The authors would like to acknowledge Aspen Walker at the University of Pennsylvania for her assistance in reactor maintenance and sample collection.

1. Reactor Assembly
<ol>
	<li>Arrange the reactor components according to the schematic in Figure 1.
	<ol>
		<li>Place the reactor (R) on a mixing plate, add a stir bar to the reactor. Place the recycle tank (RT) beside the stir plate and reactor so that the effluent (top) port of the tank is directed towards the edge of the lab bench.</li>
		<li>Place the waste container (W) underneath the effluent (top) port of the recycle tank (RT). Place the feed tank (FT) next to the recycle tank (RT). 
		Not...

<ol>
	<li>Sales, C. M., Shieh, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+an+aerobic/anaerobic+hybrid+bioreactor+under+the+nitrogen+deficient+and+low+F/M+conditions.">Performance of an aerobic/anaerobic hybrid bioreactor under the nitrogen deficient and low F/M conditions.</a> Water Res. 40 (7), 1442-1448 (2006).</li><li>Nootong, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Performance and kinetic evaluations of a novel bioreactor system in the low-oxygen/low-fluid shear reaction environments. , 3225514 (2006).</li><li>Nootong, K., Shieh, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+an+upflow+bioreactor+system+for+nitrogen+removal+via+autotrophic+nitrification+and+denitrification.">Analysis of an upflow bioreactor system for nitrogen removal via autotrophic nitrification and denitrification.</a> Bioresour Technol. 99 (14), 6292-6298 (2008).</li><li>Ramanathan, G., Sales, C. M., Shieh, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+autotrophic+denitrification+and+nitrification+in+a+low-oxygen+reaction+environment.">Simultaneous autotrophic denitrification and nitrification in a low-oxygen reaction environment.</a> Water Sci Technol. 70 (4), 729-735 (2014).</li><li>Rittmann, B. E., McCarty, P. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Environmental Biotechnology: Principles and Applications. , (2001).</li><li>Tchobanoglous, G., Burton, F. L., Stensel, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Wastewater Engineering: Treatment and Reuse. , (2002).</li><li>Palm, J. C., Jenkins, D., Parker, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+between+Organic+Loading,+Dissolved-Oxygen+Concentration+and+Sludge+Settleability+in+the+Completely-Mixed+Activated-Sludge+Process.">Relationship between Organic Loading, Dissolved-Oxygen Concentration and Sludge Settleability in the Completely-Mixed Activated-Sludge Process.</a> Journal Water Pollution Control Federation. 52 (10), 2484-2506 (1980).</li><li>Jenkins, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+a+Comprehensive+Model+of+Activated-Sludge+Bulking+and+Foaming.">Towards a Comprehensive Model of Activated-Sludge Bulking and Foaming.</a> Water Science and Technology. 25 (6), 215-230 (1992).</li><li>Shieh, W., Keenan, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+5+Advances+in+Biochemical+Engineering/Biotechnology.">Ch. 5 Advances in Biochemical Engineering/Biotechnology.</a> Bioproducts. 33, 131-169 (1986).</li><li>Shieh, W. K., Li, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+and+Kinetics+of+Aerated+Fluidized-Bed+Biofilm+Reactor.">Performance and Kinetics of Aerated Fluidized-Bed Biofilm Reactor.</a> Journal of Environmental Engineering-Asce. 115 (1), 65-79 (1989).</li><li>Alvarez-Vazquez, H., Jefferson, B., Judd, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane+bioreactors+vs+conventional+biological+treatment+of+landfill+leachate:+a+brief+review.">Membrane bioreactors vs conventional biological treatment of landfill leachate: a brief review.</a> Journal of Chemical Technology &amp; Biotechnology. 79 (10), 1043-1049 (2004).</li><li>Fenu, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activated+sludge+model+(ASM)+based+modelling+of+membrane+bioreactor+(MBR)+processes:+a+critical+review+with+special+regard+to+MBR+specificities.">Activated sludge model (ASM) based modelling of membrane bioreactor (MBR) processes: a critical review with special regard to MBR specificities.