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

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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

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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

CSTR SRT = 52.8 – 60 hrs

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

Effluent Glucose conc. = 8 & 16 g/L Glucose

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