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Photocatalytic hydrogen evolution via water splitting was considered as a promising way of solar energy conversion and storage in the past decades. However, the weak visible-light response and fast recombination of electron-hole pairs are still main obstacles to overcome. Herein, a novel 2D/2D Bi 4 O 5 Br 2 /TL-Ti 3 C 2 (Thin layer-Ti 3 C 2) visible-light photocatalyst was successfully prepared by in-situ synthesis of Bi 4 O 5 Br 2 nanosheets on the surface of TL-Ti 3 C 2 at room temperature. The resulting Bi 4 O 5 Br 2 /TL-Ti 3 C 2 exhibits a higher hydrogen evolution activity (83.5 ​μmol·g−1·h−1) than that of pristine Bi 4 O 5 Br 2 (44.9 ​μmol·g−1·h−1) under visible-light irradiation. The enhanced hydrogen evolution activity of as-prepared photocatalyst mainly attributes to the increased visible light responsiveness and rapid transfer of photo-induced electrons. The strong interaction between TL-Ti 3 C 2 and Bi3+ in Bi 4 O 5 Br 2 nanosheets establishes a good electron transfer channel and close contact, which accelerates the transfer of photo-induced electrons from Bi 4 O 5 Br 2 to Ti 3 C 2 and promotes the separation of photo-generated charge carriers, thereby increasing the number of effective photo-induced electrons involved in the hydrogen evolution. This work provides a new insight into the construction of Bi x O y Br z /MXene photocatalyst system, and demonstrated that Ti 3 C 2 has excellent application potential in promoting the photocatalytic performance of bismuth-rich bismuth oxyhalides (Bi x O y X z X ​= ​Cl, Br, I). Benefiting from the rapidly transfers photo-induced electrons and increases the visible light responsiveness, the resulting 2D Bi 4 O 5 Br 2 /2D TL-Ti 3 C 2 manifests more significant photocatalytic hydrogen evolution activity (83.5 ​μmol·g−1·h−1) than that of pristine Bi 4 O 5 Br 2 (44.9 ​μmol·g−1·h−1). This work provides a new insight into the construction of Bi x O y Br z /MXene photocatalyst system, and demonstrated that Ti 3 C 2 has excellent application potential in promoting the photocatalytic performance of bismuth-rich bismuth oxyhalides (Bi x O y X z X ​= ​Cl, Br, I). Image 1 • Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2 was prepared by in-situ synthesis at room temperature. • Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2 manifests better photocatalytic H 2 evolution than Bi 4 O 5 Br 2. • The enhanced activity was mainly attributed to the rapidly charge transfer. • An electron transfer channel was established in Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2. • The possible H 2 evolution mechanism of Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2 was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • An idea and method of screening high selectivity and high activity electrocatalysts by machine learning was proposed. • The potential relationship between the physical properties of single-atom catalysts and their adsorption and catalytic properties was found. • Zn@ Pc -N 3 C 1 , Au@Pd-N 4 , Au@Pd-N 1 C 3 and Au@Py-N 3 C 1 were identified as electrocatalysts with high selectivity and activity for 2e- oxygen reduction reaction to prepare H 2 O 2. • The unique advantages of single-atom catalysts as the electrocatalyst for 2e- oxygen reduction reaction to prepare H 2 O 2 were explained and proved. Electrocatalysis has emerged as one of the most promising alternatives to conventional anthraquinone for preparing hydrogen peroxide (H 2 O 2) with high energy consumption and pollution because of its simplicity, convenience, and environmental friendliness. However, the oxygen reduction reaction (ORR) generating H 2 O 2 via the 2e- path is a competitive path for 4e–ORR to generate H 2 O. Therefore, it is crucial to identify an electrocatalyst with high selectivity and activity of 2e-ORR. Here, we established five machine learning (ML) models based on the adsorption free energy of O* (△G (O*)) of 149 single-atom catalysts (SACs) collected and the limiting potential (U L) of 31 SACs calculated using density functional theory (DFT) from the literature. We then obtained descriptors that could accurately describe SACs. Furthermore, 690 unknown SACs' 2e-ORR catalytic performance was well predicted. Four 2e-ORR materials with high selectivity and activity were screened: Zn@ Pc -N 3 C 1 , Au@Pd-N 4 , Au@Pd-N 1 C 3 , and Au@Py-N 3 C 1. We verified the U L of these SACs through DFT calculation, which was higher than the standard value, proving the ML model's validity. The ML-based method to predict the material properties with highly selective and active electrocatalysts provides an efficient, rapid, and low-cost method for discovering and designing more valuable SACs catalysts. [ABSTRACT FROM AUTHOR]

