Fermentation Of Waste Research Articles

Food Waste Fermentation Liquid as a Supplementary Carbon Source for Enhanced Biological Nitrogen Removal from Rural Wastewater

Food Waste Fermentation Liquid as a Supplementary Carbon Source for Enhanced Biological Nitrogen Removal from Rural Wastewater

Enhancement of volatile fatty acids to extremely high content in fermentation of food waste: Optimization of conditions, microbial functional genes, and mechanisms

The engineering application of volatile fatty acids (VFA) production from food waste (FW) can significantly enhance resource utilization. Enhancing VFA production is crucial for advancing this engineering application. This study presented a economically-feasible method to achieve high VFA production from FW: Conducting fermentation at pH 9 and 37 ℃ with addition of 20 % anaerobic sludge significantly increased the conversion of FW to VFAs (80.56 g COD/L, accounting for 87.37 % of the soluble chemical oxygen demand), while also increasing the content of NH4+-N (2658.15 mg/L). Macrotranscriptomic sequencing showed that Anaerosalibacter, Amphibacillus, Wansuia, Clostridiisalibacter, unclassified Tissierellia, Massilibacterium, unclassified Bacteroidales, and Tissierellia were the key active microorganisms for VFA production. The expression abundance of functional enzymes and genes related to VFA production pathways increased during the fermentation. This study significantly advanced the practical application of VFA production from FW, offering both theoretical insights and bacterial resources.

Performance and mechanism of biochar pretreatment on improving short-chain fatty acids production from anaerobic fermentation of waste activated sludge

Performance and mechanism of biochar pretreatment on improving short-chain fatty acids production from anaerobic fermentation of waste activated sludge

Insights into multivalent metal removal-assistant anaerobic fermentation of waste activated sludge: Impact factor identification and mechanism clarification of metal removal

The study investigated the impact factors of metal removal and their role in enhancing anaerobic fermentation of waste activated sludge (WAS), aiming to identify key mechanisms. By optimizing the sludge concentration, it found that a sludge suspension solid range of 10–30 g/L significantly improved the efficiency of anaerobic fermentation, and yielded SCOD of 93.8–177.1 mg/g volatile suspension solid after 8 h, respectively, which was 3.67–4.77 times higher than the control. Correspondingly, the production of short-chain fatty acids (SCFAs) was significantly enhanced. At the optimal sludge suspension solid of 10–30 g/L, the SCFAs were 1.28–1.51 times higher than that of the control. Furthermore, the study evaluated the performance of different metal removal reagents and discovered that microporous COOH reagent outperformed gel SO3H and macroporous SO3H reagent. The macroporous COOH reagent achieved 1.54 and 1.22 times higher SCOD values and significantly enhanced the production of SCFAs, demonstrating its superiority in metal removal and fermentation enhancement. Moreover, the research revealed that sludge concentration and metal removal agent types influenced the activities of key enzymes involved in anaerobic fermentation. Additionally, the macroporous COOH reagent showed the most efficient ability to remove metal ions, contributing to increased nutrient recovery in terms of nitrogen (NH4+-N) and total phosphorus (TP) release during the acidification process. In summary, the enhancing mechanism of metal removal-assistant anaerobic fermentation was discussed from the sludge floc concentration, the skeleton structure and the ion exchange group type. The identified mechanism significantly improves fermentation efficiency and facilitate the organic recovery, representing an innovative approach for wide application in WAS management and resource recovery.

Exploring the influence of moisture stress on microbial-driven organic acid synthesis in potato waste fermentation

Anaerobic fermentation of potato leaves and stems for organic acid synthesis, serving as food additives, faces impediments due to misconceptions about the effects of moisture stress on the acid-synthesizing microbiome. An ingenious method, avoiding interference from microbiome and nutrient integrations, was employed in the present study. Results showed that increasing the moisture level from 60 % to 75 % significantly improved lactic acid (182.64 %), acetic acid (163.55 %), propionic acid (1960.43 %), nonprotein nitrogen, free amino acid and ammonia levels but reduced pH value and water-soluble carbohydrate and hemicellulose levels. Microbiologically, the high-moisture groups enriched Lactiplantibacillus, Levilactobacillus and Enterobacter, upregulated glycolysis, nitrogen, pyruvate and propanoate metabolisms, and activated genes for acid-producing and ammonia-forming enzymes. Notably, Lactiplantibacillus and Enterobacter prevailed in glycolysis and nitrogen metabolism, respectively, and Levilactobacillus was more prominent in pyruvate and propanoate metabolism under high-moisture conditions. Collectively, a moisture level of 75 % benefited organic acid synthesis from potato waste via anaerobic fermentation.

