Acidogenic fermentation of source separated mixtures of vegetables and fruits wasted from supermarkets (original) (raw)
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Effect of pH on types of acidogenic fermentation of fruit and vegetable wastes
Biotechnology and Bioprocess Engineering, 2015
The effect of pH (4.0, 5.0, and 6.0) on acidification and fermentation of fruit and vegetable wastes was investigated using batch and semi-continuous experiments under mesophilic condition. Results showed that fermentation types change with pH variation. The pH of acidification system containing fruit and vegetable wastes could automatically decrease to 3.0~4.0. At this pH range, a stable ethanol production was observed, at which ethanol-type fermentation was obtained. Based on the results, the fermentation types were classified into ethanol-type, mixed acid-type, propionic acid-type, and butyric acid-type fermentations, which occurred at pH 4.0~4.
Acidogenic Fermentation of the Organic Fraction of Municipal Solid Wastes
Chemistry for the Protection of the Environment, 1991
The problem of fossil fuels dependency is being addressed through sustainable bio-fuels and bio-products production worldwide. At the base of this bio-based economy there is the efficient use of biomass as nonvirgin feedstock. Through acidogenic fermentation, organic waste can be valorised in order to obtain several precursors to be used for bio-plastic production. Some investigations have been done but there is still a lack of knowledge that must be filled before moving to effective full scale plants. Acidogenic fermentation batch tests were performed using food waste (FW) and cheese whey (CW) as substrates. Effects of nine different combinations of substrate to inoculum (S/I) ratio (2, 4, and 6) and initial pH (5, 7, and 9) were investigated for metabolites (acetate, butyrate, propionate, valerate, lactate, and ethanol) productions. Results showed that the most abundant metabolites deriving from FW fermentation were butyrate and acetate, mainly influenced by the S/I ratio (acetate and butyrate maximum productions of 21.4 and 34.5 g/L, respectively, at S/I = 6). Instead, when dealing with CW, lactate was the dominant metabolite significantly correlated with pH (lactate maximum production of 15.7 g/L at pH = 9).
Environmental Science and Pollution Research
This study is focused on the effects of pH on the production of volatile fatty acids (VFAs) and their distribution through the acidogenic fermentation of source-sorted organic fraction of municipal solid waste (OFMSW) from a mechanical-biological treatment (MBT) plant, and food waste (FW) from a university canteen. In semi-continuous lab-scale digesters using OFMSW at a hydraulic retention time (HRT) of 3.5 days under acidic conditions (pH 6.0), the VFA concentration in the effluent increased to 9.8-11.5 g L −1 (VS content of the feedstock between 4.2 and 5.2% w/w), while its individual VFA profiling was similar to the influent which was already prefermented (namely, C 2 35-41%, C 3 18-22%, C 4 17-21%, and C 5 9-12%). When working with the same conditions but using FW as feedstock, an effluent with a VFA concentration up to 11.5 g VFA L −1 (FW with a VS content of 5.5% w/w) and a stable distribution of C 2 and C 4 acids (up to 60.3% and 12.9%, respectively) but with very low quantities of C 3 and C 5 acids (lower than 1.8 and 2.7%, respectively) was obtained. Anaerobic batch tests using FW revealed that alkaline pH near 9 could lead to higher VFA production with high acetic acid content when compared to pH 6. In the semi-continuous fermenters working at alkaline conditions (pH 9.5-10) using OFMSW and FW, an enhanced solubilization of organic matter was registered with respect to the fermenters working under acidic conditions. This fact was not reflected in a higher VFA production when using OFMSW as feedstock, probably due to free ammonia inhibition, since OFMSW was mixed in the MBT plant with supernatant from anaerobic digestion of this biowaste. However, when using FW, alkaline conditions lead to an enhanced VFA production with respect to the reactor working under acidic conditions, being acetic acid the predominant product, which represented up to 91% of the VFA spectrum obtained.
Bioreactor performance in anaerobic digestion of fruit and vegetable wastes
Process Biochemistry, 2005
This work reviews the potential of anaerobic digestion for material recovery and energy production from fruit and vegetable wastes (FVW). These wastes contain 8-18% total solids (TS), with a total volatile solids (VS) content of 86-92%. The organic fraction includes about 75% easy biodegradable matter (sugars and hemicellulose), 9% cellulose and 5% lignin. Anaerobic digestion of FVW was studied under different operating conditions using different types of bioreactors. It permits the conversion of 70-95% of organic matter to methane, with a volumetric organic loading rate (OLR) o f 1-6.8 g versatile solids (VS)/l day. A major limitation of anaerobic digestion of FVW is a rapid acidification of these wastes decreasing the pH in the reactor, and a larger volatile fatty acids production (VFA), which stress and inhibit the activity of methanogenic bacteria. Continuous two-phase systems appear as more highly efficient technologies for anaerobic digestion of FVW. Their greatest advantage lies in the buffering of the organic loading rate taking place in the first stage, allowing a more constant feeding rate of the methanogenic second stage. Using a two-stage system involving a thermophilic liquefaction reactor and a mesophilic anaerobic filter, over 95% volatile solids were converted to methane at a volumetric loading rate of 5.65 g VS/l d. The average methane production yield was about 420 l/kg added VS.
