The influence of flue gas sparging (7% CO(2)) on the performance of two 465 L High-Rate Algal Pon... more The influence of flue gas sparging (7% CO(2)) on the performance of two 465 L High-Rate Algal Ponds (HRAPs) treating diluted swine manure at 10 days of hydraulic retention time was evaluated under continental climatic conditions (Castilla y León, Spain). COD, NH(4)(+), and PO(4)(3-) removal efficiencies were not significantly affected by flue gas input (at 2.2 and 5.5 L min(-1)), which suggests that CO(2) sparging does not compromise wastewater treatment in HRAPs. In this particular study, COD and NH(4)(+) removal efficiencies of 56+/-31% (near to maximum swine manure biodegradability) and 98+/-1%, respectively, were consistently maintained, regardless of the environmental and operational conditions. CO(2) sparging resulted however in lower pH values (approximately 2 units lower) and an enhanced NH(4)(+) nitrification (higher NO(3)(-) and NO(2)(-) concentrations) compared to the system operated in the absence of flue gas supply. Biomass concentration was only higher (approximately 30% than in the control HRAP) when flue gases were supplied at 5.5 L min(-1), probably due to the fact that the higher irradiances and temperatures prevailing within this experimental period resulted in an inorganic carbon-limited scenario in the control HRAP. Therefore, it can be concluded that CO(2) assimilation would be ultimately dependent on the occurrence of inorganic carbon limitation and will never occur in light, COD or nutrients-limited scenarios.
"Two green microalgae (Scenedesmus obliquus and Chlorella sorokiniana), one cyanobacterium (Spiru... more "Two green microalgae (Scenedesmus obliquus and Chlorella sorokiniana), one cyanobacterium (Spirulina
platensis), one euglenophyt (Euglena viridis) and two microalgae consortia were evaluated for their ability
to support carbon, nitrogen and phosphorous removal in symbiosis with activated sludge bacteria during
the biodegradation of four and eight times diluted piggery wastewater in batch tests. C. sorokiniana and E.
viridis were capable of supporting the biodegradation of four and eight times diluted wastewater. On the
other hand, while S. obliquus and the consortia isolated from a swine manure stabilization pond were only
able to grow in eight times diluted wastewater, S. platensis and the consortium isolated from a high rate
algal pond treating swine manure were totally inhibited regardless of the dilution applied. TOC removal
efficiencies (RE) ranging from 42% to 55% and NH4
+-RE from 21% to 39% were recorded in the tests exhibiting
photosynthetic oxygenation. The similar oxygen production rates exhibited by the tested microalgae
under autotrophic conditions (from 116 to 133 mg O2 Lÿ1 dÿ1) suggested that factors other than the photosynthetic
oxygenation potential governed piggery wastewater biodegradation. Microalgal tolerance
towards NH3 was hypothesized as the key selection criterion. Further studies in a continuous algal–bacterial
photobioreactor inoculated with C. sorokiniana, S. obliquus and S. platensis showed that C. sorokiniana,
the species showing the highest NH3-tolerance, rapidly outcompeted the rest of the microalgae
during the biodegradation of eight times diluted wastewater, achieving TOC and NH4
+-RE comparable
to those recorded in the batch biodegradation tests."
During a biological survey carried out in 2009, epiphytic and phytoplanktonic diatom assemblages ... more During a biological survey carried out in 2009, epiphytic and phytoplanktonic diatom assemblages of three shallow saline lakes in the South of the Bolivian Altiplano (Lipez Area) (>4100 m asl), were studied. Within the identified taxa, Navicula pseudogracilis, Staurophora vilamae, Halamphora atacamana, Halamphora carvajaliana, Halamphora atacamae, Denticula valida f. major and Surirella chilensis were studied in detail. For each of these, a brief morphologic and morphometric description, a collection of bibliographic references where the taxon is cited or illustrated in the scientific literature, and light and scanning electronic microscopy images are presented. S. vilamae and D. valida f. major are cited for the first time out of their type localities, this last taxa observed for the first time in the world since 1894. Besides, N. pseudogracilis is cited as a new species for Bolivia and the ultrastructure of this taxon and D. valida f. major were illustrated for the first time.
