DOCSLIB.ORG

Experimental Studies of Vertical Mixing in an Open Channel Raceway for Algae Biofuel Production

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Experimental Studies of Vertical Mixing in an Open Channel Raceway for Algae Biofuel Production Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 8-2012 Experimental Studies of Vertical Mixing in an Open Channel Raceway for Algae Biofuel Production Ram Sudheer Voleti Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Aerospace Engineering Commons Recommended Citation Voleti, Ram Sudheer, "Experimental Studies of Vertical Mixing in an Open Channel Raceway for Algae Biofuel Production" (2012). All Graduate Theses and Dissertations. 1307. https://digitalcommons.usu.edu/etd/1307 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. EXPERIMENTAL STUDIES OF VERTICAL MIXING IN AN OPEN CHANNEL RACEWAY FOR ALGAE BIOFUEL PRODUCTION by Ram Sudheer Voleti A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Mechanical Engineering Approved: Dr. Byard D. Wood Dr. Clair J. Batty Major Professor Committee Member Dr. Leijun Li Dr. Barton L. Smith Committee Member Committee Member Dr. Mark R. McLellan Vice President for Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2012 ii Copyright © Ram Sudheer Voleti 2012 All Rights Reserved iii ABSTRACT Experimental Studies of Vertical Mixing in an Open Channel Raceway for Algae Biofuel Production by Ram Sudheer Voleti, Master of Science Utah State University, 2012 Major Professor: Dr. Byard D. Wood Department: Mechanical and Aerospace Engineering Turbulent mixing plays an important role in the distribution of sunlight, carbon dioxide, and nutrients for algae in the raceway ponds. For large-scale raceway ponds the choice of mixing technology still needs to be evaluated in order to prevent algae sedimentation and to enhance light utilization efficiency. In open ponds, mixing the algae culture is of great significance in terms of input energy costs and particularly productivity. A very small amount of research has been performed previously using different vortex generators in the algal raceway ponds, but the quantification of mixing depth relationships is not defined well. By accepting the premise from the literature review that mixing increases algal production, delta wings were selected to study mixing characteristics in the raceway. The main objective of this research was to study algae- raceway hydrodynamics with an emphasis on increasing vertical mixing. iv A clear acrylic raceway was designed and constructed for flow visualization studies. Experimental investigations were performed to quantify the vertical mixing with and without delta wings in a lab-scale raceway at approximately the same power input to the paddle wheel. Velocity vector profiles and turbulence parameters were measured using an Acoustic Doppler Velocimeter (ADV) at various locations along the entire length of the raceway. The results indicated that the addition of delta wings increases the vertical mixing intensity or circulation of algae cells over the raceway depth. Vortices were observed in the raceway up to a distance of around 3 m downstream of the delta wing. This sort of systematic vertical mixing plays an important role to produce the flashing light effect (light-dark cycles) on algae mass culture. In addition, turbulence dissipation rates were evaluated to compare them with the published literature and to estimate the microscales using the Kolmogorov hypothesis. Also, an energy model was developed to operate the paddlewheel-driven raceway with the delta wing. (123 pages) v PUBLIC ABSTRACT Experimental Studies of Vertical Mixing in an Open Channel Raceway for Algae Biofuel Production by Ram Sudheer Voleti, Master of Science Utah State University, 2012 Major Professor: Dr. Byard D. Wood Department: Mechanical and Aerospace Engineering The USU BioEnergy Center has been successful in developing algae feedstocks for renewable biofuels and bioproducts. The concept is to utilize and maximize algae feedstocks for liquid transportation fuels, biomass for burning and digestion, and high value co-products. It is theorized that increasing the mixing in open and closed algal production systems improves the productivity of the algae culture. A raceway cultivation system was chosen to examine the phenomena of mixing. Vertical mixing will provide more uniform exposure to sunlight for all of the algae in the raceway. The main focus of this research was to increase vertical mixing. Delta wing vortex generator was selected as a viable source of creating vertical mixing. A series of experiments were carried out to study the mixing characteristics in a lab-scale raceway that was designed specifically for raceway hydrodynamics. Finally, the results were discussed and appropriate conclusions drawn. vi ACKNOWLEDGMENTS I would like to express my highest regards and gratitude to my major professor and supervisor, Dr. Byard Wood, who continues to provide encouragement, guidance, support, and advice. I will be forever indebted to him for believing in me right from the beginning of my career as a research assistant at USU. I am thankful to Dr. Barton Smith for his class lectures, help, and input during the progress of my research. I would like to thank my committee members, Dr. Clair Batty, Dr. Leijun Li, and Dr. Barton Smith, for extending their service and support. I am thankful to all the current and past Raceway Hydraulics Research Group members, including Aaron, Blake, Dan, Garrett, Jayson, Justin, and Pete, for the support given by them during my research. Also, I would