Hematite, a predominant iron oxide in tropical and subtropical soils and sediments, plays a pivotal role in regulating the biogeochemical cycling of contaminants and nutrients. Its reactivity varies substantially with crystallographic facets; however, the facet-dependent mechanisms underlying sulfidation, a representative surface-mediated process in anaerobic settings (e.g., paddy fields, mangroves, and tidal flats), remain poorly understood. Here, we synthesized hematite nanoparticles with dominant (001), (110), and (214) faces (denoted HNP, HNR, and HBI) and probed their sulfidation pathways under anoxic conditions. Combining aqueous chemistry with surface/bulk characterization, we show that despite identical final sulfidation products, the underlying mechanisms differ markedly among facets. HNP consumed dissolved S(-II) 14-19 times faster than HNR and HBI, due to its undulating and rugged morphology and a higher free-corrosion potential that provides abundant reactive hydroxyl sites and promotes electron uptake. In contrast, HNR and HBI show rapid initial pyrite formation via the ferric-hydroxide-surface (FHS) pathway but suffer from passivation by dense FeSx layers, limiting long-term conversion. HNP sustains reactivity through continuous ferrihydrite regeneration and the absence of a passivation layer, achieving the highest overall hematite conversion (similar to 63% vs. similar to 41%-42%) and pyrite production (similar to 24% vs. similar to 18%-21%). These findings challenge the simplistic view that high-energy facets always dominate reactivity, highlighting instead the importance of defect-mediated surface chemistry and longterm sustainability. This study has implications for importance in predicting iron-sulfur interactions and the bioavailability and mobility of associated elements in redox-fluctuating environments.

Iron sulfide (FeS) nanoparticles demonstrate great potential for degrading organic contaminants under aerobic conditions through the production of hydroxyl radicals (center dot OH). However, its oxidative efficacy is often constrained by low electron utilization efficiency. In this study, we developed a polyacrylic acid (PAA)-mediated FeS oxidation system and investigated its effectiveness in sulfamethoxazole (SMX) degradation. The results indicate that PAA substantially enhanced the degradation of SMX by FeS at oxic conditions. As PAA dosage increased from 0.1 to 0.4 g/L, the observed degradation rate constants (kobs) of SMX were enhanced by 3- to 10-fold. Quenching experiments identified center dot OH as the primary reactive species responsible for SMX degradation. The electron utilization efficiency of FeS for center dot OH production was significantly increased from 0.3 % in FeS-only system to 2.1 % upon the addition of 0.4 g/L PAA. The enhancement was primarily attributed to the formation of dissolved Fe(II)-PAA complexes and the promotion of Fe redox cycling by PAA. By combining intermediate identification with density functional theory calculations, the degradation pathway of SMX was elucidated thoroughly. Additionally, the FeS/PAA/O2 system exhibited exceptional degradation efficiency toward other common organic pollutants. X-ray diffraction and transmission electron microscopy revealed that PAA inhibited the formation of crystalline gamma-FeOOH during FeS oxidation, which instead leads to the generation of amorphous structures. Collectively, this study provides fundamental insights into the oxidizing performance of FeS/PAA system and proposes a promising remediation technique for removing sulfonamide antibiotics.

Chain elongation (CE) offers a promising route for valorizing organic waste streams into medium-chain carboxylic acids (MCCA), but biomass washout at short hydraulic retention times (HRTs) constrains continuous CE process. Two parallel continuous lactic acid (LA) based CE bioreactors were operated to assess whether polyurethane foam (PUF) could retain biomass and support process performance: R1 with PUF and R2 without PUF as control. During longest paired steady-state period at a 2-day HRT, R1 maintained lower residual LA and a caproic acid (CA) concentration of 50.27±3.60mmol/L, compared with 46.84±4.76mmol/L in R2. PUF addition enhanced CE process robustness, enabling faster recovery after HRT reduction and organic shock loading. Subsequent in-situ and ex-situ batch assays indicated a 50% higher apparent volumetric CA production rate in R1 than in R2. Difference-based estimates suggested that PUF-associated biomass accounted for ~66% of LA consumption and ~69% of butyric acid (BA) production in R1, whereas suspended fraction accounted for ~61% of CA production under the assay conditions. Microbial community analysis revealed that PUF-biofilm contained a higher relative abundance of Clostridium sensu stricto 12 and a lower relative abundance of Caproiciproducens than the suspended samples. These genus-level patterns were highly associated with the compartment-level product-rate differences between PUF attached and suspended biomass observed in PUF amended reactor. These findings not only highlight potential of PUF-assisted strategies to enhance biomass retention and operational robustness in continuous CE bioreactors, but also reveal important role of PUF in shaping the spatially structured CE microbiome across attached and suspended compartments.

