Phosphate Removal Research Articles

Parthenium hysterophorus-derived iron-coated biochar: a sustainable solution for nitrate and phosphate removal from water

Parthenium hysterophorus-derived iron-coated biochar: a sustainable solution for nitrate and phosphate removal from water

Nutrients removal in overloaded WWTP by intermittently aerated IFAS: Effects of biofilm carrier and intermittent aeration cycle

Updating of the current Urban Waste Water Treatment Directive (91/271/EEC) will demand stricter regulations for nutrients removal. In this frame, wastewater treatment plants (WWTPs) of small-to-medium potential will face new challenges for achieving process intensification. Integrating intermittent aeration (IA) and integrated fixed-film activated sludge (IFAS) technologies could be a promising solution to meet such requirements. This study analyzed how IA cycles affected nutrients removal in IFAS reactors with different biofilm carriers (e.g., plastic and sponge media). The plants responses to different carbon/nitrogen/phosphorous (C/N/P) ratios were evaluated while operating under low sludge retention time (SRT) to simulate overloaded conditions.A short IA cycle (1 h) with an aeration/not aeration ratio of 2:1 enabled high organic carbon and nitrification performances when operating at high C/N/P (11.8/1/1), whereas low denitrification and phosphorous removal yields were obtained because of the short not-aerated phase. Decreasing C/N ratio (8.8/1/1) without changing the IA cycle resulted in nitrification worsening because of the reduced metabolic kinetics of biofilm. Under such load conditions, a higher IA cycle (2 h) was necessary to improve process performance. A longer not-aerated phase was also positive for denitrification and phosphorous removal because of the establishment of anoxic and anaerobic environments within the bulk and inner biofilm layers. Besides, results suggested that sponge carriers offered advantages over plastic ones, enabling a higher biofilm retention capacity, better nutrient removal, as well as robustness and resilience to operating condition changes. This would result in simpler management systems for implementing the IA process, thus reducing process complexity and costs.

Preparation of a novel LC@MWCNTs membrane and its application for enhanced phosphate removal and fouling control

To control the eutrophication originating from phosphate discharge, a novel adsorptive membrane was prepared by vacuum filtrating lanthanum carbonate modified multi-walled carbon nanotubes (LC@MWCNTs) on the UF membrane. The LC@MWCNTs were firstly made using an in-situ method by adding MWCNTs to LaCl3·7H2O solution and forming lanthanum carbonate under alkaline conditions. The adsorption experiments exhibited that the maximum adsorption capacity of LC@MWCNTs was 77.58 mg P/g at pH 5. And the phosphate adsorption by LC@MWCNTs was not predominantly reliant on electrostatic interaction, but rather achieved through chemical interactions. Then, the prepared LC@MWCNTs membrane was systematically evaluated for its phosphate removal efficiency and anti-fouling performance during filtration. With the initial phosphate concentration of 1 mg P/L and membrane flux of 378 L·m−2 h−1, the phosphate removal by LC@MWCNTs membrane approached almost 100 %. Moreover, the LC@MWCNTs membrane exhibited higher permeability (281.6 L·m−2h−1bar−1) and effectiveness for humic acid (HA) removal (75 %), and LC@MWCNTs membrane mitigated the fouling caused by HA. XPS, FTIR and XRD elucidated that phosphate removal by LC@MWCNTs membrane primarily through the formation of La-O-P inner-sphere complexes via ligand exchange, resulting in the formation of adsorption product LaPO4·0.5H2O. Under strong alkaline conditions, the LC@MWCNTs membrane rapidly restored its phosphate removal performance (30 min) with no significant detachment of the LC@MWCNTs layer, indicating its good recovery and reusability performance. Additionally, the LC@MWCNTs membrane could continuously remove phosphate from actual water, confirming its potential for future practical applications.

