Phosphate Removal Research Articles

Removal of Phosphate from Water by Iron/Calcium Oxide-Modified Biochar: Removal Mechanisms and Adsorption Modeling

Phosphorus (P) pollution is a leading cause of water eutrophication, and metal-modified biochar is an effective adsorbent with the ability to alter the migration capacity of phosphorus. This study uses bamboo as the raw material to prepare metal-modified biochar (ZFCO-BC) loaded with Fe and Ca under N2 conditions at 900 °C, and investigates its adsorption characteristics for phosphate. Batch experimental results show the adsorption capacity of the ZFCO-BC gradually increases (from 4.0 to 69.1 mg/g) as the initial phosphate concentration increases (from 2 to 900 mg/L), mainly through multilayer adsorption. Additionally, as the pH increases from 1 to 7, the adsorption capacity of the ZFCO-BC climbs to reach its maximum value of 48.4 mg/g with an initial phosphate concentration of 150 mg/L. At this pH, phosphate primarily exists as H2PO4− and HPO42−, which both readily react with Fe3+ and Ca2+ in the biochar. Furthermore, the addition of CO32−, HCO3−, NO3−, SO42−, F−, and Cl− each affect the removal rate of phosphate by less than 10%, indicating the ZFCO-BC has a highly efficient and selective phosphate adsorption capacity. A multi-column adsorption experiment designed to achieve long-term and efficient phosphorus removal treated 275.5 pore volumes (PVs) of water over 366 h. The cyclic adsorption–desorption experiment results show that 0.5 M NaOH can effectively leach phosphate from the ZFCO-BC. Observations at the molecular level from P K-edge XANES spectra confirm the removal of low-concentration phosphate is primarily dominated by electrostatic attraction, while the main removal mechanism for high-concentration phosphate is chemical precipitation. This study demonstrates that ZFCO-BC has broad application prospects for phosphate removal from wastewater and as a potential slow-release fertilizer in agriculture.

Synthesis and Phosphate Removal of Ce/Mg-MOF-74

Synthesis and Phosphate Removal of Ce/Mg-MOF-74

Iron-loaded activated carbon cloth as CDI electrode material for selective recovery of phosphate.

This study investigated the efficacy of oxidised iron-loaded activated carbon cloth (Fe-ACC) for selective recovery of phosphorous. The capacitive deionisation (CDI) technology was employed, for rapid removal of phosphate, with the aim of reducing the reliance on high alkalinity environment for the regeneration of Fe-ACC electrode. Multiple experimental parameters, including applied potential, pH, and co-existing ions, were studied. Additionally, the CDI system was tested on a real water matrix (Lake Ormstrup, Denmark) to elucidate the electrodes' performance on selective recovery of phosphate. About 69 ± 10% of the adsorbed phosphate were released at pH 12 via pure chemical desorption, which was ~ 50% higher than that at pH 9. The CDI system successfully demonstrated the selective removal of phosphate from the lake water. It reduced the concentration of phosphate from 1.69 to 0.49mg/L with a 71% removal efficiency, while the removal percentages of other anions, namely chloride, sulphate, bromide, nitrite, nitrate, and fluoride, were 10%, 7%, 1%, 1.5%, 4%, and 7%, respectively.

Utilizing Waste Biomass from Agricultural and Forestry Sustainable Resources: Biomass Conversion to Functional Adsorbent Material for Efficient Removal of Total Phosphate in Practical Water.