Persulfate oxidation (PS) is widely employed as a promising alternative for waste activated sludge pretreatment due to the capability of generating free radicals. The product differences and microbiological mechanisms by which PS activation triggers WAS digestion through multiple modes need to be further investigated. This study comprehensively investigated the effects of persulfate oxidation activated through multiple modes, i.e., ferrous, zero-valent iron (ZVI), ultraviolet (UV) and heat, on the performance of sludge digestion. Results showed that PS_ZVI significantly accelerated the methane production rate to 12.02 mL/g VSS. By contrast, PS_Heat promoted the sludge acidification and gained the maximum short-chain fatty acids (SCFAs) yield (277.11 ± 7.81 mg COD/g VSS), which was 3.41-fold compared to that in PS_ZVI. Moreover, ferrous and ZVI activated PS achieved the oriented conversion of acetate, the proportions of which took 73% and 78%, respectively. MiSeq sequencing results revealed that PS_Heat and PS_UV evidently enriched anaerobic fermentation bacteria (AFB) (i.e., Macellibacteroides and Clostridium XlVa). However, PS_Ferrous and PS_ZVI facilitated the enrichment of Woesearchaeota and methanogens. Furthermore, molecular ecological network and mantel test revealed the intrinsic interactions among the multiple functional microbes and environmental variables. The homo-acetogens and sulfate-reducing bacterial had potential cooperative and symbiotic relationships with AFB, while the nitrate-reducing bacteria displayed distinguishing ecological niches. Suitable activation modes for PS pretreatments resulted in an upregulation of genes expression responsible for digestion. This study established a scientific foundation for the application of sulfate radical-based oxidation on energy or high value-added chemicals recovery from waste residues. [Display omitted] • Effect of multiple activated persulfate oxidation on sludge digestion was studied. • Heat and UV activated persulfate effectively promoted the accumulation of SCFAs. • ZVI and Ferrous activated persulfate were beneficial for methane production. • Microbial community structures were altered by multiple persulfate activation modes. • Suitable activation modes for persulfate upregulated the critical genes expression. [ABSTRACT FROM AUTHOR]

Electro-fermentation (EF) has been extensively studied for recovering hydrogen and phosphorus from waste activated sludge (WAS), while was limited for the further application due to the low hydrogen yield and phosphorus recovery efficiency. This study proposed an efficient strategy for hydrogen and vivianite recovery from the simulated sludge fermentation liquid by sacrificial iron anode in EF. The optimum hydrogen productivity and the utilization efficiency of short chain fatty acids (SCFAs) reached 45.2 mmol/g COD and 77.6% at 5 d in pH 8. Phosphate removal efficiency achieved at 90.8% at 2 d and the high crystallinity and weight percentage of vivianite (84.8%) was obtained. The functional microbes, i.e., anaerobic fermentative bacteria, electrochemical active bacteria, homo-acetogens and iron-reducing bacteria were highly enriched and the inherent interaction between the microbial consortia and environmental variables was thoroughly explored. This work may provide a theoretical basis for energy/resource recovery from WAS in the further implementation. [Display omitted] • Enhanced hydrogen and vivianite recovery were realized in pH 8 via Fe mediated EF. • Appropriate iron release led to the higher crystallinity of vivianite in pH 8 group. • EAB, AFB and homo-acetogens preferred to enrich in pH 8 than other pH conditions. • The mutual symbiosis of microbes and environmental factors was the main mechanism in EF. [ABSTRACT FROM AUTHOR]