Efficient conversion from food waste to composite carbon source through rapid fermentation and ceramic membrane filtration

Anaerobic fermentation of food waste (FW) produces a broth rich in small-molecule organic substances, which has the potential as a composite carbon source for denitrification in wastewater treatment. In this study, the idea was tested by optimizing the fermentation process at different hydraulic residence time (HRT), refining fermentation broth through ceramic membrane filtration, and comparing the performance of fermentation filtrate and other commercial carbon sources. A short HRT of 3 days was a suitable fermentation condition with 88% polysaccharide degradation. Acetic acid contributed 40% of soluble chemical oxygen demand in the fermentation broth, followed by ethanol, propanol, lactic acid, and propionic acid, and the five products accounted for 80%. Ceramic membrane filtration can recover more than 70% of dissolved organic matter and more than 60% of small molecular organic matter and simultaneously remove 99% of SS, 41% of total nitrogen, and 62% of total phosphorus. At the rapid degradation stage, the denitrification rates reached 6.68–10.39 mg NOx−-N/(g VSS·h), which was on par with commercial carbon sources. The short fermentation and the rapid membrane separation were integrated to create an efficient treatment system, which provided a feasible pathway to utilize FW combining wastewater treatment.

Comparison of Black Soldier Fly (BSF) Maggot Nutrition with Different Culture Media

Maggot Black Soldier Fly (Hermetia illucens) is one of the natural feeds widely used by fish farmers. Maggot has a high nutritional content so that it is in great demand by the community. This study aims to determine the nutritional value contained in maggot cultured using different culture media. The culture media used in this study include fermentation of tofu waste and fermentation of fish waste. Fermentation of culture media was carried out for 7 days using EM4, sugar and water. The parameters analyzed in this study included protein content, fat content, water content, ash content and carbohydrates. The results showed that maggots cultured using fish waste fermentation culture media had a higher protein content compared to tofu waste fermentation culture media. The nutritional value of the fish waste fermentation treatment was 33.94% protein, 8.13% moisture content, 2.85% ash content, 3.31% fat and 51.16% carbohydrate.

Hexanoic acid production from anaerobic fermentation of Chinese cabbage waste with exogenous lactic acid as electron donor

The lack of electron donors is one of the key factors hindering hexanoic acid production from anaerobic fermentation. In this study, three different types of lactic acids were supplemented as exogenous electron donors to the anaerobic fermentation system of Chinese cabbage waste (CCW). The yields of hexanoic acid in the reactors supplemented with CCW lactic acid pre-fermentation broth (PFB), lactic acid diluent (LAD) and chemical lactic acid (LA) were 6996.8 mg COD/L, 4534.8 mg COD/L and 6777.1 mg COD/L, respectively. Compared with the reactor supplemented with LA, the electron efficiency of hexanoic acid in reactor supplemented with PFB increased by 188 %. Supplementing PFB shifted the microbial communities towards a direction favorable to hydrolysis and chain elongation, thereby facilitating the synthesis of hexanoic acid.

Lysozyme coupling protease pretreatment to relieve the humic acid inhibition on excess sludge anaerobic fermentation

The asynchronous dosed protease and lysozyme combination pretreatment was proved to be effective in enhancing the anaerobic fermentation of waste activated sludge (WAS). However, humic acid (HA) in the sludge could interact with hydrolase and restrain the hydrolysis efficiency, thus inhibiting short-chain fatty acids (SCFAs) production. This study investigated the effectiveness and mechanism of enzymatic pretreatment against HA. Results showed that the enzyme cocktail method increased the extracellular bioavailable contents by 34 %, which raised SCFAs production by 89.69 % (1269.65 mg COD /L). The balanced ratio of hydrolysis and fermentation communities suggested that the small molecular organics generated by the hydrolysis community could be sufficiently utilized by fermentation communities. The metabolism of amino acids and glucose was facilitated, and the activities of key enzymes were enhanced. These results clarified the effect of asynchronous enzyme cocktail pretreatment against HA inhibition and contributed to SCFAs production, which offered fresh perspectives on carbon recovery.

