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This work reported the effects of thermophilic bacterial agents on degrading persistent lignocellulose and reducing the loss of valuable nitrogen in kitchen waste (KW) composting. The results showed that thermophilic bacterial compound agents improved the high temperature period by 8 days, and increased the ligninase activity by 0.5-3 times during the composting process. The activity of cellulase increased up to 1 time in agent A (Geobacillus, Clostridium caenicola, Haloplasma) adding group by improving the microbial activity of lignocellulosic degradation metabolic pathways. Nitrogen storage increased to 70% in group added with agent B (Clostridium caenicola, Geobacillus, Clostridium sp. TG60-81) by increasing the population abundance of nitrogen-fixing microorganisms such as Bacillus, Hungateiclostridium and Herbaspirillum, and changed amino acid metabolic pathways. In general, agents A and B could increase the thermophilic phase, optimize the microbial community structure, realize the synergistic humification of carbon and nitrogen, and convert KW into mature and high quality fertilizers., Competing Interests: Declaration of competing interest The authors 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.)

The rising utilization of PLA/PBAT-ST20 presents potential ecological risks stemming from its casual disposal and incomplete degradation. To solve this problem, this study investigated the degradation capabilities of PLA/PBAT-ST20 by a co-culture system comprising two thermophilic bacteria, Pseudomonas G1 and Kocuria G2, selected and identified from the thermophilic phase of compost. Structural characterization results revealed that the strains colonized the PLA/PBAT-ST20's surface, causing holes and cracks, with an increase in the carbonyl index (CI) and polydispersity index (PDI), indicating oxidative degradation. Enzyme activity results demonstrated that the co-culture system significantly enhanced the secretion and activity of proteases and lipases, promoting the breakdown of ester bonds. LC-QTOF-MS results showed that various intermediate products were obtained after degradation, ultimately participating in the TCA cycle (ko00020), further completely mineralized. Additionally, after 15-day compost, the co-culture system achieved a degradation rate of 72.14 ± 2.1 wt% for PBAT/PLA-ST20 films, with a decrease in the abundance of plastic fragments of all sizes, demonstrating efficient degradation of PLA/PBAT-ST20 films. This study highlights the potential of thermophilic bacteria to address plastic pollution through biodegradation and emphasizes that the co-culture system could serve as an ideal solution for the remediation of PLA/PBAT plastics., Competing Interests: Declaration of Competing Interest The authors 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 B.V. All rights reserved.)

The mechanisms of biochar supported nano zero-valent iron (BC/nZVI) on two-phase anaerobic digestion of food waste were investigated. Results indicated that the performance of both acidogenic phase and methanogenic phase was effectively facilitated. BC/nZVI with the amount of 120 mg/L increased methane production by 32.21%. In addition, BC/nZVI facilitated direct interspecies electron transfer (DIET) between Geobacter and methanogens. Further analysis showed that BC/nZVI increased the abundance of most CAZymes in acidogenic phase. The study also found that BC/nZVI had positive effects on metabolic pathways and related functional genes. The abundances of acdA and ackA in acidogenic phase were increased by 151.75% and 36.26%, respectively, and the abundances of pilA and TorZ associated with DIET were also increased. Furthermore, BC/nZVI mainly removed IMP-12, CAU-1, cmeB, ErmR, MexW, ErmG, Bla2, vgaD, MuxA, and cpxA from this system, and reduced the antibiotic resistance genes for antibiotic inactivation resistance mechanisms., Competing Interests: Declaration of competing interest The authors 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.)

Biodegradable plastic bags (BPBs), meant for eco-friendly, often inadequately degrade in compost, leading to microplastic pollution. In this study, the effect of Fenton-like reaction with Fe 3 O 4 nanoparticles (NMs) on the plastisphere microorganisms' evolution and the BPBs' aging mechanism was revealed by co-composting of food waste with BPBs for 40 days. The establishment of the Fenton-like reaction was confirmed, with the addition of Fenton-like reagent treatments resulting in an increase of 57.67% and 37.75% in H 2 O 2 levels during the composting, compared to the control group. Moreover, the structural characterization reveals that increasing oxygen content continuously generates reactive free radicals on the surface, leading to the formation of oxidative cavities. This process results in random chain-breaking, significantly reducing molecular weights by 39.27% and 38.81%, thus showcasing a deep-seated transformation in the plastic's molecular structure. Furthermore, the microbial network suggested that the Fenton-like reaction enriched plastisphere keystone species, thus accelerating the BPBs' aging. Additionally, the Fenton-like reaction improved compost maturity and reduced greenhouse gas emissions. These results reveal the bio-chemical mechanisms of BPBs aging and random chain-breaking by the Fenton-like reaction, under alternating oxidative/anoxic conditions of composting and provide a new insight to resolve the BPBs' pollutions., Competing Interests: Declaration of Competing Interest The authors 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 B.V. All rights reserved.)

