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[Display omitted] • Methane yield was increased 104.2% by thermal-netural protease pretreatment. • The release and degradation properties of organic matter were improved. • Functional microorganisms were enriched by thermal-netural protease pretreatment. • Thermal-netural protease pretreatment enhanced the activities of key enzymes. Pretreatments to improve the efficiency of anaerobic digestion (AD) have gained more attention. The efficiency and mechanism of neutral protease (NP) integrated with other methods remain unclear. This study investigated the efficacy of thermal, alkaline and ultrasonic technologies integrated with NP as the pre-treatments for AD of food waste and dewatered sludge. Results showed the thermal method integrated with NP (TH-NP) was the most effective, achieving a 104.2% improvement in methane production. In this case, TH-NP increased soluble chemical oxygen demand and protein concentrations by 8.6% and 39.8%, respectively. Microbial community analysis indicated that TH-NP promoted the symbiosis between Woesearchaeales and hydrogenotrophic methanogenesis. Furthermore, the PICRUSt2 analysis revealed that TH-NP increased the activities of most enzymes in the acetate and propionate metabolic pathways. In summary, TH-NP is more effective in increasing the AD efficiency compared to other combined pretreatments. This study provides theoretical support for protease-induced pretreatment technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comparison of contamination levels and BMP of bio-waste from different sources. • Cu and Zn were the main trace metals found in bio-waste, regardless of its source. • Plastics were the most recurrent physical inorganic impurity. • Depackaged food waste from processing plants presented low contamination levels. This study evaluated the anaerobic digestion suitability of bio-waste from different sources by comparing their biochemical methane potential (BMP), biodegradability (BI), and content of contaminants (heavy metals and physical impurities) − an often-overlooked factor but one of particular concern in bio-waste. Predominant heavy metals included Cu and Zn, while recurring physical impurities comprised plastics and organic non-biodegradable matter. Food waste from food processing plants were most suitable, exhibiting low contamination and high biogas conversion (BMP > 549 NmLCH 4 /gVS and BI > 86 %). Conversely, organic fractions from mechanical biological treatment were highly contaminated, while green waste displayed low biogas conversion (BMP < 368 NmLCH 4 /gVS and BI < 72 %). Food waste from households and medium/large-sized producers also demonstrated high biogas conversion, but variable contamination levels could compromise their suitability. Assessing contaminants alongside BMP and BI provides a comprehensive approach for selecting suitable bio-waste feedstocks that can be introduced in biogas plants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fenton reagent significantly reduced ARGs and MGEs abundance. • Addition of Fenton reagent restricted the late-phase resurgence of ARGs. • MGEs were responsible for variations in the ARG profiles in C treatment. • Acinetobacter, Corynebacterium, and Clostridium_sensu_stricto_1 were the key hosts of ARGs. Livestock manure harbors antibiotic resistance genes (ARGs), and aerobic composting (AC) is widely adopted for waste management. However, mitigating ARG resurgence in later stages remains challenging. This work aims to curb ARGs rebounding through a Fenton-like reaction during food waste and swine manure co-composting. Results revealed that 0.025 % zerovalent iron (ZVI) + 0.5 % hydrogen peroxide (H 2 O 2) facilitated maximum ARG, mobile genetic elements (MGEs), and 16 s rRNA removal with reductions of 2.68, 2.69, and 1.4 logs. Spectroscopic analysis confirmed Fenton-like reaction and cell apoptosis analysis indicated that 0.025 % ZVI and 0.5 % H 2 O 2 treatment had the maximum early apoptosis, least observed, and normal cells on day 30. Redundancy analysis highlighted the influence of bacterial communities and physicochemical properties on ARGs, with MGEs playing a crucial role in Fenton treatments. Our findings suggest incorporating ZVI and H 2 O 2 in composting can significantly reduce ARGs and enhance waste management practices. [ABSTRACT FROM AUTHOR]

[Display omitted] • 10 wt% PLA packing in FW increases the thermophilic stage of composting by 12 days. • Bacillus, Geobacillus, Caldibacillus dominated at the beginning. • PLA hydrolysis products increase biodiversity at the thermophilic stage. • Fragmentation of PLA packaging after 14 days with a decrease in M n to 5.4 kDa. • High PLA does not affect the quality of the composting product. The increasing use of synthetic biodegradable polymers, such as aliphatic polyesters, has led to a greater need to understand their behavior in an end-of-life scenario as food packaging materials. The aim of this work was to investigate the effect on composting of high to 10 wt% concentration of commercial polylactide packaging in food waste during a 98-day pilot-scale test. Members of the genera Bacillus , Geobacillus , Caldibacillus , Compostibacillus , Novibacillus , Planifilum and Aeribacillus accounted for 77 % of the bacterial community at the initial stage. Significant fragmentation of the polylactide packaging was observed after 14 days, and the appearance of low-molecular weight (approximately 5.4 kDa) hydrolytic degradation products led to an increase in biodiversity and a prolongation of the thermophilic stage by 12 days. The results obtained show the possibility of efficient disposal of food waste with high concentration of polylactide packaging under industrial composting conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-solid AnMBR efficiently processed food waste with a 5% lipid content. • With rising lipid ratios, limited stearic acid conversion triggers system collapse. • Lowest microbial growth rate restricts stearic acid's kinetic conversion. • Elevated lipid level reduces enzymes related to β-oxidation in LCFAs degradation. This study investigated the effects of varying lipid ratios on the anaerobic co-digestion of high-lipid food waste (FW) in a mesophilic anaerobic membrane bioreactor (AnMBR). At a lipid concentration of 5 %, optimal biogas production (3.84 L/L/d) and lipid removal efficiency (78 %) were achieved; however, increasing lipid concentrations resulted in significant accumulations of long-chain fatty acids (LCFAs) and volatile fatty acids (VFAs). Batch tests further demonstrated the impact of various types of LCFAs, with stearic acid showing the slowest microbial growth rate (0.033d-1), confirming its role in the accumulation of acetate-dominated VFAs, potentially limiting the methanogenesis process at elevated lipid levels. Furthermore, at 8 % lipid content, the downregulation of key LCFA degradation enzymes and dominance of hydrogenotrophic methanogens indicated adverse conditions. The importance of the intricate interplay between LCFA degradation kinetics and microbial community for the system efficiency was evidenced, offering insights for optimizing and managing high-lipidic wastes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microplastics and phthalate were the highest in food waste extruded biogas residue. • Microplastics with size of < 0.2 mm in each stage exceeded 70 %. • Positive correlations were found between microplastics and phthalate. • Microorganisms with microplastics degradation capabilities were present. Food waste (FW) and its biogas residue were considered as sources of terrestrial microplastics (MPs) and phthalic acid esters (PAEs) contamination. However, there was a lack of research and understanding of the MPs and PAEs pollution problem in FW dry anaerobic digestion process (DADP). The MPs and PAEs in three stages of the DADP with the largest monomer disposal scale in China were identified. At the biogas residue extrusion stage, MPs abundance and PAEs concentration reached the highest values, which were 3.63 ± 0.45 × 103 N·kg-1 and 3.62 ± 0.72 mg·kg-1, respectively. Furthermore, there was a significant positive correlation between MPs and PAEs throughout the process (p < 0.05). Although bacteria and fungi with plastic degradation potential were present in all stages, the contamination problem of MPs and PAEs cannot be completely solved through DADP. This study provides a scientific basis for preventing and controlling the pollution of MPs and PAEs. [ABSTRACT FROM AUTHOR]

