scholarly journals Effect of the solid retention time in the obtention of polyhydroxyalkanoates

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 864
Author(s):  
Rolando Calero ◽  
Manuel Martínez
Keyword(s):  
Fatty Acids ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Solid Retention Time ◽  
Dry Cell Weight ◽  
Acidogenic Reactor ◽  
Mixed Microbial Cultures ◽  
Dry Cell

Background: The effect of solid retention time (SRT) over cheese whey substrates in a fermentation process drives changes in the composition of polyhydroxyalkanoates (PHAs) obtained. Volatile fatty acids produced in the first step of an anaerobic sequencing batch reactor were used as substrates to produce PHA using mixed microbial cultures under aerobic dynamic feeding conditions. Methods: Analytical methods were used for the standard analysis of parameters of interest including measuring the amount of ammonium and phosphate, chemical oxygen demand, among others. Results: The SRT increasing from 4 to 6 and 10 days produced changes in the distribution of volatile fatty acids produced. The polyhydroxybutyrate-hydroxyvalerate copolymers formed in the accumulation stage gave the following results: 58:42, 68:32 and 81:19 (%), referred to SRTs of 10, 6 and 4 days, respectively. The maximum PHA accumulation obtained at 10 days of SRT was 52% of the dry cell weight within 7 h, reaching a PHA productivity of 0.62 g L−1 h−1 and a storage yield of 0.37. Conclusion: The SRT variation impact on the distribution of volatile fatty acids in the acidogenic reactor and consequently on the PHA production and composition formed in the accumulation stage.

scholarly journals Influence of the total concentration and the profile of volatile fatty acids on polyhydroxyalkanoates (PHA) production by mixed microbial cultures

2021 ◽  
Author(s):  
Gloria Bravo-Porras ◽  
Luis A. Fernández-Güelfo ◽  
Carlos J. Álvarez-Gallego ◽  
María Carbú ◽  
Diego Sales ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Total Concentration ◽  
Degradation Process ◽  
Microbial Cultures ◽  
Dry Cell Weight ◽  
Cheap Alternative ◽  
Mixed Microbial Cultures ◽  
Pha Production ◽  
Dry Cell

AbstractPolyhydroxyalkanoates (PHAs) production from lignocellulosic biomass using mixed microbial cultures (MMC) is a potential cheap alternative for reducing the use of petroleum-based plastics. In this study, an MMC adapted to acidogenic effluent from dark fermentation (DF) of exhausted sugar beet cossettes (ESBC) has been tested in order to determine its capability to produce PHAs from nine different synthetic mixtures of volatile fatty acids (VFAs). The tests consisted of mixtures of acetic, propionic, butyric, and valeric acids in the range of 1.5–9.0 g/L of total acidity and with three different valeric:butyric ratios (10:1, 1:1, and 1:10). Experimental results have shown a consistent preference of the MMC for the butyric and valeric acids as carbon source instead other shorter acids (propionic or acetic) in terms of PHA production yield (estimated in dry cell weight basis), with a maximum value of 23% w/w. Additionally, valeric-rich mixtures have demonstrated to carry out a fast degradation process but with poor final PHA production compared with high butyric mixtures. Finally, high initial butyric and valeric concentrations (1.1 g/L and 4.1 g/L) have demonstrated to be counterproductive to PHA production.

scholarly journals Volatile Fatty Acids and Biomethane Recovery from Thickened Waste Activated Sludge: Hydrothermal Pretreatment’s Retention Time Impact

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1580
Author(s):  
Farokh laqa Kakar ◽  
Ahmed El Sayed ◽  
Neha Purohit ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Optimum Conditions ◽  
Pretreatment Temperature ◽  
Biomethane Production

