Utilization of ultraviolet-visible spectroscopy and rheology for sludge characterization and monitoring by Jordan Smyth A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Master of Applied Science in Environmental Engineering Department of Civil and Environmental Engineering Ottawa-Carleton Institute for Environmental Engineering Carleton University Ottawa, Ontario © Jordan Smyth, 2018 Abstract Operation of sludge treatment processes mainly relies on manual control, which is far from ideal. There is a need for new approaches to optimize the operation of sludge treatment processes and wastewater plants. This research aims to identify new tools and methods that can be used for in- line and real-time characterization and monitoring of sludge. Two methods that were examined in this thesis that have potential to be used as monitoring technologies were ultraviolet/visible spectrophotometry and torque rheology. Effluent and filtrate absorbance measurements in the ultraviolet/visible range were successful in monitoring the progress of aerobic digestion. Torque rheology was not found to be sensitive enough for monitoring aerobic digestion of sludge, however it was able to detect changes in the total solids content of anaerobically digested sludge. Torque rheology detected significant changes in anaerobically digested sludge when trivalent cations were added, but not when divalent cations were added. i Acknowledgements First off, I would like to thank my supervisor Dr. Banu Ormeci. Her guidance, knowledge and motivation throughout the entire process was so helpful. She has had such a positive influence on my life and I will forever be grateful. I would also like to thank Dr. Marie Tudoret Chow for continuous support and help in the lab and Rich Kibbie for taking the time in the lab to help me out. Additionally, I would like to thank my family and friends. They were so supportive throughout the thesis and were always there to give me words of encouragement and keep me on track. ii Table of Contents Abstract ............................................................................................................................................ i Acknowledgements ......................................................................................................................... ii List of Tables .................................................................................................................................. x List of Figures ................................................................................................................................ xi List of Appendices ....................................................................................................................... xvi List of Abbreviations .................................................................................................................. xvii Chapter 1 – Introduction ................................................................................................................. 1 Chapter 2 – Literature Review ........................................................................................................ 7 2.1 Types of sludge and sludge treatment .................................................................................. 7 2.1.1 Preliminary Sludge............................................................................................................. 7 2.1.2 Primary Sludge................................................................................................................... 8 2.1.3 Waste Activated Sludge (WAS) ........................................................................................ 8 2.1.4 Aerobic Digestion .............................................................................................................. 9 2.1.5 Anaerobic Digestion ........................................................................................................ 10 2.2 Regression Analysis Methods ............................................................................................ 11 2.2.1 Multivariate Regression (MLR) ....................................................................................... 11 2.2.2 Principle Components Regression (PCR) ........................................................................ 11 2.3 Lab-based tools and methods for sludge monitoring ......................................................... 11 2.3.1 Volatile Solids Reduction (VSR) ..................................................................................... 12 iii 2.3.2 Chemical Oxygen Demand (COD) .................................................................................. 14 2.3.3 Pathogen Reduction ......................................................................................................... 17 2.3.4 Odour ............................................................................................................................... 19 2.3.5 Specific Oxygen Uptake Rate (SOUR)............................................................................ 21 2.3.6 Gas Production ................................................................................................................. 23 2.4 Potential real-time tools and methods for sludge monitoring ............................................ 24 2.4.1 Ultraviolet/visible (UV-Vis) spectrophotometry ............................................................. 24 2.4.2 Rheology .......................................................................................................................... 26 2.4.3 Near-Infrared Spectroscopy (NIS) ................................................................................... 27 2.4.4 Electrical Impedance Spectroscopy (EIS) ....................................................................... 28 2.4.5 Image Based Analysis ...................................................................................................... 29 Chapter 3 – Materials and Methods .............................................................................................. 31 3.1 Aerobic Digestion Experiments ......................................................................................... 31 3.1.1 Batch aerobic reactor setup .............................................................................................. 32 3.1.2 Rheological measurements: TTQ method ....................................................................... 34 3.1.3 Absorbance ...................................................................................................................... 35 3.1.4 Regression Analysis ......................................................................................................... 36 3.1.5 Microscopy ...................................................................................................................... 39 3.1.6 Floc Area .......................................................................................................................... 40 3.1.7 Chemical Oxygen Demand (COD) .................................................................................. 40 iv 3.1.8 Total solids (TS) and total volatile solids (VS) ............................................................... 40 3.1.9 Protein .............................................................................................................................. 41 3.1.10 Carbohydrate .................................................................................................................. 43 3.1.11 Turbidity ........................................................................................................................ 44 3.1.12 Dissolved Oxygen (DO) ................................................................................................ 45 3.1.13 pH ................................................................................................................................... 45 3.1.14 Sludge Samples .............................................................................................................. 46 3.1.15 Centrifugation ................................................................................................................ 46 3.1.16 Filtration ......................................................................................................................... 46 3.2 Rheological Characterization ............................................................................................. 47 3.2.1 Rheological measurements: Totalized torque (TTQ) method ......................................... 49 3.2.2 Rheological measurements: Direct injection method ...................................................... 49 3.2.3 Sludge pretreatment with MgCl2 x 6H2O, CaCl2, FeCl3 x 6H2O, and alginate for TTQ method....................................................................................................................................... 50 3.2.4 Sludge pretreatment with CaCl2 and alginate for TTQ method ....................................... 50 3.2.5 Variation of total solids content for TTQ method ........................................................... 51 3.2.6 Microscopy ...................................................................................................................... 51 3.2.7 Floc area ........................................................................................................................... 51 3.2.8