Sulfadiazine degradation by hydroxyl radical and direct electron transfer pathways in the self-prepared boron doped diamond electrochemical process

Sulfonamide antibiotics are frequently detected in livestock wastewater, seriously harming the ecological environment and human health. Boron-doped diamond (BDD) electrochemical process has prominent potential in degrading organic pollutants from special industrial wastewater. In this work, the degradation efficiency and mechanism for sulfadiazine (SDZ) with the prepared BDD electrode were investigated. Scanning electron microscopy (SEM) and Raman spectroscopy revealed a 2 μm thick, compact, and crack-free BDD film on silicon. The BDD's oxygen evolution potential was 1.47 V. About 93.3 % of SDZ in the synthetic wastewater was removed under the conditions of a current density of 40 mA/cm2, electrode spacing of 20 mm, electrolyte concentration of 40 mM, and an initial pH of 8. Hydroxyl radical and direct electron transfer (DET) mainly contributed to SDZ degradation based on specific quencher tests and electrochemical analysis. The possible transformation pathways of SDZ were proposed according to the detected oxidation products and DFT calculation, mainly including amino hydroxylation, sulfur dioxide extrusion, and pyrimidine heterocyclic ring opening. Furthermore, the toxicity of intermediates products markedly weakened compared to that of SDZ. The presence of ion chloride could slightly improve the removal of SDZ, while bicarbonate and phosphate inhibited the SDZ degradation. In addition, the efficient removal of chemical oxygen demand and SDZ in the effluent of aerobic biological treatment effluent of actual livestock wastewater was confirmed. To sum up, BDD electrochemical oxidation is a viable approach for the advanced treatment of livestock wastewater.

Fe(III)-modified bamboo biochar for the removal of phosphate from synthetic and field stormwater runoff

Fe(III)-modified bamboo biochar for the removal of phosphate from synthetic and field stormwater runoff

Enhancing immobilized Chlorella vulgaris growth with novel buoyant barium alginate bubble beads

Microalgae immobilization in alginate beads shows promise for biomass production and water pollution control. However, carrier instability and mass transfer limitations are challenges. This study introduces buoyant barium alginate bubble beads (BABB), which offer exceptional stability and enhance Chlorella vulgaris growth. In just 12 days, compared to traditional calcium alginate beads, BABB achieved a 20 % biomass increase while minimizing cell leakage and simplifying harvesting. BABB optimization involved co-immobilization with BG-11 medium, enrichment of CO2 in internal bubbles, and the integration of Fe nanoparticles (FeNPs). In the open raceway pond reactor, these optimizations resulted in a 39 % increase in biomass over 7 days compared to the unoptimized setup in closed flasks. Furthermore, enhancements in pigment and organic matter production were observed, along with improved removal of ammonia nitrogen and phosphate. These results highlight the overall advantages of BABB for microalgae immobilization, offering a scientific foundation for their effective utilization.

Efficient removal of phosphate and fluoride from phosphogypsum leachate by lanthanum-modified zeolite: Synchronous adsorption behavior and mechanism

Phosphogypsum is a common large-tonnage by–product in phosphorous chemicals industry, its stacking not only causes severe environmental problems, but also leads to a serious waste of phosphate and fluoride resources. The objective of this study was to tackle the recycling treatment of phosphogypsum leachate by using a highly efficient adsorbent lanthanum hydroxide-modified zeolite (LMZ). The adsorption behaviors of phosphate and fluoride by LMZ in the coexisting system under static and dynamic conditions were studied. And further, the competitive adsorption mechanism involved was analyzed. The results showed that LMZ possessed excellent adsorption performance toward both phosphate and fluoride in the single system, but the fluoride adsorption capacity decreased by 57.9 % in the coexisting system, with no change in phosphate adsorption. In the competitive adsorption process, ligand exchange interaction on La active sites contributed most to phosphate adsorption, while fluoride could be adsorbed onto LMZ via electrostatic attraction, surface precipitation with Al sites, and hydrogen bonds with hydroxyl groups in La−OH and P−OH. In actual phosphogypsum leachate, the removal of phosphate had priority over the removal of fluorine. Under continuous adsorption condition, the concentration of phosphorus and fluoride could be decreased to below 0.5 and 1.0 mg/L, respectively, meeting the safe concentration in drinking water. This study promotes the application of La–based adsorbents in the treatment of phosphogypsum leachate, and provides a green and sustainable strategy toward practical phosphorus and fluorine recovery.