[Display omitted] • M. elsdenii enhanced lactic acid conversion to H 2 in the strain mixtures. • M. elsdenii itself achieved up to 3-fold higher H 2 than Clostridium strains. • The addition of pretreated sludge boosted H 2 production in the strain mixtures. • The optimal mixture ratio of M. elsdenii and Clostridium produced 1739 mL H 2 /L. Lactic acid has been applied as a precursor for hydrogen (H 2) production from substrates rich in lactic acid bacteria (LAB), focusing on microbial interactions between producing and consuming LAB tested with model substrates. Therefore, this study evaluated the effect of single and combined lactic acid-consuming bacteria on mesophilic H 2 production in batch tests from lactic acid from fermented food waste (FW). Megasphaera elsdenii , Clostridium beijerinckii , and Clostridium butyricum were inoculated at different ratios (v/v). Additionally, thermal pretreated sludge (TPS) was added to the strain mixtures. The highest production was obtained with M. elsdenii , C. beijerinckii , and C. butyricum (17:66:17 ratio), obtaining 1629.0 mL/L reactor. The optimal mixture (68:32:0 of M. elsdenii and C. beijerinckii) enriched with TPS reached 1739.3 ± 98.6 mL H 2 /L reactor , consuming 98 % of lactic acid added. M. elsdenii and Clostridium strains enhance H 2 production from lactic acid as they persist in a microbial community initially dominated by LAB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Food delivery boxes are tested for aerobic disintegration and anaerobic degradation. • Boxes made of paper only or with coatings (including polylactic acid) are analysed. • Paper is highly suitable for biological treatments behaving similarly to food waste. • Aerobic disintegration of coated boxes is much slower than that of paper only boxes. • Undigested polylactic acid coating is found in anaerobic semi-continuous tests. This study evaluated the fate of food delivery boxes when subjected to biological treatments, reproducing at the lab-scale the conditions of full-scale plants. Four paper-based boxes were composted: two made of paper only, one coupled with polylactic acid (PLA), and one with a barrier coating. One paper only box and the box with PLA were also investigated for their anaerobic degradability with biochemical methane potential (BMP) and semi-continuous tests. During composting, the boxes were not recognisable inside the compost after four (paper only boxes), eight (box with PLA), and twelve (box with barrier coating) weeks. In BMP tests, the paper only box showed a degradability similar to that of food waste (92 %), while the box with PLA degraded only at 76 %. Furthermore, undigested pieces of PLA were found in semi-continuous tests. Accordingly, paper resulted suitable for biological treatments, while the presence of PLA or other barrier coatings can be critical. [ABSTRACT FROM AUTHOR]

[Display omitted] • TEA of bulk agent (BA) ratios in food waste composting facilities was investigated. • 10% BA is an optimal choice for the composting facility when fixed reactor volume. • 20% garden waste has the most economic feasibility when fixed treatment capacity. • Fertilizer prices, subsidies, and processing capacity are key profitability factors. • Organic matter and nutrients in compost products to determine fertilizer market value. Techno-economic assessment (TEA) of a valorization of bulking agent (BA) ratios on the food waste compost value chain is made to assess economic feasibility. TEA was performed with two plans (Plan A: existing composting facilities; Plan B: new composting facilities) and each plan was under four scenarios. The BA (i.e. corn stalks, garden waste, and watermelon seedlings) ratio of 5 % (S1), 10 % (S2), 20 % (S3), and garden waste with a ratio of 20 % (S4). Results indicate that S2, with a net present value (NPV) of 128.9 million, represents Plan A's most economically viable scenario. Although the total operating costs of S4 were 18.9 %–23.5 % higher, 25.6 %–42.2 % higher total revenue made S4 have an NPV of 92.9 million, making it the most viable scenario in Plan B. All scenarios show positive NPV within a ± 20 % fluctuation range. Organic fertilizer price, government subsidies, and processing capacity were the key factors influencing NPV. [ABSTRACT FROM AUTHOR]

• PHBH-made rigid packaging can be mesophilically digested, yielding 400 L-CH 4 /kg. • Size reduction of rigid packaging is needed and feasible with commercial shredders. • Successful co-digestion of PHBH with food waste, sewage sludge or swine manure. • PHBH was kinetically compatible with other organic waste. • Hydrogenotrophic methanogenesis was key in all co-digestion scenarios. This study evaluates the anaerobic mesophilic mono- and co-digestion of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) plastic bottles as a proxy for rigid packaging materials. Initial tests showed a 97.3 ± 0.2 % reduction in weight and an observable alteration in the surface (thinning, color fading and pitting) of the PHBH bottles after eight weeks. Subsequent tests showed that PHBH squares (3 × 3 cm) produced 400 NmL-CH 4 /g-VS fed , at a slower rate compared to powdered PHBH but with similar methane yield. Co-digestion experiments with food waste, swine manure, or sewage sludge showed successful digestion of PHBH alongside organic waste (even at a high bioplastic loading of 20 % volatile solids basis), with methane production comparable to or slightly higher than that observed in mono-digestion. Molecular analyses suggested that the type of co-substrate influenced microbial activity and that methane production was mainly driven by hydrogenotrophic methanogenesis. These results suggest the potential for integrating rigid PHBH packaging into anaerobic digesters. [ABSTRACT FROM AUTHOR]

Background: Food waste is a significant global issue, with 1.3 billion tons generated annually, a figure expected to rise to 2.1 billion tons by 2030. Conventional disposal methods, such as landfilling and incineration, present environmental challenges, including methane emissions and pollution. Hydrogen production through dark fermentation presents a sustainable alternative, offering both waste management and renewable energy generation. This study investigates the bacterial synergy and relay mechanisms involved in thermophilic H 2 production using food waste as a substrate., Purpose: The primary aim of this research was to analyze the metabolic pathways and dynamics of functional genes prediction during thermophilic H 2 production from food waste, focusing on the role of bacterial consortia in enhancing H 2 yields., Methods: A continuous stirred-tank reactor (CSTR) was operated using food waste as the substrate and a thermophilic bacterial consortium as the inoculum. The study utilized genomic analysis to monitor changes in bacteriobiome composition over time and to correlate these changes with H 2 production. Volatile fatty acids (VFAs) and H 2 production rates were analyzed using gas chromatography and high-performance liquid chromatography (HPLC). The Kyoto Encyclopedia of Genes and Genomes (KEGG) database was employed to identify functional genes involved in the fermentation process., Results: The study identified key bacterial species, including Caproiciproducens and Caproicibacter, that dominated during the later stages of H 2 production, replacing earlier dominant species such as Clostridium. These shifts in bacterial dominance were strongly correlated with sustained H 2 production rates ranging from 353 to 403 mL·L -1 ·h -1 , with H 2 concentrations between 55 % and 62 % (v/v). Functional gene analysis revealed significant pathways related to polysaccharide degradation, glycolysis, and dark fermentation., Conclusions: This study highlights the importance of bacterial synergy and relay in maintaining continuous H 2 production from food waste under thermophilic conditions. The findings provide insights into optimizing biohydrogen production processes, emphasizing the role of specific bacterial species in enhancing efficiency. These results contribute to the development of sustainable waste management strategies and renewable energy production., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Kyung-Suk Cho reports financial support was provided by National Research Foundation (NRF) of Korea. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

