scholarly journals Substrate-induced pH changes and process stability of anaerobic digestion of shea waste

2021 ◽  
Vol 24 (12) ◽  
pp. 2035-2042
Author(s):  
Martin Ampadu Ofosu ◽  
Melvin-Guy Adonadaga ◽  
Isaac Sackey ◽  
Boateng Ampadu
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Environmental Concern ◽  
Biogas Production ◽  
Cattle Manure ◽  
Shea Butter ◽  
Cattle Dung ◽  
Process Stability ◽  
Alternative Source ◽  
Ph Changes

Shea butter extraction involves the generation of waste of environmental concern. To help find a solution to the management of this waste, and to search for an alternative source of energy, this study was carried out to investigate the potential of shea waste in generating methane gas through anaerobic digestion. At high concentrations, volatile fatty acids produce a low pH, which may inhibit hydrolysis, thereby affecting the stability of the anaerobic digestion process. The influence of pH changes on process stability (or otherwise) was also investigated. The study involved two fermentation processes: mono-fermentation and co-fermentation involving a mix of shea waste and cattle dung. The mono-fermentation investigations comprised six treatments - three organic dry matter concentrations of 7%, 5% and 3%, combined with two hydraulic retention times of 30 and 60 days. The co-fermentation investigations comprised three treatments of shea waste and cattle manure mix in proportions (by volume) of 50:50, 75:25 and 90:10. The results showed that changes in pH were a good parameter for indicating process instability. The results also showed that monofermentation of shea waste was not a viable option in anaerobic digestion for biogas production, whilst only the substrate with 50% cattle manure in the co-fermentation trials showed process stability, producing biogas with adequate methane content.

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.

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.

scholarly journals Effect of liquid digestate recirculation on biogas production and enzyme activities for anaerobic digestion of corn straw

2020 ◽  
Author(s):  
Shuaixing Xue ◽  
Ling Qiu ◽  
Xiaohui Guo ◽  
Yiqing Yao
Keyword(s):  
Anaerobic Digestion ◽  
Enzyme Activities ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Coenzyme F420 ◽  
Total Volatile ◽  
Corn Straw ◽  
Liquid Digestate ◽  
Acid Accumulation ◽  
Peak Value

Abstract To accelerate the degradation of substrate, 50% liquid digestate recirculation (LDR) was used in the anaerobic digestion (AD) of corn straw. The effects of recirculation on the enzyme activities and biogas production were investigated by comparing with control reactor (ReactorCK). During the AD process, the fermentation system with 50% LDR was more stable. The average biogas and methane production in ReactorLDR were 7,891 mL·d−1 and 347 mL CH4·g−1 VSadded·d−1 respectively. The total volatile fatty acids (TVFAs) concentration in the two reactors both increased at first and then decreased with time. The LDR made the VFAs accumulation significant, especially propionic acid accumulation in 4 ∼ 16 days. The maximum peak value of cellulase, xylanase, dehydrogenase and coenzyme F420 activities in ReactorLDR were 0.51 mg·g−1·h−1, 0.29 mg·g−1·h−1, 4.88 mL·g−1·h−1 and 6.69 μmol·L−1, respectively, which were higher than that in ReactorCK. With or without recirculation, the concentration of TVFAs was positively correlated with cellulase, xylanase and dehydrogenase activities, while was negatively correlated with coenzyme F420 activity. Besides, a very significant correlation existed between hydrolase and dehydrogenase activities and daily biogas production in ReactorCK. And the peaks of cellulase, xylanase and dehydrogenase activities appeared ahead of the peak of daily biogas production with the LDR.

Study on the biogas potential of anaerobic digestion of coffee husks wastes in Ethiopia

2020 ◽  
pp. 0734242X2093961 ◽  
Author(s):  
Ning Du ◽  
Meng Li ◽  
Qian Zhang ◽  
Mihret Dananto Ulsido ◽  
Ruyi Xu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Organic Matter ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Dual Purpose ◽  
Effective Utilization ◽  
Leading Role ◽  
Initial Ph ◽  
Waste Reclamation

