle bTB hotspots ought to be maintained
in order to control the possibility of them perpetuating the cycle of intra- and interspecific M. bovis transmission. 相似文献
11.
Algal biofuel production has gained a renewed interest in recent years but is still not economically feasible due to several
limitations related to algal culture. The objective of this study is to explore a novel attached culture system for growing
the alga Chlorella sp. as biodiesel feedstock, with dairy manure wastewater being used as growth medium. Among supporting materials tested for
algal attachment, polystyrene foam led to a firm attachment, high biomass yield (25.65 g/m 2, dry basis), and high fatty acid yield (2.31 g/m 2). The biomass attached on the supporting material surface was harvested by scraping; the residual colonies left on the surface
served as inoculum for regrowth. The algae regrowth on the colony-established surface resulted in a higher biomass yield than
that from the initial growth on fresh surface due to the downtime saved for initial algal attachment. The 10-day regrowth
culture resulted in a high biodiesel production potential with a fatty acid methyl esters yield of 2.59 g/m 2 and a productivity of 0.26 g/m −2 day −1. The attached algal culture also removed 61–79% total nitrogen and 62–93% total phosphorus from dairy manure wastewater,
depending on different culture conditions. The biomass harvested from the attached growth system (through scraping) had a
water content of 93.75%, similar to that harvested from suspended culture system (through centrifugation). Collectively, the
attached algal culture system with polystyrene foam as a supporting material demonstrated a good performance in terms of biomass
yield, biodiesel production potential, ease to harvest biomass, and physical robustness for reuse. 相似文献
12.
To reduce the amount of phosphate buffer currently used in Microbial Fuel Cell's (MFC's), we investigated the role of biological nitrification at the cathode in the absence of phosphate buffer. The addition of a nitrifying mixed consortia (NMC) to the cathode compartment and increasing ammonium concentration in the catholyte resulted in an increase of cell voltage from 0.3 V to 0.567 V (external resistance of 100 Ω) and a decrease of catholyte pH from 8.8 to 7.05. A large fraction of ammonium was oxidized to nitrite, as indicated by an increase of nitrate-nitrogen (NO 3−–N). An MFC inoculated with an NMC and supplied with 94.2 mgN/l ammonium to the catholyte could generate a maximum power of 2.1 ± 0.14 mW (10.94 ± 0.73 W/m 3). This compared favorably to an MFC supplied with either buffered or non-buffered solution. The buffer-free NMC inoculated cathodic chamber showed the smallest polarization resistance, suggesting that nitrification resulted in improved cathode performance. The improved performances of the phosphate buffer-free cathode and cell are positively related to biological nitrification, in which we suggest additional protons produced from ammonium oxidation facilitated electrochemical reduction of oxygen at cathode. 相似文献
13.
The impacts of feeding ratio and loading rate on the microbial community during co-digestion of grass silage with cow manure
in an anaerobic laboratory continuously stirred tank reactor were investigated by 16S rRNA gene-based fingerprints. The microbial
community remained stable when the reactor was fed with cow manure alone and with up to 20% of grass silage in feedstock at
an organic loading rate (OLR) of 2 kg VS m −3 day −1. Large changes in the bacterial community were observed when the loading ratio of grass was increased to 40%, while there
was little change in the archaeal community. During the increase in OLR from 2 to 4 kg VS m −3 day −1 the bacterial community structure showed few differences, whereas Archaea was undetectable. Sequencing of the major DGGE bands indicated that the phylum Bacteriodetes predominated in the bacterial community. Two unclassified bacteria with high abundance survived throughout the operation
of the reactor. 相似文献
14.
Single chambered mediatorless microbial fuel cell (MFC; non-catalyzed electrodes) was operated to evaluate the potential of bioelectricity generation from the treatment of composite waste vegetables (EWV) extract under anaerobic microenvironment using mixed consortia as anodic biocatalyst. The system was operated with designed synthetic wastewater (DSW; 0.98 kg COD/m 3-day) during adaptation phase and later shifted to EWV and operated at three substrate load conditions (2.08, 1.39 and 0.70 kg COD/m 3-day). Experimental data illustrated the feasibility of bioelectricity generation through the utilization of EWV as substrate in MFC. Higher power output (57.38 mW/m 2) was observed especially at lower substrate load. The performance of MFC was characterized based on the polarization behavior, cell potentials, cyclic voltammetric analysis and sustainable resistance. MFC operation also documented to stabilize the waste by effective removal of COD (62.86%), carbohydrates (79.84%) and turbidity (55.12%). 相似文献
15.
Varying chemical oxygen demand (COD) and sulphate concentrations in substrate were used to determine reaction kinetics and mass balance of organic matter and sulphate transformation in a microbial fuel cell (MFC). MFC with anodic chamber volume of 1 L, fed with wastewater having COD of 500 mg/L and sulphate of 200 mg/L, could harvest power of 54.4 mW/m2, at a Coulombic efficiency of 14%, with respective COD and sulphate removals of 90 and 95%. Sulphide concentration, even up to 1500 mg/L, did not inhibit anodic biochemical reactions, due to instantaneous abiotic oxidation to sulphur, at high inlet sulphate. Experiments on abiotic oxidation of sulphide to sulphur revealed maximum oxidation taking place at an anodic potential of −200 mV. More than 99% sulphate removal could be achieved in a MFC with inlet COD/sulphate of 0.75, giving around 1.33 kg/m3 day COD removal. Bioelectrochemical conversion of sulphate facilitating sulphur recovery in a MFC makes it an interesting pollution abatement technique. 相似文献
16.
The purpose of this study was to determine the effect of enrichment procedure on the performance and microbial diversity of
an air-cathode microbial fuel cell (MFC) which was explored for simultaneous azo dye decolorization and electricity generation.