Oxygenation of mackinawite (FeS) at redox interfaces constitutes a key biogeochemical process that generates hydroxyl radicals (•OH) and facilitates contaminant attenuation. However, the influence of common inorganic ligands such as tripolyphosphate (TPP) on interfacial electron transfer in this process remains poorly understood. Herein, 1.0 mM TPP increased cumulative •OH production approximately 23.5-fold over 180 min of FeS oxygenation, with the electron utilization efficiency for •OH production increasing from 0.33% to 8.18%. TPP enhanced •OH generation by promoting Fe(II) dissolution, thereby driving homogeneous Fenton-like reactions, while facilitating Fe(III)/Fe(II) redox cycling through solid-liquid interactions. Additionally, TPP acted as an interfacial coordination modulator by rearranging the local Fe(II) environment, and the resulting surface Fe(II)-TPP complexes improved the utilization of structural electrons. Electrochemical measurements and DFT calculations indicated that this interfacial coordination suppressed structural Fe(II) oxidation and reduced unproductive electron consumption, while lowering the energy barrier for H2O2-forming O2 activation at TPP-modified FeS sites. XRD, FTIR, and EXAFS analyses showed that TPP adsorption inhibited lepidocrocite crystallization and redirected secondary mineral evolution toward ferrihydrite-rich products. These findings elucidate how ubiquitous ligands regulate mineral-water interfacial processes and •OH generation, providing a basis for optimizing FeS-based environmental remediation technologies.

Sulfidated nanoscale zerovalent iron (S-nZVI) is a promising material for the remediation of chlorinated hydrocarbons (CHCs) in groundwater, offering enhanced reactivity and selectivity over unmodified nanoscale zerovalent iron (nZVI). However, integrating S-nZVI with bioremediation using organohalide-respiring bacteria (OHRB) poses potential cytotoxicity challenges. This study investigated the differential impacts of S-nZVI and nZVI on the dechlorination activity of Dehalococcoides mccartyi strain 195 (Dhc 195), a representative OHRB. Key factors, including hydrogen evolution reaction (HER), pH, Fe2+ concentration, and nanoparticle-cell interactions, were assessed. S-nZVI exhibited significantly lower cytotoxicity compared to nZVI, primarily due to the reduced nanoparticle adhesion to Dhc 195 cell membranes, attributed to its negative surface charge rather than to the milder physicochemical disturbances in the culture medium. S-nZVI minimally disrupted extracellular polymeric substances (EPS), preserving cell integrity, and provided a more sustained hydrogen supply under hydrogen-limited conditions. Limited contact experiments confirmed that the reduced cytotoxicity of S-nZVI stemmed from lower contact toxicity rather than its intrinsic chemical reactivity. This study unveils the mechanisms underlying the interaction between S-nZVI and OHRB, highlighting S-nZVI's potential for safer and more effective abiotic-biotic remediation strategies. The findings provide a scientific basis for optimizing combined remediation approaches for comprehensive CHCs cleanup.

Fe( ii )-catalyzed ferrihydrite transformation enhances sequestration of pre-adsorbed Pb/Cr through isomorphous substitution or stable phase formation.

Three parallel sequencing batch reactors (control, small-sized polyurethane sponge (PUS) (3.0 mm), and large-sized PUS (10.0 mm)) were used to investigate aerobic granular biofilm (AGB) characteristics. Results show that 10.0 mm PUS facilitated rapid formation of large-sized AGB (AGBL), which exhibited higher biomass concentration (8.5 g/L) and faster settling velocity (69.2-159.3 m/h) than aerobic granular sludge (AGS) (3.2 g/L and 38.6-80.0 m/h). The AGBL system also maintained long-term structural stability with a lower instability coefficient (0.004-0.018 min-1) than AGS (0.053-0.090 min-1). Additionally, during long-term operation, the AGBL system achieved excellent removal efficiencies for NH4+-N (99.6 ± 0.4 %) and total nitrogen (92.3 ± 2.6 %), and exhibited a lower sludge yield (0.05 gVSS/gCOD) than AGS (0.14 gVSS/gCOD). The larger size and compact structure of AGBL increased anoxic/anaerobic zones, enriching denitrifying and hydrolytic/fermentative bacteria. These findings highlight AGBL with large PUS as a more promising biotechnology for practical applications than conventional AGS.

