The Experts below are selected from a list of 5397 Experts worldwide ranked by ideXlab platform
Nagamany Nirmalakhandan - One of the best experts on this subject based on the ideXlab platform.
-
Algal biofuels from urban wastewaters maximizing biomass yield using nutrients recycled from hydrothermal processing of biomass
Bioresource Technology, 2015Co-Authors: Thinesh Selvaratnam, Nagamany Nirmalakhandan, Ambica Koushik Pegallapati, Harvind K Reddy, N Kanapathipillai, Shuguang Deng, Peter J LammersAbstract:Abstract Recent studies have proposed Algal Cultivation in urban wastewaters for the dual purpose of waste treatment and bioenergy production from the resulting biomass. This study proposes an enhancement to this approach that integrates Cultivation of an acidophilic strain, Galdieria sulphuraria 5587.1, in a closed photobioreactor (PBR); hydrothermal liquefaction (HTL) of the wet Algal biomass; and recirculation of the nutrient-rich aqueous product (AP) of HTL to the PBR to achieve higher biomass productivity than that could be achieved with raw wastewater. The premise is that recycling nutrients in the AP can maintain optimal C, N and P levels in the PBR to maximize biomass growth to increase energy returns. Growth studies on the test species validated growth on AP derived from HTL at temperatures from 180 to 300 °C. Doubling N and P concentrations over normal levels in wastewater resulted in biomass productivity gains of 20–25% while N and P removal rates also doubled.
-
energetic performance of photobioreactors for Algal Cultivation
Environmental Science and Technology Letters, 2014Co-Authors: Ambica Koushik Pegallapati, Yalini Arudchelvam, Nagamany NirmalakhandanAbstract:Microalgae are currently being investigated as a potential fuel crop. For algae to be an energy-efficient fuel crop, Cultivation systems and operating conditions that have been optimized for biomass productivity have to be refocused toward energy production. In this work, data from the literature on a variety of Algal photobioreactors (PBRs) were compiled to reassess them in terms of biomass productivity per unit energy input to the Cultivation process. This assessment showed that PBRs that have been optimized for biomass productivity without considering the energy input did not necessarily perform well in terms of energy efficiency. This review recommends that selection of Algal PBRs for energy production should consider optimal geometry for efficient utilization of incident light, and their operation should be based on the optimal sparging rate for efficient mixing to maximize energy efficiency.
-
internally illuminated photobioreactor for Algal Cultivation under carbon dioxide supplementation performance evaluation
Renewable Energy, 2013Co-Authors: Ambica Koushik Pegallapati, Nagamany NirmalakhandanAbstract:Abstract This study evaluated an internally illuminated photobioreactor (IIPBR) design for improving biomass productivity through better utilization of light and carbon dioxide-supplementation. Growth of Scenedesmus sp. and Nannochloropsis salina in an 18-L version of this design was evaluated under artificial light at varying CO2–air (vol/vol) ratios, but at constant air supply rate of 0.8 L min−1 corresponding to gas-to-culture volume ratio of 0.044 min−1. CO2–air ratios of 4% and 1% were found as the optimal for Scenedesmus sp., and N. salina, yielding volumetric productivities of 0.40 and 0.104 g dry L−1 d−1, respectively. Under continuous operation with regular harvesting at the optimal CO2–air ratios, constant biomass levels of 1.40 and 0.52 g dry L−1 were maintained with average biomass productions of 2.53 and 0.93 g dry day−1, for the two species, respectively. Based on volumetric biomass productivity per unit light energy input per unit incident area, performance of this IIPBR design is shown to be comparable to that of bubble column and airlift designs reported in the literature, but at much lower gas-to-culture volume ratio.
-
optimizing net energy gain in Algal Cultivation for biodiesel production
Bioresource Technology, 2012Co-Authors: Yalini Arudchelvam, Nagamany NirmalakhandanAbstract:Abstract An approach based on energy gain was utilized to optimize Algal Cultivation in bubble columns. Net energy gain was estimated considering the energy input for mixing and providing carbon dioxide, and the energy that can be generated from the lipids extracted from the Algal biomass. Energy input for sparging was minimized based on the gas-to-culture volume ratio and energy output from lipid production was maximized based on nitrate and CO2 levels. Sparging at a gas-to-culture volume ratio of 0.18 min−1 with CO2-enrichment of 0.5% and initial nitrate concentration of 1 mM was optimal for improving net energy gain with Nannochloropsis salina. Sparging with CO2-enriched air of 0.5% along with nitrogen starvation resulted in 50% more lipid productivity than sparging with ambient air.