Effect of D-limonene on volatile fatty acids production from anaerobic fermentation of waste activated sludge under pH regulation: performance and mechanisms

D-limonene extracted from citrus peels possesses an inhibitory effect on methanogenic archaea. This study is aimed to bridge the research gap on the influence of D-limonene on volatile fatty acids (VFA) production from waste activated sludge (WAS) and to address the low VFA yield in standalone anaerobic fermentation of WAS. When the initial pH was not controlled, 1.00 g/g TSS D-limonene resulted in a VFA accumulation of 1175.45 ± 101.36 mg/L (174.45 ± 8.13 mgCOD/gVS). When the initial pH was controlled at 10 and the D-limonene concentration was 0.50 g/g TSS, the VFA accumulation reached 2707.44 ± 183.65 mg/L (445.51 ± 17.10 mgCOD/gVS). The pH-regulated D-limonene treatment enhanced solubilization and acidification, slightly inhibited hydrolysis, and significantly suppressed methanogenesis. D-limonene under alkaline conditions can increase the relative abundance of Clostridium_sensu_stricto, significantly enhancing acidification. Moreover, it markedly inhibited methanogenesis by particularly reducing the relative abundance of Methanothrix that was responsible for acetate consumption, thus favoring the accumulation of VFA. The research reveals the potential mechanism of pH regulation and D-limonene on anaerobic fermentation acid production, providing a theoretical basis for improving the acid production performance of the anaerobic fermentation of WAS.

Enhancing selective NH4+ recovery from wastewater using modified zeolite-based flow electrode capacitive deionization

Despite flow-electrode capacitive deionization (FCDI) is an emerging technology for desalination, contaminant removal, and resource recovery, the application of conventional FCDI in wastewater treatment is hindered by the electrode selectivity and material costs. In this study, we synthesized a low-cost ammonium (NH4+) adsorption electrode material by modifying zeolite using ethylenediaminetetraacetic acid disodium salt (EDTA-2Na). The flow electrode prepared by the mixture of EDTA-zeolite and carbon black exhibits a high selectivity and adsorption capacity for the recovery of NH4+ from wastewater. The NH4+ in wastewater passes through the ion exchange membrane and is rapidly adsorbed by the modified zeolite through ion exchange, while Na+ is retained in the electrolyte. The decrease in NH4+ concentration and the increase in Na+ concentration in the catholyte lead to a significant change in ion concentration gradient across the membrane. Consequently, the transmembrane selectivity between NH4+ and Na+ reached 3.46. We validated the feasibility of NH4+ recovery using FCDI with food waste fermentation supernatant. Under optimal operating conditions, 99.15 % of the NH4+ in the fermentation supernatant was removed, and 95.92 % of the NH4+ in the electrolyte was stored in the EDTA-zeolite. By gravitational settling, the NH4+-rich modified zeolite was separated from carbon black and could be utilized as nitrogen fertilizer. Meanwhile, the mixture of carbon black and brine was used to prepare a fresh electrode suspension. In brief, the FCDI system exhibits a satisfying NH4+ recovery performance and demonstrates a sustainable wastewater resource recovery strategy.