The effects of biodegradable plastics of different thicknesses (30 and 40 μm) and sizes (20 × 20, 2 × 2, and 1 × 1 mm) on anaerobic digestion of food waste and digestate phytotoxicity were investigated. Methane productions (38 days) for the groups with 20 × 20, 2 × 2, and 1 × 1 mm of 30 μm plastics were 92.46, 138.27, and 259.95 mL/gVS removal , respectively which are nearly 58 % higher than the control group (58.86 mL/gVS removal ). Methane production in 40 μm plastics groups was lower than in 30 μm groups of equal size. All sizes of 30 µm plastics promoted substrate hydrolysis, acidification, and relative abundance of key hydrolytic bacteria and methanogens. Phytotoxicity tests results showed that seed root elongation was inhibited in groups with 40 μm plastics. In conclusion, 30 μm biodegradable plastics were more suitable for anaerobic digestion with food waste than 40 μm., Competing Interests: Declaration of Competing Interest The authors 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 © 2023. Published by Elsevier Ltd.)

Halogenated benzoquinones (HBQs) could cause bladder cancer, but there were few related studies on the generation and control. In this study, the impact of different precursors, pH, bromide concentration, and algae-derived organic matters on the formation of HBQs and the removal efficiency by activated carbon were investigated. It was found that the chlorination of bisphenol A produced the most 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), reaching 14.86 µg/L at 1 hr, followed by tyrosine, 2-chlorophenol, P-hydroxybenzoic acid, trichlorophenol, and N-methylaniline. The production of 2,6-DCBQ increased first and then decreased from 0 to 36 hr (chlorination doses 0-20 mg/L), indicating that HBQs were unstable in water. Trihalomethanes (THMs) were detected during chlorination, and the concentration increased with prolongation of reaction time. 2,6-DCBQ production decreased and 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ) production increased with increment bromide concentration and the bromide promoted the formation of tribromomethane. The production of 2,6-DCBQ decreased with increase of pH, and the maximum production was 141.38 µg/L at pH of 5. Microcystis aeruginosa, Chlorella algae cells, and intracellular organic matters (IOM) could be chlorinated as potential precursors for HBQs. The most amount of 2,6-DCBQ was generated from algae cells of Microcystis aeruginosa, followed by Chlorella algae cells, Microcystis aeruginosa IOM, and Chlorella IOM. This study compared the removal efficiency of HBQs by granular activated carbon (GAC) and columnar activated carbon (CAC) under different carbon doses and initial concentrations of HBQs. It was found that the removal efficiency by GAC (80.1%) was higher than that by CAC (51.8%), indicating that GAC has better control for HBQs., Competing Interests: Declaration of Competing Interest The authors 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 © 2023. Published by Elsevier B.V.)

The black soldier fly (BSF) rearing technology has been a promising bioconversion method for food waste (FW) disposal. However, when used independently, it currently only achieves low efficiency and biomass transformation rates (BTR). This study screened and identified two strains of gut beneficial bacteria, Bacillus cereus and Bacterium YC-LK-LKJ45. The efficiency of a complex culture formulated by these strains was investigated, focusing on enhancing FW reduction and high-value biomass production during the rearing of BSF larvae. The coculture agent group (G1-10%, with two strains in 1:1 volume ratio at a 10 % dosage) exhibited higher larval yield (627.67 g·kg -1 ), BTR (47.90 %), FW reduction efficiency (80.67 %), and total protein and fat yield (261.99 g·kg -1 and 46.24 g·kg -1 ) compared to the control and the monoculture agent group (which added a single gut beneficial bacteria agent, either Bacillus cereus or Bacterium YC-LK-LKJ45). The bacterial agent altered the richness and diversity of the gut microbial community of BSF, increasing the relative abundance of beneficial bacteria such as Bacillus, Oceano bacillus, and Akkermansia, while decreasing pathogenic bacteria, such as Acinetobacter and Escherichia-Shigella. Structural equation model quantification revealed that α-diversity (λ = 0.897, p < 0.001) and BTR (λ = 0.747, p < 0.001) are crucial drivers for enhancing high-value biomass during bioaugmentation rearing. This investigation provides a theoretical framework for the effective management of food waste using BSF, enhancing its decomposition and transformation into higher-value biomass., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier B.V. All rights reserved.)

The objective of this research was to investigate the effect of bulking agents on the maturity and gaseous emissions of composting kitchen waste. The composing experiments were carried out by selected core bacterial agents and universal bacterial agents for 20 days. The results demonstrated that the addition of core microbial agents effectively controlled the emission of typical odor-producing compounds. The addition of core and universal bacterial agents drastically reduced NH 3 emissions by 94% and 74%, and decreased H 2 S emissions by 78% and 27%. The application of core microbial agents during composting elevated the peak temperature to 65 °C and in terms of efficient temperature evolution (>55 °C for 8 consecutive days). The organic matter degradation decreased by 65% from the initial values for core microbial agents were added, while for the other treatments the reduction was slight. Adding core microbial agents to kitchen waste produced mature compost with a higher germination index (GI) 112%, while other treatments did not fully mature and had a GI of <70%. Microbial analysis demonstrated that the core microbial agents in composting increased the relative abundances of Weissella , Ignatzschineria , and Bacteroides . Network and redundancy analysis (RDA) revealed that the core microbial agents enhanced the relationship between bacteria and the eight indicators ( p < 0.01), thereby improving the bio transformation of compounds during composting. Overall, these results suggest that the careful selection of appropriate inoculation microorganisms is crucial for improved biological transformation and nutrient content composting efficacy of kitchen waste.