Microaerobic sludge bed systems could align with low-energy, reasonable carbon-nitrogen (C/N) ratio, and synchronous removal objectives during wastewater treatment. However, its ability to treat municipal wastewater (MW) with varying low C/N ratio, low NH 4 + concentration, along with managing sludge bulking and loss are still unclear. Against this backdrop, this study investigated the performance of an Upflow Microaerobic Sludge Bed Reactor (UMSR) treating MW characterized by varying low C/N ratios and low NH 4 + concentrations. The study also thoroughly examined associated sludge bulking and loss, pollutant removal efficiencies, sludge settleability, microbial community structures, functional gene variations, and metabolic pathways. Findings revealed that the effluent NH 4 +-N concentration gradually decreased to 0 mg/L with a decrease in the C/N ratio, whereas the effluent COD was unaffected by the influent, maintaining a concentration below 50 mg/L. Notably, TN removal efficiency reached 90% when C/N ratio was 3. The decrease in the C/N ratio (C/N ratio was 1) increased microbial community diversity, with abundances of AOB, AnAOB, aerobic denitrifying bacteria, and anaerobic digestion bacteria reaching 8.34%, 0.96%, 5.07%, and 9.01%, respectively. Microorganisms' metabolic pathways significantly shifted, showing increased carbohydrate and cofactor/vitamin metabolism and decreased amino acid metabolism and xenobiotic biodegradation. This study not only provides a solution for the effluent of different pre-capture carbon processes but also demonstrates the UMSR's capability in managing low C/N ratio municipal wastewater and emphasizes the critical role of microbial community adjustments and functional gene variations in enhancing nitrogen removal efficiency. [Display omitted] • Microaerobic bed suited variable and low C/N ratio wastewater. • TN removal reached 90% when influent C/N ratio was 3. • Reduced C/N ratio in influent increased microbial diversity. • Microaerobic sludge bed followed carbon capture processes. [ABSTRACT FROM AUTHOR]

Constructed wetlands have been widely employed as a cost-effective and environmentally friendly alternative for treating primary and secondary sewage effluents. In this study, biochar and pyrite were utilized as electron donor substrates in intermittent-aerated vertical flow constructed wetlands to strengthen the nutrient and heavy metals removal simultaneously, and the response of nutrient reduction and microbial community to heavy metals stress was also explored. The results indicated that biochar addition exhibited a better nitrogen removal, while pyrite addition greatly promoted the phosphorus removal. Moreover, the high removal efficiencies of Cu2+, Pb2+ and Cd2+ (above 90%) except for Zn2+ were obtained in each system. However, the exposure of heavy metals decreased phosphorus removal while had little effect on nitrogen removal. The influent load and intermittent aeration implementation led to a significant shift in microbial community structures, but microbial biodiversity and abundance decreased under the exposure of heavy metals. Particularly, Thiobacillus and Ferritrophicum , associated with sulfur autotrophic denitrification and iron autotrophic denitrification, were more abundant in pyrite-based wetland systems. • Biochar and pyrite addition was beneficial to nitrogen and phosphorus removal. • Biochar-mediated heterotrophic denitrification played significant role in enhancing total nitrogen removal. • Exposure to heavy metals had little impact on denitrification but hindered phosphorus removal. [ABSTRACT FROM AUTHOR]

Boosting acetate production from waste activated sludge (WAS) fermentation is often hindered by the inefficient solubilization in the hydrolysis step and the high hydrogen pressure ( p H 2) during the acidogenesis of C3–C5 short-chain fatty acid (SCFAs), i.e., propionate (HPr), butyrate (HBu) and valerate (HVa). Therefore, this study employed persulfate (PS) oxidation and C3–C5 incomplete-oxidative sulfate reducing bacteria (io-SRB) metabolizers to tailor SCFAs conversion from WAS fermentation. The decomposition efficiency, performance of SCFAs production was investigated. Results showed that the PS significantly promoted WAS decomposition, with a dissolution rate of 39.4%, which is 26.0% higher than the un-treated test. Furthermore, SCFAs yields were increased to 462.7 ± 42 mg COD/g VSS in PS-HBu-SRB, which was 7.4 and 2.2 times higher than that of un-treated and sole PS tests, respectively. In particular, the sum of acetate and HPr reached the peak value of 85%, indicating that HBu-SRB mediation promoted the biotransformation of HBu and macromolecular organics by reducing the p H 2 restriction. Meanwhile, sulfate radical (SO 4 ∙-)-based oxidation (SR-AOPs) was effective in the decomposition of WAS, the oxidative product, i.e., sulfate served the necessary electron acceptor for the metabolism of io-SRB. Further analysis of Mantel test revealed the cluster of the functional genus and their interaction with environmental variables. Additionally, molecular ecological network analysis explored the potential synergistic and competitive relationships between critical genera. Additionally, the potential synergistic and competitive relationships between critical genera was explored by molecular ecological network analysis. This study provides new insights into the integration of SR-AOPs with microbial mediation in accelerating SCFAs production from WAS fermentation. [Display omitted] • Integration of SR-AOPs and io-SRB mediation tailored SCFAs conversion from WAS. • SR-AOPs efficiently promoted WAS decomposition with hydrolysis rate increased by 26%. • HBu-SRB promoted C2–C3 SCFAs conversion by reducing the p H 2 restriction. • Synergetic relationship among io-SRB and fermentative genera was revealed. • Thermodynamic mechanism of acetate-oriented conversion by io-SRB was explored. [ABSTRACT FROM AUTHOR]

