LUẬN văn THẠC sĩ anaerobic co digestion of swine wastewater and kitchen refuse effect of pre treatment on substrate solubilization biodegrability

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 Prof 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 Prof Dr 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 VI INTRODUCTION VII Problem statement VII Scope of the study .VIII Objectives of the study .VIII Thesis structure VIII CHAPTER LITERATURE REVIEW 1.1 1.2 Anaerobic Digestion: a brief history Anaerobic digestion: a general overview 1.2.1 Hydrolysis stage 1.2.2 Acidogenesis stage 1.2.3 Acetogenesis stage 1.2.4 Methanogenesis stage 1.2.5 Rate-limiting step of anaerobic digestion 1.3 Operational parameters 1.3.1 Temperature 1.3.2 pH 1.3.3 Carbon/Nitrogen ratio 1.3.4 Inhibitory/Toxicity 1.4 Anaerobic co-digestion process 1.4.1 Terminology 1.4.2 Substrates for anaerobic co-digestion 10 1.4.3 AcoD of swine slurry and kitchen refuse 10 1.5 Pre-treatment process 13 1.5.1 Physical pre-treatment 13 1.5.2 Thermal pre-treatment 14 1.5.3 Chemical pre-treatment 14 1.5.4 Biological pre-treatment 15 1.6 Outputs from literature review 18 CHAPTER METHODOLOGY 19 2.1 Sampling protocol 19 2.1.1 Swine slurry 19 2.1.2 Kitchen refuse 19 2.1.3 Inoculum 19 2.2 Sample analysis 20 2.2.1 pH measurement 20 2.2.2 Chemical oxygen demand (COD) measurement 20 2.2.3 Nitrogen 21 2.2.4 Solids 21 2.2.5 Volatile Fatty Acids to Alkalinity Ratio 22 II LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com 2.3 Pre-treatment conditions 23 2.3.1 Thermal Pre-treatment 23 2.3.2 Pre-treatment using Peracetic acid (PAA) 23 2.4 Operation guideline for determination of biomethane potential (BMP) in batch reactor with respirometer equipment 24 2.4.1 Purpose and scope 24 2.4.2 General information 24 2.4.3 Preparation prior to BMP assays 25 2.4.4 Experimental set up 27 2.4.5 During the experiment 28 2.4.6 End of experiment 28 2.4.7 Data processing 28 CHAPTER EXPERIMENTAL RESULTS 33 3.1 Determination of BMP of swine slurry and kitchen refuse in mono-digestion and co-digestion mode 33 3.1.1 Objective 33 3.1.2 Sample characteristics 33 3.1.3 Summary of the method 34 3.1.4 Experimental results 34 3.2 Effect of thermal pre-treatment on co-substrate (KR1:SS1 = 1:3 on VS basis) solubilisation and biodegradability 36 3.2.1 Objective 36 3.2.2 Summary of the method 37 3.2.3 Experimental results 38 3.3 Effect of PAA pre-treatment on co-substrate C1 (KR1:SW1 = 1:3 on VS basis) solubilisation and biodegradability 47 3.3.1 Objective 47 3.3.2 Summary of the method 47 3.3.3 Experimental results 48 CONCLUSION 53 REFERENCE 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 Figure 1.2 Growth of methanogens in different temperature ranges Figure 3.1 Methane production profile of swine slurry and kitchen refuse in co-digestion and mono-digestion mode 35 Figure 3.2 pCOD solubilisation enhancement of co-substrate C1 (KR1:SS1 = 1:3) on VS basis) at various temperature and time 39 Figure 3.3 VSS solubilisation enhancement at various temperature and treatment time 42 Figure 3.4 Cumulative methane volume of inoculum, non-treated and thermal treated co-substrate C1 (KR1:SS1 = 1:3 on VS basis) 43 Figure 3.5 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 Table 1.2 Threshold level of light metallic and heavy metallic inhibitors [14] Table 1.3 Different substrates classified into higher and lower C/N ratio 10 Table 1.4 Co digestion practice of kitchen refuse, cattle slurry and related substrates 12 Table 1.5 Pre-treatment for anaerobic digestion of swine slurry, food waste in mono – digestion and mono – digestion mode 16 Table 2.1 Fitting experimental data with first – order model to define BMP and khyd 31 Table 3.1 Characteristic of swine slurry and kitchen refuse derived from different sources with standard deviation 33 Table 3.2 BMP of substrate and co–substrate with standard deviation 35 Table 3.3 sCOD and tCOD measurement before and after thermal pre-treatment 38 Table 3.4 COD solubilization enhancement at various temperature and time 39 Table 3.5 VSS before and after thermal pre-treatment of co-substrate (KR1:SS1 = 1:3) on VS basis) at various temperature and treatment time 40 Table 3.6 VSS solubilization enhancement of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) at various temperature and time with standard deviation 41 Table 3.7 BMP of non-treated and thermal-treated co-substrate C1 (KR1:SS1 = 1:3 on VS basis) with standard deviation 43 