like to thank all the people who were involved directly or indirectly and helped in the construction of the clear acrylic raceway at USU Algae Energy Systems lab. I feel grateful to the USU BioEnergy Center and the US Department of Energy (Grant Number DE-EE0003114) for all the financial support. Finally, I am thankful to my wonderful family, teachers, relatives, and friends for their love and support, and for all the confidence and trust they put in me. Ram Sudheer Voleti vii CONTENTS Page ABSTRACT ................................................................................................................... iii PUBLIC ABSTRACT .................................................................................................... v ACKNOWLEDGMENTS ............................................................................................. vi LIST OF TABLES ......................................................................................................... ix LIST OF FIGURES ........................................................................................................ x ACRONYMS ............................................................................................................... xiv NOMENCLATURE ..................................................................................................... xv CHAPTER 1. INTRODUCTION .......................................................................................... 1 2. OBJECTIVES ................................................................................................. 4 3. LITERATURE REVIEW ............................................................................... 5 3.1. Effects of Turbulence on Algae Growth ............................................... 5 3.2. Mixing in Algal Raceway Ponds ........................................................ 10 4. APPROACH AND PROCEDURE ............................................................... 13 4.1. Experimental Setup ............................................................................. 13 4.1.1. Raceway Description ............................................................. 14 4.1.2. Delta Wing Setup ................................................................... 15 4.2. Preliminary Experiments..................................................................... 16 4.3. Acoustic Doppler Velocimeter Measurements ................................... 17 4.3.1. ADV Description and Principle of Operation ........................ 17 4.3.2. Sampling Frequency and Time .............................................. 21 4.3.3. Section-wise Grid Measurements .......................................... 24 viii 4.4. Data Analysis ...................................................................................... 27 4.4.1. Data Post Processing .............................................................. 27 4.4.2. Measurement Uncertainty Analysis ....................................... 30 4.4.3. Estimation of Turbulence Parameters .................................... 32 4.4.4. Estimation of Turbulence Dissipation Rates .......................... 33 4.5. Comparison of ADV and PIV Measurements .................................... 36 4.6. Power Measurements and Raceway Energy Model ............................ 37 5. EXPERIMENTAL RESULTS AND DISCUSSION ................................... 39 5.1. Comparison of ADV Data with PIV Data .......................................... 39 5.2. Velocity Vector Profiles ..................................................................... 40 5.2.1. Experiment Set 1 .................................................................... 41 5.2.2. Experiment Set 2 .................................................................... 43 5.2.3. Experiment Set 3 ...................................................................
Load more

Recommended publications
  • Algae Supplement to the Guidance Document “Points to Consider in the Preparation of TSCA Biotechnology Submissions for Microorganisms”
    Algae Supplement to the Guidance Document “Points to Consider in the Preparation of TSCA Biotechnology Submissions for Microorganisms” 1 Disclaimer: The contents of this document do not have the force and effect of law and are not meant to bind the public in any way. This document is intended only to provide clarity to the public regarding existing requirements under the law or agency policies. 2 TABLE OF CONTENTS I. INTRODUCTION ..................................................................................................................... 5 A. PURPOSE OF THIS SUPPLEMENT............................................................................... 5 B. RATIONALE FOR FOCUS ON ALGAE ........................................................................ 5 C. DEVELOPMENT OF THIS “ALGAE SUPPLEMENT” ............................................... 6 D. ORGANIZATION OF THIS “ALGAE SUPPLEMENT” .............................................. 6 II. INFORMATION USEFUL FOR RISK ASSESSMENT OF A GENETICALLY ENGINEERED ALGA ............................................................................................................. 7 A. RECIPIENT MICROORGANISM CHARACTERIZATION ....................................... 7 1. Taxonomy ......................................................................................................................... 7 2. General Description and Characterization ................................................................... 8 B. GE ALGA CHARACTERIZATION ...............................................................................