The aim of this study was to assess the effect of polylactic acid (PLA) on microbial community composition and core metabolism pathways in food waste (FW) composting. The presence of PLA negatively influenced microbial community richness and decreased respectively the abundance of Bacillus, Halocella and Cellvibrio at mesophilic, thermophilic and mature phases. Analysis of microbial metabolism at the gene level help to understand the mechanism in co-composting with FW and PLA. The expression of core functional genes related to lactide metabolism was stimulated by PLA degradation at thermophilic and mature phases. The sum of absolute abundance of functional genes that involved in first and second carbon oxidation of tricarboxylic acid cycle was decreased due to the existence of PLA. The transformation between 2-Oxoglutarate and Succinyl-CoA were interfered in thermophilic phase, which might result in the lower germination index in PLA group (115%) than that in control (186%)., Competing Interests: Declaration of Competing Interest The authors 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 © 2023 Elsevier Ltd. All rights reserved.)

With the accelerated construction of biogas plants, the amount of biogas residues are expanding. Composting has been widely implemented to deal with biogas residues. Aeration regulation is the main factor affecting the post-composting treatment of biogas residues as high-quality fertilizer or soil amendment. Therefore, this study aimed to investigate the impact of different aeration regulations on full-scale biogas residues compost maturity by controlling oxygen concentration under micro-aeration and aeration conditions. Results showed that micro-aerobic extended the thermophilic stage of 17 days at above 55 ℃ and facilitated the mineralization process of organic nitrogen into nitrate nitrogen to retain higher N nutrition levels compared to aerobic treatment. For biogas residues with high moisture, aeration should be regulated at different full-scale composting stages. Total organic carbon (TOC), NH 4 + -N, NO 3 - -N, total potassium (TK), total phosphorus (TP) and the germination index (GI) could be used to evaluate stabilization, fertilizer efficiency and phytotoxicity of compost with frequent monitoring times. However, seedling growth trials were still necessary in full-scale composting plants when changing of composting process or biogas residues feedstock., Competing Interests: Declaration of Competing Interest The authors 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 © 2023 Elsevier Ltd. All rights reserved.)

The addition of carbonaceous materials into anaerobic digestion (AD) has gained widespread attention due to their significant effects on anaerobic performance and antibiotic resistance gene (ARG) removal. This study selected graphite, graphene, and graphene oxide (GO) as additives to investigate variations in AD performance, ARG removal, microbial community diversity and structure in wet AD systems. The results indicated that the addition of graphite-based materials in wet AD systems could increase degradation of solid organic matters by 0.91%-3.41% and utilization of soluble organic fractions by 10.43%-13.67%, but could not stimulate methane production. After the addition of graphite and graphene, ARG removal rates were effectively increased to 90.85% and 94.22%, respectively. However, the total ARG removal rate was reduced to 77.46% with the addition of GO. In addition, the microbial diversity in the wet AD process was enhanced with the addition of GO only, graphite and graphene led to a reduction in it. As for bacterial community, graphite and graphene increased the abundance of Thermotogae from 43.43% to 57.42% and 58.74%, while GO increased the abundance of Firmicute from 49.90% to 56.27%. For the archaeal community, the proportion of hydrogenotrophic methanogens was improved when adding each graphite-based material; however, only GO increased Methanosaeta that was acetoclastic methanogens. Finally, methanogens were found as the ARG host, and ARGs that belong to the same subtype might exist in the same host bacteria.

The promotion effects of biochar supported nano zero-valent iron (BC/nZVI) with different carbon/iron ratios on two-phase anaerobic digestion (AD) of food waste (FW) were studied. Results suggested that when the carbon/iron ratio was 3:1 AD system showed the best performance, with the concentration of volatile fatty acids (VFAs) in acidogenic phase (AP) and the cumulative methane production in methanogenic phase (MP) increased by 31.4% and 24.8%, respectively. Metagenomic analysis demonstrated that BC/nZVI increased the relative abundance of Defluviitoga in AP, and promoted the growth of Methanothrix in MP. Metabolic pathway analysis in AP indicated that BC/nZVI mainly promoted the abundances of acetate kinase and butyrate kinase to enhance acid production. Methane metabolism pathway analysis in MP revealed that BC/nZVI increased methane production by promoting the module of M00357 and activating related enzymes. The results of this sutdy showed that BC/nZVI promoted AD of FW mainly through acetoclastic methanogenic pathway., Competing Interests: Declaration of Competing Interest The authors 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 © 2023. Published by Elsevier Ltd.)

