VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY DANG TRUNG HIEU ANAEROBIC CO-DIGESTION OF SWINE WASTEWATER AND KITCHEN REFUSE: EFFECT OF PRE-TREATMENT ON SUBSTRATE SOLUBILIZATION & BIODEGRADABILITY MASTER ‘S THESIS Hanoi, May 30, 2019 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY DANG TRUNG HIEU ANAEROBIC CO-DIGESTION OF SWINE WASTEWATER AND KITCHEN REFUSE: EFFECT OF PRE-TREATMENT ON SUBSTRATE SOLUBILIZATION & BIODEGRADABILITY MAJOR: ENVIRONMENTAL ENGINEERING CODE: PILOT SUPERVISORS Principal Supervisor: Assoc. Cao The Ha Co-Supervisor: Prof. Hidenari Yasui Hanoi, May 30, 2019 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com ACKNOWLEDGEMENT First of all, I would like to express my deepest appreciation to all those who provided me the possibility to complete this master thesis. A special gratitude is given to my supervisors, Assoc.
Cao The Ha and Prof. Hidenari Yasui, who provided me precious lessons and granted the permission to practice with all required laboratory equipment and necessary materials. I would further like to acknowledge with much appreciation the crucial role of lecturers whose contribution in stimulating suggestions and encouragement since the my very first days in Vietnam Japan University. I am also grateful to all of my classmate, those who always be by my side through work and play.
I am also in debt of my beloved colleagues in the University of Kitakyushu, those who generously offer a hand to help me quickly adapt with the internship course in a far-away country. Last but not least, many thanks go to the JICA whose financial support brings me such a great opportunity to broaden my horizon and sharpen my skills. These memorable days shall never be forgotten and be remarkable milestones in my career. I LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com TABLE OF CONTENTS ACKNOWLEDGEMENT.
I TABLE OF CONTENTS. II LIST OF FIGURES. IV LIST OF TABLES. V LIST OF ABBREVIATIONS.
VII Problem statement. VII Scope of the study .VIII Objectives of the study .VIII Thesis structure .1 Anaerobic Digestion: a brief history .2 Anaerobic digestion: a general overview .5 Rate-limiting step of anaerobic digestion .3 Carbon/Nitrogen ratio .4 Anaerobic co-digestion process .2 Substrates for anaerobic co-digestion.3 AcoD of swine slurry and kitchen refuse .5 Pre-treatment process .1 Physical pre-treatment .2 Thermal pre-treatment .3 Chemical pre-treatment .4 Biological pre-treatment .6 Outputs from literature review .2 Chemical oxygen demand (COD) measurement .5 Volatile Fatty Acids to Alkalinity Ratio. 22 II LUAN VAN CHAT LUONG download : add luanvanchat@agmail.3 Pre-treatment conditions .1 Thermal Pre-treatment .2 Pre-treatment using Peracetic acid (PAA) .4 Operation guideline for determination of biomethane potential (BMP) in batch reactor with respirometer equipment.1 Purpose and scope .3 Preparation prior to BMP assays .4 Experimental set up .5 During the experiment .6 End of experiment .1 Determination of BMP of swine slurry and kitchen refuse in mono-digestion and co-digestion mode 33 3.3 Summary of the method .2 Effect of thermal pre-treatment on co-substrate (KR1:SS1 = 1:3 on VS basis) solubilisation and biodegradability .2 Summary of the method .3 Effect of PAA pre-treatment on co-substrate C1 (KR1:SW1 = 1:3 on VS basis) solubilisation and biodegradability .2 Summary of the method. 55 III LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com LIST OF FIGURES Figure 1.1 Anaerobic digestion in different stages with generated products .2 Growth of methanogens in different temperature ranges .1 Methane production profile of swine slurry and kitchen refuse in co-digestion and mono-digestion mode .2 pCOD solubilisation enhancement of co-substrate C1 (KR1:SS1 = 1:3) on VS basis) at various temperature and time .3 VSS solubilisation enhancement at various temperature and treatment time .4 Cumulative methane volume of inoculum, non-treated and thermal treated co-substrate C1 (KR1:SS1 = 1:3 on VS basis) .5 Cumulative methane volume of non-treated and PAA treated co-substrate C1 (KR1:SS1 = 1:3 on VS basis).
