Attenuation of phenanthrene and pyrene adsorption by sewage sludge-derived biochar in biochar-amended soils

Remediation of polycyclic aromatic hydrocarbons polluted soil by biochar loaded humic acid activating persulfate: performance, process and mechanisms

The remediation for polycyclic aromatic hydrocarbons contaminated soil with cost-effective method has received significant public concern, a composite material, therefore, been fabricated by loading humic acid into biochar in this study to activate persulfate for naphthalene, pyrene and benzo(a)pyrene remediation. Experimental results proved the hypothesis that biochar loaded humic acid combined both advantages of individual materials in polycyclic aromatic hydrocarbons adsorption and persulfate activation, achieved synergistic performance in naphthalene, pyrene and benzo(a)pyrene removal from aqueous solution with efficiency reached at 98.2%, 99.3% and 90.1%, respectively. In addition, degradation played a crucial role in polycyclic aromatic hydrocarbons remediation, converting polycyclic aromatic hydrocarbons into less toxic intermediates through radicals of ·SO4-, ·OH, ·O2-, and 1O2 generated from persulfate activation process. Despite pH fluctuation and interfering ions inhibited remediation efficiency in some extent, the excellent performances of composite material in two field soil samples (76.7% and 91.9%) highlighted its potential in large-scale remediation.

Predicting the speciation of ionizable antibiotic ciprofloxacin by biochars with varying carbonization degrees†

Sorption mechanisms of ionizable organic pollutants by biochars and approaches for the prediction of sorption are still unclear. In this study, batch experiments were conducted to explore the sorption mechanisms of woodchip-derived biochars prepared at 200–700 °C (referred as WC200–WC700) for cationic, zwitterionic and anionic species of ciprofloxacin (referred as CIP⁺, CIP^± and CIP⁻, respectively). The results revealed that the sorption affinity of WC200 for different CIP species was in the order of CIP^± > CIP⁺ > CIP⁻, while that of WC300–WC700 remained the order of CIP⁺ > CIP^± > CIP⁻. WC200 exhibited a strong sorption ability, which could be attributed to hydrogen bonding and electrostatic attraction with CIP⁺, electrostatic attraction with CIP^±, and charge-assisted hydrogen bonding with CIP⁻. Pore filling and π–π interactions contributed to the sorption of WC300–WC700 for CIP⁺, CIP^± and CIP⁻. Rising temperature facilitated CIP sorption to WC400 as verified by site energy distribution analysis. Proposed models including the proportion of the three CIP species and sorbent aromaticity index (H/C) can quantitatively predict CIP sorption to biochars with varying carbonization degrees. These findings are vital to elucidating the sorption behaviors of ionizable antibiotics to biochars and exploring potential sorbents for environmental remediation.

This study revealed the evolution of sorption mechanisms with pyrolysis temperature of biochar and CIP speciation, and provided a novel approach for the sorption prediction of ionizable antibiotics.

Phosphate sequestration by lanthanum-layered rare earth hydroxides through multiple mechanisms while avoiding the attenuation effect from sediment particles in lake water

Lanthanum-based adsorbents have been used extensively to capture phosphate from wastewater. However, the attenuation effect that arises from the coexistence of sediment and humic acid is the major drawback in practical applications. The Lanthanum-layered rare earth hydroxides (LRHs)-Cl (La-LRH-Cl) was synthesized and achieved high elemental phosphorus (P) adsorption capacity (138.9 mg-P g^-1) along with a fast adsorption rate (k₂ = 0.0031 g mg^-1·min^-1) over a wide pH range while avoiding the attenuation effect that arises from the coexistence of sediment and humic acid in lake water. The La-LRH-Cl effectively captured phosphate through multiple interactions, such as the ion exchange of Cl^- and phosphate, the memory effect of LRH and the inner-sphere complexation of La-P. Moreover, physical models demonstrated that the adsorption of phosphate onto La-LRH-Cl was a monolayer endothermic process, during which PO₄^3- interacted by multi-docking via parallel orientation at 293 K and multi-ionic interactions through pure non-parallel orientation at 303 K. Hence, 1000 L of 11.08 mg-P L^-1 of the acquired lake water was decontaminated by 30 g of La-LRH-Cl to 0.09 mg-P L^-1 within 7 days. In addition, over ~12,125 BV of an industrial effluent containing 3.26 mg-P L^-1 was treated to below USEPA's discharge limit in fixed-bed tests. It was found that the memory effect of LRH was responsible for the stable performance and reusability. Therefore, more focus should be placed on the collective role of La and LRH layered structure as a means of preventing the attenuation effect in the real water matrix.