The problem of taste and odor (T&O) in drinking water is a widespread societal concern and highlights substantial challenges related to the detection and evaluation of odor in water. In this study, the portable electronic nose PEN3, which is equipped with ten different heated metal sensors, was applied to analyze its applicability, feasibility and application scenarios for the detection of typical odorants, such as 2-methylisobornel (2-MIB), geosmin (GSM), β-cyclocitral, β-ionone, and other T&O compounds in source water, while avoiding uncertainties and instability related to manual inspection. All the T&O compounds could be effectively differentiated by principal component analysis (PCA). Linear discriminant analysis (LDA) showed that the odors varied greatly between different samples and could be effectively distinguished. As the odorant concentration increased, the sensor response intensity of the primary identification sensors R6 and R8 increased with a significant positive correlation. For Microcystis aeruginosa, an algae that produces odorants, PCA could distinguish the odors of algae at a series of densities at different concentrations. The responses of R10 showed a significant increase with increasing algae density, implying the production of more aliphatic hydrocarbons and other odor compounds. The results indicated that the electronic nose could provide a promising alternative to traditional unstable and complex detection methods for the detection of odorous substances in surface water and early warning of odor events. This study aimed to provide technical support for rapid monitoring and early warning of odorants in source water management., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier Inc. All rights reserved.)

Biodegradable plastic bags (BPBs) to collect food waste and microplastics (MPs) produced from their biodegradation have received considerable scientific attention recently. Therefore, the current study was carried out to assess the co-composting efficiency of biodegradable plastic bags (polylactic acid (PLA) + polybutylene terephthalate (PBAT) + ST20 and PLA + PBAT+MD25) and food waste. The variations in greenhouse gas (GHG) emissions, microbial community and compost fertility were likewise assessed. Compared with the control, PLA + PBAT+ST20 and PLA + PBAT+MD25 both accelerated organic matter degradation and increased temperature. Moreover, PLA + PBAT+ST20 aggravated CH 4 and CO 2 emissions by 12.10 % and 11.01 %, respectively. PLA + PBAT+MD25 decreased CH 4 and CO 2 emissions by 5.50 % and 9.12 %, respectively. Meanwhile, compared with PLA + PBAT+ST20, the combined effect of plasticizer and inorganic additive in PLA + PBAT+MD25, reduced the NO 3 - -N contents, seed germination index (GI) and compost maturity. Furthermore, adding BPBs changed the richness and diversity of the bacterial community (Firmicutes, Proteobacteria and Bacteroidetes). Likewise, redundancy analysis (RDA) showed that the co-compost system of BPBs and food waste accelerated significantly bacterial community succession from Firmicutes and Bacteroidetes at the initial stage to Proteobacteria and Actinobacteria at the mature stage, increased co-compost temperature to over 64 °C and extended thermophilic composting phase, and promoted the degradation of MPs. Additionally, according to structural equation model quantification results, the inorganic additive of PLA + PBAT+MD25 had more serious toxicity to microorganisms and had significantly adverse effects on GI through CO 2 -C (λ = -0.415, p < 0.05) and NO 3 - -N (λ = -0.558, p < 0.001), thus reduced compost fertility and quality. The results also indicated that the BPBs with ST20 as an additive could be more suitable for industrial composting than the BPBs with MD25 as an additive. This study provided a vital basis for understanding the potential environmental and human health risks of the MPs' generated by the degradation of BPBs in compost., Competing Interests: Declaration of competing interest The authors 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 © 2023. Published by Elsevier B.V.)

Waste activated sludge has been frequently used as mixed substrate to produce polyhydroxyalkanoate (PHA). However, insufficient research on microbial metabolism has led to difficulties in regulating PHA accumulation in mixed microbial cultures (MMCs). To explore the variation of functional genes during domestication and the effect of different pH conditions on metabolic pathways during PHA accumulation, MMCs were domesticated by adding acetate and propionate with aerobic dynamic feeding strategy for 60 days. As the domestication progressed, the microbial community diversity declined and PHA-producing bacteria, Brevundimonas, Dechloromonas and Hyphomonas, were enriched. Through bacterial function prediction by PICRUSt the gene rpoE involved in starvation resistance of bacteria was enriched after the domestication. The pH value of 8.5 was the best condition for PHA accumulation in MMCs, under which a maximum PHA content reached 23.50% and hydroxybutyric (HB)/hydroxyvaleric (HV) reached 2.22. Untargeted metabolomics analysis exhibited that pH conditions of 7 and 8.5 could promote the up-regulation of significant differential metabolites, while higher alkaline conditions caused the inhibition of metabolic activity. Functional annotation showed that pH condition of 8.5 significantly affected Pyrimidine metabolism, resulting in an increase in PHA production. Regarding the pathways of PHA biosynthesis, acetoacetate was found to be significant in the metabolism of hydroxybutyric, and the alkaline condition could restrain the conversion from hydroxybutyric (HB) to the acetoacetate to protect PHB accumulation in MMCs compared with neutral condition. Taken together, the present results can advance the fundamental understanding of metabolic function in PHA accumulation under different pH conditions., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier Ltd. All rights reserved.)

