Wastewater Removal Research Articles

Adsorption of fluoride ion on Al/La modified acidified attapulgite composite materials

This study developed a novel fluoride ion adsorbent material (Al/La-A) for efficient removal of fluoride ions in water. The crystal structure, elemental composition, surface morphology, specific surface area, thermal stability and surface electronegativity before and after modification were explored using FTIR, XRD, XPS, SEM-EDS, BET, TG-DSC, and zeta potential measurements. Results showed that the fluoride ion adsorption capacity of Al/La-A reached 130.42 mg/g, with the surface area increasing from 65.66 m2/g to 111.68 m2/g, respectively, compared to unmodified attapulgite. Al/La-A maintained excellent fluoride ion removal performance over a wide pH range, with the best adsorption at pH 2. Coexisting ion experiments indicated weak competitive adsorption effects of Cl-, SO42-, and HCO3–, with fluoride ion adsorption remaining above 100 mg/g in the presence of different concentrations of coexisting anions. After 5 adsorption–desorption cycles, Al/La-A exhibited strong adsorption capacity and reusability. The fitting of Langmuir adsorption model and pseudo-second-order kinetic model to the adsorption of fluoride ions on Al/La-A indicated that the adsorption of fluoride ions on Al/La-A was primarily monolayer chemical adsorption. The adsorption mechanism of fluoride ions involved electrostatic interactions, ion exchange, and coordination complexation. This study provides a new research approach for the optimal utilization of attapulgite-based adsorbent materials and the efficient removal of fluoride-containing wastewater.

Electrocoagulation treatment for Remazol Brilliant Blue R (Reactive Blue 19) removal of textile dye simulated wastewater using iron-aluminum electrodes

Abstract The presence of non-biodegradable dyes, such as Remazol Brilliant Blue R (Reactive Blue 19), in wastewater poses a significant environmental challenge. This study investigates the application of electrocoagulation using iron-aluminum (Fe-Al) electrodes to efficiently remove Reactive Blue 19 dye from simulated textile dye wastewater. It considers various parameters such as electrode material, current, stirring speed, as well as the influence of sodium chloride acting as a supporting electrolyte to enhance conductivity. Additionally, it evaluates the economic feasibility through electrode consumption analysis. The experimental setup involved a designed reactor with aluminum and iron electrodes arranged at bipolar parallel connection, along with a 30-minute electrocoagulation process conducted at ambient temperature and subsequent filtration of the treated wastewater for UV-VIS analysis. The optimal parameter combination obtained consists of Fe-Al electrode material, a 3 A current, and a 200-rpm stirring speed, achieving 96.87% dye removal. Furthermore, extending the operating time to 60 minutes improved the removal by 99.15%. Under these optimal conditions, the energy consumption measured was 36 kWh/m3. The high dye removal rate obtained shows the effectiveness of this electrocoagulation process in treating Reactive Blue 19 simulated wastewater. A t-test, employed as a hypothesis testing technique with a significance level of 0.05, confirmed the optimal levels of the factors and interactions within the treatment process. A remarkable coefficient of determination of 0.9794 in the dye removal sensitivity analysis signifies a strong goodness of fit, indicating that these three (3) parameters collectively explain how they affect the outcome while accounting for dye removal efficiency variation. These results showed that electrocoagulation is a promising technology for treatment of Reactive Blue 19 dye wastewater.

Synthesis of carbon-metal interface ilmenite type nanostructures using ultrasonication-assisted sol-gel process for visible-light-driven hydrogen production from methanol and antibiotic wastewater removal

In this study, a new carbon-metal (C-Ti) interface was synthesized by chemically connecting perovskite ilmenite-type (FeTiO) nanostructures with carbon produced from biowaste (BC) using a simple sol-gel process assisted by ultrasonication. This interface can use visible light to produce hydrogen from hydrocarbons (methanol solution) and remove the antibiotic ciprofloxacin (CIF) from wastewater. Following optimization, BC15@FeTiO nanostructures displayed the highest visible light active photocatalytic hydrogen generation rate of 415.43 μmol·h−1·g−1. Furthermore, these nanostructures removed the CIF rate at 91.09 % for 120 minutes. The efficient electron transfer between BC and FeTiO via the chemically connected C-Ti interface promotes the formation of visible-light active photocatalytic hydrogen generation from methanol and the removal of antibiotic CIF into innocuous byproducts. This study also offers a new, low-cost carbon material made chemically from biowaste.