The poorly controlled discharge of coffee husks in Ethiopia causes severe environmental pollution and is a waste of resources. The volatile solid and carbon content in coffee husks waste indicates that it is rich in organic matter and has huge potential to produce biogas. This study investigated the feasibility of coffee husks to produce biomass through anaerobic digestion, based on temperature, initial pH, inoculum/substrate (I/S) ratio and carbon/nitrogen (C/N) ratio. The study demonstrated that the maximum production of biogas and methane reached 3359.6 ml and 2127.30 ml, respectively, under the conditions of mesophilic temperature (35±1°C), an initial pH of 7, an I/S ratio of 0.75 and a C/N ratio of 30. Based on this result, the effects of trace elements (Fe2+, Ni2+, Co2+) on biogas production and methane content were also explored. Compared with the group with no addition of trace elements, the experiment adding trace elements had significant enhancement effects on the production of biogas and methane, in which Fe2+ played a leading role ( p<0.05). Fe2+ promoted the hydrolysis and acidification of coffee husks, resulting in the production of a series of intermediates such as volatile fatty acids and the other kinds of dissolved organic matter. Furthermore, the cooperation of Ni2+, Co2+ and Fe2+ enhanced the activity of the enzyme system in methanogens, promoting methane production. The results in this paper show that coffee husks have clear biogas potential through anaerobic digestion, and its effective utilization could fulfill the dual purpose of solid waste reclamation and local environmental protection in Ethiopia.

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.

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.

Statistical modelling of the impact of some polyphenols on the efficiency of anaerobic digestion and the co-digestion of the wine distillery wastewater with dairy cattle manure and cheese whey

2010 ◽  
Vol 62 (3) ◽  
pp. 475-483 ◽  
Author(s):  
M. Akassou ◽  
A. Kaanane ◽  
A. Crolla ◽  
C. Kinsley
Keyword(s):  
Anaerobic Digestion ◽  
Dairy Cattle ◽  
Biogas Production ◽  
Degradation Kinetics ◽  
Inhibitory Effect ◽  
Cattle Manure ◽  
Coumaric Acid ◽  
Biogas Yield ◽  
Distillery Wastewater ◽  
The Impact

The objective of this study was to determine the effectiveness of anaerobic digestion in the treatment of polyphenols (PP) present in olive mill wastewater (OMW) and wine distillery wastewater (WDW). Anaerobic Toxicity Assay (ATA) was conducted to assess the impact of the most representative phenolic compounds present in OMW and WDW: catechol, tannins and p-Coumaric acid, on biogas production. The results from this study show that tannins do not present any inhibitory effect on methanogenesis at a concentration level of 1,664 ppm, whereas catechol has an inhibitory effect at 1,664 ppm. In addition, p-Coumaric acid was strongly inhibitory at 50 ppm. The co-digestion of OMW and WDW with other effluents was proposed as a solution for reducing the load of PP in the anaerobic medium. Biochemical methane potential (BMP) tests were carried out for dairy cattle manure and mixtures of five PP. A central composite design was implemented on the BMP tests to model the biogas production response and the degradation kinetics of PP. The co-digestion of WDW with cattle manure and/or whey was also investigated in BMP tests. The results show that the digestion was optimal at a ratio of 16: 64: 20 (WDW: manure: inoculum) with a maximum biogas yield of 172 mL/g of VS and 66% COD removal.

scholarly journals Limiting factors for anaerobic digestion of olive mill wastewater blends under mesophilic and thermophilic conditions

2018 ◽  
Vol 49 (2) ◽  
pp. 130-137
Author(s):  
Demetrio Antonio Zema ◽  
Giovanni Zappia ◽  
Souraya Benalia ◽  
Giuseppe Zimbalatti ◽  
Enzo Perri ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Olive Mill Wastewater ◽  
Limiting Factors ◽  
Citrus Peel ◽  
Thermophilic Conditions ◽  
High Concentrations ◽  
Olive Mill

Experimental trials of anaerobic digestion of olive mill wastewater (OMW) blended with other agro-industrial by-products were carried out to evaluate biogas production and sensitivity of the process to inhibiting compounds. Blends containing different percentages of OMW, digested liquid manure, and citrus peel were subjected to a batch anaerobic digestion process under both mesophilic and thermophilic conditions. The results showed that blends with percentages of OMW higher than 20% (v/v) had low methane yields due high concentrations of polyphenols (PPs) and/or volatile fatty acids (concentrations above 0.8 g kg–1 and 2.4 g L–1, respectively). The addition of other substrates such as citrus peel may have induced synergic inhibiting effects of PPs and essential oils (EO) on microbial growth. Thermophilic processes were more sensitive to these inhibiting compounds than mesophilic processes. The results of this study suggest that reducing PPs and EO concentrations in blends subject to anaerobic digestion below the inhibiting concentrations of 0.6 g L–1 and 0.5 g kg–1, respectively, is suitable. Additionally, it is advisable to maintain the volatile fatty acids content below 2 g L–1 to avoid its evident toxic effects on the growth of microorganisms in biochemical processes.

Sign in / Sign up

Export Citation Format

Share Document