    [Show full text]
  • Fish Farming Technology Professor Simon Davies on Health & Nutrition That Yield up Nutritional Benefits Are Playing an and Erik Hampel on Fish Farming Technology
    FISH FARMING TECHNOLOGY CASE STUDY Pioneering North American RAS Facility embarks on 4th Decade of Operations - Krill - The novel ingredient to promote the health and growth of marine fish - Phytogenics - A sustainable January 2021 and eco-friendly solution for performing aquaculture - The utilisation of xylanase in diets for Pacific white shrimp See our archive and language editions on Litopenaeus vannamei your mobile! International Aquafeed - Volume 24 - Issue 01 International Aquafeed - Volume - Early Sturgeon Sex Discrimination: Proud supporter of Aquaculture without www.aquafeed.co.uk Frontiers UK CIO January 2021 www.fishfarmingtechnology.net Balanced by nature Shrimp farming without the guesswork: increase stocking Ecobiol® density and increase pathogen risk, decrease stocks and decrease profits – finding the right balance in shrimp production can be a guessing game. Evonik’s probiotic solution Ecobiol® helps for Aquaculture restore the balance naturally by disrupting unwanted bacteria proliferation and supporting healthy intestinal microbiota. Your benefit: sustainable and profitable shrimp farming without relying on antibiotics. [email protected] www.evonik.com/animal-nutrition Balanced by nature Shrimp farming without the guesswork: increase stocking Welcome to a New Year! WELCOMEthe entire range of fish farming activities as Ecobiol® density and increase pathogen risk, decrease stocks and decrease we pass through 2021 and it is this magazine’s profits – finding the right balance in shrimp production can be a guessing game. Evonik’s probiotic solution Ecobiol® helps We are very happy to have you with us for role to provide the information on nutrition, for Aquaculture restore the balance naturally by disrupting unwanted bacteria 2021 as this will be an exciting 12 months as we technology and personal experiences that proliferation and supporting healthy intestinal microbiota.
    [Show full text]
  • BIOLOGY 100 Munyawera, James University of Rwanda Contribution to the Optimization of Algal Production As Biomass for Generating
    BIOLOGY 100 Munyawera, James University of Rwanda Contribution to the Optimization of Algal Production as Biomass for Generating Biofuel Clement Ahishakiye ,University of Rwanda Birungi Martha Mwiza, University of Rwanda Algae are photosynthetic organism including macro and microalgae species and they mostly live in moist environment. Algae especially microalgae species are important due to high nutritional content mainly oil that can be used for production of biofuel as an alternative to petroleum products. Biofuel is a fuel produced through biological processing of photosynthetic matter. Aim of this study was to identify the algal species present in sample collected from Rwamamba marsh land and to determine their optimal growth conditions for biomass production. in order to produce biofuels in Rwanda. The isolation of algae strains was performed by using appropriate culture media and the identification by phenotypic characteristics based by microscopic observation. During the biomass production, a culture has been supplied with CO2 from a reaction produced by calcium carbonate and hydrochloric acid, another one was remained naturally with no CO2 supp. The effect of pH (6.5, 7.5, 8.0) on the growth of algae species was also evaluated. In the samples collected from different sites. Two different algal species were identified namely Chlorella sp. and Botryococcus sp. The result showed that Chlorella sp. grows better than Botryococcus sp. the optimum growth temperature for isolation was around 25oC. The culture of Chlorella sp in the medium with additional CO2 grow better than when there is no CO2 supply. The both Chlorella and Botryococcus species were grows best at the pH 7.5 and 8.0.
