Engineering Conferences International ECI Digital Archives Wastewater and Biosolids Treatment and Reuse: Proceedings Bridging Modeling and Experimental Studies Spring 6-10-2014 The integrated biohydrogen reactor clarifier system (IBRCS): setup, performance, and application Hesham El-Naggar Western University Follow this and additional works at: http://dc.engconfintl.org/wbtr_i Part of the Environmental Engineering Commons Recommended Citation Hesham El-Naggar, "The integrated biohydrogen reactor clarifier system (IBRCS): setup, performance, and application" in "Wastewater and Biosolids Treatment and Reuse: Bridging Modeling and Experimental Studies", Dr. Domenico Santoro, Trojan Technologies and Western University Eds, ECI Symposium Series, (2014). http://dc.engconfintl.org/wbtr_i/16 This Conference Proceeding is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in Wastewater and Biosolids Treatment and Reuse: Bridging Modeling and Experimental Studies by an authorized administrator of ECI Digital Archives. For more information, please contact [email protected]. The Integrated Biohydrogen Reactor Clarifier System (IBRCS): Setup, Performance, and Application Wastewater & Biosolids Treatment & Reuse: Bridging Modeling & Experimental Studies ECI Conference 8th-14th June 2014 Dr. Hesham El Naggar Department of Civil and Environmental Engineering Renewable Energy Sources : Green energy Hydropower Geothermal Wind Biomass Hydrogen 2 Why Hydrogen? Motivation for recent focus on H2 Attractive fuel : H2O when combusted (Carbonless) Can be produced from all primary energy sources Depletion of oil resources Climate Change concerns : Global Warming 100% pollution-free Highest energy content per unit weight of any known fuel 100% sustainable/renewable 3 Biological Hydrogen Production Biohydrogen production from organic waste addresses: . Soaring energy demand . Water demand/treatment (New Water) . Environmental pollution Microorganisms can produce H2 via photosynthesis or fermentation Fermentation is generally preferred ; technically simpler and doesn’ t need a source of light. 4 Dark Fermentation Organic pollutants are anaerobically converted to methane in two distinct stages: Acidification (VFAs + hydrogen) Methanogenesis (VFAs are converted in to methane gas ) 5 Hybrid (Two-stage) system Separation of the two stages is feasible CH4 + CO2 for hydrogen collection from the first stage . Organic Waste Treated Waste The remaining acidification products mainly volatile fatty acids are Conventional Digester processed in the second stage. CH4 + CO2 Organic Waste T r e a t e d W aste Conventional Digesters H2 + CO2 CH4 + CO2 Organic Waste Volatile Fatty Acids Treated Waste 6 Hydrogen Bioreactor Methane Bioreactor Introduction Continuous Stirred Tank Reactor (CSTR) Biogas (mixture) Substrate Organic acids Biomass Biomass Nutrients Buffer 7 Introduction CSTR Problem HRT : Hydraulic retention Time SRT : Solid Retention Time V : Reactor volume Q : Flow rate XR : Biomass in reactor Biomass Washout 8 IBRCS Setup Integrated Biohydrogen Reactor Clarifier System “IBRCS” Chemical Addition H2 + CO2 for pH adjustment NaHCO3 Influent Effluent V : Reactor volume Q : Influent flow rate CSTR Qe : Effluent flow rate Qw : Waste flow rate Gravity Settler X : Biomass in reactor Biomass Recirculation R Xe : Biomass in effluent Excess Biomass Wastage Xw : Biomass in waste • Hafez et al. 2010 9 General Purpose of the Technology The main purpose of this technology is energy recovery during the treatment of high strength industrial wastewaters, predominantly from : Food and agriculture sector Young landfill leachates from non-hazardous waste disposal sites. Wastes that are generally rich in organics specially carbohydrates, glucose, sucrose and starch. 