Biorefinery-oriented pyrolysis and anaerobic fermentation synergies: Leveraging biomass tar for enhanced chemical production from food waste

The carboxylic platform via mixed culture anaerobic fermentation holds significant potential for biorefinery applications. However, effective and economical methanogenesis inhibition remains crucial for maximizing production efficiency. This study investigates the use of biomass tar, derived from the pyrolysis of rice husk, as a methanogenesis inhibitor to enhance the anaerobic fermentation of food waste and boost the production of reduced fatty acids. The experimental results demonstrated that adding 5.0 g/L of tar achieved the highest hydrogen production, reaching 65.0 mL/g VS. Furthermore, increasing tar concentrations led to higher yields of reduced and longer-chain fatty acids, with butyrate production peaking at 726.8 mg COD (chemical oxygen demand)/g VS (volatile solid) with 30.0 g/L tar, and caproate at 128.6 mg COD/g VS with 10.0 g/L tar. GC-MS analysis identified phenolic compounds and furan derivatives as the primary inhibitory agents, which gradually degraded during fermentation. Microbial community analysis revealed that the tar-based inhibitors effectively suppressed dominant methanogenic archaea, including Methanothrix, Methanobacterium, and Methanosarcina, while promoting the enrichment of chain-elongating bacteria such as Clostridium_sensu_stricto and Clostridium_IV. This study suggests that integrating biomass tar from pyrolysis with anaerobic fermentation can serve as a highly efficient biorefinery approach, fully utilizing diverse organic wastes for sustainable energy production.

Utilization of water chestnut waste for biohydrogen production and enhanced power generation by stacked microbial fuel cell

A novel two-stage approach combining dark fermentation with microbial fuel cell (MFC) technology is proposed which enable biohydrogen production and bioelectricity generation from residual substrate energy. In the present study, batch fermentation of water chestnut waste using Enterobacter aerogenes (MTCC 2822) resulted in the production of biohydrogen. In the batch process, the highest production was 3.2 L/L. Further, single-parameter optimization and multi-parameter optimization were conducted via Response Surface Methodology (RSM) using the Central Composite Design (CCD) model. The maximum biohydrogen reached 3.44 g/L with 55% COD removal. The biohydrogen yield was 7.163 g H2/kg CODreduced with a maximum production rate of 712 mL/L/h. Further, the waste fermentation medium or spent media was used as a substrate in a Microbial Fuel Cell (MFC) to produce power using Pseudomonas aeruginosa PA1_NCHU as inoculum. MFCs were operated with various concentrations of phosphate buffer in the anolyte. As the output is limited in a single MFC, MFCs were operated in parallel stacks to increase power output. A maximum of 28% increase in the power density was observed in stacked MFCs. The energy recovered from the dark fermentation process was around 10.39% and a single MFC was around 10.67%. Hence, this study highlights the innovative use of agricultural waste and the effective combination of dark fermentation with stacked MFC, presenting a sustainable method of maximizing biohydrogen production and bioelectricity from spent media. By leveraging stacked MFC configuration, the potential of higher power output is demonstrated, underscoring the significance of this integrated system for energy recovery.

Assessing the aerobic/anoxic enrichment efficiency at different C/N ratios: pilot scale polyhydroxyalkanoates production from waste activated sludge

Polyhydroxyalkanoates (PHA) can be produced using fermentation products of an excess sewage sludge fermentation process. An efficient method to enrich a PHA-producing community is an aerobic-feast/anoxic-famine enrichment strategy. The effect of different carbon to nitrogen (C/N) feed ratios of 1, 2 and 3.5 g COD/g N on the process performance was studied. The study was executed on a pilot plant scale using fermented waste activated sludge as the organic carbon source. The system's performance was monitored in terms of removing contaminants, producing PHA, and reducing N2O emissions. The results indicated that a lower C/N ratio results in lower PHA production, with PHA content in the sludge of 20, 24 and 36 % w/w for C/N ratios of 1, 2 and 3.5 g COD/g N, respectively. At the lowest C/N ratio, the highest nitrite accumulation rate (77%), nitrification efficiency (89%) and denitrification efficiency (89%) were observed, but the N2O production was also the highest (0.77 mg N2O-N/L). The long-term comprehensive monitoring carried out in this study revealed high carbon and ammonia removal efficiencies (never below 80%) despite the C/N shifts and high COD and ammonia concentrations. At the same time, the system showed relatively low PHA production and high environmental impact in terms of high gaseous N2O emission. These findings question the sustainability of the aerobic-feast/anoxic-famine enrichment strategy for PHA production in full-scale plants.