Effective adsorption of phosphate using a Mg–Al–La composite from synthetic/real wastewater: adsorptive behaviour, column tests and economic evaluation

ABSTRACT The present study utilised an adsorbent that integrates Mg with Al and La (i.e. MAL composite) to remove low-concentration phosphate from wastewater. The adsorption properties of MAL were identified through batch experiments of phosphate removal, in which the impacts of influencing factors such as initial pH and reaction time on the phosphate adsorption by MAL adsorbent were explored. Besides, the thermodynamics and kinetics were also investigated, where the phosphate adsorption follows the pseudo-second-order kinetics, indicating that chemisorption and internal diffusion control dominate the phosphate removal. Dynamic phosphate removal by MAL adsorbent was investigated using a fixed-bed column at different adsorbent particle sizes, flow rates and temperatures, in which the breakthrough curves were simulated. The phosphate removal by MAL adsorbent was examined at practical wastewater treatment, which achieves high efficiency and thus provides a preliminary basis for the commercial use of the adsorbent. Apart from this, the techno-economic analysis of phosphate adsorption was also conducted.

Isotherm, Kinetics, and Adsorption Mechanism Studies of Coal Gasification Coarse Slag as Highly Efficient Phosphate Adsorbents

This study investigates the efficacy of a novel low-cost phosphate adsorbent, denoted as SH-CGCS, derived from coal gasification coarse slag (CGCS) via an alkali activation method. SH-CGCS is a mesoporous material with a specific surface area (64 m2/g) approximately six times larger than CGCS (11 m2/g), which enhances its adsorption capacity compared with CGCS. Furthermore, SH-CGCS achieves a phosphate adsorption capacity of 38.5 mg/g in strongly acidic water (pH 3) and demonstrates robust acid resistance, which makes it particularly effective for phosphate removal from acidic wastewater. Results from coexisting anion experiments affirm the good adsorption selectivity of SH-CGCS for phosphate. Moreover, SH-CGCS exhibits proficiency in treating water containing low phosphate concentrations under flowing conditions. The maximum phosphate adsorption capacity of SH-CGCS calculated using the Langmuir model is 23.92 mg/g, surpassing that of other reported adsorbents. Importantly, saturated SH-CGCS can be regenerated and reused, which contributes to its practical applicability. The adsorption mechanisms of SH-CGCS for phosphate involve ligand exchange, inner-sphere complexation, surface precipitation, and electrostatic adsorption. Thus, this study not only enhances the overall utility of CGCS but also presents a simple and efficient method for removing phosphate. Our findings indicate that SH-CGCS holds considerable potential as a phosphate adsorbent, offering a promising solution for wastewater treatment.

Simultaneous removal of ammonium, phosphate, and phenol via self-assembled biochar composites CBCZrOFe3O4 and its utilization as soil acidity amelioration

ABSTRACT High concentrations of ammonium, phosphate, and phenol are recognized as water pollutants that contribute to the degradation of soil acidity. In contrast, small quantities of these nutrients are essential for soil nutrient cycling and plant growth. Here, we reported composite materials comprising biochar, chitosan, ZrO, and Fe3O4, which were employed to mitigate ammonium, phosphate, and phenol contamination in water and to lessen soil acidity. Batch adsorption experiments were conducted to assess the efficacy of the adsorbents. Initially, comparative studies on the simultaneous removal of NH4, PO4, and phenol using CB (biochar), CBC (biochar + chitosan), CBCZrO (biochar + chitosan + ZrO), and CBCZrOFe3O4 (biochar + chitosan + ZrO + Fe3O4) were conducted. The results discovered that CBCZrOFe3O4 exhibited the highest removal percentage among the adsorbents (P < 0.05). Adsorption data for CBCZrOFe3O4 were well fitted to the second-order kinetic and Freundlich isotherm models, with maximum adsorption capacities of 112.65 mg/g for NH4, 94.68 mg/g for PO4 and 112.63 mg/g for phenol. Subsequently, the effect of CBCZrOFe3O4-loaded NH4, PO4, and phenol (CBCZrOFe3O4-APP) on soil acidity was studied over a 60-day incubation period. The findings showed no significant changes (P < 0.05) in soil exchangeable acidity, H+, Mg, K, and Na. However, there was a substantial increase in the soil pH, EC, available P, CEC, N-NH4, and N-NO3. A significant reduction was also observed in the available soil exchangeable Al and Fe (P < 0.05). This technique demonstrated multi-functionality in remediating water pollutants and enhancing soil acidity.

