Mesophilic Anaerobic Co-Digestion of Fruit and Vegetable Waste and Domestic Primary Sewage Sludge: Performance and Kinetic

Wastes such as fruit and vegetable waste and sewage sludge are not easy to be manage because of their chemical and physical properties. These waste also high putrescible. Recent years, landfill disposal is no longer a sustainable way for waste management as the area of landfill has become more limited. Therefore, new approach such anaerobic digestion should be considered for these wastes. However, the mono-digestion has a drawback, including lesser methane yield due to the substrate characteristics. To overcome this problem, the co-digestion is introduced, in which two or more substrate feed to the digester concurrently. This study aims to evaluate the performance and the kinetics from the co-digestion of fruit and vegetable waste with domestic primary sewage sludge. In this study, the bio-methane potential assay (BMP) at batch mode is conducted. The BMP assay is carried out at the inoculum to substrate (I/S) ratio of 2.0 at 37oC. The kinetics analysis was included using Modified Gompertz Modelling. The characteristics study showed that the complex organic compounds existed in form of particulate mostly. The methane production was stopped at day 12 resulted in the ultimate methane yield of 1149.50 mLCH4/gVS. In addition, the methane kinetics parameter observed from laboratory work slightly   different from what was observed from the modelling

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

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  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

Sample Biochemical Methane Potential from the Digestion of Domestic Mixed Sewage Sludge in Batch Tests

Biochemical methane potential (BMP) is a standard test to assess the biogas (including methane) production from the anaerobic digestion of any organic waste. In many anaerobic digestions of sewage sludge, the inoculum to substrate ratio and mixing were variable to take into consideration for efficient performance. However, the organic content in sewage sludge varied due to the composition of the raw wastewater being treated and the treatment condition. This study is focused on the methane production from the digestion of domestic mixed sewage sludge in the batch reactor at different organic contents. Biochemical methane potential (BMP) was conducted at the inoculum to substrate ratio (I/S) ratio of 2:0, each with different organic content. On the termination day of the BMP assay, the sample from each BMP reactor was tested for pH, and alkalinity to determine the status of the anaerobic process. Results showed that the anaerobic process was stable since the pH remained in the pH range which is suitable for the anaerobic process to take place. The anaerobic process was also confirmed stabled as indicated by low value (< 0.3) of intermediate alkalinity to partial alkalinity ratio (IA/PA). The ultimate methane yield was 588.3 ml CH4/g VS at the organic content of 0.52 and 1244.5 ml CH4/g VS at the organic content of 0.68 respectively. For the organic content of 0.68, the maximum methane production rate constant  was 13.97 mL CH4/g VS /hr. For the case of lower organic content, the maximum methane production rate constant was 6.41 mL CH4/g VS /hr. However, the lag phase of the methane yield curve for both organic content was less than one (1) day, showing the good biodegradability of domestic mixed sewage sludge.

Assessment of Specific Methanogenic Activity from Cow Dung

The specific methanogenic activity (SMA) is a test to measure the producing potential of an anaerobic bacteria until it’s allowing a relevant organic loading rates to be applied for a selected substrate. Commonly, acetate is used as substrate for the SMA test. Anaerobic bacteria were mostly taken from an anaerobic digester and cow dung was also implemented as a source of an anaerobic bacteria. However, the results of SMA of cow dung was less reported. Therefore, this study is initiated to determine the potential of methane production from the cow dung by using the SMA test. Prior the SMA test, the cow dung was characterized for solids where the results showed that the cow dung is having 12.00 g L-1 for total solid and 10.50 g L-1 for volatile solid. The SMA test was conducted at mesophilic condition by using an automatic methane potential system test (AMPTS II) and the SMA of the cow dung was found as 0.04 in unit g COD-CH4 g-1VS-1d-1. The significance of this research is to determine the anaerobic bacteria potential of cow dung for use in the anaerobic digestion process, which offers numerous advantages for manufacturing, particularly in industrial applications such as methane production (fuel)

Assessment of Specific Methanogenic Activity from Cow Dung

The specific methanogenic activity (SMA) is a test to measure the producing potential of an anaerobic bacteria until it’s allowing a relevant organic loading rates to be applied for a selected substrate. Commonly, acetate is used as substrate for the SMA test. Anaerobic bacteria were mostly taken from an anaerobic digester and cow dung was also implemented as a source of an anaerobic bacteria. However, the results of SMA of cow dung was less reported. Therefore, this study is initiated to determine the potential of methane production from the cow dung by using the SMA test. Prior the SMA test, the cow dung was characterized for solids where the results showed that the cow dung is having 12.00 g L-1 for total solid and 10.50 g L-1 for volatile solid. The SMA test was conducted at mesophilic condition by using an automatic methane potential system test (AMPTS II) and the SMA of the cow dung was found as 0.04 in unit g COD-CH4 g-1VS-1d-1. The significance of this research is to determine the anaerobic bacteria potential of cow dung for use in the anaerobic digestion process, which offers numerous advantages for manufacturing, particularly in industrial applications such as methane production (fuel)