[Display omitted] • OFMSW was valorised to MCCA at specificity of 40% and conversion efficiency of 23%. • Two-stage fermentation enabled almost twofold increase in caproate production. • The maximum caproate concentration reached 4.0 g/L (8.4 gCOD/L) and specificity of 37 %. • Number of reads annotated to FAB exceeded the number of reads assigned to RBO. • The core microbial community belonged to Clostridia, e.g. Caproiciproducens sp. Single-stage fermentation was characterized by low medium chain carboxylic acids concentrations and different mesophilic temperatures had little effect on the process performance, whereas thermophilic conditions and pH 5.5 led to lactate and ethanol accumulation. Two-stage fermentation enabled almost twofold increase in the caproate productivity, that reached 0.8 g/L-d (1.7 ± 0.1 gCOD/L-d) with a caproate concentration of 4.0 g/L (8.4 gCOD/L) at specificity of 37% and led to a reduced release of carbon dioxide. Under pH 6.5 and temperature of 37°C the production of medium chain carboxylic acids required higher concentrations of ethanol. Number of genes annotated to fatty acid biosynthesis pathway exceeded the number of sequences assigned to the reverse β-oxidation pathway. Core microorganisms encoding these pathways belonged to Caproiciproducens, Caproicibacterium and Clostridium. This study provides a valuable insight for valorisation of organic fraction of municipal solid waste into carboxylates in a single- and two-stage systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • H 2 -producing microbes have been isolated from a full-scale anaerobic digestor. • Two selected Clostridium sp. were tested for H 2 production from benchmark substrates. • C. sartagoforme SA1 was adopted for H 2 production from complex organic wastes. • C. sartagoforme SA1 achieved 55 mLH 2 /gVS from sterilized organic waste. • C. sartagoforme SA1 bioaugmentation of organic waste increased H 2 yield by 40%. Bio-hydrogen from organic waste holds promise as renewable energy. However, its large-scale production is limited by technical challenges, with low H 2 yields and the absence of robust microbial strains being the major ones. To address these limitations, H 2 -producing microbes have been isolated from a full-scale anaerobic digestor treating complex organic waste. Clostridium sartagoforme SA1 was selected because of high H 2 yields from glucose, soluble starch, and carboxymethylcellulose. The strain was then tested for H 2 production from the Organic Fraction of Municipal Solid Waste (OFMSW), rich in starch and cellulose, with productions up to 55 mLH 2 g/VS. Additionally, C. sartagoforme SA1 confirmed high H 2 performances even in the presence of OFMSW's indigenous microflora, increasing the H 2 yield by 38 % and highlighting its robustness in a highly competitive environment. This is the first report describing the efficient adoption of a C. sartagoforme strain for bioaugmentation of non-sterile OFMSW towards high H 2 yields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Feed-shifting strategy improved BSFL growth and biodiesel yield. • Biodiesel quality was improved in feed-shifting compared to single feeding systems. • Higher waste reduction ratio achieved with feed-shifting strategy. • Feed-shifting strategy emitted less CO 2 than that of single feeding systems. The aim of this study was to increase the bioconversion efficiency (lipid accumulation) of black soldier fly larvae while simultaneously increasing biodiesel production through a feed-shifting strategy. Feeding with low-lipid feed promoted an increase in larval weight, while high-lipid feed resulted in greater lipid accumulation. Based on this result, a feed-shifting strategy was introduced, which consisted of two stages: first, increasing larval body weight using low-lipid feed, followed by lipid induction for biodiesel production using high-lipid feed. The use of this strategy resulted in an increase in the dry weight of larvae by ≥16 % compared to single feeding systems. This led to a 20 % increase in biodiesel productivity. The waste reduction ratio was enhanced due to the higher bioconversion rate in the feed-shifting strategy compared to that in the single feeding systems. The feed-shifting strategy would contribute to the enhancement of waste-to-energy efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Yeast lipid can have similar FA profile as palm oil and cocoa butter; or PUFA-rich. • The upstream strategies can be synergized, and integrated with innovative DSP. • Lignocellulosic residue, crude glycerol and food waste can be low-cost feedstock. • Co-culture system and cell harvesting through bioflocculation needs to be explored. • Potential concurrent synthesis and recovery of co-products by oleaginous yeast. An increasing global population demands more lipids for food and chemicals, but the unsustainable growth of plant-derived lipid production and an unreliable supply of certain lipids due to environmental changes, require new solutions. One promising solution is the use of lipids derived from microbial biomass, particularly oleaginous yeasts. This critical review begins with a description of the most promising yeast lipid replacement targets: palm oil substitute, cocoa butter equivalent, polyunsaturated fatty acid source, and animal fat analogue, emphasizing sustainability aspects. Subsequently, the review focuses on the most recent advances in upstream methodologies, particularly fermentation strategies that promote circularity, such as waste valorisation, co-cultivation and co-product biosynthesis. Downstream processing methods for minimising energy consumption and waste generation, including bioflocculation, energy-efficient and environmentally friendly cell lysis and extraction, and integrated co-product recovery methods, are discussed. Finally, the current challenges are outlined. Integrating these strategies advances sustainable yeast lipid production for high-value applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • ADFW thermochemical conversion can save energy and reduce carbon emissions. • ADFW thermochemical conversion contributes to the global demand for available fuel. • Plastic-containing ADFW pyrolysis using red mud/copper in CO 2 /CH 4 atmosphere. The thermochemical conversion technology for anaerobic digestate from food waste (ADFW) can reduce waste volume, eliminate pathogens, and recover energy through incineration, pyrolysis, gasification, and hydrothermal transformation. This paper comprehensively reviews the physicochemical features of anaerobically fermented digestate from food waste (FW), digestate treatment methods, and their advantages and disadvantages. In addition, the analysis and application of associated by-products from ADFW thermochemical conversion are also discussed. The main products include biochar, bio-oil, and biogas. Biochar can be used for soil improvement and biomedicine and bio-oil can be used forliquid fuel. Meanwhile, biogas mainly consists of CH 4 , CO 2 , and H 2 and CO, which can be used in petrochemicals, metallurgy, and other fields. The catalytic pyrolysis/gasification for plastic-containing ADFW is proposed by adding iron-based industrial waste (red mud/copper) as catalysts under the CO 2 /CH 4 atmosphere. This review helps to provide new guidelines for the ADFW utilization of desired products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Brewer's spent grain (BSG) and soy whey (SW) were hydrolysed to recover nutrients. • Hydrolysate medium (15% SW-85% BSG) was rich in sugars, N, P, and minerals. • A. protothecoides growth in hydrolysates was comparable to standard medium. • Comparative price range to produce hydrolysates vs. standard medium. • Hydrolysate medium could be applicable to other heterotrophic microalgal processes. To enhance circularity in heterotrophic microalgal bioprocesses, this study completely substituted glucose and Bold's basal medium (BBM) with brewer's spent grain (BSG) and soy whey (SW) hydrolysates. Mild acid hydrolysis conditions of BSG (0.2 M H 2 SO 4 , 130 °C, 36 min) and SW (0.1 M HCl, 95 °C, 30 min) were optimised for glucose release, and their hydrolysates were optimally mixed (15 % SW-85 % BSG) to obtain a medium that best supported Auxenochlorella protothecoides growth. Maximum biomass production (X max) and productivity (P Xmax) obtained in the hydrolysate medium containing 50.75 g/L endogenous glucose (X max : 22.17 g/L; P Xmax : 7.06 g/L/day) were comparable to that in BBM containing 50.44 g/L exogenous glucose (X max : 20.02 g/L; P Xmax : 6.34 g/L/day). Moreover, estimated hydrolysate medium production costs were within an order of magnitude to BBM. Overall, the integrated approach of tailored hydrolytic treatments and complementary side-streams presents a promising technical and economic feasibility, with applications extending beyond A. protothecoides. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pilot scale thermophilic AD of food waste was investigated on site. • Mass balance, process stability and kinetics were investigated. • Addition of trace elements was essential for higher OLR process. • The dominance of Methanoculleus (92.52 %) in high OLR was unique. • The feasibility of thermophilic AD of industrial food waste treatment was confirmed. Thermophilic anaerobic digestion (AD) offers many benefits for food waste treatment but is seldom adopted in industrial plants due to instability issue, particularly under higher loading conditions. This study thus conducted a 160-day continuous operation of a pilot-scale thermophilic AD system on-site. Results from the experiments showed that the system could operate under relatively lower loading but failed when the loading reached up to 5.69 kg·COD/(m3·d). Volatile fatty acids increased to 6000 mg/L at the corresponding hydraulic retention time of 15 days. Trace elements were then introduced, which restored higher process stability by reducing volatile fatty acids to 400 mg/L. The mass balance and materials decomposition resutls revealed the system's strong resilience. Methanoculleus (92.52 %) and Methanomassiliicoccus (6.55 %) were the dominant methanogens, a phenomenon rarely observed in similar thermophilic systems. This system may tolerate more stressful conditions, as the loading limits had not been reached with the addition of trace elements. [ABSTRACT FROM AUTHOR]

