scholarly journals Volatile Fatty Acids Production from Microalgae Biomass: Anaerobic Digester Performance and Population Dynamics during Stable Conditions, Starvation, and Process Recovery

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4544 ◽  
Author(s):  
Jose Antonio Magdalena ◽  
Elia Tomás-Pejó ◽  
Cristina González-Fernández
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Starvation Period ◽  
Reactor Performance ◽  
Methane Generation ◽  
Microbial Response ◽  
Stable Conditions ◽  
Microbial Analysis ◽  
Process Disturbances ◽  
The Impact

Disturbances in anaerobic digestion (AD) negatively impact the overall reactor performance. These adverse effects have been widely investigated for methane generation. However, AD recently appeared as a potential technology to obtain volatile fatty acids (VFAs) and thus, the impact of process disturbances must be evaluated. In this sense, microbial response towards a starvation period of two weeks was investigated resulting in a conversion of organic matter into VFAs of 0.39 ± 0.03 COD-VFAs/CODin. However, the lack of feeding reduced the yield to 0.30 ± 0.02 COD-VFAs/CODin. Microbial analysis revealed that the starvation period favored the syntrophic acetate-oxidizing bacteria coupled with hydrogenotrophic methanogens. Finally, the system was fed at 9 g COD/Ld resulting in process recovery (0.39 ± 0.04 COD-VFAs/CODin). The different microbiome obtained at the end of the process was proved to be functionally redundant, highlighting the AD robustness for VFAs production.

Hybrid reactor performance in pentachlorophenol (pcp) removal by anaerobic granules

2001 ◽  
Vol 44 (4) ◽  
pp. 137-144 ◽  
Author(s):  
M. De Almeida Prado Montenegro ◽  
E. De Mattos Moraes ◽  
H. Moreira Soares ◽  
R. Filomena Vazoller
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Culture Media ◽  
Biogas Production ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Concentration Addition ◽  
Hybrid Reactor ◽  
Reactor Performance

The present research aimed at evaluating pentachlorophenol (PCP) degradation in a hybrid reactor supplied with a mixture of fatty acids (propionic, butyric, acetic and lactic) and methanol. The performance of the reactor is remarkably stable and efficient during PCP additions at range of 2.0 to 21.0 mg/L. The reduction of chemical oxygen demand (COD) was around 97% and methane was found to be 86% in the biogas production. The efficiency of volatile fatty acids breakdown was 93%, 64% and 74% respectively for butyric, propionic and acetic. PCP total removal of more than 99% was reached by granular sludge activities formed during 21 months of reactor operation. Methanogenic microorganisms predominance was noticed with 105 to 106 cells/mL during enumeration on methanol or lactate added to sulfate culture media. The removal rate was 1.07 mg PCP · g−1 VS · d−1 during the highest PCP concentration addition.

Toxicity of pH, Ammonia and Volatile Fatty Acids on Hydrogenotrophic Methanogen-Enriched Sludge

2014 ◽  
Vol 955-959 ◽  
pp. 527-531
Author(s):  
Jian Zheng Li ◽  
Yu Peng Zhang ◽  
Chong Liu ◽  
Ze Yu Tang
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Anaerobic Digestion ◽  
Propionic Acid ◽  
Butyric Acid ◽  
Volatile Fatty Acids ◽  
Batch Experiments ◽  
Inhibitory Effects ◽  
Hydrogenotrophic Methanogen ◽  
The Impact

The activities of methanogen are easily affected by inhibitory substances and lead to anaerobic digestion failure. To investigate inhibitory effects on methanogenesis of a methanogen-enriched sludge, pH, volatile fatty acids (such as acetic acid, propionic acid and butyric acid), and ammonia were used as inhibitory factors and a L16(45) orthogonal table was employed to design batch experiments. The result of variance analyses shows that pH has the greatest impact on the methanogenesis of the enriched culture. The impact of butyrate, NH3, acetate and propionate was decreased in order. DGGE finger-print shows that there was only one methanogen in the inoculum sludge.

scholarly journals Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

2015 ◽  
Vol 12 (21) ◽  
pp. 6503-6514 ◽  
Author(s):  
C. Arslan ◽  
A. Sattar ◽  
C. Ji ◽  
S. Sattar ◽  
K. Yousaf ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Hydrogen Production ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Negative Impact ◽  
Glucose Consumption ◽  
Statistical Modelling ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
The Impact