    [Show full text]
  • Industrial Algae Measurements October 2017 | Version 8.0
    Industrial Algae Measurements October 2017 | Version 8.0 A publication of ABO’s Technical Standards Committee © 2017 Algae Biomass Organization About the Algae Biomass Organization Founded in 2008, the Algae Biomass Organization (ABO) is a non-profit organization whose mission is to promote the development of viable commercial markets for renewable and sustainable products derived from algae. Our membership is comprised of people, companies, and organizations across the value chain. More information about the ABO, including membership, costs, benefits, members and their affiliations, is available at our website: www.algaebiomass.org. The Technical Standards Committee is dedicated to the following functions: • Developing and advocating algal industry standards and best practices • Liaising with ABO members, other standards organizations and government • Facilitating information flow between industry stakeholders • Reviewing ABO technical positions and recommendations For more information, please see: http://www.algaebiomass.org Staff Committees Executive Director – Matthew Carr Events Committee General Counsel – Andrew Braff, Wilson Sonsini Goodrich & Rosati Chair – Craig Behnke, Sapphire Program Chair – Jason Quinn, Colorado State University Administrative Coordinator – Barb Scheevel Administrative Assistant – Nancy Byrne Member Development Committee John Benemann, MicroBio Engineering Budget & Finance Committee Board of Directors Martin Sabarsky, Cellana Chair – Jacques Beaudry-Losique, Algenol Biofuels Bylaw & Governance Committee Vice
    [Show full text]
  • Part 1 General Provisions
    Utah Code Part 1 General Provisions 4-37-101 Title. This chapter is known as the "Aquaculture Act." Enacted by Chapter 153, 1994 General Session 4-37-102 Purpose statement -- Aquaculture considered a branch of agriculture. (1) The Legislature declares that it is in the interest of the people of the state to encourage the practice of aquaculture, while protecting the public fishery resource, in order to augment food production, expand employment, promote economic development, and protect and better utilize the land and water resources of the state. (2) The Legislature further declares that aquaculture is considered a branch of the agricultural industry of the state for purposes of any laws that apply to or provide for the advancement, benefit, or protection of the agricultural industry within the state. Amended by Chapter 378, 2010 General Session 4-37-103 Definitions. As used in this chapter: (1) "Aquaculture" means the controlled cultivation of aquatic animals. (2) (a) (i) "Aquaculture facility" means any tank, canal, raceway, pond, off-stream reservoir, or other structure used for aquaculture. (ii) "Aquaculture facility" does not include any public aquaculture facility or fee fishing facility. (b) Structures that are separated by more than 1/2 mile, or structures that drain to or are modified to drain to, different drainages, are considered separate aquaculture facilities regardless of ownership. (3) (a) "Aquatic animal" means a member of any species of fish, mollusk, crustacean, or amphibian. (b) "Aquatic animal" includes a gamete of any species listed in Subsection (3)(a). (4) "Fee fishing facility" means a body of water used for holding or rearing fish for the purpose of providing fishing for a fee or for pecuniary consideration or advantage.
    [Show full text]
  • Development and Optimization of Biofilm Based Algal Cultivation Martin Anthony Gross Iowa State University
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Development and optimization of biofilm based algal cultivation Martin Anthony Gross Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Agriculture Commons, Bioresource and Agricultural Engineering Commons, and the Oil, Gas, and Energy Commons Recommended Citation Gross, Martin Anthony, "Development and optimization of biofilm based algal cultivation" (2015). Graduate Theses and Dissertations. 14850. https://lib.dr.iastate.edu/etd/14850 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Development and optimization of biofilm based algal cultivation by Martin Anthony Gross A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Dual major: Agricultural and Biosystems Engineering/ Food Science and Technology Program of Study Committee: Dr. Zhiyou Wen, Co-Major Professor Dr. Lawrence Johnson, Co-Major Professor Dr. Jacek Koziel Dr. Kurt Rosentrater Dr. Say K Ong Iowa State University Ames, Iowa 2015 Copyright © Martin Anthony Gross, 2015. All rights reserved. ii TABLE OF CONTENTS Page ACKNOWLEDGMENTS
    [Show full text]
  • Algal Research 26 (2017) 436–444
    Algal Research 26 (2017) 436–444 Contents lists available at ScienceDirect Algal Research journal homepage: www.elsevier.com/locate/algal Effective control of Poterioochromonas malhamensis in pilot-scale culture of MARK Chlorella sorokiniana GT-1 by maintaining CO2-mediated low culture pH ⁎ Mingyang Maa,b,c, Danni Yuana,b,c, Yue Hea,b, Minsung Parka, Yingchun Gonga,b, , ⁎⁎ Qiang Hua,b,d,e, a Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China b Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China c University of Chinese Academy of Sciences, Beijing 100049, China d SDIC Microalgae Biotechnology Center, China Electronics Engineering Design Institute, Beijing 100142, China e Beijing Key Laboratory of Algae Biomass, Beijing 100142, China ARTICLE INFO ABSTRACT Keywords: Although predators in microalgal culture can often be protozoa reducing biomass productivity and culture Chlorella sorokiniana stability, there are few effective approaches to control them. This study investigated the effect of culture pH (i.e., Contamination control 6.0, 6.5, 7.0 and 7.5) maintained by supply of compressed air bubbles containing various concentrations of CO2 Poterioochromonas malhamensis on death of the flagellate Poterioochromonas malhamensis and several other protozoa in the culture of the green CO 2 microalgae Chlorella sorokiniana GT-1. C. sorokiniana GT-1 grew well at pH 6.0 and 6.5 and a sustainable biomass pH − concentration of 1.61 g L 1 was obtained from the cultures maintained at pH 6.5. The cultures maintained at Protozoan predator pH 7.0 and 7.5 collapsed on days 7 and 4 of culture, respectively, as a result of contamination by P.