Effect of Ca2+ ions on naphthalene adsorption/desorption onto calcium oxide nanoparticle: Adsorption isotherm, kinetics and regeneration studies

The adsorptive nature of calcium oxide nanoparticles in aqueous sample of naphthalene in presence of Ca²⁺ ions was estimated. Enhanced efficiency of calcium oxide regeneration (90%) with the aid of calcium chloride in the solution concentration of 0.002-0.1 M was depicted. The less degree of toxic naphthalene desorption merged with SEM, FTIR and XRD characterization data portrays the importance of naphthalene adsorption onto calcium oxide using calcium chloride for regeneration. Batch adsorption studies were performed to evaluate the operating parameters such as pH, naphthalene concentration, contact time and impact of Ca²⁺ on naphthalene study. The adsorption isotherm of naphthalene on calcium oxide nanoparticle was described by Langmuir, Freundlich, Temkin and Dubinin Radushkevich and theoretical maximum monolayer adsorption capacity was found to be 63.81 mg/g at 303 K. The adsorption kinetic best fitted with pseudo second order kinetic model. The positive influence of making the addition of Ca²⁺ ions into naphthalene solution for its rapid adsorption was elucidated which is leaded by a probable increase in sorption capacity for naphthalene molecules at lower concentrations. The stable nature of crystallinity of calcium oxide and a less degree of naphthalene molecules leaching during consecutive cycles of adsorptive process and nanoparticle regeneration was also scrutinized.

Pretreatment, modification and applications of sewage sludge-derived biochar for resource recovery- A review

With the quick increase in industrialization and urbanization, a mass of sludge has been produced on the account of increased wastewater treatment facilities. Sewage sludge (SS) management has become one of the most crucial environmental problems because of the existence of various pollutants. However, SS is a carbon-rich material, which has favored novel technologies for biochar production, which can be utilized for dissimilar applications. This review systematically analyzes and summarizes the pretreatment, modification, and especially application of sewage sludge-derived biochar (SSBC), based on published literature. The comparative assessment of pretreatment technology such as pyrolysis, hydrothermal carbonization, combustion, deashing, and co-feeding is presented to appraise their appropriateness for SS resource availability and the production of SSBC. In addition, the authors summarize and analyze the current modification methods and divide them into two categories: physical properties and surface chemical modifications. The applications of SSBC as absorbent, catalyst and catalyst support, electrode materials, gas storage, soil amendment, and sold biofuel are reviewed in detail. Furthermore, the discussion about the existing problems and the direction of future efforts are presented at the end of each section to envisage SS as a promising opportunity for resources rather than a nuisance.

Polycyclic aromatic hydrocarbons (PAHs) persistence, bioavailability and toxicity in sewage sludge- or sewage sludge-derived biochar-amended soil

Soils can be contaminated with polycyclic aromatic hydrocarbons (PAHs) when either sewage sludge (SSL) or biochar (BC) are used. There are no comparative studies regarding the effects of soil amendment with SSL or BC on the persistence, bioavailability and toxicity of PAHs. This research compared the persistence of PAHs (based on the extractable content, C_tot) and their bioavailability (freely dissolved, C_free) as well as the toxicity (solid phase: Phytotoxkit F with Lepidium sativum and the Collembolan test with Folsomia candida; leachates: Phytotestkit F with L. sativum and Microtox® with Aliivibrio fischeri) of soil amended with SSL or with SSL-derived BCs. BCs were produced from three different sewage sludges at a temperature of 500 °C. SSLs or BCs were added to the soil at a rate of 1% (30 t/ha). Adding SSL to the soil increased more the PAH content in it than after BC application, which was associated with a higher content of PAHs in SSL. Losses of Σ16 C_tot and C_free PAHs were higher than those observed for biochar only in the case of one SSL. In the other cases, PAH losses were either higher for biochar or did not differ significantly between SSL and BC. On the other hand, the analysis of the individual groups of PAHs showed significant differences between SSL and BC, both for C_tot and C_free. Nonetheless, these differences were largely driven by the type of sewage sludge and biochar. Only in the case of root growth inhibition the toxicity higher was for the SSL-amended soils than for the BC-amended ones. In the other cases, varying results were observed which were determined by the type of sewage sludge/biochar, similarly to PAH losses.