Investigation of Phosphate Removal from Aqueous Solutions Using Zinc Extraction Waste

It is important for waste management to economically evaluate the solid leach residues released in zinc production facilities and classified as hazardous waste due to the metals they contain, without harming the environment and human health. Although the disposal of these residues often requires special technologies, hazardous wastes are left to the environment or landfills due to the expense of these technologies and the inadequacy of legal sanctions in some cases. For this reason, it is important from an economic and environmental perspective to evaluate these residues and bring them into the industry. In this study, lead cake formed during zinc extraction production, brought from Kayseri Çinkur enterprises, was used. Since this waste contains high amounts of lead as well as zinc and iron, the conditions for removing phosphate from aqueous solutions were investigated. Phosphate removal adsorption isotherms were obtained using the obtained batch test results. Additionally, some thermodynamic quantities regarding phosphate removal were calculated. As a result of the experiment, it was determined that the P removal efficiency from aqueous solutions significantly depends on the solution pH and the dose of waste lead cake. It was also determined that phosphate removal from aqueous solutions obeyed the Langmuir and Freundlich isotherm. Additionally, it was observed that phosphate adsorption equilibrium was established after a period of 120 min. By mixing 100 mg/L phosphate solution with pH 7.69 with 20 g/L lead cake without any addition and contacting for 120 minutes, approximately 74% of the phosphate can be effectively removed by adsorption.

Lanthanum and cerium functionalised forestry waste biochar for phosphate removal: Mechanisms and real-world applications

Phosphorus as a diminishing finite resource, yet is an essential element for the growth of biota. However, elevated concentrations in water can imbalance ecosystems and cause eutrophication. To address both problems, two highly efficient biochars, namely La-OB and CeLa-OB were synthesised by lanthanum and cerium doping. The performance of La-OB and CeLa-OB were evaluated in both batch and dynamic regimes with synthetic phosphate (PO43--P) solutions and eutrophic lake water. PO43--P adsorption mechanisms were investigated in terms of pH, kinetics, isotherms, activation energy, thermodynamics and using in-depth characterisation (XPS, FTIR, XRD, BET, pHpzc and SEM-EDX). The feasibility of using such biochar in ‘real life’ situations was studied with column filtration of lake water with low and high PO43--P concentrations. Reusability/desorption and toxicity in the water environment was also considered. The mechanistic study showed that both biochars predominantly had inner-sphere complexes with La and Ce ligands (as a monolayer), while outer-sphere complexation was less common. The exothermic adsorption process followed the Elovich kinetic and Langmuir isotherm models, with a maximum adsorption capacity of 112 mg/g for La-OB and 40 mg/g for CeLa-OB. In column filtration trials the adsorption capacity reached 78 mg/g, while low metal leaching (0.08 mg/L) and low toxicity to Lepidium sativum germination were detected. The results indicated that these biochars, especially La-OB, could be used in circular economy-based water treatment.