Thiamine (vitamin B-1) and its precursor 2-methyl-4-amino-5-hydroxymethylpyrimidine (HMP) have been shown to exert an important influence on primary production in marine environments, but little is known about their influence in fresh waters. We evaluated the ecological effects of thiamine and one of its precursors HMP in streams within the Qiyun catchment, a headwater mountain system of a Yangtze River tributary in Southern China, using nutrient-diffusing substrates. Thiamine limitation of periphyton was observed in April 2019, and HMP limitation was observed in both April and May 2019. Co-limitation by thiamine plus phosphorus and by HMP plus nitrogen occurred in May. The effect sizes of thiamine and HMP on growth of periphyton were similar to each other. Physiochemical features of the stream showed different potential influences on the effects of thiamine and HMP. Water temperature was negatively associated with the effect of thiamine, whereas ammonium showed a negative relationship with the effect of HMP. These findings extend our knowledge of nutrient limitation by thiamine and one thiamine precursor in freshwater environments.

Biogenic sulfidation of zero-valent iron (ZVI) using sulfate reducing bacteria (SRB) has shown enhanced dechlorination rates comparable to those produced by chemical sulfidation. However, controlling and sustaining biogenic sulfidation to enhance in situ dechlorination are poorly understood. Detailed interactions between SRB and ZVI were examined for 4 months in column experiments under enhanced biogenic sulfidation conditions. SRB proliferation and changes in ZVI surface properties were characterized along the flow paths. The results show that ZVI can stimulate SRB activity by removing excessive free sulfide (S2-), in addition to lowering reduction potential. ZVI also hinders downgradient movement of SRB via electrostatic repulsion, restricting SRB presence near the upgradient interface. Dissolved organic carbon (e.g., >2.2 mM) was essential for intense biogenic sulfidation in ZVI columns. The presence of SRB in the upgradient zone appeared to promote the formation of iron polysulfides. Biogenic FeSx deposition increased the S content on ZVI surfaces ∼3-fold, corresponding to 3-fold and 2-fold improvements in the trichloroethylene degradation rate and electron efficiency in batch tests. Elucidation of SRB and ZVI interactions enhances sustained sulfidation in ZVI permeable reactive barrier.

Recent observations in marine ecosystems show that the presence of thiamine regulates primary production, but little is known about the ecological effect of thiamine in streams. We conducted nutrient enrichment experiments in four streams in the New York's Adirondack Mountains using nutrient diffusing substrates to evaluate the influence of thiamine (vitamin B-1) on the growth of stream periphyton. Contrasting treatments in our study included nutrient additions of thiamine (C12H17ClN4OS center dot HCl), nitrogen (NH4Cl), and phosphorus (NaH2PO4). Thiamine limitation occurred in 12 of 14 experiments conducted from June through October in 2015-2017, nitrogen limitation occurred in eight experiments, and phosphorus limitation in one experiment. The magnitude of response of periphyton to thiamine enrichment varied among seasons, years, and streams. The growth-enhancing effect on periphyton biomass from thiamine or nitrogen addition typically occurred between 8 and 32 d of incubation, though the periphyton accumulation rate declined after 16-24 d of incubation. Our results showed that thiamine is a limiting nutrient for primary producers in our study streams and its effect size is similar to that of nitrogen. These findings extend the prior recognition of thiamine's substantial influence on marine photosynthetic eukaryotes to having a similar role in freshwater ecosystems.

Bacteria can use nitrate as a nutrient for growth, but the underlying mechanisms of this pathway have not yet been identified. We investigated the effects of changing the nitrogen source from ammonia to nitrate on the properties of heterotrophic bacterial growth in anoxic and anoxic/oxic (A/O) SBRs. Both SBR types were seeded with activated sludge cultivated with ammonia and were then fed with 1,400 mg.L-1 chemical oxygen demand (COD) and 250 mg.L-1 of nitrate nitrogen. Heterotrophic bacteria had a lag period of 8-9 d and 13-14 d in terms of growth and COD and nitrogen removal, respectively, in both reactors with nitrate as nutrient. Of the influent nitrate, 15% were converted to biomass nitrogen. Compared with ammonia or organic nitrogen as a nutrient source, with the use of nitrate more energy was needed for proteins synthesis, which resulted in a lower sludge yield (0.32-0.35) and lower amounts of proteins and phosphorus compounds. Furthermore, fewer extracellular polymer substances (EPS) and more soluble microbial products (SMP) were produced, both of which also had low proteins and high polysaccharide contents. The proteins in the cells were synthesized via dissimilatory nitrate reduction to ammonia (DNRA).