Co-pyrolysis of sewage sludge and biomass in carbon dioxide as a carrier gas affects the total and leachable metals in biochars

The total and available (water extracted) content of selected metal were determined in co-pyrolyzed SSL with willow (8:2, 6:2 w/w) at 500, 600, and 700 °C using two different carrier gases (N₂ or CO₂). The study investigated the relationship of metal content and bioavailability to toxicity of biochars towards bacteria (Vibrio fischeri), plants (Lepidium sativum), and arthropods (Folsomia candida). For the biochar produced at a ratio of 6:4 (SSL:willow), the content of most metals significant decrease (P ≤ 0.05) from 5.9% to 28.9%. Co-pyrolysis of SSL with willow decreased water extractable metal concentrations (Ba, Cd, Cu, Fe, Mn, Ni, and Zn) from 8.0% to 100%. The CO₂ resulted from 6 to 200 % increase (P ≤ 0.05) of metal content relative to the biochar pyrolyzed in N₂. An increase in pyrolysis temperature caused a higher concentration of the metals in the biochars. The available content of most metals decreased from 9 to 100 %. The adverse effect of these biochars on living organisms was reduced due to a stronger binding of the metals (especially Cu and Cd) with the biochar matrix. The negative impact of Cd, Cr, and Cu on living organisms was also confirmed by principal component analysis (PCA).

Reduction of polycyclic aromatic hydrocarbons (PAHs) emission from household coal combustion using ferroferric oxide as a coal burning additive

Household coal combustion is identified to be the second largest emission source of polycyclic aromatic hydrocarbons (PAHs) in China. In this study, ferroferric oxide (Fe₃O₄) was used as a coal burning additive to reduce PAHs emission from coal combustion in a household coal stove. The results showed that Fe₃O₄ participated in the coal combustion process. The addition of Fe₃O₄ reduced the release of PAHs during the coal combustion process, and could improve the residence capacity of ash residue to these PAHs. Toxic equivalent quantity (TEQ) of PAHs in flue gas from combustion of coal mixed with Fe₃O₄ was less than that from the raw coal combustion. For a typical combustion temperature of 850 °C, the TEQ of PAHs for the mixture of coal and 2.0 wt% Fe₃O₄ decreased 21.98% compared to that for the raw coal. The abundant active surface oxygen species originated from the phase transformation of iron oxides probably accelerated the cracking of PAHs, and hence led to the reduction of PAH emissions and their TEQ. The study could help to develop new technology for reduction of PAHs emission from household coal combustion.

Carbon dioxide as a carrier gas and mixed feedstock pyrolysis decreased toxicity of sewage sludge biochar

The common use of sewage sludge (SSL)-derived biochar can be limited due to contaminants present in SSL, which may affect SSL-derived biochar toxicity. We propose the reduction of SSL-derived biochar toxicity by it co-pyrolysis with biomass and in CO₂ atmosphere. Ecotoxicity of biochars produced at 500, 600, and 700 °C from SSL and SSL with the addition of willow (at a ratio of SSL:willow - 8:2 and 6:4, w/w) in an atmosphere of N₂ or CO₂ were investigated. The toxicity of aqueous extracts derived from the biochars (Lepidium sativum - Elongation test, Vibrio fischeri - Microtox) or solid-phase toxicity (Lepidium sativum - Phytotoxkit F, Folsomia candida - Collembolan test) was also studied. SSL-derived biochar produced at N₂ atmosphere usually was toxic for all tested organisms. Co-pyrolysis of mixed feedstock reduced the toxicity of the produced biochar. In the case of biochars produced from SSL and willow under N₂ atmosphere decrease in inhibition of F. candida reproduction (from 27 to 58%) or its stimulation (from 7 to 30%) in comparison to SSL alone derived biochar, was observed. Co-pyrolysis of SSL with willow significantly reduced the toxicity of extracts the SSL-derived biochar towards L. sativum. The aqueous extracts obtained from the biochars produced at temperatures of 500 and 600 °C with willow addition were also less toxic to V. fischeri than the biochars produced from SSL alone. The change of carrier gas from N₂ to CO₂, regardless of the feedstock used, in most cases reduced toxicity or positively affected the test organisms. This was probably caused by changes in the physicochemical properties and content of contaminants in the biochars produced in an atmosphere of CO₂, compared to N₂. An exception was root growth inhibition in the solid phase tests where no significant differences were found between biochars produced in N₂ and CO₂.