Two different enrichment procedures in which glucose and Congo red were added into the MFCs sequentially (EP1) or simultaneously
(EP2) were tested by operating parallel MFCs independently for more than 6 months. The power density, electrode potential,
Congo red decolorization, biofilm morphology, and bacterial diversity of the MFCs under the two enrichment procedures were
compared and investigated. The results showed that the enrichment procedures have a negligible effect on the dye decolorization,
but significantly affected the electricity generation. More than 90% decolorization at dye concentration of 300 mg/L was achieved
within 170 h for the two tested enrichment procedures. However, the MFC with EP2 achieved a maximum power density of 192 mW/m 2, which was 75% higher than that of the MFC with EP1 (110 mW/m 2). The depressed surfaces of the bacteria in the MFC with EP1 indicated the allergic response caused by the subsequent addition
of Congo red. 16S rRNA sequencing analysis demonstrated a phylogenetic diversity in the communities of the anode biofilm and
showed clear differences between the anode-attached populations in the MFCs with a different enrichment procedure. This study
suggests that the enrichment procedure is important for the MFC explored for simultaneous dye decolorization and electricity
generation. 相似文献
17.
The cell voltage and degradation rate of p-nitrophenol (PNP) were monitored in a two-chambered microbial fuel cell (MFC) system. Degradation metabolites in the anode solution of MFC were analyzed by gas chromatography–mass spectrometry (GC–MS). PNP was used as substrate by the MFC that was inoculated with anaerobic sludge. The results showed that electricity output increased with the PNP concentration increased, the MFC displayed a maximum power density of 1.778 mW m −2 and a maximum PNP degradation rate of 64.69% when PNP was used as a sole substrate. However, the cell voltage and the PNP degradation rate with sodium acetate (402.3 mV and 95.96%) were higher than those fed with glucose (341.9 mV and 83.51%) when glucose and sodium acetate were used as a substrate, respectively. Furthermore, GC–MS analysis showed that the PNP was biodegraded completely after 142 h in the MFC. These results demonstrate that PNP can be used for electricity generation in MFC for practical applications of wastewater treatment. 相似文献
18.
As the microbial fuel cell (MFC) technology is getting nearer to practical applications such as wastewater treatment, it is
crucial to consider the different aspects that will make this technology viable in the future. In this paper, we provide information
about the specifications of an energy self-sufficient MFC system as a basis to extrapolate on the potential benefits and limits
of a future MFC-based wastewater treatment plant. We particularly emphasize on the importance of two crucial parameters that
characterize an MFC: its electromotive force ( E
emf) and its internal resistance ( R
int). A numerical projection using state-of-art values ( E
emf = 0.8 V and R
int = 5 Ω) emphasized on the difficulty at this moment to reach self-sufficiency using a reasonable number of MFCs at the laboratory
scale. We found that a realistic number of MFCs to provide enough voltage (=5 V) at a sufficient current (=0.8 A) to power
a pump requiring 4 W would be of 13 MFCs in series and 10 stacks of MFCs in parallel, resulting in a total number of 130 MFCs.
That would result in a treatment capacity of 144 L of domestic wastewater (0.5 g-COD L −1) per day. The total MFC system would be characterized by an internal resistance of 6.5 Ω. 相似文献
19.
Livestock manures are broadly used in agriculture to improve soil quality. However, manure application can increase the availability of organic carbon, thereby facilitating methane (CH 4) production. Cattle and swine manures are expected to have different CH 4 emission characteristics in rice paddy soil due to the inherent differences in composition as a result of contrasting diets and digestive physiology between the two livestock types. To compare the effect of ruminant and non-ruminant animal manure applications on CH 4 emissions and methanogenic archaeal diversity during rice cultivation (June to September, 2009), fresh cattle and swine manures were applied into experimental pots at 0, 20 and 40 Mg fresh weight (FW) ha −1 in a greenhouse. Applications of manures significantly enhanced total CH 4 emissions as compared to chemical fertilization, with cattle manure leading to higher emissions than swine manure. Total organic C contents in cattle (466 g kg −1) and swine (460 g kg −1) manures were of comparable results. Soil organic C (SOC) contents were also similar between the two manure treatments, but dissolved organic C (DOC) was significantly higher in cattle than swine manure. The mcrA gene copy numbers were significantly higher in cattle than swine manure. Diverse groups of methanogens which belong to Methanomicrobiaceae were detected only in cattle-manured but not in swine-manured soil. Methanogens were transferred from cattle manure to rice paddy soils through fresh excrement. In conclusion, cattle manure application can significantly increase CH 4 emissions in rice paddy soil during cultivation, and its pretreatment to suppress methanogenic activity without decreasing rice productivity should be considered. 相似文献
20.
In this work, two archaea microorganisms ( Haloferax volcanii and Natrialba magadii) used as biocatalyst at a microbial fuel cell (MFC) anode were evaluated. Both archaea are able to grow at high salt concentrations.
By increasing the media conductivity, the internal resistance was diminished, improving the MFC’s performance. Without any
added redox mediator, maximum power ( P
max) and current at P
max were 11.87/4.57/0.12 μW cm −2 and 49.67/22.03/0.59 μA cm −2 for H. volcanii, N. magadii and E. coli, respectively. When neutral red was used as the redox mediator, P
max was 50.98 and 5.39 μW cm −2 for H. volcanii and N. magadii, respectively. In this paper, an archaea MFC is described and compared with other MFC systems; the high salt concentration
assayed here, comparable with that used in Pt-catalyzed alkaline hydrogen fuel cells, will open new options when MFC scaling
up is the objective necessary for practical applications. 相似文献
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