    [Show full text]
  • NPDES Permit Fact Sheet for Tamgas Creek Hatchery, Metlakatla, Alaska
    Fact Sheet Tamgas Creek Hatchery Permit No. AK0028525 Fact Sheet The U.S. Environmental Protection Agency (EPA) Proposes to Issue a National Pollutant Discharge Elimination System (NPDES) Permit to Discharge Pollutants Pursuant to the Provisions of the Clean Water Act (CWA) to: Tamgas Creek Hatchery Mile 8 Hatchery Road Metlakatla, Alaska 99926 NPDES Permit Number: AK0028525 Public Notice Start Date: September 28, 2018 Public Notice Expiration Date: October 29, 2018 Technical Contact: Kai Shum 206-553-0060 [email protected] 1-800-424-4372, ext. 0060 (within Alaska, Idaho, Oregon and Washington) The EPA Proposes to Issue NPDES Permit The EPA proposes to issue an NPDES permit for the facility referenced above. The draft permit places conditions on the discharge of pollutants from the hatchery to waters of the United States. In order to ensure protection of water quality and human health, the permit places limits on the types and amounts of pollutants that can be discharged from the facility. This Fact Sheet includes: ▪ information on public comment, public hearing, and appeal procedures ▪ a listing of proposed effluent limitations and other conditions for the hatchery ▪ a map and description of the discharge location ▪ technical material supporting the conditions in the permit Public Comment Persons wishing to comment on, or request a Public Hearing for the draft permit for this facility may do so in writing by the expiration date of the Public Comment period. A request for a Public 1 Fact Sheet Tamgas Creek Hatchery Permit No. AK0028525 Hearing must state the nature of the issues to be raised as well as the requester’s name, address and telephone number.
    [Show full text]
  • Raceway-Based Production of Microalgae for Possible Use in Making Biodiesel
    Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. Raceway-based production of microalgae for possible use in making biodiesel A thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biotechnology at Massey University, Palmerston North, New Zealand Sadia Tahir 2014 Abstract Oils from microalgae are of interest as a potential feedstock for producing renewable transport fuels including gasoline, diesel, biodiesel and jet fuel. For producing feedstock oils, an alga must be capable of being grown easily in readily available seawater and have a high productivity of biomass and oil. This study explored the biomass and lipid production potential of the microalga Chlorella vulgaris in seawater media, as a potential producer of feedstock oils. The alga was grown photoautotrophically under various conditions in 2 L Duran bottles and a pilot scale (138 L) raceway system. Initially, eight species of microalgae of different classes were assessed under nutrient sufficient growth conditions for the production of biomass and lipids in 2 L Duran bottles. Two of the promising species (C. vulgaris and Nannochloropsis salina) were then further evaluated extensively under various conditions (i.e. salinity stress, different levels of nitrogen in growth media, continuous light and light-dark cycling). Based on these assessments C. vulgaris stood out as the best alga for further detailed study. C. vulgaris was evaluated for biomass production and lipid production.