</a> Water Res. 44 (15), 4272-4294 (2010).</li><li>Liu, Y., Tay, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+essential+role+of+hydrodynamic+shear+force+in+the+formation+of+biofilm+and+granular+sludge.">The essential role of hydrodynamic shear force in the formation of biofilm and granular sludge.</a> Water Res. 36 (7), 1653-1665 (2002).</li><li>Chudoba, J., Grau, P., Ottov&#225;, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+activated-sludge+filamentous+bulking-II.+Selection+of+microorganisms+by+means+of+a+selector.">Control of activated-sludge filamentous bulking-II. Selection of microorganisms by means of a selector.</a> Water Research. 7 (10), 1389-1406 (1973).</li><li>Christenson, L., Sims, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+and+harvesting+of+microalgae+for+wastewater+treatment,+biofuels,+and+bioproducts.">Production and harvesting of microalgae for wastewater treatment, biofuels, and bioproducts.</a> Biotechnol Adv. 29 (6), 686-702 (2011).</li><li>Henderson, R., Parsons, S. A., Jefferson, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+algal+properties+and+pre-oxidation+on+solid-liquid+separation+of+algae.">The impact of algal properties and pre-oxidation on solid-liquid separation of algae.</a> Water Res. 42 (8-9), 8-9 (2008).</li><li>Jackson, P. E., Meyers, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Encyclopedia of Analytical Chemistry. , (2000).</li><li>Wilkinson, G. N., Rogers, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Symbolic+descriptions+of+factorial+models+for+analysis+of+variance.">Symbolic descriptions of factorial models for analysis of variance.</a> Applied Statistics. 22, 392-399 (1973).</li><li>Chambers, J. M., Chambers, J. M., Hastie, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+4.">Ch. 4.</a> Statistical Models in S. , (1992).</li><li>R Core Team. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> R: A Language and Environment for Statistical Computing. , (2015).</li><li>Ramanathan, G., Sales, C. M., Shieh, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apendix:Simultaneous+autotrophic+denitrification+and+nitrification+in+a+low-oxygen+reaction+environment.">Apendix:Simultaneous autotrophic denitrification and nitrification in a low-oxygen reaction environment.</a> Water Science &amp; Technology. 70 (4), 729-735 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Wastewater Management Fact Sheet - Energy Conservation. 832F06024, 1-7 (2006).</li><li>Curtis, T. P., Mitchell, R., Gu, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch+13.">Ch 13.</a> Environmental Biotechnology. , (2010).</li><li>Asada, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=THE+WATER-WATER+CYCLE+IN+CHLOROPLASTS:+Scavenging+of+Active+Oxygens+and+Dissipation+of+Excess+Photons.">THE WATER-WATER CYCLE IN CHLOROPLASTS: Scavenging of Active Oxygens and Dissipation of Excess Photons.</a> Annu Rev Plant Physiol Plant Mol Biol. 50, 601-639 (1999).</li><li>Mullineaux, P., Karpinski, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signal+transduction+in+response+to+excess+light:+getting+out+of+the+chloroplast.">Signal transduction in response to excess light: getting out of the chloroplast.</a> Curr Opin Plant Biol. 5 (1), 43-48 (2002).</li><li>Mallick, N., Mohn, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactive+oxygen+species:+response+of+algal+cells.">Reactive oxygen species: response of algal cells.</a> Journal of Plant Physiology. 157 (2), 183-193 (2000).</li><li>Fridovich, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxygen+toxicity:+a+radical+explanation.">Oxygen toxicity: a radical explanation.</a> J Exp Biol. 201 ((Pt 8)), 1203-1209 (1998).