Table 3.8 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via theoretical approach 44 Table 3.9 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via experimental approach in comparison with theoretical approach 45 Table 3.10 Estimated hydrolysis rate constant (khyd), Ultimate methane production (B0), technical time T80 using first-order model compared with experimental data 46 Table 3.11 Solubilization enhancement in terms of pCOD in co-substrate C1 (KR1: SS1 = 1:3 on VS basis) 48 Table 3.12 Solubilization enhancement in terms of VSS destruction in co-substrate C1 (KR1: SS1 = 1:3 on VS basis) 49 Table 3.13 BMP of non-treated and PAA - treated co – substrates 50 Table 3.14 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via theoretical approach 51 Table 3.15 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via experimental approach in comparison with theoretical approach 51 Table 3.16 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.g 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.com one (Cost-Treatment-Recovery-No discharge) by changing from conventional energy- consuming into energy-producing anaerobic one, which is also integrated with resource recovery processes [4-6] 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 cosubstrate solubilization and biodegradability, associated with corresponding kinetic constants Thesis structure The thesis is structured into chapters Chapter 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 Chapter serves to present significant conclusion of this study and recommendation for future work VIII LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Table 3.9 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via experimental approach in comparison with theoretical approach Sample C1: Non–treated C1: 80 oC, 30’ C1 160 oC, 30’ Theoretical Biodegradability (%) 55.40% 61.55% 69.05% tCODinf (mg/l) 10,632 10,731 10,644 Experimental tCODeff Biodegradability (mg/l) (%) 4,524 57.45% 4,021 62.53% 3,024 71.59% There is a relatively good correlation between biodegradability obtained from two different methods, suggesting an acceptable variance of experimental results From this point, it could be concluded that biodegradability of co-substrate increase along the rise of applied pre-treatment temperature Compared with non–treated sample, 80 oC pre–treatment offer a surge of 8.84% (from 57.45% to 62.53%) where corresponding figure of 160 oC pre–treatment was nearly three times, at 24.61% (from 57.45% to 71.59%) A possible explanation is that thermal treatment prior to anaerobic digestion resulted in conversing un-biodegradable substrates into biodegradable substrates The higher temperature applied, the more significant improvement was observed 3.2.3.4 Model–based analysis of BMP assays Besides determining BMP values, cumulative methane profile can be further employed for determining hydrolysis rate constant (khyd) In reality, both of these kinetic value equally hold importance in designing anaerobic digestion system In order to compare methane production kinetics of the non – treated and thermal – treated co – substrates, hydrolysis rate constant was defined by fitting experimental data from BMP assays to first-order kinetic model: B  B0  1  exp(khyd  t)  Where B0 represent ultimate methane production from a given amount of substrate, whereas B indicates cumulative methane volume at a specific time (day) and k hyd is 45 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com hydrolysis rate constant (day-1) Simulated methane generation data employing first – order model are shown in Table 3- 10 Table 3.10 Estimated hydrolysis rate constant (khyd), Ultimate methane production (B0), technical time T80 using first-order model compared with experimental data Sample B0 (experimental) (Nml CH4 g-1 VS) B0 (simulated) (Nml CH4 g-1 VS) khyd (day-1) T80 day R2 C1 Non-treated C1: 80 oC, 30 minutes C 160 oC, 30 minutes 240.34 ± 11.73 269.71 ± 14.85 301.19 ± 16.98 246.83 ± 7.67 271.12 ± 10.95 303 ± 8.67 0.213 (day-1) 0.239 (day-1) 0.297 (day-1) 7.55 day 6.74 5.42 0.996 0.988 0.991 As can be seen from table 3.10, R2 value ranged from 0.988 to 0.996, indicating a good reflection of first-order model to experimental data Negligible difference was observed between experimental and simulated B0 As for the value of khyd, a significant increase was observed, from 0.213 day-1 (non – treated sample) to 0.239 day-1 (80 oC, 30 minutes sample) and 0.297 day-1 (160 oC, 