The performance of two 464-L high rate algal ponds (HRAPs) treating 20- and 10-folds diluted swin... more The performance of two 464-L high rate algal ponds (HRAPs) treating 20- and 10-folds diluted swine manure at 10 days of hydraulic residence time was evaluated under continental climatic conditions in Castilla y Leon (Spain) from January to October. Under optimum environmental conditions (from July to September), both HRAPs supported a stable and efficient carbon and nitrogen oxidation performance, with average COD and TKN removal efficiencies of 76 ± 11% and 88 ± 6%, respectively, and biomass productivities ranging from 21 to 28 g/m2 d. Nitrification was identified as the main TKN removal mechanism at dissolved oxygen concentrations higher than 2 mg/L (accounting for 80–86% of the TKN removed from January to May and for 54% from July to September). On the other hand, empirical evidences of a simultaneous nitrification–denitrification process were found at dissolved oxygen concentrations lower than 0.5 mg/L (high organic loading rates). However, despite the achievement of excellent COD and nitrogen oxidation performance, phosphorous removal efficiencies lower than 10% were recorded in both HRAPs probably due to the high buffer capacity of the piggery wastewater treated (absence of abiotic pH-mediated View the MathML source precipitation). Finally, a detailed monitorization of the dynamics of microalgae population revealed that the combination of moderate temperatures/solar irradiances and high organic loading rates, prevailing during late spring and summer, supported higher microalgae diversities than those found during winter conditions.
Coagulation-flocculation followed by a static decanter (StD) or a dissolved air flotation system ... more Coagulation-flocculation followed by a static decanter (StD) or a dissolved air flotation system (DAFAST) can reduce highly the energetic and production cost of treating urban wastewater in a high rate algal ponds (HRAP). Undesired Flotation or auto-flotation phenomenon took place during the operation of StD, even at very favourable settling conditions, therefore StD seem to be not very promising as method of microalgae pre-concentration. On the other hand, DAFAST operated under the addition of 20 ppm of coagulant and 5 ppm of cationic flocculant provided and effluent that fits the most restrictive limits of discharge (91/271/EC), averaging 20pmmTSS and 70 ppm COD, and reaching a concentration factor almost of 100.
With the hypothesis that light supply can impact the removal of veterinary antibiotics during liv... more With the hypothesis that light supply can impact the removal of veterinary antibiotics during livestock wastewater treatment in high rate algal ponds (HRAPs), this study was undertaken to determine the mechanisms of tetracycline removal in these systems. For this purpose, two HRAPs were fed with synthetic wastewater for 46 days before tetracycline was added at 2 mg L(-1) to the influent of one of the reactors (Te-HRAP). From day 62, dissolved tetracycline removal stabilized around 69 ± 1% in the Te-HRAP and evidence from batch assays suggests that this removal was mainly caused by photodegradation and biosorption. Tetracycline addition was followed by the deflocculation of the Te-HRAP biomass but had otherwise no apparent impact on the removal of the chemical oxygen demand (COD) and biomass productivity. The results from the batch assays also suggested that the light-shading and/or pollutant-sequestrating effects of the biomass limited tetracycline removal in the pond. For the first time, these results demonstrate that the shallow geometry of HRAPs is advantageous to support the photodegradation of antibiotics during wastewater biological treatment but that the presence of these pollutants could hamper biomass recovery. These findings have significant implications for algal-based environmental biotechnologies and must be confirmed under field conditions.
During a biological survey carried out in five shallow, high-altitude saline lakes of the Bolivia... more During a biological survey carried out in five shallow, high-altitude saline lakes of the Bolivian Altiplano in 2009, six unknown diatom
taxa were found in various lake populations. Detailed light and scanning electron microscopy observations allowed the description of the
following new taxa: Navicula venetoides (distinguished from N. veneta Kützing by having coarser lineate striae), Pinnularia boliviana
(similar to P. rhombarea var. halophila Krammer but with coarser striae and a narrower central area), Nitzschia sansimoni (morphologically
close to N. supralitorea Lange-Bertalot, the latter having denser striae), Surirella striatula var. halophila (differing from the nominate and
other varieties in a distinctly heteropolar outline and the presence of denser fibulae) and S. moralesii (with large, strictly isopolar valves
and a deep pervalvar depression). Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical
implications of these findings, are briefly discussed.
