scholarly journals Chemically Enhanced Primary Sludge as an Anaerobic Co-Digestion Additive for Biogas Production from Food Waste

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 709 ◽  
Author(s):  
Xiaorong Kang ◽  
Yali Liu
Keyword(s):  
Chemical Oxygen Demand ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Mechanism Analysis ◽  
Primary Sludge ◽  
Biogas Yield ◽  
Batch Tests ◽  
Solids Removal

In order to overcome process instability and buffer deficiency in the anaerobic digestion of mono food waste (FW), chemically enhanced primary sludge (CEPS) was selected as a co-substrate for FW treatment. In this study, batch tests were conducted to study the effects of CEPS/FW ratios on anaerobic co-digestion (coAD) performances. Both soluble chemical oxygen demand (SCOD) and protease activity were decreased, with the CEPS/FW mass ratio increasing from 0:5 to 5:0. However, it was also found that the accumulation of volatile fatty acids (VFAs) was eliminated by increasing the CEPS/FW ratio, and that corresponding VFAs concentrations decreased from 13,872.97 to 1789.98 mg chemical oxygen demand per L (mg COD/L). In addition, the maximum value of cumulative biogas yield (446.39 mL per g volatile solids removal (mL/g VSsremoval)) was observed at a CEPS/FW ratio of 4:1, and that the tendency of coenzyme F420 activity was similar to biogas production. The mechanism analysis indicated that Fe-based CEPS relived the VFAs accumulation caused by FW, and Fe(III) induced by Fe-based CEPS enhanced the activity of F420. Therefore, the addition of Fe-based CEPS provided an alternative method for FW treatment.

scholarly journals Effect Of Alkaline Pre-Treatment On Cassava Pulp For Optimum Biogas Production

2019 ◽  
Vol 8 (2) ◽  
pp. 5919-5923
Keyword(s):  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Treatment Method ◽  
Batch Mode ◽  
Biogas Yield ◽  
Cassava Pulp ◽  
Soluble Chemical Oxygen Demand ◽  
Pre Treatment

(Being produced in vast quantity as one of by-product from cassava starch processing chains, cassava pulp has great potential for energy recovery by harnessing biogas through anaerobic digestion (AD). This study aims to enhance biogas production by comparative investigation in batch mode digestion. 5%TS w/v of cassava pulp mixed with mill effluent were pre-treated with 10 molar potassium hydroxide (KOH), sodium hydroxide (NaOH), and calcium hydroxide (Ca(OH)2) solution for 6 hours contact time. Effects of different alkaline pre-treatment on cassava substrate were assessed in total dissolved solid (TDS), soluble chemical oxygen demand (SCOD), Volatile Fatty Acids to Alkalinity ratio (VFA/TA), and reducing sugars. Daily accumulated biogas yield was taken as final indicator of the effect of different pre-treatment. KOH pre-treatment in pH 11 resulted highest dissolved solid 13.07 mg/L, and improved soluble chemical oxygen demand (SCOD) formation up to 75.61% (480,000 mg/L) than control substrate. The experiment revealed peak biogas production by KOH pre-treated substrate was found at day 6 after digestion executed, and achieved 546 ml. The finding proves out of different pre-treatment method applicable to cassava pulp, KOH pre-treatment could realistically increase biogas yield for cassava mills. Biogas production increased up to 101%, 92%, and 70% using KOH, Ca(OH)2 and NaOH respectively. However, when future provision to the technology for AD system and design is concerned, the choice of highly reactive alkali could lead to complication in the system.

Alkali pre-treatment of Sorghum Moench for biogas production

2013 ◽  
Vol 67 (9) ◽  
Author(s):  
Karina Michalska ◽  
Stanisław Ledakowicz
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Total Phenolic ◽  
Methane Generation ◽  
Pre Treatment ◽  
Alkali Hydrolysis ◽  
Almost All