30 minutes sample) sample Significant conclusion could be drawn based on determination of B0 and khyd Firstly, increase in simulated BMP could reconfirm the hypothesis that a part of unbiodegradable material in co-substrate was converted into biodegradable material under the effect of thermal – treatment, resulting in improvement of biomethanation in various degree Secondly, increase in hydrolysis rate constant khyd could be consider as a direct link between “solubilization” effect and increased rate of biodegradation From simulated data, another notable parameter is T80, i.e the time at which cumulative methane production reaches 80% maximum volume It is interesting to note that pre-treatment at 80 oC, 30 minutes lead to a decrease of T80 (from 7.55 day to 6.74 day), compared to 5.42 day obtained at 80 oC, 30 minutes 46 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Considering that anaerobic digestion is often carried out in long SRT, such changes could bring out positive effects, such as shortened SRT or decreased reactor size 3.3 Effect of PAA pre-treatment on co-substrate C1 (KR1:SW1 = 1:3 on VS basis) solubilisation and biodegradability 3.3.1 Objective Up to now, several of oxidants such as ozone, hydrogen peroxide, Fenton, etc have been combined with anaerobic digestion in order to break down complex-structured substances and thus enhance hydrolysis rate Among those oxidants, peracetic acid has emerged as a promising agent, with high oxidation potential of 1.8 eV The remarkable advantage of PAA is that the oxidation of organic materials by PAA occurs through formation of hydroxyl radicals These hydroxyl radical react with organic material following below equation RH + OH* → H2O + R (Eq 3.1) Afterwards, generated hydroxyl radical will continuously react with further component PAA finally degrades into acid acetic and water, contributing to biomethanation since the former product is of high biodegradability The main objective of the experiment is to evaluate the effect of PAA pre-treatment on solubilization and biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) Accordingly, tCOD, sCOD and VSS contents were investigated in a similar approach carried out in thermal pre – treatment experiment The difference is that co -substrate was subjected to various dose of PAA mixture rather than changes in temperature and treatment time 3.3.2 Summary of the method 3.3.2.1 PAA pre-treatment experiment The pre-treatment experiment was performed following procedure described as follows: 47 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com  Firstly, PAA is formulated by mixing M H2O2 and M CH3COOH at the ratio of 1:2 in dark condition (at room temperature) The mixture is left overnight for reaction completion  Secondly, PAA mixture is added to co-substrate at various dose (10, 20, 50 ml g-1 VS) Mixture of PAA and co-substrate is continuously mixed at room temperature for 12 hour for completion of all reactions  After the treatment time was finished, reactor flasks are ready for solubilization evaluation tests and BMP assays 3.3.2.2 Evaluation of solubilization After pre – treatment experiment, co – substrate is analyzed in terms of COD (sCOD, tCOD) and VSS destruction, following the same procedure described in section 3.2.2.2 3.3.2.3 BMP assays Upon the completion of pre – treatment experiment, pre – treated sample is further subjected to BMP assays to evaluate change in biomethanation and biodegradability, as previously discussed in section 2.4 3.3.3 Experimental results 3.3.3.1 COD solubilization enhancement COD measurement before and after PAA pre-treatment experiment were determined to evaluate the effect of thermal pretreatment on COD solubilization Table 3.10 illustrated the results of the TCOD and SCOD analysis for thermal treatment at the dose of 10, 20, and 50 ml, respectively As can be clearly seen, significant changes in terms of COD solubilization were recognized in term of COD solubilization enhancement, thus reflecting the impact of PAA on solubilizing materials Table 3.11 Solubilization enhancement in terms of pCOD in co-substrate C1 (KR1: SS1 = 1:3 on VS basis) Dose (ml g-1 VS) 10 (ml g-1 VS) 20 (ml g-1 VS) 50 (ml g-1 VS) 48 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com sCOD (mg/l) 4,514 ± 110 5,094 ± 150 5,423 ± 137 7,457 ± 82 tCOD (mg/l) 21,075 ± 193 20,186 ± 235 21,264 ± 390 21,122 ± 235 pCOD S.E (%) 0% 12.86 ± 1.93% 30.56 ± 2.56% 65.6 ± 2.23% Table 3.12 Solubilization