The promotion of the utilization of waste agricultural and forestry resources (AFRs) as a means of combating environmental pollution represents an advanced and necessary development approach with the potential to achieve sustainable development. In this work, an advanced adsorbent with a functional Mg-Al bimetallic layer was prepared using waste sawdust biomass (WSD) as a raw material. The layer serves as the primary active component for adsorbing total phosphate from both simulated and real wastewater. The hierarchical structure of the Mg-Al bimetallic hydroxide-modified waste sawdust biomass (MA@WSD) has an abundance of nanosheets on its surface, providing ample binding sites and an enhanced specific surface area of 175.99 m2/g. Under the optimal conditions, the maximum removal efficiency toward phosphate can reach 99.99%. The adsorption of phosphate by MA@WSD follows the pseudo-second order kinetic (PSOK) model, indicating that chemisorption is the rate-determining step. Moreover, the thermodynamic data demonstrate the spontaneous nature of the adsorption process, indicating the favorable characteristics of the developed material. The adsorption mechanism can be summarized as the collaboration of physical adsorption, electrostatic interaction, and chemical adsorption. The results of the regeneration process indicate that MA@WSD exhibits a retention of 50.3% of its initial adsorption performance following the fifth testing cycle, thereby suggesting its potential for comparable reusability. The MA@WSD performs well in adsorbing total phosphate in real river water, and the removal efficiency of MA@WSD is evidently superior to commercial activated carbon, which is at least 70% higher than that of the commercial activated carbon. Besides, the 5-time average removal efficiency toward total phosphate by MA@WSD is 62.9%, evidently higher than the 29.1% of commercially available activated carbon, indicating its potential as an alternative for treating phosphorus-containing wastewater. The research provides theoretical support for harmless treatment, resource utilization, carbon sequestration, and emission reduction of waste biomass.

Selective and Efficient Phosphate Removal Using Ca–La Layered Double Hydroxide-Functionalized Sludge Biochar

Selective and Efficient Phosphate Removal Using Ca–La Layered Double Hydroxide-Functionalized Sludge Biochar

Removal of phosphate from wastewater using zirconium/iron embedded chitosan/alginate hydrogel beads: An experimental and computational perspective

Adsorptive removal of phosphate plays a crucial role in mitigating eutrophication. Herein, the Zr/Fe embedded chitosan/alginate hydrogel bead (Zr/Fe/CS/Alg) is reported as an effective phosphate adsorbent. This polymer nanocomposite is synthesized by the in-situ reduction of the metals on the polymer matrix. The synthesized adsorbent was characterized by the FTIR, SEM-EDX, TGA, BET, and XPS. The adsorbent showed a maximum phosphate adsorption capacity of 221.72 mg/g at pH 3. The experimental data fit well with the Freundlich isotherm and pseudo-second-order kinetics model, indicating a heterogeneous multilayer surface formation and a chemisorption-dominated adsorption process. Density Functional Theory (DFT) and Monte Carlo (MC) calculations revealed high negative adsorption energy due to the chemisorption of phosphate on the adsorbent. Hence, the major interactions such as electrostatic attraction, hydrogen bonding, and inner-sphere complexation of phosphate adsorption and Zr/Fe/CS/Alg hydrogel beads were investigated from the experimental and computational analysis. The negative values of thermodynamic parameters indicated a spontaneous, exothermic, and less random adsorption process. The synthesized adsorbent exhibited excellent selectivity toward phosphate and maintained 73 % efficiency after six adsorption/desorption cycles. The Zr/Fe/CS/Alg hydrogel beads reduced the phosphate concentration in real wastewater samples from 19.02 mg/L to 0.985 mg/L, suggesting that these nanocomposite hydrogel beads could be a promising adsorbent for real-world applications.