Innovative Use of Eco-Enzymes for Domestic Wastewater Purification

The rapid pace of urbanization and the resultant increase in waste generation have significantly escalated the challenges associated with managing organic waste. In line with contemporary sustainable practices, it is imperative to recycle and repurpose waste effectively. This study investigates the use of eco-enzyme, an environmentally friendly product derived from fruit and vegetable scraps, along with natural sweeteners, in the treatment of domestic wastewater. The study assessed the impact of eco-enzyme concentrations at 15% and 20% over a five-day period. Results demonstrated that treated wastewater met irrigation standards after the treatment period. Parameters such as acidity, dissolved solids, biochemical oxygen demand, chemical oxygen demand, and microbial counts were analyzed. The 15% eco-enzyme solution reduced biochemical oxygen demand by 90.54% and chemical oxygen demand by 83.33%, while the 20% solution achieved reductions of 94.20% and 86.34%, respectively. Dissolved solids levels were reduced to 412 ppm and 422 ppm for the 15% and 20% solutions, respectively, and microbial counts decreased significantly. However, the study is limited by the short duration of the treatment period and the scope of the parameters analyzed, which may not fully capture the long-term effectiveness and broader environmental impacts of eco-enzyme use. This research underscores the potential of eco-enzyme technology in enhancing wastewater treatment processes, promoting environmental sustainability, and alleviating the burden on waste management systems. The eco-enzyme production process is straightforward and accessible, involving the fermentation of kitchen waste, and can be readily adopted in both urban and rural settings. Further research is recommended to optimize the fermentation process, reduce digestion time, and explore the broader applications of eco-enzymes in fields such as agriculture and domestic cleaning.

Exploring the effect of lipid loading on acidogenic fermentation of food waste: Insights from microbiome, quorum sensing and carbon metabolic pathway

The high lipid loading in food waste (FW) is widely regarded as one of the main bottlenecks in the traditional anaerobic digestion, but the effect of lipid on FW acidogenic fermentation has been historically ignored. This study attempted to reveal the influence of lipid loading on volatile fatty acids (VFAs) production and the corresponding synthesis mechanisms during FW acidogenic fermentation. The VFAs production reached 27.10 ± 1.00 g COD/L when the lipid loading comprised 25 % of the FW dry weight, increasing by 36.88 % compared to the CK group. Lactobacillus, with a relative abundance of 59.43 %, was the predominant genus under lipid loading. In quorum sensing (QS) system, the relative abundance of luxS that is involved in the biosynthetic pathway of the Autoinducer-2 (AI-2) signal molecule increased from 0.066 % to 0.10 % in the presence of lipid. The relative abundance of Genetic Information Processing increased from 16.36 % to 24.25 % under lipid loading, with up-regulation of Translation and Replication and repair. Lipid loading not only promoted the conversion of acetyl-CoA to acetic acid, as evidenced by a 1.36-fold increase in pta gene abundance, but also concurrently suppressed the consumption of acetic acid, reflected in the 96.83 % and 77.16 % decreases in ALDH and aldB abundance, thus accumulating acetic acid. Carbon emission was also constrained under lipid loading, in which the conversion from formate to CO2 and passing Tricarboxylic acid (TCA) cycle were restricted over 60 %. Together, lipid loading in FW represents a potential strategy for enhancing VFAs production in FW acidogenic fermentation.

Solid-State Fermentation of Cereal Waste Improves the Bioavailability and Yield of Bacterial Cellulose Production by a Novacetimonas sp. Isolate.

Cereal wastes such as rice bran and cereal dust are valuable yet underutilised by-products of grain processing. This study aimed to bio-convert these wastes into bacterial cellulose (BC), an emerging sustainable and renewable biomaterial, via an inexpensive solid-state fermentation (SSF) pre-treatment using three mould isolates. Medium substitution by directly using untreated rice bran or cereal dust did not significantly increase the yield of bacterial cellulose produced by Novacetimonas sp. (NCBI accession number PP421219) compared to the standard Hestrin-Schramm (HS) medium. In contrast, rice bran fermented with Rhizopus oligosporus yielded the highest bacterial cellulose (1.55 ± 0.6 g/L dry weight) compared to the untreated control (0.45 ± 0.1 g/L dry weight), demonstrating an up to 22% increase in yield. Using the SSF process, the media production costs were reduced by up to 90% compared to the standard HS medium. Physicochemical characterisation using SEM, EDS, FTIR, XPS, XRD, and TGA was performed to gain insights into the internal structure, morphology, and chemical bonding of differently produced BC, which revealed comparable biopolymer properties between BC produced in standard and waste-based media. Hence, our findings demonstrate the effectiveness of fungal SSF for transforming abundant cereal waste into BC, providing a circular economy solution to reduce waste and convert it into by-products to enhance the sustainability of the cereal industry.