This study aimed to extract orthophosphate (ortho-P) from lipid-rich waste AF liquor (AFL) by Mg/Al layered double hydroxides (Mg/Al LDHs) adsorption, evaluate the influence of carbonate and investigate adsorption mechanisms. The carbonate influence experiment using synthetic P-rich wastewater indicated that low carbonate level was favorable for P extraction by LDHs. And then, real AFL rich in volatile fatty acids (VFAs), carbonate and ortho-P was applied as adsorbate to explore the Mg/Al LDHs adsorption performance. Experimental results indicated that 4 g/L Mg/Al LDHs could extract 88.3% of ortho-P from the AFL with low carbonate level (4829.83 mg CaCO 3 /L), and the adsorption quantity was 62.99 mg P/g LDHs, however, negligible VFAs were extracted. Kinetics and mechanisms analysis indicated that adsorption of P onto Mg/Al LDHs was a rapid physiochemical process, including ion exchange and surface adsorption. Finally, the nutrients release test confirmed the slow-release property of intercalated P. [Display omitted] • Mg/Al LDHs acted as adsorbent to collect P from anaerobic fermentation liquor. • More than 88% of orthophosphorus was captured by 4 g/L Mg/Al LDHs. • Ion exchange and surface adsorption were the main adsorption mechanisms. • Low carbonate level was favorable for P and volatile fatty acids separation by LDHs. [ABSTRACT FROM AUTHOR]

Bioelectrochemical systems were proposed as a promising approach for the efficient valorization of biomass into 6–8 carbon atom medium-chain fatty acids (MCFAs), the precursors for high value-added chemicals or renewable energy, via acetyl-CoA-mediated chain elongation (CE). To achieve CE processes, exogenous electron donors (EDs), e.g., ethanol or lactic acid, were normally prerequisites. This research built a microbial electrolysis cell (MEC) for MCFAs biosynthesis from acetate without exogenous EDs addition. A wide range of applied voltages (0.6–1.2 V) was first employed to investigate the bioelectrocatalyzing response. The results show that caproate and butyrate were the main products formed from acetate under different applied voltages. Maximum caproate concentration (501 ± 12 mg COD/L) was reached at 0.8 V on day 3. Under this applied voltage, hydrogen partial pressure stabilized at about 0.1 bar, beneficial for MCFA production. Electron and carbon balances revealed that the electron-accepting capacity achieved 32% at 0.8 V, showing the highest interspecies electron transfer efficiency. Most of the carbon was recovered in the form of caproate (carbon loss was 9%). MiSeq sequencing revealed Rhodobacter and Clostridium_sensu_stricto playing the crucial role in the biosynthesis of caproate, while Acetobacterium , Acetoanaerobium , and Acetobacter represented the main ED contributors. Four available flora, i.e., homo-acetogen, anaerobic fermentation bacteria, electrode active bacteria, and nitrate-reducing bacteria, interacted and promoted caproate synthesis by molecular ecological network analysis. [Display omitted] • Optimal applied voltages for caproate production in MECs was firstly elucidated. • Hydrogen/ethanol in situ generated served as EDs without exogenous EDs addition. • Electron acceptability, carbon balance and hydrogen partial pressure were analyzed. • Caproate concentration and specificity achieved maximum under 0.8 V. • Synergistic and competitive interactions among functional microflora were revealed. [ABSTRACT FROM AUTHOR]

