Application of enzymes in anaerobic digestion

2007 ◽  
Vol 56 (10) ◽  
pp. 29-35 ◽  
Author(s):  
G. Bochmann ◽  
T. Herfellner ◽  
F. Susanto ◽  
F. Kreuter ◽  
G. Pesta
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Economic Value ◽  
Spent Grain ◽  
Stable Performance ◽  
Pre Treatment ◽  
Ssf Process ◽  
Hydrolysis Of ◽  
Enzyme Application

Owing to the very low economic value of brewer's spent grains, its utilisation for biogas production is very promising. The hydrolysis of ligno-cellulose is the rate limiting step in anaerobic digestion. Enzymatic pre-treatment promotes the hydrolysis of ligno-cellulose, breaking it down to lower molecular weight substances which are ready to be utilised by the bacteria. A cheap raw multi-enzyme produced by a solid state fermentation (SSF) process is a good substitute for expensive conventional enzyme. The SSF enzyme application to spent grain has been investigated by carrying out enzymatic solubility tests, hydrolytic experiments and two-step anaerobic fermentation of spent grain. Gas chromatograph analysis was conducted to quantify fatty acids concentrations, while CH4, CO2, O2, H2 and H2S were measured to determine biogas quality by means of a gas analyser. DS, oDS, pH were also measured to analyse the anaerobic digestion. The result shows that enzyme application promotes the hydrolysis of ligno-cellulose, indicated by higher enzymatic solubility and fatty acid concentration in a hydrolytic bioreactor. Moreover, biogas production is also increased. The quality of the gases produced is also enhanced. Since the anaerobic digestion can be operated in a stable performance, it can also be concluded that SSF enzyme is compatible with anaerobic digestion.

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.

Influence of Ultrasound on the Synthesis of Biogas During Disposal of Beer Spent Grain

2021 ◽  
pp. 33-38
Author(s):  
Владимир Владимирович Житков ◽  
Борис Николаевич Федоренко
Keyword(s):  
Anaerobic Digestion ◽  
Energy Production ◽  
Biogas Production ◽  
Organic Substances ◽  
Ultrasonic Pretreatment ◽  
Biogas Yield ◽  
Spent Grains ◽  
Efficient Resource ◽  
Spent Grain ◽  
Environmentally Friendly Process

Ультразвуковая предварительная обработка считается экологически чистым процессом для повышения биоразлагаемости органических веществ при анаэробном сбраживании. Однако количество потребляемой энергии во время предварительной обработки является проблемой, особенно в тех случаях, когда производство энергии является основной целью биогазовой установки. Основной целью настоящего исследования работы было изучение эффективности ультразвуковой предварительной обработки для увеличения производства биогаза из отходов пивоваренного производства - пивной дробины. Результаты показали, что применение частоты 40 кГц при температуре 40 °С соответственно привело к увеличению выхода биогаза на 83%. Методология показала положительный результат в отношении содержания метана и скорости производства биогаза. Использование ультразвуковой предварительной обработки в отношении пивоваренной дробины для производства биогаза, по-видимому, позволяет решить проблемы не только эффективной утилизации пивоваренных отходов, но и создать экономически эффективный ресурс возобновляемой энергии на пивоваренном или аффилированном с ним производстве. Ultrasonic pretreatment is considered an environmentally friendly process to increase the biodegradability of organic substances during anaerobic digestion. However, the amount of energy consumed during pretreatment is a problem, especially in cases where energy production is the main purpose of the biogas plant. The main purpose of this study was to study the effectiveness of ultrasonic pretreatment to increase the production of biogas from brewing waste - brewer's grains. The results showed that the use of a frequency of 40 kHz at a temperature of 40 °C, respectively, led to an increase in the biogas yield by 83%. The methodology showed a positive result in terms of methane content and biogas production rate. The use of ultrasonic pretreatment for brewing spent grains for biogas production seems to solve the problems of not only efficient disposal of brewing waste, but also to create an economically efficient resource of renewable energy in brewing or its affiliated production.