The influence of flue gas sparging (7% CO(2)) on the performance of two 465 L High-Rate Algal Pon... more The influence of flue gas sparging (7% CO(2)) on the performance of two 465 L High-Rate Algal Ponds (HRAPs) treating diluted swine manure at 10 days of hydraulic retention time was evaluated under continental climatic conditions (Castilla y León, Spain). COD, NH(4)(+), and PO(4)(3-) removal efficiencies were not significantly affected by flue gas input (at 2.2 and 5.5 L min(-1)), which suggests that CO(2) sparging does not compromise wastewater treatment in HRAPs. In this particular study, COD and NH(4)(+) removal efficiencies of 56+/-31% (near to maximum swine manure biodegradability) and 98+/-1%, respectively, were consistently maintained, regardless of the environmental and operational conditions. CO(2) sparging resulted however in lower pH values (approximately 2 units lower) and an enhanced NH(4)(+) nitrification (higher NO(3)(-) and NO(2)(-) concentrations) compared to the system operated in the absence of flue gas supply. Biomass concentration was only higher (approximately 30% than in the control HRAP) when flue gases were supplied at 5.5 L min(-1), probably due to the fact that the higher irradiances and temperatures prevailing within this experimental period resulted in an inorganic carbon-limited scenario in the control HRAP. Therefore, it can be concluded that CO(2) assimilation would be ultimately dependent on the occurrence of inorganic carbon limitation and will never occur in light, COD or nutrients-limited scenarios.
"Two green microalgae (Scenedesmus obliquus and Chlorella sorokiniana), one cyanobacterium (Spiru... more "Two green microalgae (Scenedesmus obliquus and Chlorella sorokiniana), one cyanobacterium (Spirulina
platensis), one euglenophyt (Euglena viridis) and two microalgae consortia were evaluated for their ability
to support carbon, nitrogen and phosphorous removal in symbiosis with activated sludge bacteria during
the biodegradation of four and eight times diluted piggery wastewater in batch tests. C. sorokiniana and E.
viridis were capable of supporting the biodegradation of four and eight times diluted wastewater. On the
other hand, while S. obliquus and the consortia isolated from a swine manure stabilization pond were only
able to grow in eight times diluted wastewater, S. platensis and the consortium isolated from a high rate
algal pond treating swine manure were totally inhibited regardless of the dilution applied. TOC removal
efficiencies (RE) ranging from 42% to 55% and NH4
+-RE from 21% to 39% were recorded in the tests exhibiting
photosynthetic oxygenation. The similar oxygen production rates exhibited by the tested microalgae
under autotrophic conditions (from 116 to 133 mg O2 Lÿ1 dÿ1) suggested that factors other than the photosynthetic
oxygenation potential governed piggery wastewater biodegradation. Microalgal tolerance
towards NH3 was hypothesized as the key selection criterion. Further studies in a continuous algal–bacterial
photobioreactor inoculated with C. sorokiniana, S. obliquus and S. platensis showed that C. sorokiniana,
the species showing the highest NH3-tolerance, rapidly outcompeted the rest of the microalgae
during the biodegradation of eight times diluted wastewater, achieving TOC and NH4
+-RE comparable
to those recorded in the batch biodegradation tests."
During a biological survey carried out in 2009, epiphytic and phytoplanktonic diatom assemblages ... more During a biological survey carried out in 2009, epiphytic and phytoplanktonic diatom assemblages of three shallow saline lakes in the South of the Bolivian Altiplano (Lipez Area) (>4100 m asl), were studied. Within the identified taxa, Navicula pseudogracilis, Staurophora vilamae, Halamphora atacamana, Halamphora carvajaliana, Halamphora atacamae, Denticula valida f. major and Surirella chilensis were studied in detail. For each of these, a brief morphologic and morphometric description, a collection of bibliographic references where the taxon is cited or illustrated in the scientific literature, and light and scanning electronic microscopy images are presented. S. vilamae and D. valida f. major are cited for the first time out of their type localities, this last taxa observed for the first time in the world since 1894. Besides, N. pseudogracilis is cited as a new species for Bolivia and the ultrastructure of this taxon and D. valida f. major were illustrated for the first time.