Nonmetallic element-doped graphene aerogel enhances industrial wastewater removal performance via a multifield coupled system of adsorption-catalytic degradation: Insights from experiments and theoretical calculations

In this paper, a multifield coupled system of synergistic adsorption and photo-Fenton degradation was constructed, and BiFeO3-modified nonmetallic element-doped graphene aerogel composites (BiFeO3/X-rGA) were prepared to realize the advanced treatment of phenol and coking wastewater by utilizing consistent adsorption and catalytic degradation sites. Nonmetallic element-doped graphene formed more defective active sites and changed the planar carbon layer structure, which enhanced the adsorption performance of pollutants on the basis of graphene face adsorption and π-π adsorption. Moreover, element doping also modulated the localized electronic structure of graphene and promoted carrier separation, which in turn enhanced the photo-Fenton degradation activity. The phenol degradation rate constant of BiFeO3/P-rGA was 3.29 times greater than that of BiFeO3/rGA, and the removal efficiency in coking wastewater was also greatly improved. In coupled systems, hydroxyl radicals are the predominant active species, and the mechanism by which nonmetallic modifications promote the synergistic performance of graphene aerogel adsorption and catalytic degradation systems was refined based on experimental and DFT results, providing a new idea for the advanced treatment of wastewater.

Influence and mechanism of typical transition metal ions on the denitrification performance of heterotrophic nitrification-aerobic denitrification bacteria

To investigate the inhibitory effects of various transition metal ions on nitrogen removal and their underlying mechanisms, the single and combined effects of Cu2+ Ni2+ and Zn2+ on Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria Acinetobacter sp. TAC-1 were studied in a batch experiment system. The results revealed that increasing concentrations of Cu2+ and Ni2+ had a detrimental effect on the removal of ammonium nitrogen (NH4+-N) and total nitrogen (TN). Specifically, Cu2+ concentration of 10 mg/L, the TN degradation rate was 55.09%, compared to 77.60% in the control group. Cu2+ exhibited a pronounced inhibitory effect. In contrast, Zn2+ showed no apparent inhibitory effect on NH4+-N removal and even enhanced TN removal at lower concentrations. However, when the mixed ion concentration of Zn2++Ni2+ exceeded 5 mg/L, the removal rates of NH4+-N and TN were significantly reduced. Moreover, transition metal ions did not significantly impact the removal rates of chemical oxygen demand (COD). The inhibition model fitting results indicated that the inhibition sequence was Cu2+ > Zn2+ > Ni2+. Transcriptome analysis demonstrated that metal ions influence TAC-1 activity by modulating the expression of pivotal genes, including zinc ABC transporter substrate binding protein (znuA), ribosomal protein (rpsM), and chromosome replication initiation protein (dnaA) and DNA replication of TAC-1 under metal ion stress, leading to disruptions in transcription, translation, and cell membrane structure. Finally, a conceptual model was proposed by us to summarize the inhibition mechanism and possible response strategies of TAC-1 bacteria under metal ion stress, and to address the lack of understanding regarding the influence mechanism of TAC-1 on nitrogen removal in wastewater co-polluted by metal and ammonia nitrogen. The results provided practical guidance for the management of transition metal and ammonia nitrogen co-polluted water bodies, as well as the removal of high nitrogen.

Coupling effects of aureomycin and zinc ion on nitrification process and nitrification enzymes during the biological nitrogen removal

Aureomycin and Zinc ion (Zn2+) are common antibiotics and heavy metals that exist in livestock wastewater. The coupling effects of Aureomycin and Zn2+ on the nitrification process and nitrification function enzymes are crucial for controlling nitrogen removal in livestock wastewater. However, rare studies were focused on the coupling effects of Aureomycin and Zn2+ on nitrification. This study employed a direct equipartition ray method to investigate the coupling effects of Aureomycin and Zn2+ on nitrification. The results suggested three different ratios of Aureomycin and Zn2+ affected nitrification performance differently. Ratio 1 and Ratio 2 exhibited a promotion effect with low concentrations and an inhibition effect with high concentrations on nitrification performance. The critical concentration for Ratio 1 and Ratio 2 were 5.00 mg L−1 and 1.90 mg L−1, respectively. Ratio 3 exhibited both time-dependent and concentration-dependent inhibitory effects on nitrification performance. The maximum inhibitory efficiency on nitrification performance was 90.0%, with a concentration of 34.5 mg L−1 at 96.0 h. The effects of binary mixture on nitrogen removal performance were attributed to the effects of binary mixture on nitrite oxidase activity. The qualitative evaluation of the concentration addition model and independent action model indicated Aureomycin and Zn2+ showed a synergistic effect with strong concentration-dependent and time-dependent in the whole concentration area. The synergistic effect of Aureomycin and Zn2+ on nitrite oxidase activity mainly depended on the concentration of Aureomycin. This study offers new insights into the effects of antibiotics and heavy metals on the biological nitrogen removal process.