scholarly journals Opportunity of Biogas Production from Solid Organic Wastes through Anaerobic Digestion

2018 ◽  
Vol 65 ◽  
pp. 05025 ◽  
Author(s):  
Sagor Kumar Pramanik ◽  
Fatihah Binti Suja ◽  
Biplob Kumar Pramanik ◽  
Shahrom Bindi Md Zain
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Nutrient Balance ◽  
Organic Wastes ◽  
Organic Loading Rate ◽  
Biogas Yield ◽  
Carbon And Nitrogen ◽  
Potential Risks ◽  
Nitrogen Ratio ◽  
Pre Treatment

Solid organic wastes create potential risks to environmental pollution and human health due to the uncontrolled discharge of huge quantities of hazardous wastes from numerous sources. Now-a-days, anaerobic digestion (AD) is considered as a verified and effective alternative compared to other techniques for treating solid organic waste. The paper reviewed the biological process and parameters involved in the AD along with the factors could enhance the AD process. Hydrolysis is considered as a rate-limiting phase in the complex AD process. The performance and stability of AD process is highly influenced by various operating parameters like temperature, pH, carbon and nitrogen ratio, retention time, and organic loading rate. Different pre-treatment (e.g. mechanical, chemical and biological) could enhance the AD process and the biogas yield. Co-digestion can also be used to provide suitable nutrient balance inside the digester. Challenges of the anaerobic digestion for biogas production are also discussed.

Effect of Ultrasonic Pretreatment for the Anaerobic Digestion of Sewage Sludge

2012 ◽  
Vol 531 ◽  
pp. 528-531 ◽  
Author(s):  
Na Wei
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
High Concentration ◽  
Ultrasonic Pretreatment ◽  
Soluble Chemical Oxygen Demand ◽  
Pre Treatment ◽  
Settling Characteristics

Anaerobic digestion is an economic and environmentally friendly technology for treating the biomass material-sewage sludge, but has some limitations, such as the low efficient biogass production. In this paper ultrasound was proposed as pre-treatment for effective sludge anaerobic digestion. Sludge anaerobic digestion experiments with ultrasonic pretreatment was investigated. It can be seen that this treatment effectively leaded to the increase of soluble chemical oxygen demand(SCOD) and volatile fatty acids(VFA)concentration. High concentration of VFA leaded to a increase in biogas production. Besides, the SV of sludge was reduced and the settling characteristics of sludge was improved after ultrasonic pretreatment. It can be concluded that sludge anaerobic digestion with ultrasonic pretreatment is an effective method for biomass material transformation.

Effect of a Cellulose-Degrading Strain on Anaerobic Fermentation of Corn Straw

2011 ◽  
Vol 356-360 ◽  
pp. 2510-2514 ◽  
Author(s):  
Ming Fen Niu ◽  
Sai Yue Wang ◽  
Wen Di Xu ◽  
An Dong Ge ◽  
Hao Wang
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Methane Production ◽  
Volatile Fatty Acids ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Corn Straw ◽  
High Efficient ◽  
Important Significance ◽  
Strong Capacity

In order to improve the rate of degradation of cellulose in corn straw, the study has an important significance that compost corn straw with inoculating high-efficient microbe agents. The experiment inoculated a cellulose-degrading strain F2 which was screened from compost into compost pretreatment, the VS of corn straw reduced from 93.14% to 71.69% after 15 days, the content of cellulose reduced from 34.12g·kg-1 to 25.66g·kg-1, the rate of degradation was 24.79% which was 10.60% higher than those without the strain. An anaerobic fermentation experiment was carried out with the two groups of composted corn straw and mixed pig feces with a certain ratio, and investigations of biogas production, pH, content of volatile fatty acids(VFA) and rate of methane production were conducted. The results were that the corn straw composted with the cellulose-degrading strain peaked 4 days earlier, the maximal daily biogas production was 1470mL, the cumulative biogas production reached 23641mL which was 16.87% higher and operated stably earlier. The study showed that the cellulose-degrading strain had a strong capacity to degrade cellulose in corn straw, and then improved the performance of anaerobic digestion.