Copper-saturated chitosan beads (CuSCBs) for Enhanced phosphate removal

This study investigates the sequential use of non-cross-linked chitosan beads (CBs) for copper and phosphate adsorption, emphasizing copper site saturation and selective phosphate binding. Initially, CBs were loaded with copper until saturation was achieved, where all available sites were occupied by copper at an initial concentration of 100 mg/L. These copper-saturated chitosan beads (CuSCBs) were subsequently applied for phosphate adsorption, achieving a maximum adsorption capacity of 85.89 mg/g at pH 5. X-ray Photoelectron Spectroscopy (XPS) analysis revealed a shift in the Cu2O binding energy to lower values upon phosphate adsorption, indicating that phosphate ions interact primarily with the copper ions intercalated on the CBs rather than the chitosan matrix. Additionally, the nitrogen spectra showed no shift, confirming that the amine groups of chitosan do not participate in phosphate binding. The findings suggest a 1:1 interaction ratio between copper and phosphate ions, with each phosphate ion binding to one copper ion, creating a stable and selective adsorption site. The adsorption data fit the Langmuir isotherm and pseudo-second-order kinetic models, suggesting a homogeneous monolayer adsorption mechanism driven by chemisorption, where each copper site on the chitosan surface selectively binds one phosphate ion. Furthermore, the CuSCBs demonstrated minimal copper leaching and retained 90 % of their phosphate adsorption capacity over multiple adsorption–desorption cycles, highlighting their potential as effective and reusable adsorbents for water treatment applications targeting copper and phosphate removal.

Stable nutrient removal from wastewater with fluctuating seawater content ensured by an adaptable aerobic granular sludge microbiome

Seawater intrusion in coastal regions can alter the wastewater composition, threatening the microbial communities in wastewater treatment processes. An aerobic granular sludge (AGS) system was challenged by fluctuations in wastewater salinity levels promoted by seawater intrusion events for 286 days, divided into two stages. During stage I, the seawater content in wastewater increased stepwise, and over stage II the seawater content in wastewater oscillated throughout the day. Most of the time, the AGS effectively removed COD during the anaerobic phase, regardless of the wastewater salt content. Ammonium removal was slightly unstable (ca. 75 ± 19 %) during stage I, with nitrite release in the effluent. Over stage II, the ammonium content in the wastewater was fully removed. The nitrite content in the effluent decreased, and nitrate became the main nitrogen form released. Phosphate removal was quite unstable at the beginning, improving over time with complete removal achieved during stage II (ca. 98.4 ± 1.1 %). Taxa involved in nitrogen and phosphorous removal were identified in the AGS microbiome at both stages but with superior abundance in the latter stage. A diverse core microbiome, mainly composed of extracellular polymeric substances-producing bacteria (Thauera, Flavobacterium, Paracoccus) and denitrifying bacteria (Thiotrix, Azoarcus, Aequorivita) was identified in stage II. The AGS system efficiently managed daily oscillating seawater levels in wastewater, corroborated by the effective removal performance that seemed to be sustained by an adaptable AGS microbiome.

Capacitive deionization exploiting La-based LDH composite electrode toward energy efficient and selective removal of phosphate

Capacitive deionization (CDI) is a promising technology for removing phosphate from wastewater. Its practical implementation is however hindered by the constraints on the electrode materials. To boost the adsorption capacity, phosphate selectivity, and cost-effectiveness of the electrode, this study proposed a composite electrode blending Lanthanum-based layered double hydroxide (CaLa LDH) and activated carbon (AC). It capitalizes on the synergistic effects of electric double layer capacitance (EDLC) of AC and the diffusion-controlled charge storage (pseudocapacitive behavior) of CaLa LDH. By optimizing the mass ratios of the constituents and the electrode material loading capacities, the composite electrode AC/Ca-La LDH-5020 was developed, which contains 20 mg of 50 wt% CaLa LDH. This composition achieved a remarkable phosphate adsorption capacity of 34.8 mg P /g and a low energy consumption of 0.0051 kWh/g P in constant voltage (CV) mode. It represented a 241 % increase in adsorption capacity (mg P/g) and 71 % decrease in specific energy consumption (kWh/g P) compared to the electrode made solely of AC. Particularly the moderate inclusion of Lanthanum contributes to its cost-effectiveness. Moreover, further studies extensively examined the impacts of electrical driving force, including applied voltage in constant current (CC) mode and applied current in constant voltage (CV) mode, on the phosphate removal efficiency. The composite electrode remained stable performance with the presence of the high content of coexisting anions (e.g.，Cl−，SO42−, HCO3−, NO3−), obtaining high selectivity coefficient of phosphate over other anions. This study highlighted the practical potential of AC/Ca-La LDH composite electrode for advancing CDI technology for phosphate removal in an efficient, energy-saving and cost-effective manner.