Microwave-assisted utilization of kraft lignin-derived activated carbon for efficient dye removal

The use of conventional petrochemical-based carbon precursors, high-energy pyrolysis-based carbonization processes, and difficulties in designing sustainable processes using activated carbon have hampered the sustainable production of activated carbon and its use in wastewater treatment processes. In this study, to overcome these limitations in the production and application of existing petrochemical-based activated carbon as a water treatment material, biomass-based kraft lignin was used as an eco-friendly carbon precursor. In addition, to increase process efficiency, activated carbon was prepared using energy-intensive microwave-assisted carbonization and applied to the dye wastewater removal process. First, kraft lignin was successfully converted into microporous activated carbon within 10 min through microwave-assisted carbonization and chemical activation processes. As a result, kraft lignin-derived activated carbon showed excellent adsorption capacity for MB of 543.82 mg/g and AO of 548.54 mg/g, respectively. In addition, through heat treatment using microwaves (low power conditions of 450 W, treatment within 2 min), it was possible to successfully achieve thermal decomposition of the adsorbed dye and recovery of the pores and texture properties of activated carbon. Finally, kraft lignin-derived activated carbon showed an excellent reuse efficiency of more than 97 %, even under the condition of reuse 5 times.

Synthesis and fabrication of magnetically separable phosphate-modified magnetic chitosan composites for lead(II) selective removal from wastewater

To address the urgent need for efficient removal of lead-containing wastewater and reduce the risk of toxicity associated with heavy-metal wastewater contamination, materials with high removal rates and easy separation must be developed. Herein, a novel organic-inorganic hybrid material based on phosphorylated magnetic chitosan (MSCP) was synthesized and applied for the selective removal of lead (II) from wastewater. From the characterization and the experimental results can be obtained that the magnetic saturation strength of MSCP reaches 14.65 emu/g, which can be separated quickly and regenerated readily, and maintains high adsorption performance even after 5 cycles, indicating that the adsorbent possesses good magnetic separation performance and durability. Also, MSCP showed high selective adsorption performance for lead in the multiple metal ions coexistence solutions at pH 6.0 and room temperature, with an adsorption coefficient SPb-MSCP of 78.85%, which was much higher than that of MSC (the SPb-MSC was 11.59%). Additionally, in the single lead system, the sorption characteristics of Pb(II) on MSCP and MCP had obvious pH-responsiveness, and their adsorption capacity increased with the increase of solution pH, reaching the maximal values of 80.19 and 72.68 mg/g, respectively. It is noteworthy that the acid resistance of MSCP with an inert layer coated on the core is significantly improved, with almost no iron leaching from MSCP over the entire acidity range, while MCP has 7.63 mg/g of iron leaching at pH 1.0. Significantly, MSCP exhibited a maximum adsorption capacity of 102.04 mg/g, which matches the Langmuir model at pH 6.0 and 298.15 K, and points to the pseudo-second-order kinetics of the chemisorption process of Pb(II) on MSCP. These findings highlight the great potential of MSCP for Pb(II) removal from aqueous solution, making it a promising solution for Pb(II) contamination in wastewater.

Biosynthesis of Fe/Pd Bimetallic Nanoparticles and Used for Removal of Synthetic Oily Wastewater

Eucalyptus plant leaves aqueous extract was used to produce a green bimetallic Fe/Pd nanoparticles (G-Fe/Pd NPs) catalyst for the degradation of synthetic oily effluent. Using Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), particle size, and a zeta potential analyzer, the synthesized G Fe/Pd NPs were evaluated. G-Fe/Pd NPs have been found to contain nanoparticles, with a mean size of 182 nm and a surface area of 5.106 m2/g. The resulting nanoparticles were then used as a catalyst for a Fenton-like reaction. The amount of green catalyst G-Fe/Pd NPs (0.125-0.5 g/L), H2O2 concentration (15-37.5 mmol/L), pH (3-7), and temperature (25-45°C) all have a significant impact on the degradation efficiency of synthetic oily wastewater. Batch experiments showed that 88.9% degraded chemical oxygen demand (COD) from synthetic oily wastewater within the optimum conditions of peroxide concentration, catalyst dose, pH, and temperature which were 30.0 mmol/L, 0.375 g/L, 3, and 45℃ respectively along with 60 min contact time. The results of kinetic models showed that oily wastewater removal followed the Behnajady-Modirshahla-Ghanbary (BMG) model. Finally, the thermodynamic study of the reaction was also examined and concluded to endothermic reaction with an enthalpy of 37.39 kJ/mol.

