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.

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 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.

Effect of Hydrothermal Pretreatment on Volatile Fatty Acids Production from Thickened Waste Activated Sludge

2019 ◽  
Vol 13 (2) ◽  
pp. 591-604 ◽  
Author(s):  
Farokh laqa Kakar ◽  
Ehssan Hosseini Koupaie ◽  
Ahmed Shabir Razavi ◽  
Hisham Hafez ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge

Riboflavin boosts fermentative valeric acid generation from waste activated sludge

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3962-3969
Author(s):  
Binfang Shi ◽  
Jingang Huang ◽  
Zhenjiang Yin ◽  
Wei Han ◽  
Shanshan Qiu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Acid Production ◽  
Volatile Fatty Acids ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Valeric Acid ◽  
Waste Activated Sludge ◽  
Acid Generation

Fermentative valeric acid production is a promising way to recycle valuable resources from waste activated sludge (WAS). This study investigated the feasibility of using riboflavin (RF) to enhance volatile fatty acids (VFAs) production, especially valeric acid production from WAS coupled with solid reduction. The results indicated that RF (0.5 mM) promoted the VFAs production by up to 41.0%. Valeric acid accounted for the most abundance within the VFAs components. When RF dosages were 0.05 to 5.0 mM in the WAS fermentation systems, the chemical oxygen demand fractions of valeric acid to the total VFAs were 41.0% to 62.8%, which were much higher than those using other chemical supplements. Moreover, RF enhanced the reduction of mixed liquor volatile suspended solids (MLVSS). When RF dosage was 0.2 mM, MLVSS reduction achieved a maximum at 47.4%, compared to that in the RF-free control (33.9% reduction). Riboflavin in this study was considered as a feasible chemical to enhance the fermentative valeric acid generation coupled to MLVSS reduction, realizing the reduction of solids and the reutilization of valuable resources from WAS.

Effect of Aeration Rate on the Hydrolysis and Acidification of Waste Activated Sludge in Thermophilic Aerobic Conditions

2013 ◽  
Vol 664 ◽  
pp. 111-116
Author(s):  
Ya Nan Hou ◽  
Chun Xue Yang ◽  
Ai Juan Zhou ◽  
Ai Jie Wang
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Ventilation Rate ◽  
Aeration Rate ◽  
Waste Activated Sludge ◽  
Digestion Process ◽  
Hydrolysis Process ◽  
Soluble Chemical Oxygen Demand

This study investigated the effect of aeration rates on the hydrolysis process of Waste Activated Sludge (WAS) with thermophilic aerobic microbes and explained by the change of solubilization of lipids, carbohydrates and proteins in sludge under different aeration rates (0.03 vvm, 0.05 vvm, 0.07 vvm, 0.09 vvm, 0.11 vvm). The results revealed that with the increase of aeration rate, the accumulation of volatile fatty acids (VFAs) in the treated sludge was decreased. Only 2 142 mg COD/L was accumulated at the ventilation rate of 0.11 vvm, while the highest accumulation which was 4 088 mg/L at the ventilation rate of 0.05 vvm. Further investigation showed that under optimal aeration rate which was 0.05 vvm, theromophilic aerobic microbes facilitated the organism hydrolysis and increased the biodegradability of WAS significantly. The concentration of carbohydrates was improved remarkably from 70 mg COD/L to 560 mg COD/L compared with the control (the process without aeration) at 65°C. Meanwhile, the concentration of protein was increased stably due to the high activity of protease, and reached the peak of 1 320 mg COD/L after 72h, then decline at the later period. The maximal soluble chemical oxygen demand (SCOD) was 5 600 mg/L and VFAs was 4 088 mg COD/L, which would be beneficial to the followed digestion process. Therefore, appropriate aeration is efficient to improve the accumulation of soluble organic matters and VFAs in WAS.

scholarly journals Alkaline solubilisation of waste activated sludge (WAS) for soluble organic substrate – (SCOD) production / Tworzenie się rozpuszczalnego substratu organicznego podczas zasadowego rozpuszczania osadów ściekowych