</li><li>Doyle, S. M., Diamond, M., McCabe, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chloroplast+and+reactive+oxygen+species+involvement+in+apoptotic-like+programmed+cell+death+in+Arabidopsis+suspension+cultures.">Chloroplast and reactive oxygen species involvement in apoptotic-like programmed cell death in Arabidopsis suspension cultures.</a> J Exp Bot. 61 (2), 473-482 (2010).</li><li>Eisma, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suspended-matter+particle+size+in+some+West-European+estuaries;+part+II:+A+review+on+floc+formation+and+break-up.">Suspended-matter particle size in some West-European estuaries; part II: A review on floc formation and break-up.</a> Netherlands Journal of Sea Research. 28 (3), 215-220 (1991).</li><li>Thomas, D. N., Judd, S. J., Fawcett, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flocculation+modelling:+A+review.">Flocculation modelling: A review.</a> Water Research. 33 (7), 1579-1592 (1999).</li><li>Harris, R. H., Mitchell, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+polymers+in+microbial+aggregation.">The role of polymers in microbial aggregation.</a> Annu Rev Microbiol. 27, 27-50 (1973).</li><li>Raszka, A., Chorvatova, M., Wanner, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+and+significance+of+extracellular+polymers+in+activated+sludge.">The role and significance of extracellular polymers in activated sludge.</a> Part I: Literature review. Acta Hydrochimica Et Hydrobiologica. 34 (5), 411-424 (2006).</li><li>Lakaniemi, A. M., Intihar, V. M., Tuovinen, O. H., Puhakka, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+Dunaliella+tertiolecta+and+associated+bacteria+in+photobioreactors.">Growth of Dunaliella tertiolecta and associated bacteria in photobioreactors.</a> J Ind Microbiol Biotechnol. 39 (9), 1357-1365 (2012).</li><li>Lakaniemi, A. M., Intihar, V. M., Tuovinen, O. H., Puhakka, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+Chlorella+vulgaris+and+associated+bacteria+in+photobioreactors.">Growth of Chlorella vulgaris and associated bacteria in photobioreactors.</a> Microb Biotechnol. 5 (1), 69-78 (2012).</li><li>Natrah, F. M. I., Bossier, P., Sorgeloos, P., Yusoff, F. M., Defoirdt, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Significance+of+microalgal-bacterial+interactions+for+aquaculture.">Significance of microalgal-bacterial interactions for aquaculture.</a> Reviews in Aquaculture. 6 (1), 48-61 (2014).</li><li>Dittami, S. M., Eveillard, D., Tonon, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+metabolic+approach+to+study+algal-bacterial+interactions+in+changing+environments.">A metabolic approach to study algal-bacterial interactions in changing environments.</a> Mol Ecol. 23 (7), 1656-1660 (2014).</li><li>Watanabe, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Symbiotic+association+in+Chlorella+culture.">Symbiotic association in Chlorella culture.</a> FEMS Microbiol Ecol. 51 (2), 187-196 (2005).</li><li>Burke, C., Thomas, T., Lewis, M., Steinberg, P., Kjelleberg, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Composition,+uniqueness+and+variability+of+the+epiphytic+bacterial+community+of+the+green+alga+Ulva+australis.">Composition, uniqueness and variability of the epiphytic bacterial community of the green alga Ulva australis.</a> ISME J. 5 (4), 590-600 (2011).</li><li>Krohn-Molt, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metagenome+survey+of+a+multispecies+and+alga-associated+biofilm+revealed+key+elements+of+bacterial-algal+interactions+in+photobioreactors.">Metagenome survey of a multispecies and alga-associated biofilm revealed key elements of bacterial-algal interactions in photobioreactors.</a> Appl Environ Microbiol. 79 (20), 6196-6206 (2013).</li><li>Cooper, E. D., Bentlage, B., Gibbons, T. R., Bachvaroff, T. R., Delwiche, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metatranscriptome+profiling+of+a+harmful+algal+bloom.">Metatranscriptome profiling of a harmful algal bloom.</a> Harmful Algae. 37, 75-83 (2014).</li></ol>