[Display omitted] • FW components exert significant impact on FW methane yield. • HPLFW feeds showed significantly higher CH 4 yield than HCFW feeds. • FW CH 4 production can be described by a modified two-component kinetic model. • Element formula of organic content of FW were determined. This study assessed the methane production from food waste (FW) with dominant components of Meat (MFW), Fruit &Veg (VFW), Grain (GFW), Dairy (DFW), and the mixed feed of these components (MixFW). The high protein and lipid content FW (HPLFW) of MFW, DFW, and MixFW showed the methane yields of 337.0 ± 3.0, 307.4 ± 0.8, and 297.1 ± 1.2 ml-CH 4 /gCOD, respectively, while those for the high carbohydrate content FW (HCFW) of VFW and GFW were 238.3 ± 1.2 and 171.2 ± 0.3 ml-CH 4 /gCOD, respectively. A modified two-component kinetic (MTK) model was demonstrated to be the best to describe the methane production kinetics of both HPLFW and HCFW types of feeds. The element balance analysis revealed the element formula of the FW feeds and the methane-conversion organic content. The results obtained from this study showed that the high lipid and animal protein content increased the methane yield and biogas methane composition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anaerobic digestion produces biogas from rice food waste and animal manure. • Temperature, pH, C/N ratio, microbial activity are crucial for biogas production. • Micro-aerobic systems and additives boost biogas yield in anaerobic digestion. Utilization of organic community wastes towards deriving sustainable renewable energy and adequate disposal of the residual has been an important topic of investigation. Anaerobic digestion and co-digestion of rice-derived food waste and animal manure for sustainable biogas generation is crucial from the view-point of community consumption. This paper presents an extensive review of the important and recent contributions in the related areas. The critical physico-chemical parameters involved in such digestion process are analyzed, including temperature, carbon–nitrogen ratio, microorganisms, pH, substrate characteristics, organic loading rate, hydraulic retention time, volatile fatty acids, ammonia, and light/heavy metal ions. Studies implied that the optimum yield of biogas production could be achieved only when the values of the parameters exist in the specific ranges. Few recent studies highlighted the use of emerging techniques including micro-aerobic system, additives, laser radiation, bio-electrochemical field, among others for efficiency enhancement of the digestion process and optimum yield. The entire study provided a set of important conclusions and future research directives are as well proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic loading rate impacts the fermentation products profile but not the yield. • Butyric acid accumulated at 11 gVS/(L·d) shifting towards ethanol at 18 gVS/(L·d). • Waste activated sludge had a greater impact on microbiota than organic loading rate. • Growth of methanogens migrating with the sludge triggered acetate consumption. • Post-fermentation test can be used to forecast of acetic acid-consuming events. Two perturbations were investigated in acidogenic co-fermentation of waste activated sludge (WAS) and food waste in continuous mesophilic fermenters: increasing the organic loading rate (OLR) and changing the WAS. A control reactor maintained an OLR of 11 gVS/(L·d), while a test reactor had a prolonged OLR change to 18 gVS/(L·d). For each OLR, two WAS were studied. The change in OLR led to differentiated fermentation product profile without compromising the fermentation yields (∼300 mgCOD/gVS). At 11 gVS/(L·d), the product profile was dominated by acetic, butyric, and propionic acids while at 18 gVS/(L·d) it shifted to acetic acid, ethanol, and caproic acid. Reverting the OLR also reverted the fermentation profile. The biomass immigration with the WAS changed the fermentation microbial structure and introduced acetic acid-consuming methanogens, which growth was only delayed by the OLR increase. Microbial monitoring and post-fermentation tests can be used for early detection of acetic acid-consuming events. [ABSTRACT FROM AUTHOR]

[Display omitted] • The LA yield of FW fermentation reached 0.91 g LA/g total sugar with 1 % ITs addition. • The mechanism analysis of ITs promoting LA fermentation of FW was demonstrated. • Pyruvate to LA conversion was facilitated by 1 % ITs with a high NADH/NAD+ ratio. • Lactococcus and Lactobacillus were more abundant with ITs addition. • LAB of FW fermentation system can partially remove heavy metals from ITs. In this study, the feasibility of promoting the lactic acid (LA) fermentation of food waste (FW) with iron tailings (ITs) addition was explored. The best LA yield was 0.91 g LA/g total sugar when 1 % ITs were added into the system. The mechanisms for promoting LA production were acidification alleviation effects and reduction equivalent supply of ITs. Furthermore, the addition of ITs promoted carbohydrate hydrolysis, and the carbohydrates digestibility reached 88.85 % in the 1 % ITs group. The ITs also affected the microbial communities, Lactococcus gradually replaced Streptococcus as the dominant genus, and results suggested that Lactococcus had a positive correlation with LA production and carbohydrate digestibility. Finally, the complex LAB in FW had significant effects on heavy metal removal from ITs, and the removal efficiency Cr, As, Pb, Cd, and Hg can reach 50.84 %, 26.72 %, 59.65 %, 49.75 % and 78.87 % in the 1 % ITs group, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • • The novel reactor allows dry anaerobic digestion of food waste (FW) and straw. • • The methane yield of FW and straw co-digestion could reach 494.2 mL CH 4 /g VS. • • FW significantly improved the anaerobic biodegradability of the substrate (85.7%). • • Co-digestion can improve hydrolysis and acid production efficiency. • • The acetotrophic methanogenic pathway significantly affects the methane yield. Gradient anaerobic digestion reactor (GADR) can improve substrate utilization efficiency by solving the problem of the "short circuit" of materials. However, the substrate's composition significantly affects the reactor's performance. This study investigated the impact of food waste (FW) levels on corn straw's dry anaerobic digestion (AD) in a novel GADR. The results show that biomethane production can be improved by coupling urban and agricultural solid waste recycling. The mechanism is to increase the hydrolysis and acid production efficiency, and the abundance of enzymes related to methanogenesis. The maximum methane yield (494.2 mL CH 4 /g VS) and the highest anaerobic biodegradability (85.7 %) were obtained when the FW was added at 60 %. The co-digestion of FW and straw can improve the hydrolysis and acid production efficiency and methane yield, which improves the buffering capacity and stability of the system compared with the single digestion of FW. [ABSTRACT FROM AUTHOR]

[Display omitted] • Food waste anaerobic digestion based on nitrogen-carbon separation was investigated. • Three-phase separation redistributed carbon and nitrogen before anaerobic digestion. • 78.4% of C and 48.3% of N in food waste were separated in the centrifugation. • The main endpoints for C, N, and P are crude oil, fine slag, and biogas slag. • Separation utilization of carbon and nitrogen improve resource recovery level. Anaerobic digestion of food waste can recover carbon in the form of biogas, while the high concentration of ammonia nitrogen in the digestion effluent becomes troublesome. Therefore, some new treatment plants use three-phase centrifugation to separate homogenized food waste into nitrogen-rich fine slag for insect cultivation and carbon-rich liquid for anaerobic digestion. To analyze the effects of the carbon–nitrogen separation, an upgraded plant's material and elementary flows were investigated. The three-phase separation process redistributed carbon and nitrogen, and the biogas slurry was the primary output. The principal endpoint for C was the crude oil, capturing 57.1 ± 13.1 % of the total input; the find slag collected 48.3 ± 6.9 % of the total N input, and the biogas slag accepted 52.9 ± 4.4 % of the P input. The carbon–nitrogen separation strategy can improve digestion efficiency and increase treatment benefits significantly, marking a promising direction for future developments in food waste utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glucose fosters dominance of Clostridium_sensu_stricto_1 , with 235.00 mL H 2 /gVS. • Starch leads to a diverse and stable microbial population, with 234.34 mL H 2 /gVS. • Oil favors fat-degrading Anaerovibrio , hindering H 2 production, with 30.22 mL/gVS. • Propionate accumulation correlates with carbon source complexity. This study investigated how glucose, starch, and rapeseed oil, three common food waste components with diverse molecular and physicochemical characteristics, influenced hydrogen production and microbial communities in dark fermentation under varying carbon/nitrogen (C/N) ratios. The results indicated that glucose and starch groups, significantly increased hydrogen yields to 235 mL H 2 /gVS (C/N = 40) and 234 mL H 2 /gVS (C/N = 40), respectively, while rapeseed oil, with a lower yield of 30 mL H 2 /gVS (C/N = 20), demonstrated a negative impact. Additionally, an accumulation of propionate was observed with increasing carbon source complexity, suggesting that simpler carbon sources favored hydrogen production and bacterial growth. Conversely, lipid-based materials required rigorous pre-treatment to mitigate their inhibitory effects on hydrogen generation. Overall, this study underscores the importance of carbon source selection, especially glucose and starch, for enhancing hydrogen production and microbial growth in dark fermentation, while highlighting the challenges posed by lipid-rich substrates that require intensive pre-treatment to optimize yields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar simultaneously promoted methane production and phosphorus transformation. • 300 °C and 0.075 g∙g−1 of biochar were the optimal temperature and dosage. • BC300 promoted an 18% increase in the proportion of active phosphorus. • Biochar may facilitate the hydrogenotrophic methanogenic pathway. • Synergistic effect of microorganisms increased the proportion of active phosphorus. Biochar has been proved to improve methane production in high solids anaerobic co-digestion (HS-AcoD) of dewatered sludge (DS) and food waste (FW), but its potential mechanism for simultaneous methane production and phosphorus (P) transformation has not been sufficiently revealed. Results showed that the optimal preparation temperature and dosage of sludge-based biochar were selected as 300 °C and 0.075 g·g−1, respectively. Under this optimized condition, the methane production of the semi-continuous reactor increased by 54%, and the active phosphorus increased by 18%. The functional microorganisms, such as Methanosarcina , hydrogen-producing, sulfate-reducing, and iron-reducing bacteria, were increased. Metabolic pathways associated with sulfate reduction and methanogenesis, especially hydrogenotrophic methanogenesis, were enhanced, which in turn promoted methanogenesis and phosphorus transformation and release. This study provides theoretical support for simultaneously recovery of carbon and phosphorus resources from DS and FW using biochar. [ABSTRACT FROM AUTHOR]