With the booming development of biogas industry to treat organic waste in China, the by-product of biogas slurry was accompanied with a huge amount. Static storage process of biogas slurry was normally operated under different seasons before application to land which would cause nutrition decomposition and greenhouse gas emission. Thus, the aim of this study was to investigate the nutrition decomposition, greenhouse gas emission (CH 4 and N 2 O), and phytotoxicity of biogas slurry under different static temperatures, furthermore to illuminate the network among them and functional microorganism. According to the results, higher temperature at 30 °C contributed to fast and complete degradation of COD. In addition, more quantity of NH 4 + conversion and NO 3 - formation appeared at 30 °C. These factors resulted in relatively less crop toxicity together. CH 4 was the dominant greenhouse gas emission than N 2 O and was highest in 30 °C treatment with total emission of 273.7 L/(m 3 ·d) and greenhouse gas emission of 20.01 kg CO 2 e (carbon dioxide equivalent). Lower temperature was conductive to N reservation and reduction of greenhouse gas emission, but making against with stabilization of organic matter and crop safety. At the same dilution times (≤3) of biogas slurry with deionized water, higher temperature at 30 °C could reduce 30 days of storage time, but 10 °C was still unsafe for crop. Structural equation model was further illustrated the positive effect of temperature on NO 3 - , CH 4 , GI, and N 2 O and negative on COD and NH 4 + . These results could help to monitor the environmental risk, evaluate the maturity, guide the irrigation scheme, and regulate the static storage condition of biogas slurry under different seasons., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In the present study, a biochemical strategy for improving propionic acid production from kitchen waste acidification by bioaugmentation with Propionibacterium acidipropionici (P. acidipropionici) was investigated. When the inoculum of P. acidipropionici was 30% (w/w) of the seeding sludge, the propionic acid production increased by 79.57%. Further, bioaugmentation improved the relative abundance of Firmicute and Actinobacteria. The results of metagenomic analysis further reveal that the ATP-binding cassette (ABC) transporters and all related pathways of Propanoate metabolism (ko00640) were enriched when P. acidipropionici was added. For Propanoate metabolism, most functional genes involved in the conversion from Glycolysis / Gluconeogenesis (ko00010) to Propanoyl-CoA and conversion from Propanoyl-CoA to propionic acid were enhanced after bioaugmentation with P. acidipropionici, thereby promoting propionic acid production. As such, bioaugmentation with P. acidipropionici was effective in the anaerobic acidification of kitchen waste for propionic acid production., Competing Interests: Declaration of Competing Interest The authors 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 © 2022 Elsevier Ltd. All rights reserved.)

Food waste, as a major part of municipal solid waste, has been increasingly generated worldwide. Efficient and feasible utilization of this waste material for biomanufacturing is crucial to improving economic and environmental sustainability. In the present study, black soldier flies (BSF) larvae were used as carriers to treat and upcycle food waste. Larvae of the BSF were incubated with UV light for 10, 20, and 30 min at a wavelength of 257.3 nm and an intensity of 8 W. The food waste utilization efficiency, antioxidant assays, antibacterial activity, and bioactive metabolites without and with UV treatment were determined and compared. Results showed that the BSF larvae feed utilization rate was around 75.6%, 77.7%, and 71.2% after UV treatment for 10, 20, and 30 min respectively, contrasting with the non-UV induced group (73.7%). In addition, it was perceived that the UV exposure enhanced antioxidant and antimicrobial properties of BSF extracts, and the maximum values were observed after 20 min UV induction time. Moreover, UV-induced BSF extracts showed an improved metabolic profile than the control group, with a change in the amino acids, peptides, organic acids, lipids, organic oxides, and other derivatives. This change in metabolomics profile boosted environmental signaling, degradation of starch, amino acids, sugars, and peptide metabolism. It was concluded that the bioconversion of food wastes using UV-induced BSF larvae can enhance the generation of a variety of functional proteins and bioactive compounds with potent antioxidant and antimicrobial activity. However, more studies are required to exploit the efficiency of UV treatment in improving BSF's potential for upcycling of food wastes.

A large amount of food waste (FW) brings environmental pollution and sanitation problems. Anaerobic digestion (AD) is an effective technology to treat FW and generate biogas energy. This study investigated the effect of biochar supported nano zero-valent iron (BC-nZVI) on AD performance of FW. Results showed that the cumulative methane yield (CMY) increased by 21.52%-54.90% and the lag time decreased significantly with BC-nZVI. Under mesophilic and thermophilic condition, the peak of CMY was achieved at 178.82 ± 5.27 mL/g VS and 193.01 ± 6.81 mL/g VS with 5 g/L BC-nZVI, respectively. Besides, BC-nZVI stimulated hydrolysis process and reduced the inhibition of NH 4 + -N and volatile fatty acids accumulation, and it could improve the system stability. Structural equation model analysis indicated that digestion time, BC-nZVI, NH 4 + -N, temperature and total volatile fatty acid had significant effects on CMY, explaining 92.20% of its total variation. The metagenomic analysis of key microorganisms and related metabolism pathways involved in AD system was further investigated. The results suggested that BC-nZVI contributed to strengthen methanogenesis through enriching the various predominant methanogenic pathways and activating most enzymes related to methane metabolism. BC-nZVI could improve the AD system function and provided a better AD performance by shifting the microbial communities and altering functional genes. This study provided a theoretical basis for BC-nZVI applications and improvements in AD process of FW., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