enhancement in terms of VSS destruction in co-substrate C1 (KR1: SS1 = 1:3 on VS basis) Dose VSS (mg/l) VSS S.E (%) (ml g-1 VS) 10 (ml g-1 VS) 20 (ml g-1 VS) 50 (ml g-1 VS) 2,358 ± 79 2,119 ± 67 1,585 ± 36 976 ± 26 0% 10.12 ± 1.18% 32,78 ± 3,14% 58.6 ± 4.43% As can be seen from table 3-10, tCOD concentration fluctuated from 20,186 to 21,264 mg/L, with the variance of 0.4% between highest and lowest tCOD These results, however, are contradict with hypothesis stated section 3.3.1, which proposed that higher tCOD should be observed along with increasing dose of PAA mixture due to the reason that acid acetic is a highly biodegradable Further works are in requirement to confirm this findings On the other hand, interestingly, solubilization enhancement effects in terms of pCOD and VSS destruction are found in highly positive results, up to 65.6 ± 2.23% and 58.6 ± 4.43% respectively 3.3.3.2 Evaluation of BMP and biodegradability 1) BMP Cumulative methane volume of inoculum, non-treated and thermal treated cosubstrate is given in figure 3.5, followed by BMP calculation in table 3-13 49 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Figure 3.5 Cumulative methane volume of non-treated and PAA treated cosubstrate C1 (KR1:SS1 = 1:3 on VS basis) Table 3.13 BMP of non-treated and PAA - treated co – substrates 20 (ml g-1 VS) 599.28 ± 11.68 535.08 ± 10.43 31.49 ± 0.78 50 (ml g-1 VS) 600.54 ± 11.77 536.20 ± 10.51 31.49 ± 0.78 VS (g) 2.01 2.01 2.01 -1 BMP (Nml g CH4) 262.67 ± 8.81 252.13 ± 10.23 262.72 ± 11.02 VS: Methane volume generated from “sample” (inoculum + co – substrate) VI: Methane volume generated from “blank” (merely inoculum) 2.01 264.11 ± 9.46 Dose VS (ml CH4) VS (Nml CH4) VI (Nml CH4) (ml g-1 VS) 625.98 ± 19.67 558.92 ± 17.57 31.49 ± 0.78 10 (ml g-1 VS) 604.15 ± 20.69 539.42 ± 18.47 31.49 ± 0.78 In general, experimental results were produced in duplicate with an acceptable variance The amount of methane generated from “blank” (inoculum) merely account for less than 6% of “sample” (inoculum + co-substrate), which is within range recommended in Holiger’s work [46] Regarding BMP values, BMP of non– treated sample and sample subjected to different dose of PAA (10, 20, 50 ml g-1 VS) mixture were respectively at 262.67 ± 8.81, 252.13 ± 10.23, 262.72 ± 11.02 Nml CH4 g-1 VS The lowest BMP of 252.13 ± 10.23 might be resulted from errors 50 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com occurring in experimental procedure rather than a significant decrease in BMP trend From this standpoint, it seemed that the addition of PAA into co-substrate C1 (KR1:SW1 = 1:3 on VS basis) did not come along with improved BMP that previously observed in thermal pre-treatment experiment 2) Biodegradability Biodegradability of co-substrate can be evaluated via theoretical and/or experimental approach as respectively demonstrated in table 3-14 and 3-15 Table 3.14 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via theoretical approach VS (Nml CH4) CODCH4 (mg) tCODinf (mg/L) Vreactor (L) Biodegradability (%) C1: Non-treated 558.92 1594.28 21,075 0.125 62.12% C1, dose: 10 ml g-1 VS 539.42 1541.32 20.186 0.125 60.04% C1: dose: 20 ml g-1 VS 535.08 1528.85 21,264 0.125 63.05% C1: dose: 50 ml g-1 VS 536.20 1532.21 21,122 0.125 62.13% Sample Table 3.15 Biodegradability of co-substrate C1 (KR1:SS1 = 1:3 on VS basis) evaluated via experimental approach in comparison with theoretical approach Sample C1: Non-treated C1, dose: 10 ml g-1 VS C1: dose: 20 ml g-1 VS C1: dose: 50 ml g-1 VS Theoretical Biodegradabili ty (%) 60.51% 61.08% 59.05% 59.92% tCODinf (mg/l) 21,075 20.186 21,264 21,122 Experimental tCODeff Biodegradability (mg/l) (%) 7,457 64.62% 7.368 63.50% 7,545 64.51% 7,687 63.61% There is a relatively good correlation between biodegradability obtained from two different methods, suggesting a reliability of experimental results From this point, it could be concluded that biodegradability of co – substrate did not remarkably change along the increase of PAA dose 51 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com 3.3.3.3 Model – based analysis of BMP analysis The simulated methane generation curves employing first – order model are shown in Table 3- 16 Table 3.16 Estimated hydrolysis rate constant (khyd), Biomethane potential (B0), and technical time T80 employing first – order model B0 (exp) B0 (model) khyd T80 R2 C1, ml g-1 VS 262.67 264.18 0.206 (day-1) 7.81 day 0.996 C1, 10 ml g-1 VS 252.13 255.41 0.259 (day-1) 6.21 0.994 C1, 20 ml g-1 VS 262.72 266.78 0.297 (day-1) 5.41 0.993 C1, 50 ml g-1 VS 264.11 267.31 0.435 3.69 0.996 With R2 value ranging from 0.993 to 0.996, it can be assumed the model reasonably reflect experimental data As can be seen, negligible variation between simulated and experimental BMP was observed As for the value of khyd, a significant increase was observed, from 0.206 day-1 (non – treated sample) to 0.259 day-1 (dose: 10 ml g1 VS), 0.297 day-1 (dose 20 ml g-1 VS), and 0.435 day-1(dose 50 ml g-1 VS) In this case, the remarkable difference between thermal and PAA pre-treatment were clearly noticed While thermal pre-treatment resulted in improvement in both terms of BMP and khyd, PAA treatment can merely account for accelerating hydrolysis phase However, increased khyd was observed to be highly positive, which is reflected by a two-fold decrease in T80 value However, the reason why BMP could not be improved along increased dose of PAA needs further studied to be answered 52 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com CONCLUSION Operation guideline on BMP test was established at VJU-MEE Lab It made MEE Lab ready to be involved in on-going MONRE Project “No Waste-Recycle Cities” 2019-2021 BMP of swine slurry and three typical categories of KR were determined in monodigestion and co-digestion mode BMP of swine slurry was defined = 178 ± 6.14 and 189 ± 8.54 Nml CH4 g-1 VS at different period, while corresponding figure of household kitchen refuse (KR1), meat waste (KR2), and fruit waste (KR3) were 432 ± 8.76, 740 ± 35.89, and 541 ± 22.28, respectively In co-digestion mode, BMP of co-substrate C1 (KR1:SS1 = on 1:3 VS ratio) was at 256 ± 5.20 Nml CH4 g-1 VS, whereas number of co-substrate C2 (KR2:SS2 = on 1:3 VS ratio) was 337 ± 9.03 Nml CH4 g-1 VS Thermal pre-treatment at two different T (80 oC, 160 oC) showed its effects on solubilization and biodegradability of co-substrate C1 Higher temperature pretreatment (160 oC) showed larger solubilization enhancement; treatment time = 30minute Biodegradability was also improved, from 55.40% (non-treated sample) to 69.05% (160oC pre-treatment in 30 minutes) Peracetic acid, produced in VJU laboratory, showed an interestingly positive enhancement in terms of pCOD solubilization and VSS destruction, with the respective highest improvement of 65.6 ± 2.23% and 58.6 ± 4.43% recorded at the dose of 50 ml g-1 VS On the contrary, however, biodegradability of co-substrates did not change along increased dose, differing PAA treatment from thermal pretreatment Deeper research is needed 53 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com 54 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com REFERENCE [1]Cyberpac, D (2013) Towards the circular economy [online] www.ellenmacarthurfoundation.org [2]Alleman, J., & Prakasam, T (1983) Reflections on Seven Decades of Activated Sludge History Journal (Water Pollution Control Federation), 55(5), 436443 [3]A Buswell, "The Biology of Activated Sludge: An Historical Review", Sewage Works Journal, vol 3, no 3, pp 362 - 369, 1931 [4]Costa, A.; Ely, C.; Pennington, M.; Rock, S.; Staniec, C.; Turgeon, J Anaerobic Digestion and its Applications; US Environmental Protection Agency: Washington, DC, USA, 2015; p 24 [5]S Chiu and I Lo, "Reviewing the anaerobic digestion and co-digestion process of food waste from the perspectives on biogas production performance and environmental impacts", Environmental Science and Pollution Research, vol 23, no 24, pp 24435-24450, 2016 Available: 10.1007/s11356-016-7159-2 [6 ]K Hagos, J Zong, D Li, C Liu and X Lu, "Anaerobic co-digestion process for biogas production: Progress, challenges and perspectives", Renewable and Sustainable Energy Reviews, vol 76, pp 1485-1496, 2017 [7]G Lettinga, "Anaerobic digestion and slurry treatment 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Determination of BMP of swine slurry and kitchen refuse in monodigestion and co- digestion mode 3.1.1 Objective In this section, anaerobic digestion of swine slurry (SW) and Kitchen Refuse (KR)... LUONG download : add luanvanchat@agmail.com Figure 3.1 Methane production profile of swine slurry and kitchen refuse in co- digestion and mono -digestion mode Table 3.2 BMP of substrate and co? ? ?substrate. .. standard deviation Sample I MSS1 MSS2 MKR1 MKR2 MKR3 C1 C2 Description Inoculum Mono digestion of SS (SS1) Mono digestion of SS (SS2) Mono digestion of kitchen refuse (KR1) Mono digestion of