Stormwater treatment in constrained urban spaces through a hybrid Sequential Sedimentation Biofiltration System

Urban areas face increasing pressures on water resources, necessitating innovative approaches to climate adaptation and water quality management. Nature-based Solutions (NbS) offer a sustainable pathway, yet their integration with existing infrastructure in urban settings remains occasional. This study presents a novel hybrid system—Sequential Sedimentation Biofiltration System (SSBS)—designed for stormwater treatment within confined urban spaces. The system was adjusted to the existing stormwater infrastructure by integrating a sedimentation tank (SED), three Permeable Reactive Barriers (PRBs), and a biofiltration zone (BIO). The SSBS was evaluated for its efficiency in removing nutrients and sediments, focusing on the performance of PRBs. Our findings showed limited sediment removal in SED and PRBs due to spatial constraints and a high Hydraulic Loading Rate (HLR = 1.31 m/d), achieving an average of 13.6% Total Suspended Solids (TSS) removal. However, PRBs demonstrated effective removal of ammonium (43.4%) and phosphate (59.3%), potentially due to sorption and biofilm activity, with dominant microbial communities including Proteobacteria, Bacteroidetes, and nutrient-transforming taxa such as Nitrospirae. Interestingly, PRBs increased nitrite levels (57.1%) but did not significantly impact nitrate, chloride, or TSS. The BIO zone further enhanced nutrient retention (56% PO4–P) and served as a sink for TSS (52%). This study underscores the potential for integrating traditional urban infrastructure with NbS in a sequential stormwater treatment system, demonstrating its effectiveness in space-constrained urban environments.

Nano-Fe3O4/FeCO3 modified red soil-based biofilter for simultaneous removal of nitrate, phosphate and heavy metals: Optimization, microbial community and possible mechanism

The pollution of nitrogen, phosphorus and heavy metals in surface water is becoming more and more serious, affecting the safety of water quality. In this study, three biofilters were constructed using iron-modified red soil-based filler carriers (RSC, nano-Fe3O4@RSC, and FeCO3@RSC) combined with strain Zoogloea sp. ZP7 to simultaneously remove nitrate (NO3--N), phosphate (PO43--P), copper (Cu2+), and zinc (Zn2+). The long-term operation results showed that the three groups of biofilters could remove 85.0, 90.0, and 89.8% of NO3--N, respectively. Furthermore, the addition of iron compounds enhanced the removal of PO43--P and the resistance to the stress of Cu2+ and Zn2+ in the biofilter. The analysis illustrated that iron modification improved the redox activity and zeta potential of RSC surface. The secondary structure analysis of the protein showed that the microbial secreted proteins were more compact on the surface of the iron-modified RSC, which facilitated the formation of biofilm on the carrier surface. In addition, the iron-modified RSC-based biofilter also showed excellent NO3--N and PO43--P removal efficiency in the treatment of actual surface water. The microbial community analysis results showed that Zoogloea became the dominant species in the biofilter. On the other hand, the presence of iron-reducing bacteria and the expression iron cycle-related genes may contribute to denitrification under low nutrient conditions.

One-pot solvothermal synthesis of Ca-Fe-La composite for advanced removal of phosphate from aqueous solutions in a fixed-bed column: Modeling and resource utilization

The Ca-Fe-La composite was synthesized by the one-pot solvothermal method and applied to the advanced removal of phosphate from aqueous solutions in a fixed-bed column. The effects of some important process parameters on the phosphate adsorption were examined. It was found that the maximum equilibrium loading was 121.1mgg−1 at an influent phosphorus concentration of 30mgL−1, flow rate of 2.5mLmin−1, adsorbent mass of 0.5g and pH of 5.14. The Thomas and fractal-like Thomas models were used to analyze the measured breakthrough curves. Their fitting quality was diagnosed by the adjusted coefficient of determination (Adj. R2), the root of mean squared error (RMSE) and the residual plot. According to the Thomas and fractal-like Thomas models, the breakthrough time and the saturation time were solved by the fzero command of MATLAB software. Akaike information criterion (AIC) and Bayesian information criterion (BIC) were adopted to further determine the optimal model. In all cases, the phosphate adsorption on the Ca-Fe-La composite followed the fractal-like Thomas model. The phosphate loaded Ca-Fe-La composite could be used as a slow-release fertilizer and promote tomato plant growth. This work aimed to provide reliable assessment methods for the modeling of the breakthrough curves and allow for waste management and resource utilization of the phosphate loaded Ca-Fe-La composite.