Preparation and characterization of biochar from four different solid wastes and its ampicillin adsorption performance.

The integration of biochar (BC) production from organic waste with ampicillin (AMP), an emerging pollutant, adsorption is a novel and promising treatment approach. In this study, peanut shells, coffee grounds, digestates, and oyster shells were used for BC production. Among these, the use of anaerobic digestate from food waste fermentation to produce extracts for antibiotic adsorption is relatively unexplored. The pyrolysis temperature was determined using thermogravimetric analysis (TGA) and the materials were characterized with BET, SEM, FTIR, and XRD. The TGA results indicate that PSB, CRB, and DSB underwent pyrolysis involving cellulose, hemicellulose, and lignin, whereas OSB underwent crystal formation. Characterization revealed that DSB has more functional groups, a superior mesoporous structure, appropriate O/C ratio, and trace amounts of calcite crystals, which are favorable for AMP adsorption. Adsorption experiments demonstrate that all four materials adhere to the Freundlich and Langmuir isotherm and Elovich kinetic models, indicating predominant physical adsorption, with some chemical adsorption also present. Thermodynamic studies demonstrate that BC is spontaneous during adsorption and is a heat-absorbing reaction. DSB exhibits the strongest AMP adsorption. A 53.81mgg-1 adsorbance was obtained at a dosage of 150mg, pH = 2, and 60°C. This study introduces innovative approaches for managing waste types and provides data to support the selection of suitable solid wastes for the preparation of BC with excellent adsorption properties. Furthermore, it lays the groundwork for future studies aimed at enhancing the AMP treatment efficacy.

Nutritional Requirements and Fermentation Condition for Acetic Acid Production From Agricultural Fruit Waste

AbstractStudies on agricultural fruit waste fermentation for acetic acid production have focused on understanding its nutrient requirements. The present systematic literature review aimed to assess the potential and additional nutrients necessary for optimised acetic acid production from fruit waste. Fermentation conditions and techniques employed for the alcoholic and acetous fermentation stages were also evaluated to establish their significant effects on acetic acid yield.

Enhancing medium-chain fatty acids production via alkyl polyglucose modulation of electron acceptor generation, microbial community and metabolic traits in anaerobic fermentation of waste activated sludge

Production of medium chain fatty acids (MCFAs) through anaerobic fermentation is an essential pathway for efficient resource recovery and utilization of waste activated sludge (WAS). In this study, a novel strategy utilizing polyglucose (APG) to enhance MCFAs production from WAS by anaerobic fermentation was proposed. The results showed that the maximum MCFAs production reached 14745.0 mg COD/L with 0.3 g APG/g TSS, which was 20.2 times of that without APG treatment. The transformation of intermediates demonstrated that APG promoted the generation of electron acceptors (i.e., short-chain fatty acids) and conversion of substrate to MCFAs. Microbial community analysis indicated that APG selectively enriched microbe involved in hydrolysis, acidogenesis and chain elongation (CE). Also, the presence of APG had a negative impact on methanogens and potential excessive ethanol oxidation (EEO) microbe, which were competitors of CE bacteria in mixed-culture system. Metagenomic analysis showed an increase in relative abundance of genes encoding metabolic functions responsible for hydrolysis, acidogenesis, CE and energy generation, thus maintained high microbial activity in MCFAs biosynthesis. These enhanced metabolic functions were accompanied by a reduction in relative abundance of genes encoding methanogenesis and EEO metabolism, which together result in boosting the efficiency of substrate and energy flow to MCFAs production. This study presents a promising approach to improve the biotransformation of polysaccharides and proteins from WAS into MCFAs.