-
feasibility of microAlgal Cultivation in a pilot scale airlift driven raceway reactor
Bioresource Technology, 2012Co-Authors: Balachandran Ketheesan, Nagamany NirmalakhandanAbstract:Abstract A Scenedesmus sp. was cultivated in a 23-L airlift-driven raceway reactor under artificial lighting and laboratory conditions, in batch and continuous modes. In batch mode, a maximum volumetric biomass productivity of 0.085 dry g L −1 day −1 was achieved under sparging at a CO 2 -to-air ratio of 1%, and a maximum CO 2 utilization efficiency of 33% was achieved at a CO 2 -to-air ratio of 0.25%. In continuous mode, the maximum volumetric biomass productivity was 0.19 dry g L −1 day −1 . Biomass productivities per unit power input achieved in this reactor configuration (0.60–0.69 dry g W −1 day −1 ) were comparable to or better than those reported in the literature for different photobioreactor designs (0.10–0.51 dry g W −1 day −1 ). Based on the energy-efficient productivity and the high CO 2 utilization efficiency demonstrated in this study, the proposed airlift-driven raceway design holds promise for cost-effective Algal Cultivation.
Martin Gross - One of the best experts on this subject based on the ideXlab platform.
-
Biofilm-based Algal Cultivation systems
Applied Microbiology and Biotechnology, 2015Co-Authors: Martin Gross, Darren Jarboe, Zhiyou WenAbstract:Biofilm-based Algal Cultivation has received increased attention as a potential platform for Algal production and other applications such as wastewater treatment. Algal biofilm Cultivation systems represent an alternative to the suspension-based systems that have yet to become economically viable. One major advantage of Algal biofilm systems is that algae can be simply harvested through scraping and thus avoid the expensive harvesting procedures used in suspension-based harvesting such as flocculation and centrifugation. In recent years, an assortment of Algal biofilm systems have been developed with various design configurations and biomass production capacities. This review summarizes the state of the art of different Algal biofilm systems in terms of their design and operation. Perspectives for future research needs are also discussed to provide guidance for further development of these unique Cultivation systems.
-
use of wavelength selective optical light filters for enhanced microAlgal growth in different Algal Cultivation systems
Bioresource Technology, 2015Co-Authors: Clayton Michael, Martin Gross, Matteo Del Ninno, Zhiyou WenAbstract:Abstract This work is to use thin film nano-materials as light filters to selectively transmit certain wavelengths from natural sunlight to Algal culture. A red light filter (620–710 nm) and blue filter (450–495 nm) were evaluated. Algae were grown in flasks, flat panel reactors, and rotating Algal biofilm (RAB) system. It was found that the light filters did not improve Algal growth in flask cultures, probably due to the additional reflection of light by the glass wall of the flasks. However, the light filters significantly ( P P > 0.05). The research shows a great potential of using light filters to improve microAlgal growth.
-
development and optimization of biofilm based Algal Cultivation
2015Co-Authors: Martin GrossAbstract:This dissertation describes research done on biofilm based Algal Cultivation systems. The system that was developed in this work is the revolving Algal biofilm Cultivation system (RAB). A raceway-retrofit, and a trough-based pilot-scale RAB system were developed and investigated. Each of the systems significantly outperformed a control raceway pond in side-by-side tests. Furthermore the RAB system was found to require significantly less water than the raceway pond based Cultivation system. Lastly a TEA/LCA analysis was conducted to evaluate the economic and life cycle of the RAB Cultivation system in comparison to raceway pond. It was found that the RAB system was able to grow algae at a lower cost and was shown to be profitable at a smaller scale than the raceway pond style of Algal Cultivation. Additionally the RAB system was projected to have lower GHG emissions, and better energy and water use efficiencies in comparison to a raceway pond system. Furthermore, fundamental research was conducted to identify the optimal material for algae to attach on. A total of 28 materials with a smooth surface were tested for initial cell colonization and it was found that the tetradecane contact angle of the materials had a good correlation with cell attachment. The effects of surface texture were evaluated using mesh materials (nylon, polypropylene, high density polyethylene, polyester, aluminum, and stainless steel) with openings ranging from 0.05–6.40 mm. It was found that both surface texture and material composition influence Algal attachment.
