Sema Şirin - Academia.edu (original) (raw)

Papers by Sema Şirin

Bioresource technology, 2015

The feasibility of using the mixture of seawater and municipal wastewater; (1) the wastewater bef... more The feasibility of using the mixture of seawater and municipal wastewater; (1) the wastewater before activated sludge tank, just after primary settling (BAS) and (2) the wastewater after activated sludge tank, just before addition of polymer flocculants (AAS); as culture medium for the cultivation of marine microalgae Nannochloropsis oculata was investigated. 10% BAS, 20% BAS and 10% AAS, 20% AAS, 50% AAS, 70% AAS, 100% AAS effluent loadings were well adapted to used wastewater. Sufficient dry weights obtained (345-406 mg L(-1)) with growth rates 0.37-0.45 for aerated cultures. High TN and TP removals (∼74-90%) were achieved. Harvesting technique for grown cultures was also studied with natural sedimentation and pH induced flocculation. By alkalinity induced flocculation, at pH values of 10.50, high recovery of the cells (∼80%) achieved with high sedimentation rates in 10 min. The flocculation efficiencies decreased, sedimentation rates increased with the increase of the cell concen...

Environmental technology, Jan 6, 2015

Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from ... more Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from algae. This paper presents experimental results for a cost-effective system to harvest Chaetoceros calcitrans, using natural sedimentation; flocculation; and inducing pH. No efficient sedimentation of microalgae cells was observed only by gravity. By alkalinity induced flocculation, at pH value of 9.51, 86% recovery of the cells achieved with sedimentation rate 125 cm/h and concentration factor 4 (volume/volume; v/v) in 10 minutes. The maximum photochemical quantum yield of PSII (Fv/Fm) of concentrated cells was almost the same as fresh culture (0.621). Commercial flocculants, aluminum sulfate and poly aluminum chloride, were also successful in harvesting the studied algae cells. Optimum concentration of AS could be concluded as 10 ppm with 87.6% recovery and 7.10 concentration factor (v/v) in 30 min for cost efficient harvesting, whereas for PAC 20 ppm with 74% recovery and 6.6 concentr...

Bioresource Technology, 2013

h i g h l i g h t s " Pre-concentration methods for high lipid content microalga species were stu... more h i g h l i g h t s " Pre-concentration methods for high lipid content microalga species were studied. " Dewatering with autoflocculation is found promising. " Characteristic properties of pre-concentrated samples were evaluated and compared. " Viscosity, PSD and Ca/Mg ions of pre-concentrated samples were analysed.

Journal of Applied Phycology, 2012

The purpose of this study was to explore efficient methods of harvesting the microalga Phaeodacty... more The purpose of this study was to explore efficient methods of harvesting the microalga Phaeodactylum tricornutum. Natural sedimentation experiments, performed at different light and temperature conditions, did not yield significant improvements in efficiency even after 1 week. When alkalinity-induced flocculation was performed, both the flocculation efficiency and the concentration factor dramatically improved at pH=9.75 (0.5-0.7 units over the original pH of the culture) after 10 min settling time. Sedimentation rates are documented at pH ranging between pH 9.75 and 11.0. The results of the application of two conventional flocculants used in wastewater treatment, polyaluminium chloride and aluminium sulphate, are also presented. Chitosan was also used as a natural flocculating agent to improve possible contamination problems in the downstream process. pH was adjusted in order to determine optimum flocculation efficiency of chitosan in combination with a high concentration factor. Satisfactory results were found with chitosan at an adjusted pH of 9.9 using concentrations as low as 20 mg L −1 , after testing a flocculant range of 5-200 mg L −1 .

Bioresource technology, 2015

The feasibility of using the mixture of seawater and municipal wastewater; (1) the wastewater bef... more The feasibility of using the mixture of seawater and municipal wastewater; (1) the wastewater before activated sludge tank, just after primary settling (BAS) and (2) the wastewater after activated sludge tank, just before addition of polymer flocculants (AAS); as culture medium for the cultivation of marine microalgae Nannochloropsis oculata was investigated. 10% BAS, 20% BAS and 10% AAS, 20% AAS, 50% AAS, 70% AAS, 100% AAS effluent loadings were well adapted to used wastewater. Sufficient dry weights obtained (345-406 mg L(-1)) with growth rates 0.37-0.45 for aerated cultures. High TN and TP removals (∼74-90%) were achieved. Harvesting technique for grown cultures was also studied with natural sedimentation and pH induced flocculation. By alkalinity induced flocculation, at pH values of 10.50, high recovery of the cells (∼80%) achieved with high sedimentation rates in 10 min. The flocculation efficiencies decreased, sedimentation rates increased with the increase of the cell concen...

Environmental technology, Jan 6, 2015

Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from ... more Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from algae. This paper presents experimental results for a cost-effective system to harvest Chaetoceros calcitrans, using natural sedimentation; flocculation; and inducing pH. No efficient sedimentation of microalgae cells was observed only by gravity. By alkalinity induced flocculation, at pH value of 9.51, 86% recovery of the cells achieved with sedimentation rate 125 cm/h and concentration factor 4 (volume/volume; v/v) in 10 minutes. The maximum photochemical quantum yield of PSII (Fv/Fm) of concentrated cells was almost the same as fresh culture (0.621). Commercial flocculants, aluminum sulfate and poly aluminum chloride, were also successful in harvesting the studied algae cells. Optimum concentration of AS could be concluded as 10 ppm with 87.6% recovery and 7.10 concentration factor (v/v) in 30 min for cost efficient harvesting, whereas for PAC 20 ppm with 74% recovery and 6.6 concentr...

Bioresource Technology, 2013

h i g h l i g h t s " Pre-concentration methods for high lipid content microalga species were stu... more h i g h l i g h t s " Pre-concentration methods for high lipid content microalga species were studied. " Dewatering with autoflocculation is found promising. " Characteristic properties of pre-concentrated samples were evaluated and compared. " Viscosity, PSD and Ca/Mg ions of pre-concentrated samples were analysed.

Journal of Applied Phycology, 2012

The purpose of this study was to explore efficient methods of harvesting the microalga Phaeodacty... more The purpose of this study was to explore efficient methods of harvesting the microalga Phaeodactylum tricornutum. Natural sedimentation experiments, performed at different light and temperature conditions, did not yield significant improvements in efficiency even after 1 week. When alkalinity-induced flocculation was performed, both the flocculation efficiency and the concentration factor dramatically improved at pH=9.75 (0.5-0.7 units over the original pH of the culture) after 10 min settling time. Sedimentation rates are documented at pH ranging between pH 9.75 and 11.0. The results of the application of two conventional flocculants used in wastewater treatment, polyaluminium chloride and aluminium sulphate, are also presented. Chitosan was also used as a natural flocculating agent to improve possible contamination problems in the downstream process. pH was adjusted in order to determine optimum flocculation efficiency of chitosan in combination with a high concentration factor. Satisfactory results were found with chitosan at an adjusted pH of 9.9 using concentrations as low as 20 mg L −1 , after testing a flocculant range of 5-200 mg L −1 .