A novel highly dispersed calcium silicate hydrate nanosheets for efficient high-concentration Cu2+ adsorption

Currently, the low cost and effective purification toward heavy metal ions in wastewater has garnered global attention. Herein, we used hydrothermal method to prepare highly dispersed calcium silicate hydrate in fluorite tailings. And the stacking thickness of calcium silicate hydrate layered morphology was less than 5 nm. For high concentration Cu2+ purification investigation in wastewater, we found that the equilibrium adsorption capacity reached 797.92 mg/g via the CSH with 3:2 Ca/Si molar ratio, be 1.43–21.8 times than that of reported data. Therein, the metal-metal exchange and deposition are the primary pathways for Cu2+ adsorption, and electrostatic attraction is the secondary pathway. And the relative ∼100 % removal rate of high-concentration Ni2+ and Cr3+ ions were confirmed via CSH prepared from different tailings. This method offers a cost-effective way to utilize tailings for preparing highly efficient adsorbents toward HMIs removal in wastewater.

Heterogeneous electro-Fenton removal of polyacrylamide in aqueous solution over CoFe2O4 catalyst.

Polyacrylamide (PAM) in environmental water has become a major problem in water pollution management due to its high molecular mass, high viscosity and non-absorption by soil. CoFe2O4 with strong magnetic properties was prepared by solvent-thermal synthesis method and used as the catalyst for the removal on PAM in heterogeneous Electro-Fenton (EF) system. It showed that the removal efficiency of PAM by the heterogeneous EF system using CoFe2O4 catalyst was 92.01% at pH 3 after 120 min. Further studies indicated that ·OH was the most significant active species for the removal of PAM, and the contribution of ·O2- and SO4·- for the removal of PAM was less than 15%. The reusability test and XRD, XPS, FTIR analyses proved that the catalyst had good stability. After a repeated use for five times, the catalyst still had a high PAM removal rate and stable structure. The valence distribution and functional groups of the phase components of the catalyst did not change significantly before and after the reaction. The possible mechanism of catalyst activation of H2O2 was deduced by mechanism investigation. The CoFe2O4 is an efficient and promising catalyst for the removal of PAM wastewater.

Synthesis of Ni decorated MoOx nanorod catalysts for efficient overall urea-water splitting.

Substituting slow oxygen evolution reaction (OER) with thermodynamically favorable urea oxidation reaction (UOR) is considered as one of the feasible strategies for achieving energy-saving hydrogen production. Herein, a uniform layer of NiMoO4 nanorods was grown on nickel foam by a hydrothermal method. Then, a series of Ni-MoOx/NF-X nanorod catalysts comprising Ni/NiO and MoOx (MoO2/MoO3) were prepared through regulating annealing atmosphere and reduction temperature. The optimized Ni-MoOx/NF-3 with a large accessible specific area can act as a bifunctional catalyst for electrocatalytic anodic UOR and cathodic hydrogen evolution reaction (HER). At a current density of 100 mA cm-2, the introduction of urea can significantly reduce the overpotential of Ni-MoOx/NF-3 by 210 mV compared to OER. In addition, Ni-MoOx/NF-3 has a higher intrinsic activity than other catalysts. It only requires -0.21 and 1.38V to reach 100 mA cm-2 in HER and UOR, respectively. Such an excellent performance can be attributed to the synergistic function between Ni and MoOx. The presence of metallic Ni and reduced MoOx in pairs is beneficial for improving the electrical conductivity and modulating the electronic structure, resulting in enhancing the electrocatalytic performance. When assembling Ni-MoOx/NF-3 into an overall urea-water splitting system, it can achieve energy-saving hydrogen production and effective removal of urea-rich wastewater.