Biogas slurry(BS) from food waste anaerobic fermentation coexisted a lot of salinity that could damage soil and crops health. So, this study was to explore the effect of the application of biogas slurry on soil salinization in 1 ∼ 4 cm, 4-6 cm and 6 ∼ 8 cm soil layers every 10 days, Chinese cabbage growth and rhizobacteria. The results indicated that ≤ 10% concentration of biogas slurry was uninjurious for soil and plant, the dry weight growth rate was 73.7% compared with CK, long term application should be further evaluated the potential risk of salinity on underground water and human health. As for high concentration of biogas slurry ≥ 10% concentration of biogas slurry could inhibit the seed germination and root elongation, and the germination percentage was declined from 87.6% to 2.4%, but 50% and 100% concentration of biogas slurry showed a promotion of crop growth because of sufficient nutrition. However, the potential accumulation of salinity could be seen in high concentration of biogas slurry for long term application especially in top1-4 cm soil. Correlation analysis showed that Cl - was the main factor resulting high EC in all soil layers. 16S rRNA sequencing showed that UCG-004, Ketobacter, Sphingopyxis and RB41 could be regard as the indicators for determining the potential jeopardize on soil environmental by high salinity from biogas slurry., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The rapid development of biogas plants in China has generated large quantities of digestate. The disparity between the continuity of biogas plant operation and the seasonality of digestate utilization has led to the need to store digestate. Therefore, untargeted profiling of bioactive compounds in the digestate stored under aerobic and anaerobic conditions was performed. The antioxidant and antifungal activity of digestate stored under varying conditions was likewise assessed. The results delineated that digestate storage under varying conditions brought about the degradation of organic acids, alkenes, aldehydes, alcohols, ketones, ethers, amino acids and their derivatives, and esters, leading to the stabilization of digestate components. Together, these new data revealed that digestate storage for up to 20 days under aerobic conditions promotes glycine, serine, and threonine degradation pathways and enhances biotin and vitamins production. In contrast, anaerobic storage enhances the taurine and hypotaurine metabolic pathways and increases the derivation of antimicrobial substances, such as indole alkaloids. Moreover, digestate storage under anaerobic conditions promotes antioxidant and antifungal activity more than storage under aerobic conditions. These findings can contribute to the future development of high-value agricultural products from digestate and the sustainability of biogas plants. Further studies are required for the untargeted metabolomic of digestate under storage to explore the underlying mechanisms of promoting disease resistance by the digestate upon land application.

The fate of antibiotic resistance genes (ARGs) in full-scale anaerobic digestion (AD) of food waste (FW) and in the soil applied with biogas slurry has not been fully understood. In this study, 12 targeted ARGs and intI1 in FW, intermediate product, and biogas slurry from three full-scale AD were analyzed. The results showed that subcritical water pretreatment was an effective method for ARG attenuation, by which the absolute abundance of total targeted ARGs was removed by 99.69%. The predominant ARGs (ermB, tetM, and tetW) in FW were removed more than 99% after subcritical water pretreatment. The result of field experiments with biogas slurry as fertilizer showed that the absolute abundance of several ARGs (sul2, tetM, blaOXA-1, blaTEM) and intI1 accumulated significantly compared to the control group (CK) during three consecutive growth stages of the rice. The detected abundance of ARGs in paddy field soil increased from 190.50 (CK) to 8.87 × 10 4 copies/g (wet weight) (soil) during tillering stage, and increased from 4102.65 (CK) to 4.38 × 10 4 copies/g (wet weight) (soil) during heading time. Biogas slurry improved the soil nutrients (TN, AN, TP, and AP); meanwhile, the concentrations of total salt and Cl - increased. Network analysis indicated that 28 genera were the possible hosts of ARGs; variation partitioning analysis (VPA) indicated that microbial communities (contribution 59.30%) were the main factors that affected the fate of ARGs and intI1., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Ozone has been widely applied during drinking water treatment for organic pollutants removal, however, the ozonation by-products such as bromate, aldehydes, and carboxylic acids could be produced. To investigate the ozonation by-products formation and control efficiency, a continuous pilot-scale system was established including conventional treatment and ozone-biological activated carbon (O 3 -BAC) treatment processes in a waterworks that receives bromide-bearing source water from the Yellow River in northern China. It was found that ozonation could reduce the threshold odour number and the haloacetic acids formation potential effectively. As 1.8-2.6 mg/L of ozone was applied, the bromate concentration would exceed the standard of 10 μg/L. Simultaneously, ozonation led to a large number of formaldehyde, methylglyoxal and other aldehydes. At the ozone dosage of 3.0 mg/L, the total concentration of aldehydes reached the highest of 45.4 μg/L. Ammonia and hydrogen peroxide (H 2 O 2 ) addition could inhibit the formation of bromate effectively. The application of H 2 O 2 induced an increase in aldehydes concentration reaching a maximum concentration of 57.6 μg/L. During the BAC treatment, the removal rate of aldehydes would reach 19%-41%. The addition of H 2 O 2 inhibited the formation of bromate but increased the production of aldehydes, thus it is important to search a balance point for controlling bromate and aldehydes simultaneously. The H 2 O 2 /O 3 (g/g) of 1.0 could be possible to control both bromate and aldehydes concentrations within the standards., Competing Interests: Declaration of competing interest The authors 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 © 2021 Elsevier B.V. All rights reserved.)