The main objective of this study was to evaluate the hydrothermal pretreatment’s retention time influence on the volatile fatty acids and biomethane production from thickened waste activated sludge under mesophilic conditions. Six different retention times of 10, 20, 30, 40, 50, and 60 min were investigated while the hydrothermal pretreatment temperature was kept at 170 °C. The results showed that the chemical oxygen demand (COD) solubilization increased by increasing the hydrothermal pretreatment retention time up to 30 min and stabilized afterwards. The highest COD solubilization of 48% was observed for the sample pretreated at 170 °C for 30 min. Similarly, the sample pretreated at 170 °C for 30 min demonstrated the highest volatile fatty acids yield of 14.5 g COD/Lsubstrate added and a methane yield of 225 mL CH4/g TCODadded compared to 4.3 g COD/Lsubstrate added and 163 mL CH4/g TCODadded for the raw sample, respectively. The outcome of this study revealed that the optimum conditions for solubilization are not necessarily associated with the best fermentation and/or digestion performance.

scholarly journals Effect of Hydrothermal Pretreatment on Volatile Fatty Acids Production from Source-Separated Organics

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 576 ◽  
Author(s):  
Farokh laqa Kakar ◽  
Ehssan Hosseini Koupaie ◽  
Hisham Hafez ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Chemical Oxygen Demand ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Soluble Substance ◽  
Pretreatment Temperature

The current study investigates the effect of hydrothermal pretreatment (HTP) on acidification of source-separated organics (SSO) in terms of volatile fatty acids (VFAs) production and solubilization. Temperature and retention time for HTP of SSO ranged from 150 to 240 °C and 5 to 30 min, respectively. The soluble substance after hydrothermal pretreatment initially increased, reaching its peak at 210 °C and then declined gradually. The highest overall chemical oxygen demand (COD) solubilization of 63% was observed at “210 °C-20 min” compared to 17% for raw SSO. The highest VFAs yield of 1536 mg VFAs/g VSS added was observed at “210 °C-20 min” compared to 768 mg VFAs/g VSS for raw SSO. Intensification of hydrothermal pretreatment temperature beyond 210 °C resulted in the mineralization of the organics and adversely affected the process.

Influence of HRT (hydraulic retention time) and SRT (solid retention time) on the hydrolytic pre-treatment of urban wastewater

2001 ◽  
Vol 44 (4) ◽  
pp. 7-14 ◽  
Author(s):  
P. Ligero ◽  
A. De Vega ◽  
M. Soto
Keyword(s):  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Phase Iii ◽  
Urban Wastewater ◽  
Solid Retention Time ◽  
Start Up ◽  
Pre Treatment ◽  
Two Parameters ◽  
Hydrolysis Of

This work presents the results obtained from a study on the pretreatment of urban wastewater using a digester that acted as a system for the retention of solids (sedimentation-filtration), hydrolysis of the retained solids and acidification of the dissolved substances. After start-up (Phase I), the digester was operated at hydraulic retention times (HRT) of 4.4, 3.4 and 2.2 h and at solid retention times (SRT) of 24, 16 and 14 d, during Phases II, III and IV, respectively. The retention and removal of suspended solids (SS) was maintained slightly above 60%, independently of HRT and SRT. Conversely, eliminated chemical oxygen demand (COD) decreased slightly upon reducing HRT and SRT. The influence of these two parameters on the generation of volatile fatty acids (VFA) is more notable, reaching effluent VFA concentration of 29 (Phase II), 96 (Phase III), and 107 (Phase IV) mg COD/l. VFA to SS generation ratios were 0.13 (II), 0.35 (III), and 0.48 (IV) g VFACOD/g SS added. Optimum values were reached at an HRT of 2.2 h. Taking 100 kg influent COD as a base, the conversion of different kinds of COD was as follows (in kg influent:kg effluent): VFACOD (4:17), non-VFA soluble COD (45:23), VSSCOD (51:23). Simultaneously to these conversions, 2 kg VSSCOD are generated as purge stream and 35 kg COD are eliminated during the process.

scholarly journals Effect of pH and hydraulic retention time on volatile fatty acids production from real waste in dark fermentation process