Pollutant Removal in Wastewater from Anaerobic Digesters by Water Lettuce (<i>Pistia stratiotes</i> L.) at Both Still-Water and Running-Water Stages

Pollutant Removal in Wastewater from Anaerobic Digesters by Water Lettuce (<i>Pistia stratiotes</i> L.) at Both Still-Water and Running-Water Stages

Bioelectrochemically altering microbial ecology in upflow anaerobic sludge blanket to enhance methanogenesis fed with high-sulfate methanolic wastewater

A bioelectrochemical upflow anaerobic sludge blanket (BE-UASB) was constructed and compared with the traditional UASB to investigate the role of bioelectrocatalysis in modulating methanogenesis and sulfidogensis involved within anaerobic treatment of high-sulfate methanolic wastewater (COD/SO42− ratio ≤ 2). Methane production rate for BE-UASB was 1.4 times higher than that of the single UASB, while SO42− removal stabilized at 16.7%. Bioelectrocatalysis selectively enriched key functional anaerobes and stimulated the secretion of extracellular polymeric substances, especially humic acids favoring electron transfer, thereby accelerating the electroactive biofilms development of electrodes. Methanomethylovorans was the dominant genus (35%) to directly convert methanol to CH4. Methanobacterium as CO2 electroreduction methane-producing archaea appeared only on electrodes. Acetobacterium exhibited anode-dependence, which provided acetate for sulfate-reducing bacteria (norank Syntrophobacteraceae and Desulfomicrobium) through synergistic coexistence. This study confirmed that BE-UASB regulated the microbial ecology to achieve efficient removal and energy recovery of high-sulfate methanolic wastewater.

Combined effect of zinc and cadmium ions on nitrification performance during the biological nitrogen removal of simulated livestock breeding wastewater.

Zinc and cadmium ions are usually found in livestock breeding wastewater, and the mixed ions will have an impact on the biological nitrogen removal. Nitrification performance plays an important role in biological nitrogen removal. In order to investigate the combined effect of zinc and cadmium ions on nitrification performance and to reveal the interactions between zinc and cadmium ions, three concentration ratios of zinc and cadmium ions, as well as 18 different concentration gradients were designed with the direct equipartition ray and the dilution factor method. The effect of pollutants on the nitrification performance of biological nitrogen removal was analyzed by the nonlinear regression equation, and the concentration-addition model was conducted to probe into the relationship between the mixed pollutants and the nitrification performance. The results showed that the effect on nitrification performance increased significantly with the increase of reaction duration and pollutant concentration, which indicated that the effects are concentration-dependent and time-dependent. The concentration-addition model suggested that the interactions between zinc and cadmium ions with different concentration ratios were mainly antagonistic, and as the percentage of cadmium ions in the mixtures increased, the antagonism between the mixtures became stronger. This study will provide a relevant theoretical basis for the regulation of the ratios and concentrations of heavy metal ions during the biological treatment of livestock breeding wastewater.

Treatment of Wastewaters with Different Ammonium Concentrations in a Sequencing Batch Reactor by Nitritation and Denitritation Processes

In the treatment of industrial and municipal wastewaters, biological nitrification and denitrification processes have been widely applied methods. However, in recent years, experimental studies have been carried out on nitritation and denitritation processes in order to reduce the cost of wastewater treatment. In this study, the removal of synthetic wastewaters containing ammonium at various concentrations through nitritation and denitritation processes was investigated in a sequence batch reactor (SBR). The SBR was operated at a low dissolved oxygen concentration of 0.7±0.2 mg/L, while the initial pH level and temperature were kept constant at 7.5 and 25 ℃, respectively, which were below the defined optimal level for nitritation. For the initial concentrations of 100, 150, and 200 mg NH4-N/L, 91, 142, and 180 mg NOx-N were produced, respectively with the specific nitritation rates of 0.69, 0.95, and 0.81 mg NH4-N/mg MLVSS.hour. Considering the operating conditions of nitritation, approximately NO2-N/NOx-N ratio of 80% could be considered as successful with the combined effect of DO limitation and NH3 inhibition on the nitrite oxidizing bacteria. During the first days of nitritation and denitritation processes, change of nitrogen concentrations was negligible because the adaptation of organisms to the oxic and anoxic conditions. After completing nitritation stage, denitritation was carried out by using methanol as an electron donor for the initial concentrations of 91, 142, and 180 mg/L of NOx-N in 96, 120 and 264 hours of reaction times, respectively.