Biodegradability of Fruit and Vegetable Waste (FVW)

This chapter reviews one of organic fraction of municipal solid waste, which is food waste. It covers the food waste generation rate, environmental issues in managing food waste and food waste disposal /treatment method. The review on the fruit and vegetable waste (FVW) is included in the term of the characterization. This chapter also includes the FVW stabilization method and the FVW digestibility. The methane yield observed from the batch biomethane potential tests (BMP) and the modelling analysis using Modified Gompertz to examine kinetic parameters of biodigestibility of FVW are presented. In addition, FVW is having organic matter as indicated by higher TS/VS ratio, make it is a preferable substrate (sole substrate) for anaerobic digestion

Methane Production from the Digestion of Thermally Treated Food Waste at 80°C

Food waste is the most suitable feedstock for anaerobic digestion. However, methane yield from the digestion of food waste is low. Therefore thermal pretreatment serves as the best solution. Also, the effect of thermal pretreatment on food waste (Malaysian dietary) before anaerobic digestion has low documentation. Hence this research aims to analyze the methane production and its kinetics from the digestion of thermally treated food waste. The result showed that thermal treatment improves the bioavailability of food waste, subsequently improve the methane production of food waste. The ultimate methane yield for thermally treated food waste at 80°C was 883.08 CH4/gVS higher than untreated food waste. The kinetic parameters observed from Modified Gompertz modeling were slightly lower from the laboratory data for both substrates. Thus, thermal pretreatment undoubtedly improved the anaerobic digestion of food waste

Low Thermal Pretreatment as Method for Increasing the Bioavailability of Organic Matters in Domestic Mixed Sludge

In practice, primary and secondary sludge are fed into anaerobic digestion. However, the microbial cell exists in secondary sludge are an unfavorable substrate for biodegradation. Thermal pretreatment is proved to increase the bioavailability of organic and improve the biodegradation subsequently. During low thermal pretreatment, both intracellular (within the microbial cell) and extracellular (within the polymeric network) materials were extracted. This process increases the bioavailability meaning that organic compounds are accessible to the microorganisms for their degradation. This research aims to investigate the effect of thermal pretreatment on domestic mixed sludge disintegration. Domestic mixed sludge was thermally treated at 70°C for various holding times. The pre-thermally treated domestic mixed sludge was measured for protein and carbohydrates following the Lowry Method, and Phenol-Sulphuric Acid Method respectively. DR 6000 UV-Vis spectrophotometer, DRB200 Reactor (digester) and COD vial (TNT plus 822) were used for COD determination, based on Reactor Digestion Method approved by USEPA. The results showed that the organic matter in domestic mixed sludge is efficiently solubilised during thermal treatment organic matter. The higher soluble yield for each monitored parameter determined in this study indicated that low thermal pretreatment improve bioavailability

Low Thermal Pretreatment as Method for Increasing the Bioavailability of Organic Matters in Domestic Mixed Sludge

In practice, primary and secondary sludge are fed into anaerobic digestion. However, the microbial cell exists in secondary sludge are an unfavorable substrate for biodegradation. Thermal pretreatment is proved to increase the bioavailability of organic and improve the biodegradation subsequently. During low thermal pretreatment, both intracellular (within the microbial cell) and extracellular (within the polymeric network) materials were extracted. This process increases the bioavailability meaning that organic compounds are accessible to the microorganisms for their degradation. This research aims to investigate the effect of thermal pretreatment on domestic mixed sludge disintegration. Domestic mixed sludge was thermally treated at 70°C for various holding times. The pre-thermally treated domestic mixed sludge was measured for protein and carbohydrates following the Lowry Method, and Phenol-Sulphuric Acid Method respectively. DR 6000 UV-Vis spectrophotometer, DRB200 Reactor (digester) and COD vial (TNT plus 822) were used for COD determination, based on Reactor Digestion Method approved by USEPA. The results showed that the organic matter in domestic mixed sludge is efficiently solubilised during thermal treatment organic matter. The higher soluble yield for each monitored parameter determined in this study indicated that low thermal pretreatment improve bioavailability