DOCTORADO EN INGENIERÍA - ÉNFASIS INGENIERÍA SANITARIA Y AMBIENTAL · 2025
Acidogenic fermentation for the production of volatile fatty acids from cassava sour starch extraction process wastewater
Cassava and its processed products, such as sour starch, form the economic backbone of various communities in Colombia. However, their production generates effluents with high organic loads, cyanide concentrations, and acidic pH levels, leading to significant deterioration of receiving wáter sources. If these discharges are not properly treated beforehand, bodies of water may become unsuitable for human consumption, fishing, or recreation. Previous research indicates that this type of wastewater can be treated through anaerobic digestion, yielding methane as the primary product. However, studies also suggest that the volatile fatty acids produced during the acidogenic phase of anaerobic digestion, known as acidogenic fermentation, have valuable applications in various chemical and biological processes. This doctoral thesis begins with an introduction to the environmental issues caused by effluents from sour starch extraction from cassava, along with an analysis of previous research and emerging trends in its treatment. It also outlines the challenges that motivated this study and led to the establishment of three specific objectives (Chapter 1). Next, acidogenic fermentation and volatile fatty acid production are examined as alternatives for wastewater treatment through a bibliometric análisis of existing scientific literature (Chapter 2). This analysis identified key operational variables, which were evaluated at the laboratory scale for the substrate of interest. The individual and interactive effects of fermentation time and pH (Chapter 3), as well as the substrate-microorganism relationship and temperature (Chapter 4), were examined. Additionally, recognizing the importance of modeling in complementing experimental trials and enhancing the understanding of biological processes, a kinetic study was conducted on the acidogenic fermentation of wastewater from cassava processing. This study identified the models that best fit soluble organic matter consumption and volatile fatty acid production (Chapter 5). Finally, this thesis synthesizes the results and outlines perspectives for future research in the field (Chapter 6).
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Contenido
- List of Tablesp. 8
- List of Figuresp. 9
- List of Abbreviationsp. 11
- Abstractp. 12
- Resumenp. 13
- Introductionp. 14
- Background and justificationp. 14
- Objectivesp. 16
- General Objectivep. 16
- Specific Objectivesp. 16
- Organization of the Thesisp. 17
- Analysisp. 119
- Introductionp. 14
- Materials and Methodsp. 20
- Results and Discussionp. 21
- Worldwide Scientific Production Related to VFA and Wastewater Fermentationp. 21
- Literature on VFA and Wastewater Fermentationp. 22
- Main Journals Publishing on VFA and Wastewater Fermentationp. 24
- Main Research Approaches on VFA Productionp. 26
- Future Perspectives and Challengesp. 41
- Conclusionsp. 42
- Acids from Cassava Wastewaterp. 43
- Introductionp. 14
- Materials and Methodsp. 20
- Substratep. 32
- Inoculump. 45
- Acidogenic Fermentation Experimentsp. 45
- Experimental Design and Statistical Analysesp. 46
- Analytical Methodsp. 47
- Results and Discussionp. 21
- Physicochemical Characterization of CWW and Inoculum Solids Concentrationp. 47
- Effect of Fermentation Time on VFA Productionp. 48
- Effect of Initial pH on VFA Productionp. 53
- Productionp. 32
- Future Perspectivesp. 61
- Conclusionsp. 42
- Ratio and Temperature on Volatile Fatty Acids Productionp. 63
- Introductionp. 14
- Materials and Methodsp. 20
- Substrate and Inoculump. 66
- Acidogenic Fermentation Assaysp. 66
- Experimental Design and Statistical Analysesp. 46
- Analytical Methodsp. 47
- Results and Discussionp. 21
- Physicochemical Characterization of CWW and Inoculum Solids Concentrationp. 47
- VFA Production, Yields, and Substrate Uptake from CWWp. 68
- Distribution of VFAs Produced from CWWp. 73
- Conclusionsp. 42
- Substratep. 32
- Introductionp. 14
- Materials and Methodsp. 20
- Substrate and Inoculump. 66
- Experimental Setupp. 80
- Analytical Methodsp. 47
- Kinetic Model Fittingp. 81
- Results and Discussionp. 21
- Physicochemical Characterization of Substrate and Inoculump. 84
- Yield, Productivity and VFA Distributionp. 84
- Kinetic Model Fitting of AFp. 88
- Conclusionsp. 42
- Conclusions and Future Perspectivesp. 97
- List of Productsp. 100
- Supplementary Materialp. 101
- Referencesp. 105
- from wastewater fermentationp. 24
- Table 2.2 Optimal pH for obtaining carboxylic acids from different types of wastewaterp. 32
- production of VFAs by AF of CWWp. 46
- Table 3.2 Coding of the factors used in the RCCDp. 47
- in the set of experimentsp. 48
- Table 3.5 Summary of one-way ANOVA for the FT variablep. 49
- Table 3.6 Summary of one-way ANOVA for the pH variablep. 54
- Table 3.7 Experimental results of the RCCD for the production of VFAs by AF of CWWp. 59
- independent variables and interactions at a 95% confidence level for the RCCDp. 60
- VFA production through the AF of CWWp. 67
- Table 4.2 Physicochemical characterization of CWW in the set of experimentsp. 68
- Table 4.4 Summary of one-way ANOVA results for the S/M ratio variablep. 69
- Table 4.5 Summary of one-way ANOVA results for the temperature variablep. 71
- the AF of CWWp. 82
- Table 5.2 The kinetic models selected for describing VFA production during the AF of CWWp. 82
- Table 5.3 Physicochemical characterization of CWW used as substrate in experimental setupp. 84
- Table 5.4 Concentration of total and volatile solids in inoculum utilized in experimental setupp. 84
- CWWp. 11
- Table 5.6 Kinetic parameters estimated by modeling of VFA production in AF of CWWp. 91
- Figure 2.1 Methodological scheme for bibliometric analysisp. 20
- Scopus databasep. 22
- Source: Scopus databasep. 22
- publication of 1 document. Source: Scopus databasep. 24
- Other areas contributed 6.3%. Source: Scopus databasep. 26
- Figure 2.7 Bibliometric network for studies on VFA and wastewater fermentationp. 27
- Figure 2.8 Word cloud of the abstracts. Words repeated more than 100 timesp. 27
- indicate the year in which the topic was most researchedp. 31
- Figure 3.1 Experimental unit used in the AF of CWWp. 45
- concentrations and uptakep. 48
- Figure 3.3 VFA distribution for the FTs evaluated in AF of CWWp. 50
- Figure 3.4 Pressure differentials measured in the acidogenic reactors for each FT evaluatedp. 52
- concentrations and uptakep. 48
- Figure 3.6 VFA distribution for different pH values evaluated in AF of CWWp. 56
- Figure 3.7 Pressure differentials measured in the acidogenic reactors for each pH evaluatedp. 58
- CWW. (a) Response surface and (b) contour plotp. 59
- Figure 4.1 Scheme of the unit and experimental procedure adopted in the AF of CWWp. 66
- of the temperaturep. 69
- and (b) effect of the temperaturep. 72
- of the temperaturep. 73
- (b) effect of the temperaturep. 76
- Figure 5.1 Final VFA concentration and yield by AF of CWWp. 84
- Figure 5.2 Productivity of VFAs from CWWp. 86
- Figure 5.3 Distribution of VFA produced in AF of CWWp. 87
- kinetic modelsp. 90
- predicted by best-fit modelsp. 93