Optimization of dissolved oxygen in the removal of wastewater generated in a sawmill using response surface methodology (RSM)

Optimization of dissolved oxygen in the removal of wastewater generated in a sawmill using response surface methodology (RSM)

Manganese sulfide-sulfur and limestone autotrophic denitrification system for deep and efficient nitrate removal: Feasibility, performance and mechanism

Despite the great potential of sulfur-based autotrophic denitrification, an improvement in nitrate removal rate is still needed. This study used the desulfurized products of Mn ore to develop the MnS-S0-limestone autotrophic denitrification system (MSLAD). The feasibility of MSLAD for denitrification was explored and the possible mechanism was proposed. The nitrate (100 mg/L) was almost removed within 24 h in batch experiment in MSLAD. Also, an average TN removal of 98 % (472.0 mg/L/d) at hydraulic retention time of 1.5 h in column experiment (30 mg/L) was achieved. MnS and S0 could act as coupled electron donors and show synergistic effects for nitrate removal. γ-MnS with smaller particle size and lower crystallinity was more readily utilized by the bacterium and had higher nitrate removal efficiency than that of α-MnS. Thiobacillus and Sulfurimonas were the core functional bacterium in denitrification. Therefore, MnS-S0-limestone bio-denitrification provides an efficient alternative method for nitrate removal in wastewater.

Application of Cotton Stalk as an Adsorbent for Copper(II) Ions in Sustainable Wastewater Treatment

The capacity of untreated cotton stalk to remove and adsorb Cu2+ ions in synthetic and natural aqueous solutions was evaluated. The influence of three sensitive parameters of the adsorption process—solution pH, adsorbent dosage, and contact time—on the percentage of Cu2+ removal in agricultural wastewater, livestock wastewater, and synthetic samples was studied. Physicochemical and morphological properties were studied using thermogravimetry, Fourier infrared spectrophotometry, and scanning electron microscopy. The elemental composition, proximal composition, zero charge point, and acid–base sites were determined. In addition, kinetic studies were performed, and the adsorption equilibrium was analyzed. The optimum conditions for Cu2+ adsorption were the following: solution pH = 5.5, adsorbent dosage of 0.6 g, and contact time of 60 min. Under these conditions, the percentage of Cu2+ removal in synthetic samples was 66.5% when the initial copper concentration was 50 mg/L. The removal percentage in agricultural and livestock wastewater samples was 87.60% and 85.05%, respectively, when the initial copper concentration was 25 mg/L. The adsorption data are consistent with the Freundlich isotherm model, which achieved a quadratic fit of 0.991 compared to 0.5542 for the Langmuir model. The experimental results indicate that the adsorption adequately fits the pseudo-second-order kinetic model. The results suggest that cotton stalks are a promising adsorbent for the ecological and economical removal of Cu2+ in wastewater. This research, therefore, provides relevant information that contributes to the sustainable management of agricultural waste and instills hope for a reduction in water pollution from heavy metals derived from agricultural activities.

Carbon-ferrous-sulfur mixotrophic denitrification driven by polyferric sulfate (PFS)-conditioned recovered sludge fermentation liquor enhanced nitrogen removal in woolen wastewater

Reducing pollution and carbon emissions synergistically in wastewater treatment is an important part of carbon neutralization. Recycling carbon sources (CSs) in sludge to refeed denitrification has been considered a promising sustainable pathway, but it is limited by CSs purification and recovery. This study evaluated the effects of polyferric sulfate (PFS), polyaluminum chloride (PAC), and polyacrylamide (PAM) conditioning on fermentation CSs recovery and denitrification efficiency. Results indicated PFS-conditioned recovered fermentation liquor showed higher denitrification efficiency for woolen wastewater. CSs recovery test showed that PFS conditioning improved the purity of high-bioavailability CSs by depleting fewer short-chain fatty acids (SCFAs) and removing more total nitrogen (TN), total phosphorus (TP), and humic acids. Under the 0.05 g/gTSS PFS conditioning and recovery, the preservation of soluble chemical oxygen demand (SCOD) and SCFAs were 71.00 % and 84.36 %, respectively, and the nitrate degradation rate achieved 3.19 mgNO3−·h−1·gVSS−1. Importantly, Fe(III) dissociated from PFS oxidized the S2− from woolen wastewater, and generated Fe(II) and S0, which composed a synergistic electron donor system together with SCFAs. They constituted a mixotrophic denitrification dominated by heterotrophic denitrification and reinforced by ferrous and sulfur-autotrophic denitrifications, which contributed 69.56, 17.72, and 12.72 % to nitrogen removal, respectively. In addition, the refeeding of PFS-conditioned recovered fermentation liquor promoted the proliferation of microorganisms involved in iron/sulfur autotrophic denitrification and the abundance of denitrification functional genes, especially the napA, nirS, cnorB, qnorB, and nosZ, forming an efficient Carbon-Ferrous-Sulfur hybrid denitrifiers community to enhanced nitrogen removal from woolen wastewater.