Developing zirconium xerogel coagulants for deep removal of phosphorous

Deep removal of phosphorous (P) from water is a necessary measure to solve the eutrophication problem. Coagulation is both a basic treatment method for P removal and an important pretreatment process for membrane filtration. However, few coagulants can meet the both requirements. Based on the analysis on the hydrolysis behaviors of some earth-abundant metals and the solubility products of their phosphates, a series of zirconium xerogel coagulants (ZXC) was fabricated with a novel approach (the sol-gel method) and was evaluated for the removal of both organic and inorganic P in coagulation and coagulation-ultrafiltration. In terms of P removal and anti-fouling of membrane, the resultant ZXC outperformed polyzirconium chloride (PZC), polyaluminum chloride (PAC), polyferric sulfate (PFS), as well as titanium xerogel coagulant (TXC) in a wide range of pH and dose. The rapid hydrolysis of Zr4+ and the formation of Zr3(PO4)4 with a rather low solubility product are attributable to the great performance of ZXC in coagulation. This study highlights the potential of ZXC as an effective solution for enhancing the treatment of water and wastewater, particularly in achieving deep P removal and improving membrane fouling resistance, thereby contributing to more sustainable and efficient strategies for addressing eutrophication and pollutant removal.

Phosphorus removal performance of Sulfide-Based autotrophic denitrification process

Sulfide-based Autotrophic Denitrification (SAD) Process can simultaneous remove sulfurous and nitrogenous pollutants, showing a promising prospect. Beyond our expectation, it also has an efficient phosphorus (P) removal performance. The operation results demonstrated that when the influent concentration of nitrate, sulfide and phosphate was 80.55 ± 2.98 mg N/L, 380.15 ± 20.83 mg S/L and 47.70 ± 4.35 mg P/L respectively, their removal efficiency was 87.63 ± 3.12 %, 99.61 ± 1.02 % and 85.38 ± 4.07 % at the HRT of 8.8 h. However, the phosphorus removal performance disappeared once the effluent pH dropped below 8.0. The random forest regression model revealed that effluent pH had the most significant impact on phosphorus removal performance. This finding was corroborated by a mathematical model that related the phosphate removal load to effluent pHs. The combination of batch test, Standard Measurements and Testing (SMT) and X-Ray Diffraction (XRD) method revealed that the phosphorus removal performance of SAD process came from the synergies of biological phosphorus removal (29.71 ± 3.21 %) and bio-induced phosphate precipitation (70.29 ± 3.21 %). The analysis of key functional genes coding for nitrogen, sulfur and phosphorus metabolism offered an explanation for their metabolic pathways especially the phosphorus removal pathway. The study would provide some new information for the development of SAD process.

Filtro empacado con residuos de lodos de Al para la eliminación de fósforo como sistema de pulimento en una planta de tratamiento de aguas residuales

