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The feasibility of using Fe 0 /S 2 O 8 2− conditioning (zero valence iron (ZVI)/persulfate (ps)) integrated with horizontal electro-dewatering (HED) to improve the dewaterability of activated sludge (AS) was evaluated. The removal and migration of free and bound water in the ZVI/ps–HED process were determined, along with the organic matter migration between the solid and liquid phases of AS biosolids. Results showed that the optimum conditioning dosages were determined as 0.35 g ZVI/g dry solids (DS) and 0.15 g ps/g DS on the basis of capillary suction time variation. The lowest final water content (WC) of 83.67% in AS occurred after the HED treatment at 40 V and 120 min as determined using the response surface methodology. Despite the disruption of AS flocs and microbial cells through SO 4 − · oxidation during the ZVI/ps conditioning, the particle size and mass fractal dimension of the AS flocs remained relatively stable as the zeta potential increased from −8.5 mV to −4.6 mV. The coagulation of Fe 3+ from the oxidation of Fe 2+ by ps contributed to the relatively stable condition, which favored the subsequent momentum of the electroosmotic flow. Moreover, the ZVI/ps conditioning decreased the bound water content (BWC, from 1.83 g/g DS to 1.38 g/g DS) and increased the free water content (FWC, from 60.27 g/g DS to 60.91 g/g DS), indicating a transformation from free water to bound water. After the ZVI/ps–HED process, the FWC and BWC were removed significantly with ratios of 96.32% and 79.78%, respectively. Along with water removal through the ZVI/ps–HED process, the organic matter in the supernatant/filtrate initially increased and further rose at the HED stage. The analysis of the extracellular polymeric substance (EPS) content showed that the proteins (PNs) and polysaccharides (PSs) at the liquid and solid phases decreased due to oxidative degradation. Furthermore, the ZVI/ps stage significantly reduced the PNs content of slime to 57.22%, the PSs content of EPS to 68.50%, and the PN-like substances in the slime and tightly bound EPS to 74.90% and 52.47%, respectively. In addition, the WC of AS correlated with the contents of PN and microbial by-product-like material in slime, as well as tryptophan in TB-EPS, and the low EPS content in AS indicated good dewaterability. Thus, ZVI/ps should be selected as a pretreatment prior to HED. [ABSTRACT FROM AUTHOR]

Magnetic micro-particles (MMPs) and magnetic field (MF) were utilized as a coupling conditioning unit before dewatering activated sludge (AS) under a horizontal electric field. The removal and migration of free and bound water in AS during coupling magnetic conditioning–horizontal electro-dewatering (CM–HED) were determined. The organic matter migration between the solid and liquid phases of AS biosolids was also analyzed. Results show that MMPs dosage and MF intensity were determined as 0.15 g/g dry solids and 0.065 T for the best dewaterability, respectively. The optimum dewatering conditions for CM–HED with the final water content of 89.98% were 40 V and 120 min as determined using the response surface methodology. MMPs conditioning could induce a slight coagulation among AS flocs, increase the particle size from 85.9 μm to 92.3 μm and decrease mass fractal dimension from 2.18 to 2.07. The MMPs-conditioned AS also showed a network-like structure, banded cells with shrunk surfaces. CM–HED process effectively reduced the free water content (FWC) and bound water content (BWC) but increased the portion of BWC in AS. The corresponding removal ratios of bound water and free water were 52.89% and 95.86% at the anode side and 46.28% and 92.75% at the cathode side, respectively. The coupling magnetic conditioning led to the largest BWC reduction of 23.14% in CM–HED process, and most of this reduction approaching 92.83% occurred during magnetic micro-particle conditioning stage. Gravity field caused the largest sludge reduction of 87.45%. During HED stage, the removal ratio of free water in AS was 63.73% at the anode side and 36.54% at the cathode side, while it was 21.9% and 10.96% for bound water, respectively. Along with water removed by CM–HED process, the organic matter in supernatant/filtrate increased, and a sharp rise occurred during HED stage. Meanwhile, the extracellular polymeric substance (EPS) contents initially decreased at MMPs–MF conditioning stage and then increased at the HED stage. Lower EPS contents in AS indicated better dewaterability. The largest reduction in the EPS content of AS at MMPs–MF conditioning stage corresponded to the largest decline in BWC. Furthermore, the protein-like substances in the supernatant/filtrate increased from 30% to 50%, whereas the fulvic acid-like and humic acid-like substances decreased from 54% to 27% at the HED stage. MMPs significantly reduced the polysaccharide and protein contents in the slime–EPS by 90.26% and 99.25%, respectively. Approximately 92.35% of humic acid-like materials in tightly bound EPS were reduced by MMPs. Thus, coupling magnetic conditioning should be selected as pretreatment prior to HED. [ABSTRACT FROM AUTHOR]