Granules initiation and development is the backbone of aerobic granular sludge technology. Feed composition can notably affect initiation and development of aerobic granules, and yield aerobic granules with distinct microbial community, morphology and structure. This paper reports an unexpected formation of aerobic granules in an aspartic acid fed SBR under unfavorable hydrodynamic selection conditions. Detailed characteristics of these aerobic granules were investigated in terms of morphology, structure, bioactivity and EPS. The results showed that due to the absence of favorable hydrodynamic selection pressure, the formed aerobic granules had an irregular shape with a rough outline and loose internal structure, which was quite different from mature aerobic granules. Bacteria in these aerobic granules were mainly presented in the form of microcolony with calcium and β-polysaccharides responsible for its mechanical stability. The high N/C ratio of aspartic acid enabled the enrichment of significant amount of nitrifiers within aerobic granules and thus resulted in high nitrification activity of these aerobic granules. The negatively charged and hydrophilic aspartic acid also induced the bacteria to secrete more exopolysaccharides for contributing to more neutral and hydrophilic surface of the aerobic granules, which was beneficial for aspartic acid capture. As a result, polysaccharides, rather than proteins, became the major components of EPS in these aerobic granules. This paper provides us a foundation to better understand the granulation potential of proteinaceous substrates that is frequently encountered in industrial wastewaters.

Although EPS in microbial aggregates are importance in successful implementation of biological wastewater treatment systems, they also exhibit detrimental role on certain circumstance, such as excess sludge dewatering. Extensive efforts have been put into the disruption of EPS for improving the dewaterability of excess sludge and Fenton's reagent treatment has been demonstrated to be a very promising sludge conditioning method for EPS destruction. However, the information regarding detailed degradation process of EPS during Fenton's reagent treatment is limited. In this study, EPS were extracted from activated sludge and treated with different concentrations of Fenton's reagent. The physicochemical characteristic changes of EPS under different treatment were investigated in terms of components, EEM, molecular weight (MW), UV-Vis and FTIR. The results showed that EPS were prone to be disintegrated, but hard to be fully mineralized. Humic substances in EPS were more resistant to Fenton's reagent than other components. Low MW components of EPS were preferentially degraded prior to the disruption of high MW components. Besides, the disintegration of EPS into lower MW ones was accompanied by the formation of higher MW compounds caused by the bridge interaction of Fe ions. The cleavage of protein's backbone in EPS was mainly through destruction of amide II (N–H and C–N) in –CO–NH–. Fenton's reagent treatment also led to a significant increase of oxygen-containing functional groups in EPS molecules. This paper may pave a path to deeply understand the mechanisms of dewatering improvements of excess sludge by Fenton's conditioning.

The feasibility of rapidly controlling activated sludge bulking and accelerating aerobic sludge granulation was evaluated by adding intact aerobic granular sludge (AGS) to the bulking activated sludge (BAS) reactor. Two ratios of AGS to BAS (0.2 in the first reactor (R1), and 0.4 in the second reactor (R2)) were tested. The results indicate that the addition of AGS immediately improved the settling ability of BAS (sludge volume index at 30 min (SVI30) in R1 and R2 decreased from 173.1 mL/g to 130.8 and 91.3 mL/g, respectively) and gradually increased the biomass concentration (mixed liquor suspended solids (MLSS) in R1 and R2 increased to 4722 and 5190 mg/L, respectively), thus resolving the sludge bulking problem. Meanwhile, adding AGS not only promoted the BAS growth in aggregates, but also facilitated the selection of well-settling aggregates at an early stage. Consequently, the granulation process was significantly accelerated. The granulation time in R1 and R2 was 14 and 10 days, respectively, indicating that the higher ratio of AGS to BAS can result in the faster granulation. Partial nitrification could be maintained during the BAS granulation process when the initial inoculation of nitritation sludge was large enough. Additionally, the microbial community changed during the BAS granulation process. The genera Thauera and Zoogloea belonging to family Rhodobacteraceae were speculated to play an important role in the BAS granulation.