Recently, using residual aluminum sludge (Al-sludge) from drinking water treatment plants for phosphorus removal has been assessed and it has shown to be highly efficient. However, most of the studies have been conducted using synthetic water. Only a few works have applied this method to real wastewater (WW), and none of them have been tested in continuous mode, as a polishing step, in a pilot-scale, decentralized wastewater treatment plant (WWTP). This paper aimed to evaluate the performance of an immersed filter packed with a bed of residual Al-sludge as a polishing system for Phosphorous removal, in a pilot-scale, decentralized WWTP. The study determined at laboratory-scale the capacity for phosphorus removal through batch and continuous tests using both synthetic and real wastewater and evaluated the effect of retention time. Based on the results, an Al-sludge immersed filter (Al-sludge Filter) at pilot-scale was constructed, implemented, and evaluated as a polishing step for the effluent of a decentralized-WWTP. The results showed that during continuous testing with real WW, the phosphorus removal capacity was 2.55 mg P-PO43-∙g-1 per gram of Al sludge using a retention time of 120 min. The Al-sludge filter as a polishing system presented an average removal efficiency of 94 ± 8 % and an effluent concentration of under 0.50 mg P-PO43-∙l-1 during the first 20 operational days. For the next 17 days, the system removed 85 ± 9 % on average, showing an effluent concentration of under 1.0 mg P-PO43-∙l-1. From operational day 32 onwards, the removal efficiency was 63.6 ± 10.7 %, with an average effluent concentration of 2.20 ± 0.39 mg P-PO43-∙l-1.

In-situ formation of La2O2CO3 uniformly immobilized on biomass-derived carbon aerogel for enhanced phosphate removal

In the face of the dual pressures of eutrophication and phosphorus shortages, it is of utmost importance to efficiently remove and recover phosphate from wastewater. In this study, waste-biomass-derived carbon aerogel (CA) was utilized as a dispersing carrier for lanthanum (La), resulting in the successful in-situ generation of an La2O2CO3 (La3.5-CA-450) phosphate adsorbent on the CA matrix. The results demonstrated that the introduction of CA as an adsorbent led to abundant carbon defects and pore structures, which significantly enhanced its performance. Moreover, through the coordinated pyrolysis of CA and La3+, CO32−, capable of exchanging with PO43−, was generated, thereby contributing to the exceptional phosphate adsorption capacity exhibited by the adsorbent. Specifically, La3.5-CA-450 displayed a high phosphate adsorption capacity of 155.8 mg P/g (272.4 mg P/g La), with the molar ratio of P to La being 1.22:1, indicating a high utilization efficiency for La. The adsorbent exhibited exceptional performances in terms of selectivity, renewability, efficient use in natural water environments, and robust application in a broad range of synthetic availability. This research adheres to the green concept “using waste to treat waste” while providing a novel approach for preparing efficient La-based phosphate adsorbents.

Efficient and regenerative phosphate removal from wastewater using stable magnetite/magnesium iron oxide nanocomposites

Using magnetite-based nanocomposite adsorbents to remove and recycle phosphate from wastewater is crucial for controlling eutrophication and ensuring the sustainable use of phosphorus resources. However, the weak structural stability between magnetite and adsorptive nanoparticles often reduces phosphate removal efficiency in real-world applications. This instability primarily results from the loss of adsorptive nanoparticles from the magnetite surfaces, particularly when metal oxide nanoparticles are used for phosphate removal and recycling. In this study, we present a top-down approach that involves lattice locking magnesium iron oxide nanoparticles to the magnetite core, preventing magnesium loss from the magnetite surfaces. These nanocomposites exhibit exceptional performance in both phosphate recycling and removal, with a maximum adsorption capacity of 101.8 mg P·g−1. Excellent adsorption performance is also observed even in the presence of competing anions at phosphate-to-competing ion molar ratios of 1:5, 1:25, and 1:100, as well as dissolved organic matter, across a broad pH range of 4–10. The adsorbent also demonstrated minimal magnesium release during regeneration and in acidic conditions. Microscopic and spectroscopic analyses reveal that surface precipitation is the primary mechanism of phosphate removal in the magnesium-containing shells. The findings of this study address the current limitations of magnetite nanocomposites in phosphate removal, paving the way for the development of highly stable and sustainable nanocomposites for various chemical removal and recycling applications in wastewater treatment.