2018
The applicability of two laboratory-scale bioreactors for solid-state cultivation of white-rot fungus Trametes versicolor TV6 was investigated. Sugar beet pulp (SBP) was used as a noninert carrier. Two bioreactor configurations were investigated: horizontal bioreactor (HB) and tray bioreactor (TB). SBP biodegradation was observed in both investigated bioreactors, whereas the obtained material mass loss was 21.33% and 46.50% for HB and TB, respectively. The decrease of cellulose (64.65% HB and 42.34% TB) and pentosane content (42.39% HB and 62.61% TB), as well as the ash content increase (175.5% HB and 78.9% TB), indicated good biodegradation capability of the fungus. Furthermore, the results indicate that both bioreactors could be used for biological degradation/pre-treatment of lignocellulosic materials for different biotechnological purposes using white-rot fungus T. versicolor TV6.
Chemical engineering transactions, 2021
Biorefinery represents an innovative approach for waste management, where products at the end of their service life are seen as valuable resources for the production of high added value bio-products or bio-fuels. In this context, acidogenic fermentation is gaining scientific and commercial interest, since it allows to improve waste/wastewater treatability as well as additional recovery of volatile fatty acids (VFA), the building blocks for the chemical industry or precursors of reduced chemicals in conventional organic chemistry. This work illustrates the results of a study aimed at highlighting the effects of different inputs (feedstock composition and pre-treatment; temperature) on process performance and safety. The fermentation process was applied on a mixture of food waste and sewage sludge (FWs-SS) within the contest of Treviso municipality (northeast Italy). The VFA production and relative ratio respect to soluble chemical oxygen demand (CODSOL) were evaluated, as well as the...
2021
Acidogenic fermentation of wastes produces volatile fatty acid (VFA)-rich streams that can be used as low-cost carbon sources for polyhydroxyalkanoate (PHA) production. In this study, an inoculum collected from an anaerobic reactor of a municipal WWTP was conditioned to suppress methanogenic activity. The heat-shock conditioning method of the inoculum proved to be more efficient than acid and alkaline conditioning methods for methanogen inhibition. Then, the pre-conditioned inoculum was used to determine the acidogenic potential of different wastes: three waste activated sludge (WAS) samples generated at different sludge retention times (SRTs, 2, 7 and 14 days), olive mill wastewater (OMW), glycerol, apple pomace (AP) and winterization oil cake (WOC). Batch tests were performed in quintuplicate at 37°C and pH 7. A higher degree of acidification was observed for high-rate activated sludge (2 days of SRT) (69%), followed by olive mill wastewater (OMW) (43%), while the lowest was for g...
Recovery of acids from anaerobic acidification broth by liquid–liquid extraction
Chemosphere, 2009
In this study, anaerobic acidification of sugar beet processing wastes and subsequent liquid-liquid extraction of produced fermentation metabolites were investigated. The aim of extraction experiments was to asses the influence of pH and extractant (trioctylphosphine oxide (TOPO) in kerosene) concentrations on the recovery of volatile fatty acids (VFAs) from fermentation broth. The effect of TOPO in kerosene concentration was as crucial as the effect of pH on the recovery of VFAs via extraction. Consequently, pH 2.5 was determined as optimum. At this pH, percent recoveries of VFAs were changed from 43% to 98%, depending on the type of the acid extracted (acetic, butyric, propionic and valeric acids) and the concentration of TOPO in kerosene (5-20%). As the concentration of TOPO in kerosene was increased, efficiency of extraction was increased. As a result, highest VFA recoveries (61-98%) were observed at 20% TOPO in kerosene with distribution ratio values ranging between 1.54 and 40.79. At pH 2.5, the increase in TOPO concentration directly increased the chemical oxygen demand (COD) removal efficiencies, as it does for total VFA recovery. Up to 72% COD removals were achieved, at 20% TOPO in kerosene at pH 2.5, while the removal efficiencies remained between 19% and 22% at pH 5.5.
THE USE OF SOLID STATE FERMENTATION FOR FOOD AND FEED PLANT MATERIAL PROCESSING
Veterinarija ir Zootechnika
Abstract. The present study is aimed at selection of the optimal conditions for solid state fermentation of flaxseed, white lupine, defatted soy flours and Jerusalem artichoke tubers and integrated evaluation of the changes of product physico-chemical properties during the processing. The moisture content, pH kinetic and total titratable acidity (TTA) as well as contents of D-(-) and L-(+) isomers of lactic acid, amylolytic and proteolytic activities, excreted by Lactobacillus sakei, Pediococcus acidilactici KTU05-7 and Pediococcus pentosaceus KTU05-8 during submerged (SMF) and solid state fermentation (SSF) of plant products were analysed. The results showed the impact of moisture content of substrate on formation of organic acids and vitality of LAB during SSF in the analysed plant products. The fermented products of 50 % moisture were found to have the lowest values of pH and the highest TTA and content of bacteria. The highest amylolytic activity excreted by L. sakei and P. acid...
Acidogenic Valorisation of High Strength Waste Products from Food Industry
Industrial Waste, 2012
Currently, acidogenic processes are widely spread among bioreactor engineered technology, and are usually designed for customised applications and for particular high strength waste products. Although methane is usually considered the final product of anaerobic degradation, there are some other valuable by-products which can compete with methane and has a market for itself, such as volatile fatty acids (VFA) that can constitute a valuable resource for biodegradable polymer production (poly-hydroxyalkanoates-PHA) or biological nutrient removal. The acidogenic microorganisms have specific physiology, nutritional requirements, optimal pH, growth and substrate uptake kinetics. Although global and two-phase anaerobic processes are well studied, little information exists on adequate design and operation of acidogenic digesters. However, higher kinetic rates for acidogenic metabolism may be the most interesting feature on industrial exploitation of this process.