Study of Methane Production by High Temperature Anaerobic Fermentation of Chicken Manure and Stalks

2020 ◽  
Vol 14 (4) ◽  
pp. 551-557
Author(s):  
Yongku Li ◽  
Xiaomin Hu ◽  
Lei Feng
Keyword(s):  
High Temperature ◽  
Anaerobic Digestion ◽  
Production Rate ◽  
Methane Production ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Gas Production ◽  
Chicken Manure ◽  
Biogas Slurry ◽  
Production Rates

The changing parameters, as the biogas production rate, the methane production rate, the cumulative biogas amount, the cumulative methane amount, the biogas composition, pH etc. in high temperature anaerobic fermentation of chicken manure and stalks were analyzed by experiments with different mass ratios of chicken manure or livestock manure and stalks with a high C/N ratio. The methane production mechanism of high temperature anaerobic digestion of chicken manure and stalks was discussed in detail. It showed that not only the biogas production rates but also the methane production rates of R1–R7 demonstrated the trend of initial increase and then decrease after 50 d of high temperature anaerobic digestion. Besides, the gas production of R1 with pure chicken manure stopped on the 30th d of the reaction. The gas production of other groups R2–R7 also stopped on the corresponding 34th, 36th, 36th, 37th, 37th, and 37th day, respectively. At the end of the reaction, the cumulative biogas amounts and the cumulative methane amounts of R1–R7 were 411.58 and 269.54, 459.91 and 314.41, 425.32 and 294.11, 401.85 and 272.54, 382.63 and 257.07, 363.04 and 218.16, and 257.15 and 160.10 N ml/(g VS). The biogas slurry pH of R1–R7 all demonstrated a trend of initial decrease and then increase, e. g., pH of R2 reached the minimum of 5.94 on the 5th day. pH values of other groups were between 6.01 and 6.39. After the addition of 4 g of sodium bicarbonate on the 7th day, biogas slurry pH of R1–R7 all increased. pH was maintained between 7.16 and 7.44 until the end of the reaction.

Sludge electrooxidation as pre-treatment for anaerobic digestion

2016 ◽  
Vol 75 (4) ◽  
pp. 775-781 ◽  
Author(s):  
J. A. Barrios ◽  
U. Duran ◽  
A. Cano ◽  
M. Cisneros-Ortiz ◽  
S. Hernández
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Wastewater Sludge ◽  
Boron Doped Diamond ◽  
Boron Doped ◽  
Treatment Conditions ◽  
Volatile Solids ◽  
Pre Treatment

Anaerobic digestion of wastewater sludge is the preferred method for sludge treatment as it produces energy in the form of biogas as well as a stabilised product that may be land applied. Different pre-treatments have been proposed to solubilise organic matter and increase biogas production. Sludge electrooxidation with boron-doped diamond electrodes was used as pre-treatment for waste activated sludge (WAS) and its effect on physicochemical properties and biomethane potential (BMP) was evaluated. WAS with 2 and 3% total solids (TS) achieved 2.1 and 2.8% solubilisation, respectively, with higher solids requiring more energy. After pre-treatment, biodegradable chemical oxygen demand values were close to the maximum theoretical BMP, which makes sludge suitable for energy production. Anaerobic digestion reduced volatile solids (VS) by more than 30% in pre-treated sludge with a food to microorganism ratio of 0.15 g VSfed g−1 VSbiomass. Volatile fatty acids were lower than those for sludge without pre-treatment. Best pre-treatment conditions were 3% TS and 28.6 mA cm−2.