-
yearlong evaluation of performance and durability of a pilot scale revolving Algal biofilm rab Cultivation system
Bioresource Technology, 2014Co-Authors: Martin GrossAbstract:Abstract Current Algal Cultivation has been mainly performed in open ponds or photobioreactors in which Algal cells are suspended and harvested through flocculation and centrifugation. A unique attachment based Revolving Algal Biofilm (RAB) Cultivation system was recently developed for easy biomass harvest with enhanced biomass productivity. The objective of this research was to evaluate the performance (durability, Algal growth, and the geometry) of the RAB system at pilot-scale. A yearlong test of the RAB system was successfully conducted at a greenhouse facility at Boone, Iowa, USA. The RAB resulted in an average of 302% increase in biomass productivity compared to a standard raceway pond, with a maximum biomass productivity (ash free) of 18.9 g/m 2 -day being achieved. The RAB with a vertical configuration generated higher productivity than the triangular RAB. Collectively, the research shows that the RAB as an efficient Algal culture system has great potential for being deployed at commercial scale.
-
development and optimization of Algal Cultivation systems
2013Co-Authors: Martin GrossAbstract:This thesis describes research done on two novel algae Cultivation systems. The first system was an attached Algal growth system to facilitate biomass harvest with improved biomass yield. In the attached system, Algal cells were grown on the surface of a material rotating between the nutrient-rich liquid phase and the carbon dioxide-rich gaseous phase. The Algal cells from the attached growth system were harvested by simply scraping off the Algal biofilm. The operation conditions of the attached growth system were optimized to improve biomass productivity. A harvesting frequency of 7 days with a rotational speed of 4 rpm resulted in the highest cell productivity. Changing the CO2 content from atmospheric CO2 level (~300ppm) to 3000 ppm did not significantly change growth performance. The attached growth system resulted in a biomass productivity of 10.5 g*m -2 *day -1 . The biomass harvested from the attached system had higher carbohydrate content, but lower lipid content compared to the suspension culture system. Other research presented in this thesis was to grow the microalga Chlorella vulgaris under simulated microgravity conditions to evaluate CO2 consumption and O2 generation rates. The effects of hydraulic retention time, gas flow rate, and CO2 concentration on Algal growth were investigated. All the three factors significantly influenced CO2 consumption and O2 generation rates. A statistical response surface design was used to optimize these two parameters. The optimal conditions for CO2 consumption and O2 generation were determined to be 6.59 days hydraulic retention time, 0.153 vvm gas flow rate, and 0.80% CO2 concentration. Algae growth and CO2 consumption rates in microgravity were not significantly different than growth at earth (1 g) gravity. A hollow fibre membrane photobioreactor was also developed which enhanced CO2 consumption rates.
Balachandran Ketheesan - One of the best experts on this subject based on the ideXlab platform.
-
feasibility of microAlgal Cultivation in a pilot scale airlift driven raceway reactor
Bioresource Technology, 2012Co-Authors: Balachandran Ketheesan, Nagamany NirmalakhandanAbstract:Abstract A Scenedesmus sp. was cultivated in a 23-L airlift-driven raceway reactor under artificial lighting and laboratory conditions, in batch and continuous modes. In batch mode, a maximum volumetric biomass productivity of 0.085 dry g L −1 day −1 was achieved under sparging at a CO 2 -to-air ratio of 1%, and a maximum CO 2 utilization efficiency of 33% was achieved at a CO 2 -to-air ratio of 0.25%. In continuous mode, the maximum volumetric biomass productivity was 0.19 dry g L −1 day −1 . Biomass productivities per unit power input achieved in this reactor configuration (0.60–0.69 dry g W −1 day −1 ) were comparable to or better than those reported in the literature for different photobioreactor designs (0.10–0.51 dry g W −1 day −1 ). Based on the energy-efficient productivity and the high CO 2 utilization efficiency demonstrated in this study, the proposed airlift-driven raceway design holds promise for cost-effective Algal Cultivation.
-
Development of a new airlift-driven raceway reactor for Algal Cultivation
Applied Energy, 2011Co-Authors: Balachandran Ketheesan, Nagamany NirmalakhandanAbstract:This paper presents the development and analysis of a new airlift-driven raceway reactor configuration for energy-efficient Algal Cultivation. A theoretical analysis of the energy requirements for traditional paddlewheel-driven raceway reactors and the proposed airlift-driven raceway reactors is presented. A hydrodynamic model was developed to predict the liquid circulation velocity in the reactor system based on theoretical energy balance. The predicted liquid velocity agreed well with experimentally measured liquid velocity with r2=0.89. Based on the results of this analysis, the energy required for maintaining typical raceway velocity of 14cm/s for mixing and keeping the cultures in suspension in a paddlewheel-driven raceway could be reduced by as much as 80% with the proposed configuration. Growth of Scenedesmus sp. was evaluated in a laboratory scale, 20L version of the proposed reactor configuration using artificial lighting under ambient temperatures without any supplementary carbon dioxide sparging. The volumetric Algal biomass productivity achieved in the proposed configuration (0.16±0.03dryg/Lday) is comparable or better than that reported in the literature for paddlewheel-driven raceways.
