Microbial decontamination of urea formaldehyde bonded medium density fiberboard Approved

105 Pages·2016·2.27 MB·English

by  Roudi Bachar

Microbial decontamination of urea formaldehyde bonded medium density fiberboard
By
Roudi Bachar
A thesis submitted to Saint Mary’s University, Halifax, Nova Scotia
In partial fulfillment of the requirements for
The degree of Master of Science in Applied Science

April 2016, Halifax, Nova Scotia
© Roudi Bachar, 2016

Approved: Dr. Zhongmin Dong
[Supervisor]

Approved: Dr. Gavin Kernaghan
[Supervisor]

Approved: Dr. Madine VanderPlaat

[Committee Member]

Approved: Dr. Lei Liu
[External Reader]

Date: April 15, 2016
Table of Contents
Abstract ........................................................................................................................................... iv
Acknowledgements .......................................................................................................................... v
Abbreviations .................................................................................................................................. vi
List of Table and Figures ................................................................................................................ vii
1.0 Introduction ............................................................................................................................... 1
1.1 Current waste disposal and recycling programs ........................................................................ 1
1.2 Municipal solid waste (MSW) characterization ......................................................................... 3
1.3 Engineered wood products (EWP) ............................................................................................. 4
1.4 Urea-formaldehyde (UF) ............................................................................................................ 5
1.5 MDF and UF environmental impact ........................................................................................... 7
1.6 UF metabolic pathways .............................................................................................................. 9
1.6.1 Anaerobic pathways ............................................................................................................... 9
1.6.2 Aerobic pathways .................................................................................................................. 10
1.7 Anaerobic Digestion ................................................................................................................. 11
1.7.1 Anaerobic digestion background .......................................................................................... 11
1.7.2 Four stages of anaerobic digestion ....................................................................................... 12
1.7.2.1 Hydrolysis ........................................................................................................................... 12
1.7.2.2 Acidogenesis and acetogenesis.......................................................................................... 13
1.7.2.3 Methanogenesis ................................................................................................................. 13
1.7.3 Anaerobic digestion reactor temperature conditions and resilience ................................... 14
1.7.4 Batch and continuous reactors ............................................................................................. 15
1.7.5 Mixed-acid fermentation ...................................................................................................... 16
1.7.6 Hydrolysis rates ..................................................................................................................... 17
1.7.6.1 Pre-treatments for increased hydrolysis rates .................................................................. 17
1.8 Experimental design ................................................................................................................. 19
1.8.1 Anaerobic digestion inoculum .............................................................................................. 19
1.8.2 Fungal isolates ....................................................................................................................... 20
1.9 Objectives ................................................................................................................................. 22
2.0 Material and Methods ............................................................................................................. 24
2.1 Material and methods for anaerobic digestion ....................................................................... 24
i
2.1.1 MDF pre-treatment ............................................................................................................... 24
2.1.2 Inoculum Type ....................................................................................................................... 24
2.1.3 Reactor hardware and environmental conditions ................................................................ 25
2.1.4 Batch reactor setup and digestion period ............................................................................ 25
2.1.5 Sample collection and non-specific preparation .................................................................. 26
2.1.6 Purpald formaldehyde analysis ............................................................................................. 26
2.1.7 VFA analysis........................................................................................................................... 27
2.1.8 HPLC Analysis ........................................................................................................................ 28
2.1.8.2 HPLC analysis pre-treatment ............................................................................................. 29
2.1.8.3 HPLC analysis reactor design ............................................................................................. 30
2.2 Material and methods for aerobic fungal degradation of UF .................................................. 35
2.2.1 Fungal isolation and cultivation ............................................................................................ 35
2.2.2 FA degradation and optimal temperature test ..................................................................... 35
2.2.3 Formaldehyde and pH analysis ............................................................................................. 36
2.2.4 Mathematical analysis .......................................................................................................... 37
2.2.4.1 Statistical analysis .............................................................................................................. 37
2.2.4.2 Gas production calculation ................................................................................................ 38
3.0 Results ...................................................................................................................................... 39
3.1 Results for anaerobic digestion experiment ............................................................................ 39
3.1.1 Identification of optimal inoculum source ............................................................................ 39
3.1.2 Optimal inoculum sources FA concentrations ...................................................................... 39
3.1.3 Optimal inoculum sources gas production ........................................................................... 40
3.2 Determining optimal abiotic conditions for anaerobic digestion results ................................ 45
3.2.1 Mesophilic and thermophilic reactors FA degradation ability .............................................. 45
3.2.2 Fungal growth in MDF+ / FA+ controls ................................................................................. 45
3.2.3 UF hydrolysis rates ................................................................................................................ 46
3.2.4 Mesophilic and thermophilic reactors gas production ......................................................... 47
3.2.5 VFA post digestion data ........................................................................................................ 48
3.2.5.1 Quantitative data of identified VFAs ................................................................................. 48
3.2.5.2 Presence of unidentified VFAs and un-hydrolyzed UF ....................................................... 49
3.2.6 HPLC analysis of mesophilic DCM reactors ........................................................................... 49
3.3 Fungal growth temperature test results .................................................................................. 64
ii
3.3.1 Effect of temperature on fungal FA degradation ability ....................................................... 64
3.3.2 Fungal growth FA degradation pH and visual observation results ....................................... 65
3.4 Differences between final FA concentration in anaerobic and aerobic treatments ............... 69
4.0 Discussion ................................................................................................................................. 71
4.1 Anaerobic digestion ................................................................................................................. 71
4.1.1 Selecting the most efficient and economically viable inoculum for anaerobic digestion .... 71
4.1.2 Optimal abiotic conditions for anaerobic digestion.............................................................. 72
4.1.2.1 Optimal temperature for FA degradation .......................................................................... 73
4.1.2.2 Pre-treatment usage and remaining UF resin .................................................................... 74
4.1.2.3 Method discrimination for detected formaldehyde (HPLC, Purpald, GC-FID) ................... 76
4.2 P. variotii metabolization of UF resin ....................................................................................... 77
4.2.1 P. variotii total breakdown for FA ......................................................................................... 77
4.2.2 P. variotii temperature and pH variation .............................................................................. 78
4.2.3 Limitations of P. variotii degradation of UF resins ................................................................ 79
4.3 Conclusion ................................................................................................................................ 81
References ..................................................................................................................................... 82