Effect of sulfamethazine on surface characteristics of biochar colloids and its implications for transport in porous media

Antibiotics are contaminants of emerging concern due to their potential effect on antibiotic resistance and human health. Antibiotics tend to sorb strongly to organic materials, and biochar, a high efficient agent for adsorbing and immobilizing pollutants, can thus be used for remediation of antibiotic-contaminated soil and water. The effect of ionizable antibiotics on surface characteristics and transport of biochar colloids (BC) in the environment is poorly studied. Column experiments of BC were conducted in 1 mM NaCl solution under three pH (5, 7, and 10) conditions in the presence of sulfamethazine (SMT). Additionally, the adsorption of SMT by BC and the zeta potential of BC were also studied. The experimental results showed that SMT sorption to BC was enhanced at pH 5 and 7, but reduced at pH 10. SMT sorption reduced the surface charge of BC at pH 5 and 7 due to charge shielding, but increased surface charge at pH 10 due to adsorption of the negatively charged SMT species. The mobility of BC was inhibited by SMT under acidic or neutral conditions, while enhanced by SMT under alkaline conditions, which can be well explained by the change of electrostatic repulsion between BC and sand grains. These findings imply that pH conditions played a crucial role in deciding whether the transport of BC would be promoted by SMT or not. Biochar for antibiotics remediation will be more effective under acidic and neutral soil conditions, and the mobility of BC will be less than in alkaline soils.

Sorption of ionic and neutral species of pharmaceuticals to loessial soil amended with biochars

To clarify the impact of biochar amendment on soil sorption for coexisting pharmaceuticals, wheat straw-derived biochars pyrolyzed at 300 and 700 °C (labeled as WS300 and WS700, respectively) were prepared. Batch experiments on ketoprofen (KTP), atenolol (ATL) and carbamazepine (CBZ) sorption to biochars, loessial soil and biochar-amended soils were conducted. The results indicated that sorption affinity of different species of pharmaceuticals to WS300 and WS700 was in the order of cationic ATL > neutral CBZ > anionic KTP. Cationic ATL had the highest sorption to biochars due to electrostatic attraction. Coexisting ATL, CBZ and KTP competed for the shared adsorption sites on carbonized phase of biochars, and π-π interactions were proposed to be the main sorption mechanism. Sorption coefficients (K_d) and nonlinearity of ATL, CBZ and KTP to soil increased when biochar was added (5% by weight), especially for WS700 with higher specific surface area. K_d values of the three pharmaceuticals to WS700-amended soil in either single solute or bisolute system were one to two orders of magnitude higher than those to soil, indicating the promoting role of WS700 in sorption of coexisting pharmaceuticals in soil. The study demonstrated the enhanced and competitive sorption of ionic and neutral species of pharmaceuticals to soil amended with biochars, which is helpful in designing biochar as effective sorbents for immobilization of pharmaceuticals in soil remediation.

Enhanced phenanthrene removal in aqueous solution using modified biochar supported nano zero-valent iron

The present work investigated the removal behaviour of phenanthrene (PHE) by nano zero-valent iron immobilized on alkali modified biochar (nZVI/MB). Batch studies showed that nZVI/MB enhanced PHE removal by 4.9 times that of the nZVI and 1.2 times that of modified biochar (MB) alone, due to the greater surface area and the inhibited aggregation of nZVI on the surface of MB. Transmission electron microscopy images revealed that the spherical nZVI particulates with an average diameter of 32 nm uniformly dispersed on the surface of MB. The PHE removal fitted well with the pseudo-second-order model (R²>0.98) was an endothermic and spontaneous process. The forces of π-π interaction, hydrophobic interaction and reduction of supported nZVI were contributed to PHE removal process. In addition, the PHE degradation products in solution were determined by gas chromatograph-mass spectrometer after reaction with nZVI/MB.