Food waste is becoming more prevalent, and managing it is one of the most important issues in terms of food safety. In this study, functional proteins and bioactive peptides produced from the enzymatic digestion of black soldier fly (Hermetia illucens L., BSF) fed with food wastes were characterized and quantified using proteomics-based analysis. The results revealed approximately 78 peptides and 57 proteins, including 40S ribosomal protein S4, 60S ribosomal protein L8, ATP synthase subunit alpha, ribosomal protein S3, Histone H2A, NADP-glutamate dehydrogenase, Fumarate hydratase, RNA helicase, Chitin binding Peritrophin-A, Lectin C-type protein, etc. were found in BSF. Furthermore, functional analysis of the proteins revealed that the 60S ribosomal protein L5 (RpL5) in BSF interacted with a variety of ribosomal proteins and played a key role in the glycolytic process (AT14039p). Higher antioxidant activity was found in peptide sequences such as GYGFGGGAGCLSMDTGAHLNR, VVPSANRAMVGIVAGGGRIDKPILK, AGLQFPVGR, GFKDQIQDVFK, and GFKDQIQDVFK. It was concluded that the bioconversion of food wastes by BSF brought about the generation of a variety of functional proteins and bioactive peptides with strong antioxidant activity. However, more studies are required to exploit BSF's potential in the value addition of food wastes., (© 2022. The Author(s).)

Ozone is widely applied for disinfection in drinking water treatment and the disinfection by-product bromate would be produced during the ozonation of bromide-bearing water. Hydrogen peroxide (H 2 O 2 ) addition could effectively control the formation of bromate. However, the bromate depression performance would be impacted by water qualities. In this study, typical source water containing bromide in eastern China was selected to investigate bromate depression effect under different organic matter, ammonia and bromide concentrations during the H 2 O 2 -O 3 process. The results display that organic matter, ammonia and bromide concentration could influence the formation of bromate significantly. As tyrosine was applied to increase the dissolved organic carbon (DOC) concentration of source water by 2.0 and 3.0 mg/L, the total concentration of bromate produced decreased gradually as the H 2 O 2 /O 3 (g/g) doses increased from 0 to 1.0 and bromate concentration could be controlled below 10 μg/L as H 2 O 2 /O 3 (g/g) was 0.5 and 1.0. As ammonia concentration increased by 0.1 and 0.5 mg/L, lower H 2 O 2 /O 3 (g/g) doses would lead to an increase in bromate generation. As more H 2 O 2 was added in water, the bromate formation would be suppressed. The increase of bromide concentration induced higher bromate formation. When the bromide concentration increased by 50 and 200 μg/L, bromate concentration was 10.7 μg/L and 41.2 μg/L respectively at the H 2 O 2 /O 3 (g/g) of 1.0, higher than the standard level. As 200 μg/L of bromide was added to the water, bromate concentration increased significantly and then decreased as H 2 O 2 /O 3 (g/g) increased and more H 2 O 2 would be needed for bromate control., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study explored and compared the influence of graphite, graphene, and graphene oxide (GO) on the performance of anaerobic co-digestion fed with sewage sludge and food waste, the variations of antibiotic resistance genes (ARGs), and the evolution of microbial community. Graphene exhibited the best performance for improving methane production and organic degradation, which increased by 36.09% and 23.07% compared with control group. The experimental results showed that graphene had the greatest influence on the removal efficiency of blaOXA-1, macrolide resistance genes (ermF and ermB), and some tetracycline resistance genes (tetQ and tetX); however, the removal efficiency of sulfonamide resistance genes (sul1 and sul2), intI1, and some tetracycline resistance genes (tetM, tetO, and tetW) were highest when GO was added. Network analysis indicated that the host cells of mefA, ermB, and tetO were different from other ARG host cells; moreover, graphene controlled the horizontal transfer of ARGs between microbial communities., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Anaerobic digestion (AD) processes of food waste (FW) have potential risk on environments due to the prevalence and dissemination of antibiotic resistance genes (ARGs). This study investigated the effect of bentonite on methane production and the abundance of ARGs in biogas slurry and residue during AD of FW. Results showed that methane production increased by 68.52% and 56.79% with 3 g/L and 5 g/L of bentonite in mesophilic and thermophilic digestion, respectively. Adding 5 g/L of bentonite effectively reduced the genes of ermB, ermF, tetQ, tetX, sul1, sul2 and intI1 with a range of 80.82% - 100.00% in biogas residue under mesophilic reactor. The abundance of ARGs and intI1 in biogas residue were lower than in slurry under both temperatures with 5 g/L of bentonite. Statistical analysis indicated that bentonite and temperature were main driver factors which could impact ARGs by influencing the abundance and structure of microbial communities., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The intrinsic reason determining digestion performance of 100-160 °C preheated food waste after recovering floatable oil (FO-recovered FW) was investigated using two-dimensional correlated infrared spectroscopy, three-dimensional fluorescence spectroscopy and high-throughput 16S rRNA amplicon sequencing. The results indicated that thermal temperature significantly affected CH 4 production of FO-recovered FW due to different structural alteration degree of starch, protein, cellulose and lipid components. Fragmentation of starch mainly occurred at 100 °C. The hydrolytic and acidogenic rate of starch was promoted and accordingly induced rapid growth of carbohydrate-fermenting bacteria, which resulted in severe acidification. Protein hydrolysis and cellulose H-bonds cleavage occurring at 120-160 °C accelerated the accessible sites interacting with microbial hydrolytic enzymes, and growth of Cloacimonetes and Syntrophomonas enhanced CH 4 production. Non-degradable humic acid-like organics remarkably formed at 160 °C caused a carbon loss and digestion inhibiting/deteriorating. Pretreatment at 120 °C was feasible for promoted methane production based on energy assessment., (Copyright © 2019. Published by Elsevier Ltd.)