The performance of two 464-L high rate algal ponds (HRAPs) treating 20- and 10-folds diluted swin... more The performance of two 464-L high rate algal ponds (HRAPs) treating 20- and 10-folds diluted swine manure at 10 days of hydraulic residence time was evaluated under continental climatic conditions in Castilla y Leon (Spain) from January to October. Under optimum environmental conditions (from July to September), both HRAPs supported a stable and efficient carbon and nitrogen oxidation performance, with average COD and TKN removal efficiencies of 76 ± 11% and 88 ± 6%, respectively, and biomass productivities ranging from 21 to 28 g/m2 d. Nitrification was identified as the main TKN removal mechanism at dissolved oxygen concentrations higher than 2 mg/L (accounting for 80–86% of the TKN removed from January to May and for 54% from July to September). On the other hand, empirical evidences of a simultaneous nitrification–denitrification process were found at dissolved oxygen concentrations lower than 0.5 mg/L (high organic loading rates). However, despite the achievement of excellent COD and nitrogen oxidation performance, phosphorous removal efficiencies lower than 10% were recorded in both HRAPs probably due to the high buffer capacity of the piggery wastewater treated (absence of abiotic pH-mediated View the MathML source precipitation). Finally, a detailed monitorization of the dynamics of microalgae population revealed that the combination of moderate temperatures/solar irradiances and high organic loading rates, prevailing during late spring and summer, supported higher microalgae diversities than those found during winter conditions.
Coagulation-flocculation followed by a static decanter (StD) or a dissolved air flotation system ... more Coagulation-flocculation followed by a static decanter (StD) or a dissolved air flotation system (DAFAST) can reduce highly the energetic and production cost of treating urban wastewater in a high rate algal ponds (HRAP). Undesired Flotation or auto-flotation phenomenon took place during the operation of StD, even at very favourable settling conditions, therefore StD seem to be not very promising as method of microalgae pre-concentration. On the other hand, DAFAST operated under the addition of 20 ppm of coagulant and 5 ppm of cationic flocculant provided and effluent that fits the most restrictive limits of discharge (91/271/EC), averaging 20pmmTSS and 70 ppm COD, and reaching a concentration factor almost of 100.
With the hypothesis that light supply can impact the removal of veterinary antibiotics during liv... more With the hypothesis that light supply can impact the removal of veterinary antibiotics during livestock wastewater treatment in high rate algal ponds (HRAPs), this study was undertaken to determine the mechanisms of tetracycline removal in these systems. For this purpose, two HRAPs were fed with synthetic wastewater for 46 days before tetracycline was added at 2 mg L(-1) to the influent of one of the reactors (Te-HRAP). From day 62, dissolved tetracycline removal stabilized around 69 ± 1% in the Te-HRAP and evidence from batch assays suggests that this removal was mainly caused by photodegradation and biosorption. Tetracycline addition was followed by the deflocculation of the Te-HRAP biomass but had otherwise no apparent impact on the removal of the chemical oxygen demand (COD) and biomass productivity. The results from the batch assays also suggested that the light-shading and/or pollutant-sequestrating effects of the biomass limited tetracycline removal in the pond. For the first time, these results demonstrate that the shallow geometry of HRAPs is advantageous to support the photodegradation of antibiotics during wastewater biological treatment but that the presence of these pollutants could hamper biomass recovery. These findings have significant implications for algal-based environmental biotechnologies and must be confirmed under field conditions.
During a biological survey carried out in five shallow, high-altitude saline lakes of the Bolivia... more During a biological survey carried out in five shallow, high-altitude saline lakes of the Bolivian Altiplano in 2009, six unknown diatom
taxa were found in various lake populations. Detailed light and scanning electron microscopy observations allowed the description of the
following new taxa: Navicula venetoides (distinguished from N. veneta Kützing by having coarser lineate striae), Pinnularia boliviana
(similar to P. rhombarea var. halophila Krammer but with coarser striae and a narrower central area), Nitzschia sansimoni (morphologically
close to N. supralitorea Lange-Bertalot, the latter having denser striae), Surirella striatula var. halophila (differing from the nominate and
other varieties in a distinctly heteropolar outline and the presence of denser fibulae) and S. moralesii (with large, strictly isopolar valves
and a deep pervalvar depression). Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical
implications of these findings, are briefly discussed.