Chlorella vulgaris-mediated bioremediation of food and beverage wastewater from industries in Mexico: Results and perspectives towards sustainability and circular economy

The food and beverage industries in Mexico generate substantial effluents, including nejayote, cheese-whey, and tequila vinasses, which pose significant environmental challenges due to their extreme physicochemical characteristics and excessive organic load. This study aimed to assess the potential of Chlorella vulgaris in bioremediating these complex wastewaters while also producing added-value compounds. A UV mutagenesis treatment (40 min) enhanced C. vulgaris adaptability to grow in the effluent conditions. Robust growth was observed in all three effluents, with nejayote identified as the optimal medium. Physicochemical measurements conducted pre- and post-cultivation revealed notable reductions of pollutants in nejayote, including complete removal of nitrogen and phosphates, and an 85 % reduction in COD. Tequila vinasses exhibited promise with a 66 % reduction in nitrogen and a 70 % reduction in COD, while cheese-whey showed a 17 % reduction in phosphates. Regarding valuable compounds, nejayote yielded the highest pigment (1.62 mg·g−1) and phenolic compound (3.67 mg·g−1) content, while tequila vinasses had the highest protein content (16.83 %). The main highlight of this study is that C. vulgaris successfully grew in 100 % of the three effluents (without additional water or nutrients), demonstrating its potential for sustainable bioremediation and added-value compound production. When grown in 100 % of the effluents, they become a sustainable option since they don't require an input of fresh water and therefore do not contribute to water scarcity. These findings offer a practical solution for addressing environmental challenges in the food and beverage industries within a circular economy framework.

Enhanced phosphate removal and antibacterial action using hierarchically structured La MOF-20%-C adsorbents and filter membranes

To enhance the phosphate removal performance, a porous material (La MOF-20 %-C) was prepared by selectively removing the thermally unstable NH2-BDC ligand from a lanthanum dual organic ligand MOF through pyrolysis. This innovative approach equips La-MOF-20 %-C with dual functionalities: high phosphate adsorption capacity and robust antibacterial effects. The adsorbent showcased a remarkable phosphate adsorption capacity of 97.24 mg P/g and reached equilibrium within 90 min. The material exhibits good anti-interference capability, and the presence of multiple coexisting ions does not affect its adsorption performance. Additionally, it can be used over a wide pH range (3.0–8.0) and has good reusability. Mechanistic studies indicated that electrostatic attraction and ligand exchange were the primary mechanisms for phosphate adsorption. Moreover, La MOF-20 %-C effectively inhibited the metabolic activities of Escherichia coli and Staphylococcus aureus through phosphorus starvation and electrostatic attraction, demonstrating significant antibacterial properties. Importantly, the fabrication of this material into a filter membrane enabled the successful treatment of 16.8 L of actual wastewater, achieving an overall phosphate removal rate of over 85 %, and effectively removing total bacteria. These findings highlight La MOF-20 %-C as a highly promising material with dual functionality for phosphate removal and bacterial inhibition.

Adsorptive removal of phosphate from aqueous solutions using FeCl3‐immobilized melamine‐formaldehyde‐urea resin

AbstractThe surplus phosphorus in aquatic environments trigger eutrophication, an irreversible pollution stage marked by the rapid growth of algae and water plants, a decline in dissolved oxygen levels, and the emergence of dead zones. To address this critical issue, this study focuses on the removal of phosphorus in form of phosphate from aqueous solutions. The research involves the synthesis and characterization of FeCl3‐immobilized melamine‐formaldehyde‐urea resin, an innovative adsorbent, its characterization through Fourier transform infrared spectroscopy, and the evaluation of its adsorption capacity based on Langmuir and Freundlich equilibrium models. The experimental adsorption data fits well with pseudo‐second order kinetic model. Optimal adsorption parameters are carried with batch adsorption technique for 60 min using 0.5 g of adsorbent at pH = 2, achieving 15.55 mg g−1 adsorption capacity, and conducting experiments with tap‐water samples to replicate real‐world scenarios. The research findings have the potential to advance sustainable wastewater treatment technologies and contribute to the mitigation of nutrient pollution in aquatic ecosystems, addressing a pressing environmental concern.