[Display omitted] • The combination of AC and CaO 2 achieved superior anaerobic digestion performance. • AC/CaO 2 induced more ROS production and bolstered metabolic activity. • AC/CaO 2 promoted the formation of bio-aggregates. • AC/CaO 2 enabled improved mutualism between facultative bacteria and methanogens. • AC/CaO 2 built a robust enzymatic defense system and unique damage repair strategy. This study examined the combination of activated carbon and magnetite with calcium peroxide in enhancing the anaerobic digestion (AD) performance of food waste (FW). The individual mechanisms of these two approaches were also clarified. The results indicated that AC/CaO 2 achieved the highest specific methane yield of 434.4 mL/g VS, followed by Fe 3 O 4 /CaO 2 (416.9 mL/g VS). Both were significantly higher than other groups (control, AC, Fe 3 O 4 , and CaO 2 were 330.1, 341.4, 342.8, and 373.2 mL/g VS, respectively). Additionally, compared to Fe 3 O 4 /CaO 2 , AC/CaO 2 further increased reactive oxygen species (ROS), thereby enhancing the hydrolytic acidification process. Simultaneously, the higher ROS levels of Fe 3 O 4 /CaO 2 and AC/CaO 2 promoted the formation of microbial aggregates and established a more robust enzymatic defense system and unique damage repair strategy. The research comparatively analyzed the synergistic mechanism of iron-based and carbon-based conductive materials with CaO 2 , providing new perspectives for optimizing the AD of FW. [ABSTRACT FROM AUTHOR]

[Display omitted] • All the feeding conditions were stable for the sufficient support from mineral alkalinity. • VS and COD removal maintained about 80% all along the experiment. • Prokaryotic community decreased in diversity and shifted greatly for PW = 50 %. • PW contents as 40% is TS (13.1% in total weights) was suggested. • Mesophilic co-digestion of PW with FW recovered biomethane as 445 ∼ 350 NL/kg-VS fed. Biomethane recovery from paper waste (PW) was achieved by mesophilic co-digestion with food waste. The feeding material containing 0%, 20%, 40% and 50% of PW in total solids (TS) were investigated in the long-term continuous operation. The results showed that the biogas production, pH, alkalinity and biodegradation of volatile solids (79.8 ± 3.6%) were stable for PW contents no more than 50%. The PW = 50% condition was considered the critical limit for the reasons of pump clogging, sufficient alkalinity (2.0 ± 0.3 g-CaCO 3 /L) and depletion of ammonia. Prokaryotic diversity indices decreased with the increased PW contents. Great shifts were observed in the prokaryotic communities before and after the PW contents reaches 50% as TS (18.4% as total weights). Biomethane recovery yields were deceasing from 445 to 350 NL-CH 4 /kg-fed-volatile-solids. The PW contents as 40% as TS (13.1% as total weights) obtained the optimal performance among all the feeding conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chitinase was successfully immobilized on functionalized magnetic nanoparticles. • Immobilized chitinase significantly enhanced thermal and storage stabilities. • Immobilized chitinase hydrolyzed chitin capably yielding di- N -acetyl chitobiose. Described is chitinase immobilization on magnetic nanoparticles (MNPs) as biocompatible support for enzymatic production of di- N -acetyl chitobiose from chitin waste. Chitinase immobilization was feasible with an immobilization yield of 88.9 ± 1.6 % with 97.8 ± 1.0 % retention of activity and compared to free enzyme work, immobilization conferred better thermal and storage stability. As practical benefit the attachment to magnetic nanocarriers enabled easy enzyme recovery after repeated application runs and thus sustainable reuse. In fixed state chitinase retained a remarkable 39.7 ± 2.6 % of the starting activity after 16 reaction cycles. Furthermore, immobilized chitinase showed higher catalytic activity than free chitinase in converting shrimp shells and squid-pens chitins into di- N -acetyl chitobiose in a single-step reaction. The final yield of purified compound was 37.0 ± 1.2 % from shrimp shells and 61.1 ± 0.5 % from squid-pens chitin. In conclusion, an efficient MNP-based chitinase immobilization system with the potential for large-scale production was developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Food waste hydrolysate (FWH) could act as a defoamer in the activated sludge process. • Fatty acids, oils, and solid particles in FWH played essential roles in defoaming. • Long-chain unsaturated fatty acids were mainly responsible for the defoaming. • FWH provided external carbon sources for the activated sludge process. The activated sludge process is the most widely used technology for treating municipal wastewater. However, thick foam often occurs in activated sludge process. Here, we reported for the first time the effect of food waste hydrolysate (FWH) as an external carbon source on defoaming in activated sludge process. The study found that FWH was effective in defoaming at a wide dose range of 50–1600 mg/L total solids, as exhibiting that the foaming tendency of FWH-added foam mixed liquor was reduced to 0 mL-foam/mL-air·min from initial 0.171 mL-foam/mL-air·min in the control without adding FWH with 100 % of defoaming efficiency. Fatty acids, oils, and solid particles in FWH jointly contributed to the deformation. Among these factors, the concentration of long-chain unsaturated fatty acids was mainly responsible for the defoaming. This work provides a cost-effective strategy to solve the foaming problem in activated sludge process as well as providing external carbon sources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lactate-driven dark fermentation (LD-DF) of real organic waste was studied. • Heterogeneous OFMSW was suitable for bioH 2 production via LD-DF. • A shortage of carbs and/or a high pre-acidification degree inhibits H 2 production. • pH and initial solids loading have a strong impact on the OFMSW LD-DF. This study evaluated the hydrogen production potential through lactate-driven dark fermentation (LD-DF) of organic wastes from solid waste treatment plants, including the organic fraction of municipal solid waste (OFMSW), mixed sewage sludge, and two OFMSW leachates. In initial batch fermentations, only OFMSW supported a significant hydrogen yield (70.1 ± 7.7 NmL-H 2 /g-VS added) among the tested feedstocks. Lactate acted as an important hydrogen precursor, requiring the presence of carbohydrates for sequential two-step lactate-type fermentation. The impact of operational pH (5.5–6.5) and initial total solids (TS) concentration (5–12.5 % w/w) was also evaluated using OFMSW as substrate, obtaining hydrogen yields ranging from 6.6 to 55.9 NmL-H 2 /g-VSadded. The highest yield occurred at 6.5 pH and 7.5 % TS. The LD-DF pathway was indicated to be present under diverse pH and TS conditions, supported by employing a specialized microbial consortium capable of performing LD-DF, along with the observed changes in lactate levels during fermentation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Urban food waste—green infrastructure nexus is feasible. • Food waste digestate significantly promoted green roof plant growth and functions. • Food waste digestate is better than digestate biochar in green roof promotion. • 20% performed better than 10% both in digestate and digestate biochar. Waste—Green Infrastructure Nexus is crucial to mitigate carbon emissions in waste disposal and promote eco-functions of green infrastructure in a circular bio-economy. Our purpose is to verify the feasibility of the nexus via "food waste anaerobic digestion — digestate/digestate biochar — green roof promotion". The results found that food waste digestate and digestate biochar significantly promoted green roof plant growth, evapotranspiration, rainwater retention, runoff reduction, and prevention of nutrient leaching. Digestate treatments were better than digestate biochar for the green roof promotion. The promotion ranked consistently with 20 % digestate > 10 % digestate > 20 % digestate biochar > 10 % digestate biochar > control in stolon growth, leaf emergence, branching of Paspalum vaginatum , green roof establishment, rainwater retention, runoff reduction, and the leaching of nitrogen, phosphorus, potassium. This study demonstrated that food waste could be regenerated to promote urban green infrastructure to form a circular bio-economy by the Waste—Green Infrastructure Nexus. [ABSTRACT FROM AUTHOR]

