Enhancement of Methane Production in Anaerobic Digestion of Food Waste using Thermal Pretreatment

Anaerobic digestion (AD) is an energy production process and food waste is a potential feedstock. The main biochemical reactions are Hydrolysis, Acidogenesis, Acetogenesis, and Methanogenesis. The hydrolysis step acts as the rate-limiting reaction and the pretreatment of the feedstocks can be used to support this step. In this research, thermal pretreatment was used as a potential method for food waste pretreatment. Six different pretreatment conditions were used: two different temperatures (80oC and 100oC) and three different pretreatment times (30, 60, and 90 min). The Bio-Methane Potential (BMP) test was conducted using 120 mL serum bottles for 20 days to determine the most suitable pretreatment conditions. An experiment was also conducted at the selected optimal conditions (80oC for 90 min) using a small-scale bioreactor against the control with a NaHCO3 buffer solution. The highest Soluble Chemical Oxygen Demand (SCOD) was observed at 100oC for 90 min. The optimal pretreatment was selected as 80oC for 90 min, which produced 14.75 mL/g VS of methane while the control produced 8.64 mL/g VS in BMP test. After a few days, the methane production started to slow down due to a decrease in pH. When a buffer was added, a specific methane yield of 120.13 mL/g VS was observed in the small-scale bioreactor. This was an 11.24% increase compared to the buffered control without thermal pretreatment. In conclusion, thermal pretreatment has a potential to enhance the AD but it is economical to use with less biodegradable waste than food waste.

Download Full-text

Comparison of the impacts of thermal pretreatment on waste activated sludge using aerobic and anaerobic digestion

Water Science & Technology ◽

10.2166/wst.2018.458 ◽

2018 ◽

Vol 78 (8) ◽

pp. 1772-1781 ◽

Cited By ~ 1

Author(s):

Hyungjun (Brian) Jo ◽

Wayne Parker ◽

Peiman Kianmehr

Keyword(s):

Anaerobic Digestion ◽

Activated Sludge ◽

Oxygen Demand ◽

Waste Activated Sludge ◽

Thermal Pretreatment ◽

Decay Products ◽

Anaerobic Biodegradability ◽

Pretreatment Conditions ◽

The Impact ◽

Aerobic And Anaerobic

Abstract A range of thermal pretreatment conditions were used to evaluate the impact of high pressure thermal hydrolysis on the biodegradability of waste activated sludge (WAS) under aerobic and anaerobic conditions. It was found that pretreatment did not increase the overall extent to which WAS could be aerobically biodegraded. Thermal pretreatment transformed the biodegradable fraction of WAS (XH) to readily biodegradable chemical oxygen demand (COD) (SB) (16.5–34.6%) and slowly biodegradable COD (XB) (45.8–63.6%). The impact of pretreatment temperature and duration on WAS COD fractionation did not follow a consistent pattern as changes in COD solubilization did not correspond to the observed generation of SB through pretreatment. The pretreated WAS (PWAS) COD fractionations determined from aerobic respirometry were employed in anaerobic modeling and it was concluded that the aerobic and anaerobic biodegradability of PWAS differed. It was found that thermal pretreatment resulted in as much as 50% of the endogenous decay products becoming biodegradable in anaerobic digestion. Overall, it was concluded that the COD fractionation that was developed based upon the aerobic respirometry was valid. However, it was necessary to implement a first-order decay process that reflected changes in the anaerobic biodegradability of the endogenous products through pretreatment.

Download Full-text

Enhancement anaerobic digestion and methane production from kitchen waste by thermal and thermo-chemical pretreatments in batch leach bed reactor with down flow

Research in Agricultural Engineering ◽

10.17221/16/2017-rae ◽

2018 ◽

Vol 64 (No. 3) ◽

pp. 128-135 ◽

Cited By ~ 1

Author(s):

Radmard Seyed Abbas ◽

Alizadeh Hossein Haji Agha ◽

Seifi Rahman

Keyword(s):