Carbon dioxide as a carrier gas and biomass addition decrease the total and bioavailable polycyclic aromatic hydrocarbons in biochar produced from sewage sludge

Organic-solvent extractable (C_tot) and freely dissolved (C_free) polycyclic aromatic hydrocarbons (PAHs) (US EPA 16 PAHs) were determined in biochars produced from the mixture of sewage sludge and sewage sludge and willow (8:2 or 6:4, w/w). The pyrolysis was carried out at 500, 600, and 700 °C using two different carrier gases (N₂ or CO₂). Addition of willow and the change of carrier gas from N₂ to CO₂ reduced C_tot PAHs (from 7.0 to 52%) and C_free PAHs (15-29%) content. Co-application of willow and SSL and the use of CO₂ as a carrier gas also beneficially affected the PAHs profile. The biochars produced with willow addition and/or in a CO₂ atmosphere were characterized by a lower (from 9.0 to 62.8%) percentage of 3-6-ring PAHs (C_tot) than the biochars derived from sewage sludge alone in N₂ atmosphere. The contribution of individual C_free PAHs did not differ significantly between biochars. The presence of willow during pyrolysis influenced the direction of the changes in the C_tot PAH content depending on the pyrolysis temperature. For SSL alone, regardless of the carrier gas used, the content of C_tot PAHs was observed to decrease with increasing temperature, whereas in the presence of willow temperature did not affect significantly (P ≥ 0.05) the C_tot PAHs content. The change of carrier gas from N₂ to CO₂ increased the affinity of the biochars to PAHs as confirmed by the distribution coefficients log K_TOC.

Polycyclic aromatic hydrocarbons (PAHs) formation during the fast pyrolysis of hazardous health-care waste

Health-care waste management is a challenge for the health sector. Currently, pyrolysis technologies are being used to treat medical waste that can convert it to a hydrocarbon fuel. In the present study, hazardous health-care waste was pyrolyzed using a continuous tubular fast pyrolysis reactor. Mass balance analysis and formation of the 16 polycyclic aromatic hydrocarbons (PAHs), characterized by USEPA as priority pollutants, and was studied during the pyrolysis process in a wide range of operation conditions, i.e., reaction temperature (300-700 °C), residence time (100-190 s) and waste particle size (1-3 cm). Response surface methodology (RSM) and central composite design (CCD) were applied to optimize the operating variables. Cracking and decomposition of feedstock occurred almost optimally in 700 °C resulting in the generation of 73.4% liquid and 24.1% char. The PAHs were characterized in significant concentrations in pyrolytic oil (121-29440 mg/lit) and char (223-1610 mg/kg) products. The formation of total USEPA listed PAH components varied by the operating ranges of temperature, residence time and waste size. In the pyrolytic oil phase, the formation of total PAHs was drastically increased by increasing the waste particle size. It is also found that increasing the temperature and having longer residence times have a high influence on the total 16 USEPA PAHs formation rate in the char phase. It is concluded that fast pyrolysis of hazardous health-care waste, as thermal treatment method, would influence the formation and destruction of PAHs and their fraction to a different extent depending on the role of operating variables.

Quantitative evaluation of relationships between adsorption and partition of atrazine in biochar-amended soils with biochar characteristics

Atrazine (ATZ) adsorption in two natural soils amended with biochars produced from different feedstocks at 300, 500, and 700 °C were investigated; further, the relationships between the surface and partition adsorption capacities of ATZ in biochar-amended soils with biochar characteristics were quantitatively evaluated. The results revealed that high aromaticity, hydrophobicity, and low polarity of biochar facilitated ATZ adsorption. The addition of selected biochars significantly increased the adsorption of ATZ on paddy soil (PS) and black soil (BS) by 5.2–7.5 times and 2.3–4.2 times, respectively. On the contrary, the degree of increase in surface adsorption was much higher than that in partition adsorption, mainly due to the role of the specific adsorption of ATZ on biochar. Meanwhile, the respective contributions of surface and partition adsorptions to the total ATZ adsorption on biochar-amended soil changed with different addition amounts of biochar. The multiple nonlinear regression analysis demonstrated the linear dependence of H/C ratio, (O + N)/C ratio, and specific surface area (SSA) of biochar on the surface adsorption capacity of biochar-amended PS and BS, as well as the linear dependence of organic carbon and ash contents on the partition adsorption capacity of biochar-amended PS and the linear dependence of the H/C ratio and SSA on the partition adsorption capacity of biochar-amended BS. In biochar-amended soil systems, interactions between biochar and soil could affect ATZ adsorption, and organic matter in biochar might compensate for the role of soil organic matter in the competition for adsorption sites with a decrease in the biochar pyrolysis temperature.

Adsorption of atrazine (ATZ) in two natural soils amended with different biochars was investigated, and the relationships of adsorption capacity of biochar-amended soils with biochar characteristics were also quantitatively evaluated.