The development of slow-release carbon sources is an effective biological treatment to remove nutrients from wastewater with low carbon-to-nitrogen ratio (C/N). Most filling-type slow-release carbon could not fulfil the needs of current wastewater treatment plants (WWTPs) process. And most adding-type slow-release carbon sources were prepared using some expensive chemical materials. In this study, combining the advantages of the aforementioned types, a novel adding-type wastepaper-flora (AT-WF) slow-release carbon source was proposed, aiming to realise wastepaper recycling in WWTPs. The screening and identification of the mixed flora, AT-WF carbon source release behaviour, and denitrification performance were investigated. The results showed that through the proposed screening method, a considerable proportion of cellulose-degradation-related genera was enriched, and the cellulose degradation ability and ratio of readily available carbon sources of flora T4, S4 and S5 were effectively strengthened. AT-WF had significant carbon release ability and stability, with an average total organic carbon (TOC) release of 8.82 ± 2.36 mg/g. Kinetic analysis showed that the entire carbon release process was more consistent with the first-order equation. Piecewise fitting with the Ritger-Peppas equation exhibited that the rapid-release (RR) stage was skeleton dissolution and the slow-release (SR) stage was Fick diffusion. Denitrification efficiency can achieve a high average removal efficiency of 94.17%, which could theoretically contribute 11.2% more to the total inorganic nitrogen (TIN) removal. Thus, this study indicated that AT-WF could be utilised as an alternative carbon source in WWTPs. [Display omitted] • A novel adding-type biological slow-release carbon source AT-WF was proposed. • Short-term organic nitrogen source stimulation enhanced the function of the flora. • AT-WF had great ability of carbon release and realized the stable NO 3 −-N removal. • The production of AT-WF provided a new way for wastepaper recycling in WWTPs. [ABSTRACT FROM AUTHOR]

Sulfadiazine (SDZ) is one of the most representative sulfonamides antibiotics, and its biodegradation has become a research hotspot in recent years. The present study innovatively adopted a microbial fuel cells with a Nickel (Ⅱ) and Manganese (Ⅱ)-decorated graphite felt bioanode (Ni(Ⅱ)/Mn (Ⅱ)-MFCs) to remove SDZ. The results demonstrated that the Ni(Ⅱ)/Mn (Ⅱ)-MFCs exhibited improved electrochemical performance, with a higher power density (742.98 ± 58.33 mW/m2) compared to the control MFCs (678.34 ± 52.87 mW/m2), an overall lower anode potential, and a larger double layer area (cyclic voltammetry). After 5 months of operation, approximately 97.95% of 30 mg/L SDZ was degraded within 120 h, which was 11.46% higher than that of the control MFCs. Moreover, SDZ and its byproducts could be better mineralized in the Ni(Ⅱ)/Mn (Ⅱ)-MFCs than the control, and the biotoxicity of SDZ towards Escherichia coli and Vibro qinghaiensis sp. Q67 could be greatly decreased after treatment with the modified MFCs. Based on the metabolites, we hypothesized that the chemical reactions hydroxylation, ammoxidation, SO 2 -extrusion, sulfur-reduction, etc. played a significant role in SDZ biodegradation. A microbial community analysis revealed that Dechloromonas (2.37%), Denitratisoma (5.32%) and Lentimicrobium (26.35%) were the dominant functional microbes in the Ni(Ⅱ)/Mn (Ⅱ)-MFCs. This study may provide insights and a theoretical basis for the biodegradation of sulfonamides and thus may facilitate further investigations and relevant findings. • Anode material of MFCs was decorated with Ni(Ⅱ) and Mn (Ⅱ). • Ni(Ⅱ)/Mn (Ⅱ)-MFCs accelerated the biodegradation and mineralization of SDZ. • Electrogenesis performance of Ni(Ⅱ)/Mn (Ⅱ)-MFCs was superior to control MFC. • The metabolic pathways of SDZ in Ni(Ⅱ)/Mn (Ⅱ)-bioanode were suggested. • The dominant flora of Ni(Ⅱ)/Mn (Ⅱ)-MFCs was linked to SDZ removal and electrogenesis. [ABSTRACT FROM AUTHOR]

Photocatalytic removal of NH 3 –N is expected to be an alternative to the biological method that accompanied with high energy consumption and secondary pollution. However, NH 3 –N is always oxidized into nitrate and nitrite during the photocatalytic processes, which also need to be removed from the water. Herein, the g-C 3 N 4 /rGO/TiO 2 Z-scheme photocatalytic system was prepared and used for the NH 3 –N removal. The results showed the rate constant of NH 3 –N conversion on it was 0.705 h−1, 1.7 times as high as that on g-C 3 N 4 /TiO 2 , and most of the NH 3 –N were converted into gaseous products. And the experiment result indicated NH 3 –N and NO 3 − in water could enhance the removal of each other. According to the results, the main reaction mechanism is speculated as: ·OH radicals and ·O 2 − radicals were generated on TiO 2 and oxidized the NH 3 –N into NO 3 −, and the latter was reduced into non-toxic N 2 on the conduction band of g-C 3 N 4. Finally, NH 3 –N removal performance for actual coking wastewater was investigated, and the stability of the photocatalyst was tested. This work provides some theoretical basis for the two-step degradation of pollutants by Z-scheme photocatalytic system. • NH3–N removal was realized by photocatalytic nitrification-denitrification process. • g-C3N4/rGO/TiO2 was used for treatment of actual coking wastewater. • The stability of g-C3N4/rGO/TiO2 used in actual wastewater was tested. • Interaction of NH3–N and NO3 during the photocatalytic process was investigated. [ABSTRACT FROM AUTHOR]

