Extremely fast increase in the organic loading rate during the co-digestion of rapeseed oil and sewage sludge in a CSTR – characterization of granules formed due to CaO addition to maintain process stability

2015 ◽  
Vol 72 (9) ◽  
pp. 1569-1577 ◽  
Author(s):  
M. Kasina ◽  
A. Kleyböcker ◽  
M. Michalik ◽  
H. Würdemann
Keyword(s):  
Fatty Acids ◽  
Sewage Sludge ◽  
Rapeseed Oil ◽  
Loading Rate ◽  
Organic Loading Rate ◽  
Long Chain Fatty Acids ◽  
Organic Loading ◽  
Granule Formation ◽  
Fast Increase ◽  
Long Chain

In a co-digestion system running with rapeseed oil and sewage sludge, an extremely fast increase in the organic loading rate was studied to develop a procedure to allow for flexible and demand-driven energy production. The over-acidification of the digestate was successfully prevented by calcium oxide dosage, which resulted in granule formation. Mineralogical analyses revealed that the granules were composed of insoluble salts of long chain fatty acids and calcium and had a porous structure. Long chain fatty acids and calcium formed the outer cover of granules and offered interfaces on the inside thereby enhancing the growth of biofilms. With granule size and age, the pore size increased and indicated degradation of granular interfaces. A stable biogas production up to the organic loading rate of 10.4 kg volatile solids m−3 d−1 was achieved although the hydrogen concentration was not favorable for propionic acid degradation. However, at higher organic loading rates, unbalanced granule formation and degradation were observed. Obviously, the adaption time for biofilm growth was too short to maintain the balance, thereby resulting in a low methane yield.

Influence of mesophilic and thermophilic conditions on the anaerobic digestion of food waste: Focus on the microbial activity and removal of long chain fatty acids

2018 ◽  
Vol 36 (11) ◽  
pp. 1106-1112 ◽  
Author(s):  
Xiaohui Guo ◽  
Kang Kang ◽  
Gaoyuan Shang ◽  
Xiunan Yu ◽  
Ling Qiu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Microbial Activity ◽  
Food Waste ◽  
Biogas Production ◽  
Organic Loading Rate ◽  
Long Chain Fatty Acids ◽  
Methanogenic Activity ◽  
Long Chain ◽  
Chain Fatty Acids

The mesophilic reactor (MR) exhibited advantages in biogas production and performance stability over thermophilic reactor (TR) during the long-term anaerobic digestion (AD) of food waste (FW) with stepwise organic loading rate elevating. It was interesting to explore the mechanism causing the divergences in performances between these two reactors. The microbial activity was compared on day 110 when TR began to deteriorate. The results show that MR had significantly higher specific acetoclastic methanogenic activities (SAMA) and specific propionate and butyrate oxidative activities (SPOA and SBOA) than TR. The SAMA, SPOA and SBOA in TR were only 50.3%, 18.6% and 46.4% of those values in MR, respectively. Remarkably, the specific hydrogenotrophic methanogenic activity of 15.5±2.1, 15.7±4.6 mmol CH4·L−1 original slurry·d−1 in MR and TR was comparative with insignificant difference, which indicates that the microbial activity in TR had been inhibited widely apart from the hydrogenotrophic methanogenesis. Additionally, many particles with the diameters of 1–2 mm were observed to form in MR and identified as complexes of calcium and long chain fatty acids (LCFAs). The formation of calcium crystallization might alleviate the inhibition of LCFAs during AD of FW, which further supports the better performance in MR than TR.

Volatile fatty acids production from food waste: Effects of pH, temperature, and organic loading rate

2013 ◽  
Vol 143 ◽  
pp. 525-530 ◽  
Author(s):  
Jianguo Jiang ◽  
Yujing Zhang ◽  
Kaimin Li ◽  
Quan Wang ◽  
Changxiu Gong ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Effects Of Ph

scholarly journals Experiments and Modeling for Flexible Biogas Production by Co-Digestion of Food Waste and Sewage Sludge

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 818 ◽  
Author(s):  
Yiyun Liu ◽  
Tao Huang ◽  
Xiaofeng Li ◽  
Jingjing Huang ◽  
Daoping Peng ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Food Waste ◽  
Loading Rate ◽  
Biogas Production ◽  
Operating Conditions ◽  
Utilization Efficiency ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Feeding Mode ◽  
Rapid Responses

This paper explores the feasibility of flexible biogas production by co-digestion of food waste and sewage sludge based on experiments and mathematical modeling. First, laboratory-scale experiments were carried out in variable operating conditions in terms of organic loading rate and feeding frequency to the digester. It is demonstrated that biogas production can achieve rapid responses to arbitrary feedings through co-digestion, and the stability of the anaerobic digestion process is not affected by the overloading of substrates. Compared with the conventional continuous mode, the required biogas storage capacity in flexible feeding mode can be significantly reduced. The optimum employed feeding organic loading rate (OLR) is identified, and how to adjust the feeding scheme for flexible biogas production is also discussed. Finally, a simplified prediction model for flexible biogas production is proposed and verified by experimental data, which could be conveniently used for demand-oriented control. It is expected that this research could give some theoretical basis for the enhancement of biogas utilization efficiency, thus expanding the applications of bio-energy.