[Display omitted] • FNA pretreatment can significantly improve the solubilization of organic waste. • pH change within the system can adversely impact the FNA pretreatment performance. • Effective FNA concentration may decrease due to NO 2 – consumption by denitrifiers. • FNA-pretreated organic waste does not always show a higher biogas production in AD. • FNA at 1.0–5.2 mg FNA-N/L effectively controlled H 2 S-odor in the organic wastes. This work investigated the effectiveness of free nitrous acid (FNA) in enhancing organic waste solubilization to improve biogas production in anaerobic digestion (AD). The results indicated that FNA pretreatment can enhance soluble organic content and control H 2 S odor in tested organic wastes, including food waste, sewage sludge, and their combination. However, a significant decrease (>50 %) in FNA concentration was found in the reactors, possibly due to denitrifier-driven NO 2 – consumption. Biochemical methane potential (BMP) tests showed a 25 ± 8 % enhancement in CH 4 production in the reactors fed with mixed substrate pretreated with 2.9 mg FNA-N/L. However, the presence of NO 2 – (325.6–2368.0 mg N/L) in some BMP reactors, due to carryover from FNA pretreatment, adversely affected CH 4 production (>55 %) and prolonged lag time (>4.2 times). These findings are valuable for researchers and practitioners in waste management, offering insights for implementing FNA pretreatment to enhance the biodegradability of organic wastes in AD. [ABSTRACT FROM AUTHOR]

[Display omitted] • A stable continuous AnDMBR was first applied in codigestion with CS and FW. • Lignocellulase addition improved the CH 4 yield and lignocellulose degradation rate. • Solid-liquid separation efficiency of DM enhanced with lignocellulase as additive. • The addition of enzymes promotes the acetylation ability of microbial communities. To explore the enzyme-enhanced strategy of a continuous anaerobic dynamic membrane reactor (AnDMBR), the anaerobic codigestion system of food waste and corn straw was first operated stably, and then the best combination of compound enzymes (laccase, endo -β-1,4-glucanase, xylanase) was determined via a series of batch trials. The results showed that the methane yield (186.8 ± 19.9 mL/g VS) with enzyme addition was 12.2 % higher than that without enzyme addition. Furthermore, the removal rates of cellulose, hemicellulose and lignin increased by 31 %, 36 % and 78 %, respectively. In addition, dynamic membranes can form faster and more stably with enzyme addition. The addition of enzymes changed the structure of microbial communities while maintaining sufficient hydrolysis bacteria (Bacteroidetes), promoting the proliferation of Proteobacteria as a dominant strain and bringing stronger acetylation ability. In summary, the compound enzyme strengthening strategy successfully improved the methane production, dynamic membrane effect, and degradation rate of lignocellulose in AnDMBR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe 3 O 4 -bentonite enhances anaerobic digestion performance under severe acidification. • Fe 3 O 4 -bentonite boosts methane yield by 152% in acidified anaerobic digestion. • Bentonite enhances microbial diversity and richness in severely acidic environments. • Excessive non-conductive polysaccharides in EPS hinder Fe 3 O 4 ′s electron transfer. • The addition of Fe 3 O 4 -bentonite increases the possibility of DIET among microbes. Acidification recovery in anaerobic digestion of food waste is challenging. This study explored its in-situ recovery using a co-substrate of food waste and waste activated sludge. Fe 3 O 4 and bentonite were used as conductor and carrier, respectively, to enhance AD performance under severe acidification. The application of Fe 3 O 4 -bentonite resulted in a 152% increase in cumulative methane in the Fe 3 O 4 -bentonite 10 digester, demonstrating its effectiveness in restoring the acidified AD system. In acidified systems, bentonite enhanced the diversity and richness of microbial communities due to its buffering capacity. The excessive non-conductive polysaccharides excreted by bacteria in extracellular polymeric substances reduced the possibility of electron transfer by Fe 3 O 4. However, in the synergistic application of Fe 3 O 4 and bentonite, this resistance was alleviated, increasing the possibility of direct interspecies electron transfer, and accelerating the consumption of volatile fatty acids. This approach of integrating carrier and conductive materials is significant for in-situ restoration of acidified systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new type of co-pyrolysis biochar capable of adsorbing Cd (II) was prepared. • To tackle disposal of ADSR, treatment of OBDCA, and removal of Cd (II) concurrently. • The adsorption effect of biochar on Cd (II) is mainly mineral precipitation. • Adding OBDCA at over 500 °C enhances co-pyrolysis biochar's Cd (II) adsorption. Ionic cadmium (Cd (II)) in water is a significant threat to ecosystems, the environment, and human health. Research is currently focused on developing efficient adsorption materials to combat Cd (II) pollution in water. One promising solution involves co-pyrolyzing solid residue from anaerobic digestion of food waste with oil-based drill cuttings pyrolysis residue to create a biochar with high organic matter content. This biochar has a lower heavy metal content and leaching toxicity compared to China's national standards, making it both safe and resourceful. It exhibits a high adsorption capacity for Cd (II) in water, reaching up to 47.80 ± 0.37 mg/g. Raising the pyrolysis temperature above 600 °C and increasing the amount of pyrolysis residue beyond 30 % enhances the biochar's adsorption capacity. The adsorption process is primarily driven by mineral precipitation, offering a promising approach for dual waste resource management and reducing heavy metal pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • PLA/PBAT underwent modification through covalent bonding with enzymes. • The anaerobic co-digestion performance of the modified biodegradable plastic with food waste was assessed and examined. • The degradation of enzyme modified biodegradable plastic could increase from 5.21% to 29.70% compare to unmodified plastic. • The hydrolysis process was enhanced by the presence of highly active Bacteroidota and Thermotogota. A modified biodegradable plastic (PLA/PBAT) was developed by through covalent bonding with proteinase K, porcine pancreatic lipase, or amylase, and was then investigated in anaerobic co-digestion mixed with food waste. Fluorescence microscope validated that enzymes could remain stable in modified the plastic, even after co-digestion. The results of thermophilic anaerobic co-digestion showed that, degradation of the plastic modified with Proteinase K increased from 5.21 ± 0.63 % to 29.70 ± 1.86 % within 30 days compare to blank. Additionally, it was observed that the cumulative methane production increased from 240.9 ± 0.5 to 265.4 ± 1.8 mL/gVS, and the methane production cycle was shortened from 24 to 20 days. Interestingly, the kinetic model suggested that the modified the plastic promoted the overall hydrolysis progression of anaerobic co-digestion, possibly as a result of the enhanced activities of Bacteroidota and Thermotogota. In conclusion, under anaerobic co-digestion, the modified the plastic not only achieved effective degradation but also facilitated the co-digestion process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pumice and smectite are robust carriers for cell immobilization recycling. • Bacteria-pumice and bacteria-smectite nanocomposites are efficient for recycling. • Continuous production of microbial products from wastes was achieved. • Secondary treatment is unneeded in treating waste using the proposed nanocomposites. Recycling waste into commercial products is a profitable strategy but the lifetime of immobilized cells for long-term waste treatment remains a problem. This study presents alternative cell immobilization methods for valorizing food waste (FW) and oily food waste (OFW) to microbial carotenoids and proteins. Carriers (pumice or smectite), magnetite nanoparticles, and isolated photosynthetic bacteria were integrated to obtain magnetically recoverable bacteria-pumice and bacteria-smectite nanocomposites. After recycling five batches (50 d), chemical oxygen demand removal from FW reached 76% and 78% with the bacteria-pumice and bacteria-smectite nanocomposite treatments, respectively, and oil degradation in OFW reached 71% and 62%, respectively. Destructive changes did not occur, suggesting the durability of nanocomposites. The used nanocomposites had no impact on the lifespan of Moina macrocopa or water quality as assessed by toxicity analysis. Bacteria-pumice and bacteria-smectite nanocomposites are efficient for food waste recycling and do not require secondary treatment before being discharged into the environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • BC350 released orthophosphates via diffusion, while BC450 and BC550 via dissolution. • N, K, and DOC were released from biochar by a surface wash-off controlled process. • Nutrients released from BC450 and BC550 could stimulate the seed shoot length. • BC450 and BC550 exhibited a good potential as long-term slow-release N and P fertilizers. Food waste anaerobic digestion requires proper utilization of solid digestate, and pyrolysis emerges as an effective method to produce nutrient-rich biochar. This study investigated the leaching characteristics and speciation changes of nutrients in food waste digestate (FWD)-derived biochar pyrolyzed at 350 °C (BC350), 450 °C (BC450), and 550 °C (BC550). BC350 featured inorganic nitrogen, while BC450 and BC550 contained elevated organic nitrogen. Nitrogen, potassium, and dissolved organic carbon were released via a quick surface wash-off process. Polyphosphates prevailed in BC350 and leached through a fast diffusion-controlled process. BC450 and BC550 were dominated by Ca/Mg orthophosphates and released via a slow dissolution-controlled process. Leachates from BC450 and BC550 stimulated the shoot length of wheat seeds. After 5 leaching cycles, there were more aromatic dissolved organics, and BC450 and BC550 exhibited higher abundance of C-N and O-P-O. Overall, pyrolysis of FWD at 450 °C and 550 °C shows potential in producing slow-release biochar fertilizers for resource recycling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superphosphate (CP) and 'Mg(OH) 2 &H 3 PO 4 ′ increased NH 4 +-N by 75 % and 44 % respectively. • CP increased nitrogen ratio of humic acid to total by 49% compared to the control. • Phosphate additives improved the humification degree and the polymerization of humus. • Preserved NH 4 +-N due to phosphate additives was converted to nitrogenous humic acid. • Clustered bacterial positive relations in CP help to convert precursor to humic acid. This study aimed to compare the effect of different phosphate additives including superphosphate (CP) and MP [Mg(OH) 2 + H 3 PO 4 ] on nitrogen conversion, humus fractions formation and bacterial community in food waste compost. The results showed the ratio of humic acid nitrogen in total nitrogen (HA-N/TN) in CP increased by 49 %. Ammonium nitrogen accumulation was increased by 75 % (CP) and 44 % (MP). Spectroscopic techniques proved that phosphate addition facilitated the formation of complex structures in HA. CP enhanced the dominance of Saccharomonospora , while Thermobifida and Bacillus were improved in MP. Structural equation modeling and network analysis demonstrated that ammonium nitrogen can be converted to HA-N and has positive effects on bacterial composition, reducing sugars and amino acids, especially in CP with more clustered network and synergic bacterial interactions. Therefore, the addition of phosphate provides a new idea to regulate the retained nitrogen toward humification in composting. [ABSTRACT FROM AUTHOR]