Iron sulfide mineral/polylactic acid mixotrophic biofilter for simultaneous nitrate and phosphate removal

Heterotrophic denitrification based on polylactic acid (PLAHD) can remove nitrate effectively, but it is expensive and can't remove phosphate. Autotrophic denitrification based on iron sulfide (ISAD) can simultaneously remove nitrate and phosphate cost-effectively, but its nitrate rate is slow. So, iron sulfide mineral/polylactic acid mixotrophic biofilter (ISPLAB) was constructed to combine advantages of ISAD and PLAHD. ISPLAB achieved nitrogen and phosphorus removal rates of 98.04 % and 94.12 %, respectively, at a hydraulic retention time (HRT) of 24 h. The study also revealed that controlling molecular weight (Mw) of PLA improved the release of soluble organic matter; adding iron sulfide enhanced the hydrolysis of PLA and precipitated PO43− of Fe2+/Fe3+, thereby facilitated simultaneous nitrogen and phosphorus removal. Microbial community analysis resulted that denitrifying bacterias (Phaeodactylibacter and Methylotenera), sulfur-reducing bacterias (Hyphomicrobium), sulfur-oxidizing bacteria (Denitratisoma), iron-reducing bacteria (Romboutsia) and hydrolyzed bacterias (norank_f_norank_o_1–20 and norank_f_Caldilineaceae) coexisted in the ISPLAB system. Organics and iron sulfide drived the denitrification process in ISPLAB.

Mesopore-rich La-based metal organic framework derivatives for phosphorus removal from mariculture tailwater

Deep dephosphorization of mariculture tailwater, a typical high-salinity and weakly alkaline wastewater, is difficult but essential for meeting ever-stricter stringent emission standards. Herein, we developed an alkaline-conversion method to prepare lanthanum-based metal organic framework (La–MOF) derivatives for efficient phosphate removal from mariculture tailwater. During the templated alkaline-conversion process, the strong-alkaline regent gradually broke the coordination bonds of La–MOF while maintained its macrostructure, and the La nodes liberated from the framework were then crystallized into La(OH)3. The universality of this conversion method was verified on other La–MOF precursors with different benzoic multicarboxylate ligands. Importantly, numerous mesopores were formed in the derivative interior, increasing the number of exposed active La sites and accessible transfer channels. Therefore, the derivative exhibited superior phosphate-adsorption performance with a high adsorption capacity (Langmuir Q0: 155.7 mg P/g) and a rapid adsorption rate. The obtained La–MOF derivative with stable structure had broad neutral–alkaline pH range adaptability, which was demonstrated satisfactory dephosphorization selectivity and high cyclic performance under different seawater conditions (coexisting anions, cations, H3BO3 and natural organic matter). Finally, the obtained mesopore-rich La–MOF derivative exhibited an excellent deep dephosphorization capacity for actual mariculture tailwaters collected from seven mariculture ponds. The reactive phosphate level was quickly reduced to an ultra-low effluent concentration (<0.05 mg P/L), demonstrating the promising application potential of the La–MOF derivative.

Enhanced adsorption of phosphate by rice straw-based biochar prepared via metal impregnation and bio-template technology.

Phosphate removal from water through green, highly efficient technologies has received much attention. Biochar is an effective adsorbent for phosphate removal. However, adsorption capacity of phosphate on pristine rice straw-based biochar was not optimistic due to low anion exchange capacity. In this study, Fe-modified, Mg-modified and MgFe-modified rice straw-based biochar (Fe-BC, Mg-BC and MgFe-BC) were prepared by combining metal impregnation and biological template methods to improve the adsorption capacity of phosphate. The surface characteristics of biochar and the adsorption behavior of phosphate on biochar were investigated. The modified biochar had the specific surface area of 17.910-39.336 m2/g, and their surfaces were rich in a large number of functional groups and metal oxides. Phosphate release was observed on pristine rice straw-based biochar without metal impregnation. The maximum adsorption capacities of phosphate on MgFe-BC, Mg-BC and Fe-BC at 298K were 6.93, 5.75 and 0.23mg/g, respectively. Adsorption was a spontaneous endothermic process, while chemical adsorption dominated and electrostatic attraction and pores filling existed simultaneously. Based on the site energy distribution theory study, the standard deviation of MgFe-BC decreased from 6.96 to 4.64kJ/mol with temperature increasing, which proved that the higher the temperature would cause the lower heterogeneity. Moreover, the effects of pH, humic acid, co-existing ions and ionic strength on phosphate adsorption of MgFe-BC were also discussed. MgFe-BC with fine pores and efficient adsorption sites is an ideal adsorbent for phosphate removal from water.