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platensis), one euglenophyt (Euglena viridis) and two microalgae consortia were evaluated for their ability
to support carbon, nitrogen and phosphorous removal in symbiosis with activated sludge bacteria during
the biodegradation of four and eight times diluted piggery wastewater in batch tests. C. sorokiniana and E.
viridis were capable of supporting the biodegradation of four and eight times diluted wastewater. On the
other hand, while S. obliquus and the consortia isolated from a swine manure stabilization pond were only
able to grow in eight times diluted wastewater, S. platensis and the consortium isolated from a high rate
algal pond treating swine manure were totally inhibited regardless of the dilution applied. TOC removal
efficiencies (RE) ranging from 42% to 55% and NH4
+-RE from 21% to 39% were recorded in the tests exhibiting
photosynthetic oxygenation. The similar oxygen production rates exhibited by the tested microalgae
under autotrophic conditions (from 116 to 133 mg O2 Lÿ1 dÿ1) suggested that factors other than the photosynthetic
oxygenation potential governed piggery wastewater biodegradation. Microalgal tolerance
towards NH3 was hypothesized as the key selection criterion. Further studies in a continuous algal–bacterial
photobioreactor inoculated with C. sorokiniana, S. obliquus and S. platensis showed that C. sorokiniana,
the species showing the highest NH3-tolerance, rapidly outcompeted the rest of the microalgae
during the biodegradation of eight times diluted wastewater, achieving TOC and NH4
+-RE comparable
to those recorded in the batch biodegradation tests."
taxa were found in various lake populations. Detailed light and scanning electron microscopy observations allowed the description of the
following new taxa: Navicula venetoides (distinguished from N. veneta Kützing by having coarser lineate striae), Pinnularia boliviana
(similar to P. rhombarea var. halophila Krammer but with coarser striae and a narrower central area), Nitzschia sansimoni (morphologically
close to N. supralitorea Lange-Bertalot, the latter having denser striae), Surirella striatula var. halophila (differing from the nominate and
other varieties in a distinctly heteropolar outline and the presence of denser fibulae) and S. moralesii (with large, strictly isopolar valves
and a deep pervalvar depression). Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical
implications of these findings, are briefly discussed.
platensis), one euglenophyt (Euglena viridis) and two microalgae consortia were evaluated for their ability
to support carbon, nitrogen and phosphorous removal in symbiosis with activated sludge bacteria during
the biodegradation of four and eight times diluted piggery wastewater in batch tests. C. sorokiniana and E.
viridis were capable of supporting the biodegradation of four and eight times diluted wastewater. On the
other hand, while S. obliquus and the consortia isolated from a swine manure stabilization pond were only
able to grow in eight times diluted wastewater, S. platensis and the consortium isolated from a high rate
algal pond treating swine manure were totally inhibited regardless of the dilution applied. TOC removal
efficiencies (RE) ranging from 42% to 55% and NH4
+-RE from 21% to 39% were recorded in the tests exhibiting
photosynthetic oxygenation. The similar oxygen production rates exhibited by the tested microalgae
under autotrophic conditions (from 116 to 133 mg O2 Lÿ1 dÿ1) suggested that factors other than the photosynthetic
oxygenation potential governed piggery wastewater biodegradation. Microalgal tolerance
towards NH3 was hypothesized as the key selection criterion. Further studies in a continuous algal–bacterial
photobioreactor inoculated with C. sorokiniana, S. obliquus and S. platensis showed that C. sorokiniana,
the species showing the highest NH3-tolerance, rapidly outcompeted the rest of the microalgae
during the biodegradation of eight times diluted wastewater, achieving TOC and NH4
+-RE comparable
to those recorded in the batch biodegradation tests."
taxa were found in various lake populations. Detailed light and scanning electron microscopy observations allowed the description of the
following new taxa: Navicula venetoides (distinguished from N. veneta Kützing by having coarser lineate striae), Pinnularia boliviana
(similar to P. rhombarea var. halophila Krammer but with coarser striae and a narrower central area), Nitzschia sansimoni (morphologically
close to N. supralitorea Lange-Bertalot, the latter having denser striae), Surirella striatula var. halophila (differing from the nominate and
other varieties in a distinctly heteropolar outline and the presence of denser fibulae) and S. moralesii (with large, strictly isopolar valves
and a deep pervalvar depression). Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical
implications of these findings, are briefly discussed.