Anaerobic Digestion ◽

Microwave Irradiation ◽

Methane Production ◽

Biogas Production ◽

Oxygen Demand ◽

Lag Phase ◽

Kitchen Waste ◽

Gompertz Equation ◽

Chemical Pretreatments ◽

Pretreatment Conditions

The effects of thermal (autoclave and microwave irradiation (MW)) and thermo-chemical (autoclave and microwave irradiation – assisted NaOH 5N) pretreatments on the chemical oxygen demand (COD) solubilisation, biogas and methane production of anaerobic digestion kitchen waste (KW) were investigated in this study. The modified Gompertz equation was fitted to accurately assess and compare the biogas and methane production from KW under the different pretreatment conditions and to attain representative simulations and predictions. In present study, COD solubilisation was demonstrated as an effective effect of pretreatment. Thermo-chemical pretreatments could improve biogas and methane production yields from KW. A comprehensive evaluation indicated that the thermo-chemical pretreatments (microwave irradiation and autoclave- assisted NaOH 5N, respectively) provided the best conditions to increase biogas and methane production from KW. The most effective enhancement of biogas and methane production (68.37 and 36.92 l, respectively) was observed from MW pretreated KW along with NaOH 5N, with the shortest lag phase of 1.79 day, the max. rate of 2.38 l·day<sup>–1</sup> and ultimate biogas production of 69.8 l as the modified Gompertz equation predicted.

Download Full-text

Anaerobic Co-Digestion of Food Waste and Thermal Pretreated Waste Activated Sludge: Synergetic Effect and Energy Assessment

10.21203/rs.3.rs-1036515/v1 ◽

2021 ◽

Author(s):

Jian Zhang ◽

Peng Gan ◽

Ru-yi Wang ◽

Tian Xie ◽

Yang Liu ◽

...

Keyword(s):

Anaerobic Digestion ◽

Activated Sludge ◽

Food Waste ◽

Methane Production ◽

Synergetic Effect ◽

Gompertz Model ◽

Waste Activated Sludge ◽

Thermal Pretreatment ◽

Energy Assessment ◽

Modified Gompertz Model

Abstract Thermal pretreatment was an effective method to improve the anaerobic digestion of waste activated sludge. However its application in China was still hindered by the high energy demand. In order to balance the energy consumption of sludge thermal pretreatment integrated with anaerobic digestion, food waste was introduced as co-substrate to achieve an energy self-sustainable sludge treatment system. Anaerobic biodegradability test was performed using thermal pretreated sludge and food waste in order to clarify the kinetics and mechanism of co-digestion, especially the synergetic effect on specific methane yield. The prominent synergetic effect was an initial acceleration of cumulative methane production by 20.7- 23.8% observed during the first 15 days, and the cumulative methane production of feedstock can be calculated proportionately from its composition. Between the evaluated models, modified Gompertz model presented a better agreement of the experimental results and it was able to describe the synergetic effect, assessed by the relative deviation between theoretical estimation and the experimental results of co-digestion tests. This feature made modified Gompertz model a suitable tool for methane production prediction of mono- and co-digestion. Energy assessment shown that co-digestion with food waste was a sustainable solution to maintain the integration of thermal pretreatment and anaerobic digestion energy neutral or even positive. Besides, the performance of sludge dewatering was a crucial factor for the energy balance.

Download Full-text

The Performance Evaluation on Co-Digestion of Domestic Sewage Sludge and Food Waste for Methane Yield and Kinetics Analysis

International Journal of Integrated Engineering ◽

10.30880/ijie.2021.13.03.004 ◽

2021 ◽

Vol 13 (3) ◽

Author(s):

Siti Mariam Sulaiman ◽

◽

Roslinda Seswoya ◽

Keyword(s):

Anaerobic Digestion ◽

Sewage Sludge ◽

Food Waste ◽

Methane Production ◽

Test System ◽

Domestic Sewage ◽

Methane Yield ◽

Methane Potential ◽

Methane Production Rate ◽

Bmp Test

Sewage sludge and food waste; are organic wastes suitable for the anaerobic digestion. However, the digestion of sewage sludge and food waste as solely substrate is having a drawback in term of methane yield. Therefore, many researchers combined these two wastes as a co-substrate and used in co-digestion. This study focused to evaluate the anaerobic co-digestion of domestic sewage sludge (in form of primary and secondary sewage sludge) with food waste under mesophilic temperature in a batch assay. Two series of batch biochemical methane potential (BMP) test were conducted using the Automatic Methane Potential Test System (AMPTS II). Each set are labelled with BMP 1(PSS:FW) and BMP 2 (SSS:FW). The BMP tests were monitored automatically until the methane production is insignificant. Using the data observed in the laboratory, the kinetic paremeters were calculated. Also, the First-order and Modified Gompertz modeling were included to predict the anaerobic digestion performance. Finding showed that BMP 1(PSS:FW) have better performance with respect to the higher ultimate methane yield and methane production rate as compared to BMP 2 (SSS:FW). Besides, the kinetic parameters from laboratory work and modeling were slightly different. In which the kinetic paremetes from modelling is lesser. However, both modelling are well fitted to the experimental data with high correlation coefficient, R2 ranged from 0.993 to 0.997.

Download Full-text