anaerobic membrane bioreactor technology for solid waste stabilization

346 Pages·2009·7.86 MB·English

ANAEROBIC MEMBRANE BIOREACTOR
TECHNOLOGY FOR SOLID WASTE
STABILIZATION
By
Antoine Prandota Trzcinski
A thesis submitted for the degree of Doctor of Philosophy and for the Diploma of Imperial
College
Department of Chemical Engineering and Chemical technology
Imperial College London
London SW7 2AZ
May 2009
It is declared that the work presented in the thesis is the candidate’s own.
Signature of Candidate
1
ABSTRACT
In this study, a simulated Organic Fraction of Municipal Solid Waste (OFMSW) was treated in
an anaerobic two-stage membrane process. The OFMSW feedstock was fed to a ten litre hy-
drolytic reactor (HR) where solid and liquid fractions were separated by a coarse mesh, while
the leachate was fed to a three litre submerged anaerobic membrane bioreactor (SAMBR) with
in-situ membrane cleaning by biogas sparging beneath a flat sheet Kubota membrane. The
aim was to develop and optimize this two-stage process where the use of a membrane in both
reactors to uncouple the Solid and Liquid Retention Times (SRT and HRT) would allow us to
improve the current performances obtained with single stage designs. The Denaturing Gradient
Gel Electrophoresis (DGGE) technique was used to monitor the microbial population in the re-
actors and have a better understanding of the archaeal and bacterial distribution in a two-stage
process.
Itwasfoundthatmesheswithporesizesof≤10micronsand≥150micronswereinappropriate
to uncouple the SRT and HRT in the HR. In the former case, the mesh became clogged, while
in the latter case, the large pore size resulted in high levels of suspended solids in the leachate
thatbuiltupintheSAMBR.ThemostimportantparameterforVolatileSolids(VS)removalinthe
HRwastheSRT.MaximumVSremovalsof70-75%couldbeachievedwhentheSRTwasequal
toorgreaterthan50-60days. ThiswasachievedataHRTof9-12daysandanOrganicLoading
Rate (OLR) of 4-5 g VS.l-1.day-1.Increasing the SRT to beyond 100 days did not significantly
increase the VS removal in the HR. However, at an OLR of 10 g VS.l-1.day-1 in the HR the SRT
had to be reduced due to a build up of TS in the HR that impeded the stirring. Below 20 days
SRT,theVSremovalreducedtobetween30and40%. Withkitchenwasteasitsmainsubstrate,
however, an OLR of 10 g VS.l-1.day-1 was achieved with 81% VS removal at 23 days SRT and
1.8 days HRT.
The SAMBR was found to remain stable at an OLR up to 19.8 g COD.l-1.day-1 at a HRT of
0.4 day and at a SRT greater than 300 days, while the COD removal was 95%. However, the
performance at such low HRTs was not sustainable due to membrane flux limitations when
the Mixed Liquor Total Suspended Solids (MLTSS) went beyond 20 g.l-1 due to an increase in
viscosity and inorganics concentration. At 35˚C the SAMBR was found to be stable (SCOD
removal ≥ 95%) at SRTs down to 45 days and at a minimum HRT of 3.9 days. The SAMBR
could achieve 90% COD removal at 22˚C at an OLR of 13.4 g COD.l-1.day-1 and 1.1 days HRT
(SRT = 300 days).
The DGGE technique was used to monitor the archaeal and bacterial diversity and evolution
in the HR and SAMBR with varying SRTs, HRTs, OLRs and temperatures in the biofilm and
in suspension. Overall, it was found that stable operation and high COD removal correlated
with a high bacterial diversity, while at the same time very few species (2-4) were dominant.
Only a few dominant archaeal species were sufficient to keep low VFA concentrations in the
SAMBR at 35˚C, but not at ambient temperatures. It was found that some of the dominant
species in the HR were hydrogenotrophic Archaea such as Methanobacterium formicicum and
Methanobrevibacter while the other dominant species were from the genus Methanosarcina
2
or Methanosaeta. The presence of hydrogenotrophic species in the HR could be fostered by
reinoculating the HR with excess sludge from the SAMBR when the SRT of the SAMBR was
greater than 45 days. Among the bacterial species Ruminococcus flavefaciens, Spirochaeta,
Sphingobacteriales,Hydrogenophaga,Ralstonia,PrevotellaandSmithellawereassociatedwith
good reactor performances.