iii
Abstract
Microbial decontamination of urea formaldehyde bonded medium density fiberboard
By Roudi Bachar

Urea-formaldehyde (UF) is a resin commonly used as an adhesive for medium density
fiberboard (MDF). Diverting MDF from Canadian landfills is important to decrease
annual methane emissions. The use of anaerobic digestion and aerobic fungi were
investigated as potential decontamination methods for the decontamination of toxic
UF resins; specifically the formaldehyde (FA) component. For anaerobic digestion batch
reactors with three inoculum types were used; diluted cow manure (DCM) inocula and
decaying sea weed (DSW). FA concentration, gas production, and reactor conditions
were measured. Reactors with 10 g L-1 MDF (1.1 – 1.4 g UF) were used with retention
times of 38 days. Thermophilic (55 °C) reactors with fresh DCM as an inoculum had the
greatest UF decontamination and gas production. Final FA concentration was 5.523 (SD
= 1.516) ppm. GC-FID suggested partial UF resin un-hydrolyzed still in solution. The
aerobic fungus Paecilomyces variotii was tested at various temperatures for its FA
degrading potential. At 40 °C P. variotii could decontaminate autoclaved MDF with FA
concentrations dropping from 400 ppm to 3.970 ppm (SD 3.832) ppm in 7 days, but pH
rapidly increased and fungal death occurred.