Volatile Fatty Acids Production by Anaerobic Whey Permeate Biodegradation in a Continuous Bioreactor

1998 ◽  
Vol 33 (4) ◽  
pp. 551-564 ◽  
Author(s):  
Nathalie Imbeault ◽  
Marcel Paquet ◽  
Raynald Côté
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Transformation Efficiency ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Hydraulic Residence Time ◽  
Whey Permeate ◽  
Continuous Bioreactor ◽  
Initial Load

Abstract This paper addresses the production of volatile fatty acids with fermentation of whey permeate under acidogenic conditions. The coal-immobilized biomass of an anaerobic fluidized bed reactor operated with a fairly constant hydraulic residence time of 12 min transformed the substrate (whey permeate i.e., essentially lactose) into a blend of acetic, propionic, butyric and isobutyric acids corresponding to between 2 and 19, 1 and 6, 11 and 30, 0 and 2% of the initial load (carbon basis), respectively. There was a slight decrease in the sugar transformation efficiency (65 to 48%) with the increase of the organic loading rate (OLR) which varied from 586 to 3339 g sugar/Lreactord. At the highest OLR of 3339 g sugar/Lreactor.d, the biomass transformed 19% of the substrate into a blend of acetic, propionic, butyric and isobutyric acids. Residual sugar and bio-gas were 52 and 2%, respectively, of the initial load (carbon basis). Cet article fait référence L une étude sur la production d’acides gras volatiles par fermentation anaérobie du perméat de lactosérum dans un bioréacteur. La biomasse fixée aux grains de charbon composant le lit fluidisé, opérant avec un temps de rétention hydraulique de 12 minutes, transformait le substrat (perméat i.e., essentiellement lactose) en un mélange d’acide acétique, propionique, n-butyrique et isobutyrique correspondant respectivement L 2 et 19, 1 et 6, 11 et 30, 0 et 2% de la charge initiale (sur la base d’un bilan de carbone). Il a été possible d’observer une légère diminution de l’efficacité de la biodégradation du sucre (65 L 48%) avec une augmentation du taux de charge organique lequel variait de 586 L 3 339 g de sucre/Lréacteurd. L la charge organique la plus forte, soit 3 339 g de sucre/Lréacteur.d, la biomasse transformait le substrat L 19% en un mélange d’acide acétique, propionique, n-butyrique et isobutyrique. La part du sucre résiduel était de 52% et celle du biogaz L 2% (bilan de carbone).

Start-Up Performances of High-Solid Anaerobic Digestion of Sewage Sludge under Mesophilic Condition

2011 ◽  
Vol 356-360 ◽  
pp. 2020-2026 ◽  
Author(s):  
Ni Na Duan ◽  
Bin Dong ◽  
Qun Biao He ◽  
Xiao Hu Dai
Keyword(s):  
Sewage Sludge ◽  
Loading Rate ◽  
Sharp Decrease ◽  
Total Solid ◽  
Methane Yield ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
High Solid ◽  
Stirred Tank Reactors ◽  
Start Up

High-solid anaerobic digestions of sewage sludge were investigated in completely stirred tank reactors (CSTR) at 35±1°C. The total solid (TS) concentrations of the sludge fed to the reactors were designed at 10%, 15% and 20% respectively after start-up periods. By start-up period is meant the TS concentration of the substrate in the reactor has not reached its designed level. Special attention was paid to the effect of organic loading rate (OLR), TS concentration, and ammonia inhibition on methane yield, volatile solid (VS) reduction and volatile fatty acid (VFA) concentration during the start-up periods. Experimental results showed that no evident inhibition of TS or ammonia was found as long as the concentration of TS was below 10% or the concentration of ammonia-N was below 2000 mg/l. Digestion at TS concentration of 12.5%-14.8% was slightly influenced by ammonia at concentration of 3200-3800 mg N/l. As the TS concentration was above 14.8%, the ammonia-N concentration of 3500-3800 mg/l showed evident inhibition on methanogetic activity, leading to sharp decrease of methane yield and methane content. After start-up, the methane yields at feeding TS of 10%, 15%, and 20% at OLR of 3.0 kg VS m-3d-3 were 0.221, 0.248 and 0.177 l CH4 g-1VSadded-1 d-1, and the VS reduction were 33%, 39.5% and 40%, respectively.

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