50 IV LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com LIST OF TABLES Table 1.1 Free ammonia concentration and inhibitory effects on microbial activity .2 Threshold level of light metallic and heavy metallic inhibitors [14] .3 Different substrates classified into higher and lower C/N ratio .4 Co digestion practice of kitchen refuse, cattle slurry and related substrates .5 Pre-treatment for anaerobic digestion of swine slurry, food waste in mono – digestion and mono – digestion mode .1 Fitting experimental data with first – order model to define BMP and khyd .1 Characteristic of swine slurry and kitchen refuse derived from different sources with standard deviation .2 BMP of substrate and co–substrate with standard deviation .3 sCOD and tCOD measurement before and after thermal pre-treatment .4 COD solubilization enhancement at various temperature and time .5 VSS before and after thermal pre-treatment of co-substrate (KR1:SS1 = 1:3) on VS basis) at various temperature and treatment time .6 VSS solubilization enhancement of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) at various temperature and time with standard deviation .7 BMP of non-treated and thermal-treated co-substrate C1 (KR1:SS1 = 1:3 on VS basis) with standard deviation .8 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via theoretical approach.9 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via experimental approach in comparison with theoretical approach .10 Estimated hydrolysis rate constant (khyd), Ultimate methane production (B0), technical time T80 using first-order model compared with experimental data .11 Solubilization enhancement in terms of pCOD in co-substrate C1 (KR1: SS1 = 1:3 on VS basis) .12 Solubilization enhancement in terms of VSS destruction in co-substrate C1 (KR1: SS1 = 1:3 on VS basis) .13 BMP of non-treated and PAA - treated co – substrates .14 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via theoretical approach.15 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via experimental approach in comparison with theoretical approach .16 Estimated hydrolysis rate constant (khyd), Biomethane potential (B0), and technical time T80 employing first – order model. 52 V LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com LIST OF ABBREVIATIONS AD Anaerobic digestion AcoD Anaerobic co – digestion BMP Biomethane potential CETASD Center for Environmental Technology and Sustainable Development COD Chemical oxygen demand KR Kitchen refuse SS Swine slurry sCOD Soluble chemical oxygen demand pCOD Particulate chemical oxygen demand TCOD Total chemical oxygen demand TKN Total Kjehdahl Nitrogen TS Total solids TSS Total suspended solid VFAs Volatile fatty acids VS Volatile solids VSS Volatile suspended solids PAA Peracetic acid VI LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com INTRODUCTION Problem statement Towards a sustainable future, energy and nutrient security have undoubtedly been recognized as two of fundamental prerequisites. Centuries of predominant reliance on limited natural resources now bombard mankind with a burning questions on the future of next generations who would face with resource depletion in near future. In global scale, one of the red alerts has been sounded on a report titled “Towards a Circular Economy” from Ellen MacArthur Foundation.
“The world will be sitting on a time bomb by 2030, unless efforts to recovery materials are increased”, as noted on the report published in 2013 [1]. In attempts to utilize recoverable materials to their highest potential, much scientific attraction has been drawn on anaerobic digestion, which can be referred as to a fermentation process where organic matter is eventually converted into biogas and digestate. This technology has so far been considered as a viable solution to global energy and nutrient problems for several reasons. First, anaerobic digestion technology can provide cost-effective treatment to organic waste derived from numerous sources, e.
sewage sludge, concentrated black water, animal slurry, kitchen remains, food/beverage processing residues, energy crops, etc., compared to conventional anaerobic technology. Second, the incentive of utilizing biogas/methane as energy-carriers can turn out a typical waste treatment plants to be combined heat and electricity producing unit. Last but not least, anaerobic digestion industrial plant has so far been seen as energy – oriented, with less attention paid on nutrient recycling from digestate. This co – product mainly composed of partially converted organic fraction, biomass, and inorganic fraction (including nitrogen and phosphorus).