Zhiyou Wen - One of the best experts on this subject based on the ideXlab platform.
-
Biofilm-based Algal Cultivation systems
Applied Microbiology and Biotechnology, 2015Co-Authors: Martin Gross, Darren Jarboe, Zhiyou WenAbstract:Biofilm-based Algal Cultivation has received increased attention as a potential platform for Algal production and other applications such as wastewater treatment. Algal biofilm Cultivation systems represent an alternative to the suspension-based systems that have yet to become economically viable. One major advantage of Algal biofilm systems is that algae can be simply harvested through scraping and thus avoid the expensive harvesting procedures used in suspension-based harvesting such as flocculation and centrifugation. In recent years, an assortment of Algal biofilm systems have been developed with various design configurations and biomass production capacities. This review summarizes the state of the art of different Algal biofilm systems in terms of their design and operation. Perspectives for future research needs are also discussed to provide guidance for further development of these unique Cultivation systems.
-
use of wavelength selective optical light filters for enhanced microAlgal growth in different Algal Cultivation systems
Bioresource Technology, 2015Co-Authors: Clayton Michael, Martin Gross, Matteo Del Ninno, Zhiyou WenAbstract:Abstract This work is to use thin film nano-materials as light filters to selectively transmit certain wavelengths from natural sunlight to Algal culture. A red light filter (620–710 nm) and blue filter (450–495 nm) were evaluated. Algae were grown in flasks, flat panel reactors, and rotating Algal biofilm (RAB) system. It was found that the light filters did not improve Algal growth in flask cultures, probably due to the additional reflection of light by the glass wall of the flasks. However, the light filters significantly ( P P > 0.05). The research shows a great potential of using light filters to improve microAlgal growth.
-
production of ω 3 polyunsaturated fatty acids from cull potato using an algae culture process
Applied Biochemistry and Biotechnology, 2007Co-Authors: Zhanyou Chi, Yan Liu, Craig Frear, Zhiyou Wen, Shulin ChenAbstract:Algal Cultivation for converting cull potato to docosahexaenoic acid (DHA) was studied. Schizochytrium limacinum SR21 was selected as the better producing strain, compared with Thraustochytrium aureum because of higher cell density and DHA content. Used as both carbon and nitrogen source, an optimal ratio of hydrolyzed potato broth in the culture medium was determined as 50%, with which the highest production of 21.7 g/L dry algae biomass and 5.35 g/L DHA was obtained, with extra glucose supplemented. Repeat culture further improved the cell density but not fed batch culture, suggesting limited growth was most likely caused by metabolites inhibition.
Martin Romantschuk - One of the best experts on this subject based on the ideXlab platform.
-
integrated utilization of microalgae cultured in aquaculture wastewater wastewater treatment and production of valuable fatty acids and tocopherols
Journal of Applied Phycology, 2019Co-Authors: Marika Tossavainen, Katariina Tuulikki Lahti, Minnamari Edelmann, Reetta Eskola, Annamaija Lampi, Vieno Piironen, Pasi Korvonen, Anne Ojala, Martin RomantschukAbstract:MicroAlgal Cultivation in aquaculture wastewater (AWW) from recirculating aquaculture systems (RAS) is an approach for combined production of valuable Algal biomass and AWW treatment. The growth, nutrient uptake, fatty acid (FA) profile, and tocopherol content of mixed Algal cultures of Euglena gracilis with Selenastrum grown in AWWs from pikeperch (Sander lucioperca) and catfish (Clarias anguillaris) RAS were studied. The highest Algal biomass (1.5 g L−1), lipid (84.9 mg L−1), and tocopherol (877.2 μg L−1) yields were achieved in sludge-amended pike perch AWW. Nutrient removal rates in experiments were 98.9–99.5 and 98.4–99.8% for NH4-N and PO4-P, and 75.4–89.2% and 84.3–95.7% for TN and TP, respectively, whereas the COD was reduced by 45.8–67.6%. Biomass EPA and DHA content met, while ARA and tocopherol content exceeded the requirements for fish feed. Algal Cultivation in AWWs is a promising alternative for AWW treatment while providing a replacement for fish oil in feed.