Biodegradable chelator GLDA intercalated magnesium/aluminum layered double hydroxides for efficient phosphate capture and removal from wastewater

Phosphate removal and recovery from wastewater play a vital role in controlling water eutrophication and facilitating resource recycling. Adsorbents of layered double hydroxides (LDHs) exhibit promising potential in the removal of phosphate; however, the removal efficiency often suffers insufficient as easy aggregation and inevitable loss of LDHs. Herein, a novel N, N–bis (carboxymethyl)–L–glutamic acid intercalated magnesium–aluminum LDH (GLDA@MgAl–LDH) were successfully synthesized. Intercalating with GLDA spawned dual functionality, i.e., the layer spacing expansion elevated the loading of phosphate, while GLDA also acted as additional binding sites toward phosphate. A higher phosphate capture (＞90%) was obtained in pH 5.0–8.0. Phosphate uptake was predominantly observed within the first1h, reaching equilibrium in approximately 4 h. The maximum adsorption capacity of 44.17 mg g–1 was attained for GLDA@MgAl–LDH at pH 6.70, which are far higher than that of pristine MgAl–LDH. GLDA@MgAl–LDH also had the excellent stability and reusability in five adsorption/desorption experiments. The GLDA@MgAl–LDH demonstrated significant efficacy in treating actual phosphate-containing wastewater in the fixed–bed adsorption column. Spectroscopic analysis, in conjunction with density functional theory, elucidated that GLDA intercalation enhanced the adsorption efficiency of MgAl–LDH. The key mechanisms facilitating phosphate removal included electrostatic attraction, anion and ligand exchange, and surface complexation. The above results highlight that GLDA@MgAl–LDH could serve as a promising and environmentally friendly candidate for phosphate treatment from the real wastewater.

High-efficiency lanthanum-modified zeolite adsorbents for phosphorus control and algal suppression: Preparation, characterization and mechanistic insights

The use of lanthanum (La)-based materials for phosphate removal from water has received increasing attention. However, challenges remain to enhance phosphate (P) sorption capacities and remove P at low concentrations. In this study, lanthanum modified zeolite materials loaded with different lanthanum types were synthesized by hydrothermal method. Based upon preliminary screening of synthesized La-modified zeolite materials in terms of phosphate sorption capacity and La content, lanthanum chloride-modified zeolite (LZ) is chosen for further study. Specifically, for these materials, phosphate sorption kinetics and isotherm behavior, and solution matrix effects (solution pH, and ionic strength) are reported. The developed LZ has a high sorption capacity of 124.38 mg/g, which exceeds that of most La-based adsorbents currently available. P uptake by LZ was pH-dependent with the highest sorption capacities observed over a pH range of 3 ∼ 9. The presence of coexisting ions (Cl-, SO42-, HCO3–) does not significantly affect the adsorption capacity of LZ. In a real treated wastewater effluent with phosphate concentration of 1.92 mg/L and 0.155 mg/L, 0.1 g/L and 0.01 g/L of LZ efficiently reduced the phosphate concentration to below 0.01 mg P/L. Electrostatic attraction and inner-sphere complexation were identified as the sorption mechanisms of phosphate by LZ. The acute toxicity test confirms that the addition of LZ has no acute toxicity effect on aquatic organisms. However, LZ shows indirect and direct inhibitory effects on algae growth, which is beneficial for the control of eutrophic water. Moreover, the exhausted LZ can be easily regenerated with over 70 % adsorption capacity remained during five recycles. Overall, LZ shows great application potential, and this work provides new insights into the molecular-level mechanism of phosphate sequestration by LZ.