ANAEROBIC SEQUENCING BATCH REACTOR TREATMENT OF LOW STRENGTH SWINE MANURE AND CO-DIGESTION OF ENERGY DENSE BY-PRODUCTS By MATTHEW TODD STEELE Bachelor of Science in Biological and Agricultural Engineering Kansas State University Manhattan, Kansas 2003 Master of Science in Biological and Agricultural Engineering Kansas State University Manhattan, Kansas 2005 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY May, 2013 ANAEROBIC SEQUENCING BATCH REACTOR TREATMENT OF LOW STRENGTH SWINE MANURE AND CO-DIGESTION OF ENERGY DENSE BY-PRODUCTS Dissertation Approved: Dr. Douglas W. Hamilton Dissertation Adviser Dr. Hasan Atiyeh Dr. Gregory Wilber Dr. Scott Carter . ii ACKNOWLEDGEMENTS I would like to sincerely thank Dr. Douglas Hamilton for the opportunity to pursue a Ph.D. at Oklahoma State University. I would like to thank him for the all the support and advice he provided throughout the course of my research. I would also like to thank my wife Megan and children Jaelynn and Cooper for their love and support. iii Acknowledgements reflect the views of the author and are not endorsed by committee members or Oklahoma State University. Name: MATTHEW TODD STEELE Date of Degree: MAY, 2013 Title of Study: ANAEROBIC SEQUENCING BATCH REACTOR TREATMENT OF LOW STRENGTH SWINE MANURE AND CO-DIGESTION OF ENERGY DENSE BY-PRODUCTS Major Field: BIOSYSTEMS AND AGRICULTURAL ENGINEERING Abstract: The Anaerobic Sequencing Batch Reactor (ASBR) is a batch digester utilizing a single vessel for digestion and solids separation. Internal solids retention provides the ASBR with the ability to treat dilute solids wastewaters such as swine manure. A 430 m3 full scale ASBR at the Oklahoma State University Swine Research and Education Center was started in August of 2008 using a “cold start” technique and continuously operated for two years. After one year of operation, the HRT was incrementally reduced from 20 to 5 days, and the cycles per day was increased from one to two at a temperature of 20°C. Operation at the final parameters provided organic removals of 64% and a specific 3 -1 methane yield of 0.33 m CH4 kg VS . The dilute natural of swine manure provides the opportunity for co-digestion utilizing the ASBR. Co-digestion of crude glycerol from biodiesel production and swine manure in lab-scale ASBR systems was examined to determine the maximum stable crude glycerol inclusion rate for operation at a 5 day HRT and temperature of 20°C. The maximum inclusion rate for these parameters was found to be 1% (v/v) of the daily influent volume. The 1% inclusion resulted in a 7.3 fold increase -1 -1 in methane production, 21.2 l CH4 day compared 2.9 l CH4 day for swine manure only. A 92.5% conversion of crude glycerol COD to methane was observed at the 1% inclusion rate indicating the near complete utilization of co-digestion feedstock. The ASBR has been reviewed in detail lab-scale experiments with limited experience in full scale design and operation. Considerations for the design of a full scale ASBR for treatment of low strength swine manure should be based upon reactor energy balance and solids retention. The low organic loading of low strength swine manure results in low volumetric energy production necessitating the design process to include the reactor’s operational input energy requirements with respect to available energy production. The inclusion of the solids separation process within the reactor requires that the physical reactor design be based upon solids settling rates and solids retention capacity of the reactor vessel. iv TABLE OF CONTENTS Chapter Page I. INTRODUCTION ......................................................................................................1 II. REVIEW OF LITERATURE....................................................................................4 Introduction ..............................................................................................................4 ASBR Operational Parameters ................................................................................8 Anaerobic Digestion Process ...................................................................................9 Hydrolysis of Organic Solids ...........................................................................10 Hydraulic Retention Time ......................................................................................12 Solids Retention Time............................................................................................15 Settling ...................................................................................................................18 Sludge Wasting ......................................................................................................20 Mixing ....................................................................................................................20 Temperature ...........................................................................................................24 Digestion Substrates...............................................................................................26 Kinetics ..................................................................................................................29 Organic Loading Rate ............................................................................................36 ASBR Optimization for Treatment of Low Strength Swine Manure ....................38 Conclusions ............................................................................................................40 III. START-UP AND CONTINUOUS OPERATION OF AN ANAEROBIC SEQUENCING BATCH REACTOR (ASBR) TREATING LOW STRENGTH SWINE MANURE.................................................................................................41 Introduction ............................................................................................................41 Objectives ..............................................................................................................42 Materials and Methods ...........................................................................................43 Systems Monitored ..........................................................................................43 Digester Operation .................................................................................................48 Start-up Using “Cold Start” Technique ...........................................................50 Restart and Settling Depth Adjustment............................................................50 Mixing Intensity Adjustment ...........................................................................51 HRT Reduction ................................................................................................52 Steady 5 day HRT ............................................................................................53 Sampling and Analysis ..........................................................................................54 v Chapter Page Measurement of Digester Performance .................................................................54 Results and Discussion ..........................................................................................57 Organic Matter Mass Balance ..........................................................................61 Conclusions ............................................................................................................70 IV. CO-DIGESTION OF CRUDE GLYCEROL IN AN ANAEROBIC SEQUENCING BATCH REACTOR (ASBR) FED LOW STRENGTH SWINE MANURE ..............................................................................................................72 Introduction ............................................................................................................72 Objectives ..............................................................................................................74 Materials and Methods ...........................................................................................74 Materials Used .................................................................................................74 Model Reactors ................................................................................................76 Test Procedures ................................................................................................76 Analytical Methods ..........................................................................................77 Results and Discussion ..........................................................................................78 Mass Balance ...................................................................................................87 Conclusions ............................................................................................................93 V. CONSIDERATIONS FOR DESIGN OF ANAEROBIC SEQUENCING BATCH REACTORS TREATING SWINE EFFLUENT ....................................95 Introduction ............................................................................................................95 Objectives ..............................................................................................................98 Design Steps...........................................................................................................99 Influent Analysis ............................................................................................100