Abstract. The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste. The maximum cumulative bio-hydrogen production of 650 mL was obtained from noodle waste under thermophilic temperature condition. Most of the production was observed during the first 48 h of incubation, which continued until 72 h of incubation. The decline in pH during this interval was 4.3 and 4.4 from a starting value of 7 under mesophilic and thermophilic conditions, respectively. Most of the glucose consumption was also observed during 72 h of incubation and the maximum consumption was observed during the first 24 h, which was the same duration where the maximum pH drop occurred. The maximum hydrogen yields of 82.47 mL VS−1, 131.38 mL COD−1, and 44.90 mL glucose−1 were obtained from thermophilic food waste, thermophilic noodle waste and mesophilic rice waste, respectively. The production of volatile fatty acids increased with an increase in time and temperature in food waste and noodle waste reactors whereas they decreased with temperature in rice waste reactors. The statistical modelling returned good results with high values of coefficient of determination (R2) for each waste type and 3-D response surface plots developed by using models developed. These plots developed a better understanding regarding the impact of temperature and incubation time on bio-hydrogen production trend, glucose consumption during incubation and volatile fatty acids production.

Impact of volatile fatty acids to alkalinity ratio and volatile solids on biogas production under thermophilic conditions

2020 ◽  
pp. 0734242X2095739
Author(s):  
Abdul-Aziz Issah ◽  
Telesphore Kabera
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Total Alkalinity ◽  
Stable Range ◽  
Start Up ◽  
Volatile Solids ◽  
Significant Difference ◽  
Thermophilic Conditions ◽  
The Impact

The study assessed the impact of volatile fatty acids (VFA) to total alkalinity (TA) ratio (VFA/TA), and percentage volatile solids (VS) reduction of batch and semi-continuous anaerobic co-digestion of palm nut paste waste (PNPW) and anaerobic-digested rumen waste (ADRW) on digester stability and biogas production under the environmental condition of 50 ± 1°C and hydraulic retention time of 21 days for the batch studies and 14 days for semi-continuous co-digestion. The co-digestion ratios were based on percentage digester volume corresponding to 90%:10%, 75%:25% and 50%:50%. During batch and semi-continuous anaerobic co-digestion, VFA/TA of 0.32–1.0 and VS reduction of 53–67% were observed as the stable range at which biogas production was maximum. In terms of semi-continuous anaerobic digestion (AD), except for the 50%:50% ratio where biogas production progressed steadily from the first to fourteenth days, biogas production initially dropped from 180.1 to 171.3 mL between the first and third days of the 90%:10% reaching a maximum of 184 mL on the fourteenth day. Biogas production declined from 198.8 to 187.5 mL on the second day and then increased to 198.8 ± 0.5 mL in the case of the 75%:25% with a significant difference between the treatment ratios at p < 0.05. Therefore, the study can confirm that the 50%:50% ratio (PNPW:ADRW) is a suitable option for managing crude fat-based waste under thermophilic AD due to its potential for rapid start-up and complete biodegradation of active biomass within a 21-day period. This presupposes that residual methane as greenhouse gas will be void in the effluent if disposed of.

Effects of solids concentration, pH and carbon addition on the production rate and composition of volatile fatty acids in prefermenters using primary sewage sludge

2006 ◽  
Vol 53 (8) ◽  
pp. 263-269 ◽  
Author(s):  
R.J. Zeng ◽  
Z. Yuan ◽  
J. Keller
Keyword(s):  
Fatty Acids ◽  
Production Rate ◽  
Propionic Acid ◽  
Volatile Fatty Acids ◽  
Productivity Loss ◽  
Domestic Wastewater ◽  
Biological Phosphorus Removal ◽  
Operational Conditions ◽  
Solids Concentration ◽  
The Impact