Efficient Capture of Phosphate From Aqueous Media Using Bimetallic La‐Zr‐MOF

ABSTRACTDeposition of excessive phosphate in natural water column caused several issues, like the eutrophication and destruction of aquatic ecosystems. Adsorption has been an effective and convenient method for phosphate elimination. Herein, a novel bimetallic metal–organic framework adsorbent, namely, La‐Zr‐MOF, was prepared, and the morphology, crystallite, characteristic functional groups, specific surface area, and composite material surfaces were analyzed using XRD, FT‐IR, SEM‐EDS, and BET. The adsorption performance of the adsorbent was systematically evaluated by batch adsorption experiments, and the adsorption thermodynamic and kinetic properties were analyzed. The results reveal that La‐Zr‐MOF exhibits a high selectivity and sorption performance for phosphate, and the adsorption of La‐Zr‐MOF follows the Langmuir and pseudo–second‐order models; the phosphate removal procedure is a chemisorption accompanied by an endothermic reaction, and the maximum capacity was 127.7 mg g−1. Combined with batch adsorption experiments, kinetic and thermodynamic studies and various characterization analyses together revealed the phosphate removal mechanism, mainly ligand exchange and electrostatic interactions.

Strain selection and adaptation of a fungal-yeast-microalgae consortium for sustainable bioethanol production and wastewater treatment from livestock wastewater

This study explores the potential of strain selection and adaptation for developing a fungi-yeast-microalgae consortium capable of integrated bioethanol production and livestock wastewater treatment. We employed a multi-stage approach involving isolation and strain selection/adaptation of these consortiums. The study started with screening some isolated fungi to grow on the cellulosic biomass of the livestock wastewater (saccharification) followed by a fermentation process using yeast for bioethanol production. The results revealed that Penicillium chrysogenum (Cla) and Saccharomyces cerevisiae (Sc) produced a remarkable 99.32 ppm of bioethanol and a concentration of glucose measuring 0.56 mg ml− 1. Following the impact of fungi and yeast, we diluted the livestock wastewater using distilled water and subsequently inoculated Nile River microalgae into the wastewater. The findings demonstrated that Chlorella vulgaris emerged as the dominant species in the microalgal community. Particularly, the growth rate reached its peak at a 5% organic load (0.105385), indicating that this concentration provided the most favorable conditions for the flourishing of microalgae. The results demonstrated the effectiveness of the microalgal treatment in removing the remaining nutrients and organic load, achieving a 92.5% reduction in ammonia, a 94.1% reduction in nitrate, and complete removal of phosphate (100%). The algal treatment also showed remarkable reductions in COD (96.5%) and BOD (96.1%). These findings underscore the potential of fungi, yeast, and Nile River microalgae in the growth and impact on livestock wastewater, with the additional benefit of bioethanol production.Graphical abstract

Modification of steel slag and its application for phosphate and ammonia removal in aquatic products processing wastewater

ABSTRACT This study aims to modify different types of steel slag by heating, characterise the material and test its ability for adsorption of phosphate and ammonia from aquatic products processing wastewater. The materials were characterised by SEM, EDS, BET and FT-IR analyses. The effects of the type of steel slag, calcination temperature in steel slag modification, pH, contact time, adsorbent mass and initial pollutant concentration were investigated using the one-factor-at-a-time approach. The results show that the adsorption kinetic of the samples followed the pseudo-second-order model, whereas their adsorption isotherm fitted well with the monomolecular adsorptive Langmuir with a maximum phosphate adsorption capacity of 45.045 mgPO43-/g. Optimisation using Response Surface Methodology was conducted with the independent factors (adsorbent doses, contact time and calcination temperature of steel slag) and response (removal efficiency of phosphate). The temperature and dosage of the material significantly affected phosphate removal efficiency and optimisation conditions were suggested. Validation of one optimum condition at the calcination temperature of 801°C, the adsorbent dosage of 11.9 g/L and the contact time of 72 min using real aquatic products processing wastewater resulted in the removal efficiencies of 86.93, 87.59, 7.76 and 7.58% for phosphate, total phosphorus, ammonia and total nitrogen, respectively.