RESUMEN
In this study, the effect of α-Fe2O3 nanoparticles spiking in urban wastewater (UWW) on growth rate, wastewater treatment ability and bioproducts generation of C. vulgaris and Spirulina was investigated and compared with pure cultivation system. The biomass concentration of C. vulgaris and Spirulina improved by 20 % and 39 % at 10 and 15 mg/L α-Fe2O3, respectively while the both microalgae growth pattern fitted better with Gompertz simulation after treatment with α-Fe2O3. The nutrients mass balance revealed that 1 g of treated C. vulgaris and Spirulina could uptake more COD, TN and TP in comparison to the untreated cells. The lipid generation increased remarkably (C. vulgaris: 45 % and Spirulina: 72 %) after α-Fe2O3 treatment. While, the addition of α-Fe2O3 showed no significant impact on the protein and carbohydrate productivity. Overall, this study evangelize the role of nanoparticles on promoting microalgae applications as a sustainable approach for UWW treatment and promising feedstock for biofuel production.
Asunto(s)
Chlorella vulgaris , Compuestos Férricos , Microalgas , Purificación del Agua , Microalgas/metabolismo , Nutrientes , Biomasa , Nanopartículas Magnéticas de Óxido de Hierro , Expresión Génica , Chlorella vulgaris/metabolismoRESUMEN
In this study, a novel internally illuminated mirror photobioreactor (IIM-PBR) was designed to improve microalgae biomass production through providing a homogenous light distribution in cultivation medium. The performance of the IIM-PBR was compared with internally illuminated control photobioreactor (IIC-PBR) and externally illuminated control photobioreactor (EIC-PBR) in terms of cell growth, wastewater treatment and bioproducts generation. Compared with the IIC-PBR and EIC-PBR, the IIM-PBR increased microalgae growth rate up to 60 % and 30%, respectively. Municipal wastewater treatment revealed that the IIM-PBR could significantly improve nutrients removal as the final removal efficiencies of 90%, 95% and 90% were obtained for nitrate, phosphate and COD, respectively. Moreover, the IIM-PBR increased the total bioproducts production by 89% and 46% compared to in the IIC-PBR and EIC-PBR, respectively. Based on the energy consumption calculation, the mirror's light-reflective properties of the IIM-PBR resulted in a significant reduction of total energy consumption (â¼10 times).
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Microalgas , Fotobiorreactores , Luz , Nitratos , Fosfatos , BiomasaRESUMEN
Microalgal biomass harvesting and cell disruption are the main bottlenecks for downstream processing of microalgae such as high-value bioproducts extraction and biofuels production. In this study, we evaluated the performance of dual flocculation between cationic surfactants and bio-polymer of chitosan for simultaneous biomass harvesting and bioproducts extraction from Chlorella sorokiniana microalgae. First, the effects of individual natural flocculants of chitosan and two cationic surfactants: cetyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium bromide (DTAB) on biomass harvesting were studied. Next, the synergistic effect of dual flocculation between the cationic surfactants and chitosan on harvesting efficiency, time and flocculant dosage was investigated. Finally, we evaluated the potential of high value bioproducts extraction from microalgae after the individual and dual flocculation processes. Zeta potential analysis and microscopic images were employed to achieve mechanistic understanding. Maximum biomass harvesting efficiencies of 85 %, 88 % and 78 % were achieved using individual flocculants of chitosan, CTAB and DTAB, under their optimum dosages of 100, 400 and 4000 mg/L, respectively. A significant synergistic effect of dual flocculation between chitosan (C) and cationic surfactants on biomass harvesting efficiency (CTAB-C: 99 % and DTAB-C: 97 %), settling time (CTAB-C: 2 min and DTAB-C: 5 min) and optimum dosage of surfactants (CTAB-C: 100 mg/L and DTAB-C: 1000 mg/L) was observed. The synergistic effect was associated with multiple flocculation mechanisms of charge neutralization and bridging induced by cationic surfactants and chitosan, respectively. Furthermore, bioproducts recovery efficiencies of 12 %, 25 % and 15 % of cell dry weight were achieved for protein, carbohydrate and lipid, respectively by using dual flocculation of CTAB surfactant and chitosan at much lower dosage of 100 mg/L.
Asunto(s)
Quitosano , Chlorella , Microalgas , Biomasa , Floculación , Polímeros , Cetrimonio , TensoactivosRESUMEN
A novel hexagonal airlift flat plate (HAFP) photobioreactor was designed to improve microalgae growth rate and compared with traditional flat plate (TFP) photobioreactor. The computational fluid dynamics (CFD) simulation was used to determine hydrodynamic parameters and optimal aeration rate in the photobioreactors. Additionally, the capability of the HAFP photobioreactor to enhance microalgae based CO2 bio-fixation and wastewater treatment were investigated. The results of CFD simulation indicated that the HAFP photobioreactor could improve hydrodynamic parameters of turbulence kinetic energy (TKE), average fluid velocity, dead zone (DZ), and water shear stress (WSS) up to 78 %, 41 %, 44 % and 40 %, respectively, under optimal aeration rate of 0.6 vvm. The proposed HAFP photobioreactor showed a drastic improvement in microalgae growth (up to 61 %). The maximum CO2 removal of 53.8 % and bio-fixation of 0.85 g L-1 d-1 were achieved in the HAFP photobioreactor which were approximately 70 % more than that in the TFP photobioreactor. The results suggested that the HAFP photobioreactor could accelerate nutrients removal and achieve remarkably higher efficiencies of 91 %, 99 %, 97 % and 93 % of ammonia (NH3), nitrate (NO3-), phosphate (PO43-) and chemical oxygen demand (COD) within seven days of cultivation.
Asunto(s)
Microalgas , Purificación del Agua , Biomasa , Dióxido de Carbono , Fotobiorreactores , Aguas ResidualesRESUMEN
In this research, the use of four different types of surfactants on biomass harvesting and extracellular polymeric substances (EPS) extrusion of Chlorella sorokiniana sp was investigated. The synergy between cationic surfactants and pH was tested to improve flocculation efficiency through the combined mechanism of charge neutralization, bridging and sweeping. Zeta potential and microscopic images were used to gain mechanistic understanding. The harvesting efficacy correlated positively with the biomass zeta potential and the surfactants alkyl-chain length; i.e., CTAB (88%) > DTAB (66%) > triton X-100 (41%) > SDS (11%). When the pH increased from 8 to 12, the harvesting efficiency was improved 12% and 39% for CTAB and DTAB, respectively. More interestingly, pH adjustment dramatically reduced the optimal dosages of CTAB and DTAB from 400 to 50 and 1000 to 300 mg/L, respectively. All selected surfactants could successfully release high value components of EPS such as protein and polysaccharide.