April 15, 2016

iv
Acknowledgements
I would like to thank everyone who helped me along the way these past two years.
The faculty and staff in the SMU Biology department have been a huge help in guiding me
throughout my research. All the lab technicians for putting up with me and all my mistakes
specifically. From leaving hot plates on unattended to breaking glassware, you all
supported me through every mistake I made. At SMU in the chemistry department I would
like to thank graduate student and friend Graeme Soper. His help in columns and
analytical chemistry was invaluable. Having a senior graduate student to look up to
brought a lot of relief to me during times of stress. I would like to thank Dr. Gwyneth Jones
for continuously providing us with cow manure on such short notice. I would like to thank
the FSGR at SMU and RRFB Nova Scotia for helping me fund my research. I would like to
thank Dr. Hugh Broders in helping me become a better scientist and a more critical
thinker. Showing me what a true well rounded person looks like. I would like to thank
both of my supervisors Dr. Gavin Kernaghan for helping me become a cleaner scientist in
regards to molecular biology. For teaching me so much with regards to mycology and
opening my eyes to the wonders of the fungal world all around. I would like to thank Dr.
Zhongmin Dong. For the past 4 years you have had faith in me, helping me become the
person I am today. Thank you for all your support in helping me understand my
weaknesses and working on them while exceling at my strengths. For showing me true
kindness and being the foundation for my entire scientific career. Thank you for always
believing in me. And finally I would like to thank my family. My brothers, mother, and
father who have supported me since day one, showing me love and compassion. I hope
one day to become who you believed I could be and repay you all.

v
Abbreviations
2,4-DNPH 2,4-Dinitrophenylhydrazine

AB Anaerobic Bioreactor

AD Anaerobic Digestion

DCM Diluted Cow Manure

DSW Decaying Sea Weed
EWP Engineered Wood Products
FA Formaldehyde

FA-2,4-DNPH Formaldehyde-2,4-Dinitrophenylhydrazine

FCM Frozen Cow Manure

GC-FID Gas Chromatography – Flame Ionization Detector
HPLC High Performance Liquid Chromatography
HTPT High Temperature Pre-Treatment

LTPT Low Temperature Pre-Treatment

MDF Medium Density Fiberboard

UF Urea-Formaldehyde
VFA Volatile Fatty Acid

vi
List of Table and Figures

Figure 1 – Anaerobic digester set up. 28
Table 1 – Organic acids typically found as products of anaerobic fermentation with peak 29
wavelengths.

Table 2 – Bioreactor set up for HPLC analysis optimization. 29

Table 3 – Bioreactor conditions used through anaerobic digestion experiments. 30

Equation 1 - Reactor and water column gas pressure equation. 34
Equation 2 – Actual volume of gas produced in each digester. 34
Figure 2 – Standard curve of Purpald solution used in FA concentration determination 37
Table 4 – FA degradation for three inocula at 40 °C. 38
Figure 3 – FA degradation for three inocula at 40 °C. 39
Figure 4 – Gas production data for optimal inoculum trials. 40
Figure 5 – FA concentration levels in DCM at 40 and 55 °C and their negative controls. 48
Figure 6 – FA concentration levels in DCM at 40 and 55 °C and their positive controls. 49
Figure 7 – FA concentration levels in MDF+ DCM- controls (hydrolysis rates). 50
Figure 8 – Gas production averages from DCM optimization experiment. 51
Figure 9 – VFA levels found in pre-digestion and post-digestion inocula. 53
vii
Figure 10 – GC-FID graph of compounds present in pre-digestion cow manure. 54
Figure 11 – GC-FID graph of compounds present in post-digestation DCM. 55
Table 5 – HPLC analysis of standards and stock solutions including retention times and 56
peak strengths.
Figure 12 – F-2,4-DNPH in DCM sample. 57
Figure 13 – 2,4-DNPH in water solution. 58
Figure 14 – Final FA concentration after seven day metabolization period for three fungi. 62
Table 6 – pH of fungi after seven day period of UF metabolization. 63
Figure 15 – Relationship between FA degradation ability and temperature for three fungi. 64
Figure 16 – One-way ANOVA test of most effective FA degradation treatment groups. 65

viii
This page is intentionally left blank
ix