AbstractThis work studies the influence of the alkali pre-treatment of Sorghum Moench — a representative of energy crops used in biogas production. Solutions containing various concentrations of sodium hydroxide were used to achieve the highest degradation of lignocellulosic structures. The results obtained after chemical pre-treatment indicate that the use of NaOH leads to the removal of almost all lignin (over 99 % in the case of 5 mass % NaOH) from the biomass, which is a prerequisite for efficient anaerobic digestion. Several parameters, such as chemical oxygen demand, total organic carbon, total phenolic content, volatile fatty acids, and general nitrogen were determined in the hydrolysates thus obtained in order to define the most favourable conditions. The best results were obtained for the Sorghum treated with 5 mass % NaOH at 121°C for 30 min The hydrolysate thus achieved consisted of high total phenolic compounds concentration (ca. 4.7 g L−1) and chemical oxygen demand value (ca. 45 g L−1). Although single alkali hydrolysis causes total degradation of glucose, a combined chemical and enzymatic pre-treatment of Sorghum leads to the release of large amounts of this monosaccharide into the supernatant. This indicates that alkali pre-treatment does not lead to complete cellulose destruction. The high degradation of lignin structure in the first step of the pre-treatment rendered the remainder of the biomass available for enzymatic action. A comparison of the efficiency of biogas production from untreated Sorghum and Sorghum treated with the use of NaOH and enzymes shows that chemical hydrolysis improves the anaerobic digestion effectiveness and the combined pre-treatment could have great potential for methane generation.

Anaerobic digestion of deproteinated cheese whey

1985 ◽  
Vol 52 (3) ◽  
pp. 457-467 ◽  
Author(s):  
Johannes De Haast ◽  
Trevor J. Britz ◽  
Johannes C. Novello ◽  
Emilige W. Verwey
Keyword(s):  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Fixed Bed ◽  
Oxygen Demand ◽  
Ammonia Level ◽  
Fixed Bed Reactor ◽  
Total Carbon ◽  
Ammonia Toxicity ◽  
Biogas Yield ◽  
Titration Curves

SUMMARYWhey and deproteinated whey preparations with different carbon: nitrogen (C/N) ratios ranging from 7·5 to 73 were digested anaerobically in a downflow stationary fixed-bed reactor at 35 °C with a hydraulic retention time of 5 d. Effluent and biogas parameters indicated that no decrease in digestion and stability occurred at the highest C/N ratio. Chemical oxygen demand (COD) removal averaged 88%, while volatile fatty acids were maintained at a low level (< 500 mg l–1). Biogas yield averaged 0·423 m3kg–1COD and the methane content of the biogas varied between 57 and 63%. Ammonia toxicity occurred at a C/N ratio of 7/5 in the substrate feed. Virtually no ammonia N was detected in the effluent when whey substrates with C/N ratios of 50 and 73 were fed. Titration curves showed that buffer intensities in the effluent were not affected by a decrease in ammonia level. A decrease in the biomass content of the effluent which occurred as a result of the increase in C/N ratio of the substrate did not cause any rate limiting effect on biogas production. The removal of protein from the whey caused a reduction in the ratio of COD: total carbon in the whey. On average 59% of the carbon in the substrate was converted to biogas.

Anaerobic baffled reactor treatment of biodiesel-processing wastewater with high strength of methanol and glycerol: reactor performance and biogas production

2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Darin Phukingngam ◽  
Orathai Chavalparit ◽  
Dararat Somchai ◽  
Maneerat Ongwandee
Keyword(s):  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Reactor Performance ◽  
Electron Microscopic ◽  
Anaerobic Baffled Reactor

AbstractBiodiesel-processing factories employing the alkali-catalyzed transesterification process generate a large amount of wastewater containing high amount of methanol, glycerol, and oil. As such, wastewater has high potential to produce biogas using anaerobic treatment. The aim of this research was to investigate the performance of an anaerobic baffled reactor for organic removal and biogas production from biodiesel wastewater. The effect of different organic loading rates, varying from 0.5 kg m−3 d−1 to 3.0 kg m−3 d−1 of chemical oxygen demand, was determined using three 22 L reactors, each comprising five separate compartments. Wastewater was pretreated with chemical coagulants to partially remove oil prior to experimentation. Results show that the anaerobic baffled reactor operated at 1.5 kg m−3 d−1 of chemical oxygen demand and ten days of hydraulic retention time provided the best removal efficiencies of 99 % of chemical oxygen demand, 100 % of methanol, and 100 % of glycerol. Increasing the organic loading rate over 1.5 kg m−3 d−1 of chemical oxygen demand led to excessive accumulation of volatile fatty acids thereby making the pH drop to a value unfavorable for methanogenesis. The biogas production rate was 12 L d−1 and the methane composition accounted for 64–74 %. Phase-separated characteristics revealed that the highest chemical oxygen demand removal percentage was achieved in the first compartment and the removal efficiency gradually decreased longitudinally. A scanning electron microscopic study indicated that the most predominant group of microorganisms residing on the external surface of the granular sludge was Methanosarcina.