2021 ◽  
Author(s):  
Muhammed Ali Abdullah Khan
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Biological Nutrient Removal ◽  
Waste Activated Sludge ◽  
Carbon Substrate ◽  
Primary Sludge

Waste-derived volatile fatty acids (VFAs) is an important carbon substrate for microorganisms engaged in the production of bioenergy, biodegradable plastics, and biological nutrient removal process. In this project, the generation and applications of waste-derived VFA were examined. Three solid wastes were used Primary sludge (PS), thickened waste activated sludge (TWAS) which were collected from Ashbridges Bay and source separated organics (SSO) that was collected from Disco Road facility. All the water quality analyses such as pH, TCOD, SCOD, TVFA, TSS, VSS, NH3 and, alkalinity were monitored. The results of this study showed that with increasing the Hydraulic retention time (HRT), the percentage of acidification increased. Furthermore, the results showed that alkaline pH was better than the acid pHs. Keywords: Total Volatile Fatty Acids, Soluble Chemical Oxygen Demand, Primary Sludge, Thickened Waste Activated Sludge, Source Separated Organics.

scholarly journals Modeling Of Dark Fermentation Process For Volatile Fatty Acids Production

2021 ◽  
Author(s):  
Raman Sharma
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Retention Time ◽  
Alternative Energy ◽  
Fossil Fuels ◽  
Fermentation Process ◽  
Volatile Fatty Acids ◽  
Solid Retention Time ◽  
Steady State Model ◽  
Complex Organic

This study examined the fermentation process for the production of volatile fatty acids from the organic waste. The depletion of fossil fuels motivated researchers to search for alternative energy and fuels instead of relying on the non-renewable way of energy and fuel production. Anaerobic digestion is a biochemical process in the absence of oxygen, where complex organic matter are degraded. The different stages of anaerobic digestion and important operating parameters such as pH, temperature and retention time. The most suitable feedstock and its effects on the treatment process are discussed. This study evaluates the modelling of VFAs production. The paper also demonstrates various model like ADM1, surface limiting model, and steady-state model. Furthermore, an experimental setup consisting of two semi-continuous reactors was employed for the sample analysis. The reactors were fed with raw and pre-treated source separated organics with solid retention time of 3 days. Keywords: Anaerobic digestion, Feedstocks, SSO, VFAs, ADM1

scholarly journals Modeling Of Dark Fermentation Process For Volatile Fatty Acids Production

2021 ◽  
Author(s):  
Raman Sharma
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Retention Time ◽  
Alternative Energy ◽  
Fossil Fuels ◽  
Fermentation Process ◽  
Volatile Fatty Acids ◽  
Solid Retention Time ◽  
Steady State Model ◽  
Complex Organic

This study examined the fermentation process for the production of volatile fatty acids from the organic waste. The depletion of fossil fuels motivated researchers to search for alternative energy and fuels instead of relying on the non-renewable way of energy and fuel production. Anaerobic digestion is a biochemical process in the absence of oxygen, where complex organic matter are degraded. The different stages of anaerobic digestion and important operating parameters such as pH, temperature and retention time. The most suitable feedstock and its effects on the treatment process are discussed. This study evaluates the modelling of VFAs production. The paper also demonstrates various model like ADM1, surface limiting model, and steady-state model. Furthermore, an experimental setup consisting of two semi-continuous reactors was employed for the sample analysis. The reactors were fed with raw and pre-treated source separated organics with solid retention time of 3 days. Keywords: Anaerobic digestion, Feedstocks, SSO, VFAs, ADM1

scholarly journals Effect of pH and hydraulic retention time on volatile fatty acids production from real waste in dark fermentation process

2021 ◽  
Author(s):  
Muhammed Ali Abdullah Khan
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Biological Nutrient Removal ◽  
Waste Activated Sludge ◽  
Carbon Substrate ◽  
Primary Sludge