The authors have nothing to disclose and declare that they have no competing financial interests.

This section will start with a discussion of protocol variations needed to address possible operational issues as well as using different microbial communities. The strengths of this reactor design will be discussed, including the ability to govern control of oxygen flux and the formation of high density flocs within the reactor. Current challenges and possible avenues of investigation will also be mentioned.
Protocol nuances and variations 
The operation of HDBRs for cultivation...

Municipal wastewater is commonly treated with activated sludge processes in order to reduce the suspended solids (SS), biological oxygen demand (BOD), organic and inorganic nitrogen, and phosphorous content5,6. The activated sludge process, a means of secondary wastewater treatment, entails the oxidation of organic carbon in an aeration tank filled with a mixed liquor of incoming wastewater and recycled heterotrophic microorganism (commonly referred to as activated sludge)5-7. The mixed liquor then enters a relatively large clarifier (settling tank) where the sludge settles for easier collection, to either be disposed or recycled back to the aeration tank, while the clarified, treated wastewater can continue to tertiary treatment or disinfection before being released into receiving waters5-7. Efficient separation of the treated wastewater and solids (sludge) in the secondary clarifier is essential for the proper function of a wastewater treatment system, as any activated sludge continuing beyond the clarifiers will increase the BOD and SS in the effluent 5-8.
A number of alternative biological processes exist for secondary treatment of wastewater, which reduce or eliminate the need for large clarifying tanks, including attached-growth (biofilm) reactors, membrane bioreactors (MBRs), and granular sludge reactors. In biofilm reactors, the formation of biofilms, in which microorganisms naturally aggregate and attach as a layer on a solid surface, allows for biomass retention and accumulation without the need for a clarifying tank. Biofilm reactors can be classified into three types: packed bed reactors, fluidized bed reactors, and rotating biological contactors. Packed bed reactors, such as a trickling filters and biological towers, utilize a stationary solid growth surface5,6. Fluidized bed reactors (FBRs) depend on the attachment of microorganisms to particles, such as sand, granular activated carbon (GAC), or glass beads, which are kept in suspension by a high upward flow rate9,10. Rotating biological reactors depend on biofilms formed on media attached to a rotating shaft allowing the biofilm to be alternately exposed to air and the liquid being treated5,6. MBRs use membrane filtration units, either within the bioreactor (submerged configuration) or externally via recirculation (side-stream configuration)5,11. The membranes serve to achieve good separation of biomass and solid particles from the treated liquid11,12. Granular sludge reactors are upflow reactors in which the formation of extremely dense and well-settling granules of microorganisms occurs when they are exposed to high superficial air upflow velocities13.
As another alternative to the activated sludge process, a novel upflow reactor system, now called a high density bioreactor (HDBR), was designed and built by Sales and Shieh (2006) to study COD removal by activated sludge from synthetic waste streams in low F/M conditions that are known to cause the formation of poor settling sludge (i.e., bulking sludge)1,7,14. The HDBR system utilized modified fluidized bed reactors that typically consist of an upflow reactor and an external recycle tank. Fluidized bed reactors are typically operated with recycle stream flow rates high enough to keep the biofilm growth substratum suspended but low enough so that the biofilm-covered substrate is retained. Unlike fluidized bed reactors, the HDBR described in Sales and Shieh (2006) used relatively low recycle stream flow rates which, along with external aeration, prevented disruption of the biomass zone formed within the reactor1. Subsequent studies have demonstrated this reactor design&#39;s ability to successfully treat a range of nitrogen fluxes using nitrifying/denitrifying bacteria3,4. In all studies the formation of a stable, dense biomass zone within the HDBR eliminated the need for an external flocculation/sedimentation process1-4.
As we report here, the use of the HDBR to grow dense cultures has also been tested in a photobioreactor (PBR) configuration for the cultivation of algae. We discuss the benefits and drawbacks of this novel reactor system for algal cultivation and its potential for overcoming a large hurdle in the commercialization of algal biofuels associated with biomass harvesting (i.e., good solid-liquid separation15,16). The following protocol outlines the steps needed to assemble, startup, sample from, and maintain an HDBR with algae as the microbial community of interest. Variations in the startup and operation protocol of heterotrophic and nitrifying/denitrifying cultures will also be mentioned. Lastly, general advantages, disadvantages, and unknowns of this novel reactor design will be highlighted.