[Display omitted] • LAFL was preferred as external carbon source on N removal in wastewater treatment. • Adding LAFL render a more robust structure of microbial community than using NaAc. • Functional species ascribe to heterotrophic nitrifiers/denitrifiers were enhanced. • Excess sludge production reduced by 109% with adding LAFL relative to adding NaAc. Lactic acid-rich fermentation liquid (LAFL) of food waste is found to act as a promising alternative carbon source for nitrogen removal in wastewater treatment. Here, LAFL was employed to investigate its impacts on nitrogen removal during raw municipal wastewater treatment with a comparison to sodium acetate (NaAc). Results indicated that nitrogen removals were comparable when incorporated with LAFL and NaAc (92.89 % v.s. 91.23 %). Unlike the utilization of NaAc, using LAFL could avoid suppressing the relative abundance of the nitrification genes and thus pose a negative risk to nitrogen removal during prolonged operation. The introduction of LAFL increased the stability and robustness of the functional microbial community and effectively reduced excess activated sludge (AS) generation by 109 % compared to NaAc addition, consequently enhancing nitrogen removal but diminishing the treatment cost. In general, LAFL exhibits prospective engineering application potentials and economic advantages in improving nitrogen removal by AS process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Conventional batch distillation is a reliable method for isolating ammonium bicarbonate. • 81 % of the ammonium bicarbonate in the food waste digestate liquor was recovered. • Ammonium bicarbonate content in food waste digestate liquor was reduced from 50 to 10 g/L. • Modification of the classical distillation still is required to conveniently harvest the crystals. • Granulation and coating are required for stabilization of the solid ammonium bicarbonate. Distillation is among the best techniques for management of ammoniacal nitrogen in anaerobic digestate; however, the suitability of the conventional system is neglected in favor of using more advanced setups. This investigation proves the reliability of the classical batch distillation apparatus for high throughput separation of solid crystals of ammonium bicarbonate from food waste digestate (FWD) liquor. Three replicates were carried out: 80 g of FWD liquor with a content of 50 g/L NH 4 HCO 3 was processed for 7.5 h under minimum heating power (<60 °C) and 200 rpm to avoid excessive foam formation. After performing the reactive distillation, 81 % of NH 4 HCO 3 was recovered as white solid crystals at the top of the distillation still. Although the distillation provided a solid material with the same structure and composition as those of the reagent-grade NH 4 HCO 3 , the stability of the isolated inorganic fertilizer was poorer, and it could lead to pollution swapping. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel biochar augmented enzymatic hydrolysis converted food waste to biofertilizers. • Composition of FW derived biofertilizers complied with Chinese national standards. • Quality of FW derived biofertilizers was field verified by leafy vegetable Pak Choi. • Application of FW derived biofertilizers didn't affect the soil chemical properties. • 361 kg CO 2 /1000 kg food waste could be eventually reduced with this novel approach. The present study developed a novel biochar-augmented enzymatic approach for fast conversion of food waste to solid and liquid biofertilizers. By augmented with 10 % of biochar and mediated with 5 % of food waste-derived hydrolytic enzymes mixture (i.e. fungal mash), 100 kg of food waste could be converted into 22.3 kg of solid biofertilizer with a water content of 30 % and 55.0 kg of liquid biofertilizer, which fulfilled Chinese national standards for solid and liquid organic biofertilizers, respectively. Field plantation results showed that the Pak Choi grown on food waste-derived biofertilizers was comparable with that on commercial ones, in terms of the vegetable productivity and nutrient contents. It was further revealed that the application of food waste-derived biofertilizers did not change soil chemical properties but enriched microbial diversity. This study clearly indicated that the biochar-augmented enzymatic approach for food waste conversion to biofertilizers was technically feasible and economically viable towards circular agriculture economy. [ABSTRACT FROM AUTHOR]

[Display omitted] • A two-stage PNA/D process was established for nitrogen removal of liquid digestate. • Ammonium oxidation was enhanced by coupling with ferric and sulfate reduction. • Anammox and denitrification accounted for 75% and 25% of N loss in PNA/D system. • EPS-mediated EET between sulfate/ferric reducers and aerobic ammonium oxidizers. Liquid digestate of food waste is an ammonium-, ferric- and sulfate-laden leachate produced during digestate dewatering, where the carbon source is insufficient for nitrogen removal. A two-stage partial nitrification-anammox/denitrification process was established for nitrogen removal of liquid digestate without pre-treatment (>300 d), through which nitrogen (95 %), biodegradable organics (100 %), sulfate (78 %) and iron (100 %) were efficiently removed. Additional ammonium conversion (20 %N) might be coupled with ferric and sulfate reduction, while produced nitrite could be further converted to di-nitrogen gas through anammox (75 %) and denitrification (25 %). Notably, since increasingly contribution of hydroxylamine producing nitrous oxide, and up-regulated expression of electron transfer and cytochrome c protein, the enhanced ammonium oxidation was probably conducted through extracellular polymeric substances-mediated electron transfer between sulfate/ferric-reducers and aerobic ammonium oxidizers. Thus, the established partial nitrification-anammox/denitrification process might be a cost-efficient nitrogen removal technology for liquid digestate, benefitting to domestic waste recycling and carbon neutralization. [ABSTRACT FROM AUTHOR]