Influence of aromatic structure and substitution of carboxyl groups of aromatic acids on their sorption to biochars

In order to clarify the influence of aromatic structure and COOH substitution of aromatic acids on their sorption to biochars, benzoic acid (BA), phthalic acid (PA), hemimellitic acid (HA), 2-biphenylcarboxylic acid (2-BA), 1-naphthoic acid (1-NA) and naphthalene were selected as model sorbates. Batch experiments on sorption of them to wheat straw-derived biochars at 300 °C (WS300) and 700 °C (WS700) were conducted. Results showed that WS700 with higher specific surface area and pore volume had faster and higher sorption of aromatic acids than WS300. Sorption affinity of aromatic acids decreased with increasing number of aromatic rings (BA > 1-NA > 2-BA), and was weakened by COOH substitution (BA > PA > HA). This was likely due to the π-electron delocalization into additional ring, reduced contact area of nonplanar aromatic structure on biochar surfaces, size exclusion of larger molecules in smaller pores of biochars and decreased hydrophobicity of aromatic acids by COOH substitution that abated the sorption. Dissociation of COOH substitution of aromatic acids also weakened their sorption to biochars due to the lower hydrophobicity of anionic species, and electrostatic repulsion between anionic species and negatively charged surface of biochars.

Phosphorus speciation in sewage sludge and the sludge-derived biochar by a combination of experimental methods and theoretical simulation

Sewage sludge is an inevitable byproduct from municipal wastewater treatment processes and conversion of sewage sludge into high value-added biochar is an effective strategy for resource utilization of sewage sludge. The characterization on P speciation is important to control the practical applications and environmental behavior of the sewage sludge and its derived biochar. The mobility and bioavailability of P is closely related to its speciation, but knowledge gap in P speciation is still existed which needs to be narrowed by a systematic study including existing experimental methods and techniques as well as theoretical prediction. To achieve a comprehensive understanding of P speciation, this study conducted a series of research combining conventional fractionation of P with consideration of major concomitant elements (Al, Ca, Fe), advanced analytical techniques (solution and solid-state ³¹P nuclear magnetic resonance (NMR), X-ray diffraction (XRD)), and theoretical simulation with respect to solubility of major elements in different acid-base extractants. Results showed that Ca and Fe were dominantly extracted by HCl whereas P and Al were both NaOH- and HCl-soluble. Inorganic orthophosphates were detected as predominant molecular configurations of P from solution ³¹P NMR spectra, while the existence of calcium and aluminum orthophosphates was revealed by solid-state ³¹P NMR. Moreover, the poor-crystalline AlPO₄ mineral was further evidenced by XRD patterns of the sewage sludge and biochar. Finally, a theoretical simulation of P-containing minerals was performed on the basis of results above, which suggested the existence of variscite/berlinite and amorphous Ca₃(PO₄)₂ in the sludge and biochar. This study does not only explore the P speciation in the sewage sludge and its derived biochar, but also provides a methodology for further research on P speciation. Through the intensive study on the environmental behavior of P, this work might further contribute to the fundamental knowledge basis for the recycle of P during integrate waste management.

Magnetite/Lanthanum hydroxide for phosphate sequestration and recovery from lake and the attenuation effects of sediment particles

An effective approach for eutrophication control and phosphate recovery remains a longstanding challenge. Herein, we present a new technique for phosphate sequestration in lake and phosphate recovery using novel magnetically recoverable magnetite/lanthanum hydroxide [M-La(OH)₃] hybrids that can be prepared using a simple one-pot synthesis method. Batch studies show that M-La(OH)₃ exhibits a strong sorption towards phosphate with sorption capacities of up to 52.7 mg-P/g at pH 7.0 in water. A simple model indicates that the efficiency of M-La(OH)₃ for phosphate sequestration in lake is significantly attenuated by 34-45% compared to that in water, due to interference from sediment particles. However, our results demonstrate that sediments suspensions mixed with a M-La(OH)₃ content of 1-3% exhibit a capability of up to 1.2 mg-P/g for sequestering external phosphate compared with that of 0.2 mg-P/g for pristine sediment at pH 7.3. M-La(OH)₃-mixed sediment suspensions appear to effectively sequester phosphate over an environmentally relevant pH range from 4 to 8.5. Phosphorus (P) fractionation experiments indicate that the enhanced phosphate sorption by M-La(OH)₃-mixed sediment suspensions is mainly due to the increased fractions of NaOH-P and inorganic P. This work indicates that the M-La(OH)₃ has the potential for phosphate sequestration and recovery from lake.