A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performanc...A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions （in complete darkness and presence of light）, and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30 h. Changes in chemical oxygen demand, and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness （D-MFC） with a stable open circuit voltage of 700 mV, presence of light led to growth of other species, and consecutively low and unsteady open circuit voltage. Although the performance of the MFC subjected to light （L-MFC） was quite low and unsteady in dynamic state （internal resistance = 100 Ω, power density = 5.15 W.m-3）. it reached power density of 9.2 W.m-3 which was close to performance of D-MFC （internal resistance = 50 d, power density = 10.3 W.m-3）. Evaluated only for D-MFC, the coulombic efficiency observed in batch mode （30%） was quite higher than the maximum acquired in continuous mode （9.6%） even at the highest hydraulic retention time. In this study, changes in phosphate and different types of nitrogen existing in dairy wastewater were investigated for the first time. At hydraulic retention time of 8 h, the orthophosphate concentration in effluent was 84% higher compared to influent. Total nitrogen and total Kjeldahl nitrogen were reduced 70% and 99% respectively at hydraulic retention time of 30 h, while nitrate and nitrite concentrations increased. The microbial electrolysis cell （MEC）, revamped from D-MEC, showed the maximum gas production of 0.2 m3 H2·m-3·d-1 at 700 mV applied voltage.展开更多
A fungal consortium including Aspergillus niger, Mucor hiemalis and Galactomyces geotrichum was tested for the treatment of dairy wastewater. The bio-augmentation method was tested at lab-scale （4 L）, at pilot scale...A fungal consortium including Aspergillus niger, Mucor hiemalis and Galactomyces geotrichum was tested for the treatment of dairy wastewater. The bio-augmentation method was tested at lab-scale （4 L）, at pilot scale （110 L） and at an industrial scale in Wastewater Treatment Plants （WWTP）. The positive impact of fungal addition was confirmed when fungi was beforehand accelerated by pre-culture on whey （5 g/L lactose） or on the dairy effluent. Indeed, chemical oxygen demand （COD） removal yields increased from 55% to 75% for model medium, diluted milk. While after inoculation of an industrial biological tank from a dairy factory with the fungal consortium accelerated by pre-cultivation in a 1000 L pilot plant, the outlet COD values decreased from values above the standard one （100 mg/L） to values in the range of 50-70 mg/L. In addition, there was a clear impact of fungal addition on the ＇hard＇ or non-biodegradable COD owing to the significant reduction of the increase of the COD on BOD 5 ratio between the inlet and the outlet of the biological tank of WWTP. It was in the range of 451%-1111% before adding fungal consortium, and in the range of 257%-153% after bio-augmentation with fungi. An inoculated bioreactor with fungal consortium was developed at lab-scale and demonstrated successfully at pilot scale in WWTP.展开更多
A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a...A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments（activated sludge） in the 6th segment and sending the sediments beck to the 1st and 2nd segments.Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter（biological oxygen demand [BOD]）, and dissolved oxygen（DO） content. Microbiota from five segments（1st and four successive aerobic segments） in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions（such as DO）, suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.展开更多
基金supported by Sharif University of Technology,Vice President for Research Grant G930111
文摘A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions （in complete darkness and presence of light）, and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30 h. Changes in chemical oxygen demand, and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness （D-MFC） with a stable open circuit voltage of 700 mV, presence of light led to growth of other species, and consecutively low and unsteady open circuit voltage. Although the performance of the MFC subjected to light （L-MFC） was quite low and unsteady in dynamic state （internal resistance = 100 Ω, power density = 5.15 W.m-3）. it reached power density of 9.2 W.m-3 which was close to performance of D-MFC （internal resistance = 50 d, power density = 10.3 W.m-3）. Evaluated only for D-MFC, the coulombic efficiency observed in batch mode （30%） was quite higher than the maximum acquired in continuous mode （9.6%） even at the highest hydraulic retention time. In this study, changes in phosphate and different types of nitrogen existing in dairy wastewater were investigated for the first time. At hydraulic retention time of 8 h, the orthophosphate concentration in effluent was 84% higher compared to influent. Total nitrogen and total Kjeldahl nitrogen were reduced 70% and 99% respectively at hydraulic retention time of 30 h, while nitrate and nitrite concentrations increased. The microbial electrolysis cell （MEC）, revamped from D-MEC, showed the maximum gas production of 0.2 m3 H2·m-3·d-1 at 700 mV applied voltage.
文摘A fungal consortium including Aspergillus niger, Mucor hiemalis and Galactomyces geotrichum was tested for the treatment of dairy wastewater. The bio-augmentation method was tested at lab-scale （4 L）, at pilot scale （110 L） and at an industrial scale in Wastewater Treatment Plants （WWTP）. The positive impact of fungal addition was confirmed when fungi was beforehand accelerated by pre-culture on whey （5 g/L lactose） or on the dairy effluent. Indeed, chemical oxygen demand （COD） removal yields increased from 55% to 75% for model medium, diluted milk. While after inoculation of an industrial biological tank from a dairy factory with the fungal consortium accelerated by pre-cultivation in a 1000 L pilot plant, the outlet COD values decreased from values above the standard one （100 mg/L） to values in the range of 50-70 mg/L. In addition, there was a clear impact of fungal addition on the ＇hard＇ or non-biodegradable COD owing to the significant reduction of the increase of the COD on BOD 5 ratio between the inlet and the outlet of the biological tank of WWTP. It was in the range of 451%-1111% before adding fungal consortium, and in the range of 257%-153% after bio-augmentation with fungi. An inoculated bioreactor with fungal consortium was developed at lab-scale and demonstrated successfully at pilot scale in WWTP.
基金supported by a grant for the promotion of desterilizing regional resources funded by the Hokkaido Bureau of Economy,Trade and Industry
文摘A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments（activated sludge） in the 6th segment and sending the sediments beck to the 1st and 2nd segments.Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter（biological oxygen demand [BOD]）, and dissolved oxygen（DO） content. Microbiota from five segments（1st and four successive aerobic segments） in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions（such as DO）, suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.