The effects of nanoscale zero-valent iron (nZVI) on the performance of food waste anaerobic digestion and the fate of antibiotic resistance genes (ARGs) were investigated in thermophilic (TR) and mesophilic (MR) reactors. Results showed that nZVI enhanced biogas production and facilitated ARGs reduction. The maximum CH 4 production was 212.00 ± 4.77 ml/gVS with 5 g/L of nZVI in MR. The highest ARGs removal ratio was 86.64 ± 0.72% obtained in TR at nZVI of 2 g/L. nZVI corrosion products and their contribution on AD performance were analyzed. The abundance of tetracycline genes reduced significantly in nZVI amended digesters. Firmicutes, Chloroflexi, Proteobacteria and Spirochaetes showed significant positive correlations with various ARGs (p < 0.05) in MR and TR. Redundancy analysis indicated that microbial community was the main factor that influenced the fate of ARGs. nZVI changed microbial communities, with decreasing the abundance bacteria belonging to Firmicutes and resulting in the reduction of ARGs., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Food waste (FW) is rich in starch, fat, protein and cellulose. It is easy to decay and brings environmental pollution and other social problems. FW shows a high potential to produce methane by anaerobic digestion (AD) due to its high organic content. However, many inhibitors, such as accumulation of ammonia and volatile fatty acids (VFAs), usually result in inefficient performances and even process failure. Microorganisms play an important role in the process of hydrolysis, acidogenesis, acetogenesis and methanogenesis. This review provided a critical summary of microbial characteristics to obtain connects of microbial community structure with operational conditions at various states of AD, such as mesophilic and thermophilic, wet and dry, success and failure, pretreated or not, lab-scale and full-scale. This article emphasizes that it is necessary to analyze changes and mechanisms of microbial communities in unbalanced system and seek efficiency dynamic succession rules of the dominant microorganisms., (Copyright © 2017. Published by Elsevier Ltd.)

Odorous gas emission characteristic along with the successive processes of a typical full-scale food waste (FW) anaerobic digestion plant in China was investigated in September and January. Seasonal variations in pollutant concentration and principal component analysis (PCA) showed markedly different characteristics between the two months. However, the main reason for the seasonal difference at the sorting process differed from the reason for the seasonal difference at other treatment units. Most odorous volatile organic compound (VOC) concentrations tested near an anaerobic digestion tank were similar and low in both months. Odor indices, including odor contribution (OC) and odor activity value (OAV) of various odorants, were further calculated to evaluate the malodor degree and contribution to the nuisance smell of any odorant. Brought about by people's different dietary habits, H2S and sulfocompounds were found to be dominant contributors to the large total OVA in the January test. By contrast, oxygenated organic compounds played an important role on the sum of OVA in September.

Food waste treatment plants (FWTPs) are usually associated with odorous nuisance and health risks, which are partially caused by volatile organic compound (VOC) emissions. This study investigated the VOC emissions from a selected full-scale FWTP in China. The feedstock used in this plant was mainly collected from local restaurants. For a year, the FWTP was closely monitored on specific days in each season. Four major indoor treatment units of the plant, including the storage room, sorting/crushing room, hydrothermal hydrolysis unit, and aerobic fermentation unit, were chosen as the monitoring locations. The highest mean concentration of total VOC emissions was observed in the aerobic fermentation unit at 21,748.2-31,283.3 μg/m3, followed by the hydrothermal hydrolysis unit at 10,798.1-23,144.4 μg/m3. The detected VOC families included biogenic compounds (oxygenated compounds, hydrocarbons, terpenes, and organosulfur compounds) and abiogenic compounds (aromatic hydrocarbons and halocarbons). Oxygenated compounds, particularly alcohols, were the most abundant compounds in all samples. With the use of odor index analysis and principal components analysis, the hydrothermal hydrolysis and aerobic fermentation units were clearly distinguished from the pre-treatment units, as characterized by their higher contributions to odorous nuisance. Methanthiol was the dominant odorant in the hydrothermal hydrolysis unit, whereas aldehyde was the dominant odorant in the aerobic fermentation unit. Terpenes, specifically limonene, had the highest level of propylene equivalent concentration during the monitoring periods. This concentration can contribute to the increase in the atmospheric reactivity and ozone formation potential in the surrounding air., (Copyright © 2015. Published by Elsevier B.V.)