    [Show full text]
  • DFG Hatchery EIR-EIS
    Appendix A Hatchery Operations Appendix A Hatchery Operations This appendix contains site descriptions and operational details for each of the California Department of Fish and Game’s (DFG’s) 14 trout hatchery facilities and 10 salmon and steelhead hatchery facilities. As described in Chapter 2 of this environmental impact report/environmental impact statement (EIR/EIS), hatchery facilities generally fall into one of four categories: brood stock hatcheries, production hatcheries, rearing annexes, and planting bases. A brood stock hatchery provides facilities to rear, maintain, and harvest adult fish for eggs and milt. A production hatchery receives eggs from brood stock hatcheries, incubates the eggs until the fish hatch, and transfers the fry to raceways or ponds for the rearing process. Rearing annexes receive, feed, and rear the fish while monitoring for disease. Planting bases typically receive fish that are of an appropriate size for stocking, and acclimate them before transferring the fish to stocking locations. Salmon and steelhead hatchery facilities are described as either mitigation or enhancement facilities, with some serving both purposes. Mitigation hatcheries were first constructed to offset the loss of anadromous fish habitat due to dam construction. Enhancement hatcheries produce salmon or steelhead to augment fish populations for harvest. Sources of Information The key sources of data and information used in the preparation of this appendix are: z 5­Year Hatchery Facility Infrastructure Plan (Draft) (California Department
    [Show full text]
  • Compliance Guide for the Concentrated Aquatic Animal Production Point Source Category
    Compliance Guide for the Concentrated Aquatic Animal Production Point Source Category United States Environmental Protection Agency Office of Water Washington, DC 20460 (4303T) EPA-821-B-05-001 March 2006 Compliance Guide for the Concentrated Aquatic Animal Production Point Source Category Engineering and Analysis Division Office of Science and Technology U.S. Environmental Protection Agency Washington, DC 20460 March 2006 Acknowledgments The Engineering and Analysis Division, Office of Science and Technology has prepared this compliance guidance and approved it for publication. Tetra Tech, Inc., Contract 68- C-99-263, supported the preparation of the guidance under the direction and review of the Office of Science and Technology. Technical experts in the concentrated aquatic animal production (CAAP) industry prepared the document Best Management Practices for Flow-Through, Net-Pen, Recirculating, and Pond Aquaculture Systems by Tucker, C., S. Belle, C. Boyd, G. Fornshell, J. Hargreaves, S. LaPatra, S. Summerfelt, and P. Zajicek (2003). It provided valuable background information for EPA in the development of this compliance guide. Disclaimer The discussion in this document is intended solely as guidance. The statutory provisions and regulations of the U.S. Environmental Protection Agency (EPA) described in this document contain legally binding requirements. This document is not a regulation itself, nor does it change or substitute for those provisions and regulations. Thus, it does not impose legally binding requirements on EPA, States, or the regulated community. This guidance does not confer legal rights or impose legal obligations upon any member of the public. While EPA has made every effort to ensure the accuracy of the discussion in this guidance, the obligations of the regulated community are determined by statutes, regulations, or other legally binding requirements.
    [Show full text]
  • Application of Computational Fluid Dynamics to Raceways Combining Paddlewheel and CO2 Spargers to Enhance Microalgae Growth
    Journal of Bioscience and Bioengineering VOL. 129 No. 1, 93e98, 2020 www.elsevier.com/locate/jbiosc Application of computational fluid dynamics to raceways combining paddlewheel and CO2 spargers to enhance microalgae growth Adi Kusmayadi,1 George P. Philippidis,2 and Hong-Wei Yen1,2,* Department of Chemical and Material Engineering, Tunghai University, No. 1727, Sec. 4, Taiwan Boulevard, Xitun District, Taichung 40704, Taiwan1 and Patel College of Global Sustainability, University of South Florida, 4202 E. Fowler Avenue, CGS101, Tampa, FL 33620, USA2 Received 16 May 2019; accepted 17 June 2019 Available online 19 July 2019 The present study investigated the effect of light intensity and mixing on microalgae growth in a raceway by comparing the performance of a paddlewheel to a combination of paddlewheel and CO2 spargers in a 20 L raceway. The increase of light intensity was known to be able to increase the microalgal growth rate. Increasing paddlewheel rotation speed from 13 to 30 rpm enhanced C. vulgaris growth by enhancing culture mixing. Simulation results using compu- tational fluid dynamics (CFD) indicated that both the turnaround areas of the raceway and the area opposite the pad- dlewheel experienced very low flow velocities (dead zones) of less than 0.1 m/min, which could cause cell settling and slow down growth. The simulated CFD velocity distribution in the raceway was validated by actual velocity measure- ments. The installation of CO2 spargers in the dead zones greatly increased flow velocity. The increase of paddlewheel rotation speed reduced the dead zones and hence increased algal biomass production. By complementing the raceway paddlewheel with spargers providing CO2 at 30 mL/min, we achieved a dry cell weight of 5.2 ± 0.2 g/L, which was about 2.6 times that obtained without CO2 sparging.
    [Show full text]