• Electronic polarization and defect engineering modification enhanced intrinsic PMS activation. • ACO-O V @PES membrane/PMS system achieved flow-through removal of contaminants. • The highly accessible SO 4 ·−, · OH, and 1O 2 were the responsible reactive species. • DFT calculations revealed PMS activation promotion by dual-modification strategy. The application of Fenton-like membrane reactors for water purification offers a promising solution to overcome technical challenges associated with catalyst recovery, reaction efficiency, and mass transfer typically encountered in heterogeneous batch reaction modes. This study presents a dual-modification strategy encompassing electron polarization and defect engineering to synthesize Al-doped and oxygen vacancies (O V)-enriched Co 3 O 4 spinel catalysts (ACO-O V). This modification empowered ACO-O V with exceptional performance in activating peroxymonosulfate (PMS) for the removal of organic contaminants. Moreover, the ACO-O V @polyethersulfone (PES) membrane/PMS system achieved organic contaminant removal through filtration (with a reaction kinetic constant of 0.085 ms−1), demonstrating outstanding resistance to environmental interference and high operational stability. Mechanistic investigations revealed that the exceptional catalytic performance of this Fenton-like membrane reactor stemmed from the enrichment of reactants, exposure of reactive sites, and enhanced mass transfer within the confined space, leading to a higher availability of reactive species. Theoretical calculations were conducted to validate the beneficial intrinsic effects of electron polarization, defect engineering, and the confined space within the membrane reactor on PMS activation and organic contaminant removal. Notably, the ACO-O V @PES membrane/PMS system not only mineralized the targeted organic contaminants but also effectively mitigated their potential environmental risks. Overall, this work underscores the significant potential of the dual-modification strategy in designing spinel catalysts and Fenton-like membrane reactors for efficient organic contaminant removal. [Display omitted] [ABSTRACT FROM AUTHOR]

A moderate Mn(Ⅶ) oxidation- in situ Fe(Ⅲ) coagulation (Mn(Ⅶ)-Fe(Ⅱ)) conditioning strategy was proposed to improve sludge filterability and release the water bound in extracellular polymeric substances (EPS). During Mn(Ⅶ)-Fe(Ⅱ) conditioning, flocs disintegration and cell disruption, macro and micro physicochemical properties of activated sludge, especially of EPS, were investigated. Relationships between protein molecular structures in EPS fractions of three layers and sludge dewaterability were also determined. Besides, factor analysis was used to explain the variances of "functional" protein secondary structures, which may have an important effect on sludge dewaterability. Results showed that sludge filterability (CST 0 /CST) increased by 2.40 times and partial bound water was released at 2 min oxidation of 120 mg/g KMnO 4 with subsequent FeCl 2 termination at equivalent molar ratio of 1:3. During this strategy, EPS wrapping on cells surface was disintegrated, and a limited influence occurred on cells. It was also found that CST and bound water content were strongly correlated with aggregated strands, random coil and β -turn percentages in slime (R 2 >−0.82, p < 0.05). Moreover, the dewaterability also presented strong negative correlations with aggregated strands, β -sheet and β -turn in TB-EPS (R 2 >−0.78, p < 0.05). This suggested that unfolding and despiralization of slime protein and moderate weakening rigidity of tightly bound EPS (TB-EPS) protein were beneficial for improvement of sludge dewaterability. In addition, the strong correlation between percentages of "functional" protein secondary structures and factor 1 score (R 2 > 0.85, p < 0.05) demonstrated that EPS migration, rather than only EPS disintegration, may have a key impact on the formation of some protein secondary structures in slime and TB-EPS. The observed protein secondary structures, which may affect sludge dewaterability, were probably derived from inner EPS. Graphical abstract Image 1 Highlights • CST 0 /CST reached 2.40 at a 2min Mn(Ⅶ) oxidation- in situ Fe(Ⅲ) coagulation. • Aggregated strands, random coil, β -turn in slime correlated with dewaterability. • Aggregated strands, β -sheet and β -turn in TB-EPS correlated with dewaterability. • Moderate weakening TB-EPS rigidity was beneficial for dewaterability improvement. • Aggregated strands, β -turn in slime and TB-EPS correlated with EPS migration. [ABSTRACT FROM AUTHOR]