2015 ◽  
Vol 41 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Jan Suschka ◽  
Eligiusz Kowalski ◽  
Jerzy Mazierski ◽  
Klaudiusz Grübel
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Construction Material ◽  
Oxygen Demand ◽  
Organic Substrate ◽  
Waste Activated Sludge ◽  
Condition Effect ◽  
Hydrolysis Process ◽  
Soluble Chemical Oxygen Demand

Abstract Improving the effects of hydrolysis on waste activated sludge (WAS) prior to anaerobic digestion is of primary importance. Several technologies have been developed and partially implemented in practice. In this paper, perhaps the simplest of these methods, alkaline solubilization, has been investigated and the results of hydrolysis are presented. An increase to only pH 8 can distinctively increase the soluble chemical oxygen demand (SCOD), and produce an anaerobic condition effect favorable to volatile fatty acids (VFA) production. Further increases of pH, up to pH 10, leads to further improvements in hydrolysis effects. It is suggested that an increase to pH 9 is sufficient and feasible for technical operations, given the use of moderate anti-corrosive construction material. This recommendation is also made having taken in consideration the option of using hydrodynamic disintegration after the initial WAS hydrolysis process. This paper presents the effects of following alkaline solubilization with hydrodynamic disintegration on SCOD

scholarly journals THE EFFECT OF HYDROTHERMAL PRETREATMENT ON THE ANAEROBIC DIGESTION OF THICKENED WASTE ACTIVATED SLUDGE AND SOURCE SEPARATED ORGANICS

2021 ◽  
Author(s):  
Ahmad Shabir Razavi
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Pretreatment Condition ◽  
Wide Range ◽  
Biomethane Production ◽  
Pretreatment Conditions ◽  
The Impact ◽  
Severity Indexes

The objective of this study was to evaluate the impact of hydrothermal pretreatment of source separated organics (SSO) and thickened waste activated sludge (TWAS) on the solubilization and biomethane production. The feedstocks went through 15 different conditions in a wide range of temperature (150-240°C), retention time (5-30) min and severity indexes (3-5). The result of the study revealed that the effect of hydrothermal pretreatment can vary based on the feedstock primary properties and the optimum pretreatment condition. In this study, the optimum pretreatment conditions for highest solubilization and solid reduction of the SSO were 220°C and 10 minutes retention time, however, for highest methane production, it was 190°C for 20 minutes. In case of TWAS, the result revealed that the maximum biomethane production was achieved at pretreatment conditions of 160°C and 20 min, while, the highest solubilization and solid reduction was observed in 220°C and 10 minutes retention time.

scholarly journals Biomethane production improvement by hydrothermal pretreatment of thickened waste activated sludge

2020 ◽  
Author(s):  
Ahmad Shabir Razavi ◽  
Farokhlaqa Kakar ◽  
Ehssan Hosseini Koupaie ◽  
Hisham Hafez ◽  
Elsayed Elbeshbishy
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Hydrothermal Pretreatment ◽  
Effect Of Temperature ◽  
Waste Activated Sludge ◽  
Pretreatment Condition ◽  
Production Improvement ◽  
Biomethane Production ◽  
Pretreatment Conditions ◽  
The Impact

Abstract This study evaluated the impact of hydrothermal pretreatment on thickened waste activated sludge (TWAS) for solubilization enhancement and biomethane production improvement through the mesophilic anaerobic digestion process. In order to assess the effect of temperature, retention time and severity index (SI) of the hydrothermal pretreatment, TWAS was exposed to fifteen different pretreatment condition within a combination of 10 different pretreatment temperature range (150–240 °C), five different retention time (5–30 min) and five different severity indexes (SI = 3, 3.5, 4, 4.5 and 5). The solubilization enhancement was observed in all hydrothermally pretreated samples with the highest solubilization efficiency of 49% in pretreatment condition of 200 °C and 10 min retention time within the corresponding SI = 4. Biomethane production was not improved in all fifteen pretreatment conditions, pretreatment with SI beyond 4 decreased the biodegradability of TWAS. The highest biomethane production was observed in the pretreatment condition of 170 °C and 10 min by 40% increase compared to non-pretreated TWAS.

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