3
ACKNOWLEDGEMENTS
First of all, I would like to deeply thank my supervisor Professor David Stuckey for his inspiring
and motivating guidance throughout this research. His passion for anaerobic wastewater treat-
ment and his commitment to sustainable development encouraged me to start and go on with
the long and painstaking process of doing a PhD thesis on this subject.
IwouldliketothanktheDepartmentofEnvironment,FoodandRuralAffairs(DEFRA)forfinanc-
ing this project under the Technologies Research and Innovative Fund (TRIF).
I would like to acknowledge all members of the laboratory for interesting discussions both in
group meetings and in more social environments.
Finally, from the depth of my heart, many thanks to Flora, my mother, father and brother for
encouraging me all the way.
4
NOTATIONS
AD Anaerobic Digestion
AF Anaerobic Filter
AOB Ammonia-Oxidising Bacteria
ATA Anaerobic Toxicity Assay
BET Brunauer-Emmett-Teller
BMP Biochemical Methane Potential
BSI British Standard Institution
BVS Biodegradable Volatile Solids
C:N Carbon to Nitrogen Ratio
COD Chemical Oxygen Demand (mg/L)
CP Concentration Polarisation
CSTR Continuously Stirred Tank Reactor
dm dry matter
DO Dissolved Oxygen
EGSB Expanded Granular Sludge Bed
EPS Extracellular Polymeric Substances
EC European Commission
FA Free Ammonia
FF Fixed-Film reactor
FS Flat Sheet
FSS Fixed Suspended Solids
FWC Fresh Water Consumption
FYV Fruits, Yard and Vegetables waste
GAC Granular Activated Carbon
GPR Gas Production Rate
GW Garden Waste
HF Hollow Fibers
HOA Hydrogen-Oxidising Acetotrophs
HOM Hydrogen-Oxidising Methanogens
HR Hydrolytic Reactor
HRT Hydraulic Retention Time
IPW Industrial Potato Waste
k bacterial decay rate constant
d
k Hydrolyis constant
h
K Half-saturation coefficient for substrate utilization
s
KW Kitchen Waste
LB Leach-Bed
LCFA Long-Chain Fatty Acids
LMH Litre.m-2.hr-1
LPM Litre per Minute
MBR Membrane Bioreactor
MBT Mechanical-biological treatment
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MF Microfiltration
MLTSS Mixed Liquor Total Suspended Solids
MLVSS Mixed Liquor Volatile Suspended Solids
MS-OFMSW Mechanically-Sorted Organic Fraction of Municipal Solid Waste
MSW Municipal Solid Waste
MTBE Methyl Tertiary-Butyl Ether
MW Molecular Weight
µ Maximum growth rate
max
NHOA Non-Hydrogen Oxidising Acetotrophs
NOB Nitrite-Oxidising Bacteria
OFMSW Organic Fraction of Municipal Solid Waste
OHPA Obligate Hydrogen Producing Acetogenic bacteria
OLR Organic Loading Rate
PAC Powdered Activated Carbon
PB Packed Bed reactor
PS Primary Sludge
PSD Particle Size Distribution
PW Paper Waste
RPM Revolutions per Minute
ROS Refractory Organic Substances
SAMBR Submerged Anaerobic Membrane Bioreactor
SAMBR-MABR Submerged Anaerobic Membrane Bioreactor - Membrane aerated Bioreactor
SBR Sequencing Batch Reactor
SCOD Soluble Chemical Oxygen Demand
SEBAC Sequential Batch Anaerobic Composting reactor
SEC Size Exclusion Chromatography
SGP Specific Gas Production
SMP Soluble Microbial Products
SMY Specific Methane Yield
SPE Solid Phase Extraction
SRT Solid Retention Time
SS Sidestream
SS-OFMSW Source-Sorted Organic Fraction of Municipal Solid Waste
STP Standard Temperature and Pressure
T Tubular
TMP Transmembrane Pressure
TS Total Solids
TSS Total Suspended Solids
U Specific Substrate utilization rate
UASB Upflow Anaerobic Sludge Blanket
UF Ultrafiltration
VFAs Volatile Fatty Acids
VS Volatile Solids
VSS Volatile Suspended Solids
WAS Waste Activated Sludge
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Contents
1 INTRODUCTION 23
2 LITERATURE REVIEW 26
2.1 ANAEROBIC DIGESTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.1.1 Hydrolytic Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.1.2 Fermentative Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.1.3 Acetogenic Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.1.4 Methanogenic Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.1.5 Protein Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.1.6 Ammonia Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.2 MUNICIPAL SOLID WASTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.2.2 Composition of the Organic Fraction of Municipal Solid Waste . . . . . . . . 34
2.2.3 Biodegradability of the Organic Fraction of Municipal Solid Waste . . . . . . 36
2.2.4 Kinetics of the Anaerobic Digestion of MSW . . . . . . . . . . . . . . . . . . 37
2.3 FACTORS AFFECTING THE AD OF MSW . . . . . . . . . . . . . . . . . . . . . . 39
2.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.3.2 Inoculum/Substrate Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.3.3 Pretreatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.3.4 Particle Size Distribution (PSD) . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3.5 pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3.6 Alkalinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3.7 Solid Retention Time (SRT) . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3.8 Total Solid Content (TS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.3.9 Organic Loading Rate (OLR) . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.3.10 Volatile Fatty Acids Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.3.11 Effect of Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