In further treatment, nitrogen and phosphorus is mobilized into liquid phase and consequently become supplied fertilizer. From a broader term, the application of anaerobic digestion could make a contribution to radical changes in history of waste treatment by changing the “conventional approach” (Cost-Treatment-Discharge) [2,3] to more “sustainable” VII LUAN VAN CHAT LUONG download : add luanvanchat@agmail. This master thesis, merely focuses on energy recovery in terms of energy recovery in terms of methane production. Scope of the study The genesis of this master thesis is prompted by author’s interest on application of anaerobic digestion technology, with a specific aim at energy recovery.
Batch anaerobic tests would be conducted on several types of waste, including kitchen refuse (household, meat groceries, and fruit groceries) and swine slurry, for the determination of Biomethane Potential. Furthermore, investigation would be carried out on the role of pre – treatment processes on substrate characteristics. Objectives of the study Establish operation guideline to define Biomethane Potential (BMP) of substrates using respirometer equipment. Determine Biological Methane Potential (BMP) of swine slurry and three kinds of kitchen refuse in separate and co-digestion mode.
Evaluate the effect of Thermal and Peracetic acid pre-treatment on co- substrate solubilization and biodegradability, associated with corresponding kinetic constants. Thesis structure The thesis is structured into 4 chapters. Chapter 1 outlines the reviewed literature regarding AD process, co-digestion practice, and pre – treatment processes. Sampling task, methodology employed in sample analysis, pre-treatment procedure, and operation guideline for determining BMP value will be presented in chapter 2, followed by results and discussion provided in chapter 3.
Chapter 4 serves to present significant conclusion of this study and recommendation for future work. VIII LUAN VAN CHAT LUONG download : add luanvanchat@agmail.1 Anaerobic Digestion: a brief history Historical evidences led us to believe that anaerobic digestion was among the oldest technologies ever employed. Babylonians and Egyptians, might be by accident, discovered the formation of vinegar and called it “home fermentation” as early as 5,000 years ago. More interestingly, biogas-heated bathing rooms found in ancient Assyria were traced back to even 10th century B.
Mankind seemed to apply anaerobic technique without understanding it until the 17th century, when Jan Baptita Van Helmont discovered the evolvement of flammable gases from decayed organic matter in lake sediment [9]. From this significant milestone, the proportion between the amount of degraded organic matter and generated flammable gas, and the presence of methane gas were later concluded by Alessandro Volta in 1776 and Sir Humphry Davy in 1808 in their respective works [8,9]. In the branch of slurry treatment, this technique might be first applied in airtight chamber designed by M. Louis Mouras in the late 1890s [8].
In spite of continuous development witnessed in the following decades, anaerobic digestion remained far from adequate public attention, with one of the reasons being unpleasant putrid associated [10]. On the other side, practitioners often faced with system failures owing to lack of comprehensive know-how on mechanism of reaction inside. During 1960s, the entire AD metabolic pathways associated with its optimizing condition and inhibitory effects were clearly illustrated in study works conducted by McCarty [10]. From this point onwards, anaerobic digestion process has gradually shifted to general acceptance and exhibited a promising capacity in dealing with high-strength slurry, along with huge potential on energy and nutrient recovery at community level.
1 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.2 Anaerobic digestion: a general overview Anaerobic digestion process can be define as to a series of biochemical conversion whereby organic matter was transformed in the absence of oxygen [11]. Upon the process completion, two main end-products are formed, namely biogas (gas mixture composed of CH4, CO2, H2S, H2O, etc.1 summarizes four consecutive stages occurring within the anaerobic digestion, each associated with generated products, adapted from Christiansen [11].1 Anaerobic digestion in different stages with generated products 2 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.