<table border="0" cellpadding="0" cellspacing="0" width="686">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Aeration stone</td>
			<td style="width:96px;">Alita</td>
			<td style="width:119px;">AS-3015C</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Aerator</td>
			<td style="width:96px;">Top Fin</td>
			<td style="width:119px;">Air-1000</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Ammonium chloride</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">A9434</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Anion analysis column</td>
			<td style="width:96px;">Shodex</td>
			<td style="width:119px;">IC SI-52 4E</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:213px;">Beaker (600 mL)</td>
			<td style="width:96px;">Corning Pyrex</td>
			<td style="width:119px;">1000-600</td>
			<td style="width:259px;">Used as mixing vessel (MV). Addition of hose barbs at the bottom and 500 mL levels. Outside diameter of hose barbs 3/8&#34;.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Calcium chloride</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">C5670</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Cation analysis column</td>
			<td style="width:96px;">Shodex</td>
			<td style="width:119px;">IC YS-50</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Cobalt chloride hexahydrate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">C8661</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Copper chloride</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">222011</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Ferric chloride</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">157740</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:213px;">Filter (vacuum)</td>
			<td style="width:96px;">Fisherbrand</td>
			<td style="width:119px;">09-719-2E</td>
			<td style="width:259px;">0.45 um membrane filter, MCE, 47 mm diameter</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:213px;">Graduated cylinder (1000 mL)</td>
			<td style="width:96px;">Corning Pyrex</td>
			<td style="width:119px;">3025-1L</td>
			<td style="width:259px;">Used as reactor vessel (R). Addition of hose barbs at bottom, 500 mL, and 1 L levels. Outside diameter of hose barbs 3/8&#34;.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">HPLC/IC</td>
			<td style="width:96px;">Shimadzu</td>
			<td style="width:119px;">Prominence</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Magnesium sulfate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">M2643</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:213px;">Masterflex L/S variable speed drive</td>
			<td style="width:96px;">Masterflex</td>
			<td style="width:119px;">07553-50</td>
			<td style="width:259px;">Drive for recycle and feed pumps (2 needed)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Nickel chloride hexahydrate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">N6136</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Potassium nitrate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">P8291</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:213px;">(Monobasic) Potassium phosphate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">P5655</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Pump head</td>
			<td style="width:96px;">Masterflex</td>
			<td style="width:119px;">07018-20</td>
			<td style="width:259px;">Recycle pump head</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Pump head</td>
			<td style="width:96px;">Masterflex</td>
			<td style="width:119px;">07013-20</td>
			<td style="width:259px;">Feed pump head</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Pump tubing</td>
			<td style="width:96px;">Masterflex</td>
			<td style="width:119px;">6404-18</td>
			<td style="width:259px;">Recycle pump tubing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Pump tubing</td>
			<td style="width:96px;">Masterflex</td>
			<td style="width:119px;">6404-13</td>
			<td style="width:259px;">Feed pump tubing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Sodium bicarbonate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">S5761</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Zinc sulfate heptahydrate</td>
			<td style="width:96px;">Sigma Aldrich</td>
			<td style="width:119px;">Z0251</td>
			<td style="width:259px;"></td>
		</tr>
	</tbody>
</table>

a novel bioreactor for high density cultivation of diverse microbial communities

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past studies have evaluated the performance of the reactor for the removal of COD1 and nitrogen species2-4 by heterotrophic and chemoautotrophic bacteria, respectively. The HDBR design eliminates the requirement for external flocculation/sedimentation processes while still yielding effluent containing low suspended solids. In this study, the HDBR is applied as a photobioreactor (PBR) in order to characterize the nitrogen removal characteristics of an algae-based photosynthetic microbial community. As previously reported for this HDBR design, a stable biomass zone was established with a clear delineation between the biologically active portion of the reactor and the recycling reactor fluid, which resulted in a low suspended solid effluent. The algal community in the HDBR was observed to remove 18.4% of total nitrogen species in the influent. Varying NH4+ and NO3- concentrations in the feed did not have an effect on NH4+ removal (n=44, p=0.993 and n=44, p=0.610 respectively) while NH4+ feed concentration was found to be negatively related with NO3- removal (n=44, p=0.000) and NO3- feed concentration was found to be positively correlated with NO3- removal (n=44, p=0.000). Consistent removal of NH4+, combined with the accumulation of oxidized nitrogen species at high NH4+ fluxes indicates the presence of ammonia- and nitrite-oxidizing bacteria within the microbial community.

The HDBR was used to cultivate algae over several ratios of influent ammonia and nitrate concentrations, while maintaining a total nitrogen content in the feed at 40 mg &#8211;N L-1. Influent and effluent samples were taken daily; biomass density samples were taken at the beginning and end of each condition. The reactor took on average 3-5 days to reach steady state equilibrium after conditions were changed. Over a wide range of influent conditions a distinct biomass zone was established, as observed previous ...

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A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Here, the HDBR is successfully applied in a photobioreactor (PBR) configuration for the study of nitrogen metabolism by a mixed high density algal community.

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past ...

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Research

JoVE Journal

Bioengineering

16.7K vistas.  Drexel University. A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Here, the HDBR is successfully applied in a photobioreactor (PBR) configuration for the study of nitrogen metabolism by a mixed high density algal community.