Characteristics of extracellular polymeric substances (EPS) in activated sludge strongly depend on wastewater substrates. Proteinaceous substrates (ProS) present in heterogeneous polymeric form are intrinsic and important parts of wastewater substrates for microorganisms in activated sludge systems. However, correlations between ProS and characteristics of EPS are scarce. This study systematically explored the impacts of monomeric (Mono-), low polymeric (LoP-) and high polymeric (HiP-) ProS on compositions and functional groups of EPS in activated sludge. The results showed that the change of polymerization degree of ProS significantly altered the composition of EPS. Compared to EPSMono-ProS, the proportion of proteins in EPSLoP-ProS and EPSHiP-ProS increased by 12.8% and 27.7%, respectively, while that of polysaccharides decreased by 22.9% and 63.6%, respectively. Moreover, the proportion of humic compounds in EPSLoP-ProS and EPSHiP-ProS were ∼6 and ∼16–fold higher than that in EPSMono-ProS, respectively. The accumulation of humic compounds in EPS increased the unsaturation degree of EPS molecules, and thereby reduced the energy requirement for electrons transition of amide bonds and aromatic groups. Size exclusion chromatography (SEC) analyses detected more molecular clusters in EPSHiP-ProS, indicating more complex composition of EPS in HiP-ProS fed activated sludge. Spectroscopic characterization revealed the dominance of hydrocarbon, protein, polysaccharide and aromatic associated bonds in all three EPS. Nevertheless, with the increase of polymerization degree of ProS, the protein associated bonds (such as CONH, CO, NC, NH) increased, while the polysaccharide associated bonds (such as COC, COH, OCOH) decreased. This paper paves a path to understand the role of ProS in affecting the production and characteristics of EPS in biological wastewater treatment systems.

An anaerobic sequencing batch reactor(ASBR) inoculated with activated sludge was employed to investigate the start-up of anaerobic ammonium oxidation(ANAMMOX) process and the spatial distribution of extracellular polymeric substances(EPS) in ANAMMOX granules. The results showed that the removal rates of NH4+-N and NO2--N reached more than 99%. The removal rate of total nitrogen(TN) was 89.87%±0.43% and the TN removal load in the ASBR was 1.7 kg·(m3·d)-1. The ratios of nitrite consumption and nitrate production to ammonium consumption were 1.32±0.08 and 0.24±0.03, respectively. Besides, the pH and the effluent nitrate concentration in bulk liquid were considered as two simple indicators for rapid diagnosis of ANAMMOX performance. The proteins(PN) was the main component of EPS in ANAMMOX granular sludge. The PN and polysaccharides(PS) in ANAMMOX granules were (59.61±5.64) mg·g-1 and (12.21±2.04) mg·g-1, respectively, with the ratio of PN/PS reaching approximately 4.88±1.39. β-D-glucofuranose and dead cells were distributed in the outermost layer of granules, while living cells, PN, lipids, α-glucosamine and α-mannose were distributed throughout the granules and mainly concentrated on the outside of granules. PN and lipids constituted the framework of ANAMMOX granules and ANAMMOX bacteria were embedded among the PN and lipids matrix.

Different from monomeric substrate, polymeric substrate (PS) needs to undergo slow hydrolysis process before becoming available for consumption by bacteria. Hydrolysis products will be available for the heterotrophs in low concentration, which will reduce competitive advantages of heterotrophs to nitrifiers in mixed culture. Therefore, some links between PS and nitrification process can be expected. In this study, three lab-scale sequencing batch reactors with different PS/total substrate (TS) ratio (0, 0.5 or 1) in influent were performed in parallel to investigate the influence of PS on nitrification process in activated sludge system. The results showed that with the increase of PS/TS ratio, apparent sludge yields decreased, while NO3--N concentration in effluent increased. The change of PS/TS ratio in influent also altered the cycle behaviors of activated sludge. With the increase of PS/TS ratio from 0 to 0.5 and 1, the ammonium and nitrite utilization rate increased ∼2 and 3 times, respectively. The q-PCR results showed that the abundance of nitrifiers in activated sludge for PS/TS ratio of 0.5 and 1 were 0.7-0.8 and 1.4-1.5 orders of magnitude higher than that for PS/TS ratio of 0. However, the abundance of total bacteria decreased about 0.5 orders of magnitude from the former two to the latter. The FISH observation confirmed that the nitrifiers' microcolony became bigger and more robust with the increase of PS/TS ratio. This paper paves a path to understand the role of PS/TS in affecting the nitrification process in biological wastewater treatment systems.