In this study, La 3+ (ion)/La(OH) 3 -W/La(OH) 3 -EW-loaded magnetic cationic hydrogel (MCH) composites were fabricated in situ and characterized to investigate the effects of lanthanum species on phosphate adsorption. The corresponding maximum P adsorption capacities of MCH-loaded La 3+ (ion) (MCH-La 3+ (ion)), La(OH) 3 -W (MCH-La(OH) 3 -W), and La(OH) 3 -EW (MCH-La(OH) 3 -EW) were 70.5 ± 2.67, 69.2 ± 3.5, and 90.2 ± 2.9 mg P/g, respectively. Furthermore, for MCH-La(OH) 3 -EW, the P adsorption capacity was maintained relatively stable and high at pH 4.5–11 because of the ligand exchange, electrostatic interactions, and Lewis acid–base interactions. The enhanced adsorption of P was achieved over a wide pH range, as well as in the presence of competing anions (including Cl − , NO 3 − , SO 4 2− , HCO 3 − and SiO 4 4− ). Moreover, the exhausted MCH-La(OH) 3 -EW could be easily regenerated by a NaOH-NaCl desorption agent with above 72% adsorption capacity remained during five recycles. The column adsorption capacity of MCH-La(OH) 3 -EW reached ∼3500 bed volumes (BV) (∼67.7 mg P/g) as the concentration of P decreased from 5 mg/L to 0.1 mg/L. The ATR-IR, Raman, and XPS deconvolution results revealed that both MCH and lanthanum compounds, including La 3+ (ion), La(OH) 3 -W and La(OH) 3 -EW, contributed to the phosphate adsorption because of the electrostatic interactions between –N + (CH 3 ) 3 and phosphate, as well as the formation of LaPO 4 · x H 2 O. [ABSTRACT FROM AUTHOR]

• A novel synergistic technology coupling ultrasound and CNTs/PM (UCP) was developed. • Electron-rich organics could be rapidly removed in the UCP process from raw water. • RMnS oxidation and electron transfer were the main processes for CIP removal. • Ultrasound and CNTs played a critical role in promoting the generation of free RMnS. • CNTs could maintain satisfactory efficiency after repeated use in the UCP process. Recently, free reactive manganese species (RMnS) generated via permanganate catalytic oxidation technology has been applied to contaminants abatement and sludge dewatering. This study proposed a novel free RMnS generation method in ultrasound enhanced carbon nanotube (CNTs)/permanganate process (UCP) for organics removal. Taking ciprofloxacin as a target contaminant, the removal efficiency in the UCP process (9.78 s−1) was remarkably higher than that of the permanganate (0.71 s−1) and CNTs/permanganate (2.57 s−1) processes. CNTs could enrich manganese compounds and ciprofloxacin, and act as an electronic platform for the electronic transfer from ciprofloxacin to manganese compounds for free RMnS generation, which was revealed by DFT calculation and spectrum analysis. Meanwhile, ultrasound further regulated the generation of RMnS as it could transform the inactive solid Mn(IV) into free RMnS. In the UCP process, non-free radical modes including RMnS oxidation (49.8%) and electron transfer (23.5%) were the dominant processes for ciprofloxacin removal in the UCP process, and hydroxyl radical oxidation (13.2%), CNTs adsorption (5.5%), and PM oxidation (8.0%) also contributed to ciprofloxacin removal. Interestingly, CNTs could be well reused in the UCP process as more than 88.75% of ciprofloxacin was removed after five times reuse of CNTs. The UCP process provides a novel strategy for rapid contaminants removal in water treatment via continuous generation of free RMnS. [Display omitted] [ABSTRACT FROM AUTHOR]