scholarly journals Enhancement of Volatile Fatty Acids Production from Food Waste by Mature Compost Addition

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2986
Author(s):  
Yen-Keong Cheah ◽  
Joan Dosta ◽  
Joan Mata-Álvarez
Keyword(s):  
Fatty Acids ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Fermentation Broth ◽  
Oxygen Demand ◽  
Biological Pretreatment ◽  
Batch Tests ◽  
Production Improvement ◽  
Mature Compost ◽  
Total Ammonium

Food waste (FW) collected from a university canteen was treated in acidogenic fermenters to produce volatile fatty acids (VFA) under biological pretreatment with mature compost. Batch assays working at pH 6 revealed an increment of 9.0%, 7.9%, and 4.1% (on COD basis) of VFA concentration when adding 2.5%, 3.5%, and 4.5% w/w of mature compost, respectively, even though the volatile solids (VS) concentration of food waste was lower in the tests with increasing doses of mature compost. For batch tests at pH 7, this VFA generation improvement was lower, even though enhanced COD solubilization was recorded. Operating in semi-continuous conditions at 35 °C, pH of 6, and hydraulic retention time (HRT) of 3.5 days, the addition of 2.5% w/w of mature compost led to a VFA concentration up to 51.2 ± 12.3% more (on VS basis) when compared to a reference reactor without compost addition. Moreover, the percentage of butyric acid on VS basis in the fermentation broth working at a pH of 6 increased from up to 12.2 ± 1.9% (0% compost addition) to up to 23.5 ± 2.7% (2.5% compost addition). The VFA production was not improved when a higher percentage of mature compost was used (3.5% instead of 2.5% w/w), and it slightly decreased when mature compost addition was lowered to 1.5% w/w. When working at a pH of 7 in the semi-continuous fermenters with the addition of 2.5% w/w mature compost at an HRT of 3.5 days, an improvement of 79% and 104% of the VFA concentration (on VS basis) were recorded as compared to fermenters working at a pH of 6 with 2.5% and 0% w/w of mature compost addition, respectively. At a pH of 7, higher production of propionic and valeric acids was found with respect to the reactor working at a pH of 6. The effect of pH on VFA generation was estimated to have greater contribution than that of only biological pretreatment using mature compost. At a pH of 7, the VFA yield was higher for the fermenter working with 2.5% w/w mature compost but at a pH of 7 and HRT of 5 days, the effect of mature compost on VFA production improvement was lower than that obtained at a pH of 6. Moreover, higher solubilization in terms of soluble chemical oxygen demand and total ammonium was detected when biological pretreatment using mature compost was applied at both a pH of 6 and a pH of 7, which indicates enhanced hydrolysis in both conditions.

scholarly journals Effects of Hydrothermal Pretreatment and Hydrochar Addition on the Performance of Pig Carcass Anaerobic Digestion

2021 ◽  
Vol 12 ◽  
Author(s):  
Jie Xu ◽  
Hongjian Lin ◽  
Kuichuan Sheng
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Ammonia Concentration ◽  
Hydrothermal Pretreatment ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Liquid Products ◽  
Pig Carcasses

Proper disposal and utilization of dead pig carcasses are problems of public concern. The combination of hydrothermal pretreatment (HTP) and anaerobic digestion is a promising method to treat these wastes, provided that digestion inhibition is reduced. For this reason, the aim of this work was to investigate the optimal HTP temperature (140–180°C) for biogas production during anaerobic digestion of dead pigs in batch systems. In addition, the effects of hydrochar addition (6 g/L) on anaerobic digestion of pork products after HTP in continuous stirred tank reactors (CSTR) were determined. According to the results, 90% of lipids and 10% of proteins present in the pork were decomposed by HTP. In addition, the highest chemical oxygen demand (COD) concentration in liquid products (LP) reached 192.6 g/L, and it was obtained after 170°C HTP. The biogas potential from the solid residue (SR) and LP was up to 478 mL/g-VS and 398 mL/g-COD, respectively. A temperature of 170°C was suitable for pork HTP, which promoted the practical biogas yield because of the synergistic effect between proteins and lipids. Ammonia inhibition was reduced by the addition of hydrochar to the CSTR during co-digestion of SR and LP, maximum ammonia concentration tolerated by methanogens increased from 2.68 to 3.38 g/L. This improved total biogas yield and degradation rate of substrates, reaching values of 28.62 and 36.06%, respectively. The acetate content in volatile fatty acids (VFA) may be used as an index that reflects the degree of methanogenesis of the system. The results of the present work may also provide guidance for the digestion of feedstock with high protein and lipid content.