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CONTENTS CONTENTS
2.3.12 Ammonia Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.3.13 Struvite Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.3.14 Calcium Salts Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.3.15 Nutrient Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
2.3.16 Phase Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.3.17 Recirculation of the Effluent . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.3.18 Stability of the Digestate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.3.19 Solid Waste Anaerobic Processes . . . . . . . . . . . . . . . . . . . . . . . 56
2.4 ANAEROBIC MEMBRANE BIOREACTORS . . . . . . . . . . . . . . . . . . . . . . 58
2.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
2.4.2 Concentration Polarisation . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.4.3 Nominal Pore Size and Flux . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.4.4 Fouling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.4.5 AnaerobicMembraneBioreactorsforHighStrengthWastewaterandLeachate
Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.5 PHYSICO-CHEMICAL TREATMENT OF STABILISED LEACHATE . . . . . . . . . 69
2.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
2.5.2 Activated Carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
2.5.3 Coagulation-Flocculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
2.5.4 Ultrafiltration (UF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.5.5 Ion Exchange Resins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.6 SUMMARY OF LITERATURE REVIEW . . . . . . . . . . . . . . . . . . . . . . . . 73
2.7 OBJECTIVES OF THE STUDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3 MATERIALS AND METHODS 77
3.1 EXPERIMENTAL SETUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.1.1 Hydrolytic Reactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.1.2 Methanogenic Reactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.2 ANALYTICAL METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.2.1 pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.2.2 Oxido-Reduction Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.2.3 Biogas Composition and Production Rate . . . . . . . . . . . . . . . . . . . 79
3.2.4 Volatile Fatty Acids (VFAs) . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.5 Gas Chromatography - Mass Spectrometry (GC-MS). . . . . . . . . . . . . 79
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CONTENTS CONTENTS
3.2.6 Particle Size Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.2.7 Heavy Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.2.8 Ion Chromatography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.2.9 Size Exclusion Chromatography (SEC) . . . . . . . . . . . . . . . . . . . . 82
3.2.10 Scanning Electron Microscope - Energy Dispersive X-ray (SEM-EDX) . . . 82
3.2.11 Surface Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.3 PHYSICO-CHEMICAL METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.3.1 Alkalinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.3.2 Total Solids, Volatile Solids and Fixed Solids . . . . . . . . . . . . . . . . . 83
3.3.3 Total Suspended Solids and Volatile Suspended Solids . . . . . . . . . . . 83
3.3.4 COD Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.3.5 Ammonia Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.3.6 Total Nitrogen Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.3.7 Total Phosphorus Measurement . . . . . . . . . . . . . . . . . . . . . . . . 84
3.3.8 Carbohydrates Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.3.9 Protein Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.3.10 Ultrafiltration Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.3.11 Biochemical Methane Potential Test . . . . . . . . . . . . . . . . . . . . . . 86
3.3.12 Microbial Respiration Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.3.13 Adsorption Isotherms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.3.14 Adsorption Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.4 MOLECULAR BIOLOGY METHODS: Denaturing Gel Gradient Electrophoresis
(DGGE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.5 FEEDSTOCK COMPOSITION AND PROPERTIES . . . . . . . . . . . . . . . . . . 91
3.5.1 Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.5.2 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4 EFFECT OF ACETIC ACID ON THE CHEMICAL HYDROLYSIS OF THE OFMSW 98
4.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.2 EXPERIMENTAL AND ANALYTICAL DETAILS . . . . . . . . . . . . . . . . . . . . 100
4.2.1 Chemical hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4.2.2 Enzymatic hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4.3 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.3.1 Chemical hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
9