[Display omitted] • YM1 inoculant improved the compost performance of high-salt and oily food waste. • YM1-inoculated compost exhibited a significant decrease in oil content. • YM1 inoculant significantly reduced the salt (Cl−) content in the compost. • Salt-tolerant beneficial microorganism was enriched in YM1 compost. • YM1 significantly altered the microbial community composition of food waste compost. To alleviate the inhibitory effects of salt and oil on food waste compost, the compost was inoculated with salt-tolerant and oil-degrading Bacillus safensis YM1. The YM1 inoculation could effectively improve compost maturation index. Compared with uninoculated group, the oil content and Cl− concentration in the 0.5% YM1-inoculated compost decreased significantly by 19.7% and 8.1%, respectively. The addition of the YM1 inoculant substantially altered the richness and composition of the microbial community during composting, as evidenced by the identification of 47 bacterial and 42 fungal biomarker taxa. The enrichment of some oil-degrading salt-tolerant microbes (Bacillus , Haloplasma , etc.) enhanced nutrient conversion, which is crucial for the improved maturity of the YM1 compost. This study demonstrated that YM1 could regulate both abiotic and biotic processes to improve high-salt and oily food waste composting, which may be an effective inoculant in the industrial-scale composting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different heating rates were tested in HTL of model compounds and real food waste. • Heating rate strongly affected HTL performances at lower residence times. • Heating rate influence at longer residence times was limited. • HTL performance was well described by the kinetic severity factor. Hydrothermal liquefaction (HTL) emerges as an efficient technology for converting food waste into biocrude. Among HTL parameters, the impact of heating rate is understudied. This study systematically explores its variation (5–115 K/min) on HTL performance using actual food waste and model compounds representing its constituents. Results revealed that an increase in heating rates significantly impacts HTL performances (+63 % biocrude and −34 % solid with food waste) with short residence times, as slower heating rates imply a longer overall time and a higher kinetic advancement of the reaction. Conversely, with longer residence times, the influence of heating rates becomes negligible, as kinetics during heating times are overshadowed by those at operating temperatures. A subtle effect of heating variation at extended residence time was observed only with carbohydrates. This research emphasizes the utility of a kinetic severity factor (KSF) as a valuable tool for simultaneously considering heating rates, operating times, and temperatures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluation of process integration for peach byproduct (PB) use in biorefinery. • PB has low lignin, high fermentable sugars (FS), free and bound phenolic compounds. • Drying at 50 °C reduced antioxidant capacity (AOC) and no of free phenolic compounds. • The bound phenolic compounds (>70 %) exerted larger AOC despite drying treatment. • Enzymatic saccharification slowed down by drying but gave ≈FS yield to control. This work assesses an integrated pathway for the revalorization of peach byproduct (PB) within a biorefinery. PB was subjected to an oven-drying (OD) treatment for its evaluation as a storage treatment. It was compared to freeze-drying and untreated material in terms of antioxidant capacity (AOC), phenolic compounds (PC) profile and fermentable sugar production. OD reduced the water content to less than 15 % while preserving the bound hydrolysable polyphenols, which were the more abundant PC (≈64 %) with the highest AOC. Drying treatments hampered polysaccharide accessibility, but some enzyme preparations released 60–70 g/L of fermentable sugars at relatively high solids loading (10 %). This study proposes a novel enzyme-based strategy for the valorisation of fermentable sugars and antioxidant compounds from PB. The sugars can be fermented into several building blocks while the solid residue enriched in recalcitrant phenolic compounds and proteins could be used to develop novel functional products for food/feed sectors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-pyrolysis of chicken feathers and macadamia nutshells doubles nitrogen retention; • Co-pyrolysis does not decrease porosity development; • Demineralization increased activated carbon's porosity significantly; • Co-pyrolysis coupled with demineralization leads to functional electrode materials. Global food waste emits substantial quantities of nitrogen to the environment (6.3 Mtons annually), chicken feather (CF) waste is a major contributor to this. Pyrolysis, in particular co-pyrolysis of nitrogen-rich and lignocellulosic waste streams is a promising strategy to improve the extent of pyrolytic nitrogen retention by incorporating nitrogen in its solid biochar structure. As such, this biochar can serve as a precursor for nitrogen-enriched activated carbons for application in supercapacitors. Therefore, this study investigates the co-pyrolysis of CF with macadamia nut shells (MNS) to create nitrogen-rich activated carbons. Co-pyrolysis increased nitrogen retention during pyrolysis from 9 % to 18 % compared to CF mono-pyrolysis, while the porosity was maintained. After removing undesirable inorganic impurities by dilute acid washing, this led to a specific capacitance of 21F/g using a scan rate of 20 mV/s. Finally, cycling stability tests demonstrated good stability with 73 % capacitance retention after 10 000 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Floating lipid-rich particles (LRP) phase was separated from food waste. • LRP is a potential flocculant for enhanced microalgae harvest efficiency (HE) • HE maximization showed 88.3%, with 91.6% floating biomat formation. • Results showed highest FAMEs yield of 11.17 g/L of total used volume using LRP. • Microalgae harvest by LRP enhanced lipid yield and biodiesel characteristics. Food waste was collected from the campus canteen and lipid-rich particles (LRP) phase was evaluated to harvest Tetradesmus obliquus. Box-Behnken design showed the highest harvest efficiency (HE) of 84.69 % in run#1 (LRP = 30 %; initial OD 680 = 1.75; and harvest time = 6 h). Numerical optimization ramps suggested 24.15 % (v/v) LRP ratio, initial OD 680 3.00, and harvest time 3.82 h for maximum HE. Two flocs were observed, a precipitate at the bottom (B-Floc) and a floating biomat (F-Floc). Experimental results showed HE of 88.3 %, with 67 % and 33 % of the harvested biomass forming F-Floc and B-Floc, respectively. Pre-heating of LRP in a boiling water bath for 10 min (HFB-T10) promoted F-Floc proportion up to 91.6 %. In addition, HFB-T10 showed the highest FAMEs yield of 11.17 g/L of the total used volume, which was significantly higher than that of the centrifuged cells and heat-untreated biomat. Moreover, HFB-T10 showed better iodine value and cetane number of the produced biodiesel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Food waste and effluent yield valuable oleochemicals and alcohol synthesis. • YL exhibits highest lipid production in synthetic carbon systems. • FAD2 and ADH expression are high in synthetic carbon than waste carbon source. • Both YL and PF produced high protein content during growth phase. • A biorefinery framework was established to synthesize the chemicals from food-waste. The research examined the capabilities of Yarrowia lipolytica (YL) and Pichia farinosa (PF) in converting sugars to ethanol and oleochemicals. Lipid, ethanol, protein yield and gene-expressions were analysed at different substrate concentrations (3 to 30 g/L) with glucose, food waste, and fermentation-effluent. Optimal results were obtained at 20 g/L using both synthetic carbon with 4.6 % of total lipid yield. Lauric and Caprylic acid dominance was noted in total lipid fractions. Protein accumulation (6 g/L) was observed in glucose system (20 g/L) indicating yeast strains potential as single-cell proteins (SCP). Fatty-acid desaturase (FAD12) and alcohol dehydrogenase (ADH) expressions were higher at optimum condition of YL (1.15 × 10−1, 3.8 × 10−2) and PF (5.8 × 10−2, 3.8 × 10−2) respectively. Maximum carbon reduction of 87 % depicted at best condition, aligning with metabolic yield. These findings highlights promising role of yeast as biorefinery biocatalyst. [ABSTRACT FROM AUTHOR]