Electro-fermentation (EF) is an attractive way to implement the chain elongation (CE) process, by controlling the fermentation environment and reducing the dosage of external electron donors (EDs). However, besides the coexistence performance of external EDs and electrode, applications of EF technology on the fermentation broth containing both EDs and electron acceptors during CE process, are all still limited. The current study investigated the contribution of EF to caproate production, under different acetate: ethanol ratios (R A/E). The effect of multiple EDs, both from ethanol and the bio-cathode, on caproate production, was also assessed. A proof-of-concept, based on experimental data, was presented for the EF-mediated ethanol-driven CE process. Experimental results showed that ethanol, together with the additional electron donors from the bio-cathode, was beneficial for the stable caproate production. The caproate concentration increased with the decrease of R A/E , while the bio-cathode further contributed to 10.7%–26.1 % increase of caproate concentration. Meanwhile, the hydrogen partial pressure tended to 0.10 ± 0.01 bar in all controlled EF reactors, thus favoring caproate production. This was attributed to the increased availability EDs, i.e., hydrogen and ethanol, generated by the electrode and electrochemically active bacteria (EAB), which might create multiple additional pathways to achieve caproate production. Molecular ecological networks analysis of the key microbiomes further revealed underlying cooperative relationships, beneficial to the chain elongation process. The genus Clostridium_sensu_stricto , as the dominant microbial community, was positively related to acetogens, EAB and fermenters. [Display omitted] • The coexistence performance of external EDs and electrode was firstly elucidated. •External ethanol addition was conducive to the stable caproate production. •Caproate concentration showed rising trend with the increase of ethanol. •The introduction of bio-cathode contributed to 10.7%-26.1% increase. •Synergistic relationship of Clostridium sensu stricto and other microbes was revealed. [ABSTRACT FROM AUTHOR]

Extraction of short-chain fatty acids (SCFAs) from fermentation liquid of waste activated sludge (WAS) is the key bottleneck hindering its application as electron donor in denitrification. This study explores the feasibility of polyether-type polyurethane (PU)-modified layered double hydroxides (LDHs, prepared using eggshell waste as calcium source) in SCFAs adsorbing from WAS fermentation liquid (SFL). The adsorption parameters were first optimized by adsorption tests using artificial fermentation liquid (AFL). Then, adsorption kinetics, thermodynamic and isotherms were explored to further understand the adsorption mechanism. It revealed that SCFAs absorption by PU-LDHs from SFL was an endothermic and spontaneous process with positive enthalphy (ΔH◦) values and negative Gibbs free energy (ΔG◦) values. In addition, the maximum adsorption capacity of 208.0 mg SCFAs/g PU-LDHs was obtained from the Langmuir isotherm. Noting that both soluble carbohydrates and soluble proteins were simultaneously extracted, with efficiencies of 30.9%, 6.2%, respectively, compared with 62.9% SCFAs. The reuse tests confirmed that the prepared PU-LDHs can be used at least three times with high adsorptive capacity. With PU-LDHs-loaded SFL as external carbon source in the biodenitrification process, a denitrification rate of 0.014 mg NO 3 −-N/mg mixed liquid suspended solids (MLSS)·d was recorded. This study provided a sound basis for the preparation of cost-effective biodenitrification carbon source from SFL by a novel adsorbent. Image 1 • A waste-to-resource concept was established for eggshell waste and WAS treatment. • PU-LDHs can be repeatedly used as the carrier of SCFAs with high adsorption capacity. • PU-LDHs retained SFL showed good performance as electron donor in denitrification. • Recycle test confirmed PU-LDHs can be reused multiple times for biodenitrification. [ABSTRACT FROM AUTHOR]