Increasing evidence is emerging that the performance of enhanced biological phosphorus removal (EBPR) systems relies on not only the total amount but also the composition of volatile fatty acids (VFAs). Domestic wastewater often contains limited amounts of VFAs with acetic acid typically being the dominating species. Consequently, prefermenters are often employed to generate additional VFAs to meet the demand for carbon by EBPR and/or denitrification processes. Limited knowledge is currently available on the effects of operational conditions on the production rate and composition of VFAs in prefermenters. In this study, a series of controlled batch experiments were conducted with sludge from a full-scale prefermenter to determine the impact of solids concentration, pH and addition of molasses on prefermentation processes. It was found that an increase in solids concentration enhanced total VFA production with an increased propionic acid fraction. The optimal pH for prefermentation was in the range of 6–7 with significant productivity loss when pH was below 5.5. Molasses addition significantly increased the production of VFAs particularly the propionic acid. However, the fermentation rate was likely limited by the biological activity of the sludge rather than by the amount of molasses added.

scholarly journals Enhancement of Anaerobic Digestion of Waste-Activated Sludge by Conductive Materials under High Volatile Fatty Acids-to-Alkalinity Ratios

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 391
Author(s):  
Paolo S. Calabrò ◽  
Filippo Fazzino ◽  
Carlo Limonti ◽  
Alessio Siciliano
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Municipal Wastewater ◽  
Steel Scrap ◽  
Waste Activated Sludge ◽  
Municipal Wastewater Treatment ◽  
Conductive Materials ◽  
Stable Conditions

Anaerobic digestion (AD) represents a suitable option for the management of the waste-activated sludge (WAS) produced in municipal wastewater treatment plants. Nevertheless, due to its complex characteristics, WAS is often barely degradable under conventional anaerobic processes. The use of conductive materials during AD provides a promising route for enhancing WAS digestion, through the effects of direct inter-species electron transfer (DIET). The present paper aims to evaluate the effects of the addition of four different materials—granular activated carbon (GAC), granular iron, and aluminium and steel scrap powders—in semi-continuous lab-scale reactors under very high volatile fatty acids-to-alkalinity ratios. In particular, the use of metallic aluminium in WAS digestion was investigated for the first time and compared to the other materials. The AD of WAS without the addition of conductive materials was impossible, while the use of steel powder and zero-valent iron is shown not to improve the digestion process in a satisfactory way. On the contrary, both GAC and Al allow for effective WAS degradation. At stable conditions, methane yields of about 230 NmLCH4/gVS and 212 NmLCH4/gVS are recorded for GAC- and Al-amended reactors, respectively. These two materials are the most promising in sustaining WAS AD through DIET also in case of unbalanced volatile fatty acids-to-alkalinity ratios.

Impact of variation in yield of gas during incubation on simulated gas production and extent of ruminal degradation

1999 ◽  
Vol 1999 ◽  
pp. 38-38
Author(s):  
J. Dijkstra ◽  
J. France ◽  
S. Lopez ◽  
M.S. Dhanoa
Keyword(s):  
Fatty Acids ◽  
Simulation Study ◽  
Degradation Rate ◽  
Volatile Fatty Acids ◽  
Soluble Sugars ◽  
Gas Production ◽  
Production Technique ◽  
Substrate Degradation ◽  
Ruminal Degradation ◽  
The Impact

To calculate the extent of ruminal degradation based on the gas production technique, equations were derived to describe gas production profiles from substrate degradation (France et al. submitted). This derivation demonstrated that if the yield of gas (Y; ml/g degradable OM) produced during the course of incubation varies significantly, then the calculated extent of degradation is not correct. Variation in Y may occur due to variation in the yield of individual volatile fatty acids (VFA) produced. The objective of this simulation study was to examine the impact of variation in individual VFA production and consequently in yield of gas on the extent of ruminal degradation.Gas production profiles were simulated based on a generalized Mitscherlich (GM) equation (see France et al. submitted) for three substrates (soluble sugars, starch, fibre) that differ in degradation rate and VFA production profile (see Table 1).

scholarly journals The impact of starter culture on the pH and the content of lactic and volatile fatty acids in boiled-smoked sausages

2015 ◽  
Vol 56 (1) ◽  
pp. 34-40
Author(s):  
Dijana Indzhelieva ◽  
Katja-Jorgova Valkova ◽  
Aco Kuzelov ◽  
Darko Andronikov
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Starter Culture ◽  
The Impact
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