10 Comparative Assessment - IBRCS Vs. CSTR Operational conditions in the hydrogen producing systems Glucose (g/L) HRT (h) SRT (h) OLR (gCOD/L/d) pH IBRCS -1 2 8 48 ± 3.2 6.5 5.5-6.5 IBRCS -2 8 8 46 ± 4.2 25.7 5.5-6.5 CSTR-1 8 8 8 25.7 5.5-6.5 CSTR-2 20 12 12 42.8 5.5 (controlled) • Hafez et al. 2010 11 Long-Term Performance (a) 12 11 10 9 8 IBRCS-1, 6.5 gCOD/L-d 7 IBRCS-2, 25.7 gCOD/L-d 6 CSTR-1, 25.7 gCOD/L-d 5 CSTR-2, 42.8 gCOD/L-d 4 3 2 H2 Production H2 Rate(L/L-d) 1 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Time (d) (b) 4 3 IBRCS-1, 6.5 gCOD/L-d 2 IBRCS-2, 25.7 gCOD/L-d CSTR-1, 25.7 gCOD/L-d CSTR-2, 42.8 gCOD/L-d H2 Yield (mol/mol) Yield H2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Time (d) Diurnal variation in: a) hydrogen production rate, b) hydrogen yield 12 Summary of Steady State Data Hydrogen Gas Hydrogen Gas Hydrogen Yield % Glucose (%) (L/L/d) (mol/mol) converted IBRCS -1 71 ± 0.9 2.4 ± 0.2 2.8 ± 0.3 99.9 ± 0.1 IBRCS -2 73 ± 2.7 9.6 ± 0.9 2.8 ± 0.3 99.9 ± 0.1 CSTR-1 66 ± 5.3 1.8 ± 0.2 1.0 ± 0.1 50 ± 3.5 CSTR-2 76 ± 3.6 0.55 ± 0.11 0.5 ± 0.1 29 ± 5.7 Note. Values represent average ± standard deviation 13 IBRCS Performance – Glucose Testing Experimental Setup Operational Conditions Chemical Addition H2 + CO2 for pH adjustment HRT = 8 hrs NaHCO3 Glucose conc. = 2 – 64 g/L Effluent Glucose OLR1 - 6 = 6.5 – 206 gCOD/L.d Flow rate = 15 L/d Reactor Working Vol. = 5 L CSTR SRT = 26 – 50 hrs Gravity Settler Biomass Recirculation OLR : Organic Loading Rate Excess Biomass Wastage • Hafez et al. 2010 14 IBRCS Performance – Glucose Testing H2 Yield 15 IBRCS Performance Optimization – Glucose Testing H2 Yield & H2 Production Rate Vs. OLR 16 IBRCS Performance – Corn Syrup Testing Experimental Setup Operational Conditions Chemical Addition H2 + CO2 for pH adjustment NaHCO3 HRT = 8 hrs OLR = 26 – 81 gCOD/L.d Corn Syrup Effluent Flow = 15 L/d Reactor Working Vol. = 5 L SRT = 52.8 – 60 hrs CSTR Gravity Settler Biomass Recirculation Excess Biomass Wastage • Hafez et al. 2010 17 IBRCS Performance – Corn Syrup Testing H2 Yield OLR-1 OLR-2 OLR-3 26 gCOD/L.d 52 gCOD/L.d 81 gCOD/L.d 18 IBRCS Performance Optimization– Corn Syrup Testing H2 Yield & H2 Production Rate Vs. OLR 19 Economical Evaluation 20 Summary of Results The system produces biogas up to 50 m3/m3/d, hydrogen content up to 70%, CO2 content 30%. Hydrogen yield 3.2 mol H2 /mol glucose out of 3.4 theoretical Methane yield approached the theoretical value (390 L CH4/ kgCOD removed), Methane content up to 60%, CO2 content 40%. Overall organic matter removal over 95% • Hafez et al. 2010 21 Application – CO2 Sequestration Applying CO2 Sequestration in Reactor Headspace I II Without KOH With KOH Chemical Addition Operational Conditions (H + CO ) (H ) for pH adjustment 2 2 2 NaHCO3 HRT = 8 hrs Glucose conc. = 8 & 16 g/L Glucose Effluent OLR1&2 = 25.7 & 51.4 gCOD/L.d Flow = 21 L/d Completely Mixed Reactor Working Vol. = 7 L Bioreactor Gravity Settler Stage I: without KOH Biomass Recirculation Stage II: with KOH (pellets Excess Biomass Wastage 22 Application – CO2 Sequestration H2 Content (%) 120 Without KOH 100 100 100 With KOH 80 65±3 60 57±4 40 Hydrogen Hydrogen content (%) 20 0 OLR 1 OLR 2 OLR (g COD/Lreactor.d) 23 Application – CO2 Sequestration H2 Yield (mol H2/molglucose added) 3.5 Without KOH 3.10±0.19 2.96±0.14 3 With KOH /mol /mol 2.50±0.18 2 2.5 2.42±0.15 2 1.5 1 glucoseaddedd) 0.5 Hydrogen Hydrogen yield (mol H 0 OLR 1 OLR 2 51.4 25.7 OLR (g COD/L.d) 24 Application – CO2 Sequestration Buffer & KOH Requirements NaHCO3 added pH controller Feed Total Soln. conc. pH g/L g/d mL/d g/L g/d g/d g NaHCO3/g glucose feed 1 Without KOH 5.2±0.2 3 63 825 168 139 202 1.2 - OLR With KOH 5.2±0.2 3 63 140 168 24 87 0.52 2 Without KOH 5.2±0.2 5 105 1320 168 222 327 1.0 - OLR With KOH 5.2±0.2 5 105 190 168 32 137 0.41 KOH requirement: Theoretical: 117 & 174 g/d Actual: 136 & 196 g/d 25 Application – CO2 Sequestration Microbial Community Analysis H2 Producers Blautia Ruminococcus Ethanoligenens Megasphaera Clostridium Non-H2 Producers Veillonella Faecalibacterium Dialister Sutterella Desulfovibio 26 Conclusions Decoupling of SRT from HRT in biohydrogen production systems validated the promise of using a gravity settler after a CSTR IBRCS decreased biomass washout by maintaining a high biomass retention time IBRCS showed stable performance over a period of 100 days using glucose as a synthetic waste & corn syrup as a real waste Average yields of > 3 mol/molhexose was achieved Headspace CO2 sequestration increased H2 yield by 23% to 3.1 mol/molhexose & decreased buffer consumption CO2 sequestration had a significant impact on the microbial culture 27 28 .