Waste-derived volatile fatty acids (VFAs) is an important carbon substrate for microorganisms engaged in the production of bioenergy, biodegradable plastics, and biological nutrient removal process. In this project, the generation and applications of waste-derived VFA were examined. Three solid wastes were used Primary sludge (PS), thickened waste activated sludge (TWAS) which were collected from Ashbridges Bay and source separated organics (SSO) that was collected from Disco Road facility. All the water quality analyses such as pH, TCOD, SCOD, TVFA, TSS, VSS, NH3 and, alkalinity were monitored. The results of this study showed that with increasing the Hydraulic retention time (HRT), the percentage of acidification increased. Furthermore, the results showed that alkaline pH was better than the acid pHs. Keywords: Total Volatile Fatty Acids, Soluble Chemical Oxygen Demand, Primary Sludge, Thickened Waste Activated Sludge, Source Separated Organics.

scholarly journals Identifikasi Senyawa Asam Lemak Volatil dari Air Limbah Industri Minyak Kelapa Sawit untuk Produksi Polihidroksialkanoat oleh Ralstonia eutropha JMP 134

2021 ◽  
Vol 11 (01) ◽  
pp. 49
Author(s):  
Martha Aznury ◽  
Tjandra Setiadi
Keyword(s):  
Fatty Acids ◽  
Palm Oil ◽  
Industrial Wastewater ◽  
Volatile Fatty Acids ◽  
Ralstonia Eutropha ◽  
Bacterial Fermentation ◽  
Dry Cell Weight ◽  
Pha Production ◽  
Palm Oil Mill ◽  
Dry Cell

Identification of Volatile Fatty Acids from Palm Oil Mill Effluent for Polyhydroxyalkanoate Production by Ralstonia eutropha JMP 134 Abstract Polyhydroxyalkanoate (PHA) is a bioplastic which is derived from bacterial fermentation. In this study, PHA is produced by utilizing Ralstonia eutropha JMP 134 and volatile fatty acids (VFA) from palm oil industrial wastewater as a precursor. The aim of this research is to study the effect of carbon source, addition time, and VFA concentration on PHA production by fermentation using Ralstonia eutropha JMP 134 in batch. PHA and dry cell weight (DCW) concentrations obtained by adding VFA from palm oil industrial wastewater in batches at 20 and 40 hours were 0.014 g/L.hour, 2.76 g/L and 3.66 g/L, respectively. The results also showed that the time of adding VFA greatly affected cell growth, with the best addition time being after the 20th hour. Keywords: palm oil industrial wastewater, polyhydroxyalkanoate (PHA), batch, Ralstonia eutropha JMP 134, volatile fatty acids (VFA) Abstrak Polihidroksialkanoat (PHA) adalah bioplastik yang diproses melalui proses fermentasi dengan mikroba. Pada penelitian ini, PHA diproduksi dengan menggunakan Ralstonia eutropha JMP 134 dan memanfaatkan asam lemak volatil (ALV) dari air limbah industri minyak kelapa sawit sebagai prekursor. Penelitian ditujukan mempelajari pengaruh sumber karbon, waktu penambahan, dan konsentrasi ALV terhadap  poduksi PHA yang difermentasi menggunakan Ralstonia eutropha JMP 134 secara batch. Konsentrasi PHA dan berat kering sel (BKS) yang diperoleh pada penambahan ALV dari air limbah industri kelapa sawit secara batch pada jam ke-20 dan 40 masing-masing bernilai 0,014 g/L.jam,  2,76 g/L dan 3,66 g/L. Hasil penelitian memperlihatkan pula bahwa waktu penambahan ALV sangat mempengaruhi pertumbuhan sel, dengan waktu penambahan yang terbaik adalah setelah pada jam ke-20.  Kata kunci: air limbah industri minyak kelapa sawit, polihidroksialkanoat (PHA), batch, Ralstonia eutropha JMP 134, asam lemak volatil (ALV)  

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