Ultrasound pre-treatment for anaerobic digestion improvement

2009 ◽  
Vol 60 (6) ◽  
pp. 1525-1532 ◽  
Author(s):  
S. Pérez-Elvira ◽  
M. Fdz-Polanco ◽  
F. I. Plaza ◽  
G. Garralón ◽  
F. Fdz-Polanco
Keyword(s):  
Anaerobic Digestion ◽  
Energy Balance ◽  
Specific Energy ◽  
Biogas Production ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Net Generation ◽  
Batch Reactors ◽  
Anaerobic Reactors ◽  
Pre Treatment

Prior research indicates that ultrasounds can be used in batch reactors as pre-treatment before anaerobic digestion, but the specific energy required at laboratory-scale is too high. This work evaluates both the continuous ultrasound device performance (efficiency and solubilisation) and the operation of anaerobic digesters continuously fed with sonicated sludge, and presents energy balance considerations. The results of sludge solubilisation after the sonication treatment indicate that, applying identical specific energy, it is better to increase the power than the residence time. Working with secondary sludge, batch biodegradability tests show that by applying 30 kWh/m3 of sludge, it is possible to increase biogas production by 42%. Data from continuous pilot-scale anaerobic reactors (V=100 L) indicate that operating with a conventional HRT = 20 d, a reactor fed with pre-treated sludge increases the volatile solids removal and the biogas production by 25 and 37% respectively. Operating with HRT = 15 d, the removal efficiency is similar to the obtained with a reactor fed with non-hydrolysed sludge at HTR = 20 d, although the specific biogas productivity per volume of reactor is higher for the pretreated sludge. Regarding the energy balance, although for laboratory-scale devices it is negative, full-scale suppliers state a net generation of 3–10 kW per kW of energy used.

scholarly journals Evaluation of acidogenic sludge from anaerobic reactors running at low solids retention times to reduce sludge generation and enhance biogas production

Water SA ◽  
2019 ◽  
Vol 45 (4 October) ◽  
Author(s):  
Wilza Da Silva Lopes ◽  
Ysa Helena Diniz Morais de Luna ◽  
Jose Tavares de Sousa ◽  
Wilton Silva Lopes ◽  
Valderi Duarte Leite
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Kinetic Constant ◽  
Oxygen Demand ◽  
Gas Production ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Solids Retention ◽  
Improved Performance ◽  
Pre Treatment

ABSTRACT   Sludges generated in the biological processing of sewage are complex mixtures, the constituents of which pose risks to public health and the environment. Anaerobic digestion is considered the most sustainable option for treating sludge because it offers the possibility of generating biogas. The aim of this study was to compare the quantities, properties, biodegradabilities and biochemical methane potentials (BMP) of primary sludge (PS) generated by a primary decanter with acidogenic sludges produced by upflow anaerobic (UA) reactors operating at solids retention times (SRTs) of 2, 4, 6 and 8 days (Samples S2, S4, S6 and S8, respectively). Sludges from both pre-treatments were submitted to alkaline solubilization in order to determine the efficiency of the process in disrupting extracellular complexes. Based on the levels of total solids (TS) present, the primary decanter was found to generate higher quantities of excess sludge (yield of 3.1 gTS∙d-1) than UA reactors operating at low SRTs (yields in the range 1.69 to 0.64 gTS∙d-1). The concentrations of dissolved materials in PS and Samples S2 and S8 were considerably higher after alkaline solubilization, with respective increases of 8, 14 and 28-fold in dissolved organic carbon, 12, 20 and 40-fold in chemical oxygen demand, 25, 31 and 59-fold in proteins, and 17, 21 and 63-fold in carbohydrates. In addition, the BMP value for S8 was some 13% higher than that recorded for PS while the kinetic constant for gas production by S8 was 1.8-fold greater than that of PS. It is concluded that a pre-treatment combining anaerobic digestion at low SRT and alkaline solubilisation would lead to improved performance in subsequent stages of anaerobic digestion and, consequently, increased efficiency in biogas production.

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