• Electrolysis, permanganate, and O3 showed a satisfactory synergistic effect for various organics degradation. • Reactive manganese species (RMnS) and · OH were the dominant reactive species in E-PM-O3 process. • 1 mg L − 1 gaseous ozone dramatically promoted generating both RMnS and · OH with even lower energy consumption. • In situ formed MnO2 played a critical role for generating both RMnS and · OH. • · OH generated by O3 catalysis transfer colloid MnO2 to free mn (Ⅴ) and mn (Ⅵ) in the E-PM-O3 process. A novel water treatment process combining electrolysis, permanganate and ozone was tested in the laboratory. The combination showed synergistic effects in degrading various organic contaminants (like diclofenac, sulfamethoxazole, carbamazepine, etc.). A small amount of O 3 (1 mg L −1, 60 mL min−1) significantly improved the oxidation and mineralization ability of an electro-permanganate process by generating more reactive manganese species and hydroxyl radicals. The combination required less energy consumption than comparable processes. Mechanism experiments showed that the · OH involved was mainly generated by cathode reduction, homogeneous manganese catalysis, and heterogeneous manganese catalysis of O 3 decomposition. Reactive Mn species were generated by electro-reduction, · OH oxidation or/and O 3 activation. In situ generated Mn (Ⅳ) s plays a vital role in generating · OH and reactive Mn species. · OH generated by O 3 catalysis could transfer colloid Mn (Ⅳ) s to free Mn (Ⅴ) aq and Mn (Ⅵ) aq. And both the · OH and RMnS played the dominant role for DCF removal. Increasing permanganate dosage, O 3 concentration, the current density, C l − , or humic acid, and decreasing the pH all enhanced the degradation of diclofenac, but the presence of PO 4 3 − or HCO 3 − inhibited it. Supplementing electrolysis with permanganate and O 3 might be a practical, sustainable, and economical technology for treating refractory organics in natural waters. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The effective removal of organophosphorus compounds (OPs) effectively from water environment remains an important but challenging task. In this study, a resin-based nanocomposite of hydrated iron oxide (HD1) was used as Fenton-like catalyst for effectively catalyzing the decomposition of hydrogen peroxide to degrade tris(2-chloroethyl) phosphate (TCEP). The results showed that HD1 was successfully prepared, which had great versatility, catalytic performance and adsorption capacity. Besides, HD1/H 2 O 2 was capable of degrading TCEP completely with less than 0.2 mg/L of inorganic phosphorus (IP) in the effluent at the initial TCEP of 38 mg/L, pH = 4, H 2 O 2 dosage of 20 mM, and the K obs could result in about 1.0530 min−1 under identical conditions. More attractively, inorganic ions (i.e., Clˉ, CO 3 2ˉ, SO 4 2ˉ, NO 3 ˉ, HCO 3 ˉ, Ca2+, and Mg2+) exhibited moderate effect on TCEP degradation. The negative effect of natural organic matters (NOM) (i.e., HA) on the degradation of TCEP was responsible for competition for the active oxygen species. Combined with electron paramagnetic resonance (EPR) spectra, X-ray photoelectron spectroscopy (XPS) and other analytical methods and radical quenching experiments, the possible removal process of TCEP was discussed, including two processes of oxidative degradation and immobilization of IP. Besides, hydroxyl radicals (•OH) was the key active species that contributed to TCEP degradation through hydroxylation-oxidation and C–O bond cracking, and specificity adsorption of HFO on IP was revealed. Furthermore, the results showed that HD1 had desirable acid and alkali resistance. In the continuous running fixed bed column experiment, HD1 showed a satisfactory performance in cycle operations. This work proposed a new enhanced process for removing TCEP in water environment by HD1/H 2 O 2 , and the multi-functional material, HD1 was promising in treatment of water containing organic phosphorus pollutants. This will be believed that this study will provide new ideas and new materials for the treatment of organic phosphorus-based organic pollutants, and lay the foundation for further deepening and expanding the application of adsorption resins in the field of water pollution control. Image 1 • TCEP degradation efficiency reached 95.5% with residual inorganic phosphate less than 0.2 mg/L. • TCEP and its degradation products were removed simultaneously in one step. • The mechanism of the TCEP purification and inorganic phosphate removal was illustrated. • Hydroxylation and C–Cl bond cleavage were involved in the TCEP degradation paths. • The HD1 could be readily regenerated for continuous runs. [ABSTRACT FROM AUTHOR]

Electrolysis and permanganate (PM) oxidation are two commonly used technologies for water treatment. However, they are often handicapped by their slow reaction rates. To improve the removal efficiency of refractory contaminants, we combined electrolysis with PM using an activated carbon fiber (ACF) as cathode (E-ACF-PM) for the first time to treat diclofenac (DCF) in aqueous solution. Up to 90% DCF was removed in 5 min by E-ACF-PM process. In comparison, only 3.95 and 27.35% of DCF was removed by individual electrolysis and PM oxidation at the same time, respectively. Acidic condition was more conducive to DCF removal. Surprisingly, soluble Mn(III) (aq) formed on the surface of ACF was demonstrated as the principal oxidizing agent in E-ACF-PM process. Further studies showed that all three components (electrolysis + ACF + PM) were necessary to facilitate the heterogeneous generation of reactive Mn(III) (aq). Moreover, SEM images and XPS spectra of ACF before and after treatment revealed that the morphologies and elemental compositions of reacted ACF were nearly unchanged during the E-ACF-PM process. ACF can be remained active and utilized to the rapid degradation of DCF in E-ACF-PM process even after reused for 20 times. Therefore, the E-ACF-PM process may provide a novel and effective alternative on the generation of reactive Mn(III) (aq) in situ for water treatment by green electrochemical reactions. Image 1 • A novel synergistic technology coupling electrolysis and permanganate (PM) was developed. • DCF can be rapidly removed in E-ACF-PM process from raw water. • Mn(III) formed on the ACF cathode played a key role in DCF degradation. • All three components (electrolysis + ACF + PM) were necessary to facilitate the heterogeneous generation of reactive Mn(III). • The recycled ACF for 20 times in E-ACF-PM process still had a satisfactory efficiency. [ABSTRACT FROM AUTHOR]