In water treatment processes that involve contaminant reduction by zerovalent iron (ZVI), reduction of water to dihydrogen is a competing reaction that must be minimized to maximize the efficiency of electron utilization from the ZVI. Sulfidation has recently been shown to decrease H2 formation significantly, such that the overall electron efficiency of (or selectivity for) contaminant reduction can be greatly increased. To date, this work has focused on nanoscale ZVI (nZVI) and solution-phase sulfidation agents (e.g., bisulfide, dithionite or thiosulfate), both of which pose challenges for up-scaling the production of sulfidated ZVI for field applications. To overcome these challenges, we developed a process for sulfidation of microscale ZVI by ball milling ZVI with elemental sulfur. The resulting material (S-mZVIbm) exhibits reduced aggregation, relatively homogeneous distribution of Fe and S throughout the particle (not core-shell structure), enhanced reactivity with trichloroethylene (TCE), less H2 formation, and therefore greatly improved electron efficiency of TCE dechlorination (εe). Under ZVI-limited conditions (initial Fe0/TCE = 1.6 mol/mol), S-mZVIbm gave surface-area normalized reduction rate constants (k'SA) and εe that were ∼2- and 10-fold greater than the unsulfidated ball-milled control (mZVIbm). Under TCE-limited conditions (initial Fe0/TCE = 2000 mol/mol), sulfidation increased kSA and εe ≈ 5- and 50-fold, respectively. The major products from TCE degradation by S-mZVIbm were acetylene, ethene, and ethane, which is consistent with dechlorination by β-elimination, as is typical of ZVI, iron oxides, and/or sulfides. However, electrochemical characterization shows that the sulfidated material has redox properties intermediate between ZVI and Fe3O4, mostly likely significant coverage of the surface with FeS.

A novel metal foam-based Fenton-like process for wastewater treatment is illustrated in this study. In the system, H2O2 was generated in situ by taking advantage of O2 in air, as metal could activate dissolved O2 to produce •O2- and then generate H2O2. Furthermore, metal foam can enhance the Fe3+/Fe2+ cycling, which eventually improved the efficiency of the Fenton process. The performance of the novel Fenton-like process was assessed by methyl blue (MB), and 94% MB removal could be achieved within 5 min in nickel (Ni) foam system. The degradation of MB in this study was based on both •OH and •O2- radicals, where •O2- radical served as the precursor to generate •OH for MB degradation through a Fenton process. The pH value of 3 with the initial Fe2+ concentration of 0.25 mM was found to be the optimum condition for the Fenton-like process. This study provides a general and new strategy for efficient wastewater treatment just using aeration and metal foams (such as Ni, Al, and Cu foams), which also offers a good alternative for rational design and application of traditional Fenton process.

A novel composite material MgO-biochar (MgO-BC) with the peanut shells as the precursors was successfully fabricated by loading magnesium oxide (MgO) on the surface of biochar (BC) at high temperature and in oxygen-limited atmosphere. The adsorption characteristics of the resultant adsorbent toward phosphate from aqueous solution were investigated by evaluating the influences of pH, contact time and coexisting ions. The results showed that the best phosphate adsorption onto MgO-BC happened in the pH range of 7-9, and strong acidic or basic media was unfavorable to the phosphate adsorption. Phosphate adsorption process could reach equilibrium within 540 min, and the kinetics curve could be well fitted by both pseudo-first and pseudo-second models. The related coefficients were 97.3% and 99.0%. MgO-BC exhibited highly selective capacity toward phosphate in the presence of competing Cl-, HCO3- and NO3- at 10 times higher concentration than the phosphate concentration. In addition, phosphate adsorption onto MgO-BC could be described satisfactorily by Langmuir model with a fitting coefficient of higher than 99%, and the maximal adsorption capacity calculated by Langmuir equation was 138.07 mg·g-1. The adsorption capacity of phosphate by MgO-BC was much higher than the unmodified BC and other biochar-based sorbents. Furthermore, the composite material after the adsorption of phosphate could also be used as a fertilizer into the soil. It achieved the reuse of the discarded phosphate. All the results validated that MgO-BC has a wide application prospect for the phosphate cleanup from the actual wastewater.