scholarly journals Biogas Generation from Sonicated Excess Sludge

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2127 ◽  
Author(s):  
Iwona Zawieja ◽  
Renata Włodarczyk ◽  
Mariusz Kowalczyk
Keyword(s):  
Sewage Sludge ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Calorific Value ◽  
Ultrasonic Field ◽  
Excess Sludge ◽  
Methane Fermentation ◽  
Biogas Yield ◽  
Yield Value

The article presents an analysis of the possibilities of biogas production in the process of methane fermentation of sonicated excess sludge. The greater the percentage of methane in biogas, the higher its calorific value. In order to increase the intensity of biogas production containing approximately 70% of methane, sewage sludge is disintegrated. In particular, excess sludge formed as a result of advanced wastewater treatment by the activated sludge method shows low biodegradability. The study aim was to examine the effect of the ultrasonic field disintegration of excess sludge on biogas production. As a result of subjecting the sludge to disintegration by ultrasonic field, there was an increase in the digestion degree of sewage sludge. In the methane fermentation process of modified sludge, an increase of the biogas yield was noted, which confirmed the supportive action of ultrasonic field on the excess sludge biodegradation. In the case of disintegration of excess sludge by ultrasonic field, for the ultrasonic field intensity value of 4.3 W cm−2 and a sonication time equal to 300 s, the highest values of soluble chemical oxygen demand (SCOD), total organic carbon (TOC), and volatile fatty acids (VFAs) concentrations were obtained. In the process of conventional methane fermentation, biogas yield value was 0.303 L g VSS−1, while in the process of methane fermentation of sonicated excess sludge, the value 0.645 L g VSS−1.

scholarly journals Biogas Production Using Slaughterhouse Wastewater Co-digested with Domestic Sludge

2019 ◽  
Vol 8 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Salah S.B. Dababat ◽  
Hafez Q. Shaheen
Keyword(s):  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Final Concentration ◽  
Primary Sludge ◽  
Slaughterhouse Wastewater ◽  
Biogas Yield ◽  
Digestion Process ◽  
Lab Experiments ◽  
Before And After ◽  
Batch Bioreactors

  The paper investigates producing biogas using Co-digestion of slaughterhouse wastewater (SHW) with primary sludge (PS). Lab experiments were executed at mesophilic condition (35±2°C). Two experiments were performed; the first in a 2000 ml vessel and the second in 600 ml serum bottles, both to mimic batch bioreactors. Among others, acidity (pH), alkalinity (ALK), and volatile fatty acids (VFA) were measured before and after the digestion process. The daily biogas and methane production were also measured. The experiments showed that Co-digestion achieved maximum biogas yield at 499.8 Nml Biogas/g VS fed. The biogas yield for PS and SHW were 411.5 Nml biogas /g VS fed and 433.8 Nml biogas /g VS fed respectively. CH4 yield from the Co-digestion was the highest compared to digest SHW separately. This proves the occurrence of inhibition in methanogenesis activity. The VFA final concentration was higher than the initial concentration for digest SHW.

scholarly journals Biogas potential of organic waste onboard cruise ships — a yet untapped energy source

2021 ◽  
Author(s):  
Kai Schumüller ◽  
Dirk Weichgrebe ◽  
Stephan Köster
Keyword(s):  
Energy Source ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Food Waste ◽  
Energy Demand ◽  
Organic Waste ◽  
Biogas Production ◽  
Biogas Yield ◽  
Cruise Ships ◽  
Detailed Presentation

AbstractTo tap the organic waste generated onboard cruise ships is a very promising approach to reduce their adverse impact on the maritime environment. Biogas produced by means of onboard anaerobic digestion offers a complementary energy source for ships’ operation. This report comprises a detailed presentation of the results gained from comprehensive investigations on the gas yield from onboard substrates such as food waste, sewage sludge and screening solids. Each person onboard generates a total average of about 9 kg of organic waste per day. The performed analyses of substrates and anaerobic digestion tests revealed an accumulated methane yield of around 159 L per person per day. The anaerobic co-digestion of sewage sludge and food waste (50:50 VS) emerged as particularly effective and led to an increased biogas yield by 24%, compared to the mono-fermentation. In the best case, onboard biogas production can provide an energetic output of 82 W/P, on average covering 3.3 to 4.1% of the total energy demand of a cruise ship.

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